92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012: 2:45 PM
Assimilation of High-Resolution Satellite-Derived Inner-Core Observations for Hurricane Initialization
Room 340 and 341 (New Orleans Convention Center )
Fuqing Zhang, Pennsylvania State University, University Park, PA; and X. Ge, J. Knaff, Y. Weng, and J. Poterjoy

For the past few years, we have been developing an ARW-based ensemble data assimilation (EnKF) that utilizes the ground-based and airborne Doppler radar observations for high-resolution convection-permitting hurricane initialization and forecasting. The real-time and retrospective runs for all 62 applicable 2008-2010 airborne Doppler missions show 15-40% improvements for hurricane intensity forecast over the NHC official forecast for lead times of 24-96 hours (Zhang et al. 2011 GRL). The current study seeks to better initialize tropical cyclone vortices with high-resolution observations derived from satellites, especially when airborne or ground-based radar observations are unavailable. We will begin with assimilation of the Multi-platform Tropical Cyclone Surface Wind Analysis (MTCSWA), a global satellite-based tropical cyclone surface wind product retrieved from multiple satellite platforms using a variational data fitting method (Knaff et al., 2011) as well as the IR-based analog flight-level winds (i.e., IRWD, Mueller et al. 2006). The input data of MTCSWA includes the oceanic wind vectors (OWV) from the Advance Scatterometer (ASCT) on board the METOP-2A satellite, cloud drift feature track (CDFT) and water vapor (WV) winds from geostationary satellites, balanced flight-level winds estimated from the Advanced Microwave Sounding Unit (AMSU) data from NOAA 15, 16 and 18 (Bessho et al. 2006) satellites, and flight level analog winds created from infrared imagery and operational intensity and position estimates (IRWD). The IRWD is an important input as it provides flight-level inner-core winds, including realistic maximum winds and an estimate of the radius of maximum winds. The IRWD observations also extend out to 400 km radius of a tropical cyclone. The MTCSWA provides 10-m winds in polar coordinates with 4.5 km radial and 10 azimuthal resolutions, and can resolve the very strong winds within 200 km or so of the tropical cyclone center.

Our preliminary results assimilating the MTCSWA observations for all tropical cyclones initialized every 6 hours with best track wind speed greater than 33 m/s during the 2010 Atlantic hurricane season are very promising. Verified over more than 100 events, both the ARW forecasts of both hurricane track and intensity with assimilation of the satellite-derived wind are markedly better than the operational regional hurricane prediction models of GFDL and HWRF, as well as comparable or better than the NHC official forecast. Preliminary analysis also shows that assimilation of the high-resolution satellite-based wind observations may be just as effectiveness as assimilating airborne Doppler radar observations, at least in terms of the 1-5 days' track and intensity forecasts. The high temporal and global availability of the satellite-derived observations has the potential to extend our success to the vast majority of Atlantic and East Pacific cases and to other tropical cyclone basins that do not have airborne Doppler radar observations.

Supplementary URL: