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Title: Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing

Abstract

The large-scale and long-term climate impacts of anthropogenic sulfate aerosols consist of Northern Hemisphere cooling and a southward shift of the tropical rain belt. On interannual time scales, however, the response to aerosols is localized with a sizable imprint on local ocean–atmosphere interaction. A large concentration of anthropogenic sulfates over Asia may impact ENSO by modifying processes and interactions that generate this coupled ocean–atmosphere variability. Here, we use climate model experiments with different degrees of ocean–atmosphere coupling to study the tropical Pacific response to an abrupt increase in anthropogenic sulfates. These include an atmospheric general circulation model (GCM) coupled to either a full-ocean GCM or a slab-ocean model, or simply forced by climatology of sea surface temperature. Comparing the responses helps differentiate between the fast atmospheric and slow ocean-mediated responses, and highlights the role of ocean–atmosphere coupling in the latter. We demonstrate the link between the Walker circulation and the equatorial Pacific upper-ocean dynamics in response to increased sulfate aerosols. The local surface cooling due to sulfate aerosols emitted over the Asian continent drives atmospheric subsidence over the equatorial west Pacific. The associated anomalous circulation imparts westerly momentum to the underlying Pacific Ocean, leading to an El Niño–like upper-ocean responsemore » and a transient warming of the east equatorial Pacific Ocean. The oceanic adjustment eventually contributes to its decay, giving rise to a damped oscillation of the tropical Pacific Ocean in response to abrupt anthropogenic sulfate aerosol forcing.« less

Authors:
ORCiD logo [1];  [2];  [2];  [3]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Texas A & M Univ., College Station, TX (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1631253
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Climate
Additional Journal Information:
Journal Volume: 32; Journal Issue: 23; Journal ID: ISSN 0894-8755
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Tropics; Atmosphere-ocean interaction; Ocean dynamics; Aerosols; Climate models; Interannual variability

Citation Formats

Verma, Tarun, Saravanan, R., Chang, P., and Mahajan, S.. Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing. United States: N. p., 2019. Web. https://doi.org/10.1175/JCLI-D-19-0050.1.
Verma, Tarun, Saravanan, R., Chang, P., & Mahajan, S.. Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing. United States. https://doi.org/10.1175/JCLI-D-19-0050.1
Verma, Tarun, Saravanan, R., Chang, P., and Mahajan, S.. Wed . "Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing". United States. https://doi.org/10.1175/JCLI-D-19-0050.1. https://www.osti.gov/servlets/purl/1631253.
@article{osti_1631253,
title = {Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing},
author = {Verma, Tarun and Saravanan, R. and Chang, P. and Mahajan, S.},
abstractNote = {The large-scale and long-term climate impacts of anthropogenic sulfate aerosols consist of Northern Hemisphere cooling and a southward shift of the tropical rain belt. On interannual time scales, however, the response to aerosols is localized with a sizable imprint on local ocean–atmosphere interaction. A large concentration of anthropogenic sulfates over Asia may impact ENSO by modifying processes and interactions that generate this coupled ocean–atmosphere variability. Here, we use climate model experiments with different degrees of ocean–atmosphere coupling to study the tropical Pacific response to an abrupt increase in anthropogenic sulfates. These include an atmospheric general circulation model (GCM) coupled to either a full-ocean GCM or a slab-ocean model, or simply forced by climatology of sea surface temperature. Comparing the responses helps differentiate between the fast atmospheric and slow ocean-mediated responses, and highlights the role of ocean–atmosphere coupling in the latter. We demonstrate the link between the Walker circulation and the equatorial Pacific upper-ocean dynamics in response to increased sulfate aerosols. The local surface cooling due to sulfate aerosols emitted over the Asian continent drives atmospheric subsidence over the equatorial west Pacific. The associated anomalous circulation imparts westerly momentum to the underlying Pacific Ocean, leading to an El Niño–like upper-ocean response and a transient warming of the east equatorial Pacific Ocean. The oceanic adjustment eventually contributes to its decay, giving rise to a damped oscillation of the tropical Pacific Ocean in response to abrupt anthropogenic sulfate aerosol forcing.},
doi = {10.1175/JCLI-D-19-0050.1},
journal = {Journal of Climate},
number = 23,
volume = 32,
place = {United States},
year = {2019},
month = {11}
}

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