Relationship between northeast monsoon rainfall and near-surface atmospheric wind convergence over the North Indian Ocean using multisatellite data

2013 ◽  
Vol 68 (2) ◽  
pp. 763-774 ◽  
Author(s):  
Satya Prakash ◽  
R. M. Gairola
Keyword(s):  
Indian Ocean ◽  
Monsoon Rainfall ◽  
North Indian Ocean ◽  
Northeast Monsoon ◽  
Near Surface ◽  
The North ◽  
Northeast Monsoon Rainfall

scholarly journals Statistical prediction of seasonal cyclonic activity over North Indian Ocean

MAUSAM ◽  
2021 ◽  
Vol 63 (1) ◽  
pp. 17-28
Author(s):  
S. BALACHANDRAN ◽  
B. GEETHA
Keyword(s):  
Indian Ocean ◽  
Regression Model ◽  
North Indian Ocean ◽  
Statistical Prediction ◽  
Quantitative Prediction ◽  
Climate Indices ◽  
Bias Error ◽  
Northeast Monsoon ◽  
Cyclonic Activity ◽  
The North

The Northeast monsoon season of October to December (OND) is the primary season of cyclonic activity over the North Indian Ocean (NIO). The mean number of days of cyclonic activity over NIO during this season is about 20 days. In the present study, statistical prediction for seasonal cyclonic activity over the North Indian Ocean during the cyclone season of October to December is attempted using well known climate indices and regional circulation features during the recent 30 years of 1971-2000.Potential predictors are identified using correlation analysis and optimum numbers of predictors are chosen using screening regression technique. A qualitative prediction for number of Cyclonic Disturbance (CD) days is attempted by analysing the conditional means of the number of CD days during OND over NIO for different intervals of each predictor based on the 30 year data of 1971-2000. Predictions and their validations for the subsequent test period of 2001 to 2009, based on this scheme, are discussed. An attempt for quantitative prediction is also made by developing a multiple regression model for prediction of number of CD days over the NIO during OND using the same predictors. The regression model accounts for 70% of the inter annual variance. The root mean square error of estimate is 5 days and the bias error is 0.36 days. The regression model is cross validated by Jackknife method for each individual year using the data of 29 years from the sample excluding the year under consideration. The model is also tested for independent dataset for the years 2001 to 2009. Salient features of the model performance are discussed.

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 The effect of ENSO / Anti ENSO on northeast monsoon rainfall

MAUSAM ◽  
2021 ◽  
Vol 50 (4) ◽  
pp. 343-354
Author(s):  
U. S. DE ◽  
R. K. MUKHOPADHYAY
Keyword(s):  
Tamil Nadu ◽  
Arabian Sea ◽  
Monsoon Rainfall ◽  
Southern Oscillation ◽  
Northeast Monsoon ◽  
Monsoon Precipitation ◽  
Peninsular India ◽  
Enso Events ◽  
The North ◽  
Northeast Monsoon Rainfall

Northeast monsoon precipitation data of 5 meteorological sub-divisions in India, spanning the period 1901-97, were analysed to identify the effect of ENSO/Anti ENSO events on the rainfall over southern peninsular India. ENSO/Anti ENSO years were selected on the basis of seasonal Southern Oscillation Index (SOI). The analysis revealed that ENSO years were generally associated with enhanced northeast monsoon precipitation while there was reduced precipitation during Anti ENSO years, the reduction in Anti ENSO years being significant for Tamil Nadu (at 0.1% level), for Kerala (at 1% level) and for South Peninsular India (at 1% level). Of 22 ENSO years, 18 years were found to be either flood or wet years, while 11 years out of 15 Anti ENSO years were found to be either drought or dry years.   During ENSO years, the Sea Surface Temperature (SST) anomalies both over the Arabian Sea and the Bay of Bengal were positive during the months October to December, while the reverse was the case during Anti ENSO years. A concurrent significant positive correlation was noted between SST over east central Arabian Sea and the north central Bay regions and northeast monsoon rainfall.   The cyclonic systems were observed to form relatively at lower latitudes during ENSO years as compared to those during Anti ENSO years. These systems were also found to move in a more westerly direction, hit Tamil Nadu and south Andhra coast, thus giving more rain over peninsula during ENSO years. The ridge line at 200 hPa level during ENSO years was located 3° south as compared to its location during Anti ENSO years.

scholarly journals Principal component analysis of monthly mean Area surface temperature over the Arabian Sea, Bay of Bengal and north Indian Ocean for two Contrasting sets of monsoon years

MAUSAM ◽  
2021 ◽  
Vol 44 (1) ◽  
pp. 69-76
Author(s):  
T. K. BALAKRISHNAN ◽  
A. K. JASWAL ◽  
S.S.. SINGH ◽  
H. N. SRIVASTAVA
Keyword(s):  
Indian Ocean ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Monsoon Rainfall ◽  
Equatorial Indian Ocean ◽  
Principal Component ◽  
North Indian Ocean ◽  
Orthogonal Function ◽  
The North ◽  
Extreme North

The spatial distribution and temporal variation of the monthly mean SSTA over the Arabian Sea, Bay of Bengal and the north Indian Ocean were investigated for a set of contrasting years of monsoon over the period 1961-80 for months April through July using Empirical Orthogonal Function (EOF) technique with a view to identify regions that are significantly related to the monsoon rainfall. Over 75% of the total variance is, explained by the first mode EOF. SSTA over the north and northeast Arabian Sea during pre-monsoon months were found to be possible indicators of the ensuing monsoon activity. The higher eigen vectors in May over northeast Arabian Sea may signal good monsoon and vice versa. In June there is a marked contrast in the distribution of SST over the Arabian Sea between the two sets of the years the eastern Arabian Sea IS warmer for the deficient monsoon years while the entire Arabian Sea except over the extreme north Arabian Sea is cool during good monsoon years. There is formation of SSTA over the equatorial Indian Ocean area close to Indonesian island commencing from May which is more marked in June and is positively correlated with seasonal rainfall activity over India.  

scholarly journals The association between the north Indian Ocean and summer monsoon rainfall over India

MAUSAM ◽  
2021 ◽  
Vol 49 (3) ◽  
pp. 325-330
Author(s):  
O. P. SINGH
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Arabian Sea ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Meteorological Data ◽  
Summer Monsoon Rainfall ◽  
North Indian Ocean ◽  
The North ◽  
The Mean

Utilizing the marine meteorological data of the period 1961-81, the sea level pressure (SLP) and sea surface temperature (SST) distributions have been obtained on a 5° grid-mesh over the north Indian Ocean area bounded by  0°- 25°N, 50°- l00°E for each individual year. It has been found that the SLP and SST fields for the month of May provide predictive indications of subsequent summer monsoon rainfall over India. Significant negative correlations have been found between the mean SLPs of May over the latitudinal belts 5°-10°, 10°- 15°, 15°-20° and 20°-25°N of Arabian Sea and Bay of Bengal and all India rainfall departures of succeeding summer monsoon season. The mean SST gradient over the Arabian Sea between 7.5°- 17 .5°N during May has been found to have significant positive correlation with all India rainfall of subsequent monsoon. The study suggests that certain functions of SLP and SST of May over the north Indian Ocean can prove to be useful predictors for subsequent summer monsoon rainfall over India.

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