Mission Summary
20080722H1 Aircraft 42RF
Dolly Tail Doppler winds mission 2008

Scientific Crew (42RF)

Lead Scientist	Mike Black
Doppler/Dropsonde Scientist	Sylvie Lorsolo

Flight Crew (42RF)

Pilots	Barry Choy Al Girimonte
Flight Director	Barry Damiano
Navigators	Tom Gallagher Ryan Kidder
Flt. Eng.	Greg Bast Steve Wade
Elec. Tech	Bill Olney Joe Bosko

Mission Plan :

This was to be the 5th flight in a series of flights into Tropical Storm Dolly (2 each from N42 and N43 previously), which was strengthening in the western Gulf of Mexico as it headed NW toward the southern Texas coast. The mission objectives were a combination of reconnaissance fix responsibility at 1200 UTC, Doppler wind analyses and transmission for NCEP and HRD, overflight of AXBT locations (with sonde drops) from the previous N43 and N42 missions, and an array of GPS dropsondes to supplement the Doppler wind observations. The mission would be primarily conducted at 12,000 ft but a final W-E pass through the center at 5 kft was planned to facilitate better data collection for the NESDIS engineers onboard. A butterfly (rotating figure 4) pattern was planned with 3 center crossings.

Mission Summary :

The takeoff was on time at 0851 UTC and N42 headed southwest to an IP 105 nmi NE of DollyÕs center, which was reached at 1105 UTC. The leg inbound was from the NE to SW to the center and was aligned along an array of AXBT locations that N43 dropped on the flight earlier. We released 5 AXBT and dropsonde locations along this leg, including one in the center (eye) which measured a surface pressure of 993 mb. The SST measurements were still about 28.5° C, about the same as the observations made 12 hours earlier. The center, at 23.7°N, 94.0°W, was reached at 1128 UTC and the plane continued to the SW, releasing 3 more sondes at the RMW and mid- and end point of the outbound leg. The plane turned east at 1154 UTC (SW point) for a location 105 nmi SE of the eye which occurred at 1224 UTC where a sonde-AXBT combination were released. Our second pass was from the SE to NW, started at 1225, the center was at 1250, and the NW endpoint was at 1312 UTC. Six sondes (RMW, mid- and end point), and 3 AXBTS (NW portion) were released along this pass through the center (1250 UTC). N42 headed south from 105 nmi NW of Dolly's center and descended to 5 kft to a point 105 nmi west of the eye, reached at 1329 UTC. On our last pass from W-E, 5 sondes and 4 AXBTS were released. The sondes were at the western RMW, eye, eastern RMW, mid point, and endpoint of the eastern outbound leg. The AXBTS we dropped at the sonde location of the eastbound outward leg. A dropsonde in the eye measured 991 mb a the surface at, 2 mb lower than 2 hours earlier. After reaching our eastern most point at 1410, the aircraft climbed up to ferry altitude and headed back to base and landed back at MacDilll at about 1730 UTC.

Figure 1 shows the flight track and precipitation pattern from the LF radar on a 480 x 480 km domain. Dolly was now a strong tropical storm with a radar eye clearly visible. Flight-level, SFMR, and dropsonde wind measurements all indicated that the maximum surface winds were close to 60 kt, just below hurricane strength. There were no meteorological surprises on this flight as Dolly was a slowly- evolving and strengthening storm during the time of our flight. We suspected that Dolly would quickly gain hurricane status, which it did. We were able to successfully complete 3 Doppler radar analyses during the flight and transmit the products to computers on the ground.

Figure 1. Track of N42 overlaid on LF imagery. Times in UTC for the leg endpoints and center crossings are denoted along the track.

Figure 2 shows the flight-track with SFMR wind barbs (kt) along the track and locations of the 11 of the 12 AXBTs and 18 of the 19 dropsondes that were released (the last one is just to the east of the point labeled 1409). Center crossing were at 1128, 1250, and 1342 UTC. Dropsonde winds well above the surface were >65 kt but the SFMR and sondes showed 60 kt at the surface.

Figure 2. N42 flight track showing SFMR surface winds, AXBT (BT), GPS dropsonde (Drop) locations, and times of these drops along the track.

Problems :

The radar, flight-level, SFMR, and dropsonde systems all worked well on this flight. All 18 of the dropsondes were good as were the 12 AXBTS. All three of the real-time Doppler analysis looked good and were transmitted. NESDIS reported that their instrument functioned well. Overall, a very successful mission.

Michael Black
08/27/08

Mission Data :

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