Tracking the Indian Summer Monsoon Onset Back to the Preinstrument Period

Ordóñez, Paulina; Gallego, David; Ribera, Pedro; Peña‐Ortiz, Cristina; García‐Herrera, Ricardo

doi:10.1175/jcli-d-15-0788.1

Cited by 25 publications

(29 citation statements)

References 51 publications

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“…Monsoon onset data were obtained from the India Meteorological Department, as well as previous studies (Ordoñez et al, ; Pai & Rajeevan, ). ENSO phases are based on the NOAA and NCEP Oceanic Niño Index and a previous study by Grunseich et al ().…”

Section: Methodsmentioning

confidence: 99%

“…IOD phases are obtained from the Australian Bureau of Meteorology as annual phases. Monsoon regimes (strong, weak, or normal) data are also obtained from IITM, and these regimes are based on a 10% departure from the long‐term mean, where a season with more (less) than 10% of the long‐term mean would be a strong (weak) monsoon (Ordoñez et al, ; Pai & Rajeevan, ).…”

Section: Methodsmentioning

confidence: 99%

“…Monsoon rainfall totals were taken from IITM at ftp://www.tropmet.res.in/pub/data/rain/iitm-regionrf.txt. Monsoon onset data for Table were obtained from the India Meteorological Department (IMD), as well as previous studies by Pai and Rajeevan () and Ordoñez et al (). El Niño Southern Oscillation (ENSO) phases were based on the NOAA and National Center for Environment Prediction (NCEP) Oceanic Niño Index (ONI) and a previous study by Grunseich et al ().…”

Section: Acknowledgmentsmentioning

confidence: 99%

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The Role of Salinity in the Southeastern Arabian Sea in Determining Monsoon Onset and Strength

2020

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In this study, we examine the role of freshwater transported from the Bay of Bengal into the southeastern Arabian Sea (SEAS) in determining both the timing of monsoon onset and the strength of the ensuing monsoon. To do this, we use a combination of satellite-derived salinity data and reanalysis products from 1980 to 2016 in order to discuss seasonal, interannual, subdecadal, and long-term decadal variability in various atmospheric and oceanic contributors such as ocean heat content, freshwater transport, ERA5 instantaneous moisture flux, mixed layer depth, and barrier layer thickness. The salt budget in the SEAS reveals the dominance of meridional freshwater advective transport that brings in variability in salinity and thus in salinity stratification, as well as in mixed layer processes. We find that these parameters exhibit the prevalence of a long-term decadal variability (with trends of increasing/decreasing phases over a 15-year duration) over which interannual (3-year trend) and intradecadal (7-year trend) variability trends are superimposed. The patterns of both the 3-and 7-year trends follow each other closely, and relatively high amplitudes are seen in the 3-year trends. The long-term decrease in moisture flux and freshwater transport into the SEAS along with a rise in ocean heat content over a 15-year duration after 1994 contributed to a lack of strong monsoons in recent years; the prevailing interannual and intradecadal variability in these parameters associated with the Indian Ocean Dipole and El Niño Southern Oscillation events favored weaker and normal monsoons after 1994. Plain Language SummaryThe timing and intensity of the southwest monsoon is difficult to forecast and has been the subject of a great deal of research. In particular, the genesis of a monsoon onset vortex over the southeastern Arabian Sea (SEAS) encompassing the Arabian Sea Mini Warm Pool has received increased attention for the role it plays on the onset of the southwest monsoon. In our study, we examine how the low salinity waters transported from the Bay of Bengal (both along the east coast of India and from the southern Bay of Bengal) into the SEAS region influence the strength and timing of the ensuing southwest monsoon. Our finding is that this low salinity water has a significant impact on barrier layer formation in the SEAS and the vertical thermal structure of the Arabian Sea Mini Warm Pool. Further examination of subdecadal, decadal, and long-period decadal trends from 1980 to 2016 shows that instantaneous moisture fluxes and zonal winds over the SEAS have decreased substantially, and barrier layer thickness has increased since 1994 in association with the increasing trend in ocean heat content and contributed to the lack of strong southwest monsoons after 1994.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Acknowledgmentsmentioning

confidence: 99%

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The Role of Salinity in the Southeastern Arabian Sea in Determining Monsoon Onset and Strength

2020

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“…Using historical meteorological records taken aboard ships, Ordoñez et al . () were able to calculate the onset of the Indian monsoon over Kerala using wind data dating back to 1870 (although some periods have very low data coverage, see text for details).…”

Section: Defining Onset and End 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 criterion used to define onset from daily rainrate is similar to that used in [26,5]. Moreover, the criterion for lower and middle tropospheric winds in defining onset has been used in several previous studies [6,[27][28][29]. The use of a combined rain and wind criteria for determination of onset date minimises the possibility of capturing pre-onset heavy rainfall as bogus onset.…”

Section: Data Sets and The Definition Of Onsetmentioning

confidence: 99%