Relationship between Atmospheric Pollution Processes and Atmospheric Circulation in Shanghai, China

Abstract:

Severe haze weather occurred in Shanghai in the beginning of 2013. In this paper，spatial-temporal characteristics of the smog days was analyzed using the data of 10 stations in the downtown, the suburb & the outer suburb of Shanghai from 2002-2013. In addition, we discussed the correlation between PM_2.5, PM₁₀, SO₂ & NO₂ and the smog days. At last, the situation of atmospheric circulation during a severe haze weather process between Jan, 2, 2013 to Feb, 4, 2013 was studied. Results show that: (1) from 2002 to 2012, the average smog days in Shanghai and in the outer suburb of Shanghai show a trend of fluctuating decrease generally with the rates of 6.031d/a and 5.89d/a, respectively. The smog days in the downtown of Shanghai decrease most quickly, with the rate of 15.418d/a. The smog days in the suburb of Shanghai decreased most slowly, with the rate of 2.495d/a. Smog happens most frequently in January, November and December (accounting for 31%) and least in August and September. The inter-annual variation of smog days shows the trend of decreasing in all four seasons. The smog days decreases most slowly in spring, with the ratio of 1.16d/a, it decreases most quickly in winter, with the ratio of 1.65d/a, and decreases at the medium ratio of 1.58d/a and 1.49d/a in summer and autumn respectively. (2) The number of monthly average smog days is positively related to the monthly average concentration of PM₁₀, SO₂, PM_2.5 and NO₂. The correlative coefficient between the number of monthly average smog days and the monthly average PM₁₀ and NO₂ concentrations are 0.756 and 0.610, respectively. (3) Atmospheric circulation analysis shows that stable west straight current in the air, weak high pressure on the ground and sufficient supplement of water steam are good for the formation and maintenance of haze weather.