弱海平面气压梯度下大风成因分析

2013年4月29日大风天气过程，海平面气压梯度弱，预报有一定难度，若漏报将产生严重影响，甚至造成农业损失．因此，对这次弱气压梯度下大风成因进行总结与分析，对大风预报和农业防灾减灾有重要意义。分析结果表明，这是一次冷锋过后的偏北大风过程，但地面冷高压前沿气压梯度小，因此这次大风天气过程的主要原因不是海平面气压梯度，而是由变压风、冷平流、动量下传、前期显著回暖等引起，另外，T639、EC细网格和GFS数值预报模式的10m风场产品对这次过程的平均风向风力预报较好，江苏WRF模式的10m风场预报部分站点平均风力偏大，但对阵风的预报指示意义很好。检验结果表明，江苏WRF10m风场对阵风6级以上的大风有较好的预报能力。

Analysis on the Causes of a Gale with Weak Sea Level Pressure Gradient

The gale with weak sea level pressure gradient on April 29^#, 2013 was not easy to forecast. Missing prediction would have a serious influence, or even cause losses of agriculture. Therefore, analysis on the causes of the gale with weak sea level pressure gradient had an important significance for forecasting gale and agricultural disaster prevention and mitigation. It was found that the northern gale was caused by passing cold fi＇ont. The front of the surface cold high pressure gradient was weak, so the main reasons of the gale were not the sea level pressure gradient, but the isallobaric wind, the cold advection, the downward momentum transmission and the early significant temperature rising. The 10m wind products of T639, EC-thin and GFS numerical prediction models had good performances for the average wind. The 10m wind fields of Jiangsu WRF model were large for the average wind at part stations, but made a good call about the gust. The examination result showed that 10m wind products of Jiangsu WRF had better forecasting ability for the gust higher than force 6.