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- Author or Editor: Deng-Yi Gao x
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Abstract
The heating of the Plateau of Tibet (the Qinghai-Xizang Plateau) has been deemed to play an important role in the development and movement of the South Asian anticyclone which, to a great extent, affects the Indian monsoon development. In this paper the heating effects are estimated from synoptic data from that region for April 1979. During the transition season warming over the plateau interacts with advected synoptic systems and induces the South Asian high, normally located south of the Himalayas during that season, to develop strongly and shift northward.
Abstract
The heating of the Plateau of Tibet (the Qinghai-Xizang Plateau) has been deemed to play an important role in the development and movement of the South Asian anticyclone which, to a great extent, affects the Indian monsoon development. In this paper the heating effects are estimated from synoptic data from that region for April 1979. During the transition season warming over the plateau interacts with advected synoptic systems and induces the South Asian high, normally located south of the Himalayas during that season, to develop strongly and shift northward.
Abstract
As a result of the high mountains to the west and north of the plateau and the control by westerly mean flow in spring, hot and dry conditions are often observed over the southeastern edge of the Tibetan Plateau (SETP), favoring occurrences of extreme heat events there. Indeed, maximum centers and remarkable increasing trends of extreme heat (EH) days in spring are found over the region. Springtime EH events over the SETP also exhibit strong interannual variability and are closely linked to a spring-type circumglobal teleconnection (SCGT) pattern, which is the second leading mode of 200-hPa meridional wind over the North Hemisphere in spring. This SCGT shows distinctive features from the traditional circumglobal teleconnection patterns found in boreal summer and winter. It manifests as a circumglobally navigated Rossby wave train along the mid–high latitudes, which splits to a north branch along the polar jet and a south branch along the subtropical jet over Eurasia after propagating through the North Atlantic Ocean. The two branches eventually reach the SETP, forming an anomalous anticyclonic circulation over the region. Hence, conditions in the SETP are controlled by significant anomalous subsidence and a clearer sky, resulting in below-normal rainfall and above-normal air temperature, favoring more EH events in the region. The SETP EH events are also closely linked to the spring-type CGT-like pattern in April and May but not in March. In addition, the influence of the foehn effect on the SETP EH is discussed.
Abstract
As a result of the high mountains to the west and north of the plateau and the control by westerly mean flow in spring, hot and dry conditions are often observed over the southeastern edge of the Tibetan Plateau (SETP), favoring occurrences of extreme heat events there. Indeed, maximum centers and remarkable increasing trends of extreme heat (EH) days in spring are found over the region. Springtime EH events over the SETP also exhibit strong interannual variability and are closely linked to a spring-type circumglobal teleconnection (SCGT) pattern, which is the second leading mode of 200-hPa meridional wind over the North Hemisphere in spring. This SCGT shows distinctive features from the traditional circumglobal teleconnection patterns found in boreal summer and winter. It manifests as a circumglobally navigated Rossby wave train along the mid–high latitudes, which splits to a north branch along the polar jet and a south branch along the subtropical jet over Eurasia after propagating through the North Atlantic Ocean. The two branches eventually reach the SETP, forming an anomalous anticyclonic circulation over the region. Hence, conditions in the SETP are controlled by significant anomalous subsidence and a clearer sky, resulting in below-normal rainfall and above-normal air temperature, favoring more EH events in the region. The SETP EH events are also closely linked to the spring-type CGT-like pattern in April and May but not in March. In addition, the influence of the foehn effect on the SETP EH is discussed.
