Enhanced residual mean circulation during the evolution of split type sudden stratospheric warming in observations and model simulations

Journal of earth system science

Semjon Schimanke^3¹  Ulrich Cubasch^1²  Sourabh Bal^1,2³  Thomas Spangehl^4⁴ 

[1] Department of Physics, Swami Vivekananda Institute of Science and Technology, Kolkata, India^2;German Weather Service, Offenbach am Main, Germany^4;Institute for Meteorology, Freie Universitat, Berlin, Germany^1;Swedish Meteorological and Hydrological Institute, Norrk¨oping, Sweden^3

关键词: Split events;    stratospheric sudden warming;    residual mean circulation;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Residual mean circulation changes during the evolution of sudden stratospheric warming (SSW) are investigated by composite analyses of 76 major warming events identified in a present day simulation performed with a coupled ocean–troposphere–stratosphere model from 299 winters. Their dynamical signatures are compared with the 17 SSW events identified from 35 years of Era-Interim data. The main difference is that, relative frequency of simulated SSW events is smaller than that obtained from reanalysis. SSW events are classified as displacement or split events based on the geopotential field values at 10 hPa. The geopotential field values identify 10 and 3 split events in simulation and observationrespectively. The model quite accurately simulates some of the dynamical features associated with the major SSW. Residual mean circulation induced by EP-flux divergence, sum of advection and residual forcing are stronger in split events than in displacement type SSW has been confirmed by both simulation and observation. Moreover, the contribution of EP-flux divergence or planetary wave forcing is larger than the contribution of other types of forcing.

【 授权许可】

CC BY