1950~2011年渤海地区海表风场的季节特征与多尺度变化分析

基于1950~2011年的NCEP/NCAR再分析资料,对渤海10 m风场的风速与风向变化进行多尺度分析。利用小波分析、交叉谱分析等方法对渤海海域的海表风速、风向的变化趋势以及周期进行研究。分析发现：渤海地区海表风的风向与风速除了存在显著的季节性变化特征外,在年际、年代际的变化尺度上也有明显的周期性。风向存在1 a、8.7 a、15.8 a的显著周期,风速存在1 a、6.3 a、15 a的显著周期。风向与风速在时间尺度分别为20 a、5.71 a、2.67 a时存在显著共振周期;共振周期受东亚季风、西太平副热带高压的年际、年代际变化的影响呈现出多尺度变化周期。

Multi-scale Variability of Surface Wind Direction and Speed on the Bohai Sea in 1950-2011

Multi-scale variability characteristics of ocean surface wind direction and speed from 1950 to 2011 are studied based on NCEP/NCAR reanalysis data. Sea surface wind field shows the seasonal characteristics. Results show that: in past 62 years, large area of wind direction in the Bohai Sea tend to be from northwest to northwest northand wind speed is the most in winter;wind direction tend to be from southeast to easterly winds and wind speed is the lest in summer; wind speed has started to decreased since 1970s and reduced significantly in winter. Wavelet analysis and cross-spectral analyzing are used to observe wind direction and speed on the Bohai Sea over the last 62 years. The characteristics of ocean surface wind direction and speed in the Bohai Sea show periodic oscillation at inter-annual and decadal scale. The main periods of wind direction are 1-year, 8.7-year, 15.8-year; whereas the main periods of wind speed are 1-year, 6.3-year, 15-year. The significant resonance periods between wind direction and speed are observed at the following temporal scales: 2.67-year, 5.71-year, 20-year. The resonance periods have relationship with variability of East-Asian Monsoon and Western Pacific Subtropical High.