Cloud-Resolving Model Simulations over the ARM SGP

Abstract

This study aims to combine the cloud-resolving model (CRM) simulations with the Department of Energy’s Atmospheric Radiation Measurement Program (ARM) observations to provide long-term comprehensive and physically consistent data that facilitate quantifying the effects of subgrid cloud–radiation interactions and ultimately to develop physically based parameterization of these interactions in general circulation models. The CRM is applied here to simulate the midlatitude cloud systems observed at the ARM southern Great Plains (SGP) site during the 1997 intensive observation period. As in the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE), the CRM-simulated ensemble mean quantities such as cloud liquid water, cloud fraction, precipitation, and radiative fluxes are generally in line with the surface measurements, satellite, and radar retrievals. The CRM differences from the ARM estimates, when averaged over the entire period, are less than 5 W m−2 in both longwave and shortwave radiative fluxes at the top of the atmosphere and surface. Because of the different large-scale forcing and surface heat fluxes in ARM and TOGA COARE, the CRM produces different cloud distributions over the midlatitude continent and tropical ocean. However, diagnostic analyses show that the subgrid cloud variability has similar impact on the domain-averaged radiative fluxes and heating rates in ARM as in TOGA COARE.

Large‐Scale Circulation Environment and Microphysical Characteristics of the Cloud Systems Over the Tibetan Plateau in Boreal Summer

“…Cloud depth can reflect the cloud precipitation potential capacity and it is shown in Figure 7c. PCC over the TP has a depth in the range of 6–9 km, which is thinner than DCs over the American Southern Great Plains and the tropical ocean (e.g., Wu et al, 2007). The ETP PCC usually has a depth thinner than 8 km in May and June (Figure 7a) and hits its maximum depth in July.…”

Quantitative Assessment of Diurnal Variation of Tropical Convection Simulated by a Global Nonhydrostatic Model without Cumulus Parameterization

“…Noda et al (2010) addressed this issue by suggesting that the present turbulent scheme should incorporate the interaction between resolvable and SGS motions. Previous numerical studies that are conducted based on field observations also show the importance of such small-scale clouds and turbulent processes for simulating tropical convective systems (e.g., Grabowski et al 1998;Xu and Randall 1996;Donner et al 1999;Wu et al 2007). For improving a GCM (or at least every so-called cloud-resolving model with a horizontal grid size .100 m), numerical modelers need to consider a trial installation of a parameterization scheme of shallow convection developed based on state-of-the-art knowledge (e.g., Bretherton et al 2004;Bretherton and Park 2009).…”

A simple model of convection with memory

“…Although the source of COOL is not specified, its value is chosen to be representative of typical atmospheric cooling rates in the tropics. Thus, a constant cooling of 2°C d −1 has been imposed, typical of values that have been found in observational studies [e.g., Wu et al , 2007; Xu et al , 2002] and used in idealized cloud‐resolving model studies [e.g., Tompkins and Craig , 1998; Stirling and Petch , 2004]. (Note that the regimes to be discussed in section 3.1 have also been identified for other choices of the cooling rate.…”