scholarly journals Sub-division wise probabilistic variability and extreme rainfall analysis of the Indian summer monsoon rainfall

MAUSAM ◽  
2021 ◽  
Vol 49 (2) ◽  
pp. 235-246
Author(s):  
N. C. BISWAS ◽  
S. N. DUTTA
Keyword(s):  
Monsoon Rainfall ◽  
Extreme Values ◽  
Extreme Rainfall ◽  
Summer Monsoon Rainfall ◽  
Monsoon Period ◽  
Rainfall Analysis ◽  
The North ◽  
Efficient Management ◽  
Past Data ◽  
Time Basis

Statistical analysis based on past data on probability of normal/excess rainfall, the probable future rainfall for smaller areas at different stages of the monsoon period will serve as an appropriate information system for efficient management of available surface water resource at the state and the national levels. In this paper the author have made an attempt in that direction and have brought out some important features of the monsoon rainfall. It is found that the probability of monthly rainfall becoming normal or excess is high in maximum number of sub-divisions in July and August and is least in September. It is further observed that the normality of rainfall as highly probable to the north of the monsoon trough in July and that to the south of the trough in August besides the west coast. The rainfall extreme values over a long period will be useful in determining the minimum assured and maximum probable future rainfall at different stages of the monsoon period. These information will be valuable to decision makers, managers etc. in their decision making process on real time basis.  

scholarly journals Comparison of TMPA-3B42 Versions 6 and 7 Precipitation Products with Gauge-Based Data over India for the Southwest Monsoon Period

2015 ◽  
Vol 16 (1) ◽  
pp. 346-362 ◽  
Author(s):  
Satya Prakash ◽  
Ashis K. Mitra ◽  
Imranali M. Momin ◽  
D. S. Pai ◽  
E. N. Rajagopal ◽  
...  
Keyword(s):  
Monsoon Rainfall ◽  
Central India ◽  
Tropical Rainfall Measuring Mission ◽  
Southwest Monsoon ◽  
Summer Monsoon Rainfall ◽  
Monsoon Period ◽  
Light Rain ◽  
Rainfall Frequency ◽  
India Summer Monsoon ◽  
Marginal Improvement

Abstract The upgraded version 7 (V7) of the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) products is available to the user community. In this paper, two successive versions of the TMPA-3B42 research monitoring product, version 6 (V6) and V7, at the daily scale are evaluated over India during the southwest monsoon with gauge-based data for a 13-yr (1998–2010) period. Over typical monsoon rainfall zones, biases are improved by 5%–10% in V7 over the regions of higher rainfall like the west coast, northeastern, and central India. A similar reduced bias is seen in V7 over the rain-shadow region located in southeastern India. In terms of correlation, anomaly correlation, and RMSE, a marginal improvement is seen in V7. Additionally, in all-India summer monsoon rainfall amounts, mean, interannual values, and standard deviation show an overall improvement in V7. Different skill metrics over typical subregions within India show an improvement of the monsoon rainfall representation in V7. Rainfall frequency in different categories also indicates an overall improvement in V7 across all scales and subregions. Over central India regions associated with the monsoon transients, the sign of the bias has changed toward a positive bias. Even if the bias in the frequency of the occurrence of light rain has improved in V7, the values still show a large difference compared to observations. Though both V6 and V7 are able to represent the anomalous dry/wet regions during contrasting monsoon years, V7 shows some improvement in amplitude of those anomalies over V6. In general, V7 has considerably improved over V6 and will continue to be in demand from various sectors of observed rainfall data users.

Seasonal Shifts in the North American Monsoon

2007 ◽  
Vol 20 (9) ◽  
pp. 1923-1935 ◽  
Author(s):  
Katrina Grantz ◽  
Balaji Rajagopalan ◽  
Martyn Clark ◽  
Edith Zagona
Keyword(s):  
United States ◽  
North American ◽  
Gulf Of California ◽  
Monsoon Rainfall ◽  
Monsoon Season ◽  
North American Monsoon ◽  
Southwestern United States ◽  
Monsoon Period ◽  
The North ◽  
Ocean Conditions

Abstract Analysis is performed on the spatiotemporal attributes of North American monsoon system (NAMS) rainfall in the southwestern United States. Trends in the timing and amount of monsoon rainfall for the period 1948–2004 are examined. The timing of the monsoon cycle is tracked by identifying the Julian day when the 10th, 25th, 50th, 75th, and 90th percentiles of the seasonal rainfall total have accumulated. Trends are assessed using the robust Spearman rank correlation analysis and the Kendall–Theil slope estimator. Principal component analysis is used to extract the dominant spatial patterns and these are correlated with antecedent land–ocean–atmosphere variables. Results show a significant delay in the beginning, peak, and closing stages of the monsoon in recent decades. The results also show a decrease in rainfall during July and a corresponding increase in rainfall during August and September. Relating these attributes of the summer rainfall to antecedent winter–spring land and ocean conditions leads to the proposal of the following hypothesis: warmer tropical Pacific sea surface temperatures (SSTs) and cooler northern Pacific SSTs in the antecedent winter–spring leads to wetter than normal conditions over the desert Southwest (and drier than normal conditions over the Pacific Northwest). This enhanced antecedent wetness delays the seasonal heating of the North American continent that is necessary to establish the monsoonal land–ocean temperature gradient. The delay in seasonal warming in turn delays the monsoon initiation, thus reducing rainfall during the typical early monsoon period (July) and increasing rainfall during the later months of the monsoon season (August and September). While the rainfall during the early monsoon appears to be most modulated by antecedent winter–spring Pacific SST patterns, the rainfall in the later part of the monsoon seems to be driven largely by the near-term SST conditions surrounding the monsoon region along the coast of California and the Gulf of California. The role of antecedent land and ocean conditions in modulating the following summer monsoon appears to be quite significant. This enhances the prospects for long-lead forecasts of monsoon rainfall over the southwestern United States, which could have significant implications for water resources planning and management in this water-scarce region.

