Application of Extended Empirical Orthogonal Function Analysis to Interrelationships and Sequential Evolution of Monsoon Fields

Singh, S. V.; Kripalani, R. H.

doi:10.1175/1520-0493(1986)114<1603:aoeeof>2.0.co;2

Cited by 31 publications

(18 citation statements)

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“…Over the Indian summer monsoon region, canonical northward-propagating 30-60-day ISO events have been observed and documented in detail (e.g., Yasunari 1979Yasunari , 1980Yasunari , 1981Sikka and Gadgil 1980;Krishnamurti and Subrahmanyam 1982;Singh andKripalani 1985, 1986;Wang and Rui 1990;Kemball-Cook and Wang 2001). The ISO characteristics, shown in Fig.…”

Section: Evolution Of the Large-scale Circulation Associated With Thementioning

confidence: 94%

Objective Definition of the Indian Summer Monsoon Onset*

2009

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The onset of the Indian summer monsoon (ISM) over the southern tip of the Indian peninsula [also known as monsoon onset over Kerala (MOK)] has been considered the beginning of India's rainy season. The Indian Meteorological Department (IMD) makes an official prediction of ISM onset every year using a subjective method. Based on an analysis of the past 60-yr (1948-2007) record, the authors show that the onset date can be objectively determined by the beginning of the sustained 850-hPa zonal wind averaged over the southern Arabian Sea (SAS) from 58 to 158N, and from 408 to 808E. The rapid establishment of a steady SAS westerly is in excellent agreement with the abrupt commencement of the rainy season over the southern tip of the Indian peninsula. In 90% of the years analyzed, this simple and objective index has excellent agreement with the onset dates that are subjectively defined by the IMD. There are only 3 yr of the past 60 yr during which the two onset dates differ by more than 10 days, and none of them perfectly reflects the MOK.A prominent onset precursor on the biweekly time scale is the westward extension of the convection center from the equatorial eastern Indian Ocean toward the southeast Arabian Sea. On the intraseasonal time scale, the onset tends to be led by northeastward propagation of an intraseasonal convective anomaly from the western equatorial Indian Ocean. The objective determination of the onset based on the SAS low-level westerly is a characteristic representation of the complex process of the ISM onset. Given its objectiveness and its representation of the large-scale circulation, the proposed new onset definition provides a useful metric for verifying numerical model performance in simulating and predicting the ISM onset and for studying predictability of interannual variations of the onset.

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Section: Evolution Of the Large-scale Circulation Associated With Thementioning

confidence: 94%

Objective Definition of the Indian Summer Monsoon Onset*

2009

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“…This makes finding the CCA rather easy and also gives a way of choosing the data based on the explained variance. This procedure and not the extended empirical orthogonal function (EOF) analysis method used in Singh and Kripalani (1986) has been used in the present study. Details about the CCA are available in Graham et al (1987) and Wilks (1995).…”

Section: Canonical Correlation Analysis (Cca)mentioning

confidence: 99%

Prediction of Indian summer monsoon rainfall (ISMR) using canonical correlation analysis of global circulation model products

Singh¹,

Kulkarni

Mohanty³

et al. 2012

Meteorological Applications

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ABSTRACT:The Canonical Correlation Analysis (CCA) method has been used in this study for improving General Circulation Model (GCM) predicted rainfall over India during the southwest monsoon season. Hindcast runs for 27 years from six GCM outputs are used. This statistical technique relates the pattern of multivariate predictor field (model rainfall) to the pattern of predictand fields (observed rainfall). It is found that the CCA method improves the skill of three of the GCMs at the all-India level. A noticeable improvement is also observed in the composite prediction with CCA as compared to the simple mean of raw GCM products. The skill of the composite prediction after applying CCA is higher compared to the simple mean of raw model products in several homogeneous zones such as the hilly areas, west central area and over some parts of northwest India. The possible reason for the improvement in the skill of some of the GCMs may be the similarity between the loading patterns of model predictions and the observed rainfall.

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“…Simultaneously, 10-12 days later precipitation peaks all along the west coast and along the line running across India between 20°-25°N. The precipitation maxima then spreads slowly northward and loses significance (Singh and Kripalani, 1986;Hartmann and Michelsen, 1989). Figure 6 (right panel) depicts the intensity of 10-20 days oscillations.…”

Section: Intensity Of Dominant Periodicitiesmentioning

confidence: 97%

“…The eastward moving component of the 30-60 days oscillations is also known as Madden-Julian oscillations [(MJOs), Julian, 1971, 1994]. One component of these oscillations propagate poleward over Indian landmass during boreal summer (Sikka and Gadgil, 1980;Singh and Kripalani, 1985, 1986, 1990Kripalani et al, 1991). This northward propagating component of 30-60 days oscillations from the equatorial Indian ocean is popularly known as boreal summer intra-seasonal oscillations (BSISO).…”

Section: Introductionmentioning

confidence: 99%

Spatial variability of intra‐seasonal oscillations during extreme Indian monsoons

Kulkarni

Sabade

Kripalani

2009

Intl Journal of Climatology

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ABSTRACT:The intra-seasonal variability of the Indian monsoon rainfall plays a dominant role in deciding the seasonal strength of the monsoon. The Indian monsoon is known to exhibit two dominant periodicities of intra-seasonal oscillations (ISOs) 30-60 days and 10-20 days on the spatial scale of entire landmass. In this paper the nature and intensity of these dominant periodicities have been studied on smaller spatial domains during all-India deficient and excess monsoons. The high resolution data 1°× 1°latitude/longitude over Indian domain for the recent period of 1951-2003 provided by India Meteorological Department have been used in this analysis. The multi-taper spectrum analysis (MTMA) method has been applied to identify the periodicities over four representative regions. The 30-60 days periodicity is dominant over west coast and South-east India during deficient monsoons while the excess monsoons are characterized by high frequency oscillations. The time variation of these periodicities is studied by applying wavelet transforms (WTs).During deficient Indian monsoons coherent regions with dominant oscillations are observed. Empirical Orthogonal Function (EOF) analysis reveals that both the oscillations have weakened after mid 1970s. Implications of this on forecasting Indian monsoon are discussed.

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Application of Extended Empirical Orthogonal Function Analysis to Interrelationships and Sequential Evolution of Monsoon Fields

Cited by 31 publications

References 0 publications

Objective Definition of the Indian Summer Monsoon Onset*

Objective Definition of the Indian Summer Monsoon Onset*

Prediction of Indian summer monsoon rainfall (ISMR) using canonical correlation analysis of global circulation model products

Spatial variability of intra‐seasonal oscillations during extreme Indian monsoons

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