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

2021 ◽  
Vol 14 (2) ◽  
pp. 795-820
Author(s):  
Chihiro Kodama ◽  
Tomoki Ohno ◽  
Tatsuya Seiki ◽  
Hisashi Yashiro ◽  
Akira T. Noda ◽  
...  
Keyword(s):  
Cloud Amount ◽  
Atmospheric Model ◽  
Cloud Microphysics ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Model Description ◽  
Surface Model ◽  
Model Intercomparison ◽  
Anthropogenic Aerosols ◽  
Intercomparison Project

Abstract. The Nonhydrostatic ICosahedral Atmospheric Model (NICAM), a global model with an icosahedral grid system, has been under development for nearly two decades. This paper describes NICAM16-S, the latest stable version of NICAM (NICAM.16), modified for the Coupled Model Intercomparison Project Phase 6, High Resolution Model Intercomparison Project (HighResMIP). Major updates of NICAM.12, a previous version used for climate simulations, included updates of the cloud microphysics scheme and land surface model, introduction of natural and anthropogenic aerosols and a subgrid-scale orographic gravity wave drag scheme, and improvement of the coupling between the cloud microphysics and the radiation schemes. External forcings were updated to follow the protocol of the HighResMIP. A series of short-term sensitivity experiments were performed to determine and understand the impacts of these various model updates on the simulated mean states. The NICAM16-S simulations demonstrated improvements in the ice water content, high cloud amount, surface air temperature over the Arctic region, location and strength of zonal mean subtropical jet, and shortwave radiation over Africa and South Asia. Some long-standing biases, such as the double intertropical convergence zone and smaller low cloud amount, still exist or are even worse in some cases, suggesting further necessity for understanding their mechanisms, upgrading schemes and parameter settings, and enhancing horizontal and vertical resolutions.

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

2020 ◽  
Author(s):  
Chihiro Kodama ◽  
Tomoki Ohno ◽  
Tatsuya Seiki ◽  
Hisashi Yashiro ◽  
Akita T. Noda ◽  
...  
Keyword(s):  
Atmospheric Model ◽  
Cloud Microphysics ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Model Description ◽  
Model Intercomparison ◽  
Anthropogenic Aerosols ◽  
Sensitivity Experiments ◽  
Global Atmospheric Model ◽  
Intercomparison Project

Abstract. NICAM, a nonhydrostatic global atmospheric model with an icosahedral grid system, has been developed for nearly two decades. This paper describes NICAM16-S, the latest stable version of NICAM (NICAM.16) modified for Coupled Model Intercomparison Project Phase 6 (CMIP6). Major updates from NICAM.12, a previous version used for climate simulations, include updates of a cloud microphysics scheme and a land model, an introduction of natural and anthropogenic aerosols and a subgrid-scale orographic gravity wave drag, and improvement of coupling between cloud microphysics and radiation schemes. External forcings were updated to follow a protocol of CMIP6 High Resolution Model Intercomparison Project (HighResMIP). A series of short-term sensitivity experiments were performed to check and understand impacts of the model updates on the simulated mean states. Improvements in the ice water content, the high cloud amounts, the surface air temperature over the Arctic region, the location and the strength of zonal mean subtropical jet, and shortwave radiation over the Africa and the South Asia were found in the NICAM16-S simulations. Some long-standing biases such as the double intertropical convergence zone and smaller low cloud amounts still exist or even worsen in some cases, suggesting further necessity for understanding their mechanisms and upgrading schemes and/or their parameter settings as well as for enhancing horizontal and vertical resolutions.

HighResMIP climate simulations with NICAM and beyond on supercomputer Fugaku

2021 ◽  
Author(s):  
Chihiro Kodama ◽  
Yohei Yamada ◽  
Tomoki Ohno ◽  
Tatsuya Seiki ◽  
Hisashi Yashiro ◽  
...  
Keyword(s):  
Cloud Amount ◽  
Cloud Microphysics ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Climate Simulation ◽  
Surface Model ◽  
Model Intercomparison ◽  
Anthropogenic Aerosols ◽  
Climate Simulations ◽  
Intercomparison Project

