Mission Summary
20120822H1 Aircraft 42RF
Tropical Storm Isaac TDR flight

Aircraft Crew (42RF)
Aircraft CommanderHarris Halverson
Co-pilotCathy Martin
Co-pilotJustin Kibbey
NavigatorPeter Siegel
Flight EngineerJoe Klippel
Flight EngineerLonnie Kregelka
Flight DirectorPaul Flaherty
Flight DirectorJess Williams
Data TechnicianTerry Lynch
AVAPSJeff Newnam
Electronics TechnicianTodd Richards
Electronics TechnicianBobby Peek
Scientific Crew (42RF)
Lead ScientistRob Rogers (HRD)
Radar ScientistJohn Gamache(HRD)
Dropsonde ScientistTomislava Vukicevic(HRD)

Figure 1. Proposed track for 20120822H1

Mission Plan :

NOAA 42RF will fly an EMC-tasked Tail Doppler Radar (TDR) mission into TS Isaac, which is moving over the windward islands north of Barbados. This is the first P-3 mission into the system. Fly a rotating figure-4 (Fig. 1), with 105 nm leg length, with the initial point on the south side of the storm. Upon completion of the fourth pass, set up for a second west-east pass, and exit the storm on the east side. Drop sondes at turn points, mid points, RMW, and on first and last passes. Fly at 10,000 ft on the first pass over the islands, then descend to 8000 ft for the remainder of the mission to optimize scanning radar altimeter (SRA) measurements. No AXBT's will be dropped.

Mission Summary :

Take off Landing
Barbados20:16 UTC Barbados03:57 UTC


Figure 2. (a) GOES-East 1-km visible image valid 2045 UTC 22 August
(b) GOES-East infrared image valid 2045 UTC 22 August.

Isaac appears disorganized on satellite imagery, with peak winds from NHC at 40 kt. There are some areas of deep convection on the southwest and east sides of the center (Figs. 2-3), but the core does not appear to be organizing at this time. It does appear to be encountering some shear around the periphery and some dry air is evident on the north side (Fig. 4). There appear to be abundant scatterers near the center and south of the center, but limited coverage on the north side.


Figure 3. (a) TRMM 37GHz image valid 2119 UTC 22 August
(b) TRMM 85GHz image valid 2119 UTC 22 August.


Figure 4. (a) SSM/I Total precipitable water (shaded, mm) valid 0000 UTC 23 August
(b) CIMMS-derived 850-200hPa vertical shear magnitude (contour, kt) and streamline and infrared image valid 0000 UTC 23 August.

Takeoff was at 2016 UTC from Barbados. The pattern was flown generally as planned, but there were frequent modifications because of the difficulty in finding the center (Fig. 5). This modification was particularly evident on the final west-east pass, where the aircraft deviated to the south prior to reaching its center because of the suspicion that the center at flight-level was significantly displaced to the south. The SRA was not working so the aircraft climbed to 10,000 ft for most of the pattern.

Figure 5. Actual flight track for 20120822H1. Barbs (kt) shon for flight-level winds.

There were many challenges on this flight. The Doppler analyses are suspect, but we are not sure if that is related to the use of old quality-control parameters being used in the new radar data system (i.e., RVP-8), a lack of scatterers, a weak, disorganized system, or some combination of factors. The transmission scripts to EMC also had problems during the flight. Attempts were made to manually ftp the data. The dropsondes worked fine, but we had to manually transmit the tempdrop messages. The SRA did not work.




Figure 6. Dropsondes released during 20120822H1. Barbs show wind in knots.
(a) 700 hPa; (b) 850 hPa; (c) 925 hPa; (d)surface.

Adding to these challenges, as mentioned above, was that this was a very disorganized storm. Dropsondes clearly showed a cyclonic circulation, but it was not at all clear that it was a closed circulation, especially at 700 hPa (note these dropsondes are plotted earth-relative, not storm-relative). Some of the difficulty of seeing a closed circulation at 700 hPa may have been related to the presence of a strong easterly jet at that altitude, particularly north of the storm, as winds as strong as 30 kt were evident at the most northwestern point. Dewpoint depressions as large as 5-6 K were also evident at 700 hPa, especially on the west and southwest side of the storm. It is not known at this time whether this is consistent with the total precipitable water plot shown in Fig. 4a. While the winds are suspect, an examination of the Doppler-derived fields from 1-7 km altitude (Fig. 7) shows a closed circulation at 1 km altitude (as confirmed by coincident dropsondes) and primarily strong easterlies at higher altitudes. Easterly winds as strong as 20-25 m/s were seen on the north side of the storm at 7 km altitude. Even with this disorganization, there were some areas of deep convection and lightning, especially on the east side of the storm. It remains to be seen if the storm will become better organized.

The aircraft completed its mission and landed at Barbados at 0357 UTC.




Figure 7. Doppler-derived wind speed (shaded, m/s) and vectors (m/s) at
(a) 7 km; (b) 5 km; (c) 3 km; (d) 1 km. Dropsonde measurements at same level are also indicated.

Mission Evaluation:

The primary objectives of the mission were accomplished, though there were problems with the transmission of the radar analyses and tempdrop messages, which had to be manually transmitted.

Problems :

The primary problems with this flight were the suspect Doppler analyses, difficulty transmitting radar analyses and dropsonde tempdrop message, and the SRA not working. Despite these problems, data was collected that will be useful for future research.

Mission Data :

Flight Director log | LPS log | Radar log | Drop log

serical data | 1 sec data | NetCDF file | raw Fast data | SFMR data

Flight track

Temperature and Moisture

Wind and Atlitude

Page last updated February 20, 2013
Return to Mission page.