Seasonal Weather and its Prediction*

Walker, Gilbert T.

doi:10.1038/132805a0

Cited by 23 publications

(14 citation statements)

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“… Baines and Cai [2000] suggested that the extratropical anomalies generated by ACW, could be maintained by the interaction between ocean and atmosphere through the transfer of momentum from atmosphere to ocean and flux of heat from ocean to the atmosphere. Indian summer monsoon (June–September) is an important component of the general circulation of the atmosphere stemming its connection with a number of regional and global parameters [ Walker , 1933; Gowariker et al , 1989]. The inter‐annual variability of the Indian summer monsoon rainfall (AISMR) occasionally leads to large scale droughts or excess monsoon years.…”

Section: Introductionmentioning

confidence: 99%

Role of Antarctic circumpolar wave in modulating the extremes of Indian summer monsoon rainfall

Prabhu

Mahajan

Khaladkar

et al. 2010

Geophysical Research Letters

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[1] Sea ice extent (SIE) over different sectors of Antarctica displays intra-seasonal and inter-annual variability. It is reflected in different atmospheric and oceanic parameters, which are characterized as the manifestation of Antarctic circumpolar wave (ACW). Due to its large areal extent, ACW is linked to the global climate. Another global phenomenon, which is instrumental for the well being of vast population of the Asian sub-continent, is the Indian summer monsoon season (June-September). The quantum of all India summer monsoon rainfall (AISMR) received during the season decides the overall economic health of the country with the extremes causing disastrous situation, in either way. In the present study, the cases of the excess monsoon and drought years of the recent decades are considered to determine the possible role played by the ACW in influencing the monsoon rainfall. The correlation analyses, carried out for a period of 26 years from 1980 to 2005, show that the SIE over the Bellingshausen and Amundsen Sea Sector (BASS) during the austral summer (October-December) has an inverse relationship with the AISMR of the following year. Further, it is revealed that the sea surface temperature and the upper tropospheric meridional transport of heat over the southeast Pacific, during the period preceding the monsoon season, show contrasting behavior with respect to the extremes of AISMR. These parameters bring out the role of both the oceanic and the atmospheric modes of the ACW in modulating the AISMR. The study has a potential application in forecasting of the monsoon rainfall a few months in advance.

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Section: Introductionmentioning

confidence: 99%

Role of Antarctic circumpolar wave in modulating the extremes of Indian summer monsoon rainfall

Prabhu

Mahajan

Khaladkar

et al. 2010

Geophysical Research Letters

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“…Attempts to identify external factors controlling monsoon IAV has a long history. Following the severe drought of 1918, Sir Gilbert Walker attempted to identify several global climatic signals that are related to the Indian monsoon rainfall leading to the discovery of strong connection between the El-Niño and Southern Oscillation (ENSO) and the Indian monsoon (Walker and Bliss 1932;Walker 1933). Since then, many studies (Sikka 1980;Rasmusson and Carpenter 1982;Webster and Yang 1992;Saith and Slingo 2006) have examined in detail the association of ENSO with below normal rainfall/monsoon droughts.…”

Section: Introductionmentioning

confidence: 99%

Eastward propagating MJO during boreal summer and Indian monsoon droughts

2008

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Improved understanding of underlying mechanism responsible for Indian summer monsoon (ISM) droughts is important due to their profound socio-economic impact over the region. While some droughts are associated with 'external forcing' such as the El-Niño and Southern Oscillation (ENSO), many ISM droughts are not related to any known 'external forcing'. Here, we unravel a fundamental dynamic process responsible for droughts arising not only from external forcing but also those associated with internal dynamics. We show that most ISM droughts are associated with at least one very long break (VLB; breaks with duration of more than 10 days) and that the processes responsible for VLBs may also be the mechanism responsible for ISM droughts. Our analysis also reveals that all extended monsoon breaks (whether co-occurred with El-Niño or not) are associated with an eastward propagating Madden-Julian Oscillation (MJO) in the equatorial Indian Ocean and western Pacific extending to the dateline and westward propagating Rossby waves between 10°and 25°N. The divergent Rossby wave associated with the dry phase of equatorial convection propagates westward towards Indian land, couple with the northward propagating dry phase and leads to the sustenance of breaks. Thus, the propensity of eastward propagating MJO during boreal summer is largely the cause of monsoon droughts. While short breaks are not accompanied by westerly wind events (WWE) over equatorial western Pacific favorable for initiating air-sea interaction, all VLBs are accompanied by sustained WWE. The WWEs associated with all VLB during 1975-2005 initiate air-sea interaction on intraseasonal time scale, extend the warm pool eastward allowing the convectively coupled MJO to propagate further eastward and thereby sustaining the divergent circulation over India and the monsoon break. The ocean-atmosphere coupling on interannual time scale (such as El-Niño) can also produce VLB, but not necessary.

