Open AccessPreferred Modes of Variability and Their Relationship with Climate Change
Author(s) -
Seung Woo Son,
Sukyoung Lee
Publication year - 2006
Publication title -
journal of climate
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.315
H-Index - 287
eISSN - 1520-0442
pISSN - 0894-8755
DOI - 10.1175/jcli3705.1
Subject(s) - predictability , empirical orthogonal functions , climatology , zonal flow (plasma) , northern hemisphere , middle latitudes , geology , mode (computer interface) , atmospheric circulation , zonal and meridional , latitude , atmospheric sciences , climate model , environmental science , climate change , physics , geodesy , plasma , quantum mechanics , computer science , tokamak , operating system , oceanography
Spatial structure of annular modes shows a remarkable resemblance to that of the recent trend in the observed circulation (Thompson et al.). This study performs a series of multilevel primitive equation model simulations to examine the extent to which the annular mode is capable of predicting changes in the zonal-mean flow response to external heat perturbations. Each of these simulations represents a statistically steady state and differs from each other in the values of the imposed tropical heating (ℋ) and high-latitude cooling (). Defining the annular mode as the first empirical orthogonal function (EOF1) of zonal-mean tropospheric zonal wind, it is found that the “climate predictability” is generally high in the small –large ℋ region of the parameter space, but is markedly low in the large –small ℋ region. In the former region, EOF1 represents meridional meandering of the midlatitude jet, while in the latter region, EOF1 and EOF2 combine to represent coherent poleward propagation of zonal-mean flow anomalies. It is also found that the climate predictability tends to be higher with respect to changes in than to changes in ℋ. The implications of these findings for the Southern Hemisphere climate predictability are also presented.