Program

In the recent decade the Arctic sea ice has been observed to undergo a remarkable decline. Some people think it’s because the enhanced inflow of warm Pacific and Atlantic water into the Arctic. Recent studies revealed that the enhanced downward infrared radiation (IR) caused by poleward transport transport of warm moisture are also important for the recent Arctic sea ice loss. A recent study indicated that the enhanced frequency of Ural blocking (UB) during 2000-2013 can amplify the Arctic warming. Thus, the UB is more likely to have an important effect on the Arctic sea ice loss. The aim of the present study is to use the sea ice concentration (SIC) data in winter (DJF) ranging from December 1979 to February 2015 from the National Snow and Ice Data Center (NSIDC) datasets and reanalysis data such as surface air temperature and 500-hPa geopotential height are taken from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis 1 datasets for 1979-2015 to reveal how the UB affects the Arctic sea ice decline to infer their causality. Besides downward infrared radiation (IR), surface sensible heat flux (SHF), latent heat flux (LHF), cloud cover and evaporation are also taken into consideration. To reveal the physical process of the Arctic warming and blocking variability, zonal mean wind is regarded as an indicator of the strength of eddy forcing in the zonal flow which directly effects the characteristics of blocking such like strength, location and duration. In this study, the relationship between sea ice loss and the onset of UB is clarified by daily observation and the physical process involved enhenced IR downward and LHF is understood better by estimating the contributions in warm the SAT in the lifecycle of UB. Furthermore, the results seem to be modulated by the interdecadal variability of North Atlantic Oscillation (NAO) in interdecadal time scale.