scholarly journals Towards a better representation of the solar cycle in general circulation models

2007 ◽  
Vol 7 (1) ◽  
pp. 45-64
Author(s):  
K. M. Nissen ◽  
K. Matthes ◽  
U. Langematz ◽  
B. Mayer
Keyword(s):  
Solar Cycle ◽  
High Resolution ◽  
Heating Rate ◽  
General Circulation ◽  
General Circulation Models ◽  
Short Wave ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Radiation Scheme ◽  
Good Agreement

Abstract. It is shown that a high-resolution short-wave (SW) heating rate parameterization is necessary to simulate solar cycle variations in atmospheric models. The improved Freie Universität Berlin (FUB) high-resolution radiation scheme (FUBRad) is introduced and compared to the 4-band ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle and a temperature response that is in good agreement with observations. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. Comparison of the total short-wave heating rates under moderate solar conditions shows good agreement between FUBRad, FB and libRadtran up to 80 km indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

scholarly journals Towards a better representation of the solar cycle in general circulation models

2007 ◽  
Vol 7 (20) ◽  
pp. 5391-5400 ◽  
Author(s):  
K. M. Nissen ◽  
K. Matthes ◽  
U. Langematz ◽  
B. Mayer
Keyword(s):  
Solar Cycle ◽  
Heating Rate ◽  
General Circulation ◽  
Temperature Response ◽  
General Circulation Models ◽  
Short Wave ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Heating Rates ◽  
Radiation Scheme

Abstract. We introduce the improved Freie Universität Berlin (FUB) high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction) of the solar SW heating rate signal by about 20%. The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal. Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60–70 km) indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

GPU-Accelerated Longwave Radiation Scheme of the Rapid Radiative Transfer Model for General Circulation Models (RRTMG)

2014 ◽  
Vol 7 (8) ◽  
pp. 3660-3667 ◽  
Author(s):  
Erik Price ◽  
Jarno Mielikainen ◽  
Melin Huang ◽  
Bormin Huang ◽  
Hung-Lung Allen Huang ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
General Circulation ◽  
Longwave Radiation ◽  
General Circulation Models ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Radiation Scheme

scholarly journals Improvement of the Simulation of Cloud Longwave Scattering in Broadband Radiative Transfer Models

2018 ◽  
Vol 75 (7) ◽  
pp. 2217-2233 ◽  
Author(s):  
Guanglin Tang ◽  
Ping Yang ◽  
George W. Kattawar ◽  
Xianglei Huang ◽  
Eli J. Mlawer ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Multiple Scattering ◽  
General Circulation ◽  
General Circulation Models ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Discrete Ordinate ◽  
Wide Range ◽  
Scaling Methods ◽  
Computational Errors

Abstract Cloud longwave scattering is generally neglected in general circulation models (GCMs), but it plays a significant and highly uncertain role in the atmospheric energy budget as demonstrated in recent studies. To reduce the errors caused by neglecting cloud longwave scattering, two new radiance adjustment methods are developed that retain the computational efficiency of broadband radiative transfer simulations. In particular, two existing scaling methods and the two new adjustment methods are implemented in the Rapid Radiative Transfer Model (RRTM). The results are then compared with those based on the Discrete Ordinate Radiative Transfer model (DISORT) that explicitly accounts for multiple scattering by clouds. The two scaling methods are shown to improve the accuracy of radiative transfer simulations for optically thin clouds but not effectively for optically thick clouds. However, the adjustment methods reduce computational errors over a wide range, from optically thin to thick clouds. With the adjustment methods, the errors resulting from neglecting cloud longwave scattering are reduced to less than 2 W m−2 for the upward irradiance at the top of the atmosphere and less than 0.5 W m−2 for the surface downward irradiance. The adjustment schemes prove to be more accurate and efficient than a four-stream approximation that explicitly accounts for multiple scattering. The neglect of cloud longwave scattering results in an underestimate of the surface downward irradiance (cooling effect), but the errors are almost eliminated by the adjustment methods (warming effect).

scholarly journals Evaluating and improving the treatment of gases in radiation schemes: the Correlated K-Distribution Model Intercomparison Project (CKDMIP)

2020 ◽  
Author(s):  
Robin J. Hogan ◽  
Marco Matricardi
Keyword(s):  
General Circulation ◽  
Computational Cost ◽  
General Circulation Models ◽  
Gas Absorption ◽  
Distribution Model ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. Most radiation schemes in weather and climate models use the 'correlated k-distribution' (CKD) method to treat gas absorption, which approximates a broadband spectral integration by N pseudo-monochromatic calculations. Larger N means more accuracy and a wider range of gas concentrations can be simulated, but at greater computational cost. Unfortunately, the tools to perform this efficiency-accuracy trade-off (e.g., to generate separate CKD models for applications such as short-range weather forecasting to climate modelling) are unavailable to the vast majority of users of radiation schemes. This paper describes the experimental protocol for the Correlated K-Distribution Model Intercomparison Project (CKDMIP), whose purpose is to use benchmark line-by-line calculations: (1) to evaluate the accuracy of existing CKD models, (2) to explore how accuracy varies with N for CKD models submitted by CKDMIP participants, (3) to understand how different choices in way that CKD models are generated affects their accuracy for the same N, and (4) to generate freely available datasets and software facilitating the development of new gas-optics tools. The datasets consist of the high-resolution longwave and shortwave absorption spectra of nine gases for a range of atmospheric conditions, realistic and idealized. Thirty-four concentration scenarios for the well-mixed greenhouse gases are proposed to test CKD models from palaeo- to future-climate conditions. We demonstrate the strengths of the protocol in this paper by using it to evaluate the widely-used Rapid Radiative Transfer Model for General Circulation Models (RRTMG).

