ASCAT反演风场与华南及南海站点观测对比分析

COMPARATIVE ANALYSIS OF ASCAT INVERSION WINDS AND AWS OBSERVATIONS IN THE SOUTH CHINA SEA

关键词:  ASCAT反演风  南海  风场  浮标站  准确率  大气稳定度  高度订正

Key words:  ASCAT inversion wind  South China Sea  wind field  buoys  accuracy  atmospheric stability  altitude correction

摘要:

利用2014—2017年华南沿海及南海的浮标站、海岛站、石油平台站、沿海自动站等277个自动站风场数据，与ASCAT反演风场进行了对比分析。结果表明，当观测风速小于5 m/s(大于15 m/s)时，ASCAT反演风速的平均绝对误差在3 m/s左右(存在2级左右的高(低)估)；当风速介于5~10 m/s时，平均绝对误差在2 m/s左右(多数ASCAT有1~2级的高估)；介于10~15 m/s时，ASCAT反演结果相对最好，风速、风向准确率能够达到60%以上。ASCAT对风速的反演结果受陆地影响较大，与观测风速的相关系数从高到低可分为三类：(1) 浮标、平台站；(2) 西沙、南沙自动站；(3) 广东沿海自动站及海岛站、海南海岛站。ASCAT反演风场在风向的应用较风速更优，其中，东北风样本数最多，其次分别为西南风、东南风和西北风。浮标站、平台站、西沙自动站的风向反演质量相对较好；所有测站风向偏差主要由5 m/s以下的弱风贡献。单站多年月平均风速变化显示，ASCAT反演风速相对测站主要为正偏差，且秋冬季比春夏季偏差更大，这可能与大气稳定度有关。

Abstract:

The 10-m wind data between 2014 and 2017 from Advanced Scatterometer (ASCAT) and from 277 observations from buoys, island stations, oil platforms, and coastal automatic weather stations (AWSs) in south China and the South China Sea are compared. The results indicate that the mean absolute errors (MAEs) of scatterometers are about 3 m/s (prone to overestimations (underestimations) of 2 grades) when the wind speed is below 5 m/s (above 15 m/s), the MAEs are 2 m/s with overestimations of 1~2 grades in most cases when the wind speed is between 5 to 10 m/s, and the inversion matches with the observations best when the wind speed is between 10 and 15 m/s and the wind speed and direction inversion accuracy of over 60%. The inversion results of ASCAT on wind speed are greatly affected by land. As the wind speed correlation coefficients decline, the stations can be divided into three categories: (1) buoys and oil platforms, (2) Xisha and Nansha automatic stations, and (3) Guangdong coastal automatic stations and island stations, and Hainan island stations. The application of ASCAT inversion in wind direction is better than that in wind speed. Sample size of ASCAT is the largest in the northeast wind direction, followed by southwest, southeast, and northwest. Buoys, oil platforms and Xisha automatic stations have better wind direction correlation coefficients. The wind direction deviations of ASCAT among all stations are mainly due to low wind speed (below 5 m/s). The 4-year time series wind speed of buoys and oil platforms show that ASCAT inversion wind speed is mainly positive deviation compared with the data from weather stations, and the deviation is larger in autumn and winter than in spring and summer, which may be related to the atmospheric stability.