News

20.November.07
The ASP CHAPS data archive at BNL is the permanent repository for data considered by the PI to be in final form or suitable for open distribution. Many of you have posted preliminary data to the temporary ARM/CHAPS Archive, which was intended only to foster collaboration and data sharing during the field campaign and for a short time thereafter. Although the official date to get data into the ASP/CHAPS site is December 28^th (6 months since the end of the campaign, as stated in the DOE ASP data sharing policy, www.asp.bnl.gov/datapolicyR3.html), the reality is that with vacations, AGU and the holidays, we should get it in sooner.

So for those really great and efficient scientists who have posted data at the 'old' ARM/CHAPS site and consider it suitable for official release:

• please send me (carl.berkowitz@pnl.gov), Larry Berg (larry.berg@pnl.gov) and Stephen Springston (srs@bnl.gov) an e-mail stating that your data can be transferred to the permanent ASP/CHAPS site at BNL.
• Data archived to date can be found at: ftp://ftp.asd.bnl.gov/pub/ASP%20Field%20Programs/2007CHAPS/READ%20ME.TXT and currently includes navigation, met, trace gas, optical particle probe data, and both LAPA and PAPA photoaccoustic instrument sets. 'Read only' password for the CHAPS data set (use limited to CHAPS PIs for 1 year) is also available from connor.flynn@pnl.gov or larry.berg@pnl.gov

For those who have not posted final form data to the 'old' ARM/CHAPS site:

• please post your data here (along with a readme.txt file that states how to contact you and giving a description of data, the units, QA issues) as soon as possible.
• Posting the data is easily done by going to ftp://iopshare.archive.arm.gov. If you have misplaced the username/password information contact connor.flynn@pnl.gov or larry.berg@pnl.gov. Once you've posted your official release data, please send carl.berkowitz@pnl.gov, srs@bnl.gov and larry.berg@pnl.gov an e-mail stating that your data can be transferred to the permanent ASP/CHAPS site at BNL.

Thanks for taking the time to get closure on this important stage of the campaign.

Also, don't forget about our informal CHAPS science meeting at the AGU conference, Wednesday, December 12, 18:00, just outside MW3014 (right after the session "Urban Effects on Radiative Forcing by Aerosol and Clouds II," which starts at 16:00). From this location we'll move to a yet undetermined place where we can talk. Hopefully we'll have a draft overview article on CHAPS to guide the discussion.

04.September.07
Another reminder that September 6 is the submission deadline for AGU, and that Steve Ghan has invited us to submit 'first look' results from CHAPS at his session (A38) "Cloud Effects on Aerosol." The link to the session is http://www.agu.org/meetings/fm07/?content=search&show=detail&sessid=530. Please let me know if you're submitting a CHAPS related abstract.

We have an 'official' CHAPS data repository. Thanks go to Connor Flynn for getting us a temporary home at the ARM Archive site, and to Stephen Springston for getting our permanent home on the ASP site. Thank you, Connor and Stephen!

Details and why you should care: Data posted at the ARM site, ftp://chaXXXXX@iopshare.archive.arm.gov/ [where chaXXXXX is the username provided separately) will be moved to ftp://ftp.asd.bnl.gov/pub/ASP%20Field%20Programs/2007CHAPS/ on October 1st, per an earlier note to CHAPS PI's. A Read Me file (directing users to the new site) will be placed where the data previously resided at the ARM site. The new site has a READ ME.TXT file explaining access procedures and a Flight Guide Excel spreadsheet detailing the 12 research flights along with aloft times. For now, only Stephen can update the new site so please send revisions or data you haven't yet set in to him or me (Carl).

Access to data within the ./2007CHAPS folder is a password protected folder cleverly named ./Participants). Point your cursor to the right of 'Flight Guide 070830.xls, right click and select "login as..." Contact Stephen, Larry Berg or me for your username and password.

09.August.07
Steve Ghan is convening a session at the AGU fall meeting on cloud effects on aerosols. He's encouraging us to submit posters and presentations on the CHAPS field campaign. This would, of course, be 'first look' results only. We'll have at least one overview presentation but it would help all of us to present material on our respective measurements. Furthermore, your participation will help jumpstart the publications that are so important to ASP, your home organizations and each of you individually. The link to the session is http://www.agu.org/meetings/fm07/?content=search&show=detail&sessid=530 and the deadline for submitting abstracts is September 6.

Anticipating that there could be many multi-author presentations (oral and poster), please check that the data sets on the CHAPS FTP site are up to date. On or about October 1st, we will be moving these files to the ASP Data Archive at Brookhaven, and would like to have the latest and greatest data when this move occurs. Although the ASP Data Policy Statement allows for up to 6 months for data submission, I would strongly urge you to check and revise as needed your first-look data sets by October 1st so our common observations can be made available to all investigators as they prepare material for the AGU Fall meeting. A new username and password will be sent to all participants giving them access to this site. PIs are referred to ASP Data Policy Statement (http://www.asp.bnl.gov/datapolicyR3.html) for additional guidance.

If data already submitted does not yet have the following features, please add them to your data file on the CHAPS FTP site.

• A comma separated value (CSV) file for each flight
• All time stamps be of the format yyyy-mm-dd, hh:mm:ss, (year, month day), hour, minute, second. All times must be UTC.
• Each data set should include a short text file stating
• the name, affiliation, e-mail and phone number of the investigator
• The name, model and serial number of the instrument
• The calibration status of the instrument
• Status of the data (preliminary, good as it will get, final . . .)
• The time response of the instrument
• Expected detection limits of the instrument.
• roblems encountered in the field (e.g., drift, data drop outs, needed empirical corrections. etc.).
• Measurements based on one observation should be entered with the time stamp corresponding to that one observation. Measurements that reflect an average over several observations should be entered with the time stamp corresponding to the start of the observation period, and then be repeated throughout the observation interval.

Contact Connor Flynn for instructions about accessing the FTP site. Connor said he'd be happy to help with questions about folder access, revising old files, etc. (connor.flynn@pnl.gov; 509-375-2041)

16.July.07
On the last day of the CHAPS campaign, we reviewed what was well done in preparation for (and during) the campaign, and what could have been done better. A summary of this informal discussion is posted on the CHAPS webpage and can be viewed from the 'Lessons Learned' link in the left navigation. We've posted it with the hope that future ASP campaigners will benefit from our experience. Thanks to all for your input, and please contact Carl if you have additional suggestions.

The next step in the 'campaign' will be a special breakout session at the ASP Science Team Meeting when we'll have a chance to present first-look results and refine research questions in light of the actual observations made during the field study. Information on both the Science Team meeting and breakout session should be showing up in our mail boxes in the near future.

28.June.07—Final News From the Field
Although broken skies were reported this morning and continue to be part of the forecast for southwest Kansas, the high potential for thunderstorms both en route and on the return from Ponca City convinced us to scrub this mission. And with more of the same weather forecast for tomorrow, research flights for CHAPS are officially over. The next G-1 flight will be this Saturday, when it departs from Ponca City to fly back to it's home base in Richland, Washington.

This afternoon (Thursday) and Friday will be spent doing final cross-checks and calibrations on the instruments and packing things up. The G-1 will be rolled onto the tarmac for one such set of intercomparisons. We are also planning to have a general round table discussion to consider presentations the CHAPS team can make at this winter's AGU meeting and to toss out ideas for future manuscripts (all such thinking and discussion being preliminary at this early stage). Planning is also underway with the ASP management team to have a special break out session at the next science team meeting.

