The effects of radiative transfer in maintaining the Indian summer monsoon
- North Carolina State Univ., Raleigh, NC (United States)
Atmospheric radiative transfer is an important thermodynamic forcing for the Indian summer monsoon. The monsoon is a component of a larger scale circulation system the principal components of which are the Hadley cell and the Walker Circulation. The Hadley cell is a thermally direct circulation that transports heat toward the poles. In the northern hemispheric summer, the ascending branch of the Hadley cell moves northward, due to heating of the land masses. This ascending branch of the Hadley cell is referred to as the Intertropical Convergence Zone (ITCZ). The return branch of the Hadley cell is characterized by southwesterly surface winds. At the surface, the ITCZ is marked by convergence of southwesterly surface winds from the south and northeasterly surface winds from the north. As the ITCZ moves northward, the southern extent of the northerly surface winds also moves northward, and southerly surface winds from the south side of the ITCZ also move northward. The surface convergence at the ITCZ is a driving mechanism for the summer monsoon circulation. The northward drift of the Hadley cell in the northern summer ITCZ is the deep convection over the warm pool of water in the western tropical Pacific ocean, located at about 160E. The latent heating in the deep convection drives another direct circulation, known as the Walker Circulation. The upper branch of the Walker Circulation over south Asia is easterly winds created by the deep convection in the western tropical Pacific. Convective activity over the Indian peninsula interacts with the Walker Circulation, creating a jet structure over the western part of India and the eastern Arabian Sea. This structure is known as the Tropical Easterly Jet (TEJ). Secondary circulations associated with the Indian convection also help to maintain the baroclinicity, which is essential to the development of monsoon depression, the maintenance of the monsoon trough, and the circulation and hydrology of the region in general.
- Research Organization:
- USDOE Office of Energy Research, Washington, DC (United States). Environmental Sciences Div.
- OSTI ID:
- 83186
- Report Number(s):
- CONF-940277--; ON: DE95009951
- Country of Publication:
- United States
- Language:
- English
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