INDOEX C-130: FLIGHT 6, 27 February 1999 Objective: Indirect Forcing and Citation Comparison Obtain subcloud, in-cloud, above-cloud and remote-sensing observations for marine Scu over the Arabian Sea. Because cloud cover for the Scu fields is often below 20%, a strategy was adopted for taking advantage of the enhancements of cloud-cover fraction that appear to be due to waves passing through the boundary. Cloud amount appears to peak along a band typically 20 - 50 km in width and several 100 km in length. The band propogates at 30 kts--much faster than the surface winds. Pre-flight planning included projecting the location of the cloud band to be probed, based on early-morning satellite imagery and calling Male for updates of the imagery during the flight. In addition, legs of the flight were devoted to comparing radiometric measurements with AVHRR for the afternoon overpass of the NOAA-14 satellite and for comparing measurements made with instrumentation on the C-130 and the Dutch Citation. Planned takeoff of 04:00 GMT delayed due to aircraft blocking the C-130's access to the taxiway. Taxi began at 04:24UTC. UTC 04:28:30 Takeoff and climb to 1800ft 04:34 Level at 1800ft 04:34 Start descent for 100ft leg; flyby KCO 04:39 Start 10 minute leg at 100ft, west of KCO 04:43 Two photos of KCO flyby 04:49 5.35N, 73.35E. Climb to 15,000ft 04:51 Pass cloud top at 2100ft; pollution layer shallow at 5,000ft 05:01 Change heading aiming at 7.5N, 67.5E instead of original plan for 9N, 66E; ETA for clouds estimated to be 1 hr 45 min 05:05 Scattering less evident in uppler layer, but higher cold CN concentrations and lower hot CN concentrations 05:08 Some cirrus ahead 05:10 Top of scattering layer at 2.5 km on lidar and layer depth increasing? 05:14 Some small CN ~ 12 nm noticed at 05:05 flying at 16,000ft 05:24 CN increasing occasionally 05:30 Call Male; some cirrus south and SW of us; learn from forecasters that cloud front intersects 70E at 6.5N and 10N at 66.5E 05:35 SABL pointing up--no layers 05:48 LIDAR claims MBL with cloud top at 900m and cleaner than before; no clear layer at 2km as before 05:53 Some thin cirrus still ahead but should be OK; clouds appear to be less buried in pollution than previously 06:00 Two photos to N over clouds at 7.46N, 69.08E; clouds increasing below, probably near SE end of clouds to be probed; cloud cover on MCR appears to be about 10% 06:08:10 Clouds look good below; Coakley picture 7.48N, 68.5E 06:17 Turn to NE to reach center of cloud deck, 7.49N, 67.82E; cloud cover on MCR appears to be about 40% 06:27 Turn to 310 heading 06:28 Start 30 min run to NW at 310 true 06:32 Take photos to N--digital #46, #47 to N; MCR image appears to be delayed by about 1 min 06:45 Change heading to 280 to hit clouds (8.88N, 67.083E); no cirrus 06:53 Looks like MCR channel 1 saturating over clouds 06:58 End run and descend to 100ft at 1,000 fpm 07:00 LIDAR reports no variation looking down for past 30 min (?) 07:05 Hit pollution at 8,000ft; stronger layer at 6,000ft 07:09 Cloud top at 4,300ft; some drizzle in CVI 07:10 In cloud; bsp lower in cloud 07:15 Cloud base at 1,700ft 07:18 Touch 100ft and climb back to 500ft 07:21 Start 5 min circle at 500ft 07:26 Climb to 3,000ft 07:29 8.91N, 66.25E. Start 30 min in cloud at 3,000ft 07:31 Call Male; cloud front intersects 10N at 65E and 70E at 5N; in one hour, front expected to intersect 10N, 64.5E and intersects 70E at 4.5N 07:31 Mass Spec. dead; Armin to let us know in 30 min whether he can fix it 07:32 Digital photos 51 and 52 in cloud run 08:00 Descend to 100ft; more pollution this end--SE end of run on other, NW end 08:06 Start 5 min circle 500ft 08:13 Climb to 10,000ft at 7.94N, 67.6E 08:19 Out of clouds at 4,100ft 08:20 Pollution falls off near 7,000ft but still trending down to 8,000ft; clean at 8,500ft 08:24 Haze layer to N above main layer 08:39 Decide to head west to catch up with cloud front 08:49 Continue at 10,000ft heading SE to follow clouds 08:54 Start 30 min leg at 10,000ft above cloud to SE; 7.47N, 66.57E 09:08 Turn west to stay in cloud 09:20 Data system down; circle at altitude; heading of 120 looks best for clouds 09:40 Data system back up; start descent to 100ft 09:48 Cloud top at 3100ft 09:50 Cloud base at 1700-1800ft; visibility poor; can't see distinct cloud base 09:51 Start 8 min run at 300ft below cloud base 09:59 End 8 min run and climb for in cloud run at 2,500ft 10:03 Call Male; suggest rendevous with Citation at 5N, 72.5E at 11:50 UTC 10:08 Climb to 3300ft for 8 min above cloud run 10:22 Climb to 15,000ft to set up for satellite overpass; scattering in this area much less than in others--about 0.5 previous levels 10:34 Begin satellite overpass at 14,000ft on 167 true heading; flying under cirrus 10:41 5.3N, 66.2E. Cirrus ahead 10:46 End satellite overpass; climb to 21,000ft and head to 5N, 72.5E 11:03 Begin MCR manuever with sun behind tail; scene is broken Scu 11:08 Start second leg of MCR manuever with sun off wing 11:11 Complete MCR manuever and head to rendevous at 19,000ft and 11:50 UTC 11:43 Cirrus above 11:48 Humidity jump from 25 to 60%; cirrus above; some towering Cu in area; increase in CN as we head toward rendevous 11:55 5N, 73.30E 11:59 Start comparison at 19,000ft on 200 heading 12:07 Take pictures on leg 12:10 End 19,000ft leg and descend to 14,000ft 12:12 Deep convective clouds and layers ahead 12:13 Start run for 10 min at 14,000ft 12:21 Photo of Cu ahead--Dateback always in LST 17:21 12:24 Left turn and descend to 5,000ft near big Cu; reverse track to 020 heading moving away from big Cu but over small convective Cu 12:27 Start seeing haze layer at 2,500ft m(?) 12:30 Start leg at 5,000ft 12:41 Descend to 500ft; very small Cu at 450 m(?) 12:52 Scatter shows dramatic change 12:54 End run and climb to 3,500ft for return to Hulule 13:20 Land; laarge variation in aerosol at 3,500ft on approach Status Report: Cindy CVI Worked well; good characerization; need above and below coincident(?) Armin Mass spectrometer problem may be solved with new power supply Sarah Equipment worked well; pgm problems; would like day on the ground Jim Equipment worked well; similar to other days; Good CCN on CVI Mark TOAD problem; OPC volatile Anthony Most instruments OK; fraction down looking noisy; swap instrument tomorrow Tom MS worked fine; going to position mode for Citation Olga System OK Lidar Ran well AIMR Ran well MCR Ran well, but lacking IR channel ???? Data system OK Andy Probes worked well; 250X [260X??] uncertain