KWAJEX Operations Director Report Number 1

U.S. Army Kwajalein Missile Range, Kwajalein Atoll, Marshall Islands

Period: 24 July - 6 August 1999

Operations Director: Professor Robert Houze

This is the first report to be issued during KWAJEX by the Operations Director. These reports will be issued each time the Operations Director changes. The next two Operations Directors will be Professors Tom Wilheit and Eric Smith.

Project Office

The KWAJEX Project Office provides administrative support for the program. Steve Hipskind has been the Project Manager in charge of this office for the first part of the project. Wendy Dolci is presently acting as Project Manager. She will be followed as project manager by Mike Craig and Thomas Kalaskey. Finally Steve Hipskind will return for the last two weeks of the project. The Project Office has been helpful in interfacing with KMR on a wide variety of practical issues including housing, shipping and transportation around Kwajalein and to the outer islands.

KWAJEX Operations Center

Project Science Coordinator, Professor S. Yuter, directly supports the Operations Director and is acting Operations Director whenever the Operations Director is unavailable. In addition to science activities, she interfaces with the Kwajalein Missile Range (KMR) on communications and air traffic control issues. Under Sandra’s leadership a well organized multi-purpose Operations Center is functioning 24 h a day. The Operations Center Staff monitors the radar data collected at all times, with special attention to TRMM overpass times, aircraft flight times, and coordination with the ship radar. They take cloud photographs and collect Joss-Waldvogel disdrometer data at the Operations Center site. They support the Aircraft Mission Coordinator and the DC-8 Mission Coordinator in real time during flights. They do this by providing three dimensional processed radar data on Zebra with real-time flight tracks superimposed on the echo pattern. The flight tracks are updated every five seconds from each aircraft. Carl Sweetland has designed an excellent radio communications network that keeps the Operations Center in close communication with all 3 aircraft, the NOAA Ship Ronald H. Brown, and KMR communications. The Operations Center prepares post flight summaries of each aircraft mission. These summaries are used to lead off the 0800 LST daily planning meeting by debriefing the previous day’s mission. These summaries include a time series of radar images with the flight tracks of all participating aircraft superimposed. The Operations Center also maintains a website for the project that contains: the mission summary images, written scientist reports for each mission, daily instrument status, hourly radar images, a table of overpass times and maps of the geometry of each pass over Kwajalein, the radar images for each overpass, digital cloud photographs for each day of the project, and other information. This website is constantly updated and made available to all the project investigators on a local network. A subset of the website is being mirrored on a mainland site http://www.atmos.washington.edu/gcg/MG/kwajex/. Anyone may access this site to track the progress of KWAJEX.

Surface sites

The Surface Sites Coordinator for the first time period is Dr. Jeff Halverson. Dr. George Huffman and Dr. Brad Ferrier will serve as coordinator during subsequent parts of the project. Coordinated extra sounding releases (3 hourly) have been made by the designated sites in support of aircraft missions. Quality control shows Woja and Lae soundings to be of good quality. The sounding data from Meck have been intermittent as a result of equipment problems. The Ronald. H. Brown soundings have had intermittent losses of the wind data for reasons not yet determined. The tethersonde system under the direction of Professor Mike Garstang was knocked out and damaged by an unusually strong gust. The KMR has provided rapid assistance in repairing the damage and in building a temporary hangar to protect the system from future strong wind events. The tethersonde is back in operation. Most of the raingauges and APL disdrometers are up. The Kwajalein video disdrometer arrived non-functional and is down indefinitely. The profilers on Legan are both operational. There have been intermittent problems with data transfer via satellite to Boulder, but archival of data on site has been uninterrupted.

Forecasting support

Weather briefings at our daily aircraft mission-planning meeting have been supplied by Aeromet, which has so far done an outstanding job of providing weather forecast guidance in a very difficult forecasting regime. They also operate the S-band radar and provide sounding support.

NOAA Ship Ronald. H. Brown.

After a delay waiting for repair of the C-band radar, the Brown went on station on 28 July. The radar initially had an incorrect pulse-width setting. The data collected from 28 July - 1 August will require correction of the header information before it can be analyzed. The Operations Center is collaborating with the ship chief scientist, Dr. Rob Cifelli, in comparing data from the C-band radar on the Brown with the S-band Kwajalein radar operated by Aeromet. The ship radar is systematically ~5 dB higher than the S-band. The cause for this discrepancy is not yet known. Dual-Doppler radar data combining the C-band ship radar and S-band Kwajalein radar have been collected in one aircraft mission in some rather small convection. Colleen Leary will be Chief Scientist on the R.H. Brown for the second half of the project.

Aircraft Missions

The Aircraft Mission Coordinator until midway through the project is Professor E. Zipser. Professor M. Biggerstaff will replace him in the second half of the project.

The aircraft program has had some serious (hopefully) temporary problems with the UW Convair 580 and UND Citation aircraft, and these are being addressed at the time of this writing. The main problems are a radar failure on the Convair and radio failures on the Citation. The repairs for some of these problems require parts to be shipped from the mainland. Presently, the Convair is limited to flying in convection only in the daytime and only in stratiform precipitation at night. Before the radio failure on the Citation, it flew in two coordinated aircraft missions. The DC-8 has had no problems up to now.

Despite the limitations on the use of the Convair and Citation, 7 aircraft missions have so far been conducted. These include a test flight for the Convair, a test flight for the Citation, and an aerosol flight for the Convair. The Convair has obtained microphysical data precisely coincident with 2 TRMM overpasses. One of these was a coordinated flight with the Citation. Both overpasses were at night and therefore did not include the DC-8. The Convair has flown two daytime coordinated flights with the DC-8. One of these was in the eastern dual-Doppler lobe of the ship C-band and Kwajalein S-band radars. These flights have generally emphasized raindrop-size distribution sampling by the Convair and remote sensing and ice particle sampling by the DC-8.

Using the Operations Center’s tools described above we have been nearly 100 per cent successful in locating the aircraft horizontally in the most preferred radar echoes and in coordinated missions the aircraft have coordinated their flight lines with pinpoint accuracy. In the vertical, the positioning of the planes has been less than optimal for KWAJEX objectives. The DC-8 has been flying primarily at flight level temperatures of –30 to –60°C, as planned. At these levels, they generally have remained out of any but the weakest convection, mostly in stratiform ice cloud. The AMPR and ARMAR systems emulating the TRMM PR and TMI appear to be working well. The Convair has obtained a lot of data at flight levels where the temperature is > 0°C. They have extensively sampled the raindrop size distribution. They have had a more limited number of flights at temperatures < 0°C. They had some problems with the CPI when they were sampling in the ice layers. The Citation has made one flight in which they collected data at a fairly wide range of temperatures < 0°C. Overall, however, there has been relatively little data collection in the 0 to –30°C levels. Since data at these levels are critical to achieving KWAJEX objectives, the next few weeks should see an emphasis on obtaining data at these levels, especially by the Citation. Since the Convair has the AMMR (upward looking microwave radiometer) as well as CPI it is especially important that this aircraft make runs just below, at, and just above the 0°C level, up to about –10°C or so. This cannot be accomplished until the pressurization is repaired. Also convective sampling during night time overpasses will be highly restricted until the Convair radar is fixed.