Accession Number : AD0819959

Title :   SOME ASPECTS OF THE ONSET OF THE SUMMER MONSOON OVER SOUTHEAST ASIA.

Descriptive Note : Technical rept. no. 2 (Final) on Southeast Asia Monsoon Study,

Corporate Author : COLORADO STATE UNIV FORT COLLINS DEPT OF ATMOSPHERIC SCIENCE

Personal Author(s) : Orgill, M. M. ; Riehl, Herbert

Report Date : MAR 1967

Pagination or Media Count : 75

Abstract : The following aspects of the onset of the monsoon over Southeast Asia have been investigated: (1) definition of the onset of the summer monsoon and determination of calendar dates of onsets; (2) role of tropical cyclones during the onset of the summer monsoon; (3) seasonal changes in the upper air circulation over Asia during onsets, and possible differences between late and early onset years; and (4) influence of seasonal heating and changes in the thermodynamic structure of the atmosphere during onsets. The onset of the summer monsoon over Southeast Asia was defined by an abrupt fracture of the equatorial shearline at 10,000 feet, which allows equatorial (monsoon) westerlies to penetrate northward into southern China. The 29-year mean calendar date of this seasonal event was generally established at 17 May with a range of 33 days. Differential heating of land and ocean areas and tropical cyclogenesis in the Bay of Bengal are the principal starting mechanisms of the summer monsoon; however, certain extratropical circulation features are contributing factors. Tropical cyclones, through converting latent heat to sensible heat and potential energy, may at times modify the tropospheric environment producing favorable thermal and dynamic conditions for the establishment of the summer monsoon circulation over Southeast Asia.

Descriptors :   (*METEOROLOGICAL PHENOMENA, SOUTHEAST ASIA), TROPICAL CYCLONES, ATMOSPHERIC MOTION, TIME, THERMAL RADIATION, TROPOSPHERE, JET STREAMS, CLIMATE, NORTHERN HEMISPHERE, RAINFALL, PERIODIC VARIATIONS, WEATHER STATIONS, ATMOSPHERIC TEMPERATURE, HEAT TRANSFER, METEOROLOGICAL CHARTS, WIND.

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE