基于地基遥感资料的厦门市污染边界层特征分析

城市大气边界层是影响城市环境气象的重要研究对象,本研究利用新型地基遥感数据针对城市颗粒物污染过程开展边界层特征分析,旨在利用风廓线雷达和微波辐射计等高时空分辨率的遥感数据探讨边界层内大气运动、温湿条件的变化与近地面污染累积的关系.结果表明:厦门地区颗粒物污染过程中,边界层内弱风层厚度较地面风速而言更能够代表边界层内扩散条件的变化,可以更好地表征和预测近地面污染的变化;在局地累积的污染过程中,边界层内存在较厚的弱风层,同时2 km以下的风场有明显的风向转变特征,导致边界层内不存在有效的传输和扩散,另外,污染时边界层垂直温差可以在一定程度上反映干季的垂直扩散条件,0～3 km温差与PM_(2.5)浓度有着密切的联系;冷空气过程有将上游污染物向本地区输送的可能,城市边界层在东北大风的条件下伴随着显著的垂直下沉运动,有利于上空污染向下扩散.多源地基遥感数据联合分析能够进一步解释城市边界层内气象条件对于城市大气污染变化的影响,集合各设备的探测优势开展城市宜居和污染气象条件研究具有较高的科学性和可行性.

Analysis of urban boundary layer characteristics based on ground-based remote sensing data in Xiamen

The planet boundary layer (PBL) could be an important research subject for environmental meteorology in urban regions. Focus on discussing the relationship between variations of atmospheric motion, temperature conditions under boundary layer and accumulations of near-surface pollutants by using high spatial and temporal resolution data, such as the wind profile radar and the microwave radiometer. The thickness of weak wind layer within PBL represented the near-surface condition of diffusion better than wind speed in surface layer. The deep weak wind layer in PBL along with diurnal variation of weak wind direction under the 2 km height indicated non-effective transport and diffusion in PBL, and the vertical difference of temperature within 3 km existed close connection with surface PM_2.5 concentrations, and also represented vertical diffusion of atmosphere in PBL in local particle accumulation episodes during dry season. The appearance of obviously descending motion during cold front processes with the strong northeastern wind in PBL, could be favor of the exogenous particle transport from upper layer to surface. Combination of the advantages of each multi-source observation devices could further understand the influence of urban boundary layer variation to atmospheric environment, and researches on the Livable City and urban meteorological environment applied by new type remote sensing devices are high feasibility and scientificity.