Readers of these daily summaries are familiar with many of the folks on the CHAPS field team and the work they've done to make this campaign a success. Unfortunately, we've not been able to get a complete list of those who've worked behind the scenes to make this campaign happen. So to the folks back home at Aerodyne Corporation, Argonne National Laboratory, Brookhaven National Laboratory, Los Alamos National Laboratory, NASA, NOAA and PNNL . . .thanks from everybody on the field team to the folks back home for doing a great job in laying the groundwork, dealing with problems that arose during our absence and putting up with our daily calls home for help. You folks are champions!

(left to right) Connor Flynn, Gunnar Senum and Haf Jonsson compare data from CAPS probes on the G-1 and CIRPAS Twin Otter. Photo by John Hubbe. (Large image)

27.June.07
The opening words at this morning's weather briefing: "It will not rain all the time over the next few days." This was followed by news that the Southern Great Plains site was being evacuated due to flooding. We also received a photograph of what looked like a rice field just east of Ponca City . . .only it was a cotton field.

This morning's activities were carried out as planned; waiting and watching the weather. Between 7AM and about 9AM, the team waited and watched. At 9AM we pushed our 11AM take off to 12PM to allow dropping cloud top heights to drop some more. After some more waiting and watching, we pushed our 12PM take off to 2PM. At around 11:30AM, after more w&w'ing, we said 'this ain't working' and scrubbed for the day as the satellite estimate of cloud top heights started rising again and the drizzle intensified. Our apologies to the crew who somehow missed the message of this last cancellation. On the bright side, Gunnar Senum and Haf Jonsson (with the CIRPAS Twin Otter) made use of the down time to do a cross-comparison of the G-1 CAPS probe with the probe on the Twin Otter.

Tomorrow's schedule: Pre-flight briefing at 9AM, final go/no-go decision at 10:15AM, scheduled take-off at 11AM. Plans call for the G-1 and NASA King Air to fly west, to the east side of the cyclone associated with the precipitation drenching Oklahoma. The waypoints for the sampling component of the mission define a triangle located over southwest Kansas. The G-1 will make one lap around these waypoints at a cloud-top altitude to be defined from observations from the King Air crew, who will be following a similar set of waypoints at 28,000 feet. Two laps by the G-1 will then be done at lower altitudes, one within clouds (with the AMS on CVI inlet) and another with the AMS on the isokinetic inlet.

26.June.07
The G-1 was rolled out of the hangar at 5:30AM this morning and rolled back into the hangar at 8AM as the forecast drizzle set in. Most of the day was spent looking at data, calibrating instruments or watching the rain, which is why we noticed periods when it wasn't raining and the clouds were thinner. The forecast for tomorrow calls for more of the same, which hopefully means we'll again have periods when the clouds are thinner. Which is a great segue into tomorrow's flight plan.

Tomorrow's flight plan is a based on a 'wait and see' strategy, whereby we propose to standby for those periods when it isn't raining and the clouds are thinner. We have filed for a 10AM take-off (8:30AM pre-flight briefing) and will try to fly a two-tiered triangle pattern due east of Ponca City, with a 30 nm upper triangle skimming cloud top and a lower 30 nm triangle flown within the clouds. By filing for a 10AM take off we can depart anytime between 10AM and 12PM. We have also filed for a second take-off at 2PM (window between 2PM and 4PM) giving us a relatively long period in which to fly. This plan is (a) short, (b) easy to carry out and (c) relies largely on real-time, or close to real time, observations, with minimal reliance on forecasts since the sampling area is due east of the airport. Basically, we'll be on the lookout for opportunities to fly.

Joining us on this mission will be the NASA King Air and the CIRPAS Twin Otter. This combined CHAPS/CLASIC mission will occur only if

• The sampling domain shows either no echoes or only blue radar echoes on the Norman, OK, weather radar and the Aviation Radar;
• the radar echoes show no evidence of stronger convection moving into the sampling area;
• pilot reports indicate cloud tops at an altitude suited for sampling by the G-1; and
• there is no precipitation at the Ponca City Airport or to the skies east of the airport.

'Cloud top' will be defined by the flight team on the NASA King Air who will fly into the sampling area in advance of the other two aircraft. Altitudes will be adjusted to put the G-1 at the top of the lowest cloud layer, the CIRPAS Twin Otter at least 2000 feet above the G-1, and the King Air well above these other two aircraft.

As they say, "if it was easy, everybody would be doing it."

25.June.07
Today was the flight of the campaign starting with the G-1 take off at 11AM, with all instruments working and the weather cooperating. Two layers of clouds were sampled over OKC, with measurements made below, within and above fields of fair weather cumulus clouds. Gunnar noted that the OKC plume was encountered at all three layers and was easily identified by its signature in CO, Betsy saw an increase in the CPC counts, and Liz reported elevated levels of benzene that were correlated with CO. The plume signal was stronger along the inner half-hexagon and weaker but still present at the outer half-hex. Liz also reported that the AMS was able to track the size resolved composition of aerosols along the inner track. John H. noted that a modified power transfer protocol was successful, with no electrical problems during take-off. The only instrument problems involved our TANS GPS receiver, (necessary to calculate onboard winds) and one (out of two) CCN instruments, which were not operational. The NASA B-200 was not able to participate in today's flight because of a mechanical problem that arose just minutes before their scheduled launch time, a situation the G-1 team is very sympathetic to. Crews from both aircraft are anxious to carry out a repeat of today's mission.

There was outstanding cooperation for today's flight between the surface site crew in Edmund and the G-1. The surface crew (Misha Pekour, Rich Coulter and Tim Miller) provided real-time wind observations over the sampling domain that helped position the G-1 to find the OKC plume. Misha also kept us abreast of cloud conditions over the sampling area during the early stages of the flight, noting that the boundary layer depth (as measured by the profiler and sonde launches) would not likely reach the lifting condensation level at the preliminary launch time of 10AM. The departure time of the G?1 was pushed back to 11AM as a result of these observations, which proved to be critical to the success of this mission.

It's going to be hard to have a better flight than the one we had today, but that the target for tomorrow (Tuesday). A cyclonic circulation pattern over the state is developing through a deep column of the atmosphere that, along with abundant moisture, is forecast to lead to a lot of rain tomorrow and Wednesday. Deep cumuliform clouds are forecast for later in the afternoon, so we've filed for a 9AM take-off tomorrow, one hour earlier than we've done in the past. Greenwood Aviation will open the hangar at 5:30AM for scientists who need to start pumping down their instruments or need some additional time to prepare for the flight. There will be a 6AM weather briefing with a final decision for take-off time to be made at the 7:30AM pre-flight briefing. It may also be recommended at the pre-flight briefing that the take-off be postponed till 10AM if conditions warrant.

In the event we need to scrub tomorrow's morning flight, we have also filed for a short 'Ponca City Triangle' flight pattern in the afternoon. This plan was described in a previous note.

