The Easterly Jet Stream in the Tropics

Abstract

It is shown that in summer an easterly jet stream overlies southern Asia in the high troposphere with core near I$"'.This current is quasi-geostrophic. Below the level of strongest winds temperatures decrease from right to left across the current looking downstream; above the level of strongest wind (150-100 mb) the reverse is true. Distribution of cloudiness and precipitation in the lower monsoon correspond to that noted in association with westerly jet streams in the temperate zone: precipitation downstream from the region with the highest winds to left of the axis, upstream to the right.The foregoing holds on individual days and climatically during the monsoon season as a whole. Since an easterly jet stream is observed only over southern Asia (and Africa), but not over the Pacific and Atlantic oceans, it is suggested that the current originates in connection with the large-scale arrangement of land masses and oceans, and with the elevated heat source of the Tibetan plateau.

Effect of changing tropical easterly jet, low level jet and quasi‐biennial oscillation phases on Indian summer monsoon

“…West phase years 1953, 1955, 1957, 1961, 1966, 1969, 1971, 1973, 1975, 1978, 1980, 1985, 1990, 1995, 1997, 1999, 2002, 2006, 2008East phase years 1954, 1956, 1958, 1960, 1962, 1963, 1965, 1968, 1970, 1972, 1974, 1976, 1977, 1979, 1981, 1982, 1984, 1986, 1987, 1989, 1991, 1992, 1994, 1996, 1998, 2000, 2001, 2003, 2005, 2010, 2012 methods, EMD is empirical, intuitive, direct and adaptive (Wu and Huang, 2009). The main idea of EMD is to decompose the data locally into different oscillatory components called IMF.…”

“…Different physical mechanisms accountable for the maintenance of the TEJ are found in literature. Koteswaram (1958) and Flohn (1964) related the low level monsoonal flow and rainfall to the variation in intensity of the TEJ. Previous study by Krishnamurti and Bhalme (1976) observed that the cumulus convection results in latent heat release which leads to coupling of the lower level circulation with the upper level circulation.…”

“…The presence of low level jet (LLJ) at lower level (850 hPa) and tropical easterly jet (TEJ) at upper level (100 hPa) characterizes the ISM within the troposphere. The first detailed study on TEJ was carried out by Koteswaram (1958). TEJ having a wind speed of 40-50 m s −1 and strongest winds over the Arabian Sea during the Northern Hemispheric summer (Reiter, 1961) is a key feature of the ISM circulation and can be observed in the months of June, July, August and September (JJAS) at 100-150 hPa (Krishnamurti and Bhalme, 1976).…”

Effect of SST Variation on ITCZ in APE Simulations

“…Associated with this, there is an upper level zonal wind maximum in the form of a strong easterly jet with its core at 12°N, i.e., about 13° southward of the primary continental rainbelt along the seasonal monsoon trough over India and 13° north of the maritime ITCZ. This is a strong monsoon component and a prominent large-scale monsoon circulation feature called the tropical easterly jet (TEJ), which is observed only over the Indian longitudes during the summer monsoon season (Koteswaram 1958). A meridional section of zonal wind velocity at 70°E based on ERA-40 is shown in Fig.…”

Seasonal Weather Variations in Khumbu Himal

“…ii) The thermal effect as a heat source during the monsoon season, producing a strong thermal anticyclone called the Tibetan High (Yeh, 1950;Murakami, 1958;Koteswaram, 1958;Flohn, 1968;Murakami, 1970) and also to cause the northward shift of the STJ.…”