This study compares the impacts of interarmual Arctic sea ice loss and ENSO events on winter haze days m mare- land China through observational analyses and AGCM sensitivity experiments. The results suggest that （1）...This study compares the impacts of interarmual Arctic sea ice loss and ENSO events on winter haze days m mare- land China through observational analyses and AGCM sensitivity experiments. The results suggest that （1） Arctic sea ice loss favors an increase in haze days in central-eastern China; （2） the impact of ENSO is overall contained within southern China, with increased （reduced） haze days during La Nifia （El Nifio） winters; and （3） the impacts from sea ice loss and ENSO are linearly additive. Mechanistically, Arctic sea ice loss causes quasi-barotropic positive height anomalies over the region from northem Europe to the Ural Mountains （Urals in brief） and weak and negative height anomalies over the region from central Asia to northeastem Asia. The former favors intensified frequency of the blocking over the regions from northern Europe to the Urals, whereas the latter favors an even air pressure distribu- tion over Siberia, Mongolia, and East Asia. This large-scale circulation pattern favors more frequent occurrence of calm and steady weather in northern China and, as a consequence, increased occurrence of haze days. In comparison, La Nifia （El Nifio） exerts its influence along a tropical pathway by inducing a cyclonic （anticyclonic） lower-tropo- spheric atmospheric circulation response over the subtropical northwestern Pacific. The northeasterly （southwesterly） anomaly at the northwestern rear of the cyclone （anticyclone） causes reduced （intensified） rainfall over southeastern China, which favors increased （reduced） occurrence of haze days through the rain-washing effect.展开更多
基金Supported by the Strategic Project of the Chinese Academy of Sciences(XDA11010401)China Meteorological Administration Special Public Welfare Research Fund(GYHY201306026)National(Key) Basic Research and Development(973)Program of China(2015CB453202 and 2016YFA0601802)
文摘This study compares the impacts of interarmual Arctic sea ice loss and ENSO events on winter haze days m mare- land China through observational analyses and AGCM sensitivity experiments. The results suggest that （1） Arctic sea ice loss favors an increase in haze days in central-eastern China; （2） the impact of ENSO is overall contained within southern China, with increased （reduced） haze days during La Nifia （El Nifio） winters; and （3） the impacts from sea ice loss and ENSO are linearly additive. Mechanistically, Arctic sea ice loss causes quasi-barotropic positive height anomalies over the region from northem Europe to the Ural Mountains （Urals in brief） and weak and negative height anomalies over the region from central Asia to northeastem Asia. The former favors intensified frequency of the blocking over the regions from northern Europe to the Urals, whereas the latter favors an even air pressure distribu- tion over Siberia, Mongolia, and East Asia. This large-scale circulation pattern favors more frequent occurrence of calm and steady weather in northern China and, as a consequence, increased occurrence of haze days. In comparison, La Nifia （El Nifio） exerts its influence along a tropical pathway by inducing a cyclonic （anticyclonic） lower-tropo- spheric atmospheric circulation response over the subtropical northwestern Pacific. The northeasterly （southwesterly） anomaly at the northwestern rear of the cyclone （anticyclone） causes reduced （intensified） rainfall over southeastern China, which favors increased （reduced） occurrence of haze days through the rain-washing effect.