Rich Coulter and Misha Pekour provided the above screen shot of today's observations from the radar wind profiler (rwp) and micropulse lidar (mpl) operated at our surface site just north of OKC. Rich sent the following note with this figure: This is a screen picture of the rwp data from 0530 - 1730 UTM from the ground site. The mixed layer can be seen rising grudgingly to about 800 m by the end of the day (top right). The most interesting plot is the lower right, which shows the wind direction profiles for each half hour during the period. Note that the colors for each successive half-hour is listed descending from the top on the right side of the plot (thus 3 shades of red are the last 3 half-hour periods. So, the wind direction during most of the day went from SE near the surface to S at or below the top of the mixed layer, then a shear back to the NE above 2 km remains in effect throughout most of the day. Wind speeds were quite light (< 10 m/s) throughout the profile. The layer around 2 km was evident throughout the day and was also an isolated, thin maximum in aerosols as seen by the mpl. (Large image)

24.June.07
Another half-hexagonal flight around Oklahoma City was done this morning. The G-1 left at 10AM CDT and encountered the Oklahoma City plume during the northwest segment of the inner hexagon. Plume identification was based on elevated CO and backscatter. The plume position to the northwest was somewhat out of line with the Oklahoma METARS that were reporting winds from 200deg (the south-southwest) for the area around Oklahoma City. Whether or not the G-1 will encounter the Oklahoma City plume depends strongly on the growth rate of the mixed layer and the history of wind shear throughout the lower atmosphere.

The observation of plume location by the G-1 seems to be consistent with observations made by Rich and Misha on the ground. Stay tuned for more analysis relating these observations to those made from the aircraft.

Today's flight was a good news-bad news situation for instruments on the CVI inlet. The bad news was that there were problems with the CVI inlet.. The good news was that there were few clouds for the CVI instruments to sample, anyway. The two mass spectrometers (AMS and PTR-MS) had plumbing problems toward the end of the flight, and the G-1 returned somewhat earlier than its expected arrival at 2PM.

Tomorrow's flight will be similar to the flight done this morning since the conditions are forecast to be similar. We're planning a 10AM take-off with an 8:30AM pre-flight briefing. Consideration was given to pushing the departure time back to 11AM in light of the potential for small cu's to develop in the early afternoon.. However, the small cu's that we hope to see forming during the early part of the flight have the potential to grow into bigger cu's later in the day. So for now we're sticking to the earlier departure time. This could change if the early morning forecast discussion suggests it's appropriate to do so. While we have filed for a second flight plan, the "triangle" plan, we will only consider doing it if the first flight is either scrubbed or cut short.

Sampling has been difficult because of the wet weather we've had for much of the campaign. This, plus the brief time we have remaining led the field team to consider what kind of short, easy flight could be done if the weather and energy level of the team allowed. We wanted a flight plan that required no more planning than walking outside the hangar and looking at the sky. The "triangle" plan seems to meet these needs; if the skies to the east of Ponca City are filled with shallow cumulus clouds, as they were this afternoon, the new plan has the G-1 flying a triangle pattern over this relatively open air space, four laps around the triangle (one of our low-altitude lap, two mid-cloud level laps and one above-cloud top lap). The expected time aloft is two hours. The triangular shape is designed to remove any bias from the winds rather than having anything to do with sampling within any anthropogenic plumes. The scientific goal is to better characterize aerosol partitioning within clouds. It also gives us a relatively easy-to-do flight plan we can use if our early morning flights are cut short.

Update on G-1 hours: We've used approximately 29 hours out of the 60 hours allocated for the CHAPS campaign. The G-1 has flown on 12 occasions including flights for testing the aircraft mechanics.

MPL is scanning from 75 deg elevation to 5 deg, pointing to the North, then from 5 to 75 deg, pointing to the South. Time is right to left on X axis; Y axis is height. (Large image)

23.June.07
With less than a week remaining in the campaign, 'launch fever' has set in among the scientists. Two flight plans were filed with the FAA for today, and two flights were flown. The first flight left Greenwood Aviation shortly after 10AM and was amazing! The newly designed hexagonal pattern picked up the plume on the inner ring, with CO levels in excess of 120ppb and high aerosol concentrations to the north-northeast of the city. Broken cloud fields were encountered, and the measurements consist of a mix of in-cloud and out of cloud sampling. The NASA B-200 was directly above the G-1 for most of the mission. It was a terrific flight where everything worked just as it should. With the success of the AM flight, a second flight was carried out, departing from the Greenwood hanger at about 3PM. Heavy weather precluded a return to Oklahoma City so a set of low-level, cloud-level and above-cloud levels transects were flown on the ferry path from Ponca City to Oklahoma City. While fair weather cu's were observed over Ponca City, there was heavy weather and a surprising number of small private aircraft between the waypoints near Ponca City and just north of Stillwater. We probably will not carry out scientific missions in this area again as a result of the many small aircraft frequenting this airspace at lower altitudes.

Good news with the CCN measurements; the .03% CCN unit worked like a charm on both the morning and afternoon flights, showing elevated values that followed the CO signal. Yury Desyaterik and John Ogren have ordered a replacement OPC detection module from Droplet Measurement Technology for the non-working CCN, and expect delivery of these replacement parts on Monday.

Boundary layer characteristics during the CLASIC-CHAPS campaign: Not all CLASIC-CHAPS investigators may be aware that we have a surface-based remote sensing capability at the CHAPS surface site just north of Edmond, OK. Rich Coulter, Mikhail Pekour and Tim Martin have been operating this site since June 1st. In addition to launching radiosondes on days when the G-1 is in the air and maintaining a radar wind profiler, they are also deploying a micropulse lidar system. Some notes on this summer's observations of boundary layer near OKC are included below.

We are characterizing the mixed layer and lower troposphere using the radar wind profiler (rwp) micro pulse lidar (mpl) and the radiosonde system. In fact, the height of the mixed layer can be determined with information from any of the three. The two remote sensors (rwp and mpl) provide continuous info (half-hour averages for the rwp, as small as 30 sec for the mpl) while the radiosonde provides ground truth grab samples at 12, 15,17,19, and 21 UTC on flight days. In fact for this field study we rely on the rwp for mixed layer depth and dynamics.

The daytime mixed layer has been, for the most part, quite feeble since June 4. Only on June 4, 11, and 12 did it exceed 1.5 km (actually reached 2 km on June 4), and was less than 1 km in depth on 9 of the remaining days. On several occasions, there is little development to be seen because all the available energy (what there is to be had with all the cloud cover) is going into latent heat because of the abundant soil moisture. Winds have been variable as well, both in time and space (vertically). Generally the maximum height occurs around 1400 - 1500 LST with liftoff beginning around 0900 LST.

Because we have modified the mpl to allow for full azimuth and elevation scanning, we have been using it in several different scenarios. North- South and East - West scans at 5 deg increments in elevation provide information on the horizontal homogeneity of the mixed layer. Thus far we have managed to avoid pointing directly at the sun, which would be a bad thing. . . A second scanning exercise is performed by scanning from East to North to West to South (and back) at constant elevations. During daytime, our maximum range at low elevations is around 5 km, depending on pollution levels. Combining the information from these scanning strategies should give some 'feel' as to our location within the urban plume (or not). A third method being employed with the mpl is to scan within the neighborhood of individual clouds to observe inflow and outflow of aerosols. While we think we have some useful cases so far, the preponderance of clouds makes the data analysis difficult. A digital camera mounted on the mpl is invaluable in the interpretation of the data and ancillary data from the rwp will also be most valuable.

Tomorrow's (Sunday's) flight plans call for a 10AM take-off, with a pre-flight briefing in front of the G-1 at 8:30AM. The flight plan is identical to today's morning mission. The weather forecast suggests that persistence will yield as good a prediction as anything else, with scattered showers, mostly shallow Cu, and deep convection in late afternoon.

