TY - JOUR
T1 - Comparative terrestrial atmospheric circulation regimes in simplified global circulation models. Part II
T2 - Energy budgets and spectral transfers
AU - Read, Peter L.
AU - Tabataba-Vakili, Fachreddin
AU - Wang, Yixiong
AU - Augier, Pierre
AU - Lindborg, Erik
AU - Valeanu, Alexandru
AU - Young, Roland M.B.
N1 - Publisher Copyright:
© 2018 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society.
PY - 2018/10
Y1 - 2018/10
N2 - The energetics of possible global atmospheric circulation patterns in an Earth-like atmosphere are explored using a simplified global General Circulation Model (GCM) based on the University of Hamburg's Portable University Model for the Atmosphere (designated here as PUMA-S), forced by linear relaxation towards a prescribed temperature field and subject to Rayleigh surface drag and hyperdiffusive dissipation. Results from a series of simulations, obtained by varying planetary rotation rate Ω with an imposed equator-to-pole temperature difference, were analysed to determine the structure and magnitude of the heat transport and other contributions to the energy budget for the time-averaged, equilibrated flow. These show clear trends with rotation rate, with the most intense Lorenz energy cycle for an Earth-sized planet occurring with a rotation rate around half that of the present-day Earth (i.e., Ω∗ = Ω/ΩE = 1/2, where ΩE is the rotation rate of the Earth). Kinetic energy (KE) and available potential energy (APE) spectra, E K(n) and E A(n) (where n is total spherical wavenumber), also show clear trends with rotation rate, with n −3 enstrophy-dominated spectra around Ω∗ = 1 and steeper (∼n −5) slopes in the zonal mean flow with little evidence for the n −5/3 spectrum anticipated for an inverse KE cascade. Instead, both KE and APE spectra become almost flat at scales larger than the internal Rossby radius, L d, and exhibit near-equipartition at high wavenumbers. At Ω∗ < <1, the spectrum becomes dominated by KE with E K(n)∼(2–3)E A(n) at most wavenumbers and a slope that tends towards n −5/3 across most of the spectrum. Spectral flux calculations show that enstrophy and APE are almost always cascaded downscale, regardless of rotation rate. KE cascades are more complicated, however, with downscale transfers across almost all wavenumbers, dominated by horizontally divergent modes, for (Formula presented.). At higher rotation rates, transfers of KE become increasingly dominated by rotational (horizontally nondivergent) components with strong upscale transfers (dominated by eddy–zonal flow interactions) for scales larger than L d and weaker downscale transfers for scales smaller than L d.
AB - The energetics of possible global atmospheric circulation patterns in an Earth-like atmosphere are explored using a simplified global General Circulation Model (GCM) based on the University of Hamburg's Portable University Model for the Atmosphere (designated here as PUMA-S), forced by linear relaxation towards a prescribed temperature field and subject to Rayleigh surface drag and hyperdiffusive dissipation. Results from a series of simulations, obtained by varying planetary rotation rate Ω with an imposed equator-to-pole temperature difference, were analysed to determine the structure and magnitude of the heat transport and other contributions to the energy budget for the time-averaged, equilibrated flow. These show clear trends with rotation rate, with the most intense Lorenz energy cycle for an Earth-sized planet occurring with a rotation rate around half that of the present-day Earth (i.e., Ω∗ = Ω/ΩE = 1/2, where ΩE is the rotation rate of the Earth). Kinetic energy (KE) and available potential energy (APE) spectra, E K(n) and E A(n) (where n is total spherical wavenumber), also show clear trends with rotation rate, with n −3 enstrophy-dominated spectra around Ω∗ = 1 and steeper (∼n −5) slopes in the zonal mean flow with little evidence for the n −5/3 spectrum anticipated for an inverse KE cascade. Instead, both KE and APE spectra become almost flat at scales larger than the internal Rossby radius, L d, and exhibit near-equipartition at high wavenumbers. At Ω∗ < <1, the spectrum becomes dominated by KE with E K(n)∼(2–3)E A(n) at most wavenumbers and a slope that tends towards n −5/3 across most of the spectrum. Spectral flux calculations show that enstrophy and APE are almost always cascaded downscale, regardless of rotation rate. KE cascades are more complicated, however, with downscale transfers across almost all wavenumbers, dominated by horizontally divergent modes, for (Formula presented.). At higher rotation rates, transfers of KE become increasingly dominated by rotational (horizontally nondivergent) components with strong upscale transfers (dominated by eddy–zonal flow interactions) for scales larger than L d and weaker downscale transfers for scales smaller than L d.
KW - atmosphere
KW - dynamics
KW - energy budget
KW - general circulation model experiments
KW - global
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U2 - 10.1002/qj.3351
DO - 10.1002/qj.3351
M3 - Article
AN - SCOPUS:85056393752
SN - 0035-9009
VL - 144
SP - 2558
EP - 2576
JO - Quarterly Journal of the Royal Meteorological Society
JF - Quarterly Journal of the Royal Meteorological Society
IS - 717
ER -