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Mission Summary
990827I Aircraft N43RF

Hurricane Dennis XCDX/ Modified Air-Sea Interaction Experiment

Scientific Crew (43RF)
Lead ScientistP. Black
AXBT ScientistP. Black
Radar scientistJ. Gamache
GPS DropsondeM. Black
HRD WorkstationP. Dodge

Mission Briefing:

This mission was designed to monitor the structure of a slow-moving, slowly developing hurricane and to monitor the ocean structure underneath and ahead of the storm.

Mission Synopsis<

The flight departed Bermuda International at 1730 UTC, August 27 and landed at Miami International/ Signature Aviation at 0230 UTC, August 28, a duration of 9 hours. Flight altitudes in Dennis were 14,000 ft. A butterfly XCDX pattern was flown and 4 penetrations were made (Fig. 1).

A well-defined eye was encountered with strongest convection in the north and west quadrants of the eyewall and weakest on the south and east. During the second half of the flight, convection became very active in bands in the southeast quadrant and lightning was frequent.

A total of 8 AXBTs were deployed, all CAD-launched. AXBTs were launched with GPS sondes at the 75 nmi radius east, northeast, north and northwest of the center, as well as in the eyewall along each leg. Clean signals were observed to 350 m on all AXBTs. 34 GPS sondes were launched and 26 sondes were transmitted (Table 1).

Efforts were made to transmit SFMR surface winds, but one frequency was bad and error checking routines designed to eliminate erroneous frequencies was not operating properly, nor was the error checking routines to flag high over-land brightness temperatures.

Problems:

Except for the SFMR frequency problem all aircraft systems performed flawlessly. Once again, ATC, New York required us the shift the pattern 1 degree south on the inbound leg to avoid an unannounced restricted area.

Peter Black


 

Table 1
Splash locations of sondes transmitted during the 19990827I Dennis mission.

#

Sonde ID

Time

(UTC)

Lat

(°N)

Lon (°W)

Comment

1

984715200

27:18:18:00

31.300

-67.230

MBL WND 11509=

2

991435072

27:19:04:00

28.840

-69.770

MBL WND 12514=

3

991435008

27:19:39:00

28.230

-72.850

MBL WND 13022=

4

991435072

27:19:57:00

27.860

-74.390

MBL WND 11532=

5

985035200

27:20:04:00

27.490

-74.890

MBL WND 12039 LST WND

6

990415104

27:20:12:00

27.040

-75.310

MBL WND 11045=

7

991435008

27:20:30:00

25.920

-75.980

MBL WND 21015 EYE=

8

991435008

27:20:50:00

24.900

-77.010

MBL WND 31038=

9

991435008

27:21:06:00

24.130

-77.890

MBL WND 31025=

10

991435008

27:21:30:00

23.500

-75.960

MBL WND 24026=

11

991515008

27:21:50:00

24.970

-75.950

MBL WND 25040 LST WND

12

991435072

27:22:09:00

26.440

-76.150

MBL WND 08568 LST WND

13

991435072

27:22:20:00

27.240

-76.290

MBL WND 07551=

14

991435072

27:22:41:00

28.430

-76.480

MBL WND 09522 LST WND

15

991435072

27:23:00:00

27.780

-78.150

MBL WND 03522 SST 29

16

991435008

27:23:16:00

26.900

-77.280

MBL WND 04047=

17

991435136

27:23:53:00

25.910

-76.650

MBL WND 34053=

18

991435136

27:23:53:00

25.930

-76.670

MBL WND 34552 EYEWALL

19

991435136

28:00:05:00

26.210

-75.960

MBL WND 16051 LST WND

20

990845056

28:00:05:00

26.200

-75.950

MBL WND 16556 LST WND

21

991435136

28:00:24:00

25.220

-75.140

MBL WND 20545 LST WND

22

991037120

28:00:11:00

25.850

-75.950

MBL WND 20574 LST WND

23

990845184

28:00:38:00

25.100

-74.160

MBL WND 16539=

24

991515072

28:00:53:00

26.280

-73.820

MBL WND 13542=

25

991037120

28:01:07:00

26.510

-74.890

MBL WND 13054 RAINBAND

26

991515136

28:01:20:00

26.400

-75.930

MBL WND 13572 EYEWALL

Here MBL = mean boundary layer wind (fffdd; fff = wind direction in deg and dd = wind speed in kt),
and LST WND = height of last wind (meters).


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