近海岸风速衰减特征及形成机理分析

ANALYSIS OF THE CHARACTERISTICS AND FORMATION MECHANISM OF WIND SPEED ATTENUATION NEAR THE COAST

关键词:  内边界层厚度  风速衰减  离岸距离  摩擦速度  粗糙度

Key words:  thickness of inner boundary  wind speed attenuation  offshore distance  friction speed  roughness

摘要:

为更好理解沿海区域近地面风速衰减规律及其内在机制并获取适用于业务观测风速数据的分析方法，通过引入内边界层厚度的发展机理，推导获得风速随离岸距离变化的数学解析拟合式。结合浙江省温州市境内一沿海区域6个自动气象站2014—2019年逐时风速观测数据应用该拟合式分析了风速随离岸距离的关系，结果表明不管是逐时风速还是逐日最大风速，其平均值均与离岸距离有着良好的负相关，并发现其衰减系数与风速有着密切关系。向岸流及离岸流的风速衰减特性均可以结合该拟合式用线性及幂数律拟合来体现，但后者可以更好地解释风速随离岸距离变化特征，并在较大风速(3～10 m/s)向岸流的背景条件下，获得合理可信的分析结果，说明该方法可以适用于近海岸区域风速观测数据的应用研究。

Abstract:

In order to get more details on the characteristics and mechanism of wind speed attenuation in coastal areas and gain appropriate methods to analyze wind speed data from routine observation, the theory of inner boundary layer thickness is applied to the current research and an analytical expression of power-law fitting between wind speed and offshore distance is derived. Based on the hourly wind speed observational data from six automatic weather stations in the coastal area of Wenzhou, Zhejiang Province from 2014 to 2019, the relationship between wind speed and offshore distance is analyzed. The results show that both average wind speed and daily maximum wind speed have a good negative correlation with offshore distance. The attenuation characteristics of different wind can be expressed by linear and power law fitting, and the latter is better at explaining the variation characteristics of wind speed at different distance from the shore. Satisfying explanation under the background conditions of onshore flow and large wind speed is obtained, showing that this method can be applied to the analysis of routine observational data in coastal areas.