Check out what the folks in the CIRPAS Twin Otter were seeing during the June 19 instrument intercomparison segment of the A-Train Underflight. Thanks to Roy Woods of the CIRPAS Twin Otter team for providing this photo. (Large image)

22.June.07
Today's 12PM flight was scrubbed when a fault light came on in one of the inverters that sends AC power to the science instruments. John Hubbe swapped out the problem inverter, replaced it with another unit on the aircraft that wasn't being used and also ordered a new inverter as a backup. The best question of the day came around 5:30PM when pilot Bob Hannigan asked the scientists what time they wanted to fly tomorrow! Many thanks to John, Matt Newburn and Bob for getting this potential show-stopper of a problem under control in such a short time.

Matt Newburn thinks there may have been a power surge associated with the damaged inverter. PI's may want to check their instruments prior to tomorrow's flight. The hangar and G-1 will be open tomorrow morning at 7AM. Contact Matt or John Hubbe to test the instruments prior to flying tomorrow.

Flying tomorrow (Saturday) will (hopefully) commence at 10AM, with the new half-hexagonal patterns described in yesterday's "Summary." These flight plans have undergone minor revisions,; the most recent versions are attached with this note. The three plans each represent an option to be selected by the flight crew based on measurements made during the flight.

G1 north | G1 northeast | G1 northwest

Today's weather forecast calls for ridging to continue over North America with the exception of the central US (= Oklahoma!) that still has enough cyclonic circulation to be a candidate for thunderstorm development. Winds should be light and variable with a slight southerly component, and precipitation will be scattered over the region with shallow cu's forming late morning. The next weather item of interest is now a depression forming off the coast of Texas that could hit our area early next week. Considering all the rain we've had and the soggy state of the soil, Mark Miller noted that "Any system that moves north will think its moving over the ocean." At the start of the campaign, the geographical area of CLASIC-CHAPS could be readily identified on the national weather maps by a closed low that stayed parked over our area for almost a week. Towards the middle of the campaign we could be found by X's indicating maxima in positive vorticity. Guess which state is in the center of a circle drawn by the NWS to show the inland termination point for the tropical depression?

It was noted yesterday that measurements of the FIMS and TSEMS were in good agreement. Jason Olfert/BNL offered to share more details of these results in the following note:

Here is one of the comparisons of the FIMS and TSEMS that I did on the ground yesterday. This figure shows the size distribution of particles as measured by the TSEMS and FIMS. As you can see the FIMS follows the TSEMS quite well except for the decrease in number concentration at smaller sizes. This figure shows the % difference between the FIMS and TSEMS. From the figure one can see that there are less particles in the FIMS at smaller particles sizes. This is as expected. The inlet of the FIMS, which includes a neutralizer, orifice, laminar flow element etc., has not yet been characterized and the particle losses in the inlet have not yet been accounted for. We would expect that more smaller particles (i.e. 40 nm particles) would be lost relative to larger particles (i.e. 110 nm particles). When I get back to the lab I will characterize the inlet penetration efficiency and correct the FIMS data. This procedure is done with all particle sizing instruments, but I have not yet been able to do it for the FIMS yet.

Don't try this at home: a picture from the G-1 taken during the instrument intercomparison phase of the A-train underflight. Enlarge image

21.June.07
Today was a no-fly down day, with much work being done on selected instruments and a data review session this morning. Liz Alexander started our 9AM roundtable data discussion with a presentation of preliminary PTR-MS observations of isoprene (M69) and several related species. Liz reported seeing the signal only downwind of Oklahoma City and at concentrations well in excess of what would be expected from a biogenic source. Although other biogenic compounds were seen, they were at much lower concentrations which also makes it hard to understand how this could be a biogenic source. Jason Olfert then described his first observations on the TSEMS, FIMS and PCASP, finding good agreement with three instruments, although the PCASP was somewhat outside the range of the other instruments, possibly due to how the bins are defined for the smaller sizes. The group consensus on Jason's observations was articulated by John Ogren who said "Agreement above 200nm is remarkable." From here, the discussion moved to the CCN where Gunnar Senum suggested that some of the problems this instrument has been seeing could be related to power on the G-1. Discussions also included what aerosol instrument comparisons could be done on the ground between the G-1 instruments and those onboard the CIRPAS Twin Otter. These round table discussions are proving to be useful not only for shaking down the measurements but are also a good way to learn about the many instruments being flown aboard the G-1.

Despite a dome of high pressure over much of the southern United States, there's still one vorticity max in its center; parked right over our study area. In the 500mb prog, Xs indicate local maximum of positive vorticity, with all the stormy weather typically associated with this feature.

An 11AM G-1 flight is planned for tomorrow (Friday). By way of introduction to tomorrow's proposed flight plans, it should be noted that both pilots and flight crews have reported there have been a number of times when the winds observed during the flights were quite different than those predicted (e.g., yesterday's flight was designed for southerly winds but the observed winds were from the east). John Ogren, John Hubbe, Bob Hannigan, Chris Hostetler and Berkowitz spent considerable time this afternoon trying to come up with a flight plan that would be less sensitive to changes in the wind due to bad forecasts or to the presence of vertical wind shear (where the wind velocity at one altitude is different than that at another).

The first cut in coming up with a more robust plan was a simple circumnavigation around OKC, assuring we'd intersect the plume regardless of wind direction. The second design consisted of two long orthogonal legs with the apex of the resulting triangle pointing in the forecast direction of the wind. Chris Hostetler came up with what we think is the best solution, consisting of two half -hexagonal patterns located to the north of OKC. The actual wind direction observed along the inner half-hexagonal line will be used to determine which part of an outer half-hexagonal pattern should be sampled. A pattern will be filed with the FAA that assumes southerly flow so that the G1 spends time sampling due north of OKC with the understanding that the pilots and crew can switch to a pattern that assumes southwesterly flow so the G1 samples along the northeast part of the outer hexagon or southeasterly flow so that G1 samples along the northwest part of the hexagon. Assorted legs have been cut short to keep the mission length to less than 4 hours. Check with Berkowitz or Ogren for the final version and a more lucid explanation.

20.June.07
Some serious storms over the area last night . . .lots of electricity, sound effects and rain. The residual moisture and atmospheric instability did not go away today (Wednesday). The predicted clearing in the weather did not develop and the National Weather Service issued a severe weather watch just before the G-1's scheduled 1PM launch. The warning seemed to be based on a newly developed mesoscale convective system (MCS) that formed over the area last night. Pilots and PI's did a quick huddle and decided to continue with today's flight with the agreement that the G-1 would return to Ponca City if any heavy weather was encountered.

The NASA King Air has been flying overhead of the G-1 during our missions making remote measurements of many of the in situ measurements made by the G-1. A layer of clouds prevented the King Air from seeing the G-1 today so the King Air pulled off the G-1 flight line and moved to sample over the Southern Great Plains site. The G-1 continued on its planned route. During the post-flight debriefing, the flight team reported seeing thunderstorms to the west of OKC, and were bumping into them at some of the western waypoints. Very clean conditions were reported during today's flight, with the Condensation Particle counter (CPC) measuring only 600 aerosols per cc and nephelometer readings of less than 1.5mM-1. This is very, very clean. But of course not everything made sense; ozone levels aloft of ~64ppb were observed although the CO mixing ratios were locked in on 80ppb during the entire flight. The group consensus was that the ozone might have been formed from NOx produced by all the lightning that occurred last night.

The above noted weather also complicated logistics with Gunnar Senum's flight from NYC being cancelled, thus delaying his arrival. We're now hoping Gunnar will join us in Ponca City later Wednesday evening. Gunnar's arrival is good news. The bad news is that we're losing Stephen Springston and Yin-Nan Lee. Both have made a major contribution to the project, not only scientifically but in providing great camaraderie.

