While the relatively quiet 2013 Atlantic hurricane season produced the fewest hurricanes on record since 1982, ranking it the sixth least-active season since 1950, this didn’t stop the Hurricane Research Division (HRD) of the Atlantic Oceanographic and Meteorological Laboratory (AOML) from having a successfully active season of data collection.
Flying aboard NOAA’s hurricane hunter aircraft, HRD scientists conducted missions into Tropical Storms Gabrielle and Karen, as well as Hurricane Ingrid, to gather data for research and assimilation into numerical models.
"This is the first data set collected within the hurricane to be used in the operational models."
As part of HRD’s annual Hurricane Field Program, the collected data supported the Intensity Forecasting Experiment (IFEX). A goal of IFEX is increasing understanding of the physical processes and other factors that enable tropical cyclones to change intensity, as well as improve tropical cyclone intensity forecasts.
In their efforts to gather data for research, HRD scientists released 136 airborne expendable bathythermographs and 367 dropwindsondes from NOAA’s P3 and Gulfstream-IV (GIV) aircraft. These instruments enabled them to obtain information about important features in the atmosphere and ocean. The G-IV jet gathered data during nine flights and the two P3 aircraft conducted 17 missions, for a total of 150 flight hours spent sampling these three tropical systems. Many of the flights were coordinated with NASA’s Hurricane Severe Storm Sentinel missions, which featured two high-altitude, unmanned, Global Hawk aircraft.
NASA Hurricane Aircraft
NASA's Global Hawk departs for its mission out of NASA’s Wallops Flight Facility near Chincoteague, Va. Credit: NASA
Additional to collecting data for IFEX, the P3’s tail Doppler radar data transmitted directly to NOAA Central Operations and successfully assimilated into the operational Hurricane Weather and Research Forecast (HWRF) model.
“This is the first data set collected within the hurricane to be used in the operational models,” says Frank Marks, the Director of the Hurricane Research Division. “It provided a dramatic improvement in the intensity forecast skill for the cases when it is available.”
The tail Doppler radar data provided vital information about the direction and strength of the winds found in Gabrielle, Ingrid, and Karen.
“This combined dataset allows us to better understand processes contributing to short-term intensity change,” explains HRD scientist Paul Reasor.
In addition, researchers developing data assimilation strategies for the HWRF model may use the G-IV radar data to explore the advantages of having wind observations at higher frequency than currently available with the P-3s alone.
NOAA Hurricane Aircraft
NOAA's G-IV jet now carries an operational Tail Doppler Radar that collect storm data for real-time modeling as well as research. Credit: NOAA
A new basin-wide version of the HWRF model developed at HRD was run in real-time during the season, allowing the concurrent forecasting of multiple storms for the first time. Additionally, HRD provided near-real-time runs of a research version of HWRF initialized with the Hurricane Ensemble Data Assimilation System (HEDAS), a testbed for improving the assimilation of data into the operational HWRF model.
Thanks to HEDAS, the models now incorporate high-resolution cloud-motion vectors, as well as other satellite retrievals. The model forecasts showed integration of these data with a sophisticated data assimilation system could provide better forecasts of track and intensity than the current operational system. HRD’s HWind group successfully made 33 surface-wind analyses for six storms that formed in the Atlantic basin this year.
"These accomplishments would not have been possible without the contributions of NOAA's Hurricane Forecast Improvement Project and the NOAA Aircraft Operations Center," Marks reminds us. “We are thankful for the successes and major milestones achieved during the 2013 Atlantic season, all without having a single hurricane make landfall in the U.S. and with only minimal loss of life and property due to tropical systems.”