Regional Projection of Tropical-Cyclone-Induced Extreme Precipitation around Japan Based on Large Ensemble Simulations

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.

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Variability of Tropical Cyclone Frequency Over the Western North Pacific in 2018–2020

Frontiers in Climate ◽

10.3389/fclim.2021.770785 ◽

2021 ◽

Vol 3 ◽

Author(s):

Tomomichi Ogata ◽

Yuya Baba

Keyword(s):

Tropical Cyclone ◽

North Pacific ◽

General Circulation ◽

Western North Pacific ◽

Circulation Model ◽

Atmospheric Variability ◽

Convection Scheme ◽

Planetary Scale ◽

Ensemble Simulations ◽

Potential Index

In this study, we examine the tropical cyclone (TC) activity over the western North Pacific (WNP) in 2018–2020 and its relationship with planetary scale convection and circulation anomalies, which play an important role for TC genesis. To determine the sea surface temperature (SST)-forced atmospheric variability, atmospheric general circulation model (AGCM) ensemble simulations are executed along with the observed SST. For AGCM experiments, we use two different convection schemes to examine uncertainty in convective parameterization and robustness of simulated atmospheric response. The observed TC activity and genesis potential demonstrated consistent features. In our AGCM ensemble simulations, the updated convection scheme improves the simulation ability of observed genesis potential as well as planetary scale convection and circulation features, e.g., in September–October–November (SON), a considerable increase in the genesis potential index over the WNP in SON 2018, WNP in SON 2019, and South China Sea (SCS) in SON 2020, which were not captured in the Emanuel scheme, have been simulated in the updated convection scheme.

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Surface and top-of-atmosphere radiative feedback kernels for CESM-CAM5

Earth System Science Data ◽

10.5194/essd-10-317-2018 ◽

2018 ◽

Vol 10 (1) ◽

pp. 317-324 ◽

Cited By ~ 29

Author(s):

Angeline G. Pendergrass ◽

Andrew Conley ◽

Francis M. Vitt

Keyword(s):

Water Vapor ◽

Greenhouse Gases ◽

Surface Temperature ◽

Radiative Forcing ◽

Surface Albedo ◽

Large Ensemble ◽

Radiative Fluxes ◽

Radiative Feedback ◽

Ensemble Simulations ◽

Temperature Water

Abstract. Radiative kernels at the top of the atmosphere are useful for decomposing changes in atmospheric radiative fluxes due to feedbacks from atmosphere and surface temperature, water vapor, and surface albedo. Here we describe and validate radiative kernels calculated with the large-ensemble version of CAM5, CESM1.1.2, at the top of the atmosphere and the surface. Estimates of the radiative forcing from greenhouse gases and aerosols in RCP8.5 in the CESM large-ensemble simulations are also diagnosed. As an application, feedbacks are calculated for the CESM large ensemble. The kernels are freely available at https://doi.org/10.5065/D6F47MT6, and accompanying software can be downloaded from https://github.com/apendergrass/cam5-kernels.

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