Role of intra-seasonal oscillations in modulating Indian summer monsoon rainfall     

Ashwini Kulkarni  Ramesh Kripalani  Sudhir Sabade  Madhavan Rajeevan 《Climate Dynamics》2011,36(5-6):1005-1021

The day-to-day behavior of Indian summer monsoon rainfall (IMR) is associated with a hierarchy of quasi-periods, namely 3?C7, 10?C20 and the 30?C60?days. These two periods, the 10?C20?days and the 30?C60?days have been related with the active and break cycles of the monsoon rainfall over the Indian sub-continent. The seasonal strength of Indian summer monsoon rainfall may depend on the frequency and duration of spells of break and active periods associated with the fluctuations of the above intra-seasonal oscillations (ISOs). Thus the predictability of the seasonal (June through September) mean Indian monsoon depends on the extent to which the intra-seasonal oscillations could be predicted. The primary objective of this study is to bring out the dynamic circulation features during the pre-monsoon/monsoon season associated with the extreme phases of these oscillations The intense (weak) phase of the 10?C20 (30?C60) days oscillation is associated with anti-cyclonic circulation over the Indian Ocean, easterly flow over the equatorial Pacific Ocean resembling the normal or cold phase (La Nina) of El Nino Southern Oscillation (ENSO) phenomenon, and weakening of the north Pacific Sub-tropical High. On the other hand the weak phase of 10?C20?days mode and the intense phase of 30?C60?days mode shows remarkable opposite flow patterns. The circulation features during pre-monsoon months show that there is a tendency for the flow patterns observed in pre-monsoon months to persist during the monsoon months. Hence some indications of the behavior of these modes during the monsoon season could be foreshadowed from the spring season patterns. The relationship between the intensity of these modes and some of the long-range forecasting parameters used operationally by the India Meteorological Department has also been examined.  相似文献   

Solar Activity,Lightning and Climate     

Devendraa Siingh  R. P. Singh  Ashok K. Singh  M. N. Kulkarni  A. S. Gautam  Abhay K. Singh 《Surveys in Geophysics》2011,32(6):659-703

The physics of solar forcing of the climate and long term climate change is summarized, and the role of energetic charged particles (including cosmic rays) on cloud formation and their effect on climate is examined. It is considered that the cosmic ray-cloud cover hypothesis is not supported by presently available data and further investigations (during Forbush decreases and at other times) should be analyzed to further examine the hypothesis. Another player in climate is lightning through the production of NO_x; this greenhouse gas, water vapour in the troposphere (and stratosphere) and carbon dioxide influence the global temperature through different processes. The enhancement of aerosol concentrations and their distribution in the troposphere also affect the climate and may result in enhanced lightning activity. Finally, the roles of atmospheric conductivity on the electrical activity of thunderstorms and lightning discharges in relation to climate are discussed.  相似文献   

Wind speed prediction using statistical regression and neural network   总被引：1，自引：0，他引：1  

Makarand A. Kulkarni  Sunil Patil  G. V. Rama  P. N. Sen 《Journal of Earth System Science》2008,117(4):457-463

Prediction of wind speed in the atmospheric boundary layer is important for wind energy assessment, satellite launching and aviation, etc. There are a few techniques available for wind speed prediction, which require a minimum number of input parameters. Four different statistical techniques, viz., curve fitting, Auto Regressive Integrated Moving Average Model (ARIMA), extrapolation with periodic function and Artificial Neural Networks (ANN) are employed to predict wind speed. These methods require wind speeds of previous hours as input. It has been found that wind speed can be predicted with a reasonable degree of accuracy using two methods, viz., extrapolation using periodic curve fitting and ANN and the other two methods are not very useful.  相似文献   

IMPACT OF HUMIDITY DATA ON THE PREDICTION OF ONSET VORTEX WITH A LIMITED AREA MODEL          下载免费PDF全文

Anuradha Kulkarni  S. S. Vaidy  S. S. Singh 《Acta Meteorologica Sinica》1992,6(4):511-518

