Analysis and comparison of heat flux of landfast ice during 2016 in the Prydz Bay, Antarctica

Abstract

Long term in situ atmospheric observation of the landfast ice nearby Zhongshan Station in the Prydz Bay was performed from April to November 2016. The in situ observation, including the conventional meteorological elements and turbulent flux, enabled this study to evaluate the sea ice surface energy budget process. Using in situ observations, three different reanalysis datasets from the European Centre for Medium-Range Weather Forecasts Interim Re-analysis (ERA-Interim), National Centers for Environmental Prediction Reanalysis2 (NCEP R2), and Japanese 55-year Reanalysis (JRA55), and the Los Alamos sea ice model, CICE, output for surface fluxes were evaluated. The observed sensible heat flux (SH) and net longwave radiation showed seasonal variation with increasing temperature. Air temperature rose from the middle of October as the solar elevation angle increased. The ice surface lost more energy by outgoing longwave radiation as temperature increased, while the shortwave radiation showed obvious increases from the middle of October. The oceanic heat flux demonstrated seasonal variation and decreased with time, where the average values were 21 W/m2 and 11 W/m2, before and after August, respectively. The comparisons with in situ observations show that, SH and LE (latent heat flux) of JRA55 dataset had the smallest bias and mean absolute error (MAE), and those of NCEP R2 data show the largest differences. The ERA-Interim dataset had the highest spatial resolution, but performance was modest with bias and MAE between JRA55 and NCEP R2 compare with in situ observation. The CICE results (SH and LE) were consistent with the observed data but did not demonstrate the amplitude of inner seasonal variation. The comparison revealed better shortwave and longwave radiation stimulation based on the ERA-Interim forcing in CICE than the radiation of ERA-Interim. The average sea ice temperature decreased in June and July and increased after September, which was similar to the temperature measured by buoys, with a bias and MAE of 0.9°C and 1.0°C, respectively.