The Atmospheric General Circulation in Thermodynamical Coordinates
The Atmospheric General Circulation in Thermodynamical Coordinates
The zonal and meridional components of the atmospheric general circulation are used to define a global thermodynamic streamfunction in dry static energy versus latent heat coordinates. Diabatic motions in the tropical circulations and fluxes driven by midlatitude eddies are found to form a single, global thermodynamic cycle. Calculations based on the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset indicate that the cycle has a peak transport of 428 Sv (Sv ? 109 kg s?1). The thermodynamic cycle encapsulates a globally interconnected heat and water cycle comprising ascent of moist air where latent heat is converted into dry static energy, radiative cooling where dry air loses dry static energy, and a moistening branch where air is warmed and moistened. It approximately follows a tropical moist adiabat and is bounded by the Clausius–Clapeyron relationship for near-surface air. The variability of the atmospheric general circulation is related to ENSO events using reanalysis data from recent years (1979–2009) and historical simulations from the EC-Earth Consortium (EC-Earth) coupled climate model (1850–2005). The thermodynamic cycle in both EC-Earth and ERA-Interim widens and weakens with positive ENSO phases and narrows and strengthens during negative ENSO phases with a high correlation coefficient. Weakening in amplitude suggests a weakening of the large-scale circulation, while widening suggests an increase in mean tropical near-surface moist static energy.
916-928
Kjellsson, Joakim
386ed501-47f6-40a0-98a6-3fa741d02081
Döös, Kristofer
f983e388-b9e9-4405-a51d-adf432410c2e
Laliberté, Frédéric B.
e469ff30-63a8-4825-a7a9-ab733826b6d3
Zika, Jan D.
1843cce7-77ce-4ef6-9f79-bcf4f9db30e5
March 2014
Kjellsson, Joakim
386ed501-47f6-40a0-98a6-3fa741d02081
Döös, Kristofer
f983e388-b9e9-4405-a51d-adf432410c2e
Laliberté, Frédéric B.
e469ff30-63a8-4825-a7a9-ab733826b6d3
Zika, Jan D.
1843cce7-77ce-4ef6-9f79-bcf4f9db30e5
Kjellsson, Joakim, Döös, Kristofer, Laliberté, Frédéric B. and Zika, Jan D.
(2014)
The Atmospheric General Circulation in Thermodynamical Coordinates.
Journal of the Atmospheric Sciences, 71 (3), .
(doi:10.1175/JAS-D-13-0173.1).
Abstract
The zonal and meridional components of the atmospheric general circulation are used to define a global thermodynamic streamfunction in dry static energy versus latent heat coordinates. Diabatic motions in the tropical circulations and fluxes driven by midlatitude eddies are found to form a single, global thermodynamic cycle. Calculations based on the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset indicate that the cycle has a peak transport of 428 Sv (Sv ? 109 kg s?1). The thermodynamic cycle encapsulates a globally interconnected heat and water cycle comprising ascent of moist air where latent heat is converted into dry static energy, radiative cooling where dry air loses dry static energy, and a moistening branch where air is warmed and moistened. It approximately follows a tropical moist adiabat and is bounded by the Clausius–Clapeyron relationship for near-surface air. The variability of the atmospheric general circulation is related to ENSO events using reanalysis data from recent years (1979–2009) and historical simulations from the EC-Earth Consortium (EC-Earth) coupled climate model (1850–2005). The thermodynamic cycle in both EC-Earth and ERA-Interim widens and weakens with positive ENSO phases and narrows and strengthens during negative ENSO phases with a high correlation coefficient. Weakening in amplitude suggests a weakening of the large-scale circulation, while widening suggests an increase in mean tropical near-surface moist static energy.
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Published date: March 2014
Organisations:
Physical Oceanography
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Local EPrints ID: 363428
URI: http://eprints.soton.ac.uk/id/eprint/363428
ISSN: 1520-0469
PURE UUID: ff2f0c5d-ca5e-45f1-bb08-0ef3c47ecd8c
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Date deposited: 24 Mar 2014 15:21
Last modified: 14 Mar 2024 16:24
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Author:
Joakim Kjellsson
Author:
Kristofer Döös
Author:
Frédéric B. Laliberté
Author:
Jan D. Zika
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