Tropical Indian Ocean subsurface temperature variability and the forcing mechanisms

Ojha, Sayantani; Gnanaseelan, C.

doi:10.1007/s00382-014-2379-y

Cited by 59 publications

(31 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This thicker barrier layer would favor anomalous warming above the thermocline, which would intensify the air‐sea coupling over the southwestern Indian Ocean and the precipitation. The light fresh water, in turn, stabilizes the barrier layer [ Chowdary et al , ; Sayantani and Gnanaseelan , ]. A detailed mechanism should be clarified in a future study.…”

Section: Discussionmentioning

confidence: 99%

Interannual modulation of East African early short rains by the winter Arctic Oscillation

et al. 2016

View full text Add to dashboard Cite

In the present study, we analyzed the interannual linkage between the boreal winter Arctic Oscillation (AO) and East African early short rains. When the Indian Ocean Dipole and El Niño–Southern Oscillation variance are excluded by linear regression, the boreal winter AO index is significantly correlated with the October East African precipitation over the domain of 5°N–5°S and 35°–45°E for the period 1979–2014, r =+ 0.46. The upper ocean heat content likely acts as a medium that links the AO and East African precipitation. Significant subsurface warming and positive upper ocean heat content anomalies occur over the western Indian Ocean during the autumn following positive AO winters, which enriches the atmospheric moisture, intensifies convection, and enhances precipitation. Oceanic dynamics play a key role in causing this subsurface warming. Winter AO‐related atmospheric circulation creates anomalous wind stress, which forces a downwelling oceanic Rossby wave between 60°–75°E and 5°–10°S, where the thermocline significantly deepens. This Rossby wave propagates westward and accompanies significant subsurface warming along the thermocline. The Rossby wave arrives at the western Indian Ocean in the late summer, significantly warming the region to the west of 55°E at a depth of 60–100 m. This warming remains significant through October. Correspondingly, the upper ocean heat content significantly increases by approximately 2–3 × 108 J m−2 in the region west of 60°E between 5° and 10°S. The role of these oceanic dynamics in linking the winter AO, and anomalous subsurface warming was tested by numerical experiments with an oceanic general circulation model. The experiments were performed with the forcing of AO‐related wind stress anomalies over the Indian Ocean in the winter. The oceanic Rossby wave generated in the central Indian Ocean during boreal winter, the consequent subsurface warming, and the anomalous upper ocean heat content in October over the western Indian Ocean were all adequately reproduced. The winter AO can serve as a precursor of East African short rain anomalies.

show abstract

Section: Discussionmentioning

confidence: 99%

Interannual modulation of East African early short rains by the winter Arctic Oscillation

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The major variability in sea level is seen over the BoB, eastern equatorial Indian Ocean and SCTR region. This in fact forces a north south asymmetry in the SLA similar to the one reported by Sayantani and Gnanaseelan () in the subsurface temperature. The SLA associated with pure IODs is found to be initiated about a season ahead of such anomalies of the co‐occurrence years.…”

Section: The Interannual Sea Level Variability In the Indian Oceanmentioning

confidence: 99%

The interannual sea level variability in the Indian Ocean as simulated by an Ocean General Circulation Model

Deepa

Gnanaseelan

Kakatkar

et al. 2017

Intl Journal of Climatology

Self Cite

View full text Add to dashboard Cite

The study finds that co‐occurrence years (years when IOD and El Niño events co‐occur) contribute significantly towards the interannual variability in the Indian Ocean. Carefully designed Ocean General Circulation Model (OGCM) captured the observed variability. The OGCM experiments are carried out by modulating the forcing fields over the Pacific and the Indian Ocean to understand the physical mechanisms causing sea level variability in the Indian Ocean. Decadal variability in the ENSO is primarily contributing to the decadal variability in the Indian Ocean sea level.

show abstract

“…IOD and MJO are some of the ocean-atmosphere-coupled phenomena affected by variations in these forcing and feedback mechanisms, and thus induce significant changes in the tropical weather patterns. North-South subsurface dipole is another mode of variability observed in the tropical Indian Ocean, caused by subsurface temperature change and resembling the patterns of IOD (both phases) and El Niño co-occurrence years 18 . Cloud cover, winds, radiation fluxes, precipitation, and evaporation are the atmospheric parameters that influence the EIO 19,20 .…”

Section: Introductionmentioning

confidence: 85%

A sea-level monopole in the equatorial Indian Ocean

et al. 2020

View full text Add to dashboard Cite

In this study, we show the relationship between sea-level anomalies (SLA) and upper-ocean parameters in the Equatorial Indian Ocean (EIO). This work also focuses on the variability of SLA obtained from satellite altimeter data in different spatial and temporal scales and its relationship with computed ocean heat content (OHC), dynamic height (DH), and thermocline depth (20°C isotherm: D20) during 1993-2015. SLA showed low Pearson's correlation coefficient (CC) with upper-ocean parameters over central EIO resembling a "Monopole" pattern. The Array for Real-time Geostrophic Oceanography (ARGO) in situ profile data in the central EIO also confirmed this. SLA over this monopole showed low correlations with all parameters as compared with eastern and western EIO. These findings show a clear signature of a persisting sea-level monopole in the central EIO. Oscillating SLA over western and eastern EIO during summer and winter monsoon months is found to be responsible for locking this monopole in the central EIO.

show abstract

Tropical Indian Ocean subsurface temperature variability and the forcing mechanisms

Cited by 59 publications

References 40 publications

Interannual modulation of East African early short rains by the winter Arctic Oscillation

Interannual modulation of East African early short rains by the winter Arctic Oscillation

The interannual sea level variability in the Indian Ocean as simulated by an Ocean General Circulation Model

A sea-level monopole in the equatorial Indian Ocean

Contact Info

Product

Resources

About