Thursday, 26 January 2012: 9:00 AM
Use of High-Resolution Spaceborne Measurements for Wind Power Climatology
Room 257 (New Orleans Convention Center )
Over the pass decade, there has been considerable development of the ability to make high-resolution (<1 km) wind speed measurements over the ocean, particularly in coastal areas. Spaceborne synthetic aperture radars (SARs) make high resolution radar cross section measurements which when used in conjunction with model wind direction estimates have been shown to achieve better than 2 m/s accuracy. NOAA is currently implementing a program to make these measurements operational. From 1996 to 2008, the Radarsat-1 satellite SAR acquired hundreds of thousands of images, at resolutions from 25 to 50. This data set represents an important long-term resource of wind climatology. Under the sponsorship of the State of Maryland, we used these 12-year long data to make an assessment of the potential for offshore wind power. In particular, we focused on the region 75.30°W to 74.75°W in longitude and 37.75°N to 39.00°N. Data were averaged into a spatial array filling this rectangle in 250 m samples. Data were uniformly spread across months, save for January, which was over-represented. We then normalized data so as to reduce the impact of January data to that of the other months. SAR wind speed retrievals are tuned to 10-m height above the surface for neutral atmospheric stability. Using a standard wind profile applicable to coastal areas, the wind speed measurements were converted to their equivalent at 80-m hub height. The applicable parameter for wind speed assessment is power flux density (power/unit area). Potential wind power flux density is proportional to wind speed to the third power. We found that at about a distance from shore of 4 km, potential wind power density reached the important threshold average of 300 Watts/m2. At 25 km from shore the average power density exceed 450 Watts/m2. In this presentation, we will describe the capabilities and limitations of SAR wind speed retrievals and how such data were processed to make wind power assessments. We will also discuss the implications for making these assessments over the entire coastal area of the US. The image below show the wind power flux density for wind power that was computed.