Tuesday, 24 January 2012: 2:00 PM
Wind Field Distribution within Hurricane Force Extratropical Cyclones Over North Pacific and Atlantic Using QuikSCAT Scatterometer Measurements
La Nouvelle A (New Orleans Convention Center )
Extratropical cyclones (ETCs) that reach hurricane force intensity are a significant threat to the safety of life at sea and a risk to cargo and vessels. ETCs vary on scale from less than 100 km in diameter up to 4,000 km in diameter and have an average life cycle of five days from genesis to death. Associated wind conditions can range from light (10-20 kts) to hurricane force (HF) (>63 kts). Knowledge of the wind structure, the frequency of occurrence and distribution of HF winds in ETCs has been greatly enhanced by data from the QuikSCAT scatterometer. QuikSCAT wind measurements have shown that HF winds in ETCs in the Northern Hemisphere are: much more frequent than thought; occur most frequently in the late fall through winter months; are short-lived (on average 24 hours or less); tend to occur in particular locations of the cyclone; and can cover tens of thousands of square miles. ETCs are frequent over the Northern Hemisphere oceans and at any given time during the fall through early spring as many as five to eleven observed cyclones, at varying stages of intensity can be present over North Pacific or Atlantic. Using the 10 year long QuiksCAT wind vector data records, we examine the climatological trends, characterize the size, the wind field structure, the frequency of occurrence and the distribution of HF winds within ETCs in the Northern Hemisphere. We also examine the difference in trends and characteristics of HF ETCs resulting from QuikSCAT and ASCAT scatterometer observations and the winds from the ECMWF and Cross-Calibrated Multi-Platform (CCMP) Ocean Surface Wind Components time series.