Sea ice processes in the Russian Arctic seas in autumn of 2021 and estimation of ice forecasts accuracy

Sea ice processes in the autumn season of 2021 have been analyzed. It is shown that formation of new ice began 5-15 days later than normal in all the Russian Arctic seas. Estimation of long-term forecast accuracy has revealed that dates of freeze-up and reaching ice thickness values of 20-25 cm were predicted successfully in the Laptev and East Siberian seas (100%); prediction was not successful in the Chukchi Sea. The overall accuracy of ice forecasts in autumn season was 75%. The accuracy of short-term forecast of ice conditions type within 28 NSR regions has been estimated. It is shown that the accuracy of forecast of all the key criteria determining sea ice conditions type varied between 85 and 95%; the accuracy of forecast of ice conditions type varied between 90 and 95%. In conclusion, it is noted that, when navigating in ice, it is important to use background information on the expected sea ice tendencies as additional to specialized sea ice and hydrometeorological support.