Severe winter weather as a response to the lowest Arctic sea-ice anomalies
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Severe winter weather as a response to the lowest Arctic sea-ice anomalies CHEN Hongxia1 , LIU Na1∗ , ZHANG Zhanhai2 1
Key Laboratory of Marine Science and Numerical Modeling, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China 2 Key Laboratory for Polar Science, Polar Research Institute of China, State Oceanic Administration, Shanghai 200136, China Received 15 December 2011; accepted 6 March 2013 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2013
Abstract Possible impact of reduced Arctic sea-ice on winter severe weather in China is investigated regarding the snowstorm over southern China in January 2008. The sea-ice conditions in the summer (July–September) and fall (September–November) of 2007 show that the sea-ice is the lowest that year. During the summer and fall of 2007, sea ice displayed a significant decrease in the East Siberian, the northern Chukchi Sea, the western Beaufort Sea, the Barents Sea, and the Kara Sea. A ECHAM5.4 atmospheric general circulation model is forced with realistic sea-ice conditions and strong thermal responses with warmer surface air temperature and higher-than-normal heat flux associated with the sea-ice anomalies are found. The model shows remote atmospheric responses over East Asia in January 2008, which result in severe snowstorm over southern China. Strong water-vapor transported from the Bay of Bengal and from the Pacific Ocean related to Arctic sea-ice anomalies in the fall (instead of summer) of 2007 is considered as one of the main causes of the snowstorm formation. Key words: Arctic sea ice, severe winter weather, ECHAM5.4 atmospheric general circulation model Citation: Chen Hongxia, Liu Na, Zhang Zhanhai. 2013. Severe winter weather as a response to the lowest Arctic sea-ice anomalies. Acta Oceanologica Sinica, 32(10): 11-15, doi: 10.1007/s13131-013-0360-y
1 Introduction The Arctic sea ice has declined dramatically at least over the past 30 a, with the most extreme decline seen in the summer melting season (e.g., Comiso, 2006; Stroeve et al., 2008). Entering the 21st century, summer sea-ice decline accelerated by a reduction of 3% to 10% every 10 a (Stroeve et al., 2007; Comiso et al., 2008). The amount of sea ice reached its lowest in the summer of 2007, with 4.13×106 km2 , 36% below the average from 1979 to 2006. When high-albedo ice is replaced by low-albedo ocean surface in summer, there is significantly more net solar radiation on the surface, increasing the heat stored in the upper ocean. This heat stored during the summer retards the recovery of the sea ice during the fall freeze-up period (e.g., Deser et al., 2000). Fluxes of sensible and latent heats in the atmosphere increase over a warmer ocean, which can exert some influences back on the atmosphere in the following winter (e.g., Honda et al., 2009; Petoukhov and Semenov, 2010). It is well known that in the context of global warming in recent years, frequent occurrences of severe weather spread all over the world. In the case of China, since 200
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