A linear model study of the mid-tropospheric ridge and its displacement -inclusion of a surface heat sink

Abstract

ABSTRACT. A linear model of the steady response of a stratified fluid to isolated heat sources is used to study the mainlAinence of the mean position of the mid-tropospheric ridge and its displacement. There is evidence from recent observational studies that the winter/spring snow cover over Eurasia is negatively related to the April 500 hPa ridge position along 75~. In our earlier study, we proposed a possible physical mechanism of the southward displacement of the mid-tropospheric ridge. In this study the anomalous cooling associated with the increased snow cover in Eurasia is considered as a heat sink (extending to the surface), north of the tropical heat sources. It is demonstrated that such a surface heat sink can also result in significant southward displacement of the mid-tropospheric ridge.