Links between the Amundsen Sea Low and sea ice in the Ross Sea: seasonal and interannual relationships
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Previous studies have shown that sea ice extent in the Southern Ocean is influenced by the intensity and location of the Amundsen Sea Low (ASL), through their effect on the meridional winds. However, the inhomogeneous nature of the influence of the ASL on sea ice as well as its influence during critical periods of the sea ice annual cycle is not clear. In this study, we do a spatio-temporal analysis of links between the ASL and the sea ice during the advance and retreat periods of the ice over the period 1979–2013 focusing on the role of the meridional and zonal winds. We use the ERA-Interim monthly-averaged 500 mb geopotential height and 10 m wind data along with monthly Passive Microwave Sea Ice Concentrations (SIC) to examine the seasonal and interannual relationships between the ASL and SIC in the Ross–Amundsen sea ice sector. To characterize the state of the ASL we use indices that describe its location and its intensity. We show that the ASL has preferred locations and intensities during ice advance and retreat seasons. The strength and direction of the influence of the ASL are not spatially homogeneous and can change from advance to retreat season and there are strong significant relationships between the characteristics of the ASL and SIC, within and across seasons and interannually.
KeywordsCryosphere Antarctic sea ice variability Amundsen Sea Low Sea ice-atmosphere interaction
We are grateful to J. Scott Hosking for making the ASL indices data available (https://legacy.bas.ac.uk/data/absl/) and to ECMWF for the provision of reanalysis fields (http://apps.ecmwf.int/datasets/data/interim-mdfa/) and to the U.S. National Snow and Ice Data Center for providing sea ice data (http://nsidc.org/data/docs/daac/nsidc0079_bootstrap_seaice.gd.html). MMH and LL acknowledge funding from the Frontiers of Earth System Dynamics (FESD) grant 1338814 from the U. S. National Science Foundation and from the National Aeronautics and Space Administration (NASA), grant #1048926.
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