Detection of Intraseasonal Oscillations in SMAP Salinity in the Bay of Bengal

Subrahmanyam, Bulusu; Trott, Corinne B.; Murty, V. S. N.

doi:10.1029/2018gl078662

Cited by 37 publications

(38 citation statements)

References 35 publications

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“…The Aquarius products' signals remain the lowest in amplitude among the available salinity satellites but spatially consistent with previous MJO studies on the order of ±0.1 psu (Grunseich et al, ; Li et al, ). The oscillatory response of SMAP SSS to MJO forcing is on the order of ±0.2 psu and consistent with Subrahmanyam et al (). SMOS exhibits a similar response to SMAP at ±0.2 psu in the Hovmöller and spatial figures (Figures and ).…”

Section: Resultssupporting

confidence: 89%

“…Studying SSS variability during MJO propagation will allow for a better understanding of air‐sea interaction associated with the MJO, especially due to technological advancements of the past decades transitioning from spatially scarce in situ methods to globally expansive, high spatiotemporal resolution satellite‐derived methods. The MJO has been detected in satellite‐derived salinity from the European Space Agency's Soil Moisture Ocean Salinity (SMOS; Maes et al, ), the National Aeronautics and Space Administration (NASA)'s Aquarius/SAC‐D (Grunseich et al, ; Guan et al, ; Shinoda et al, ), and NASA's Soil Moisture Active Passive (SMAP; Subrahmanyam et al, ) missions. Similarly, comparisons of Aquarius/SAC‐D and SSS output from the HYbrid Coordinate Ocean Model have shown that both can capture near equatorial MJO‐induced SSS variability (Li et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Madden‐Julian Oscillation‐Induced Sea Surface Salinity Variability as Detected in Satellite‐Derived Salinity

Shoup

Subrahmanyam

Roman‐Stork

2019

Geophysical Research Letters

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As a dominant source of tropical variability, the Madden‐Julian oscillation (MJO) influences the ocean in many ways. One approach to observe the atmosphere‐ocean relationship is by examining sea surface salinity (SSS) due to direct freshening by MJO precipitation. The convectively enhanced (suppressed) phase of the MJO is associated with negative (positive) SSS anomalies that propagate eastward along the equatorial Indian and Pacific oceans. In this study, primary MJO events are identified, and their SSS signatures are compared for the first time across multiple satellite salinity products (the European Space Agency's Soil Moisture Ocean Salinity; the National Aeronautics and Space Administration's Aquarius and Soil Moisture Active Passive) from 2010 to 2017. While all satellite missions are capable of detecting MJO signals and primary events on an unprecedented observational scale, we find that the use of the combined active passive algorithm increases signal robustness, with the strongest signal response in Soil Moisture Active Passive and Soil Moisture Ocean Salinity (±0.2 psu) and the lowest in Aquarius (±0.1 psu).

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Madden‐Julian Oscillation‐Induced Sea Surface Salinity Variability as Detected in Satellite‐Derived Salinity

Shoup

Subrahmanyam

Roman‐Stork

2019

Geophysical Research Letters

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“…The high temporal resolution of satellite SSS enabled a better understanding of large-scale intra-seasonal phenomena (e.g., Subrahmanyam et al, 2018), including the Madden-Julian Oscillation (MJO) -the dominant climate mode at sub-seasonal time scales in the tropics that impacts the global weather and climate (Zhang, 2005). Satellite SSS measurements enable characterization of the SSS signature associated with MJO and the associated impacts on surface density variations (Grunseich et al, 2013;Guan et al, 2014;Li et al, 2015), emphasizing the role of upper-ocean dynamics in regulating MJO.…”

Section: Scientific Drivers For Satellite Salinity Improving Knowledgmentioning

confidence: 99%

Satellite Salinity Observing System: Recent Discoveries and the Way Forward

et al. 2019

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Advances in L-band microwave satellite radiometry in the past decade, pioneered by ESA's SMOS and NASA's Aquarius and SMAP missions, have demonstrated an unprecedented capability to observe global sea surface salinity (SSS) from space. Measurements from these missions are the only means to probe the very-near surface salinity (top cm), providing a unique monitoring capability for the interfacial exchanges of water between the atmosphere and the upper-ocean, and delivering a wealth of information on various salinity processes in the ocean, linkages with the climate and water cycle, including land-sea connections, and providing constraints for ocean prediction models. The satellite SSS data are complimentary to the existing in situ systems such as Argo that provide accurate depiction of large-scale salinity variability in the open ocean but under-sample mesoscale variability, coastal oceans and marginal seas, and energetic regions such as boundary currents and fronts. In particular, salinity remote sensing has proven valuable to systematically monitor the open oceans as well as coastal regions up to approximately 40 km from the coasts. This is critical to addressing societally relevant topics, such as land-sea linkages, coastal-open ocean exchanges, research in the carbon cycle, near-surface mixing, and air-sea exchange of gas and mass. In this paper, we provide a community perspective on the major achievements of satellite SSS for the aforementioned topics, the unique capability of satellite salinity observing system and its complementarity with other platforms, uncertainty characteristics of satellite SSS, and measurement versus sampling errors in relation to in situ salinity measurements. We also discuss the need for technological innovations to improve the accuracy, resolution, and coverage of satellite SSS, and the way forward to both continue and enhance salinity remote sensing as part of the integrated Earth Observing System in order to address societal needs.

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“…SMAP is available from 2015 to present. Satellite-derived salinity has been used in several studies of the Indian Ocean but is underutilized in monsoon studies on the whole (Murty et al, 2004;Nyadjro et al, 2012;Nyadjro & Subrahmanyam, 2016;Paris & Subrahmanyam, 2018;Subrahmanyam et al, 2018).…”

Section: Data 211 Reanalysis Productsmentioning

confidence: 99%

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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Detection of Intraseasonal Oscillations in SMAP Salinity in the Bay of Bengal

Cited by 37 publications

References 35 publications

Madden‐Julian Oscillation‐Induced Sea Surface Salinity Variability as Detected in Satellite‐Derived Salinity

Madden‐Julian Oscillation‐Induced Sea Surface Salinity Variability as Detected in Satellite‐Derived Salinity

Satellite Salinity Observing System: Recent Discoveries and the Way Forward

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

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