RELATIONSHIP BETWEEN HORIZONTAL EXTINCTION COEFFICIENT AND PM_(10) CONCENTRATION IN XI'AN, CHINA, DURING 1980-2002

摘要

Based on daily visibility data obtained from 1980-2002 and air pollution index data from 2001-2004 in Xi'an, long-term variations and relationships for daily horizontal extinction coefficient and mass concentration of PM_(10) have been evaluated. A decreasing trend was found in horizontal extinction coefficient during the past 23 years, with higher values observed in 1980s relative to 1990s, and the highest and lowest values in winter and summer, respectively. Significant correlation and similar seasonal variations existed between horizontal extinction coefficient and PM_(10) concentration, suggesting the high influence of PM_(10) to the visibility drop at a site in the Guanzhong Plain of central China during the past two decades.