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.

A Moist Entropy Budget View of the South Asian Summer Monsoon Onset

2019 ◽  
Vol 46 (8) ◽  
pp. 4476-4484
Author(s):  
Ding Ma ◽  
Adam H. Sobel ◽  
Zhiming Kuang ◽  
Martin S. Singh ◽  
Ji Nie
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Monsoon Onset ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Summer Monsoon Onset ◽  
Asian Summer ◽  
Entropy Budget

scholarly journals Impact of Climate Change on the Characteristics of Indian Summer Monsoon Onset

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Savita Patwardhan ◽  
Ashwini Kulkarni ◽  
K. Krishna Kumar
Keyword(s):  
Climate Change ◽  
Summer Monsoon ◽  
Regional Climate ◽  
Monsoon Onset ◽  
Wave Radiation ◽  
Onset Date ◽  
Impact Of Climate Change ◽  
Summer Monsoon Onset ◽  
Significant Difference ◽  
The Impact

A high resolution regional climate modeling system, known as PRECIS (Providing REgional Climate for Impact Studies), developed by Hadley Centre for Climate Prediction and Research, UK, is applied for Indian subcontinent to assess the impact of climate change on the summer monsoon onset characteristics. The present day simulation (1961–1990) with PRECIS is evaluated for the characteristics of onset over Kerala, southernmost part of India, where the monsoon sets in over Indian landmass. The meteorological parameters like precipitation, outgoing long wave radiation (OLR), and low level winds are analysed to study the monsoon onset over Kerala. The model is able to capture the sudden and sharp increase of rainfall associated with the onset. The rapid built-up of convective activity over the southeastern Arabian Sea and Bay of Bengal is well represented by the model. PRECIS simulations, under scenarios of increasing greenhouse gas concentrations and sulphate aerosols, are analysed to study the likely changes in the onset characteristics in future, towards the end of present century (2071–2100). The analysis does not indicate significant difference in the mean onset dates in A2 and B2 scenarios. However, the variability of onset date is likely to be more towards the end of the 21st century especially in A2 scenario.

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 Transport of short-lived climate forcers/pollutants (SLCF/P) to the Himalayas during the South Asian summer monsoon onset

2014 ◽  
Vol 9 (8) ◽  
pp. 084005 ◽  
Author(s):  
P Cristofanelli ◽  
D Putero ◽  
B Adhikary ◽  
T C Landi ◽  
A Marinoni ◽  
...  
Keyword(s):  
South Asian ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Monsoon Onset ◽  
South Asian Summer Monsoon ◽  
The South ◽  
Summer Monsoon Onset ◽  
Asian Summer

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.

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