scholarly journals EMPIRICAL ORTHOGONAL FUNCTIONS ASSOCIATED WITH PARAMETERS USED IN LONG RANGE FORECASTING OF INDIAN SUMMER MONSOON

MAUSAM ◽  
2021 ◽  
Vol 44 (1) ◽  
pp. 29-34
Author(s):  
H. N. SRIVASTAVA ◽  
S. S. SINGH
Keyword(s):  
Snow Cover ◽  
Long Range ◽  
Northern Hemisphere ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Monsoon Onset ◽  
Empirical Orthogonal Functions ◽  
Onset Date ◽  
Orthogonal Functions ◽  
Summer Monsoon Onset

EEmpirical Orthogonal Functions (EOF),. associated with the; parameters for long range forecasting of Indian summer monsoon onset and seasonal. rainfall have been discussed. It was found that the percentage of variance explained was 77 and 67 respectively through the first four EOF. The highest correlation coefficient with the onset date was found for the first function which showed the maximum influence of Cobar (Australia) and Darwin (Australia) zonal winds on the onset date. It was interesting to note that for rainfall prediction predominant effect on the first EOF was noticed of 50 hPa ridge over northern hemisphere, Eurasian snow cover, Argentina pressure (negatively correlated) and 500 hpa ridge, 10 hPa Balboa wind, north, central India and east coast  minimum temperatures, and northern hemisphere temperature. However, the Influence of EI-Nino, equatorial pressure and Darwin pressure (Including Tahiti minus Darwin) and Himalayan snow cover was almost negligible. The eigen index for the onset date suggests a complementary method for its application In long range prediction of summer monsoon onset date.

scholarly journals Tracking the Indian Summer Monsoon Onset Back to the Preinstrument Period

2016 ◽  
Vol 29 (22) ◽  
pp. 8115-8127 ◽  
Author(s):  
Paulina Ordoñez ◽  
David Gallego ◽  
Pedro Ribera ◽  
Cristina Peña-Ortiz ◽  
Ricardo García-Herrera
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
India Meteorological Department ◽  
Monsoon Onset ◽  
Onset Date ◽  
Late Nineteenth Century ◽  
Stable Relationship ◽  
Summer Monsoon Onset ◽  
The Pacific ◽  
Precipitation Increase

Abstract The Indian summer monsoon onset is one of the most expected meteorological events of the world, affecting the lives of hundreds of millions of people. The India Meteorological Department has dated the monsoon onset since 1901, but its original methodology was considered subjective and it was updated in 2006. Unfortunately, the new method relies on OLR measurements, which impedes the construction of an objective onset series before the 1970s. An alternative approach is the use of the wind field, but the development of such an index is limited to the period covered by reanalysis products. In this paper historical wind records taken on board ships are used to develop a new onset series using only wind direction measurements, providing an objective record of the onset since the late nineteenth century. The new series captures the rapid precipitation increase associated with the onset, correlates well with previous approaches, and is robust against anomalous (bogus) onsets. A tendency for later-than-average onsets during the 1900–25 and 1970–90 periods and earlier-than-average onsets between 1940 and 1965 was found. A relatively stable relationship between ENSO and Indian monsoon onset dates was found; however, this link tends to be weaker during decades characterized by prevalent La Niña conditions. Furthermore, it was found that the link between the Pacific decadal oscillation (PDO) and the onset date is limited to the phases characterized by a shift from negative to positive PDO phases.

scholarly journals Oceanic factors controlling the Indian summer monsoon onset in a coupled model

2014 ◽  
Vol 44 (3-4) ◽  
pp. 977-1002 ◽  
Author(s):  
Chloé Prodhomme ◽  
Pascal Terray ◽  
Sébastien Masson ◽  
Ghyslaine Boschat ◽  
Takeshi Izumo
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Coupled Model ◽  
Monsoon Onset ◽  
Summer Monsoon Onset

scholarly journals Relationship between monsoon onset over Thiruvananthapuram and Mumbai and rainfall over Kerala and Konkan

MAUSAM ◽  
2021 ◽  
Vol 57 (3) ◽  
pp. 445-450
Author(s):  
M. P. SHEWALE ◽  
A. S. PONKSHE
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Significant Relationship ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Summer Monsoon Rainfall ◽  
Monsoon Onset ◽  
Onset Date ◽  
Simultaneous Occurrence

