Mission Summary
20120827H1 Aircraft 42RF
Tropical Storm Isaac TDR flight

Mission Plan :

NOAA42 will fly a tail Doppler radar (TDR) mission into Tropical Storm Isaac to gather tail Doppler data.
(http://www.aoml.noaa.gov/hrd/HFP2012/1_P3_TDR.pdf)
NOAA42 will take off from Jacksonville International at 0800 UTC and will recover at Jacksonville International by 1600 UTC the next day. The flight plan (see figure below) called for a rotating Figure 4 pattern with 105 nm legs at 10,000 ft with dropsondes at the end, middle, and RMW on each leg, and on the first and last penetration. Doppler analyses and quality control would be done on the aircraft and for the first time we would have someone on the ground (Mike Black) do dropsonde quality control.

Mission Summary :

As Tropical Storm Isaac passed into the southeastern Gulf of Mexico west of Florida (outlined in black line in top right of image) NOAA42 missions collected airborne Doppler radar data to use in initializing and evaluating model guidance (see flight track below). It was clear from the center drops that the central pressure was around 989 hPa and the SFMR suggested peak surface winds between 55 and 60 kts.

Included here you see images of the horizontal winds within the inner core of Tropical Storm Isaac sampled from the tail Doppler radar on the NOAA42 early on 27 August 2012. These images are at three altitudes, 1 km, 3 km, and 6 km, using a composite of winds from four legs oriented north-south, east-west, southwest-northeast, and northwest-southeast. Also plotted on the 1-km altitude analysis are the locations of dropsondes deployed (plotted using standard station symbols). Isaac's circulation is much more organized than in the previous mission, with a clear circulation center at all altitudes shown, but still very asymmetric with the stronger winds north and east of the circulation center. The circulation center is only slightly tilted from south to north with increasing altitude from 1-km altitude to 6-km, much less so than the precious mission. The observed tilt with increasing altitude suggests that the southerly shear Isaac is embedded in is much weaker than in the previous mission. Above 6 km the circulation center tilted 5-10 km to the north and almost vanished above 9-km altitude, suggesting the storm has a way to go is gaining strength.

Satellite imagery (below) depicted the cloud and precipitation structure during the missions. The top left image show the IR brightness temperatures which show a very asymmetric high cloud distribution with the coldest cloud tops (or the central dense overcast) to the west of the circulation center and very little cold cloud east of the center. There were cold clouds rotating around to the south of the center and over the state of Florida. The top right image shows the visible cloud filed with a few tall convective turrets in the rainbands north and east of the center along the track the aircraft entered the storm. Other than those turrets the vast majority of the high bright clouds are to the west and south of the center. The bottom two images are showing the condensed precipitation, where the lower left image is the 37 GHz color image that shows the emission signal from rain in the blue-green colors and the scattering emission signal from large ice in the pink colors. The lower right image depicts estimates of rain. Both images suggest that the heaviest rain was in the bands the north and west of the center, with strong ice scattering in convective turrets embedded in the cold cloud shield west of the center. The rain emission signal suggests bands are wrapping around the center, but there is no ice scattering on the east side.

26 GPS dropsondes were deployed, processed and transmitted during the mission. The figure below depicts the synoptic map of the surface observations from the dropsondes.

During our mission an AFRES C-130 deployed a string of 10 drifters (5 minMet and 5 ADOS) in across the track of Isaac to sample the upper ocean thermal and current structure as the storm crossed the array. The figure below depicts the location of the drifters relative to the sea-height anomaly plot. This NOAA42 missions was right over the center of the drifter string.

Mission Evaluation:

This was a very successful mission that met all objectives without any major issues. 5 radar analyses, sets of superobs and radial files were completed and transmitted to the ground. The dropsonde quality control from the ground worked wonderfully. M. Black was able to receive all the dropsondes, quality control them, notify us when they were completed, and we were able to grab them from the AOML ftp site and transmit them from NOAA42.

Problems :

We had a few radar system glitches when the power cycled, once when we were getting ready to take off and once during the mission. No significant amount of radar data was lost during the power glitches. The WSRA was not working during the flight and we eventually shut it off. No WSRA data was collected. There were some issues with the HDOB wind directions transmitted on our east-west leg suggesting that there may be a bug in AAMPS causing an 180° ambiguity in the wind direction between north and south.

Expendables used in mission:
GPS sondes : 26
AXBTs : 0
Sonobuoys: 0

Frank D. Marks
Sept. 18, 2012

Mission Data :