上海沿岸海域灾害性大风特征研究与预报检验

Characteristics study and forecast validation of the gale along the coast of Shanghai

选取2011-2017年上海沿岸海域5个浮标站点的风场和海浪数据,分析了大风过程的时间和空间特征;对海浪成长过程进行风向分类,运用滑动相关分析统计了8个风向的海浪滞后时间;计算了大风起风时间的预报提前和滞后量,进行了风速风向的误差和准确率检验。结果表明:越往东部海域,大风时数越多,长江口区东部风速较大;大风极值主要出现在8月份台风过程,出现时段都为傍晚到半夜,大浪极值浪向以东北到东南向为主;秋冬季大风时数多,5-6月大风时数最少;大风风向以西北到东北风为主;海浪成长过程风向分布是东南-西北走向,海浪对风的响应滞后时间平均为3~4 h;大风起风时间预报较实况略有滞后,风速预报的准确率总体在70%以上,预报值较实况值偏小,口外浮标偏小最为明显,偏强率都为0;风向预报准确率低,误差大。

The special and temporal characteristics of gale along the coast of Shanghai is studies in this paper using the wind and wave data of 5 buoy stations from 2011 to 2017.The wave growing process is classified by the wind directions,and the lag time of wave in eight wind directions are calculated using sliding correlation analysis.The lead and lag of the forecast gale start time is calculated,and the error and accuracy of wind speed and direction is verified.The results show that the wind duration tends to increase with the distance to the east and the wind speed in the eastern Yangtze river is relatively larger.The strongest gale mainly occurs during the typhoon process in August from late afternoon to midnight.The direction of maximum wave is mainly between northeast and southeast.The gale duration is longest in winter and shortest in May and June,and the gale direction is mainly between northwest and northeast.During the growing process of waves,the wind direction distribution is in a southeast to northwest direction.The lag time of wave responses to wind is 3-4 hours on average.The forecast onset time of gale is slightly behind the actual situation,and the accuracy of forecast wind speed is generally above 0.7.The value of forecast wind speed is slightly smaller especially for the Kouwai bouy.The accuracy of forecast wind direction low with large errors.