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“…Few studies also dealt with the characterization and forecasting of monsoon rainfall over India (Walker 1933;Shukla and Paolino 1983;Kripalani and Kulkarni 1997;Bhattcharya and Narasimha 2007). Several attempts also made to understand the connections between monsoon rainfall over Stoch Environ Res Risk Assess India and different global climatic oscillations.…”

Section: Related Workmentioning

confidence: 97%

“…Several attempts also made to understand the connections between monsoon rainfall over Stoch Environ Res Risk Assess India and different global climatic oscillations. Walker (1933) was perhaps the first to study teleconnections between Indian monsoon rainfall and meteorological parameters at other parts of the earth. Later, several other studies investigated the links of Indian monsoon rainfall with different global climatic oscillations such as QuasiBiennial Oscillation (QBO) (Rao and Lakhole 1978;Vijayakumar and Kulkarni 1995;Claud and Pascal 2007), tidal forcing (Campbell et al 1983), El Nino Southern Oscillation (ENSO) (Shukla and Paolino 1983;Mooley and Parthasarathy 1983;Krishnakumar et al 1999;Gadgil et al 2004), Atlantic Multidecadal Oscillation (AMO) (Goswami et al 2006;Lu et al 2006;Zhang and Delworth 2006;Feng and Hu 2008); Equatorial Indian Ocean Oscillation (EQUINOO) (Gadgil et al 2004;Maity and Nagesh Kumar 2006a;Nagesh Kumar et al 2007), solar indices of sunspot cycle (SN), solar irradiance and sunspot area (Bhalme and Jadhav 1984;Krishnakumar et al 1999;Bhattcharya and Narasimha 2007;Azad 2011) etc.…”

Section: Related Workmentioning

confidence: 98%

Time–frequency characterization of sub-divisional scale seasonal rainfall in India using the Hilbert–Huang transform

Reddy

Adarsh

2015

Stoch Environ Res Risk Assess

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Time-frequency characterization is useful in understanding the nonlinear and non-stationary signals of the hydro-climatic time series. The traditional Fourier transform, and wavelet transform approaches have certain limitations in analyzing non-linear and non-stationary hydro-climatic series. This paper presents an effective approach based on the Hilbert-Huang transform to investigate time-frequency characteristics, and the changing patterns of sub-divisional rainfall series in India, and explored the possible association of monsoon seasonal rainfall with different global climate oscillations. The proposed approach integrates the complete ensemble empirical mode decomposition with adaptive noise algorithm and normalized Hilbert transform method for analyzing the spectral characteristics of two principal seasonal rainfall series over four meteorological subdivisions namely Assam-Meghalaya, Kerala, Orissa and Telangana subdivisions in India. The Hilbert spectral analysis revealed the dynamic nature of dominant time scales for two principal seasonal rainfall time series. From the trend analysis of instantaneous amplitudes of multiscale components called intrinsic mode functions (IMFs), it is found that both intra and inter decadal modes are responsible for the changes in seasonal rainfall series of different subdivisions and significant changes are noticed in the amplitudes of inter decadal modes of two seasonal rainfalls in the four subdivisions since 1970s. Further, the study investigated the links between monsoon rainfall with the global climate oscillations such as Quasi Bienniel Oscillation (QBO), El Nino Southern Oscillation (ENSO), Sunspot Number (SN), Atlantic Multidecadal Oscillation (AMO) etc. The study noticed that the multiscale components of rainfall series IMF1, IMF2, IMF3, IMF4 and IMF5 have similar periodic structure of QBO, ENSO, SN, tidal forcing and AMO respectively. As per the seasonal rainfall patterns is concerned, the results of the study indicated that for Assam-Meghalaya subdivision, there is a likelihood of extreme rare events at *0.2 cycles per year, and both monsoon and pre-monsoon rainfall series have decreasing trends; for Kerala subdivision, extreme events can be expected during monsoon season with shorter periodicity (*2.5 years), and monsoon rainfall has statistically significant decreasing trend and post-monsoon rainfall has a statistically significant increasing trend; and for Orissa subdivision, there are chances of extremes rainfall events in monsoon season and a relatively stable rainfall pattern during post-monsoon period, but both monsoon and post-monsoon rainfall series showed an overall decreasing trend; for Telangana subdivision, there is a likelihood of extreme events during monsoon season with a periodicity of *4 years, but both monsoon and post-monsoon rainfall series showed increasing trends. The results of correlation analysis of IMF components of monsoon rainfall and five climate indices indicated that the association is expressed well only for low frequency modes wit...

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Seasonal Weather and its Prediction*

Cited by 23 publications

References 0 publications

Role of Antarctic circumpolar wave in modulating the extremes of Indian summer monsoon rainfall

Role of Antarctic circumpolar wave in modulating the extremes of Indian summer monsoon rainfall

Eastward propagating MJO during boreal summer and Indian monsoon droughts

Time–frequency characterization of sub-divisional scale seasonal rainfall in India using the Hilbert–Huang transform

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