We want to mention that scientists at the CHAPS surface site in Edmund, OK, have been collecting measurements directly below the G-1 during its OKC flights. Misha Pekour, Rich Coulter and Tim Martin have been making sure a Total Sky Imager is working continuously, along with a Micropulse Pulse Lidar, radar profiler wind profiler and a suite of in situ measurements. They've been doing this in very hot, humid and windy conditions, encountering their share of instrument problems. One interesting feature they observed during a recent radiosonde launch had a radiosonde going up as normal, but then descending, then going back up again, then down, then up...Tim Martin was the first to note that a balloon going through supercooled water would pick up ice that would increase its weight, pulling it down to warmer conditions where the ice would melt, so the balloon goes back up again, more icing, then down, then up.

In yesterday's summary we noted that a bulb burned out on the G-1 nephelometer. Betsy Andrews noted that this statement by itself makes things sound a little grimmer than they were. We had a second nephelometer on board the G1 during this (and all) flight that was sampling off the isokinetic inlet so that despite the bulb failure in the first neph we do still have spectral scattering/backscattering measurements for the whole flight that are comparable to the other aircraft measurements and useful for validation. Sorry for any confusion, and thanks to Betsy for pointing this out.

As a follow up to yesterday's success with the A-Train underflight, Chris Hostetler gave John Ogren the coordinates for the NASA B-200 King Air flight so John could add this aircraft to the figure. John estimates that the King Air was 2.3 statute miles from Point C at 19:53:01Z yesterday. What is important here is that all the planes lay upon the line defined by what the A-Train would 'see' as it passed over head. Pretty good precision flying.

Tomorrow (Thursday) will be a down day for flying as a result of all the uncertainty in the weather. A vorticity max (or two or maybe three, depending on which prog one looks at. . .I'm not making this up!) is shown floating around southern (or northern) Oklahoma with lots of moisture in the eastern (or western) part of the state. A new MCS may (or may not) form to the west of the study site, etc., etc.

There will be another round-table data discussion tomorrow (Thursday), at 9AM. We want to continue going over recent observations, instrument performance, etc.

The GPS logs from the G-1, Cessna 206, and Twin Otter from today's underflight of the A-Train of satellites show just how fabulous our pilots are. The pilots were asked to pass over a given point at a specific time, and the plot shows just how close they came. Fortunately, they were assigned different altitudes!
(Large image)

The long awaited A-train satellite under flight, involving the Duke University helicopter, the CIRPAS Twin Otter, the Cessna 206, the NASA King Air and the DOE G-1 occurred at 19hr 53min UTC(14hr 53min CDT) with all of the aircraft very closely stacked on top of each other at Point C in the attached flight.

To the best of our knowledge, never before have this many research aircraft coordinated sampling within a deep column of the atmosphere at the same time. John Ogren (NOAA/ESRL Global Monitoring Division) shared these thoughts on the intercomparison flight in an e-mail titled "amazing pilots at work":

The tick marks in this blow-up of a sectional aeronautical chart are 1 nautical mile apart, and the box labeled "C" is the target point. All three planes were within one statute mile of the target point at the appointed time, with the Twin Otter winning bragging rights at a separation of only 0.15 mile. All were within 1000 feet of the ground track of the satellites, shown as a thin green line in the image.

Hats off to Bob Hannigan and Dick Hone (G-1), Mike Hubbell and Chris McGuire (CIRPAS Twin Otter), and Bob Fristoe (Cessna 206) for a superb piece of navigation!

The CIRPAS Twin Otter and G-1 then went on to carry out a side by side instrument intercomparison along Points G to E1, with the G-1 coming up from behind and then passing the Otter.

Several interesting observations are coming out of the data and were seen during today's flight. A pronounced haze layer was detected by the G-1 instruments at ~6K feet during today's flight, and also seen by the NASA King Air HSRL that was flying some 10k feet overhead. This is an obvious case study analysis comparing what the remote sensing instrument aloft saw relative to the in situ observations made by the G-1. One very curious feature noticed by several instruments was a sudden increase in scattering and aerosol number immediately prior to entry into a cloud but never seen when the G-1 was exiting a cloud. Some instrument problems did arise, including a second bulb burnout on Betsy Andrew's nephelometer another hot wire failure on the CAPS probe and continued noise on the CCN instruments. On a positive note, Dubey's LAPA worked like a charm on today's flight!

The headline in today's "The Oklahoman' read 'Inundated. . .flooding, pets stranded on roofs, rain swamps. . .", etc. Really bad news for the poor folks hit by the terrible flooding this area has seen. The good news is that the weather appears to be moving into more of a summer regime ridging and anticyclonic flow setting in for the next few days. And plans are being by the CHAPS scientists to cash in on these drier conditions. As the residual cirrus from overnight t'storms move out later in the day tomorrow/Wednesday we expect the associated increase in insolation to drive the start of small cu formation. Hoping to stay away from the maximum forecast temperatures (up to the lower 90's), we're aiming for a 12PM take off with a 10AM pre-flight briefing. Winds are expected to be light and out of the south or southeast. We're planning an OKC cloud sampling flight with the final orientation to be decided after tomorrow's weather briefing.

Our 9AM round table discussion on data quality this morning was productive, but not long enough (we had to limit it to one hour). We reviewed the pressure fluctuations on the isokinetic probe and came up with some tests to help peg down its cause and evaluate its effect on instruments downstream of the inlet. A similar discussion ensued about the CCN instruments, with the group suggesting several possibilities for the occasional sudden reduction in signal.

G-1 Stack Pattern 2 Southeast Flow | G-1 Stack Pattern 2 Southerly Flow

For the record, we've had 6 flights (June 4, 5, 7, 11, 17 and 19th), with a total of ~16 hours. That leaves the G-1 with 44 remaining research hours during the campaign.

U.S. weather forecast for Monday, June 18, 2007. (image from NOAA).
(Large image)

18.June.07
The sense that today was a good down-day was confirmed at breakfast when The Weather Channel indicated a tornado watch to the south of Oklahoma City. Attached with this note (noaa.gif) is one of the visual aides included in the CLASIC-CHAPS morning forecast session.

Most of the flight crew worked on instrument calibrations and maintenance. The hot-wire on the CAPS probe was not working during yesterday’s flight and received needed attention from Stephen Springston.

Weather for tomorrow (Tuesday), June 19th looks favorable for sampling. The CLASIC-CHAPS forecasters are expecting the frontal boundary to be around OKC by morning, oriented more or less E-W, and to slowly migrate a bit further to the south before stalling and mixing out. Winds over central OK at 850mb are predicted to be rather weak and variable in the early part of the day. The storms/deep convection from the west will likely start to develop late afternoon/early evening at the earliest, requiring sfc/boundary layer heating...but once heating is sufficient to break whatever cap there might be, there should be plenty of energy and moisture to keep these storms going overnight. The highlight of the forecast was the development of some nice anticylonic flow expected to be in place by Wednesday, with the 700mb moisture fields moving to the east.

Two flight plans are being considered for tomorrow, with the final selection to be made after the morning’s weather briefing. Both are focused on the CLASIC-CHAPS campaign goal of providing information to evaluate the A-Train satellite flyovers (one of which is occurring in our area tomorrow afternoon). If conditions are good to the south, the G-1 (and other aircraft) will be deployed along a southerly part of the A-train path. A draft of this flight plan is attached (PPT 1MB) Alternatively, if conditions appear better to the north, then the G-1 (and other aircraft) will be deployed along a more northerly section of the A-Train path. (PDF 96KB) The above flight plans were still being tweaked as of the time of this writing so field folks should get the final versions tomorrow/Tuesday morning. We will NOT be making more measurements under conditions of deep convection…a little of this goes a long way.

