南京一次辐射雾过程的边界层特征
The Boundary Layer Structures of the Radiation Fog in Nanjing
中文摘要：
选取2007年12月13—14日南京一次辐射雾的外场观测资料及NCEP的2.5°×2.5°NC再分析资料和GDAS全球1°×1°气象资料，从天气形势背景、气象要素以及物理量场等方面，探讨雾形成和持续的主要边界层物理和天气学成因；并利用HYSPLIT-4轨迹模式对此次雾过程进行后向轨迹分析。分析表明：（1）此次雾过程期间始终存在逆温层，甚至出现多层逆温。逆温层的存在，使大气层结更加稳定，利于雾的形成和发展。（2）此次辐射雾过程水汽输送较平流辐射雾小，水汽来源主要来自本地辐射降温后的水汽凝结。（3）此次雾过程地面受高压控制，低层水汽通量散度为正值，近地面有弱辐散，利于辐射降温水汽凝结，而持续的水汽辐散造成的水汽流出以及雾后期随着北部干冷空气南下使得这次辐射雾寿命较短。
中文关键词：
雾，大气边界层，水汽通量，HYSPLIT-4后向轨迹
KeyWords：
fog, atmospheric boundary layer, water vapor flux, HYSPLIT-4 backward trajectory
Abstract：
A detailed analysis of the synoptic situation, meteorological fields was made to get the features of the boundary layer during the fog events which occurred on December 13-14, 2007 by the observation field data, NCEP’s 2.5°×2.5°NC reanalysis data and GDAS Global 1°×1°meteorological data. The results show that: (1) The presence of inversion layer, even multi-layer inversion throughout the fog events, indicates that the atmosphere is more stable, which was conducive to the convergence of water vapor before fog formation, then not favorable for the divergence of water vapor after fog formation, which helped the development and maintenance of the fog. (2) The water vapor flux transported in radiation fog was smaller than the advectionradiation one, and the water vapor in radiation fog was mainly from the local moisture condensation. (3) The surface was dominated by high pressure, during the radiation fog event, the divergence of water vapor flux was always positive, indicating that the water vapor near the surface was easy to be held and conducive to radiation cooling during the radiation fog event, while the divergence of water vapor flux and the northern cold air made the fog life a little too short.