The Atmospheric General Circulation in Thermodynamical Coordinates
2014 (English)In: Journal of Atmospheric Sciences, ISSN 0022-4928, E-ISSN 1520-0469, Vol. 71, no 3, 916-928 p.Article in journal (Refereed) Published
The zonal and meridional components of the atmospheric general circulation are used to define a global thermodynamic stream function 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 ERA-Interim reanalysis 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 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 reduction in moist convection in the tropics, while widening suggests an increase in mean tropical near-surface moist static energy.
Place, publisher, year, edition, pages
2014. Vol. 71, no 3, 916-928 p.
Climate, Atmosphere, Mass transport, Stream function, Thermodynamic, Hydrothermal
Research subject Meteorology; Oceanography
IdentifiersURN: urn:nbn:se:su:diva-96549DOI: 10.1175/JAS-D-13-0173.1ISI: 000331927800004OAI: oai:DiVA.org:su-96549DiVA: diva2:677063