Hurricane and Severe Storm Sentinel (HS3) Mission

HS3 2012-09-22 Flight Report: GLOBALHAWK AV-6

Flight Scientists:

Shift 1 (1600-0100 UT): Paul A. Newman, Ed Zipser

Shift 2 (0000-0900 UT): Michael Montgomery, Steve Guimond

Shift 3 (0800-1700 UT): Scott Braun, Pete Black, Gerry Heymsfield

Shift 4 (1600-0100 UT): Paul A. Newman, Ed Zipser

 

22 September 2012

1555 Engines started

Went through some problems bringing the Ku up. Unclear what was the problem

1742 Taxi

1750 Plane took off.

1830 Mission science requested a delayed release of the D03 sonde to give us a bit more spacing on the P31L system.

1920 After discussions with the pilots, we also adjusted D01 10 minutes earlier. D01-D02-D03 are now spaced 20 minutes apart.

 

LESSON LEARNED: All cloud plots need time stamps!

GOES visible image at about 1950Z (unknown without a time stamp). A clear circulation center for P31L can be seen in the image, with a trough axis oriented NNW from this center.

 

Position of AV-6 in the first leg of Nadine pattern at ~ 0200 UTC 9/22/2012.  Nadine has been stretched in the SW – NE direction by the mid-latitude flow.  It is hard to find the center of the system at this time.  In the last 30 minutes, there has been a cluster of lightning around 31 N 25 W associated with some moderate convection.  Nothing to worry about now, but we will keep an eye on this in the future.

 

We had considered a small northward displacement due to lightning within 25 nmi of the flight track, but the pilots were okay with continuing the current track.  Cloud tops were below threshold.  We are dropping an extra dropsonde between D23 and D24 as well as between D24 and D25 to sample the convective structure and potential outflow pattern.  Currently, convection is showing signs of development and we are monitoring cloud top temperatures for possible flight diversion.

 

 

Convection ceased developing as aircraft approached disturbed region.  Cloud top heights were 45,000 ft and below so no problems for aircraft.  There was lightning in the region, however, but the pilots didn’t have much concern with this.  Successfully dropped several sondes through the convection with two extra sondes (D23.5 and D24.5).

 

IR temps from NRL at 0824 UTC.  The above flight track is incorrect since the revised plan with east-west leg over estimated center did not load properly. 

 

Revised flight track entered at approximately 0800.  New horizontal leg will get over convective region.

 

IR temperatures at 0845.  Cloud tops are -65 to -70 C and CPL lidar tops were around 40kft.

 

Lightning at 0853.

 

 

Brightness temperature at 0945Z. Note that entire line of sondes were missed – AVAPS reset and working well at this time.

 

85 GHz brightness temperatures at 0600Z.

 

Visible image at 0915Z. Some overshooting tops on northeast side in 0845Z image.

 

85GHz temperatures at 0745Z.

 

IR temperatures at 0930Z.

 

SHIS approximately 11 micron IR temperatures.  Lowest temperatures were on 3^rd E-W line that appears to be on is on north side of  center.  Center moved moved southeast during the flight over storm.

 

Dropsonde intervals were modified on last flight leg. We started with 5 minute intervals by adding one sonde between original points, then we went to 4 minute intervals.  We added some extra sondes between D49 and D50, and added D51 further out in the northwest environment of Nadine.  No sondes will be released on the return flight over P31L.

 

Dropsondes during last leg.  First sonde on east side is dry above 800 mb.  Second sonde still on east side has 50-55kt wind between 500-700mb, and it is very moist up to 400 mb. Third sonde is on west side of center and has north-northeast winds at 50 kts near surface and 25 kts at 700 mb, saturated up to 850 mb. Fourth sonde at 1035Z has stronger winds (70 kt) at 925 mb but it cuts out below this level.

 

 

Sequence of GOES VIS images of Nadine during rapid sonde deployment (0915Z, 1045Z and 1215Z (couresy of NRL web site).

 

SSMI microwave image of Nadine at start of rapid sonde deployment

 

Infrared images near start of rapid sonde deployment, 0745Z left, 0915Z right.

 

Upper level water vapor images with NA872 flight track and sonde deployment locations, including rapid deployment leg.

 

 

TMI 0630Z (left) and SSMIS 0736 (right) with rapid sonde flight track

 

Lightning flashes seen on OLS night time VIS image at 0530 GMT. Lightning in band SE of center and near overshooting tourrets north of the center was supported by lightning network flash locations.

