Visibility Trends in 11 Cities of Hebei Province During 1960-2002
FAN Yin-Qi 1, LI Er-Jie 1, and FAN Zeng-Lu 2 1 Meteorological Institute of Hebei Province, Shijiazhuang 050021 2 Climate Center of Hebei Province, Shijiazhuang 050021
Visibility data have been examined for 11 cities’ meteorological stations in Hebei Province. The trends of visibility from 1960 to 2002 have been analyzed by using three different statistical methods: cumulative percentiles, Ridit analysis, and frequency of “very good” visibility. The result shows that from north to south of Hebei Province, the distribution character of visibility is from high to low. The visibility of 11 cities has declined notably over the past 43 years, and the largest range of visibility declining is in summer. The turning period of visibility change took place during 1979-1981, and both the visibility and “very good visibility” frequency of the 11 cities decreased rapidly at that time. This is consistent with the economic development. During 1998-2002, the visibility had a rising trend in Shijiazhuang, Chengde, Qinhuangdao, Tangshan and Handan, and remained unchanged in Cangzhou, Xingtai, Langfang and Zhangjiakou, but declined continually in Baoding and Hengshui.
【CateGory Index】： P463.3