Extended Abstract (80K)15B.1
A comparison of sea level pressure analyses derived from QuikSCAT winds to manual surface analyses produced in the NOAA Ocean Prediction Center
Joan M. Von Ahn, STG, Inc. and NOAA/NESDIS, Camp Springs, MD; and J. M. Sienkiewicz and J. Patoux
The SeaWinds scatterometer onboard the NASA QuikSCAT satellite has provided Ocean Prediction Center (OPC) forecasters with Near-Real Time (NRT) ocean vector wind retrievals over large ocean areas since 1999. QuikSCAT wind retrievals have since become fully integrated into the OPC warning and analysis process. The impact of QuikSCAT winds on OPC operations has been extremely significant. QuikSCAT has given forecasters the ability to differentiate between all wind warning categories, in particular, between common STORM force winds and extreme HURRICANE FORCE conditions. In addition to warning decisions, QuikSCAT winds are routinely used to locate and position frontal features, lows and highs, and to determine the aerial extent of wind areas. Never before have forecasters' assessment of conditions over the vast open oceans been more accurate. Recent surveys have revealed that 10 percent of all wind warning decisions made by OPC forecasters and 30 percent of changes to the wind field are a direct result of QuikSCAT winds. Due to lack of surface pressure observations over the open oceans accurate representation of the Sea Level Pressure (SLP) field remains a problem. The central pressure of low pressure systems is often analyzed too high. Forecasters depend on the six-hour surface pressure forecasts from the latest National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) model as the primary guidance for their analyses. The Planetary Boundary Layer (PBL) Research Group of the Department of Atmospheric Sciences at the University of Washington has developed a planetary boundary layer model (UWPBL4.0) to calculate various PBL quantities. The inverse or pressure retrieval model subroutine estimates the surface pressure field using Level 2B Science Level winds from QuikSCAT. Using this model we have been able to generate dynamically consistent surface pressure fields for various North Atlantic and North Pacific extratropical cyclones. In most cases it was found that the central pressure of the storms was not analyzed to be deep enough by numerical analyses and forecast and manual analyses. This paper compares the QuikSCAT derived SLP fields with OPC manual and numerical analyses. Based on these results the OPC plans to make QuikSCAT ocean vector wind derived SLP fields available to forecasters in near real time. The use of this capability in OPC daily operations will be a valuable analysis tool for forecasters.
Session 15B, Data Assimilation III
Friday, 5 August 2005, 8:00 AM-10:00 AM, Ambassador Ballroom
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