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This study employ Wavelet analysis to investigate the winter (May-Aug) rainfall variability with respect to the intensity of Indian Ocean Subtropical High Pressure (IOSHPS) System and its longitude, Indian Ocean Subtropical High Longitudes (IOSHLN), positions. The physical relationship among these predictors and winter rainfall were analyzed using composites of atmospheric circulation patterns. We have found inverse association between IOSH indices and winter rainfall. We have observed that maximum rainfall variability occurred in 1-3 years periodicity during 1951-1979 when IOSHPS was located around Southern Australia. This caused moisture onshore and Victoria received more rainfall. We have also observed that highest variability from 1980-2016 with similar periodicity in IOSHPS. The shifting of IOSHPS from Southern to Southeastern Australia and increase in its intensity from the post 1979 period of the analysis era (1951-2016) cause further declined in winter rainfall over Victoria.

Aims: To explore the association between observed frequency of anticyclones over subtropical Indian Ocean (10°S-50°S, 102.5°E-142.5°E) and average autumn rainfall over the districts of Tasmania. Methodology: We have divided the rainfall amounts over nine districts of Tasmania into three categories (Above average, average and below average rainfall) by using z-scores technique for each autumn (March-May) month for the period of 1951-2016. We have also categorized the calculated frequency of anticyclone over the subtropical Indian Ocean in a similar fashion. Results: Our analysis suggests inverse association between each category of average rainfall and the corresponding frequency of anticyclones for each month of autumn. This association revealed that during below average rainfall, the high frequencies of anticyclones were occupied over the most of the area of subtropical Indian Ocean that resulted less rainfall in the districts while during above average autumn rainfall, the high frequencies of anticyclones observed in the west of 110°E this enabled more autumn rainfall over the districts. We have also found the negative correlation coefficients between mean sea level pressure over the same domain of Indian Ocean and average rainfall over each district in each month of the autumn (March-May). Conclusion: The slightly shift of Mean Central Pressure (MCP) to the north from the west coast of Tasmania from March-May enabled the extra-tropical activity of rainfall systems. This causes enhanced rainfall during average and above average rainfall conditions than March-April over nine districts of Tasmania.

This study assesses the inter-annual variability of summer monsoon rainfall of Northern Hilly Area of Pakistan, which includes Balakot, Chitral, Murree, Gilgit, Skardu, Chilas, Muzaffarabad and Dir. The region receives a heavy rainfaU, the total annual rainfall being 1000 mm or more. We attempt to model the rainfall process of the data from 1971-2000. Initially we use twelve predictors out of which only four, viz., sea surface temperature (SST-lOa), temperature of Hyderabad city of Pakistan (HT-5)and pressure of Kakul (KP-10)and Lahore (LP-3), are selected with the help of stepwise multiple linear regression. The mean square error of the regression model is found to be 13.8%. Since the entire modeling procedure is based on selected predictors, we suggest that the selected predictors, which are selected here according to their correlation, should be refined by using more sophisticated technique such as principal component analysis, or nonlinear correlations.

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