Observed holiday aerosol reduction and temperature cooling over East Asia

摘要

The air pollution in Chinese Spring Festival (CSF) period over eastern China was investigated using the long-term observations from 2001 to 2012 over 323 stations. The dominant feature of the pollutants around the CSF holidays is the significant reduction of concentration. During the 10day period around the CSF (but excluding the Lunar New Year's Day, LNYD), PM10 experiences a reduction of -9.24. In association with the aerosol reduction, temperature significantly drops over eastern China. From the third day before the LNYD to the second day after, the daily mean temperature anomaly is -0.81 degrees C, and for no-rain days the anomaly is -0.85 degrees C. The simultaneous anomalies of the daily maximum and minimum temperatures are -0.79 degrees C and -0.82 degrees C, respectively. From the third day to seventh day after the LNYD, the significant negative temperature anomalies move out of China, extending to a broad area from the South China Sea to the western North Pacific. Between the 8th and the 12th days, the significant temperature anomalies can still be found over 140 degrees E-160 degrees E and 15 degrees N-25 degrees N. The reduced downward longwave flux might play an important role in holiday cooling. The possible atmospheric feedback is discernable. The thermal and circulation configuration accompanying the cooling favors baroclinic interaction between upper and lower troposphere for the midlatitude cyclone. The anomalous cyclone becomes mature during the third to the seventh day after the LNYD and disappears 12 days later. The anomalous northern winds in association with the cyclone decrease the temperature and also help disperse the holiday aerosols over eastern China.