• P V Puranik

      Articles written in Journal of Earth System Science

    • Energetics of lower tropospheric planetary waves over mid latitudes: Precursor for Indian summer monsoon

      S M Bawiskar M D Chipade P V Puranik U V Bhide

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      Based on NCEP/NCAR reanalysis data, kinetic energy and momentum transport of waves 0 to 10 at 850 hPa level are computed from monthly mean zonal (u) and meridional (v) components of wind from equator to 90‡N. Fourier technique is used to resolve the wind field into a spectrum of waves. Correlation analysis between All India Seasonal Monsoon Rainfall (AISMR) and energetics of the waves indicates that effective kinetic energy of waves 1, 3 and 4 around 37.5‡N in February has significant correlation (99.9%) with the subsequent AISMR. A simple linear regression equation between the effective kinetic energy of these three waves and AISMR is developed. Out of 47 years’ (1958–2004) data, 32 years (1958–1989) are utilized for developing the regression model and the remaining 15 years (1990–2004) are considered for its verification. Predicted AISMR is in close agreement with observed AISMR. The regression equation based on the dynamics of the planetary waves is thus useful for Long Range Forecasting (LRF) of AISMR. Apart from the regression equation, the study provides qualitative predictors. The scatter diagram between AISMR and effective kinetic energy of waves 1, 3 and 4 around 37.5?N indicates that if the kinetic energy is more (less) than 5m2s-2, the subsequent monsoon will be good (weak). Stream function fields indicate that high latitude trough axis along 40‡E (70‡E) leads to a good (weak) monsoon over India.

    • Energetics of lower tropospheric ultra-long waves: A key to intra-seasonal variability of Indian monsoon

      S M Bawiskar M D Chipade P V Puranik

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      Analysis of fifty four (1951-2004)years of daily energetics of zonal waves derived from NCEP/ NCAR wind (𝑢 and 𝑣 data and daily rainfall received over the Indian landmass (real time data) during southwest monsoon season (1 June-30 September)indicate that energetics (momentum transport and kinetic energy)of lower tropospheric ultra-long waves (waves 1 and 2)of low latitudes hold a key to intra-seasonal variability of monsoon rainfall over India.

      Correlation coefficient between climatology of daily (122 days)energetics of ultra-long waves and climatology of daily rainfall over Indian landmass is 0.9.The relation is not only significant but also has a predictive potential.The normalised plot of both the series clearly indicates that the response period of rainfall to the energetics is of 5-10 days during the onset phase and 4-7 days during the withdrawal phase of monsoon over India.During the established phase of monsoon, both the series move hand-in-hand.Normalised plot of energetics of ultra-long waves and rainfall for individual year do not show marked deviation with respect to climatology.These results are first of its kind and are useful for the short range forecast of rainfall over India.

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