Coyote UAS Observations in Hurricane Maria (2017)

Scientists from NOAA’s Hurricane Research Division of the Atlantic Oceanic and Atmospheric Laboratory recently collected valuable and highly unique data from six (6) Coyote Uncrewed Aircraft Systems (UAS) deployed into Hurricane Maria. Using NOAA's P-3 reconnaissance crewed aircraft as a deployment vehicle, boundary layer observations of wind speed, wind direction, atmospheric pressure, temperature, moisture and sea surface temperature were recorded by the UAS. In all cases, High Definition OBServations (HDOBS) collected by the Coyote were transmitted to NOAA’s National Hurricane Center and made available to forecasters in near-real time.

A brief synopsis of the data collected from each mission is provided below.

Coyote flight 1 (Friday, September 22^nd 2017) Eyewall experiment -
Here, record endurance was attained for a Coyote UAS eyewall mission while controlled flight was maintained at altitudes as low as 100m. During this mission, the Coyote measured a maximum flight level wind speed of 55m/s. Similar to all missions that were conducted, NOAA's P3 hurricane hunter aircraft performed a complementary eye/eyewall pattern that coincided with the UAS’ estimated track.

Coyote flight 2 (Saturday, September 23^rd, 2017) Inflow experiment -
Coyote 2 attempted to spiral into the strongest winds of the storm. This mission was initiated WNW of the storm center. UAS stepped descents from ~1200 to 300m were conducted during this 33-minute flight. This experiment is expected to help model parameterizations within the very difficult to observe atmospheric boundary layer and surface layer environment (See related poster by Zhang et al.).

Coyote flight 3 (Saturday, September 23^rd, 2017) Eyewall experiment -
Similar to Coyote flight 1, approximately half of Maria's eyewall was traversed over a 32-minute period. Controlled flight was attained as low as 350m. This experiment was notable in that, to the best of our knowledge, a record was set for UAS-measured wind speed (64 m/s at 340m).

Coyote flight 4 (Saturday, September 23^rd, 2017) Eyewall experiment -
Coyote 4 covered a good portion of Maria's southern eyewall during its 32-minute flight. Separated by less than an hour from Coyote flight 3, these two consecutive eyewall missions, when combined, came close to completing an "eyewall orbit" of the powerful storm (which represents the first such pattern of its kind for any aircraft).

Coyote flights 5 and 6 (Sunday, September 24^th, 2017) UASonde gliders -
These flights were shorter in duration (7-8 minutes) due to engineering challenges that were encountered. Nevertheless, these deployments still retrieved useful data similar to what a dropsonde might collect as the UAS glided to the surface. Unlike a dropsonde however, these Coyotes remained aloft longer and were purposefully guided from a 10k deployment altitude through the transition region between the storm’s eye and the highly turbulent eyewall at very low altitudes. It also is worth noting that flight number 5 was recorded at 10hz for the entire mission (versus 2hz) which may enable the retrieval of valuable information related to the turbulent structure within the hurricane high wind surface layer (See related presentations by Bryan et al. and Dobosy et al.)

Analyses from these novel UAS missions will be presented.

Six additional studies that utilize Coyote data collected in Hurricane Maria will be presented by Aksoy, Dahl and Wiggins (OSE/OSSE) as well as Kalina, Ryan and Buban (numerical model evaluation).