Research flight # 12: 23 July 2005
Route of flight: Coulter Field – Navasota – Conroe – Desata - Conroe – Navasota – Conroe –
Desata – St. Jacinto Monument – I10 Corridor - Sealy – Navasota - Coulter Field
Cheyenne research time: 15:15 – 18:05; 2 hr 50 mins
Cheyenne research time to date: 36 hr 50 mins
Objectives:
1. Conduct pollution plume reconnaissance missions upwind and downwind of the Houston area.
Pilot: David Prentice
Instruments operator: Duncan Axisa
Flight scientist: Duncan Axisa
Field scientist: Crystal Reed
PI: Dr. Don Collins
Mesoscale discussion:
Convective activity has been scattered in nature during this period with a line of thunderstorms
developing along the I10 corridor, which happened to be along the route of flight during the time
the aircraft was in that area. Convective temperature was around 90, and reached around noon.
Weather conditions:
Sky conditions at take off in Coulter Field were broken cumulus with cloud base at 2100 feet,
temperatures 31.4/24.8, RH 67 and atmospheric pressure1006.4mb. Conditions at Houston
International Airport was the following (local time):
Date
Time
Wind
23
17:53
E 12
23
16:53
23
Sky conditions
Temp
Dew
10.00 Partly Cloudy
FEW045TCU SCT250
89
74
1015.9
E9
10.00 Partly Cloudy
FEW045TCU SCT250
91
75
1016.2
15:53
E 10
10.00 Partly Cloudy
FEW045 SCT250
91
75
1016.9
23
14:53
E 10
10.00 Partly Cloudy
SCT038 SCT250
90
74
1017.5
23
13:53
S6
10.00 Partly Cloudy
SCT040TCU SCT250
89
74
1018.1
23
12:53
N6
10.00 Partly Cloudy
SCT035TCU SCT250
88
73
23
11:53
Calm
10.00 Partly Cloudy
SCT031TCU SCT250
89
73
1019.2
23
10:53
SW 3
10.00 Mostly Cloudy
BKN022 BKN250
85
75
1019.7
23
09:53
Calm
10.00 Partly Cloudy
FEW020 SCT250
84
76
1019.7
23
08:53
E3
10.00 A Few Clouds
FEW250
80
74
1019.7
23
07:53
Calm
10.00 Partly Cloudy
FEW030 SCT100 SCT250
77
72
1019.0
23
06:53
NE 3
10.00 Partly Cloudy
SCT100 SCT250
74
72
23
05:53
NE 3
10.00 Partly Cloudy
SCT100 SCT250
74
72
Flight planning:
Vis
Weather
Tmax Tmin Pres (MSL)
91
75
74
74
1018.7
1018.7
1018.5
The main objective of this flight was to measure the background aerosol and CCN concentrations
north and south of the Houston area under southerly surface winds.
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 15:29. Cloud bases were measured at 2100 feet at
15:32 after takeoff. Tops were observed to reach altitudes above 10000 feet. At 15:33 the aircraft
was straight and level at an altitude of 3000 feet. Winds at this level were 280 2m/s. At 15:40,
the aircraft was climbed to 4000 feet by air traffic control at Navasota. At this location, clouds
appear to be broken cumulus and towering cumulus. Various cloud penetrations follow.
Coulter Field
In & out of cloud
Conroe
Navasota
Below cloud base
Sealy
Houston
Flight track and altitude profile
CCN counts over the duration of the flight
Notes were taken for the duration of the flight:
15:51 – the aircraft descends to 3000 feet.
15:53 – the aircraft is now over the Conroe airport.
15:57 – the pilot reports water on the windshield during a penetration when the CDP records
1.25 g/m3
16:02 – the aircraft adjusts altitude to 2400 feet to penetrate clouds closer to their bases. Clouds
have become less convective in this area. Wind is measured at 260 3.5m/s.
16:08 – the aircraft is now at the Desata VOR and turns back west.
16:15 – the aircraft is climbed to 3000 feet by ATC. Winds are light and variable.
16:30 – winds are now measured at 160 4m/s.
16:38 – turning east at Navasota and descending
16:40 – the aircraft is straight and level at 2000 feet. Wind at this location is 250 3.6m/s.
16:50 – CCN increase to 4500/cc. This could be due to a brush fire that was burning in the
vicinity.
16:52 – the aircraft is now at the Conroe airport and CCN increase to 2500/cc at 16:55.
17:02 – CCN increase to 3000/cc
17:07 – the aircraft is now at the Desata VOR and turning 190 degrees towards the St. Jacinto
monument.
17:11 – wind at this location is 035 at 2.9m/s
17:13 – the aircraft descends to 1500 feet. Wind is light and variable from the east.
17:21 – the aircraft is now at the St. Jacinto monument. Thunderstorm showers are lined up
along our route on I10.
17:22, 17:23, 17:24, 17:27, 17:29 – the aircraft is in rain showers briefly
17:32 – the aircraft climbs to 2000 feet
17:36 - CCN increase to 2800/cc.
17:38 – the aircraft is a Sealy intersection
17:44 – winds become 090 at 19m/s
17:53 – winds are now 090 3m/s
17:58 – the aircraft descends into Coulter Field
18:02 – descending into Coulter Field
Camera # N/A
Impressions/Comments:
The cloud field today was uniform with a few isolated thunderstorms that were organized along
our flight track on I10. CCN counts were above 4000/cc along the I10 corridor, but the
occasional shower on our flight leg may have confounded these measurements. Winds were light
and variable during the whole flight period (see wind conditions at IAH above). Several brush
fires along the Conroe-Desata leg also may have increased the CCN counts occasionally. Air
traffic was not collaborating and the crew decided to cut the flight short in view of the light and
variable winds.
Instrumentation comments:
None