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.

scholarly journals Interdecadal Variability in Myanmar Rainfall in the Monsoon Season (May–October) Using Eigen Methods

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 729
Author(s):  
Zin Mie Mie Sein ◽  
Irfan Ullah ◽  
Farhan Saleem ◽  
Xiefei Zhi ◽  
Sidra Syed ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
Monsoon Rainfall ◽  
North Atlantic Ocean ◽  
Summer Monsoon Rainfall ◽  
Interdecadal Variability ◽  
The North ◽  
Eastern Equatorial Pacific ◽  
Rainfall Anomalies ◽  
The North Atlantic

In this study, we investigated the interdecadal variability in monsoon rainfall in the Myanmar region. The gauge-based gridded rainfall dataset of the Global Precipitation Climatology Centre (GPCC) and Climatic Research Unit version TS4.0 (CRU TS4.0) were used (1950–2019) to investigate the interdecadal variability in summer monsoon rainfall using empirical orthogonal function (EOF), singular value decomposition (SVD), and correlation approaches. The results reveal relatively negative rainfall anomalies during the 1980s, 1990s, and 2000s, whereas strong positive rainfall anomalies were identified for the 1970s and 2010s. The dominant spatial variability mode showed a dipole pattern with a total variance of 47%. The power spectra of the principal component (PC) from EOF revealed a significant peak during decadal timescales (20–30 years). The Myanmar summer monsoon rainfall positively correlated with Atlantic multidecadal oscillation (AMO) and negatively correlated with Pacific decadal oscillation (PDO). The results reveal that extreme monsoon rainfall (flood) events occurred during the negative phase of the PDO and below-average rainfall (drought) occurred during the positive phase of the PDO. The cold phase (warm phase) of AMO was generally associated with negative (positive) decadal monsoon rainfall. The first SVD mode indicated the Myanmar rainfall pattern associated with the cold and warm phase of the PDO and AMO, suggesting that enhanced rainfall for about 53% of the square covariance fraction was related to heavy rain over the study region except for the central and eastern parts. The second SVD mode demonstrated warm sea surface temperature (SST) in the eastern equatorial Pacific (El Niño pattern) and cold SST in the North Atlantic Ocean, implying a rainfall deficit of about 33% of the square covariance fraction, which could be associated with dry El Niño conditions (drought). The third SVD revealed that cold SSTs in the central and eastern equatorial Pacific (La Niña pattern) caused enhance rainfall with a 6.7% square covariance fraction related to flood conditions. Thus, the extra-subtropical phenomena may affect the average summer monsoon trends over Myanmar by enhancing the cross-equatorial moisture trajectories into the North Atlantic Ocean.

scholarly journals An oceanic model for the prediction of southwest monsoon rainfall over India

MAUSAM ◽  
2021 ◽  
Vol 47 (1) ◽  
pp. 91-98
Author(s):  
J. P. SlNGH ◽  
D. S. PAI
Keyword(s):  
Indian Ocean ◽  
Regression Model ◽  
Summer Monsoon ◽  
Arabian Sea ◽  
Monsoon Rainfall ◽  
Principal Component ◽  
Southwest Monsoon ◽  
Summer Monsoon Rainfall ◽  
North Indian Ocean ◽  
The North

Nine new oceanic predictor for long range forecasting of Indian summer monsoon rainfall been identified utilizing  the marine meteorological data of the North Indian Ocean and the monsoon rainfall data of the period 1961-91. In order to develop a reliable regression model the principal component analysis (PCA) of original variables has been done. Five parameters having maximum influence on first principal component, which is having highest correlation with the monsoon rainfall are : wind power in the atmospheric boundary layer over the north Indian Ocean between Equator and 100 N, mean evaporation over the Arabian Sea (00 -150 N) mean sea surface temperature (SST) gradient over the Arabian Sea between 7.50 – 17.50 N, mean evaporation over Bay of Bengal between Equator and 100 N and mean sea level pressure (SLP) over the Arabian Sea, each pertaining to the month of May. A multiple regression model for all Indian rainfall of southwest monsoon season has been developed using the principal components which have got good cor-relations with the monsoon rainfall. The model was tested for all the years from 1987 to 1991 and it has been found that the predicted values of all India summer monsoon rainfall of all the years except 1989 were very close to the actual values. However, there was a substantial difference between the predicted and actual rainfall of 1989 summer monsoon.

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