12:00 PM - 12:15 PM
[AAS03-11] Improvements of the Broadband Radiative Transfer Model “MstrnX”
Keywords:Radiative transfer model, gas absorption process
There is a great demand for an accurate yet rapid radiation transfer scheme for global climate models. The broadband radiative transfer model "mstrnX" (Sekiguchi and Nakajima, 2008) was developed by Atmosphere and Ocean Research Institute (AORI). This model has been implemented in several Japanese global and regional climate models, for example, MIROC (the Model for Interdisciplinary Research on Climate) (Tatebe et al., 2019), NICAM (Non-hydrostatic Icosahedral Atmospheric Model) (Satoh et al., 2008), etc. MstrnX is adopted the optimization method to decrease the number of integration points for correlated k-distribution, and it makes possible rapid calculations. However, this model underestimates shortwave absorption (Smith et al., 2020) and overestimates longwave radiation in the case of quadrupled carbon dioxide concentrations (Pincus et al., 2015). The former mainly depends on the update of the database, and the latter comes from an optimization process. In this study, we improve the gas absorption process.
The model updated by this study has participated in the Correlated K-Distribution Model Intercomparison Project (CKDMIP) (Hogan and Matricardi, 2020). The participating models have applied the same absorption line database, performed radiative transfer calculations at 50 sites in 34 scenarios, and evaluated and compared the results against the LBL model. For the solar region, the provided optical thicknesses of the respective gases at wavenumbers 250 – 50000 cm-1 and used to create the absorption tables. Absorbing gases are provided for H2O, CO2, O3, N2O, CH4, O2, N2, CFC-11 (equivalent absorption intensity), and CFC-12, but CFC-11 and 12 are not treated in the solar region. In CKDMIP, it is recommended to provide model results for multiple band numbers to check the accuracy against the band number. In this study, I applied the absorption data to our optimization algorithm and constructed absorption tables of 6, 14, 22, and 30 bands that were developed for the solar region. At the conference, we plan to show the evaluation of each of them for the CKDMIP atmosphere and the comparison with other participating models.
The model updated by this study has participated in the Correlated K-Distribution Model Intercomparison Project (CKDMIP) (Hogan and Matricardi, 2020). The participating models have applied the same absorption line database, performed radiative transfer calculations at 50 sites in 34 scenarios, and evaluated and compared the results against the LBL model. For the solar region, the provided optical thicknesses of the respective gases at wavenumbers 250 – 50000 cm-1 and used to create the absorption tables. Absorbing gases are provided for H2O, CO2, O3, N2O, CH4, O2, N2, CFC-11 (equivalent absorption intensity), and CFC-12, but CFC-11 and 12 are not treated in the solar region. In CKDMIP, it is recommended to provide model results for multiple band numbers to check the accuracy against the band number. In this study, I applied the absorption data to our optimization algorithm and constructed absorption tables of 6, 14, 22, and 30 bands that were developed for the solar region. At the conference, we plan to show the evaluation of each of them for the CKDMIP atmosphere and the comparison with other participating models.