Chihiro Kodama

Bio: Chihiro Kodama is an academic researcher from Japan Agency for Marine-Earth Science and Technology. The author has contributed to research in topics: Atmospheric model & NICAM. The author has an hindex of 19, co-authored 52 publications receiving 1699 citations. Previous affiliations of Chihiro Kodama include Tohoku University.

High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP6

Abstract: . Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950–2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.

The Non-hydrostatic Icosahedral Atmospheric Model: description and development

Abstract: This article reviews the development of a global non-hydrostatic model, focusing on the pioneering research of the Non-hydrostatic Icosahedral Atmospheric Model (NICAM). Very high resolution global atmospheric circulation simulations with horizontal mesh spacing of approximately O (km) were conducted using recently developed supercomputers. These types of simulations were conducted with a specifically designed atmospheric global model based on a quasi-uniform grid mesh structure and a non-hydrostatic equation system. This review describes the development of each dynamical and physical component of NICAM, the assimilation strategy and its related models, and provides a scientific overview of NICAM studies conducted to date.

DYAMOND: the DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains

Abstract: A review of the experimental protocol and motivation for DYAMOND, the first intercomparison project of global storm-resolving models, is presented. Nine models submitted simulation output for a 40-day (1 August–10 September 2016) intercomparison period. Eight of these employed a tiling of the sphere that was uniformly less than 5 km. By resolving the transient dynamics of convective storms in the tropics, global storm-resolving models remove the need to parameterize tropical deep convection, providing a fundamentally more sound representation of the climate system and a more natural link to commensurately high-resolution data from satellite-borne sensors. The models and some basic characteristics of their output are described in more detail, as is the availability and planned use of this output for future scientific study. Tropically and zonally averaged energy budgets, precipitable water distributions, and precipitation from the model ensemble are evaluated, as is their representation of tropical cyclones and the predictability of column water vapor, the latter being important for tropical weather.

A 20-Year Climatology of a NICAM AMIP-Type Simulation

Abstract: Chihiro KODAMA, Yohei YAMADA, Akira T. NODA Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan Kazuyoshi KIKUCHI International Pacific Research Center, University of Hawaii, Hawaii, USA Yoshiyuki KAJIKAWA RIKEN Advanced Institute for Computational Science, Kobe, Japan Tomoe NASUNO Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan Tomohiko TOMITA Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan Tsuyoshi YAMAURA RIKEN Advanced Institute for Computational Science, Kobe, Japan Hiroshi G. TAKAHASHI Tokyo Metropolitan University, Hachioji, Japan Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan Masayuki HARA Center for Environmental Science in Saitama, Kazo, Japan Yoshio KAWATANI Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan Masaki SATOH Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan and Masato SUGI Meteorological Research Institute, Tsukuba, Japan (Manuscript received 6 November 2014, in final form 17 March 2015)

Projected Future Changes in Tropical Cyclones Using the CMIP6 HighResMIP Multimodel Ensemble.

Abstract: Future changes in tropical cyclone properties are an important component of climate change impacts and risk for many tropical and mid-latitude countries. In this study we assess the performance of ...

Different glacier status with atmospheric circulations in Tibetan Plateau and surroundings

Abstract: Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.

Future climate risk from compound events

Abstract: Floods, wildfires, heatwaves and droughts often result from a combination of interacting physical processes across multiple spatial and temporal scales. The combination of processes (climate drivers and hazards) leading to a significant impact is referred to as a ‘compound event’. Traditional risk assessment methods typically only consider one driver and/or hazard at a time, potentially leading to underestimation of risk, as the processes that cause extreme events often interact and are spatially and/or temporally dependent. Here we show how a better understanding of compound events may improve projections of potential high-impact events, and can provide a bridge between climate scientists, engineers, social scientists, impact modellers and decision-makers, who need to work closely together to understand these complex events.

Global Warming Pattern Formation: Sea Surface Temperature and Rainfall

Abstract: Spatial variations in sea surface temperature (SST) and rainfall changes over the tropics are investigated based on ensemble simulations for the first half of the twenty-first century under the greenhouse gas (GHG) emission scenario A1B with coupled ocean–atmosphere general circulation models of the Geophysical Fluid Dynamics Laboratory (GFDL) and National Center for Atmospheric Research (NCAR). Despite a GHG increase that is nearly uniform in space, pronounced patterns emerge in both SST and precipitation. Regional differences in SST warming can be as large as the tropical-mean warming. Specifically, the tropical Pacific warming features a conspicuous maximum along the equator and a minimum in the southeast subtropics. The former is associated with westerly wind anomalies whereas the latter is linked to intensified southeast trade winds, suggestive of wind–evaporation–SST feedback. There is a tendency for a greater warming in the northern subtropics than in the southern subtropics in accordance ...