OSSE Evaluation of the Impact of Aircraft Observations on Hurricane Analyses and Forecasts

Kelly Ryan, NOAA Atlantic Oceanographic and Meteorological Laboratory

Abstract for Special Seminar on Friday, October 28, 2016 at 3 pm in Saguaro Hall, Room 101

Aircraft reconnaissance missions remain the only means of collecting direct measurements of marine atmospheric conditions affecting tropical cyclone (TC) formation and evolution. These airborne measurements are crucial in both the operational forecasting of TCs and the understanding of the mechanisms that drive intensification. NOAA/AOML’s Hurricane Research Division (HRD) annually conducts its Hurricane Field Program during which observations are collected via NOAA aircraft to improve the understanding and prediction of hurricanes.  Mission experiments suggest a variety of flight patterns and sampling strategies aimed towards their respective goals described by the Intensity Forecasting Experiment (IFEX; Rogers et al., BAMS, 2006, 2013), a collaborative effort among HRD, NHC, and EMC. Operationally tasked missions are required by NHC when a tropical cyclone threatens to make landfall in the U.S. or its territories and generally sample regions of highest uncertainty in GEFS in order to improve forecasting accuracy. Evaluating the potential impact of various trade-offs in track design and targeting method is valuable for determining the optimal air reconnaissance flight pattern for a prospective mission.

AOML’s HRD has developed a system for performing regional Observing System Simulation Experiments (OSSEs) to assess the potential impact of proposed observing systems on hurricane forecasts and analyses. This study focuses on investigating the potential impact of proposed aircraft reconnaissance observing system designs. Aircraft instrument and flight level retrievals were simulated from a regional WRF ARW Nature Run (Nolan et al., 2013) spanning 13 days, covering the life cycle of a rapidly intensifying Atlantic tropical cyclone. The aircraft trajectories of NOAA aircraft are simulated in a variety of ways and are evaluated to examine the potential impact of aircraft reconnaissance observations on hurricane track and intensity forecasts. Results from sensitivity studies provide insight into improvements for real-time hurricane targeting techniques.