Although the 2015 hurricane season ending on Nov. 30th was by most measures a ‘quiet’ one, NOAA’s annual Hurricane Field Program, led by AOML‘s Hurricane Research Division entailed plenty of activity and produced several milestones. HRD scientists participated in 30 research, reconnaissance and surveillance flights, either on-board the NOAA aircraft or remotely from the ground. In addition, HRD scientists teamed up with NASA to remotely operate the Global Hawk drone in conducting high-altitude research of several hurricanes. In all, seven different tropical cyclones in the Atlantic as well as the eastern and central Pacific were investigated, including the record-setting Hurricane Patricia.
As a part of NOAA’s Sensing Hazards with Operational Unmanned Technology (SHOUT) project, data from the Global Hawk were ingested into an operational hurricane model for the first time. Also, two underwater gliders collected information on the sea’s reaction to the passing of Tropical Storm Erika. These data will enhance our understanding of the role of the upper atmosphere and ocean in hurricane dynamics and will lead to improved intensity forecast models.
Among the experiments carried out, a number used the NOAA aircraft’s tail Doppler radar to investigate the three-dimensional wind fields of these tropical systems. These data were transmitted in real-time to be incorporated into NOAA’s operational Hurricane Weather Research and Forecasting model. Lower fuselage radar images were transmitted for the first time to show the large-scale structure of the storms. In preparation for next year’s effort to assimilate the radar data from the NOAA G-IV jet into the operational computer models, extensive testing of that system was also carried out this season.
During other flights, a new instrument, the Doppler Wind Lidar (DWL), was used for the first time in a hurricane. This device returned wind measurements in regions where there was no rain. Traditional Doppler radar requires water droplets to provide targets for estimating the wind velocity, but the DWL can operate in clear-air, providing measurements over a greater area within the hurricane inner core.
Special emphasis was placed this year on gathering wind shear information in and around tropical systems. A strong El Niño year such this one often produces enhanced vertical wind shear over the western Atlantic, suppressing tropical storm formation. Examining research data from the Danny flights may offer insights on how wind shear affects hurricane development.