An observational evidence of climate change during global warming era

Naidu, C. V.; Durgalakshmi, K.; Satyanarayana, G.; Rao, L M; Ramakrishna, S. S. V. S.; Mohan, Jaddu Rama; Ratna, K. Naga

doi:10.1016/j.gloplacha.2011.07.010

Cited by 11 publications

(5 citation statements)

References 40 publications

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“…Previous studies on trends in monsoon circulation have suggested that monsoon variability has been higher over the last few decades (Dash et al ., ; Vinnarasi and Dhanya, ). These circulation changes have been directly observed in alterations in rainfall over the Indian region (Guhathakurta and Rajeevan, ; Naidu et al ., ; Krishnan et al ., ) and also in the form of sudden increases in the occurrence of extreme rainfall and flood events (Goswami et al ., ; Pattanaik and Rajeevan, ; Krishnan et al ., ). Guhathakurta et al .…”

Section: Resultsmentioning

confidence: 99%

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Variability of monsoon low‐level jet and associated rainfall over India

Viswanadhapalli

Dasari

Dwivedi

et al. 2019

Intl Journal of Climatology

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The structure and climatology of the monsoon low‐level jet (MLLJ) is studied based on dynamically downscaled simulations over a 37‐year period (1980–2016) using the Weather Research Forecasting (WRF) model. The simulations are conducted by adopting a continuous initialization method with daily re‐initializations using ERA‐Interim data as initial and boundary conditions. Validation of the downscaled fields with radiosonde data shows that the model has reasonable skill in reproducing MLLJ characteristics. Analysis of the simulations suggests that the MLLJ exhibits systematic diurnal variation: maximum winds of the synoptically induced large‐scale monsoon jet occur during the daytime, and the orographic channelled winds through the mountains of East Africa, Hejaz, and Western Ghats in the night‐time. These diurnal changes in monsoon winds modulate the moisture convergence process and the associated evolution of rainfall over India. Seasonal and monthly climatology of monsoon winds shows that the model accurately reproduces the spatial pattern of winds and slightly overestimates (2–3 m/s) the mean monthly winds over the Bay of Bengal and Arabian Seas. Analysis of wind variability and the trends using 37 years simulations suggests that the MLLJ exhibits an increasing trend in wind speed on both seasonal and monthly scales, except for August which shows a decreasing trend. The weakening of the MLLJ in August has a profound influence on the number of monsoon depressions forming over the Bay of Bengal (which are decreasing), and on the number of break days (which are increasing) and associated precipitation reduction over the central Indian region.

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Section: Resultsmentioning

confidence: 99%

“…Naidu et al . () indicated that the weakening of the zonal wind shear over the BOB (5°–22°N and 80°–100°E) between 850 and 100 hPa can lead to a decrease in the frequency of depression and cyclonic systems over the BOB and an associated decrease in the amount of rainfall during monsoon season.…”

Section: Resultsmentioning

confidence: 99%

Variability of monsoon low‐level jet and associated rainfall over India

Viswanadhapalli

Dasari

Dwivedi

et al. 2019

Intl Journal of Climatology

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“…In the consequent study, Naidu et al (2011b) observed that a significant reduction in the frequency of summer monsoon cyclonic systems over the Bay of Bengal in the global warming era is associated with a significant increase of North Atlantic Oscillation Index [NAOI], relaxation of Southern Oscillation Index [SOI] and a weak vertical zonal wind shear in the domain 5°N-22°N and 80°E-100°E. According to Srinivasa Rao et al (2004), the NCEP/NCAR reanalysis data during the period, 1958-1998 show a positive trend in the 100 hPa zonal wind i.e., a decrease in the strength of the tropical easterly jet during the summer monsoon period.…”

Section: Introductionmentioning

confidence: 94%

An observational evidence of decrease in Indian summer monsoon rainfall in the recent three decades of global warming era

Naidu

Raju

Satyanarayana

et al. 2015

Global and Planetary Change

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“…The reduction of ISM rainfall in the last 30 years in the Indian subcontinent has been attributed to weakening of the summer monsoon (SWM). This is attributed to weakening of the tropical meridional overturning circulation induced by warming of the North Indian Ocean, development of the Asian Brown Cloud, and warming over the Pacific warm pool (Annamalai et al 2013) and weakening of the tropical easterly jet (Naidu et al 2011). Warming of the Bay of Bengal and Arabian Sea has also reduced the cyclonic activity during the summer monsoon season (Naidu et al 2011).…”

Section: Seasonal Trendsmentioning

confidence: 99%

“…Although SWM is only bringing a significant rainfall to the small Wet Zone of Sri Lanka, its contribution to the irrigation systems in the Dry Zone as well as power generation is considerable. It is therefore important that we understand the recent rainfall trends in various parts of Sri Lanka in what Naidu et al (2011) described as global warming (GW) period. This study covers a 30-year period from 1981 to 2010 (GW period) and includes 48 rainfall measuring stations distributed all over the country.…”

Section: Introductionmentioning

confidence: 99%

Spatial and temporal variation of rainfall trends of Sri Lanka

Wickramagamage

2015

Theor Appl Climatol

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This study was based on daily rainfall data of 48 stations distributed over the entire island covering a 30-year period from 1981 to 2010. Data analysis was done to identify the spatial pattern of rainfall trends. The methods employed in data analysis are linear regression and interpolation by Universal Kriging and Radial Basis function. The slope of linear regression curves of 48 stations was used in interpolation. The regression coefficients show spatially and seasonally variable positive and negative trends of annual and seasonal rainfall. About half of the mean annual pentad series show negative trends, while the rest shows positive trends. By contrast, the rainfall trends of the Southwest Monsoon (SWM) season are predominantly negative throughout the country. The first phase of the Northeast Monsoon (NEM1) displays downward trends everywhere, with the exception of the Southeastern coastal area. The strongest negative trends were found in the Northeast and in the Central Highlands. The second phase (NEM2) is mostly positive, except in the Northeast. The Inter-Monsoon (IM) periods have predominantly upward trends almost everywhere, but still the trends in some parts of the Highlands and Northeast are negative. The long-term data at Watawala Nuwara Eliya and Sandringham show a consistent decline in the rainfall over the last 100 years, particularly during the SWM. There seems to be a faster decline in the rainfall in the last 3 decades. These trends are consistent with the observations in India. It is generally accepted that there has been changes in the circulation pattern. Weakening of the SWM circulation parameters caused by global warming appears to be the main causes of recent changes. Effect of the Asian Brown Cloud may also play a role in these changes.

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An observational evidence of climate change during global warming era

Cited by 11 publications

References 40 publications

Variability of monsoon low‐level jet and associated rainfall over India

Variability of monsoon low‐level jet and associated rainfall over India

An observational evidence of decrease in Indian summer monsoon rainfall in the recent three decades of global warming era

Spatial and temporal variation of rainfall trends of Sri Lanka

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