 

Drop name	Drop #	Drop Time (UT)	comment
D01	1	1957	Adjusted 10 early from planned position
D02	2	2015
D03	3	2042	Adjusted from original point to be 10 minutes later. Slightly delayed because of air traffic.
D04	4	0057
D05	5	0107	Some KU problems around this time.
D06	6	0117
D07	7	0129
D08	8	0139	Appears that KU problems have been fixed.NOT TRUE!
D09	9	0150
D10	10	0201
D11	11	0226	This sonde was delayed due to air traffic.  AVAPS did not get return data for this sonde.
D12	12	0241	Bit of a delay on sonde due to a turn.  AVAPS reports no telemetry information from sonde.  They are going into debug mode.
D13			Missed sonde due to AVAPS trouble shooting of telemetry issue.
D14			Missed sonde due to AVAPS trouble shooting of telemetry issue.
D15			Missed sonde due to AVAPS trouble shooting telemetry problem Above highlighted period was a disappointing string of sonde failures due to Ku band noise
D16	13	0326	Good sonde release, good returns.
D17	14	0337	Good sonde, good returns.
D18	15	0348	Good sonde
D19	16	0410	Good sonde
D20	17	0431	Good sonde
D21	18	0441	Good sonde
D22	19	0452	Good sonde
D23	20	0502	Good sonde
D23.5	21	0507	Good sonde.  Increased the sampling here to capture convection/outflow structure
D24	22	0514	Good sonde
D24.5	23	0519	Good sonde.  Increased the sampling here to capture convection/outflow structure
D25	24	0526	Good sonde
D26	25	0537	Good sonde
D27	26	0602	Delay due to aircraft turn.
D28			Skipped this sonde so we can place it in the convection on the west side of the circulation
D29	27	0635	[Sondes suspect this line] Sonde launched, but no data- begins another series of failed sondes (highlighted).
D30	28	0646	Sonde launched, but  no data, may need a reboot
D31			Reboot, skipped
D32	29	0706	Sonde  launched, but no data.  Did a reboot but this didn’t help.  Now appears that some data is coming in.
D33	30	0716	]Sonde launched but no data yet
D34	31	0726	Sonde launched and good data.
D34.5	32	0736	Sonde launched but no data yet
D35	33	0749	Problems with AVAPS – may recycle it
D36	34	0809	Recycled AVAPS and all on board systems just prior to D36, sonde dropout below 450 mb.
D37	35	0819	Recycling power on GH seemed to have cleared up noise issue. Good sonde
D38	36	0829	Good sonde
D39	37	0839
D40	38	0850	Good sonde
D41	39	0900	Good sonde
D42	40	0923	Good sonde
D43	41	0931	Good sonde
D44	42	1000	Good sonde
D44.5	43	1005	Good sonde
D45	44	1010	Good sonde
D45.5	45	1016	Good sonde
D46	46	1021	Good sonde
D46.5	47	1026	Good sonde
D47	48	1030	Good sonde
D47.5	49	1034	Good sonde
D48	50	1039	Good sonde
D48.5	51	1043	Good sonde
D49A	52	1047	Good sonde
D49B	53	1052	Good sonde
D49C	54	1056	Good sonde
D49D	55	1100	Good sonde
D49E	56	1105	Good sonde
D50	57	1111	Good sonde
D51	58	1131	Good sonde

Most interesting part of this flight was the E-W leg of rapid sonde deploments arranged at the last minute by changing the return flight route so that it passed through the center and then using remaining sondes at 4 min intervals to sample a section through the storm center. Two period s of sonde drop-outs due to Ku band noise interference limited the coverage of the storm environment, especially in the northeast quadrant and just south of the center. The noise issue seemed to be greatly reduced after power on the GH was recycled. When system came back up, remaining sondes were relatively noise free. This sondes on this east west leg showed detailed wind and thermodynamic structure of Nadine and fixed the center location, minimum pressure (990mb) and WL150 estimated surface maximum wind (52 kt). This represents the first true GH reconnaissance mission, and served as the basis for NHC upgrading Nadine back to ta tropical storm at 1100 am EDT, 1500 GMT. From Nadine advisory number 44 we have the following:

 

DEEP CONVECTION ASSOCIATED WITH POST-TROPICAL CYCLONE NADINE HAS

INCREASED SIGNIFICANTLY DURING THE PAST 12-18 HOURS. ALTHOUGH THE

THUNDERSTORM ACTIVITY NEAR THE CENTER HAS THINNED A BIT THIS

MORNING...THE LOW HAS MAINTAINED DEEP CONVECTION SINCE YESTERDAY

AFTERNOON. THERE HAS ALSO BEEN AN INCREASE IN ORGANIZATION OF THE

THUNDERSTORM ACTIVITY AS THE PRIMARY BAND NOW WRAPS ABOUT HALF WAY

AROUND THE CIRCULATION.

 

DROPSONDE DATA

FROM AN ONGOING NASA GLOBAL HAWK MISSION SUGGESTS THAT THE MAXIMUM

WINDS ARE NEAR 50 KT. A DROPWINDSONDE NEAR THE CENTER AROUND 1030

UTC MEASURED A PRESSURE OF 989.9 MB WITH STRONG WINDS...SO THE

ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MB.

 

The soundings from the rapid deployment leg showed very dry air on the east side of the storm with low level max winds estimated at about 40 kt accompanying a narrow moist slot. Profile peak wind seemed to be centered at 400- 500 mb on the east side of the storm and much lower, but stronger, winds of 70 kt at 925 mb (57 kt at 60 m altitude) on the west side of the storm. Soundings also showed deep moist charateristics west of the center, and downstream from the strong convection north of the center, in contrast to the east side. Winds decrease rapid with increasing height on the west side with only 25 kt at 700 mb above the low level wind max.