Mission Summary
20190830H2 Aircraft 42RF
TDR into Dorian

Aircraft Crew (42RF)
Aircraft CommanderJustin Kibbey
Co-pilotJohn Rossi
Co-pilotAdam Abittol
Flight EngineerMike Sanchez
Flight EngineerTuffnel
NavigatorSam Urato
Flight DirectorIan Sears
Flight DirectorJack Parrish
System EngineerMac McAllister
Data TechnicianMike Mascaro
AVAPSTodd Richards
ObserverJames McFadden

Science crew (42RF)
LPSAndrew HazeltonHRD
DropsondeKathryn SellwoodHRD
RadarRob RogersHRD
ObserverZorana JelenakNESDIS
ObserverJoe SappNESDIS
ObserverTodd Reid
ObserverShaffer Shasta

Science crew (Ground)
RadarJohn GamacheHRD

Figure 1a. Flight plan for 20190830H2 mission for Dorian

Figure 1b. Actual Flight track for 20190830H2 mission for Dorian

Mission Plan :

This was an EMC-tasked Tail Doppler Radar (TDR) mission with a proposed butterfly pattern (Figure 1). The pattern was executed nearly perfectly.

Mission Summary :

Take off Landing
Linder_Lakeland, FL 20:43 UTC Linder_Lakeland, FL 03:47 UTC
Penetrations 3
Expendables 33 GPS all good
AXBT 2 good, 1 bad

Figure 2: GOES-16 infrared satellite image captured at 0020 UTC 31 August 2019

Figure 3: 850-200 hPa vertical shear analysis from UW-CIMSS
at 00 UTC 31 August 2019.
At the beginning of the flight, Dorian was a Category 3 hurricane with 100 knot (115 mph) winds, but was upgraded to a Category 4 hurricane with 115 knot (130 mph) winds based on the data collected on the flight. Figure 2 shows an Infrared satellite image of Dorian during the time of the flight. The TC was still relatively small, but by this time a clear eye had developed with deep convection surrounding the TC center, although the CDO was somewhat asymmetric, perhaps due to the presence of some fairly weak shear from the northwest (Figure 3). Despite the shear, the upper-level pattern was favorable for intensification, with two upper-level lows providing outflow channels for the TC (Figure 4).

Figure 4: Hurricane Analysis and Forecast System (HAFS) analysis of 850-200 hPa shear.
The two outflow channels aided by upper-level lows to the southwest and northeast of Dorian are highlighted.

Prepared by the Hurricane Research Division
Aug. 28, 2019 12:15 PM EDT
Aircraft: N42RF
Proposed takeoff: 30/2030Z
deg min deg min deg nm hr:min
1S26 2172 51 90/3001:33
2S24 5169 58 90/1202:19
3S26 2169 57 90/0602:42
4S24 5172 50 90/2403:28
5S24 0671 24 90/1803:51
6S27 0671 24 90/3604:37

Figure 5: 2-km TDR reflectivity/wind for the 20190830H2 mission (image from Paul Reasor).

Figure 6: Profile wind speed from the final inbound/outbound passes (S-N) of 20190830H2.

The radar data collected on the flight for assimilation into HWRF provided good coverage of the entire inner-core region of Dorian. Figure 5 shows the 2-km reflectivity and velocity data from the TDR, composited over the course of the flight. The storm had a small eye at this time (RMW 8 n mi), and despite the presence of several robust outer bands, there was no sign of an eyewall replacement cycle at this time. Profile analyses (e.g. Figure 6) showed that the strongest winds were around 0.5-km altitude.

One scientific module was carried out at the request of Nick Shay and Josh Wadler (UM RSMAS). This involved high-density dropsonde sampling of rainbands, to study the thermodynamic variability in and near convective features on both sides of the TC. This was done on the second pass across the TC, on the NE and SW sides, and involved dropping 3 mini sondes on either side of and in two rain bands (Figure 7), as well as performing a similar drop pattern in the RMW using regular sondes (Figure 7).

Figure 7: TDR 2-km reflectivity from the first two passes of 20190830H2, with the approximate
drop locations of regular sondes (red) and mini sondes (blue) on the second pass.

One final (late-added) objective of this mission was some high-altitude dropsondes (6 in total) along 29N to sample the strength of the subtropical ridge, which was critical to the steering of Dorian. This was requested by CARCAH and executed well by the flight crew.

Mission Evaluation / Problems :

Figure 8: SFMR wind speed (colors) and dropsonde locations
(brown squares) along the flight track during the 20190830H2 mission
(Image from Heather Holbach).

Figure 9: Flight level, SFMR, and dropsonde-adjusted wind speeds along the flight track for 20190830H2,
along with the extrapolated pressure and altitude (Image from Heather Holbach).

The mission was successful in gathering and delivering TDR data. 3 successful passes across the center were made, and a rainband structure module was also executed on the second. A high-altitude sonde sampling pattern was added in flight and executed successfully (Figure 8), altho ugh this prevented the gathering of ocean winds data. There were no major problems with the flight. 38 sondes were dropped and the data was good. 3 AXBTs were also dropped (two endpoints and one in the center) on the final pass across the storm, but only one of these was successful (the final endpoint). The data gathered throughout the flight showed a storm that had become quite strong, with pressure 950 hPa or lower and flight-level winds of 125 kt (Figure 9). This intensification continued as Dorian approached the Bahamas.

Mission Data :

Flight level wind along track

Flight level wind along track in storm

SFMR wind along flight track

SFMR wind along flight track in storm

Altitude, Pressure, Rain Rate, and Wind

LPS log | Radar log | Drop log
Flight Director's manifest | NetCDF data |

Page last updated Oct 29, 2019
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