Mission Plan :

An Environmental Modeling Center-tasked Tail Doppler Radar (TDR) Mission into Tropical Storm Erika, which wcontinued moving westward toward the Leeward Islands. The plan was for a rotatedfigure-4 pattern (90 nmi legs) with four passes through the center of Erika with a final pass toward the return to Barbados (Fig. 1).

Mission Summary :

At the beginning of the mission, Erika was located about 395 km east of Antigua in the Leeward Islands and moving westward at 28 km h1 . The maximum sustained wind speed remained 75 km h1 , making it a weak tropical storm, and the minimum central pressure was estimated to be 1005 hPa. Convection had been decreasing near the core, with most convection off to the south suggesting moderate to strong wind shear.

The mission was conducted at 5000 ft altitude, lower than other missions, due to fix requirements from the National Hurricane Center. Even so, fixing a center was difficult during the mission, and, during three passes, the aircraft had to complete u-turns to find the center. The final pass was conducted at 10,000 feet altitude so that the Air Force Reconnaissance aircraft could fix the storm at 5000 ft at that time. None of the dropwindsondes released during the mission found tropical-storm-force winds at the surface. Easterly winds during the final pass, especially north of the center, were much stronger than those lower down, suggesting the impact of a jet containing dry air from the Sahara.

Figure 2: Reflectivity from the lower-fuselage radar at the times closest to the five center fixes.

During the mission, most of the moderate convection was located to the southeast of the fixed center (Fig. 2). The intensity and coverage of the convection was decreasing between the first and third pass, and increasing through the remainder of the flight. During the final pass, strong convection developed near the center, and was the strongest seen during all the flights this crew experienced in Erika. Radar data coverage (Fig. 3) was much improved over previous flight. A distinct tilt in the location of the center of Erika was seen in the radar analyses.

Figure 3: Doppler radar/dropwindsonde storm-relative composite of Tropical Storm Erika valid 2021 UTC 26 August at three levels showing the tilt of the center with altitude.

Sim Aberson
Sept. 3, 2015

Flight track

Temperature and Moisture

Wind and Atlitude

Lead Scientist's log | Radar Scientist's log | Dropsonde Scientist's log
Flight Director's log | 1 second data | Flight Director's manifest | NetCDF data | serial data

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