夏季太湖局地气候效应的数值模拟研究

Numerical study on summer local climatic effect over Taihu lake

利用WRF模式,通过数值模拟试验研究了夏季太湖的局地气候效应,揭示了太湖对局地降水、温度等气象要素的影响,并探讨了内在的物理机制。结果表明:太湖主要在局地尺度上引起夏季地面气温降低和降水的减少,影响强度从湖区向周边地区逐渐减弱;太湖引起的夏季降水减少主要来源于对对流性降水的减弱作用;太湖对湖区及邻近区域夏季地面气温和降水的影响表现出明显的日变化特征,白天影响程度明显强于夜间且在午后的影响最强;太湖在午后引起湖区及邻近地区低层大气显著降温和异常辐散,抑制了该区域的大气对流活动并引起对流降水的明显减少,进而造成夏季太湖及邻近地区降水的减少。

The WRF model was used to numerically simulate the local climatic effect of Taihu lake in summer, moreover, the impact of Taihu lake on the local surface air temperature, precipitation and the related possible physical mechanisms were revealed. Results show that the Taihu lake mainly tends to re- gionally make the summer surface air temperature and precipitation decrease and the intensity is weake- ning rapidly from the lake to the surrounding areas. The precipitation reduced by Taihu lake is mainly at- tributed to the decreasing convective precipitation. The impact of the Taihu lake on the surface tempera- ture and precipitation over the lake and surrounding regions presents obvious diurnal variations, which is stronger in day than in night and the strongest effect is at afternoon. The reduced temperature and anoma- lous divergence at the lower troposphere over the lake and surrounding areas induced by Taihu lake suppresses the convective activity and further decreases the precipitation over these regions.