摘要
利用美国西海岸7个近岸浮标2012年全年和中国近岸8个气象浮标2012年1—6月的风场观测数据,检验了卫星散射计ASCAT近岸风场产品中的风速和风向在近岸海域的精度。检验结果表明:在美国西海岸近岸海域,ASCAT近岸风场产品中的风速与浮标的风速一致性高,但ASCAT近岸风场产品中风向的精度受离岸距离、风速和风向等因素的影响,在离岸近的海域ASCAT近岸风场产品与浮标观测风场的一致性较差。统计发现,将低风速(不超过3 m·s^(-1))剔除可明显提高ASCAT近岸风场产品在近岸海域的精度。另外,ASCAT近岸风场产品的风向精度在不同风向上存在差异,表现为从陆地吹向海洋风向精度较小,而从海洋吹向陆地风向精度较高。在中国近岸海域,受地形影响,渤海海域ASCAT近岸风场产品与气象浮标观测的风向差异大,在其他近岸海域的ASCAT近岸风场产品和气象浮标的观测风场的对比结果与美国西海岸风场的对比结果特征相似。
The new scatterometer advanced scatterometer （ASCAT）on board MetOp-A satellite provides surface wind speed and direction over global ocean.Providing accurate nearshore wind data from satellites is chal-lenging because satellite data are unavailable very close to shore due to the contaminating effect of the land.Besides,land-sea breezes and shore topography produce small space scale and time-scale wind varia-tions that can be smoothed by the satellite’s space averaging and aliased by the satellite’s twice-a-day sam-pling.The complexity of nearshore winds is one of the prime causes that the regions are so important.For example,over one-third of the total marine fish catch occurs within nearshore zone. The accuracy of ASCAT coastal wind product is determined through various comparisons with buoys. The nearshore buoys used in the comparisons locate in US West Coast and China Coast.As the time inter-val of US West Coast buoy wind is 10-minute interval and the spatial resolution of ASCAT wind product is 12.5 km,a scatterometer wind and a buoy wind measurement are considered to be collocated if the distance between the wind vector cell center and the buoy location is less than 12.5 km and if the acquisition time difference is less than 5 minutes in US West Coast.As the time interval of China Coast buoy wind is 1 hour,the acquisition time difference is less than 30 minutes in China Coast.The buoy winds at a given an-emometer height are converted to 10 m neutral winds in order to enable a good comparison with the 10 m scatteromter winds.The time ranges of wind data used for comparison from US West Coast buoys and China Coast buoys are the whole year of 2012 and the first half year of 2012 individually. It shows that the accuracy of the wind speed of ASCAT product is high and the accuracy of the wind direction of ASCAT product is influenced by several factors,such as the distance from coast,wind speed and wind direction.The overall wind speed correlation coefficient between buoy data and ASCAT product is 0.94,and wind speed correlation coefficients between each buoy and ASCAT product are all above 0.9. The overall wind direction correlation coefficient between buoy and ASCAT product is 0.71,and the wind direction correlation coefficient between the nearest buoy and ASCAT product is only 0.55.Processing the satellite data by discarding observations recorded in light winds （below 3 m·s-1 ）can improve the accura-cy of the ASCAT wind products by reducing the mean bias of wind direction from 21.89°to 11.83°,and the wind direction correlation coefficient increased from 0.71 to 0.84.In addition,the accuracy of the wind flow from land is low,while the accuracy of the wind flow from sea is higher.In most China nearshore re-gions,the applicability of ASCAT coastal wind product is good,but in Bohai Sea,the effect of topography on ASCAT coastal wind product is apparent.
出处
《应用气象学报》
CSCD
北大核心
2014年第4期445-453,共9页
Journal of Applied Meteorological Science
基金
公益性行业(气象)科研专项(GYHY201206001
GYHY201106006)
