Extension of a Multisensor Satellite Radiance-Based Evaluation for Cloud System Resolving Models

Abstract

As an alternative approach to previous multisensor satellite evaluations for cloud system resolving models (CSRMs), a technique for precipitation clouds over the ocean of CSRMs is presented using combined infrared and microwave channels. This method quantitatively analyzes precipitation clouds using cloud-top temperatures and ice scatterings from infrared 11 µm and high frequency microwave (89.0 GHz) brightness temperatures (TBs). The TB threshold at low frequencies (18.7 GHz) is used to identify precipitation regions. This method extends a previous approach based on tropical rainfall measuring mission (TRMM) precipitation radar which uses a narrow coverage, by incorporating a wide passive microwave sensor swath and ice cloud sensitivity.The numerical results of the non-hydrostatic icosahedral atmospheric model, NICAM, with two cloud microphysics schemes were evaluated over the tropical open ocean using this method. The scattering intensities in both simulations at 89.0 GHz were different due to the parameterizations of the snow and graupel size distributions. A bimodal snow size distribution improved the TB underestimation at 89.0 GHz. These results exhibited similar structures to the joint histograms of cloud-top temperatures and precipitation-top heights generated using the previous method; the frequencies of overestimated scattering intensities in this study and the frequencies of high precipitation-top heights above 12 km in the previous study. It was observed that the change in the snow size distribution in the cloud microphysics scheme can lead to better agreements of simulated TBs at 89.0 GHz. Furthermore, we investigated the impacts of nonspherical snow assumptions using a satellite simulator. The effect of a nonspherical snow shape in the radiative transfer model caused a smaller change in TBs at 89.0 GHz compared to the difference between the TBs of the two simulations without nonspherical assumptions.

The Nonhydrostatic ICosahedral Atmospheric Model for CMIP6 HighResMIP simulations (NICAM16-S): experimental design, model description, and impacts of model updates

“…Table 4 gives a summary of the physics schemes used in NICAM16-S and NICAM.12. A single-moment bulk cloud microphysics scheme, NICAM Single-Moment Water 6 (NSW6), that solves mass concentrations for six water categories -vapor, cloud water, cloud ice, rain, snow, and graupel Roh and Satoh, 2014;Roh et al, 2017) -is used instead of a combination of convection and large-scale condensation schemes. While most climate models use convection and large-scale condensation schemes, even for a mesh size around 14 km, we used the cloud microphysics scheme to represent interactions between clouds and circulation in an explicit way.…”

“…2.2 and Table 2, a series of shortterm sensitivity experiments were performed to monitor the impacts of several model updates on the simulated climatology. Figure 5 Roh and Satoh, 2014;Roh et al, 2017) NSW6 Kodama et al, 2012) Cumulus convection and largescale condensation Not used Not used Radiation mstrnX (Sekiguchi and Nakajima, 2008), updated radiation table (Takata et al, 2003) with wetland scheme (Nitta et al, 2017) MATSIRO (Takata et al, 2003) Ocean surface flux Bulk surface scheme (Louis, 1979); surface roughness is evaluated following Fairall et al (2003) and Moon et al (2007)…”

“…Also, some significant climate biases have been identified in the simulation (Kodama et al, 2015), and great effort has been devoted to improving the model for better performance of the simulated climate in a physically consistent manner. Major updates from NICAM.12 to NICAM.16, a stable version of NICAM released in 2017, included the cloud microphysics scheme based on a comparison with the Tropical Rainfall Measuring Mission (TRMM) satellite observations (Roh and Satoh, 2014;Roh et al, 2017), introduction of a wetland scheme in the land surface model (Nitta et al, 2017), implementation of the coupling between cloud microphysics and radiation that considers the nonsphericity of ice particles , and introduction of a subgrid-scale orographic gravity wave drag scheme. In addition, some parameters related to the processes of surface albedo and sea ice have been revised.…”

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

“…Finally, they achieved successful reproduction of the vertical structures of shallow, congestus, and deep convective clouds over the tropics, comparing to TRMM and CloudSat satellite observations. They also used microwave satellite observations to evaluate the simulated results (Roh and Satoh, 2018); hence, improvements in tropical cloud systems with the revised scheme are robust in terms of optical signals (see the original papers for more details).…”

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

“…Their results imply the importance of reliable ice microphysics modeling and the evaluation of ice clouds using satellite observations. Recently, detailed ice cloud microphysical models have been developed and tested to attain more realistic global ice cloud simulations (e.g., Eidhammer et al, ; Gettelman et al, ; Hashino et al, , ; Lang et al, ; Lang et al, ; Morrison & Gettelman, ; Roh & Satoh, , ; Roh et al, ; Seiki et al, ; Seiki, Kodama, Noda, et al, ; Seiki et al, ). Satellite observations enable the evaluation of ice microphysics in various cases and perspectives.…”