Lkkj & bl ’kks/k&Ik= esa nks LFkkuksa uker% fFk:ouUriqje vkSj eqEcbZ dk p;u djds ;g irk yxkus dk iz;kl fd;k x;k gS fd D;k ekulwu ds vkxeu dh rkjh[k dk Øze’k% dsjy vkSj dksad.k esa gksus okyh o"kkZ ds lkFk dksbZ laca/k gS A lewps ns’k ds fy, Hkkjrh; xzh"edkyhu ekulwu o"kkZ ¼vkbZ- ,l- ,e- vkj-½ ds lkFk ekulwu ds vkxeu dh rkjh[k ds laca/k dh Hkh tk¡p dh xbZ gS A bl v/;;u ds fy, 100 o"kksaZ ¼1901&2000½ ds vk¡dM+ksa dk mi;ksx fd;k x;k gS A             fo’ys"k.k dh lgk;rk ls vk¡dM+ksa dh ,d:irk vkSj o"kkZ ds vU; y{k.kksa dh tk¡p dh xbZ gS A dsjy vkSj dksad.k esa vdky vkSj ekSle laca/kh ck<+ dh ledkfyd ?kVukvksa dh vko`fr dk irk yxk;k x;k gS vkSj mldh tk¡p dh xbZ gS A             bl v/;;u ls ;g irk pyk gS fd ekulwu ds vkxeu ds laca/k esa fFk:ouUriqje vkSj eqEcbZ ds chp egRoiw.kZ laca/k gS A fFk:ouariqje vFkok eqEcbZ vkSj vkbZ- ,l- ,u- vkj- ds chp ekulwu ds vkxeu ds ckjs esa fdlh egRoiw.kZ laca/k dk irk ugha pyk gS A dsjy dh rqyuk eas dksad.k esa ekSle laca/kh ck<+ vf/kd vkrh gS A In this paper, choosing two locations viz., Thiruvananthapuram and Mumbai, an attempt has been made to find whether the onset date of monsoon has any bearing on monsoon rainfall over Kerala and Konkan respectively.   Association of the onset dates with Indian Summer Monsoon Rainfall (ISMR) for the country as a whole has also been explored.  The study utilizes 100 years’ (1901-2000) data. Homogeneity of the data and other rainfall features have been examined with the help of  analysis.  Frequency of simultaneous occurrence of droughts and meteorological floods at Kerala and Konkan have been determined and examined.    The study showed that onset over Thiruvananthapuram and Mumbai are significantly related.  It revealed absence of any significant relationship between onset over Thiruvananthapuram or Mumbai and the ISMR. Meteorological floods seem to be more frequent over Konkan compared to Kerala.

scholarly journals Decadal-Scale Variation of South Asian Summer Monsoon Onset and Its Relationship with the Pacific Decadal Oscillation

2014 ◽  
Vol 27 (13) ◽  
pp. 5163-5173 ◽  
Author(s):  
Takeshi Watanabe ◽  
Koji Yamazaki
Keyword(s):  
Pacific Ocean ◽  
Summer Monsoon ◽  
Pacific Decadal Oscillation ◽  
Wave Train ◽  
Monsoon Onset ◽  
Onset Date ◽  
South Asian Summer Monsoon ◽  
Summer Monsoon Onset ◽  
Decadal Scale ◽  
Northern Pacific

The variation of the summer monsoon onset over South Asia was investigated by using long-term data of the onset over Kerala, India, during the 64-yr period from 1948 to 2011. It was found that the onset over Kerala shows variation on a multidecadal scale. In early-onset years, the sea surface temperature (SST) anomaly over the northern Pacific Ocean was very similar to the negative Pacific decadal oscillation (PDO). The stationary wave train related to the negative PDO reaches into central Asia and generates a warm anomaly, thereby intensifying the land–sea thermal contrast, which promotes summer monsoon onset over South and Southeast Asia. The correlation between the onset date over Kerala and the PDO has strengthened since 1976. Analysis of zonal wind in the upper-level troposphere for the period 1958–2002 indicates that the change in the correlation is related to the change in the wave train path. The wave train propagating from the northern Pacific Ocean to western Russia could propagate eastward more easily in 1976–2002 than in 1958–75.

