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Global structure of the Madden-Julian Oscillations during two recent contrasting summer monsoon seasons over India

Vernekar, AD and Thapliyal, V and Kripalani, RH and Singh, SV and Kirtman, B (1993) Global structure of the Madden-Julian Oscillations during two recent contrasting summer monsoon seasons over India. Meteorology and Atmospheric Physics, 52 (1-2). pp. 37-47.

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Abstract

The global nature of the Madden-Julian Oscillations (MJOs) have been investigated by applying a frequency filter to daily data for the summer monsoon months (June to September) during two contrasting years-1987, a deficient monsoon year and 1988, an excess monsoon year. Several meteorological parameters at five levels in the troposphere have been examined. Regions with large amplitude of these oscillations are isolated for each year. The results indicate that the global spatial distribution of these oscillations is more in a deficient year than in an excess year, in particular over the Indian subcontinent and the EI Niño Southern Oscillation (ENSO) regions. The principal modes of variability during these two years have been investigated through Empirical Orthogonal Functions (EOFs). The first two eigenmodes of 850 hPa zonal wind explain nearly 50 of the variance. The dipole type of structure between the Indian and the Pacific region is more apparent in 1987 than in 1988. Time-longitude cross sections of the filtered zonal wind over the equatorial regions clearly show that eastward propagation is detected in 1987, but is virtually absent in 1988. It is also seen that the 30-60 day filtered winds are stronger during the monsoon of 1987 than in 1988.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer-Verlag
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 15 May 2015 09:08
Last Modified: 15 May 2015 09:08
URI: http://moeseprints.incois.gov.in/id/eprint/1076

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