scholarly journals District-level forecast of northeast monsoon rainfall over Tamilnadu using Indian Ocean dipole mode index

MAUSAM ◽  
2021 ◽  
Vol 62 (2) ◽  
pp. 229-234
Author(s):  
O.P. SINGH ◽  
ONKARI PRASAD
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Lead Time ◽  
Monsoon Rainfall ◽  
District Level ◽  
Annual Rainfall ◽  
Northeast Monsoon ◽  
Dipole Mode ◽  
Indian Ocean Dipole Mode ◽  
Northeast Monsoon Rainfall

The northeast monsoon season (October-December) contributes a substantial percentage of annual rainfall over Tamilnadu. The present paper describes a method for prediction of northeast monsoon rainfall (NEMR) over Tamilnadu on smaller spatial scale, i.e., district-level with sufficient lead time. Tamilnadu has been divided into ten homogeneous clusters of districts and the predictions are made for each cluster with lead times of two and one months using Indian Ocean dipole mode (IODM) index. A stronger western pole of IODM during August-September is associated with enhanced northeast monsoon activity over most of the districts of Tamilnadu. The predictions on the basis of regressions developed from NEMR and IODM index data have been validated for six years from 1997-2002. For many districts the mean errors between actual (realized) and predicted rainfall are within ±10%. Hence, using IODM index, it is possible to predict the NEMR activity over most of the districts of Tamilnadu with a lead time of two months, with only exception of NEMR over Kanyakumari which is not significantly correlated to IODM phenomenon.

scholarly journals Relationship between Indian Ocean dipole mode and summer monsoon

MAUSAM ◽  
2021 ◽  
Vol 59 (2) ◽  
pp. 167-172
Author(s):  
INDU BALA ◽  
O. P. SINGH
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Ocean Dipole ◽  
Summer Monsoon Rainfall ◽  
Monsoon Onset ◽  
Dipole Mode ◽  
Peninsular India ◽  
Indian Ocean Dipole Mode ◽  
The Indian Ocean ◽  
Withdrawal Phase

Utilizing the Indian Ocean Dipole Mode (IODM) and Indian Summer Monsoon Rainfall (ISMR) data for the period 1960-2002 the relationships between the IODM and monsoon onset over Kerala and rainfall distribution over the country have been studied. It has been found that stronger/weaker western pole during April-May is associated with delayed/early monsoon onset over Kerala. Stronger eastern pole during March-April seems to be associated with enhanced seasonal (June-September) rainfall over peninsular India. The IODM index of July-August can provide good indications of summer monsoon activity over peninsular India during the withdrawal phase of the  monsoon, i.e., during September.

scholarly journals Trend and change point detection of seasonal rainfall for effective crop planning over southern transition zone of Karnataka, India

2021 ◽  
Vol 23 (3) ◽  
pp. 316-323
Author(s):  
S. SRIDHARA ◽  
PRADEEP GOPAKKALI
Keyword(s):  
Monsoon Rainfall ◽  
Negative Trend ◽  
Change Point Detection ◽  
Seasonal Rainfall ◽  
Annual Rainfall ◽  
Positive Trend ◽  
Northeast Monsoon ◽  
Significant Positive Trend ◽  
Significant Negative Trend ◽  
Northeast Monsoon Rainfall

The significance of the trends was tested by Mann-Kendall test for annual and seasonal rainfall. Among the 14 taluks, only Hassan taluk shows a significant positive trend in annual rainfall while eight taluks have shown non-significant positive trend and remaining five taluks have shown non-significant negative trend. The annual rainfall for the entire zone have shown non-significant positive trend. For the SWM season, Alur taluk shows a significant negative trend and eight taluks have shown non-significant positive trend. However, five taluks and whole zone showed a non-significant negative trend. Southwest monsoon and annual rainfall in Bhadravathi taluk was increased in 2007 (571.9 mm to 785.1 mm and 857.6 mm to 1090.9 mm, respectively) and in Shivamogga, the change in annual rainfall was decreased during 1983 (1497.5 mm to 944.0 mm) and 2011 (944.0 mm to 796.6 mm). The northeast monsoon rainfall was increased during 1992 (134.3 mm to 441.1 mm) and it was decreased during 1994 (441.1 mm to 162.0 mm) in Shikaripura taluk. Similarly, in Hunsur taluk, the SW Monsoon rainfall has increased (701.8 mm to 1010.2 mm) during 1991 and it was decreased during 2001 (1010.2 mm to 723.3 mm), in Periyapatna and Honnali taluk, Northeast monsoon rainfall has decreased during 2012 and 2011, respectively.

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