Also on the ticket for tomorrow…PI’s for each of the instruments will be meeting at 9AM to review the preliminary data and cross compare observations made so far.

The CAPS probe.
(Large image)

17.June.07
For those who like rain, today's flight was great, with the G-1 encountering heavy precipitation starting shortly after the 11AM take-off and continuing through the return at 2PM. We wanted to test the CAPS cloud probe and test it we did (thanks again to Stephen Springston, Debbie Ronfeld and Yin-Nan Lee for getting the probe back to Ponca City yesterday!). All components of the CAPS system appeared to work as did the mass specs, the CVI instruments, etc. The G-1 had a very successful, albeit very wet, flight today.

The flight plan called for a wall of transects upwind of OKC with two downwind walls. Towering cu's throughout the area forced a number of diversions from the requested path. Pilots Bob Hannigan and Dick Hone were watching for thunderstorms on their onboard weather radar while the ground crew was watching the G-1 using newly written software that shows the G-1 path over a background defined by the latest NOAA weather radar image and visible satellite picture.

If you'd like to follow a G-1 flight in real time during one of our missions, contact Connor Flynn (connor.flynn@pnl.gov) for instructions on how to load the software used to produce the real-time G-1 flight/weather radar overlay for our June 15th mission. The G-1 flight path is shown by the green wall drawn over the planned flight path (shown in black). Background colors represent the strength of the radar return signal, with red indicating heavy precipitation from deep convective towers. All the excitement of being in the field without having to leave home!

The Aerosol Mass Spec team (Yin-Nan Lee, John Jayne, Liz Alexander and Matt Newburn) have started to look at the results from the June 15th flight, where the G-1 sampled at increasing distances downwind of OKC at a constant altitude of about 4000 ft MSL They found that an AMS sampling time of ~4 seconds appears to be capable of capturing the aerosol signal coming from the CVI inlet (which allows only cloud droplets into the sampling line). In the attached figure, provided by Yin-Nan, the top panel shows liquid water concentrations from the Gerber probe, which is a good indicator of when the G-1 was within a cloudy environment. In the bottom figure Yin-Nan has plotted the preliminary mass loading for sulfate (red) and organic (green) aerosols, and also indicated when the AMS was sampling from the CVI (cloud droplet) inlet and the isokinetic (the smaller interstitial aerosol) inlet. These numbers have not yet been corrected for the collection efficiency of the AMS, so take them with a big grain of NaCl. Note that the organics were greater than sulfate in the interstitial aerosol but reversed when sampling through the CVI.

Upcoming activities: tomorrow (Monday) is a down day, with the weather forecast to be marginal (at best). . .more afternoon thunderstorms, heavy rain, etc. We've sampled enough of that already.

Tuesday looks much more favorable and we hope to make two G-1 missions. OKC winds Tuesday morning are forecast to be light and variable, with fair weather cumulus throughout the area. We're planning to have one short (~2 hr) flight in the morning consisting of two constant altitude circumnavigations around OKC. If we encounter a lot of clouds we'll put the AMS on the CVI line. If the flight crew thinks there are fewer clouds, the AMS will be put on the isokinetic line. The afternoon flight will be coordinated with the other CLASIC-CHAPS aircraft to carry out an A-Train satellite evaluation. Final flight decisions will not be made until later Monday.

Moving from the scientific and logistical activities, we now turn to the day to day 'fun' of being in the field. While straightening up around the hangar Debbie Ronfeld came face to face with a live possum that had gotten stuck in a trash barrel. Both possum and Debbie are now doing fine.

16.June.07
The major expected event for today didn't happen: the CAPS probe that was supposed to be FedEx'd back to Greenwood Aviation was not delivered by FedEx. This probe is central to our cloud measurements and its absence a serious loss to the program. After many phone calls this morning by Debbie Ronfeld, FedEx found the probe and Stephen Springston drove to the Tulsa FedEx center to pick it up. Following this 1 ½ hour drive (one way), Stephen and John Hubbe did a series of ground tests and pronounced the probe to be in better shape than when it was sent in Friday. The CAPS probe is now back on the G-1 and should get a good workout tomorrow.

Absent the CAPS probe for most of today (Saturday), our planned joint-mission with the CIRPAS Twin Otter was cancelled. The goal of this joint flight was to study the time evolution of a cloud field at a fixed downwind distance from OKC and also to make measurements that might be used for an intercomparison of all the cloud instruments on both the CIRPAS Twin Otter and the G-1. This mission will probably occur later next week.

FrontPage headline on today's "The Oklahoman" Newspaper: "Okay, when will the rain stop?". An answer was given at the 10AM CLASIC-CHAPS weather briefing, which called for the rainy weather to clear out by Tuesday, with the promise of as many fair weather cumulus clouds to sample as we desire. The cyclonic system hovering over the area is slowly moving out and ridging should start to dominate the weather. Let's hope this forecast pans out.

We're planning a G-1/King Air OKC cloud sampling mission tomorrow (Sunday), hoping that tomorrow's rain forecast will again go bust. The lifting condensation levels are forecast to be slightly higher tomorrow than today which works in favor of our below-cloud sampling needs. Preliminary take-off time is 11AM, subject to change based on an updated forecast.

15.June.07
Thanks to those who crossed their fingers for a bust forecast. . .it worked. The morning forecast discussion (5:48AM CDT) included statements such as "FLASH FLOOD WATCH HAS BEEN EXTENDED. . ." WITH BANDS OF HEAVY T-STORMS CONTINUING TO ROTATE . . .ISOLATED RATES APPROACHING OR EXCEEDING 2 INCHES/HR." While the rain was quite heavy throughout last night, skies started to clear by late morning/early noon and the G-1 launched at 2PM CDT. The flight plan (included in yesterday's update) consisted of constant altitude transects downwind of "Oak City" (local parlance for Oklahoma City). Not only did all the instruments work well, but the earlier problem of excessive cabin heat did not appear. This may have been in part due to the somewhat cooler temperatures today but it was also likely a result of the engineering efforts implemented by John Hubbe, Betsy Anderson and Stephen Springston. The NASA King Air was not able to join the G-1 today due to a mechanical problem necessitating flying the King Air to Wichita for repairs. The King Air crew had the added bonus of being rerouted to make way for Air Force One.

Droplet Measurement Technology (DMT) received the CAPS probe, found the problem that necessitated its (second) return to the factory and will be sending it back to Ponca City tonight with expected delivery tomorrow morning.

The flight planning software started by Rahul Zaveri has morphed into quite a creation. The attached PowerPoint file contains today's flight plan superimposed on a Google Earth image. Pretty cool, eh? But John Ogren and Conner Flynn couldn't resist adding another layer to this figure. The colored background shows real time weather radar with the position of the G-1. We can now compare the planned G-1 track with the most recent radar information, greatly helping with the last minute go/no-go decisions. Building on the earlier work of Rahul and Craig Straight, the ground crew can also follow the G-1 position as it moves over a background map showing real-time radar data.

