CIFEX Experiment # 15
April 20, 2004.
Flight Scientist: Greg Roberts
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Flight #21: Take off about 6:05 am. Landed 9:44 am
Flight#22: Take-off: 12:06 Land: 15:58
20 April 2004
CIFEX flight #21
Objective: Intercept pollution layer and find stratocumulus cloud systems. We observed thick pollution layer between cloud systems and stayed in this layer for ca. 40 minutes. . Flight track northwest then north Times are local time (GMT = Local Time + 7)
Take-off: 6:05 Land: 9:44
After take-off, we flew through mixed clouds along coast with bases at 2400' and a higher stratus layer that extended from 4600' to 6000'. FSSP and 1DC concentrations were around 150 /cc and 30 /L, respectively. Ice cylinders were seen on the 2DC.
Once above the cloud, the aerosol conditions were clean.
o CN - 200`/cc
o PCASP - 21 /cc
o CCN - 127 /cc
o SMPS - peaks with diameters near 200 nm.
We went through another precipitating cloud system during the ascent during which the aerosol inlet iced over. Clouds tops were at 8500'.
6:26 - base of aerosol layer at 10500' o PCASP - 100 incr to 200
6:29 - continued flying through the aerosol layer; at 12500' o CN - 650 o PCASP - to 300 o CCN - 400 / SIO CCN stops working
Continue ascent through layer until cloud base at 14000'.
6:34 - added yaw on aircraft - check aerosol inlet performance 6:38 - Descend to 13000' and hold altitude.
6:43 - in aerosol layer o CN - 700 o PCASP - 250 o CCN - 400 and 0.8% S o SMPS - large, broad size distribution with peak at 100 nm.
6:55 - Observed non-precipitating cloud deck below with tops near 7000'
Consistent aerosol layer through leg.
7:14 - Clouds bases are becoming lower with cloud base at 12000' by the end of the leg.
7:16 - at cloud base, there was turbulence with ice on the 2DC.
7:24. - Begin descent to 8800'
7:27 - increase in PCASP concentrations to 300 /cc at 10500'
7:38 - begin return to Arcata
7:46 - ice forming on aerosol inlet at cloud top (ca. 7250')
7:53 - precipitation in the clouds - they may have developed during outbound leg
7:57 - dip below cloud
o CN - 328
o PCASP - 160
o CCN - 250 at 0.8% S
o SMPS - mostly large aerosols with peak at ca. 200 nm diameter
8:05 - SIO CCN not working - try restarting CCN
8:10 - begin ascent 8:12 - entered cloud base at 6000'
8:16 - hold altitude at 6800' for cloud sampling - ice forms on inlet
o FSSP - 30
o 1DC - 100
o 2DC - h2o drops mixed with ice
8:24 - descend out of cloud and begin race track returning on same leg at 1500'
8:26 - aerosol inlet melts 8:30 - hold altitude below clouds at 1500'
8:38- non - precipitating
o CN - 450
o PCASP - 150
o CCN - 168 / 350
o SMPS - bd / pk 100
8:49 - Begin vertical sounding Observed cloud base at 4000'; cloud top at 7500'
Parameters for check aerosol inlet - the 'aeriflow' values should be between 140 and 200 lpm. Ice if 'aeriflow' is less than 140 and 'aeritemp' is 6 to 10 degrees warmer than 'trf'
9:01 - much thinner space between cloud layers than earlier. Cloud base at 11.2k'.
9:09 - radar shows high clouds to 22k'
9:12 - aero layer.
o CN - 600
o PCASP - 300
9:30 - calibrate radar by flying in two circles at 45 degrees bank.
9:37 - below cloud near TH
o CN - 200
o PCASP - 120
o CCN - 58
o SMPS - large size distribution with peak diameter at 200 nm
CIFEX Flight #22
Objective: Intercept pollution layer and find stratocumulus cloud systems. The clouds were thick with tops often above 14000'. We observed aerosol layers up to 24000' (7.5 km).
Flight track west and south Times are local time (GMT = Local Time + 7)
Take-off: 12:06 Land: 15:58
After take-off, we held altitude at 1500' to prevent icing the aerosol inlet. The cloud systems were precipitation and the radar showed high clouds (above 12000'). Plane radar showed rain for the next 30 nm.
12:17 - ascend.to just below freezing level at 4000' to look for cloud top. Tops were above 12000'. 12:23 - SIO CCN not working
12:27 -.cloud tops at 14000' and slowly thinning
12:36 - begin quick ascent to 7500' to scout out situation above clouds.
12:38 - freezing level at 5800'
12:41 - use radar to determine that cloud tops were at 16-17k'
12:45 - begin ascent to above clouds and look for high aerosol layer.
o CN - 400
o PCASP - 100
o SMPS - most of the number concentration below < 100 nm
13:08 - find aerosol layer at 20200'
o CN - 2000
o PCASP - 300
13:25 - during flight south, we found another layer @ 19700.
13:43 - radar shows no precipitation below
13:45 - radar shutdown
13:49 - radar shows cloud tops at 11.5k'
13:51 - Spike.in CN from aethalometer restart
13:52 - hold altitude at 9700' to sample clouds; back in precip & ice so go back above clouds to sample aerosol layer.
14:03 - cloud top at 15.4k
14:08 - increase in CN at 20k'
14:12 - another aerosol layer at 21k'
o CN - 2000
o PCASP - 400
o SMPS - narrow with peak diameter at 50 nm
14:21 - aerosol layer at 22700'
14:27 - begin vertical profile from 24000' Aerosol layer from 23000' to 19000' was white in contrast to the layers earlier in the flight.
15:03 - cloud top at 11k' and cloud base at 7500'. As we continued to descend, the 1DC leaves a trail - perhaps evaporation of precipitation.
15:26 - end profile at 500'
Planned to do a fly-over at Trinidad Head, but cancelled due to no visibility.