CR 39:149-157 (2009)  -  DOI: https://doi.org/10.3354/cr00820

ABSTRACT: There has been a drastic decline in sunshine hours in North China since the 1960s. Increased aerosol emissions driven by air pollution have been identified as the cause of sunshine decline in the region. The present study investigates the possible impact of wind speed on the extent of decline in sunshine hours in Shijiazhuang, Beijing and Tianjin (3 major cities in North China) during the period from 1960–2008. Among these cities, the smallest (largest) decline in sunshine hours was in the city with the highest (lowest) wind speed: Beijing (Shijiazhuang). Annual and monthly average daily sunshine hours for 1960–1969 (a period with low anthropogenic pollution and slow socioeconomic development) and 1999–2008 (a period with high anthropogenic pollution and rapid socioeconomic development) are compared with respect to low and high wind speeds. Extent of sunshine hours showed a positive correlation with wind speed. Analysis of the API (air pollution index) from 2000–2008 shows a discernible effect of wind speed on atmospheric pollution. Thus, we conclude that the decline in sunshine hours in the region is heavily influenced by wind speed. Low dispersion of air pollutants and their aerosol derivatives under low wind speed are likely the cause of the decline in sunshine hours.

KEY WORDS: Decline in sunshine hours · Wind speed · Air pollution · Aerosol