scholarly journals A systematic study of CO2 planetary atmospheres and their link to the stellar environment

2020 ◽  
Vol 496 (4) ◽  
pp. 5350-5359 ◽  
Author(s):  
A Petralia ◽  
E Alei ◽  
G Aresu ◽  
D Locci ◽  
C Cecchi-Pestellini ◽  
...  
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Ocean Dynamics ◽  
Atmospheric Composition ◽  
Radiative Transfer Model ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Milky Way Galaxy ◽  
Origin And Evolution ◽  
Large Numbers

ABSTRACT The Milky Way Galaxy is literally teeming with exoplanets; thousands of planets have been discovered, with thousands more planet candidates identified. Terrestrial-like planets are quite common around other stars, and are expected to be detected in large numbers in the future. Such planets are the primary targets in the search for potentially habitable conditions outside the Solar system. Determining the atmospheric composition of exoplanets is mandatory to understand their origin and evolution, as atmospheric processes play crucial roles in many aspects of planetary architecture. In this work we construct and exploit a 1D radiative transfer model based on the discrete-ordinates method in plane-parallel geometry. Radiative results are linked to a convective flux that redistributes energy at any altitude producing atmospheric profiles in radiative–convective equilibrium. The model has been applied to a large number (6250) of closely dry synthetic CO2 atmospheres, and the resulting pressure and thermal profiles have been interpreted in terms of parameter variability. Although less accurate than 3D general circulation models, not properly accounting for e.g. clouds and atmospheric and ocean dynamics, 1D descriptions are computationally inexpensive and retain significant value by allowing multidimensional parameter sweeps with relative ease.

scholarly journals A Novel GPU-Based Acceleration Algorithm for a Longwave Radiative Transfer Model

2020 ◽  
Vol 10 (2) ◽  
pp. 649 ◽  
Author(s):  
Yuzhu Wang ◽  
Yuan Zhao ◽  
Jinrong Jiang ◽  
He Zhang
Keyword(s):  
Radiative Transfer ◽  
General Circulation ◽  
Large Scale ◽  
General Circulation Models ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Processing Unit ◽  
Heating Rates ◽  
Area Of Interest ◽  
Intel Xeon

Graphics processing unit (GPU)-based computing for climate system models is a longstanding research area of interest. The rapid radiative transfer model for general circulation models (RRTMG), a popular atmospheric radiative transfer model, can calculate atmospheric radiative fluxes and heating rates. However, the RRTMG has a high calculation time, so it is urgent to study its GPU-based efficient acceleration algorithm to enable large-scale and long-term climatic simulations. To improve the calculative efficiency of radiation transfer, this paper proposes a GPU-based acceleration algorithm for the RRTMG longwave radiation scheme (RRTMG_LW). The algorithm concept is accelerating the RRTMG_LW in the g- p o i n t dimension. After implementing the algorithm in CUDA Fortran, the G-RRTMG_LW was developed. The experimental results indicated that the algorithm was effective. In the case without I/O transfer, the G-RRTMG_LW on one K40 GPU obtained a speedup of 30.98× over the baseline performance on one single Intel Xeon E5-2680 CPU core. When compared to its counterpart running on 10 CPU cores of an Intel Xeon E5-2680 v2, the G-RRTMG_LW on one K20 GPU in the case without I/O transfer achieved a speedup of 2.35×.

scholarly journals A Spectral Data Compression (SDCOMP) Radiative Transfer Model for High-Spectral-Resolution Radiation Simulations

2020 ◽  
Vol 77 (6) ◽  
pp. 2055-2066 ◽  
Author(s):  
Chao Liu ◽  
Bin Yao ◽  
Vijay Natraj ◽  
Pushkar Kopparla ◽  
Fuzhong Weng ◽  
...  
Keyword(s):  
Optical Property ◽  
Radiative Transfer ◽  
Data Compression ◽  
Spectral Data ◽  
Spectral Resolution ◽  
General Circulation ◽  
General Circulation Models ◽  
High Spectral Resolution ◽  
Radiative Transfer Model ◽  
Transfer Model

