Mission Summary
20070914I1 Aircraft 43RF
3-D Doppler Winds Operational Mission Summary
Tropical Storm Ingrid 2007

Scientific Crew (43RF)
LPS/Doppler/dropsonde Scientist Rob Rogers
Doppler/dropsonde ScientistBob Black

Flight Crew (43RF)
PilotsBarry Choy
Mark Nelson
Flight DirectorJackie Almeida
NavigatorPete Siegel
Flt. Eng.Dewie Floyd
Data TechTerry Lynch
Elec. TechJeff Smith
Damon Sans Souci

Mission Plan :

Fly a rotating Figure-4 pattern (Fig. 1) in support of 3-D Doppler winds experiment in Tropical Storm Ingrid. The leg lengths are 100 nm, with the initial point set up southwest of the storm and end up on the north side of the storm. The plan called for dropping sondes on the diagonal legs - at the end points and at points 1/3 and 2/3 of the distance between the end of the leg and the center of the storm. On the second Figure 4, along the cardinal directions, the aircraft would descend to 10,000 ft and get a fix for NHC on each pass.

Figure 1. Planned flight pattern (pink line) for 070914I. Black triangles denote locations of GPS drops.

Mission Summary :

The pattern was flown successfully. Takeoff was at 1949 UTC from Barbados. There were several instances where the aircraft had to deviate from the planned flight track to avoid convection. The storm was experiencing about 15 kt of westerly or northwesterly 850-200 hPa shear, according to the CIMSS analysis (Fig. 2), indicating that it was still in a marginal environment for intensification. On the first inbound leg, from the southwest, the SFMR winds

Figure 2. 850-200 hPa vertical shear (kt) from UW/CIMSS analysis valid 15 UTC 14 Sept. 2007.

were consistently about 10 kt higher than the flight-level winds. Once the possible center was passed, and the aircraft was on the northeast side of the storm, the wind relationship switched: the flight-level winds were about 10-15 kt higher than the SFMR winds. The center was very hard to find; in fact we were never able to find it from our altitude. The system was evidently tilted, with the surface low displaced to the north or northeast of the flight-level center (Figs. 3-4). The drop intended for the center showed easterly winds

Figure 3. GOES-12 visible satellite image of T.D. 8 valid 1915 UTC 14 September 2007.
Figure 4. GOES-12 infrared image of Tropical Storm Ingrid valid 1930 UTC 14 September 2007.

between flight level and 750 hPa, but between 800 hPa and the surface the winds shifted to westerly, supporting the idea that the surface center was displaced from the.flight-level center (i.e., the vortex was tilted). Convection was mostly south and southwest of the center, while there was some stratiform precipitation around the southeast side (Fig. 5). Peak winds that were encountered were 45 kt at flight level on the northeast side and 40 kt at the surface on the southwest side. Landing was at Barbados at 0402 UTC.

Figure 5. SSM/I F-15 85 GHz brightness temperature valid 2238 UTC 14 September overlain with GOES-12 infrared image valide 2215 UTC 14 September.

Doppler data was collected, in support of EMC’s goals. There were, however, occasional deviations due to the need to avoid intense convection and to find the center. This was a challenging case for automated Doppler processing, and for center-finding as well, due to the strong shear and the fact that it was a weak, disorganized system. It may make for an interesting case for the study of the response of a weak vortex to strong shear and possibly dry air.

Problems :

There were no major problems with the dropsondes or the SFMR. On one sonde on the northeast side, there were some problems with winds, but it is thought that these winds can be recovered in post-processing.

Robert Rogers

Mission Data:

1 second data | g'zipped NetCDF file

Flight track

Temperature and Moisture

Wind and Atlitude

Flight track detail

Page last updated May 8, 2008
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