<p>The Non-hydrostatic ICosahedral Atmospheric Model (NICAM), a global model with an icosahedral grid system, has been under development for nearly two decades. Here, we present its recent updates for the Coupled Model Intercomparison Project Phase 6, High Resolution Model Intercomparison Project (HighResMIP) and their impact on the simulated mean states using 56-14km mesh model. Major updates include updates of the cloud microphysics scheme and land surface model, introduction of natural and anthropogenic aerosols and a subgrid-scale orographic gravity wave drag scheme, and improvement of the coupling between the cloud microphysics and the radiation schemes. A short-term sensitivity experiments demonstrate improvements in the ice water content, high cloud amount, surface air temperature over the Arctic region, location and strength of zonal mean subtropical jet, and shortwave radiation over Africa and South Asia. The decadal climate simulations further reveal an improvement in the genesis and structure of the tropical cyclones compared with those with the previous model. Finally, we will address outlook toward the cloud-resolving climate simulation based on a fresh benchmark result on supercomputer Fugaku, a flagship supercomputer in Japan.</p>

scholarly journals Arctic cloud cover bias in ECHAM6 and its sensitivity to cloud microphysics and surface fluxes

2018 ◽  
Author(s):  
Jan Kretzschmar ◽  
Marc Salzmann ◽  
Johannes Mülmenstädt ◽  
Johannes Quaas
Keyword(s):  
Cloud Cover ◽  
Climate Models ◽  
Cloud Amount ◽  
Atmospheric Model ◽  
Cloud Microphysics ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
The Arctic ◽  
Phase Partitioning ◽  
Low Level

Abstract. Among the many different feedback mechanisms contributing to the Arctic Amplification, clouds play a very important role in the Arctic climate system through their cloud radiative effect. It is therefore important that climate models simulate basic cloud properties like cloud cover and cloud phase correctly. We compare results from the global atmospheric model ECHAM6 to observations from the CALIPSO satellite active lidar instrument using the COSP satellite simulator. Our results show that the model is able to reproduce the spatial distribution and cloud amount in the Arctic to some extent, but that cloud cover has a positive bias (caused by an overestimation of low-level, liquid containing cloud) in regions where the surface is covered by snow or ice. We explored the sensitivity of cloud cover to the strength of surface heat fluxes, but only by increasing surface mixing the observed cloud cover bias cloud be reduced. As ECHAM6 already mixes too strongly in the Arctic, the cloud cover bias can mainly be attributed to cloud microphysical processes. Improvements in the phase partitioning of Arctic low-level clouds could be achieved by a more effective Wegener–Bergeron–Findeisen process but total cloud cover remained still overestimated. By allowing for a slight supersaturation with respect to ice within the cloud cover scheme, we were able to also reduce this positive cloud cover bias.

scholarly journals Shortwave radiative forcing, rapid adjustment, and feedback to the surface by sulfate geoengineering: analysis of the Geoengineering Model Intercomparison Project G4 scenario

2017 ◽  
Vol 17 (5) ◽  
pp. 3339-3356 ◽  
Author(s):  
Hiroki Kashimura ◽  
Manabu Abe ◽  
Shingo Watanabe ◽  
Takashi Sekiya ◽  
Duoying Ji ◽  
...  
Keyword(s):  
Water Vapour ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Single Layer ◽  
Cloud Amount ◽  
Shortwave Radiation ◽  
Solar Radiation Management ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Rapid Adjustment

Abstract. This study evaluates the forcing, rapid adjustment, and feedback of net shortwave radiation at the surface in the G4 experiment of the Geoengineering Model Intercomparison Project by analysing outputs from six participating models. G4 involves injection of 5 Tg yr−1 of SO2, a sulfate aerosol precursor, into the lower stratosphere from year 2020 to 2069 against a background scenario of RCP4.5. A single-layer atmospheric model for shortwave radiative transfer is used to estimate the direct forcing of solar radiation management (SRM), and rapid adjustment and feedbacks from changes in the water vapour amount, cloud amount, and surface albedo (compared with RCP4.5). The analysis shows that the globally and temporally averaged SRM forcing ranges from −3.6 to −1.6 W m−2, depending on the model. The sum of the rapid adjustments and feedback effects due to changes in the water vapour and cloud amounts increase the downwelling shortwave radiation at the surface by approximately 0.4 to 1.5 W m−2 and hence weaken the effect of SRM by around 50 %. The surface albedo changes decrease the net shortwave radiation at the surface; it is locally strong (∼ −4 W m−2) in snow and sea ice melting regions, but minor for the global average. The analyses show that the results of the G4 experiment, which simulates sulfate geoengineering, include large inter-model variability both in the direct SRM forcing and the shortwave rapid adjustment from change in the cloud amount, and imply a high uncertainty in modelled processes of sulfate aerosols and clouds.

