Brief description about the Fu-Liou-Gu radiation scheme

 

The Fu-Liou-Gu radiation scheme (Gu et al., 2010; Gu et al., 2011) implemented in the WRF is based on the Fu-Liou scheme (Fu and Liou, 1992, 1993). This scheme uses a combination of the d-4-stream approximation for the solar flux (Liou et al. 1988) and the d-2/4-stream approximation for the infrared flux to achieve a balance between accuracy and computational efficiency (Fu et al. 1997). The incorporation of nongray gaseous absorption in multiple-scattering atmospheres is based on the correlated k-distribution method developed by Fu and Liou (1992). The solar and IR spectra are divided into 6 and 12 bands, respectively, according to the location of absorption bands. In addition to the principal absorbing gases listed in Fu and Liou (1993), we recently included absorption by water vapor continuum and a number of minor absorbers in the solar spectrum, including CH4, N2O, NO2, O3, CO, SO2, O2-O2, and N2-O2. This led to an additional absorption of solar flux in a clear atmosphere on the order of 1-3 W/m2 depending on the solar zenith angle and the amount of water vapor employed in the calculations (Zhang et al., 2005). Single-scattering properties for ice clouds, including the spectral extinction coefficient, the single-scattering albedo, and the asymmetry factor, are parameterized in terms of ice water content and mean effective particle size with fitting coefficients determined from the basic scattering and absorption database provided in Yang et al. (2000) for solar spectrum and Yang et al. (2005) for thermal infrared spectrum, in which a cirrus cloud is assumed to have mixed habits. For water clouds, the single-scattering properties are parameterized in terms of the liquid water content and mean effective radius by interpolation using the mean single-scattering properties of eight water cloud types for each spectral band. This scheme also includes the parameterization for calculating the direct radiative effects of 18 types of aerosol (Gu et al. 2006), including maritime, continental, urban, five different sizes of mineral dust, insoluble, water soluble, soot (black carbon), sea salt in two modes (accumulation mode and coarse mode), mineral dust in four different modes (nucleation mode, accumulation mode, coarse mode, and transported mode). The radiative properties of aerosols, including the extinction coefficient, single-scattering albedo and asymmetry factor, are determined by their composition, shape and size distribution and are parameterized using the Optical Properties of Aerosols and Clouds (OPAC) database (dÕAlmeida et al. 1991; Tegen and Fung 1995; Tegen and Lacis 1996; Hess et al. 1998).

 

 

Major Reference:

 

Gu, Y., Liou, K. N., Ou, S. C., and Fovell, R.: Cirrus cloud simulations using WRF with improved radiation parameterization and increased vertical resolution, J. Geophys. Res., 116, D06119, doi:10.1029/2010JD014574, 2011.

 

Other references for the Fu-Liou-Gu scheme:

 

dÕAlmeida, G. A., P. Koepke, and E. P. Shettle, 1991: Atmospheric aerosols - global climatology and radiative characteristics. A. Deepak Publishing, Hampton, Virginia, 561 pp.

Fu, Q., and K. N. Liou, 1992: On the correlated k-distribution method for radiative transfer in nonhomogeneous atmospheres, J. Atmos. Sci., 49, 2139-2156.

Fu, Q., K. N. Liou, M. C. Cribb, T. P. Charlock, and A. Grossman, 1997: Multiple scattering parameterization in thermal infrared radiative transfer. J. Atmos. Sci., 54, 2799-2812.

Fu, Q., Liou, K. N., Cribb, M. C., Charlock, T. P., and Grossman, A.: Multiple scattering parameterization in thermal infrared radiative transfer, J. Atmos. Sci., 54, 2799-2812, 1997.

Gu, Y., K. N. Liou, Y. Xue, C. R. Mechoso, W. Li, and Y. Luo, 2006: Climatic effects of different aerosol types in China simulated by the UCLA general circulation model. J. Geophys. Res., 111, D15201, doi:10.1029/2005JD006312.

Gu, Y., Liou, K. N., Chen, W., and Liao, H.: Direct climate effect of black carbon in China and its impact on dust storm, J. Geophys. Res., 115, D00K14, doi:10.1029/2009JD013427, 2010.

Liou, K. N., Q. Fu., and T. P. Ackerman, 1988: A simple formulation of the delta-four-stream approximation for radiative transfer parameterizations. J. Atmos. Sci., 45, 1940-1947.

Tegen, I., and I. Fung, 1995: Contribution to the atmospheric mineral aerosol load from land surface modification. J. Geophys. Res., 100, 18707-18726.

Tegen, I., and A. A. Lacis, 1996: Modeling of particle size distribution and its influence on the radiative properties of mineral dust aerosol. J. Geophys. Res., 101, 19237-19244.

Hess, M., P. Koepke, and I. Schult, 1998: Optical properties of aerosols and clouds: The software package OPAC. Bull. Am. Met. Soc., 79, 831-844.

Yang, P., Liou, K. N., Wyser, K., and Mtichell, D.: Parameterization of the scattering and absorption properties of individual ice crystals, J. Geophys. Res., 105, 4699–4718, 2000.

Yang, P., Wei, H., Huang, H.-L., Baum, B. A., Hu, Y. X., Kattawar, G. W., Mishchenko, M. I., and Fu, Q.: Scattering and absorption property database for nonspherical ice particles in the near- through far-infrared spectral region, Appl. Optics, 44, 5512-5523, 2005.

Zhang, F., Zeng, Q., Gu, Y., and Liou, K. N.: Parameterization of the absorption of H2O continuum, CO2, O2, and other trace gases in the Fu-Liou solar radiation program, Advances in Atmos. Sci., 22, 545-558, 2005.