Showing papers by "Chihiro Kodama published in 2021"
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TL;DR: The NICAM16-S as mentioned in this paper, the latest stable version of NICAM (NICAM.16), modified for the Coupled Model Evaluation Project Phase 6, High Resolution Model Intercomparison Project (HighResMIP), has been used for climate simulations, including updates of the cloud microphysics scheme and land surface model.
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.
30 citations
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TL;DR: In this article, the authors examined projected changes in tropical cyclones using six global atmospheric models with medium-to-high horizontal resolutions included in the sixth phase of the Coupled Model Intercomparison Project/High-Resolution Model intercomparisons Project.
Abstract: Previous projections of the frequency of tropical cyclone genesis due to global warming, even in terms of sign of the change, depends on the chosen model simulation. Here, we systematically examine projected changes in tropical cyclones using six global atmospheric models with medium-to-high horizontal resolutions included in the sixth phase of the Coupled Model Intercomparison Project/High-Resolution Model Intercomparison Project. Changes in the frequency of tropical cyclone genesis could be broken down into the contributions from (i) the tropical cyclone seed, a depression having a closed contour of sea level pressure with a warm core and (ii) the survival rate, the ratio of the frequency of tropical cyclone genesis to that of tropical cyclone seeds. The multi-model ensemble mean indicates that tropical cyclone genesis frequencies are significantly decreased during the period 1990–2049, which is attributable to changes in tropical cyclone seeds. Analysis of the individual models shows that although most models project a more or less decreasing trend in tropical cyclone genesis frequencies and seeds, the survival rate also contributes to the result in some models. The present study indicates the usefulness of decomposition into the frequency of the tropical cyclone seeds and the survival rate to understand the cause of uncertainty in projected frequencies of tropical cyclone genesis.
26 citations
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National Center for Atmospheric Research1, Deutscher Wetterdienst2, University of Reading3, University of Washington4, Geophysical Fluid Dynamics Laboratory5, European Centre for Medium-Range Weather Forecasts6, Max Planck Society7, Stony Brook University8, Japan Agency for Marine-Earth Science and Technology9, Helmut Schmidt University10, Goddard Space Flight Center11, Met Office12, University of Tokyo13
TL;DR: In this paper, the authors evaluated nine global storm resolving models in their ability to simulate tropical cyclones (TCs) and found that the models produce realistic TCs and remove longstanding issues known from global models such as the deficiency in accurately simulating TC intensity.
Abstract: Recent progress in computing and model development has initiated the era of global storm-resolving modeling, and with it the potential to transform weather and climate prediction. Within the general theme of vetting this new class of models, the present study evaluates nine global-storm resolving models in their ability to simulate tropical cyclones (TCs). Results indicate that, broadly speaking, the models produce realistic TCs and remove longstanding issues known from global models such as the deficiency in accurately simulating TC intensity. However, TCs are strongly affected by model formulation, and all models suffer from unique biases regarding the number of TCs, intensity, size, and structure. Some models simulated TCs better than others, but no single model was superior in every way. The overall results indicate that global storm-resolving models can open a new chapter in TC prediction, but they need to be improved to unleash their full potential.
24 citations
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11 citations
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3 citations