High Cloud Responses to Global Warming Simulated by Two Different Cloud Microphysics Schemes Implemented in the Nonhydrostatic Icosahedral Atmospheric Model (NICAM)

2016 ◽  
Vol 29 (16) ◽  
pp. 5949-5964 ◽  
Author(s):  
Ying-Wen Chen ◽  
Tatsuya Seiki ◽  
Chihiro Kodama ◽  
Masaki Satoh ◽  
Akira T. Noda ◽  
...  
Keyword(s):  
Global Warming ◽  
Radiative Forcing ◽  
Atmospheric Model ◽  
Cloud Microphysics ◽  
Cloud Fraction ◽  
Cirrus Clouds ◽  
Boreal Summer ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Radiative Feedbacks

Abstract This study examines cloud responses to global warming using a global nonhydrostatic model with two different cloud microphysics schemes. The cloud microphysics schemes tested here are the single- and double-moment schemes with six water categories: these schemes are referred to as NSW6 and NDW6, respectively. Simulations of one year for NSW6 and one boreal summer for NDW6 are performed using the nonhydrostatic icosahedral atmospheric model with a mesh size of approximately 14 km. NSW6 and NDW6 exhibit similar changes in the visible cloud fraction under conditions of global warming. The longwave (LW) cloud radiative feedbacks in NSW6 and NDW6 are within the upper half of the phase 5 of the Coupled Model Intercomparison Project (CMIP5)–Cloud Feedback Model Intercomparison Project 2 (CFMIP2) range. The LW cloud radiative feedbacks are mainly attributed to cirrus clouds, which prevail more in the tropics under global warming conditions. For NDW6, the LW cloud radiative feedbacks from cirrus clouds also extend to midlatitudes. The changes in cirrus clouds and their effects on LW cloud radiative forcing (LWCRF) are assessed based on changes in the effective radii of ice hydrometeors () and the cloud fraction. It was determined that an increase in has a nonnegligible impact on LWCRF compared with an increase in cloud fraction.

scholarly journals Shortwave radiative forcing and feedback to the surface by sulphate geoengineering: Analysis of the Geoengineering Model Intercomparison Project G4 scenario

2016 ◽  
Author(s):  
Hiroki Kashimura ◽  
Manabu Abe ◽  
Shingo Watanabe ◽  
Takashi Sekiya ◽  
Duoying Ji ◽  
...  
Keyword(s):  
Water Vapour ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Single Layer ◽  
Cloud Amount ◽  
Shortwave Radiation ◽  
Solar Radiation Management ◽  
Model Intercomparison ◽  
Feedback Effects ◽  
Intercomparison Project

Abstract. This study evaluates the forcing and feedback of net shortwave radiation at the surface in the G4 experiment of the Geoengineering Model Intercomparison Project by analysing outputs from six participating models. G4 involves injection of 5 Tg yr−1 of SO2, a sulphate aerosol precursor, into the lower stratosphere from year 2020 to 2070 against a background scenario of RCP4.5. A single layer atmospheric model for shortwave radiative transfer is used to estimate the direct forcing of solar radiation management (SRM) and feedback effects from changes in the water vapour amount, cloud amount, and surface albedo (compared with RCP4.5). The analysis shows that the globally and temporally averaged SRM forcing ranges from −3.6 to −1.6 W m−2, depending on the model. The feedback effects due to changes in the water vapour and cloud amounts on net shortwave radiation have heating effects ranging from approximately 0.4 to 1.5 W m−2 and weaken the effect of SRM by around 50 %. The surface albedo changes have a cooling effect, which is locally strong (~ 4 W m−2) in snow and sea ice melting regions, but minor for the global average. The analyses show that the results of the G4 experiment, which simulates sulphate geoengineering, include large inter-model variability both in the direct SRM forcing and the feedback from changes in the cloud amount, and imply a high uncertainty in modelled processes of sulphate aerosols and clouds.

scholarly journals The Transpose-AMIP II Experiment and Its Application to the Understanding of Southern Ocean Cloud Biases in Climate Models

