Some Aspects of Indian Monsoon Depressions and the Associated Rainfall

Abstract

Abstract This study is based on all the monsoon depressions that moved westward across India between Calcutta, Allahabad, and Delhi on the right and Gopalpur, Nagpur, and Ahmadabad on the left during July and August for the period 1891–1960. Statistical distribution, of 24-hr motion and of the intensity of the depression, the relation between 24-hr motion and concurrent 24-hr rainfall, and the relation between the intensity of the depression and subsequent 24-hr rainfall are examined. In addition, the average rainfall per depression day and its standard deviation, the contribution of depression rainfall to the total rainfall, and the efficiency of the depression as a rain giver are computed. Mean patterns of 24-hr rainfall within 500 km of the center of the depression along longitudes 87°E, 80°E, and 75°E are obtained, and the main points of difference between them are discussed. In the quadrants to the right of the depression track, the rainfall field is flat. In the quadrants to the left, however, large...