天津一次雾过程的边界层特征研究

Analysis on Characteristics of Atmospheric Boundary Layer During a Fog Process in Tianjin

雾作为边界层内一种特殊的天气现象与边界层结构有着密切联系。本文利用天津边界层梯度观测平台分析2010年11月28日至12月2日一次雾过程的边界层结构特征。结果表明:此次过程雾Ⅰ阶段水汽最先在离地面80～100 m的高度凝结,雾Ⅱ(平流雾)阶段水汽由上往下传输;雾Ⅰ前,大气有明显的逆温,雾Ⅱ前大气处于不稳定状态,雾中大气趋于中性,在雾变薄过程中,边界层气象塔可观测到雾顶的强逆温;雾中长波辐射达到平衡,净长波辐射为0,可用此区分水雾和霾;雾对光化学烟雾有抑制作用,NO_x和小粒子会出现累积,影响人体健康。

The fog is a kind of special weather phenomenon and is closely related with structures of the at- mospheric boundary layer. Based on the Tianjin boundary gradient observation system, we have analyzed a fog process from November 28 to December 2, 2010, which can be divided into two episodes, fog I and fog II. The results showed that： first the condensation of water was found from 80 to 100 m heights during fog I and then vapor was transported downward during fog 1I. There was obvious inversion temperature before fog ~[ and unstable atmosphere before fog II. While fog 11 happened, the atmospheric status was tending to be neutral, and there was a strong inversion temperature at the top of fog. Analysis on charac- teristics of radiation and pollution during fog process shows that, there was a long-wave radiation equilibri- um, an inhibition effect to the photochemical smog, and an accumulated effect of small particle and NOx during fog.