2013 ◽  
Vol 26 (10) ◽  
pp. 3258-3274 ◽  
Author(s):  
K. D. Williams ◽  
A. Bodas-Salcedo ◽  
M. Déqué ◽  
S. Fermepin ◽  
B. Medeiros ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Large Scale ◽  
Climate Models ◽  
Layer Structure ◽  
Coupled Model ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Shortwave Radiation ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract The Transpose-Atmospheric Model Intercomparison Project (AMIP) is an international model intercomparison project in which climate models are run in “weather forecast mode.” The Transpose-AMIP II experiment is run alongside phase 5 of the Coupled Model Intercomparison Project (CMIP5) and allows processes operating in climate models to be evaluated, and the origin of climatological biases to be explored, by examining the evolution of the model from a state in which the large-scale dynamics, temperature, and humidity structures are constrained through use of common analyses. The Transpose-AMIP II experimental design is presented. The project requests participants to submit a comprehensive set of diagnostics to enable detailed investigation of the models to be performed. An example of the type of analysis that may be undertaken using these diagnostics is illustrated through a study of the development of cloud biases over the Southern Ocean, a region that is problematic for many models. Several models share a climatological bias for too little reflected shortwave radiation from cloud across the region. This is found to mainly occur behind cold fronts and/or on the leading side of transient ridges and to be associated with more stable lower-tropospheric profiles. Investigation of a case study that is typical of the bias and associated meteorological conditions reveals the models to typically simulate cloud that is too optically and physically thin with an inversion that is too low. The evolution of the models within the first few hours suggests that these conditions are particularly sensitive and a positive feedback can develop between the thinning of the cloud layer and boundary layer structure.

scholarly journals CAS FGOALS-f3-L Large-ensemble Simulations for the CMIP6 Polar Amplification Model Intercomparison Project

2021 ◽  
Author(s):  
Bian He ◽  
Xiaoqi Zhang ◽  
Anmin Duan ◽  
Qing Bao ◽  
Yimin Liu ◽  
...  
Keyword(s):  
Time Lag ◽  
The Arctic ◽  
Global Ocean ◽  
Arctic Amplification ◽  
Model Intercomparison ◽  
Large Ensemble ◽  
Sea Ice Concentration ◽  
Ensemble Simulations ◽  
Polar Amplification ◽  
Intercomparison Project

AbstractLarge-ensemble simulations of the atmosphere-only time-slice experiments for the Polar Amplification Model Intercomparison Project (PAMIP) were carried out by the model group of the Chinese Academy of Sciences (CAS) Flexible Global Ocean-Atmosphere-Land System (FGOALS-f3-L). Eight groups of experiments forced by different combinations of the sea surface temperature (SST) and sea ice concentration (SIC) for pre-industrial, present-day, and future conditions were performed and published. The time-lag method was used to generate the 100 ensemble members, with each member integrating from 1 April 2000 to 30 June 2001 and the first two months as the spin-up period. The basic model responses of the surface air temperature (SAT) and precipitation were documented. The results indicate that Arctic amplification is mainly caused by Arctic SIC forcing changes. The SAT responses to the Arctic SIC decrease alone show an obvious increase over high latitudes, which is similar to the results from the combined forcing of SST and SIC. However, the change in global precipitation is dominated by the changes in the global SST rather than SIC, partly because tropical precipitation is mainly driven by local SST changes. The uncertainty of the model responses was also investigated through the analysis of the large-ensemble members. The relative roles of SST and SIC, together with their combined influence on Arctic amplification, are also discussed. All of these model datasets will contribute to PAMIP multi-model analysis and improve the understanding of polar amplification.

scholarly journals CAS-LSM Datasets for the CMIP6 Land Surface Snow and Soil Moisture Model Intercomparison Project

2021 ◽  
Author(s):  
Binghao Jia ◽  
Longhuan Wang ◽  
Yan Wang ◽  
Ruichao Li ◽  
Xin Luo ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
Grid Point ◽  
Global Ocean ◽  
Surface Model ◽  
Past Century ◽  
Model Intercomparison ◽  
Soil Moisture Model ◽  
Surface Snow ◽  
Intercomparison Project

AbstractThe datasets of the five Land-offline Model Intercomparison Project (LMIP) experiments using the Chinese Academy of Sciences Land Surface Model (CAS-LSM) of CAS Flexible Global-Ocean-Atmosphere-Land System Model Grid-point version 3 (CAS FGOALS-g3) are presented in this study. These experiments were forced by five global meteorological forcing datasets, which contributed to the framework of the Land Surface Snow and Soil Moisture Model Intercomparison Project (LS3MIP) of CMIP6. These datasets have been released on the Earth System Grid Federation node. In this paper, the basic descriptions of the CAS-LSM and the five LMIP experiments are shown. The performance of the soil moisture, snow, and land-atmosphere energy fluxes was preliminarily validated using satellite-based observations. Results show that their mean states, spatial patterns, and seasonal variations can be reproduced well by the five LMIP simulations. It suggests that these datasets can be used to investigate the evolutionary mechanisms of the global water and energy cycles during the past century.

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