Assimilation of scatterometer-derived winds into real-time tropical cyclone wind analyses

The Hurricane Research Division (HRD) of the NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) provides as guidance to hurricane forecasters near real-time sea-surface wind analyses of tropical cyclones. Sources of data for these analyses include Air Force and NOAA aircraft reconnaissance, buoy and ship observations, and surface observations from land stations in close proximity to storms. Until recently, no space-based remote wind measurements were included in the analyses, when wind vectors derived from low-level cloud motions in GOES visible imagery began to be utilized. It has been demonstrated that use of this wind information has a positive impact on the representation of the wind field in the data-sparse periphery of tropical cyclones. To this point spatial data coverage and time constraints have hindered inclusion of winds derived from other remote measurements into these analyses. The narrow swath width of the ERS-2 scatterometer ensures that measurements in the vicinity of individual storms are rare, and SSM/I does not provide vectors required as input to the analyses.

With the launch of the QuikSCAT satellite in June of 1999, a new source of wind data will be available to the HRD wind analysis system. AOML will be provided by NASA/JPL wind retrievals as soon as three hours after overflight, and with a swath width over twice that of the ERS-2 sensor will make the QuikSCAT data more useful. It is expected that this information will be provided in a timely enough manner and cover a large enough region to positively impact the analyses as have GOES cloud-drift winds.

The research that is the subject of this paper relates to the Operational Applications theme of the Conference on Satellite Meteorology and Oceanography.