In spite of a situation in which convection was becoming more widely

scattered and decreasing in intensity, it was decided to continue with

plans to have a coordinated flight between the DC8 and the Convair.

The plan was to have the DC8 land about sunset (this was done) and the

Convair to remain aloft to cover the time of the TRMM overpass at 0828

(this was not done because of the lack of suitable echoes).

From about 0320-0510, the DC-8 worked a group of echoes well east of

Kwaj. Starting at 39Kft, stepping down to 36 and then 33Kft. The line

of cells was oriented about 295-105 degrees. The DC8 executed a line

pattern which was shifted slightly to the south as time went on. After

4 passes along 3 flight lines (parallel and close to one another) the

pattern was changed to a bowtie fashioned out of a short S-N line

through a roughly circular blob. ARMAR and AMPR saw some good cells

during the middle of the period, but the system collapsed rapidly after

0500. Houze and Zipser seriously considered sending both aircraft home

at that point. However, to preserve the first chance for coordination

between two KWAJEX aircraft and the Ops Center, we sent both aircraft

to the only target available, a short line of small cells south of

Kwaj.

At or before 0524, Line 6 coordinates along the cumulus line were

passed to both aircraft, along with a suggested start time of 0529 (EZ

note=8A.these times may be off by several minutes). The two a/c then

coordinated their tracks such that they flew the same line, and arrived

at the center point within a few minutes of one another. Some of the

small cells had heavy rain showers (:AMPR and ARMAR from 33Kft). After

several passes along the line, the DC8 departed for Kwaj at about 0625,

while the Convair completed their systematic staps up in altitude until

cloud top at about 19.5Kft before returning to Kwaj.

_____________________________________________________________________________

DC-8 Mission Scientist Report for 30 July, 1999 (Julian Day 211)

__________________________________________________________________________

A mission was flown to sample precipitation within range of the

S-BAND radar. The DC-8 was in the air at 0300 UTC and flew alone for

about 2 hours. The DC-8 began by climbing to 37,000 feet to set up on

a line between 8 degrees, 56 minutes North latitude, 168 degrees, 9

minutes East longitude and 8 degrees, 31 minutes, 169 degrees, 10

minutes East longitude. The DC-8 flew through patches of light cirrus

on this line. The CPI and CPP both reported particles size between 100

- 300 microns. The Scanning HIS observed cloud top temperatures of

approximately 260 Kelvin at the center point of this line. The ARMAR

and AMPR reported rain observations on the southeastern portion of this

line.

The DC-8 ascended to 39,000 feet for a short period, but then

descended to 33,000 feet around 0400 UTC. Several passes were set up to

sample precipitation in the general vicinity of 8 degrees, 30 minutes

North latitude and 168 degrees, 40 minutes East longitude. Coordinated

maneuvers were conducted with the University of Washington Convair after

about 0500 UTC. The most intense convection sampled during the entire

mission was in the vicinity of 8 degrees, 7 minutes North latitude and

167 degrees, 48 minutes East longitude. The AMPR observed an ice

signature corresponding to a 205 Kelvin brightness temperature

depression in the 85.5 GHz. At approximately 0615 UTC, the DC-8

finished data sampling and returned to the Kwajalein air field.

Overall, the mission was a reasonable success. The communication

between the TRMM Operations Center, the DC-8, and the Convair seemed to

be working fairly well. All research instruments onboard the DC-8

appeared to perform well, but closer examination of the data are still

pending. The DC-8 mission length was 3.9 hours with 100 research hours

remaining for further use.