Measurements of eddies in the ocean surface wind field by a mix of single and multiple-frequency HF radars on monterey bay california

To properly assess the impact of global climate change and plan for remediation, accurate regional climate models are necessary, functioning on 10 km size scales rather than the typical 100 km scales. Examples of 10 km size scale phenomena are coastal wind eddies at 10-40 km scales, studied over Monterey Bay,California by Archer,Ludwig et al. using shore and buoy anemometers and satellite images. Most frequent in the evening and early morning hours, these, typically cyclonic, eddies are often responsible for fog in the Santa Cruz California area. We have previously demonstrated the ability of multifrequency HF radar (4.8 to 21.8 MHz) to map the ocean wind field. Observations over a year time span indicate standard errors of prediction of 1.7 m/s for wind speed and 25deg for direction with biases of 0.1 m/s and 0.3deg respectively. Combining HF radar wind vector estimates with shore based anemometer data in the WOCSS surface wind field model allows formation of detailed (3 to 5 km resolution) images of wind eddies over Monterey Bay and observation of their creation and decay. We discuss requirements for wind field observations with HF radars and demonstrate how multiple radar sites can be used to produce HF radar wind field maps. We report observations of 10-20 km cyclonic eddies in the northern and eastern parts of Monterey Bay.