During the 25th Chinese National Antarctic Research Expedition,GPS radiosondes were launched to detect the atmospheric vertical structure over the southeast Indian Ocean frontal region.Some low-level characteristics along the cruise are studied based on in-situ observation.The observations reveal that vertical distributions of the low-level wind field and air temperature field on both sides of the Subantarctic Front are very different.A stronger(weaker) vertical gradient is on the cold(warm) side,which demonstrates that the mid-latitude ocean-atmosphere interaction is active in the southeast Indian Ocean frontal region.A low-level jet is observed over the Subantarctic Front,with speed up to 14 m.s-1.For the Antarctic polar front,low-level wind speed near the sea surface is greater than that aloft,in contrast with the situation of the Subantarctic Front.Comparing satellite remote sensing data and widely-used reanalysis datasets with our in-situ observations,differences of varying magnitudes are found.Air temperature from Atmospheric Infrared Sounder(AIRS) data has a limited difference.The European Center for Medium Range Weather Forecasts Interim Re-Analysis(ERA Interim) dataset is much more consistent with the observations than the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) Reanalysis 1 in the southeast Indian Ocean frontal region.
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