ABSTRACT:

Data sets of SSM/I (Special Sensor Microwave Imager) were used to study the inter-annual variability of sea ice area (SIA) in Pacific sector of the Arctic. The results show that SIA in this region has the most significant inter-annual variability in summer and experiences a frequency shift during 1979–2008. The main atmospheric patterns were studied using sea level pressure (SLP) grid data from NCEP/NCAR. The three leading EOF modes of SLP behave as north/south SLP anomaly seesaw, Aleutian Low pressure, and west/east SLP anomaly seesaw in the Arctic. The time series of the first two modes are similar to AO (Arctic Oscillation) and NPI (North Pacific Index) respectively. While the AO had a high correlation with the SIA in Pacific sector of the Arctic during 1992–1997, the NPI performed much better than the AO after 2001 in the correlation with SIA. An index called WED which represents the SLP difference between west and east Arctic in Pacific sector has a high correlation with the SIA in our study region after 2004. These large scale atmospheric patterns contribute to SIA variability for different time periods.

INTRODUCTION

Under global warming conditions, sea ice in the Arctic Ocean has changed rapidly over the last 30 years. Because of its unique properties such as high albedo and heat insulation, sea ice plays an important role in coupled air-ice-sea system. As a result, Arctic sea ice variability and its controlling mechanism, as well as its effects on the climate of the northern hemisphere and the whole earth, have become an important research topic of the global climate change. Data from remote sensing indicates that the trend of sea ice area (SIA) has abruptly decreased after the year 1990 (Parkinson et al., 1999; Rigor et al., 2004; Shimada et al., 2006).

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