scholarly journals Long-range prediction of monsoon onset over Kerala

MAUSAM ◽  
2022 ◽  
Vol 46 (3) ◽  
pp. 287-290
Author(s):  
M. RAJEEVAN ◽  
D. P. DUBEY
Keyword(s):  
Surface Temperature ◽  
Snow Cover ◽  
Long Range ◽  
Late Onset ◽  
Central India ◽  
Monsoon Onset ◽  
Onset Date ◽  
Eurasian Snow Cover ◽  
Eurasian Snow ◽  
Long Range Prediction

ABSTRACT. Using the data of 33 years ( 1961-1993) the effect of the intensity of heat low over central India during the Month of April and Winter (December to February) Eurasian snow cover on interannual variation of monsoon date over Kerala were examined. Composite mean surface temperature over central India during the month of April was higher during early onset years by 3.5° C. April mean surface temperature index (MST) and Winter (December to February) Eurasian snow cover (WSC) are significantly correlated with Monsoon onset dates al 1% and 5% significant levels respectively. Lower surface temperature and excessive snow cover indicate a late onset. A regression equation was developed for long range prediction of onset date over Kerala using MST and WSC as independent variables. The root mean square error (RMSE) of the relationship was found to be 4.6 days. The model was tested using independent data of five years and was found performing well. Contingency tables were developed between the pairs MOD and WSC and MOD and MST. The tables can be used for probability forecasts of early and late onset years.  

scholarly journals Progress of Indian summer monsoon onset and convective episodes over Indo-Pacific region observed during 2009-2014

MAUSAM ◽  
2021 ◽  
Vol 67 (4) ◽  
pp. 803-828
Author(s):  
S. P. GHANEKAR ◽  
S. G. NARKHEDKAR ◽  
D. R. SIKKA
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
North Indian Ocean ◽  
Monsoon Onset ◽  
Andaman Sea ◽  
Case Review ◽  
Weather Information ◽  
Summer Monsoon Onset ◽  
Oceanic Region ◽  
Time Required

 Summer monsoon onset progress from the oceanic region of Southeast Bay of Bengal / Andaman Sea (Oceanr) up to extreme southwestern part of India (Kerala) for the years 2009 to 2014 is investigated. Synoptic weather information, INSAT/KALPANA-1 as well as cloud imageries archived from Dundee Satellite Receiving Station for May and early June for these years are used in the analysis. Upper-air reanalyzed winds from NCEP/NCAR and OLR data archived through NOAA satellites are also used. During the study period, the dates of monsoon onset as well as the time required for the advancement of onset from Oceanr to Kerala have shown a large variation. An attempt is made to investigate the causes for such variations. The results indicate that intense disturbances which formed over north Indian Ocean in 2009, 2010, 2013 and 2014 and over west-north Pacific Oceanic region in 2011 and 2012 have contributed for the same. Analysis is carried out, limiting its focus to bring out the role of these convective events in the observed variation of onset timing and its progress by taking case to case review of these events and bringing out their influence through synoptic analysis. Utility of this information in prediction of the progress of Indian summer monsoon onset is also brought out.  

Seasonal prediction of Indian Summer Monsoon onset with machine learning

2021 ◽  
Author(s):  
Takahito Mitsui ◽  
Niklas Boers
Keyword(s):  
Time Scales ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Water Resource Management ◽  
Prediction Models ◽  
Indian Subcontinent ◽  
Weather Prediction ◽  
Seasonal Prediction ◽  
Onset Date ◽  
Summer Monsoon Onset

&lt;p&gt;The prediction of the onset date of the Indian Summer Monsoon (ISM) is crucial for effective agricultural planning and water resource management on the Indian subcontinent, with more than one billion inhabitants. Existing approaches focus on extended-range to subseasonal forecasts, i.e., provide skillful predictions of the ISM onset date at horizons of 10 to 60 days. Here we propose a method for ISM onset prediction and show that it has high forecast skill at longer, seasonal time scales. The method is based on recurrent neural networks and allows for ensemble forecasts to quantify uncertainties. Our approach outperforms state-of-the-art numerical weather prediction models at comparable or longer lead times. To our knowledge, there is no statistical forecasting approach at comparable, seasonal time scales. Our results suggest that predictability of the ISM onset emerges earlier than previously assumed.&lt;/p&gt;

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