A limited area model has been applied to study the impact of satellite-derived relative humidity data on the predic-tion of onset vortex of monsoon 1979.The results show that inclusion of satellite-derived relative humidity data im-proved the prediction of track of the cyclonic circulation and the rainfall rates in the region of the vortex.  相似文献   

Very low frequency (VLF) chorus emissions: A topical survey     

V. H. Kulkarni  Jharana Das 《Surveys in Geophysics》1992,13(1):35-46

In this paper we have tried to present, coherently, a review of the observations of natural VLF radio emissions, termed chorus, that have been made on the ground and aboard satellites, and also their dependence on various geomagnetic phenomena. We have highlighted current theoretical interpretations of the generation and propagation of chorus signals.  相似文献   

The three-point correlation function of luminous red galaxies in the Sloan Digital Sky Survey     

Gauri V. Kulkarni  Robert C. Nichol  Ravi K. Sheth  Hee-Jong Seo  Daniel J. Eisenstein  Alexander Gray 《Monthly notices of the Royal Astronomical Society》2007,378(3):1196-1206

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An atmospheric electrical method to determine the eddy diffusion coefficient     

M. N. Kulkarni  A. K. Kamra 《Journal of Earth System Science》2010,119(1):87-96

The ion-aerosol balance equations are solved to get the profiles of atmospheric electric parameters over the ground surface in an aerosol-rich environment under the conditions of surface radioactivity. Combining the earlier results for low aerosol concentrations and the present results for high aerosol concentrations, a relation is obtained between the average value of atmospheric electric space charge in the lowest ～2 m, the surface electric field and eddy diffusivity/aerosol concentration. The values of eddy diffusivity estimated from this method using some earlier measurements of space charge and surface electric field are in reasonably good agreement with those calculated from other standard methods using meteorological or electrical variables.  相似文献   

A Study Of Coherent Structures In The Atmospheric Surface Layer Over Short And Tall Grass     

L. K. Sadani  J. R. Kulkarni 《Boundary-Layer Meteorology》2001,99(2):317-334

Ejection and sweep eddy motions are coherent structures in the atmospheric surface layer. These structures are responsible for surface-layer fluxes of sensible heat and momentum. This study analyzes these structures over the same surface in short and tall grass situations. It is shown that momentumsweep eddy motions are dominant in both short and tall grass situations. Theratio between eddy structures revealed that the small-scale eddies are activatedin tall grass conditions. The study applies to unstable conditions duringdaytime.  相似文献   

Estimation of probable maximum precipitation for catchments in eastern India by a generalized method   总被引：1，自引：0，他引：1  

P. R. Rakhecha  B. N. Mandal  A. K. Kulkarni  N. R. Deshpande 《Theoretical and Applied Climatology》1995,51(1-2):67-74

Summary A generalized method to estimate the probable maximum precipitation (PMP) has been developed for catchments in eastern India (80° E, 18° N) by pooling together all the major rainstorms that have occurred in this area. The areal raindepths of these storms are normalized for factors such as storm dew point temperature, distance of the storm from the coast, topographic effects and any intervening mountain barriers between the storm area and the moisture source. The normalized values are then applied, with appropriate adjustment factors in estimating PMP raindepths, to the Subarnarekha river catchment (upto the Chandil dam site) with an area of 5663 km². The PMP rainfall for 1, 2 and 3 days were found to be roughly 53 cm, 78 cm and 98 cm, respectively. It is expected that the application of the generalized method proposed here will give more reliable estimates of PMP for different duration rainfall events.With 5 Figures  相似文献   

Program to Calculate Hydraulic Conductivity Using Dugwell Recovery Data     

Anil Lalwani  Himanshu Kulkarni  S. B. Deolankar  P. Paul Thomas 《Ground water》1995,33(1):144-147

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