The magnitude of the effect of air pollution on sunshine hours in China

This study investigates the changes in sunshine hours in relation to API (Air Pollution Index) across China. Data were collected from a total of 38 cities over the period of 1960–2009. Sunshine hours in over 84% of the cities significantly (p < 0.05) decline with an average of 16.7% for the 1960s–2000s. This decline is mainly prevalent over Sichuan Basin (22.4%), North China Plain (18.8%), and Yangtze River Delta (18.2%). While the sunshine hour decline is largely in the 20th century (with the strongest drop in the 1980s and the least in the 1990s), it rebounds by 0.3% after 2000. For especially in winter seasons and the North China region, API is negatively related with sunshine hours. For days with API > 80, sunshine hours are on the average 0.7 h d−1 (8.4%) shorter than for days with API ≤ 80 under clear‐sky condition for 2001–2005. In cities with average daily API ≤ 80 and >80 for the 2000s, sunshine hour decline for the 1960s–2000s is 0.8 h d−1 (13.4%) and 1.0 h d−1 (15.9%) respectively. Winter seasons with high API (90) exhibit the highest sunshine hour decline (21.5%). The study shows that spatiotemporal changes in sunshine hours in China could largely be explained in terms of API. Key Points Air pollution negatively influences sunshine hour variation API is a critical indicator in studying air pollution effect on sunshine hours Sunshine hours significantly decline 16.7% for the 1960s‐2000s in 86% of China