Tomorrow's weather shows a mesoscale convective system moving into the area overnight, with a number of vorticity maxes producing rain throughout the area. Nonetheless, we have filed a flight plan. As of Friday evening, plans call for repeated sampling within one vertical box (defined as low- and high cross-wind transects connected by vertical spirals) by the G-1, and concurrent sampling within a smaller vertical box by the CIRPAS Twin Otter. These are preliminary plans and may change with discussions tomorrow morning. The scientific goals of this mission are to characterize the time evolution and spatial heterogeneity of a cloud field at a fixed distance downwind of OKC. The results may also be useful for a cross-comparison of the refurbished CAPS probe on the G-1 with the CAPS probe on the CIRPAS Twin Otter. Expected take-off time will be late afternoon so to let Stephen Springston do bench tests on the CAPS probe before reinstalling it on the G-1.

Recognition for a job well done: the FAA Air Traffic Controller's we've been working with asked if they could use today's flight plan as an example of what they want from others requesting special activities. Credit for this success is due to Rahul Zaveri who designed the software package being used for all our flights.

14.June.07
Another down day for the G-1 today as a result of the rain forecast for throughout the area. There was indeed heavy rain over Oklahoma (in excess of 4" overnight, just west of Ponca City), although at the time of this writing the weather radar is showing only scattered showers over Oklahoma City with broken or overcast skies throughout the state.

Tomorrow's forecast includes deep convection to the east and to the west of central Oklahoma, with only stratiform rain over the Ponca City/Oklahoma City area. However, noting that today's steady rain forecast did not materialize, we are filing a flight plan for tomorrow hoping for a bust in the forecast precipitation.

A flight plan has been filed with the FAA for tomorrow (Friday). We'll make a final go/no-go decision by 12PM CDT based on echoes shown by the weather radar. Our plan calls for a set of low altitude (3500 ft MSL) transects at increasing downwind distances to the northwest of Oklahoma City. Absent the CAPS probe (see below), we're hoping this low altitude flight will consist mostly of below-cloud observations. We are requesting 6 constant altitude downwind transects with a return path that goes over the ARM Southern Great Plains site, where we will make a spiral up to 8000 ft, followed by a return to Ponca City. The NASA King Air will fly overhead for most of the flight, pulling off towards the end to join the CIRPAS Twin Otter which will make a similar overflight of SGP.

The science driver behind this flight is to characterize the CCN by number and composition (with the AMS) at increasing distances downwind of OKC. A spiral over SGP is to provide observations against which the SGP surface measurements can be compared, and to test the pressure sensitivity of some of the instruments. We're hoping to get into clouds as we fly from Ponca City to OKC so we can do additional instrument testing on the CVI line.

The CAPS probe is making its second trip back to Droplet Measurement Technology (DMT) for repair. Stephen Springston was told we should have this instrument back in the field this Saturday, before the forecast improvement in weather starts to kick in late this weekend. This instrument is crucial for interpreting cloud measurements. Its absence was a major factor in our decision to focus tomorrow's flight on below-cloud observations.

13.June.07
The G-1 was down for scientific flying today as a result of the mechanical problems noted earlier. However, thanks to the heroic efforts of our pilots and a mechanic from Houston, the G-1 is already back in action and had a successful test flight today. Some of the scientists leaving the hangar late last night saw the G-1 suspended from jacks, with all wheels off the ground and spinning freely. Quite a sight for those of us who only see this during take offs.

Today's weather was dominated by a closed cyclonic circulation system that allowed any surface convection to boil up, producing widespread thunderstorms and rain between Ponca City and Oklahoma City. The cut-off low causing these problems looks like a bullseye drawn over Oklahoma, from the surface to 500mb.

Tomorrow's/Thursday's weather looks to be more of the same, with a high forecast probability of precipitation throughout the area, coming as either widespread stratiform or locally intense convective showers. The met models show this cyclone slowly filling over the next few days, moving to the south and being out of our area by Friday afternoon or Saturday. As a consequence of this weather feature, no research flight is planned for tomorrow. If tomorrow's forecast for Friday offers any encouragement, we will file for a short (~<2 hrs) Friday afternoon flight. The objective of this possible Friday afternoon flight would be to shake down some instrument problems that arose during our June 11th flight. We're hoping conditions allow us to make a longer research flight Saturday morning.

Carl visited the CHAPS surface site in Edmond, just north of Oklahoma City, where a radar profiler, radiosonde system and aerosol rack are in place. Many thanks to Will Shaw/PNNL for coordinating the set up of the ground station. Misha Pekour/PNNL, Rich Coulter/ANL and Tim Martin/ANL all reported 'seeing' the OKC plume on a regular basis and said that all instruments working as expected. One curious feature they noted was that the aerosol observations indicated a strong aerosol plume on June 11th concurrent with when the G-1 was sampling overhead, although the plume signal was very weak for the G-1. Rich observed that the profiler indicated considerable directional shear over the area, which may explain why the ground based instruments saw the plume but those onboard the G-1 did not. These observations are shared simply as something interesting noted in the field and may be subject to revision with closer analysis.

Last, but certainly not least . . .all of the field crew was sorry to see Larry Berg depart from the campaign to resume activities at the homefront. Larry worked with Misha, Rich and Tim to set up the ground site prior to the G-1 arrival in Ponca City, and then stepped into the role of aircraft coordinator during the first week of the campaign, working with the pilots and FAA to set up a communication protocol for both CHAPS and CLASIC. This was a non-trivial job done under stressful conditions. All of us in the field extend a sincere 'thanks' to Larry for doing a great job in getting the campaign off the ground!

12.June.07
The King Air had a very good flight today, sampling under the A-Train satellites . . .no high cirrus to interfere with measurements.

G-1 is down for hydraulics repairs.

11.June.07
Great conditions today for aerosol sampling. The King Air and the G-1 carried out a coordinated flight upwind and downwind of Oklahoma City, with the HSRL on the King Air flying directly over the G-1. Unfortunately, the G-1 experienced a leak in the hydraulic system. It is expected to be down for a day or two until the problem is fixed. Fortunately, the down-time is expected to correspond with a period of convective weather conditions not suitable for sampling.

A media event was held in the morning, and a handful of media attended, as well as former and current state senators.

10.June.07
Flights today were scrubbed following the morning weather briefing. The Norman radiosonde showed a weak inversion that would not cap any convection that started later in the day. All flights were cancelled due to the development of this situation.

A new Total Sky Imager has been installed at the University of Central Oklahoma. This instrument provides a time series of hemispheric sky images during daylight hours and retrievals of fractional sky cover for periods when the solar elevation is greater than 10 degrees. It was provided by the PNNL Atmospheric Remote Sensing Laboratory, and will be used to quantify the extent of cloud cover when the G-1 is flying over the Oklahoma City area.

The Total Sky Imager is operational at the University of Central Oklahoma.

9.June.07
Today marked the beginning of "Flynn's Field Files." This "daily log" is provided by one of our crew, Connor Flynn, and is geared to give a general audience the flavor of what happens during a field campaign like CHAPS. He plans to describe not only his activities, but introduce the rest of the team and explain their roles as well. The link is: http://www.pnl.gov/atmospheric/programs/asp.stm

7.June.07
Today PNNL issued a press release about the CHAPS and CLASIC field campaigns—see http://www.pnl.gov/news/release.asp?id=253 for more information.

6.June.07
There were no aircraft operations today.

4.June.07
Today PNNL issued a news advisory about an event that will be hosted at the Ponca City Airport for media and distinguished guests on June 11. See http://www.pnl.gov/news/release.asp?id=252. For more information, contact Lynne Roeder, 509-372.4331.

