近年华北平原跨年污染过程的气象条件影响及预报技术研究
Capture and Analysis of Heavy Pollution Process in an Environmental Air Quality Forecast in North China
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摘要: 近年来, 华北中南部的河南和山东中西部地区连续多年出现了跨年重污染过程。这种重污染过程的形成与近年来出现的独特气候条件密切相关。以2022年底至2023年初的一次跨年重污染过程为例, 从预报经验的角度分析了在这种情况下可能影响环境空气质量的5种气象条件因子的作用。同时, 对不同层级气象产品进行了区间定位和分型解读, 旨在通过对冬季华北地区气象条件因子的分型, 进而掌握捕捉重污染过程的方法。应用数值模拟预报技术对重污染过程进行模拟, 使用嵌套网格空气质量预报模式系统(NAQPMS)数值预报模型进行预测模拟和准确率评估, 并结合比对预报员人工订正后的空气质量指数(AQI)级别准确率进行模型验证。研究结果表明, 在重污染过程捕捉中, 研究地区的高空受脊区或者均压场控制、地面受均压场控制、风速较弱且风向并非偏西或偏北、湿度较大且无强降水的时候, 重污染过程较易形成。NAQPMS数值模式的72 h预报结果对于华北地区不同省份的捕捉命中率不一。预报员对于区域整体的预测准确程度在重污染过程前期偏低, 对于豫南准确率可以达到100%, 但是豫中北地区准确率仅达到50%。Abstract: In recent years, a series of cross-year heavy pollution episodes have occurred consecutively in the central and southern regions of North China, specifically in Henan Province and the central-western regions of Shandong Province. The uniqueness of such heavy pollution episode is closely related to the unique climate conditions that have emerged in recent years. Taking a cross-year heavy pollution episode from the end of 2022 to the beginning of 2023 as an example, the potential roles of five meteorological factors which may influence the environmental air quality during the heavy pollution episode were analyzed in the present study from the perspective of forecasting experience. Different levels of meteorological products were positioned and classified in different intervals, attempting to grasp the methods for capturing heavy pollution episode by classifying meteorological factors in North China during winter. Meanwhile, numerical simulation prediction technology were employed to simulate heavy pollution episode. The NAQPMS model was used for predicting and evaluating the accuracy, which was further validated by comparing with the accuracy of the AQI level manually corrected by forecasters. As a result, heavy pollution episode is more likely to take place when the high altitude of the area is controlled by ridge or pressure equalization fields, the ground is controlled by pressure equalization fields, the wind speed is relatively lower with the direction being not west or north, and the humidity is relatively higher and no heavy precipitation. The NAQPMS numerical model simulations on the 72 hour forecast in the present study show varying capture success rates for different provinces in North China. While the overall capture success rates for the whole region of the forecasters is relatively lower at the initial stages of the process, with only 50% for central and northern Henan, but up to 100% for southern Henan.