浙江北部近海边界层风廓线特征分析

Characteristic Analysis of Near-Surface Boundary Layer Wind Profile over Northern Coastal Zhejiang Seas

利用2010年12月至2014年5月宁波近海凉帽山370m高塔气象梯度风观测和浙江北部沿海自动气象站测风资料,对浙江北部近海风速垂直廓线进行分析,结果发现:受地形影响,偏南、偏北风时塔基风速一般比上一层风速大。不同天气系统影响下近地边界层风廓线不同,南风型320m以下风速基本遵从对数律。热带气旋影响型和北风型时风廓线可分为3段,常通量层内基本满足对数律,该层向上一段高度热带气旋影响型风速变化不大,北风型反而减小,再往上风速又继续增大。北风型风廓线的这种3段结构表现比热带气旋影响型更为清楚,约80~109m风速出现相对极大值,200~250m间存在风速极小值。满足对数律的近地边界层内小风比大风具有更好的拟合优度。浙江北部沿海自动气象站测风资料不同风型统计分析与高塔风廓线表现基本一致。

Based on the meteorological observations from December 2010 to May 2014 of the 370 m observation tower on the Liangmaoshan Island of Ningbo and the automatic weather stations along the northern coastal Zhejiang province, an analysis is made of the wind profile characteristics in the near- surface boundary layer in different prevailing winds and different wind forces. Results show that wind speed at the tower base was stronger than that of the next upper layer in north or south wind because of topography. The wind profiles were different under different weather patterns, which basically meets the logarithm law at layers below 320 m when wind is from south, but when the tower was affected by TCs or the winds from north, the profile could be separated into 3 layers： within the constant flux layer, the winds meets basically the logarithm law; at the next layer above, there exists usually a layer with hardly changing velocity because of TCs, and there is slight decreasing in north winds; at the upper layers, winds increase. The three-layer structure is more obviously while north winds prevailing than TCs affecting, with the maximum velocity at about 80 to 109 m and the minimum at 200 to 250 m. Within the layers with the wind profile following the logarithm law, the fitting goodness of weak wind profiles is better than that of strong winds. Investigation on the profile of AWS observations indicates a consistent performance.