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相对湿度是制约雾与霾形成和转换以及影响能见度的最关键环境气象参数。而海陆热力差异是影响我国东部及沿海雾霾天气的重要气候背景。立足于中国大陆东部和沿海地区所处的地理环境,综合海陆热力差异这一要素,从低层大气环流变化及水汽输送等角度,对相对湿度多时空尺度的变化及其热动力成因和机制进行了尝试性分析。结果表明,50多年来,中国东部冬季海陆热力差异主要形成于我国长江以南地区和黑潮(包括源区黑潮和东海黑潮)以东海域。由此构建的海陆温差指标显示,该纬向海陆热力差异存在显著的准7年和准4年的年际变化以及准17年的年代际变化,同时还有明显的长期增强趋势,其主要与我国长江中游地区-黄淮流域-华北地区及以东沿海一线(负相关区)和华南地区(正相关区)的相对湿度变化密切关联。其中,冬季纬向海陆热力差异的减弱(增强),主要造成低空季风环流的西南风(东北风)异常,进而调控源自孟加拉湾东部和我国南海海域(东中国海及以东海域)的水汽向我国大陆东部的输送,并可通过制约水汽输送和降水等形式影响以上地区相对湿度的变化。纬向海陆热力差异的增强很可能引起华北等地区相对湿度的减小,而导致华南地区相对湿度的显著增加,反之亦然。此成果可为明确重点区域相对湿度变化与雾霾发生发展的关系和未来演变等研究工作的深入开展,以及为有关雾霾天气的预测预警报服务提供必要的科学依据和保障。
Relative humidity is the most critical environmental meteorological parameter that restricts the formation and conversion of fog and haze and affects visibility. The difference between sea and land heat is an important climatic background that affects the haze weather in eastern China and the coastal areas. Based on the geographical environment in the eastern and coastal areas of mainland China and the integration of the differences in the thermal power between land and sea, the changes of multi-temporal and spatial scales of relative humidity and the causes and mechanisms of their thermodynamics were studied from the perspective of lower atmospheric circulation and water vapor transport Tentative analysis The results show that in the past 50 years, the difference in winter sea-land heat in eastern China mainly occurs in the area to the south of the Yangtze River and the area to the east of the Kuroshio (including the Kuroshio in the source area and the Kuroshio in the East China Sea). The land-sea temperature difference index constructed by this method shows that there are significant interannual variations of quasi-seven years and quasi-four years and quasi-17-year interdecadal variations of the latitudinal land-sea heat differences, and there is also a clear long-term enhancement trend. The main and The change of relative humidity in the middle reaches of Yangtze River-Huanghe-Huaihe River Basin-North China and the coastline (negative-related area) and the southern China (positive-correlated area) are closely related. Among them, the weakened (enhanced) difference in winter latitudinal sea-land thermal differences mainly caused the anomaly of the southwest wind (northeast wind) in the low-level monsoon circulation, and then regulated the water vapor directions originating from the east of the Bay of Bengal and the waters of the South China Sea (East China Sea and the east of the East China Sea) The transportation in the eastern part of the mainland of China can affect the relative humidity in the above areas by restricting the modes of water vapor transport and precipitation. The increase in zonal thermal-land-sea differences is likely to cause a decrease in relative humidity in North China and other regions, leading to a significant increase in relative humidity in southern China and vice versa. The results can provide a scientific basis and guarantee for clarifying the relationship between the change of relative humidity in key areas and the occurrence and development of smog haze and the future development of the haze weather.