Interannual variability of the Indian monsoon and the Southern Oscillation

Journal Article · Wed Jan 01 04:00:00 EST 1986 · Arch. Meteorol., Geophys., Bioclimatol., Ser. B: Climatol., Environ. Meteorol., Rad. Res.; (United States)

DOI:https://doi.org/10.1007/BF02263132· OSTI ID:6724106

Wu, M; Hastenrath, S

Years with abundant Southwest monsoon rainfall in India are characterized by anomalously low pressure over South Asia and the adjacent waters, enhanced cross-equatorial flow in the western, and increased cloudiness over the northern portion of the Indian Ocean, continuing from the pre-monsoon through the post-monsoon season; positive temperature anomalies over land and in the Arabian Sea in the pre-monsoon season, changing to negative departures after the monsoon onset. The following causality chain is suggested: the anomalously warm surfaces of south Asia and the adjacent ocean in the pre-monsoon season induce a thermal low, thus enhancing the northward directed pressure gradient, and favoring a vigorous cross-equatorial flow over the Indian Ocean. After the monsoon onset the land surfaces are cooled by evaporation, and the Arabian Sea surface waters by various wind stress effects. However, latent heat release over South Asia can now maintain the meridional topography gradients essential to the monsoon circulation. The positive phase of the Southern Oscillation (high pressure over the Eastern South Pacific) is associated with circulation departures in the Indian Ocean sector similar to those characteristic of years with abundant India monsoon rainfall. Abundant rainfall over India during the northern summer monsoon leads the positive mode of the southern Oscillation, and this in turn leads Java rainfall, whose peak is timed about half a year after that of India. A rising Southern Oscillation tendency presages abundant India Southwest Monsoon rainfall but a late monsoon onset. 46 references, 9 figures, 4 tables.

• Research Organization: Univ. of Wisconsin, Madison
• OSTI ID: 6724106
• Journal Information: Arch. Meteorol., Geophys., Bioclimatol., Ser. B: Climatol., Environ. Meteorol., Rad. Res.; (United States), Journal Name: Arch. Meteorol., Geophys., Bioclimatol., Ser. B: Climatol., Environ. Meteorol., Rad. Res.; (United States) Vol. 36; ISSN AGBRD
• Country of Publication: United States
• Language: English

Related Subjects

500100* -- Environment
Atmospheric-- Basic Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AMBIENT TEMPERATURE
ANNUAL VARIATIONS
ARABIAN SEA
ASIA
ATMOSPHERIC PRESSURE
CLOUDS
DEVELOPING COUNTRIES
DISASTERS
ENVIRONMENTAL EFFECTS
EVAPORATION
INDIA
INDIAN OCEAN
MONSOONS
PHASE TRANSFORMATIONS
SEAS
SOUTHERN OSCILLATION
STORMS
SURFACE WATERS
VARIATIONS
WIND