Meridional transport of sensible heat in contrasting monsoon activity: Spherical harmonic analysis

• Main Authors: Awade, ST, Bawiskar, SM
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Birkhauser 1982
• Subjects: Meteorology and Climatology; North Pole; South Pole; South pole
• Online Access: http://moeseprints.incois.gov.in/1321/; http://link.springer.com/article/10.1007%2FBF00877034

Spherical harmonic analysis is made of the grid point values of geopotential heights at 700 mb and 300 mb levels for the months April to August for the years 1967 and 1972. The year 1967 is a good monsoon year and 1972 is a bad monsoon year in India. Meridional transport of sensible heat is obtained in wave number domain using spherical harmonic coefficients at 500 mb level for m=1 to 10 and n-m=0 to 10, where m represents the wave number round the globe and n-m gives the numbers of zero points from north pole to south pole excluding the poles themselves. Large northward transports of sensible heat in the month of May and in the monsoon months at the subtropics are characteristic of bad monsoon. Wave 1 transports sensible heat southward (for n-m=0) and wave 2 transports sensible heat northward (for n-m=4). Strengthening of wave 1 is conducive to good monsoon year and strengthening of wave 2 is conducive to bad monsoon year. These are the same features obtained in Fourier analysis. The contrasting features exist in waves 1 and 2 both in good and in bad monsoon and are better defined in the present analysis than in the Fourier analysis of the earlier study. However, waves 1 and 2 reveal clearer contrast in the present analysis than in the Fourier analysis. Bad monsoon activity is associated with large divergence of heart at subtropics and large convergence of heat at extra tropics.