HS3 Global Hawk Observes winds from tropical depression A95L in September 2013

This visualization shows wind flows from Tropical Depression A95L in the Gulf of Mexico between September 19 and 20 of 2013. The wind field was derived from data returned from dropsondes. The color of the winds represents altitude where ground-level winds are shown in white. Higher altitude winds, around 10km, are shown in orange and the highest altitude winds, around 15 km, are shown in red.

These dropsondes are probes that were dropped from the Global Hawk unmanned vehicle (part of the Hurricane and Severe Storm Sentinel project, HS3) as it flew in a lawnmower-like pattern over the storm. As the dropsonde probes fell through the atmosphere, atmospheric measurements including wind direction are recorded. Wind direction data from 88 different dropsondes were merged to create a single, derived flow field. The visualization shows particles moving through the flow field. The atmosphere is exaggerated 10 times to help differentiate various levels of the atmosphere. Only a thin slice of the atmosphere is shown at any given time, represented by a moving horizontal window.

Lower level winds show the cyclonic circulation associated with the tropical disturbance. But, just above those cyclonic winds, the storm is thwarted by wind shear, prohibiting further development into a tropical cyclone. NASA scientists use data from unmanned aircraft to better understanding why some storms develop into hurricanes and others do not.