An idealized radiative transfer scheme for use in a mechanistic general circulation model from the surface up to the mesopause region

2011 ◽  
Vol 112 (9) ◽  
pp. 1460-1478 ◽  
Author(s):  
Rahel Knöpfel ◽  
Erich Becker
Keyword(s):  
Radiative Transfer ◽  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Transfer Scheme ◽  
Mesopause Region

scholarly journals Solar-locked and geographical atmospheric structures inferred from a Venus general circulation model with radiative transfer

Icarus ◽  
2019 ◽  
Vol 321 ◽  
pp. 232-250 ◽  
Author(s):  
Masaru Yamamoto ◽  
Kohei Ikeda ◽  
Masaaki Takahashi ◽  
Takeshi Horinouchi
Keyword(s):  
Radiative Transfer ◽  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model

scholarly journals The effect of metallicity on the atmospheres of exoplanets with fully coupled 3D hydrodynamics, equilibrium chemistry, and radiative transfer

2018 ◽  
Vol 612 ◽  
pp. A105 ◽  
Author(s):  
B. Drummond ◽  
N. J. Mayne ◽  
I. Baraffe ◽  
P. Tremblin ◽  
J. Manners ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
General Circulation ◽  
Thermal Structure ◽  
Equations Of Motion ◽  
Circulation Model ◽  
Grid Cell ◽  
Phase Curve ◽  
Heating Rates ◽  
Transfer Scheme ◽  
Energy Minimisation

In this work, we have performed a series of simulations of the atmosphere of GJ 1214b assuming different metallicities using the Met Office Unified Model (UM). The UM is a general circulation model (GCM) that solves the deep, non-hydrostatic equations of motion and uses a flexible and accurate radiative transfer scheme, based on the two-stream and correlated-k approximations, to calculate the heating rates. In this work we consistently couple a well-tested Gibbs energy minimisation scheme to solve for the chemical equilibrium abundances locally in each grid cell for a general set of elemental abundances, further improving the flexibility and accuracy of the model. As the metallicity of the atmosphere is increased we find significant changes in the dynamical and thermal structure, with subsequent implications for the simulated phase curve. The trends that we find are qualitatively consistent with previous works, though with quantitative differences. We investigate in detail the effect of increasing the metallicity by splitting the mechanism into constituents, involving the mean molecular weight, the heat capacity and the opacities. We find the opacity effect to be the dominant mechanism in altering the circulation and thermal structure. This result highlights the importance of accurately computing the opacities and radiative transfer in 3D GCMs.

scholarly journals Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

2007 ◽  
Vol 7 (10) ◽  
pp. 2503-2515 ◽  
Author(s):  
C. Cagnazzo ◽  
E. Manzini ◽  
M. A. Giorgetta ◽  
P. M. De F. Forster ◽  
J. J. Morcrette
Keyword(s):  
Radiative Transfer ◽  
General Circulation Model ◽  
Spectral Resolution ◽  
General Circulation ◽  
Circulation Model ◽  
Shortwave Radiation ◽  
Transfer Model ◽  
Ozone Absorption ◽  
Zonal Winds ◽  
Radiation Scheme

Abstract. In order to improve the representation of ozone absorption in the stratosphere of the MAECHAM5 general circulation model, the spectral resolution of the shortwave radiation parameterization used in the model has been increased from 4 to 6 bands. Two 20-years simulations with the general circulation model have been performed, one with the standard and the other with the newly introduced parameterization respectively, to evaluate the temperature and dynamical changes arising from the two different representations of the shortwave radiative transfer. In the simulation with the increased spectral resolution in the radiation parameterization, a significant warming of almost the entire model domain is reported. At the summer stratopause the temperature increase is about 6 K and alleviates the cold bias present in the model when the standard radiation scheme is used. These general circulation model results are consistent both with previous validation of the radiation scheme and with the offline clear-sky comparison performed in the current work with a discrete ordinate 4 stream scattering line by line radiative transfer model. The offline validation shows a substantial reduction of the daily averaged shortwave heating rate bias (1–2 K/day cooling) that occurs for the standard radiation parameterization in the upper stratosphere, present under a range of atmospheric conditions. Therefore, the 6 band shortwave radiation parameterization is considered to be better suited for the representation of the ozone absorption in the stratosphere than the 4 band parameterization. Concerning the dynamical response in the general circulation model, it is found that the reported warming at the summer stratopause induces stronger zonal mean zonal winds in the middle atmosphere. These stronger zonal mean zonal winds thereafter appear to produce a dynamical feedback that results in a dynamical warming (cooling) of the polar winter (summer) mesosphere, caused by an increased downward (upward) circulation in the winter (summer) hemisphere. In addition, the comparison of the two simulations performed with the general circulation model shows that the increase in the spectral resolution of the shortwave radiation and the associated changes in the cloud optical properties result in a warming (0.5–1 K) and moistening (3%–12%) of the upper tropical troposphere. By comparing these modeled differences with previous works, it appears that the reported changes in the solar radiation scheme contribute to improve the model mean temperature also in the troposphere.

scholarly journals Robustness of neural network emulations of radiative transfer parameterizations in a state-of-the-art general circulation model

2021 ◽  
Vol 14 (12) ◽  
pp. 7425-7437 ◽  
Author(s):  
Alexei Belochitski ◽  
Vladimir Krasnopolsky
Keyword(s):  
Neural Network ◽  
Radiative Transfer ◽  
General Circulation Model ◽  
Network Architecture ◽  
General Circulation ◽  
State Of The Art ◽  
Circulation Model ◽  
Physically Based ◽  
The Stability ◽  
Model Components

Abstract. The ability of machine-learning-based (ML-based) model components to generalize to the previously unseen inputs and its impact on the stability of the models that use these components have been receiving a lot of recent attention, especially in the context of ML-based parameterizations. At the same time, ML-based emulators of existing physically based parameterizations can be stable, accurate, and fast when used in the model they were specifically designed for. In this work we show that shallow-neural-network-based emulators of radiative transfer parameterizations developed almost a decade ago for a state-of-the-art general circulation model (GCM) are robust with respect to the substantial structural and parametric change in the host model: when used in two 7-month-long experiments with a new GCM, they remain stable and generate realistic output. We concentrate on the stability aspect of the emulators' performance and discuss features of neural network architecture and training set design potentially contributing to the robustness of ML-based model components.

Sign in / Sign up

Export Citation Format

Share Document