Mission Plan :

A genesis mission around what was to become Tropical Storm Danny east of the Bahamas. A zigzag pattern was to be executed to sample the storm and environment with dropwindsondes in all quadrants.

Mission Summary :

The mission was fully successful. The zigzag pattern was modified after takeoff to accommodate the changing structure of the system. Despite the lack of a center, three radar analyses were completed and sent from the plane. Twelve dropwindsondes were successfully sent as well. There were minor issues with the radar going down periodically. A reboot of the HAPS caused one sonde to be incomplete. The sonde was sent off the aircraft, but was corrected and resent. A merged radar analysis (Fig. 1) shows that convection was mainly seen to the east of the center, located at the northwestern point in the figure. The system was highly sheared at the time and was able to produce vigorous convection east of the center that showed reflectivity up to 16 km (not shown).

Figure 2. Merged radar wind analyses at 2.5, 3.5, 7.0, and 10.5 km altitude.

Merged wind analyses (Fig. 2) show southerly flow throughout at low levels with strongest winds well east of the center. Multiple weak cyclonic centers are visible at midlevels (3.5 - 7.0 km). The flow at upper levels becomes strong and easterly, exemplifying the shear over the system. However, dropwindsondes showed a rather coherent larger circulation in this region up to 3.0 km. (Fig. 3). Because of the lack of reflectors at the dropwindsonde location, this feature did not appear in the radar analyses.

Figure 3. Dropwinsonde data at the surface and 950 hPa.

Problems :