scholarly journals Long term trends in the frequency of monsoonal cyclonic disturbances over the north Indian Ocean

MAUSAM ◽  
2022 ◽  
Vol 52 (4) ◽  
pp. 655-658
Author(s):  
O. P. SINGH
Keyword(s):  
Arabian Sea ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
North Indian Ocean ◽  
The North ◽  
Long Term Trends ◽  
Cyclonic Disturbances ◽  
Southwest Monsoon Season ◽  
Cyclonic Storms

Long term trends in the frequencies of cyclonic disturbances (i.e. depressions and cyclonic storms) and the cyclonic storms forming over the Bay of Bengal and the Arabian Sea during the southwest monsoon season (June-September) have been studied utilizing 110 years data from 1890-1999. There have been significant decreasing trends in both the frequencies but the frequency of cyclonic disturbances has diminished at a faster rate. The trend analysis shows that the frequency of cyclonic disturbances has decreased at the rate of about six to seven disturbances per hundred years in the monsoon season. The frequency of cyclonic storms of monsoon season .has decreased at the rate of , one to two cyclones per hundred years.

scholarly journals Cyclonic storms and Depressions over the north Indian Ocean during 2019*

MAUSAM ◽  
2021 ◽  
Vol 71 (3) ◽  
pp. 357-376
Author(s):  
Kashyapi A ◽  
Shripad V K ◽  
Natu J C
Keyword(s):  
Arabian Sea ◽  
Monsoon Season ◽  
North Indian Ocean ◽  
Cyclonic Storm ◽  
Post Monsoon ◽  
The North ◽  
Post Monsoon Season ◽  
Severe Cyclonic Storm ◽  
Cyclonic Storms ◽  
Indian Seas

During 2019, in all 12 intense low pressure systems formed over the Indian Seas. These include; one Super cyclonic storm (KYARR), one extremely severe cyclonic storm (FANI), 4 very Severe Cyclonic Storms (VAYU, HIKAA, MAHA & BULBUL), 2 Cyclonic Storms (PABUK & PAWAN), 3 Deep Depressions and  1 Depression. Out of these 12 systems, 4 systems formed over the Bay of Bengal and 8 over the Arabian Sea. Arabian Sea remained exceptionally active in terms of cyclogenesis this year, especially in the post monsoon season. The season-wise distribution had been one cyclonic storm in winter, one in pre-monsoon season,  2 depressions and 2 very severe cyclonic storms during the monsoon season and 4 cyclonic storms and 3 depressions in Post monsoon season.

scholarly journals Occurrence of dry and wet weeks over Maharashtra

MAUSAM ◽  
2021 ◽  
Vol 51 (1) ◽  
pp. 25-38
Author(s):  
P. G. GORE ◽  
V. THAPLIYAL
Keyword(s):  
High Probability ◽  
Markov Chain Model ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Southwest Monsoon ◽  
The State ◽  
Chain Model ◽  
Temporal And Spatial Distribution ◽  
The North ◽  
Southwest Monsoon Season

Based on the daily rainfall data of the past 90 years (1901-90), the initial and conditional probabilities of a wet week and the probabilities of 2 and 3 consecutive wet weeks have been computed for all the districts of Maharashtra during the southwest monsoon season by using Markov Chain model. A temporal and spatial distribution of probabilities of wet weeks have been studied in detail. Most of the districts show the highest probability of wet weeks during July. A few number of the districts show the second highest probability during August. The western and northeastern parts of the state show 10-16 wet weeks with high probability. The high rainfall districts along the west coast show high wet week probabilities during most of the period of the season. A few number of the districts from moderate rainfall zone, show high probability of a wet week during, July and August. A persistency in rainfall is noticed in only extreme western parts of the state. The east-west variation along 19° N shows 'L' shaped pattern for the high probability wet weeks. While, the north -south variation of the wet weeks with high probability shows a sinusoidal curve from north to south.

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 On some aspects of southwest monsoon rainfall over Tamilnadu

MAUSAM ◽  
2022 ◽  
Vol 46 (4) ◽  
pp. 377-382
Author(s):  
S. K. SUBRAMANIAN ◽  
V. N. THANKAPPAN
Keyword(s):  
Monsoon Rainfall ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Point Of View ◽  
Annual Rainfall ◽  
Northeast Monsoon ◽  
The North ◽  
Rainfall Occurrence ◽  
Southwest Monsoon Rainfall ◽  
Southwest Monsoon Season

The rainfall during southwest monsoon season over Tamilnadu is quite significant from the point of view of water storage in major reservoirs as northeast monsoon rainfall, which is about half of the annual rainfall, is not stable enough due to its large interannual variability. The southwest monsoon rainfall, on the other hand, is more stable. The north-south oriented trough over Tamilnadu and adjoining Bay togetherwith upper air cyclonic circulation/trough in lower tropospheric levels account for three fourths of significant rainfall occurrence during southwest monsoon season. Rainfall during southwest monsoon and northeast monsoon seasons was found to be independent with a small negative correlation of -0.18. This shows that the southwest monsoon rainfall may not be of much use to predict the pattern of northeast monoon rainfall over Tamilnadu.  

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.

scholarly journals Oceanography of the Arabian Sea during the southwest monsoon season Part II: Stratification and circulation

MAUSAM ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 23-32
Author(s):  
J. S. SASTRY ◽  
R. S. D'SOUZA
Keyword(s):  
Spatial Distribution ◽  
Arabian Sea ◽  
Monsoon Season ◽  
Basic Feature ◽  
Southwest Monsoon ◽  
Rational Basis ◽  
Current Field ◽  
Southwest Coast Of India ◽  
Circulation Patterns ◽  
Southwest Monsoon Season

The distribution of mass in the Arabian Sea during the southwest monsoon season, 1963 is presented through several vertical sections and spatial distribution charts of the thermosteric anomaly. The circulation patterns in the upper 200 m are derived. The basic feature of circulation is found to be the formation of several cyclonic and anti-cyclonic cells. Upwelling off the southwest coast of India has been explained on a more rational basis than has been assumed hitherto. It is now attributed partly due to the divergence in the current field and partly due to the cyclonic motion around Laccadive and Maldive Island.

scholarly journals Long term trends in the sea surface temperature of the Black Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 491-501 ◽  
Author(s):  
G. I. Shapiro ◽  
D. L. Aleynik ◽  
L. D. Mee
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
The North ◽  
Sst Variability ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

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