Long-term atmospheric visibility, sunshine duration and precipitation trends in South China

Abstract

The fast industrialization and urbanization in South China have led to increasing concentration of aerosols, which has caused the degradation of atmospheric visibility and substantially impacted on cloud properties and the initiation of precipitation in this region. Therefore, it is valuable to study the spatial and temporal trends of atmospheric visibility, sunshine duration and precipitation in recent years in the region to understand how aerosols affect the environment. In this article, meteorological data of 28 stations in South China were obtained from the China Meteorological Data Sharing Service System and were analyzed using several different statistical methods. The stations were divided into four categories: prefecture, county, neighbor, and remote stations. The data show a decrease of visibility in 93% of the stations during 1980–2012, among which the neighbor stations have recorded the fastest average decrease of −1.8 km/decade. The average visibility for all the stations over the 33 years is 16.8 km and the total average decreasing rate is −1.3 km/decade. The percentages of “high” visibility in prefecture, county and neighbor stations decreased dramatically, while the percentages of “low” visibility in aforementioned stations were much higher than those in the remote stations. As for the sunshine duration, the neighbor stations have recorded the rapidest decrease in the recent 30 years, while the data of the prefecture stations showed the most significant change during 1957–2012. The annual average daily rainfall of rainy days shows a significant increase during 1978–1985 in the dry seasons and 1990–2000 in the wet seasons, respectively. The percentage of rainy days per year had been decreasing linearly during 1980–2010. Light rain days had been decreasing in all the types of stations, though such change is the smallest in remote stations. Meanwhile, torrential rain and rainstorm days have been increasing, especially in the prefecture stations. By using the empirical orthogonal function (EOF) and detrended cross-correlations analysis (DCCA), we may conclude that visibility and rainfall have cross-correlation, which shows more complex multifractal structure in Guangzhou (a prefecture station) than in Gaoyao (a neighbor station) and Lianping (a remote station).