Impact of Precipitating Ice Hydrometeors on Longwave Radiative Effect Estimated by a Global Cloud‐System Resolving Model

Abstract

Satellite observation and general circulation model (GCM) studies suggest that precipitating ice makes nonnegligible contributions to the radiation balance of the Earth. However, in most GCMs, precipitating ice is diagnosed and its radiative effects are not taken into account. Here we examine the longwave radiative impact of precipitating ice using a global nonhydrostatic atmospheric model with a double‐moment cloud microphysics scheme. An off‐line radiation model is employed to determine cloud radiative effects according to the amount and altitude of each type of ice hydrometeor. Results show that the snow radiative effect reaches 2 W m−2 in the tropics, which is about half the value estimated by previous studies. This effect is strongly dependent on the vertical separation of ice categories and is partially generated by differences in terminal velocities, which are not represented in GCMs with diagnostic precipitating ice. Results from sensitivity experiments that artificially change the categories and altitudes of precipitating ice show that the simulated longwave heating profile and longwave radiation field are sensitive to the treatment of precipitating ice in models. This study emphasizes the importance of incorporating appropriate treatments for the radiative effects of precipitating ice in cloud and radiation schemes in GCMs in order to capture the cloud radiative effects of upper level clouds.

Prognostic Precipitation in the MIROC6‐SPRINTARS GCM: Description and Evaluation Against Satellite Observations

“…The differences in global mean OLR and OSR between the ON/SnwRad and OFF/SnwRad experiments are significant, 6.4 and 5.1 W/m 2 in absolute values, respectively (i.e., ΔF net = 1.3 W/m 2 ). These values are larger than those previously estimated by and Chen et al (2018), because MIROC6 PROG has more SWP than the models used in previous studies. Given that the real atmosphere has more TIWP compared to that in models (Figure 1c), the radiative impacts should be more significant.…”

“…Sets of simulations were performed using the PROG scheme both with and without the snow radiation effect, as summarized in Table 2. Although there has been some similar research recently (e.g., Chen et al, 2018;Li et al, 2016), our findings related to the impact of the snow radiative effect on model performance are expected to make a valuable contribution because most GCMs still ignore the radiative effect of snow. Figure 10 illustrates outgoing longwave radiation (OLR) and shows that both the DIAG and PROG schemes are in good agreement with the CERES satellite observations.…”

The non-hydrostatic global atmospheric model for CMIP6 HighResMIP simulations (NICAM16-S): Experimental design, model description, and sensitivity experiments

“…The RADPARA database was then compiled as a lookup table of the effective radii from 1 μm to 1 mm to cover size range of most of the hydrometeors in global simulations (Seiki et al, 2014). The effects of precipitating hydrometeors on the radiation budget are detectable specifically over the intertropical convergence zone (ITCZ) and storm-track region (e.g., Chen et al, 2018;Li et al, 2014Li et al, , 2016Michibata et al, 2019;Waliser et al, 2011). The revised RADPARA database was evaluated in depth by comparing it with balloon-borne sonde observations in a midlatitude cirrus case (Seiki et al, 2014), and its effectiveness for global simulations was evaluated in several studies (Satoh et al, 2018;Seiki et al, 2015aSeiki et al, , 2015b).…”

Characteristics of Ice Clouds Over Mountain Regions Detected by CALIPSO and CloudSat Satellite Observations

“…The IWC and the ice effective radius (REI) have been widely used for model evaluation (e.g., Chen et al, ; Chen et al, ; Seiki, Kodama, Satoh, et al, ; Waliser et al, ). van Diedenhoven et al () developed an advanced technique to analyze the REI vertical profile within clouds and indicated the mechanisms for vertical REI variability in convective clouds.…”