Abstract With the increasing use of satellite and ground-based high-spectral-resolution (HSR) measurements for weather and climate applications, accurate and efficient radiative transfer (RT) models have become essential for accurate atmospheric retrievals, for instrument calibration, and to provide benchmark RT solutions. This study develops a spectral data compression (SDCOMP) RT model to simulate HSR radiances in both solar and infrared spectral regions. The SDCOMP approach “compresses” the spectral data in the optical property and radiance domains, utilizing principal component analysis (PCA) twice to alleviate the computational burden. First, an optical-property-based PCA is performed for a given atmospheric scenario (atmospheric, trace gas, and aerosol profiles) to simulate relatively low-spectral-resolution radiances at a small number of representative wavelengths. Second, by using precalculated principal components from an accurate radiance dataset computed for a large number of atmospheric scenarios, a radiance-based PCA is carried out to extend the low-spectral-resolution results to desired HSR results at all wavelengths. This procedure ensures both that individual monochromatic RT calculations are efficiently performed and that the number of such computations is optimized. SDCOMP is approximately three orders of magnitude faster than numerically exact RT calculations. The resulting monochromatic radiance has relative errors less than 0.2% in the solar region and brightness temperature differences less than 0.1 K for over 95% of the cases in the infrared region. The efficiency and accuracy of SDCOMP not only make it useful for analysis of HSR measurements, but also hint at the potential for utilizing this model to perform RT simulations in mesoscale numerical weather and general circulation models.

scholarly journals Radiative Fluxes in the ECHAM5 General Circulation Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3792-3809 ◽  
Author(s):  
Martin Wild ◽  
Erich Roeckner
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Circulation Model ◽  
Shortwave Radiation ◽  
Radiative Transfer Model ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Transfer Model ◽  
Radiative Fluxes ◽  
Good Agreement

Abstract Radiative fluxes in the ECHAM5 general circulation model (GCM) are evaluated using both surface and satellite-based observations. The fluxes at the top of the atmosphere (TOA) are generally in good agreement with the satellite data. Larger deviations in simulated cloud forcing are found especially at lower latitudes where the shortwave component within the intertropical convergence zone is overestimated during boreal summer and underestimated in the marine stratocumulus regimes, especially during boreal winter. At the surface the biases in the radiative fluxes are significantly smaller than in earlier versions of the same model and in other GCMs. The shortwave clear-sky fluxes are shown to be in good agreement with newly derived observational estimates. Compared to the preceding model version, ECHAM4, the spurious absorption of solar radiation in the cloudy atmosphere disappears due to the higher resolution in the near-infrared bands of the shortwave radiation code. This reduces the biases with respect to collocated surface and TOA observations. It is illustrated that remaining biases in atmospheric absorption may be related to the crude aerosol climatology, which does not account for high loadings of absorbing aerosol such as from biomass burning, whereas the biases disappear in areas and seasons where aerosol effects are less important. In the longwave, the introduction of the Rapid Radiative Transfer Model (RRTM) radiation code leads to an increase in the longwave downward flux at the surface at high latitudes, thereby reducing biases typically found in GCMs. The considerable skill in the simulation of the fluxes at the earth’s surface underlines the suitability of ECHAM5 as an atmospheric component of an integrated earth system model.

scholarly journals Using a GPU to Accelerate a Longwave Radiative Transfer Model with Efficient CUDA-Based Methods

2019 ◽  
Vol 9 (19) ◽  
pp. 4039 ◽  
Author(s):  
Yuzhu Wang ◽  
Yuan Zhao ◽  
Wei Li ◽  
Jinrong Jiang ◽  
Xiaohui Ji ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Domain Decomposition ◽  
General Circulation ◽  
General Circulation Models ◽  
Radiative Transfer Model ◽  
Wave Radiation ◽  
Transfer Model ◽  
Processing Unit ◽  
Radiation Physics ◽  
Dimensional Domain

Climatic simulations rely heavily on high-performance computing. As one of the atmospheric radiative transfer models, the rapid radiative transfer model for general circulation models (RRTMG) is used to calculate the radiative transfer of electromagnetic radiation through a planetary atmosphere. Radiation physics is one of the most time-consuming physical processes, so the RRTMG presents large-scale and long-term simulation challenges to the development of efficient parallel algorithms that fit well into multicore clusters. This paper presents a method for improving the calculative efficiency of radiation physics, an RRTMG long-wave radiation scheme (RRTMG_LW) that is accelerated on a graphics processing unit (GPU). First, a GPU-based acceleration algorithm with one-dimensional domain decomposition is proposed. Then, a second acceleration algorithm with two-dimensional domain decomposition is presented. After the two algorithms were implemented in Compute Unified Device Architecture (CUDA) Fortran, a GPU version of the RRTMG_LW, namely G-RRTMG_LW, was developed. Results demonstrated that the proposed acceleration algorithms were effective and that the G-RRTMG_LW achieved a significant speedup. In the case without I/O transfer, the 2-D G-RRTMG_LW on one K40 GPU obtained a speed increase of 18.52× over the baseline performance on a single Intel Xeon E5-2680 CPU core.

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