北京市2013年1月一次空气重污染过程分析

采用数值模式与观测资料相结合的方式，对北京市2013年1月9～15日一次空气重污染过程的大气环境背景、气象条件和形成原因进行了初步分析。结果表明，此次重污染过程北京市空气质量从9日的二级跳至10日五级重度污染，11日一13日空气质量维持连续3d严重污染，14日降为重度污染，15日转为轻度污染；重污染过程期间10—14日P（PM2.5）平均值为323μg／m。，平均风速为1．47m／s，平均相对湿度为73．6％，24h变温基本为一2．72～2．68℃，24h平均变压为一3．65～2．63hPa。指出，此次重污染过程与当地气象条件密切相关，稳定的大气环流形势为污染的持续提供了大气环流背景，风速较小、湿度较大、边界层较低、持续逆温是造成重污染的主要原因，地面风场辐合及边界层下沉运动是造成重污染的重要原因。

Analysis about the Characteristics and Formation Mechanism of a Serious Pollution Event in January 2013 in Beijing

In this paper, the meteorology of a typical air pollution episode in Beijing City was investigated by combining observed data and the WRF meteorology model from January 9 th to 15 th ,2013. The weather conditions, atmospheric environmental back- ground and mechanism of formation about this heavy air pollution were all analyzed. The results showed that during this serious air pollution incident, the air quality index in Beijing jumped to the level five from 9th to l Oth,maintained level six from 1 lth to 13th, reduced to level five in 14th and ended in 15th with level three. The average concentration of PM2.5 was 323μg/m^3 from January 10th to 14th ; the ground meteorological elements characterized mainly as average wind （1.47m/s） , average humidity（73.6% ） , 24 h average temperature transformer（ - 2.72 - 2.68℃ ） and 24 h average pressure transformer（ - 3.65 - 2.63 hPa）. The situation was closely related to the local meteorological conditions; the stable atmospheric circulation continuously provided favorable environmental field for this heavy air pollution. Small wind speed, high humidity, low PBL, lasting inversion layer were the main reasons for this heavy air pollution incident and ground wind convergence, sinking motion in the boundary layer were the important causes of this heavy air pollution incident.