Extended Abstract (136K)P2.11
Hurricane Force Extratropical Cyclones as Observed by the QuikSCAT Scatterometer
Joan Ulrich Von Ahn, STG, Inc. and NOAA/NWS/NCEP, Camp Springs, MD; and J. M. Sienkiewicz, J. Copridge, J. Min, and T. Crutch
Scatterometer derived winds from the QuikSCAT satellite have been used by NOAA/NWS Ocean Prediction Center forecasters in the warning and forecast process since the fall of 1999. The QuikSCAT retrievals are the first data set to consistently reveal winds 32 m/s or more within extratropical cyclones (hurricane force). Inferred winds of 47.5 m/s have been observed. This consistency has given forecasters confidence in identifying extreme extratropical cyclones.
This study examines the climatology of hurricane force extratropical cyclones over the North Pacific and North Atlantic Oceans. The periods of the study were October 2001 through April 2003. All of the extreme storms occurred in the months of October through April. Maximum frequency occurred in the North Pacific in November and December and in January for the North Atlantic. A minimum of occurrence was observed in the Pacific in the months of January.
Over the two years of this study, eighty-two cyclones were observed to reach hurricane force strength. Forty-five were observed in the Atlantic and thirty-seven in the Pacific. Geographic frequency plots reveal preferred tracks in both oceans. Maximum activity was observed over the western portions of each basin. The Pacific showed a minimum of activity between 175W and 165W degrees longitude. A minimum was observed near the European continent in the Atlantic. Storms maintained hurricane force intensity for an average of 18 to 20 hours.
The hurricane force winds were plotted in relation to each cyclone center. A composite of these plots was constructed. Hurricane force winds were most frequently observed in the south and southwest quadrants of the low center. The Atlantic storms showed a separate maximum to the north and northwest of the center. Many of these were orographically induced high winds along the Greenland Coast.
Poster Session 2, Atmospheric, Oceanic and Land Observations
Wednesday, 14 January 2004, 2:30 PM-4:00 PM, Hall AB
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