21.May.07
Office and hangar arrangements were sent out last week, with PowerPoint files showing floor plans and office assignments. As noted in the last update, Bev Johnson (beverly.johnson@pnl.gov) is working with Chuck Greenwood/Greenwood Aviation and PNNL's Debbie Ronfeld (debbie.ronfeld@pnl.gov) to make sure internet drops, work benches, chairs, desks, etc. are available for all who need them. Contact Bev or Debbie with questions or concerns.

Carl will be on travel May 23 - May 29th, returning on May 30th, and will check e-mail from time to time. Alternatively, please leave messages with Ruth Keefe (509-372-6163) who will be in touch with Carl.

16.May.07
In the first week of May, the LANL team (Claudio and Dubey) worked closely with John Hubbe to deploy two photo-acoustic instruments on the CVI and the main isokinetic inlet. Also here that week were Yin-Nan Lee, Liz Alexander, and Matt Newburn, installing the AMS and PTR-MS, and Betsy Andrews, tuning up the CVI. The team test flew the compliment of gear on 5/3 and 5/4. Dubey reports that two test flights showed the acoustic noise on the CVI inlet to be low and within acceptable limits. That's the good news. Unfortunately, the noise on the main inlet was very high. John is working on modifying the flow sampling on this inlet, and Claudio and Dubey are thinking of other ways to damp this whistling of the inlet. The new schemes will be tested during followon test flights. Contact Dubey for more details.

During the week of May 7, Stephen Springston, Gunnar Sennum, Jason Olfert, and Jian Wang came to the G-1 hangar to install gas-monitoring gear, networking gear, the TSEMS and the new FIMS, and did cal work on the CAPS and PCASP probes. Test flights were conducted on 5/13, 5/14, and 5/15. On May 15, the SATCOM capability (data downlink and chat) was tested.

The CHAPS flight plans were presented to the CLASIC field team during a planning meeting at the Greenwood Aviation hangar in Ponca City, May 9-10. Rich Ferrare and Carl Berkowitz represented the CHAPS component of the meeting. In addition to the G-1, there will be 7 other aircraft flying throughout the campaigns. Safety protocols and procedures were discussed. Mark Miller/CLASIC also led the group through a discussion of a number of weather events from last summer, followed by a recommendation of flight plans for the CLASIC and CHAPS aircraft. Only one 'mission' was less than optimal based on the outcome of the forecast conditions for these historical events. Perhaps the biggest consideration at this point is how to link the A-train underflights with one of our Oklahoma City missions.

Greenwood Aviation will be our Field Base of Operations for CHAPS. Bob Hannigan and John Hubbe have finalized hangar space. We'll have a central conference room for twice-daily weather briefings (6:30AM, 1PM) and a number of offices that are now being assigned. Bev Johnson (beverly.johnson@pnl.gov) is working with Chuck Greenwood and PNNL's Debbie Ronfeld (debbie.ronfeld@pnl.gov) to make sure chairs, desks, etc. are available for all who need them. Debbie hopes to send out floor plans with names matched to desks within the next few days. If you can't wait for this information, please contact Debbie. She can give you the latest update. The group will be notified as plans become finalized.

Last, an update from Will Shaw/PNNL who's been working with Rich Coulter/Argonne in getting the CHAPS surface site up:

"During the CHAPS campaign, ASP will be supporting the collection of meteorological and aerosol data at a ground site (approximately 35º 44' 04" N, 97º 28' 49.4" W) just north of Edmond, Oklahoma. Mr. Bob Brentlinger, who is developing part of his farm as Brentlinger Industrial Park, has agreed to allow us to locate our equipment on his property for the campaign. The area is rural, but within a few miles of the Oklahoma City urban area.

PNNL will provide radiosonde launches (up to five per day when the G-1 flies) and particle characteristics from a PCASP, a PSAP, nephelometer, and condensation particle counter. Argonne National Laboratory will provide radar measurements of the winds above the surface and profiles of aerosol backscatter from a micropulse lidar. Participants from Visidyne plan to operate a SAM (Sun and Aureole Measurement) sensor to measure cloud optical properties at the site, and Scot Martin's group from Harvard will be accommodated to operate their mass spectrometer.

PNNL is also planning to operate a Total Sky Imager at a nearby location (because of the requirement of internet access for the instrument). Those arrangements are being completed."

Mandreva Dubey (top) and Claudio Mazzoleni (middle) from Los Alamos National Laboratory check the readout from two photo-acoustic instruments they added to the counterflow virtual impactor and the main isokinetic inlet on the G-1 aircraft. Yin-Nan Lee (foreground), verifies the operations of the aerosol mass spectrometer provided by Brookhaven National Laboratory. (Large image)

Claudio Mazzoleni (foreground) monitors the status of the photo-acoustic instrument during a test flight. Betsy Ogren (background) is happy with the results she sees in the wide variety of instruments installed for NOAA.
(Large image)

30.APR.07
This week John Hubbe is working with Dubey and his team to install the Los Alamos Photoacoustic Instrument for measuring aerosol extinction, scattering and absorption. Yin-Nan's Aerosol Mass Spectrometer has also arrived at PNNL and Liz Alexander will be working on its installation. Others from Brookhaven will be coming to Tri-Cities next week to continue instrument installation.

19.APR.2007
A revised 'Calendar of Activities' has been posted.
Thanks for reviewing it and getting any changes/revisions to John Hubbe as soon as possible.

Will Shaw and Rich Coulter have identified three candidate surface sites during their visit to Oklahoma earlier this week. Details will be posted on the webpage in a day or so.

Note that the webpage "Protocol and Flight Plans for the G-1" is being revised. The new version of the flight plans will go into much more detail than what's presently posted and will also include additional flight plans, the distribution of hours for the various flights and a schedule of daily activities (weather briefings, flight times, debriefing times, etc.).

John Hubbe/PNNL and Betsy Andrews/CIRES onboard the G-1 aircraft in Pasco, during the installation of the CVI probe on the G-1 aircraft. Photo courtesy of Larry Berg.
The external part of NOAA's Counterflow Virtual Impactor, recently mounted on the G-1 aircraft. The upper inlet is the CVI probe, the lower inlet is the PNNL isokinetic inlet. Photo courtesy of Larry Berg.

15.MAR.2007
Status of surface site: Will Shaw is working with Rich Coulter of Argonne National Laboratory to locate and set up a surface site for measurements just north of Oklahoma City. This will be the location for a radar wind profiler and aerosol backscatter lidar from Argonne, and an aerosol rack, a total sky imager, and a radiosonde system operated by PNNL. We are very fortunate to be receiving support from The Oklahoma Climatological Survey in locating these sites, and gratefully acknowledge the support from Jeff Basara, the Director of Research for OCS. Will is also working with Scot Martin of Harvard's School of Engineering and Applied Sciences to deploy a time-of-flight Aerosol Mass Spectrometer (ToF-AMS) at the site. Dates and logistics for this instrument are being worked out. Check with Will for updates and questions.

Status of instrument installation on G-1: Betsy Andrews, Research Scientist with the Cooperative Institute for Environmental Science (CIRES) at the University of Colorado, and John Hubbe/PNNL have completed the installation and testing of the NOAA counterflow virtual impactor on the Gulfstream aircraft. The result of this five day project will give the G-1 the capability to separate cloud droplets from interstitial aerosol, and to send the droplets through a heater/evaporator system to allow for measurements of the residual aerosol mass for light scattering, light absorption, size and composition (through a ToF-Aerosol Mass Spectrometer). Check with John for updates and questions.