Research flight # 3: 4 July 2005
Route of flight: Coulter Field – Houston area – Galveston - Coulter Field
Cheyenne research time: 15:21 – 18:49, 20:14 – 21:14; 4 hr 28 mins
Cheyenne research time to date: 10 hr 8 min
Objectives:
1. Conduct pollution plume reconnaissance missions in the Houston area.
2. Conduct cloud penetrations at cloud base.
Pilot: Gary Walker
Instruments operator: Duncan Axisa
Flight scientist: Duncan Axisa
Field Meteorologist: Dr. Don Collins, Crystal Reed
Mesoscale discussion:
Soundings indicate that the atmosphere is drier and more capped than yesterday. A few TCU
developed in the area of study with daytime heating.
Weather conditions:
Sky conditions at take off in Coulter Field were few to scattered shallow stratocumulus. The
clouds became more convective in the Houston area with a few towering cumulus. Once again,
the cloud bases lifted were the pollution plumes seemed to be present.
Flight planning:
The main objective of this flight was to explore how the CCN and DMA measurements would
characterize any pollution plumes in the Houston area, and how the CCN are related to the cloud
droplet concentrations. It was planned that the aircraft would fly to Navasota under the cloud
bases, open a flight plan at Navasota, conduct cloud base penetrations along a route from
Navasota east, reverse course and conduct CCN/DMA measurements below the cloud bases. The
plan was then to fly towards the Galveston area, close to the coast to conduct CCN
measurements preferably below cloud base.
Preflight:
The CCN counter was operated at a supersaturation of 0.3 during the duration of the flight. The
TDMA was operated in DMA mode with the RH set at 30%.
Flight report:
The research aircraft departed Coulter Field at around 15:30. At 15:36 the aircraft was straight
and level at an altitude of 2700 feet with very shallow stratocumulus just above the aircraft
altitude. The wind at this level was 230 at 19.6m/s, temperature 24/21 and RH 79%. The CCN
counts were around 250 to 400/cc with a mode around 4µm.
Coulter Field
Conroe
Houston
Gulf Coast
Altitude profile and Flight track
Notes were taken for the duration of the flight:
15:43 – the aircraft climbs to 3000 feet.
15:45 – the aircraft is now over the Navasota VOR. Stratocumulus streets seem to be aligned
north and south.
15:47 – climbing to 4000 feet. The cloud bases are at 3900 feet.
15:50 – the aircraft is now level at 4365 feet, about 600 feet above the cloud bases. Various
cloud penetrations follow. At 15:55, it is observed that the CDP concentrations appear to be
higher (around 1000/cc) at a location 10 miles west of Conroe. This location coincides with
where the CCN were observed to increase yesterday. The cloud bases also appear to be higher at
this location. It is observed at 16:02 that the CCN out of cloud is around 1000/cc.
16:05 – the aircraft turns west back to Navasota. Again, at 16:10, the CDP concentrations appear
to be on the high side (900/cc). Cloud bases once again appear to be higher since the aircraft is
now penetrating 200 to 300 feet above the bases and the ground is almost visible during the
penetrations. A decision is made at this point that the aircraft should backtrack to this location at
a higher altitude to penetrate the middle of the cloud.
16:18 – CCN concentrations are 2500/cc out of cloud
16:20 – the aircraft turns and climbs 500 feet with penetrations following on the track east.
Similar conditions are observed with CCN close to 2000/cc out of cloud and droplet
concentrations up to 1400/cc in 3 to 4m/s updrafts.
16:35 – the aircraft descends to 3000 feet to get below the cloud base and turns west direct to
Navasota to measure CCN on the same track. The aircraft is straight and level at 3100 feet.
Flight conditions become bumpy.
16:46 – CCN increase to around 3000/cc. It is decided that a track parallel to the previous should
be flown to measure CCN south of the previous location. Winds are now 200 at 6m/s.
16:56 – CCN increase again to 8000/cc.
17:02 – the aircraft is vectored north to avoid the approach at Houston International Airport. The
aircraft is then cleared back on track at 17:11 to proceed southbound. Here cloud bases are at
3400 feet. A series of cloud penetrations follow, with droplet concentrations above 1000/cc
becoming more frequent in the updrafts. Penetrations are conducted at about 300 feet below the
top.
17:22 – the aircraft is over the coast.
17:24 – the aircraft turns back north a little further west than the previous track.
17:26 – the aircraft is now flying over the several refineries. Several cloud penetrations are made
500 feet above the cloud base with the ground not visible. Droplet concentrations are between
700 and 1200/cc.
17:35 – the aircraft is turned east at an altitude of 3000 feet.
17:37 – the flying conditions become bumpy at 3400 feet.
17:39 – the aircraft I snow heading south towards Galveston. At 17:51, the CCN are noted to
increase to 4500 and 5500/cc above the water with winds from 165 at 5m/s. It is decided that the
aircraft should reverse course (17:54) to confirm these measurements. CCN do increase to
2000/cc (17:57). At 17:58, the aircraft turns again towards Galveston. At 18:01, counts increase
to 5000/cc again.
18:04 – the crew decide to profile a cloud vertically from 3000 feet to 7000 feet. Penetrations are
made every 1000 feet through the middle of the cloud. The cloud top was estimated at 7500 feet
and the cloud was medium hard and convective.
18:15 – the aircraft descends to 3000 feet. CCN are very low during the fast descent. Clouds are
penetrated on the way down. Clouds have maritime concentrations at this location.
18:30 – cloud base is measured at 2000 feet. CCN below cloud base are measured at 200-300/cc.
The aircraft flies along the coast and then turns for landing in Galveston. Wind is 180 at 8m/s at
2000 feet AGL.
18:45 – landing in Galveston
18:49 – shutdown
The crew stops for a late lunch break. It is decided that a direct flight from Galveston to Coulter
Field at 1500 to 2000 feet AGL would gather supplementary CCN/DMA data during the ferry
flight.
20:14 – engine on
20:24 – Aircraft is straight and level at 1500 feet. Wind is 170 at 10m/s.
20:34 – CCN increase to 2000/cc.
20:46 – aircraft climbs to 2000 feet.
20:50 – CCN increase to 3000/cc.
21:14 – landing in Coulter Field and engine off.
Camera # 62 and 63
Impressions:
CCN counts consistently appear to be high in the 2 same locations. The cloud bases also appear
to be higher at these locations. Cloud penetration data seems to suggest that the droplet
concentrations are higher in these locations. Careful analysis is required of this data to confirm
these initial impressions.