Changes in atmospheric blocking characteristics within Euro-Atlantic region and Northern Hemisphere as a whole in the 21st century from model simulations using RCP anthropogenic scenarios

An analysis of simulations using the IPSL-CM5 climate model of general circulation shows the ability of this model to reproduce the current climate of the main blocking characteristics obtained from reanalysis data, including number of blocking events and their duration, intensity and frequency. Possible changes of blocking characteristics in the Euro-Atlantic region (EA) and for the Northern Hemisphere (NH) as a whole are estimated from model simulations with the RCP2.6 and RCP8.5 scenarios for the 21st century. Results of the model simulations show a general increase in the blocking frequency for the EA in winter, summer and for the entire year during the 21st century for both analyzed RCP scenarios, while changes of the opposite sign are characteristic for NH as a whole. It is also noted that there is a tendency for an increase in the blocking intensity in the EA during the winter from model simulations with both analyzed RCP scenarios for the 21st century. A significant increase is obtained in the EA for the likelihood of extreme winter with the total blocking duration longer than seven weeks. Also, a similar tendency is characteristic for the EA summer.