The impact of radiosonde data on forecasting sea?￠????ice distribution along the Northern Sea Route during an extremely developed cyclone

摘要

To investigate the impact of radiosonde data on the sea?￠????ice forecast in the Northern Sea Route during an extremely developed cyclone on 6 August 2012, a series of numerical experiments were conducted using an ice?￠????ocean coupled model with fine horizontal resolution (approximately 2.5 km). The atmospheric forcing data used for the model were forecast data with (CTL) and without (OSE) initialization by radiosonde data over the Fram Strait, obtained by the German R/V Polarstern , and the European Centre for Medium?￠????Range Weather Forecasts Interim reanalysis data. All numerical experiments were run from 06:00 UTC on 3 August 2012 to 00:00 UTC on 8 August 2012 with an initial sea?￠????ice concentration and thickness derived from the Advanced Microwave Scanning Radiometer 2 satellite data. The root?￠????mean?￠????square error and correlation coefficient for the sea?￠????ice distribution showed that the CTL simulation predicted better the sea?￠????ice distribution in the Northern Sea Route than the OSE simulation. This occurred in particular from 6 to 7 August when the cyclone became strong. The thermodynamic processes resulted in the difference in the sea?￠????ice thickness due to changes in the vertical energy fluxes. However, the differences in the sea?￠????ice concentration and velocity were caused mainly by the dynamics, particularly the difference in wind fields, rather than the thermodynamics. These results suggest that radiosonde data are effective in improving the forecast accuracy of the sea?￠????ice distribution. Therefore, errors in the weather forecast data would have a substantial impact on the safety of ship navigation and the sea?￠????ice distribution.