Combining regional moist static energy and ENSO for forecasting of early and late season Indian monsoon rainfall and its extremes

Rajagopalan, Balaji; Molnár, Péter

doi:10.1002/2014gl060429

Cited by 27 publications

(10 citation statements)

References 50 publications

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“…Parts of northern India remain sensitive throughout the entire season. These differences emphasize the importance of examining the monsoon on a subseasonal timescale, which has been acknowledged in other recent studies [Singh et al, 2014;Pattanaik, 2012;Rajagopalan and Molnar, 2014].…”

Section: Discussionmentioning

confidence: 87%

Subseasonal variations in spatial signatures of ENSO on the Indian summer monsoon from 1901 to 2009

2015

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Correlations of 1 ∘ by 1 ∘ seasonal rainfall with Pacific sea surface temperatures (SSTs) reveal spatially distinct teleconnections between El Niño-Southern Oscillation (ENSO) and Indian summer monsoon rainfall over the full monsoon season, as well as three subseasons. Over the full season (June-September), Pacific SSTs correlate with rainfall in Western India more than that in Eastern India. This spatial signature shifts as the monsoon progresses through early (June), middle or peak (July-August), and late (September) subseasons. Specifically, a 1 ∘ C cooling of the central equatorial Pacific (i.e., La Niña conditions) can result in the following: ∼70-100% increase in precipitation in north central Indian and the Indo-Gangetic Plains during the early season, ∼30-80% increase peak season precipitation in south central India and northwestern Rajasthan, and ∼60-100% increase in late season precipitation in northern, northwestern, and central India. Furthermore, the spatial signatures between La Niña and El Niño are asymmetric in that for a particular location, the enhancement and suppression of rainfall associated with La Niña and El Niño conditions, respectively, are not equal. El Niño suppresses peak season rainfall in the south central and northwestern Rajasthan regions more than La Niña enhances it, but the opposite occurs during the late season in northern, northwestern, and central India. Additionally, the correspondence of minima (maxima) in anomalies of velocity potential aloft with maxima (minima) at 925 mb and with positive (negative) surface pressure anomalies suggests that anomalous subsidence (ascent) occurs in July-September during El Niño (La Niña) times. In the early season, however, patterns of velocity potential composites suggest a region of descent (ascent) over the western equatorial Indian Ocean, along with a region of ascent (descent) over the Indian subcontinent that exists only during the early season but not during the peak or late season. These patterns are consistent with the hypothesis that local Hadley cell circulation affects pressure and thus rainfall during the early season but that a larger-scale mechanism, such as eastward or westward shifts in the Walker circulation, may be more responsible for teleconnections seen throughout the remainder of the season. These findings indicate that focusing monsoon forecasting efforts on these regions and on subseasonal periods while incorporating ENSO asymmetries will yield useful and skillful regional forecasts, compared to the declining utility and skill of all-India summer monsoon rainfall.

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Section: Discussionmentioning

confidence: 87%

Subseasonal variations in spatial signatures of ENSO on the Indian summer monsoon from 1901 to 2009

2015

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“…In these cases, the onset dates can be predicted in lead‐times of a month (or more) using rain gauge data. Rajagopalan and Molnar () showed that a non‐linear regression model can predict precipitation around the onset and withdrawal periods over the Indian monsoon using moist static energy over the subcontinent and an ENSO index as independent variables.…”

Section: Predictability Of Monsoon Onset and Ending Datesmentioning

confidence: 99%

Detection, variability, and predictability of monsoon onset and withdrawal dates: A review

Bombardi

Moron

Goodnight

2019

Intl Journal of Climatology

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This article presents a review of the scientific literature on detection, sources of variability, and predictability of the timing of monsoons. The timing of monsoons is characterized by the beginning (commonly referred to as onset) and end (commonly referred to as demise, cessation, retreat, or withdrawal) dates of the summer monsoons. The main methods used to detect the timing of monsoons are divided into two categories: local‐scale methods and regional to large‐scale methods. The sources of variability of the timing of monsoons are also separated into two categories: local‐scale and large‐scale sources. Finally, the article presents a summary of the literature on the predictability of the timing of monsoons using both dynamical and statistical approaches. We show that all methods are parameterized in some way. A comparison between two different methods shows that while there might be large differences in the definition of onset and demise dates at the local level, spatial aggregation usually reduces the noise and enhances the regional monsoonal signal, which may be predictable.

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“…The effect of Eurasian snow cover reduces the midtropospheric heating over the TP and the meridional temperature gradient (Blanford, ; Vernekar et al, ). Using the surface moist static energy over the Indian subcontinent and the Niño4 index, the predictive skill of ISM onset is improved (Rajagopalan & Molnar, ). In light of the geographic concept, the air temperature and relative humidity over the Northern Pakistan and the Eastern Ghats have suggested the critical behavior which has good prediction than existing methods (Stolbova et al, ).…”

Section: Introductionmentioning

confidence: 99%

Early Indian Summer Monsoon Onset Driven by Low Soil Moisture in the Iranian Desert

Moon

2019

Geophysical Research Letters

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Advancing the leading time for onset prediction of the Indian summer monsoon (ISM) onset is an imperative task; however, it has remained a challenging subject. In particular, the land‐atmosphere coupling associated with monsoon onset prediction is poorly understood. Here we attempt to investigate the land factor as the ISM onset precursor through studying the internal mechanism of atmospheric heating, which is distinguished by monsoon onset. The low (high) soil moisture in the Iranian desert during March and April advances (delays) ISM onset by enhancing (disturbing) the vertical easterly wind shear. In addition, midtropospheric heating is affected by soil moisture in the Iranian desert. By investigating the internal atmospheric heating process and suggesting the relationship between low soil moisture and ISM onset, these findings clarify the monsoon onset mechanism in terms of the vertical atmospheric profile and land‐atmosphere interaction, which eventually extend the lead time for the onset prediction.

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Combining regional moist static energy and ENSO for forecasting of early and late season Indian monsoon rainfall and its extremes

Cited by 27 publications

References 50 publications

Subseasonal variations in spatial signatures of ENSO on the Indian summer monsoon from 1901 to 2009

Subseasonal variations in spatial signatures of ENSO on the Indian summer monsoon from 1901 to 2009

Detection, variability, and predictability of monsoon onset and withdrawal dates: A review

Early Indian Summer Monsoon Onset Driven by Low Soil Moisture in the Iranian Desert

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