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Rain‐induced stratification of the equatorial Indian Ocean and its potential feedback to the atmosphere

Shackelford, K. ORCID:, DeMott, C. A. ORCID:, Van Leeuwen, P. J. ORCID:, Thompson, E. ORCID: and Hagos, S. ORCID: (2022) Rain‐induced stratification of the equatorial Indian Ocean and its potential feedback to the atmosphere. Journal of Geophysical Research: Oceans, 127 (3). e2021JC018025. ISSN 2169-9291

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To link to this item DOI: 10.1029/2021jc018025


Abstract: Surface freshening through precipitation can act to stably stratify the upper ocean, forming a rain layer (RL). RLs inhibit subsurface vertical mixing, isolating deeper ocean layers from the atmosphere. This process has been studied using observations and idealized simulations. The present ocean modeling study builds upon this body of work by incorporating spatially resolved and realistic atmospheric forcing. Fine‐scale observations of the upper ocean collected during the Dynamics of the Madden‐Julian Oscillation field campaign are used to verify the General Ocean Turbulence Model (GOTM). Spatiotemporal characteristics of equatorial Indian Ocean RLs are then investigated by forcing a 2D array of GOTM columns with realistic and well‐resolved output from an existing regional atmospheric simulation. RL influence on the ocean‐atmosphere system is evaluated through analysis of RL‐induced modification to surface fluxes and sea surface temperature (SST). This analysis demonstrates that RLs cool the ocean surface on time scales longer than the associated precipitation event. A second simulation with identical atmospheric forcing to that in the first, but with rainfall set to zero, is performed to investigate the role of rain temperature and salinity stratification in maintaining cold SST anomalies within RLs. Approximately one third, or 0.1°C, of the SST reduction within RLs can be attributed to rain effects, while the remainder is attributed to changes in atmospheric temperature and humidity. The prolonged RL‐induced SST anomalies enhance SST gradients that have been shown to favor the initiation of atmospheric convection. These findings encourage continued research of RL feedbacks to the atmosphere.

Item Type:Article
Divisions:Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
ID Code:103986
Uncontrolled Keywords:ATMOSPHERIC COMPOSITION AND STRUCTURE, Air/sea constituent fluxes, Volcanic effects, BIOGEOSCIENCES, Climate dynamics, Modeling, COMPUTATIONAL GEOPHYSICS, Numerical solutions, CRYOSPHERE, Avalanches, Mass balance, GEODESY AND GRAVITY, Ocean monitoring with geodetic techniques, Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions, Global change from geodesy, GLOBAL CHANGE, Abrupt/rapid climate change, Climate variability, Earth system modeling, Impacts of global change, Land/atmosphere interactions, Oceans, Regional climate change, Sea level change, Solid Earth, Water cycles, HYDROLOGY, Climate impacts, Hydrological cycles and budgets, INFORMATICS, MARINE GEOLOGY AND GEOPHYSICS, Gravity and isostasy, ATMOSPHERIC PROCESSES, Ocean/atmosphere interactions, Tropical meteorology, Climate change and variability, Climatology, General circulation, Regional modeling, Theoretical modeling, Turbulence, OCEANOGRAPHY: GENERAL, Climate and interannual variability, Numerical modeling, NATURAL HAZARDS, Atmospheric, Geological, Oceanic, Physical modeling, Climate impact, Risk, Disaster risk analysis and assessment, NONLINEAR GEOPHYSICS, OCEANOGRAPHY: PHYSICAL, Turbulence, diffusion, and mixing processes, Upper ocean and mixed layer processes, Air/sea interactions, Decadal ocean variability, Ocean influence of Earth rotation, Sea level: variations and mean, Surface waves and tides, Tsunamis and storm surges, PALEOCEANOGRAPHY, POLICY SCIENCES, Benefit‐cost analysis, RADIO SCIENCE, Radio oceanography, SEISMOLOGY, Earthquake ground motions and engineering seismology, Volcano seismology, SPACE PLASMA PHYSICS, VOLCANOLOGY, Volcano/climate interactions, Atmospheric effects, Volcano monitoring, Effusive volcanism, Mud volcanism, Explosive volcanism, Volcanic hazards and risks, Research Article, Surface freshening, air‐sea interaction, tropical convection, ocean stratification
Publisher:American Geophysical Union


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