Eddy-resolving Simulation of CAS-LICOM3 for Phase 2 of the Ocean Model Intercomparison Project

A 61-year(1958–2018)global eddy-resolving dataset for phase 2 of the Ocean Model Intercomparison Project has been produced by the version 3 of Chinese Academy of Science,the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics(LASG/IAP)Climate system Ocean Model(CAS-LICOM3).The monthly and a part of the surface daily data in this study can be accessed on the Earth System Grid Federation(ESGF)node.Besides the details of the model and experiments,the evolutions and spatial patterns of large-scale and mesoscale features are also presented.The mesoscale features are reproduced well in the high-resolution simulation,as the mesoscale activities can contribute up to 50%of the total SST variability in eddy-rich regions.Also,the large-scale circulations are remarkably improved compared with the low-resolution simulation,such as the climatological annual mean SST(the RMSE is reduced from 0.59°C to 0.47°C,globally)and the evolution of Atlantic Meridional Overturning Circulation.The preliminary evaluation also indicates that there are systematic biases in the salinity,the separation location of the western boundary currents,and the magnitude of eddy kinetic energy.All these biases are worthy of further investigation.

The Super-large Ensemble Experiments of CAS FGOALS-g3

A super-large ensemble simulation dataset with 110 members has been produced by the fully coupled model FGOALS-g3 developed by researchers at the Institute of Atmospheric Physics,Chinese Academy of Sciences.This is the first dataset of large ensemble simulations with a climate system model developed by a Chinese modeling center.The simulation has the largest realizations up to now worldwide in terms of single-model initial-condition large ensembles.Each member includes a historical experiment(1850-2014)and an experiment(2015-99)under the very high greenhouse gas emissions Shared Socioeconomic Pathway scenario(SSP5-8.5).The dataset includes monthly and daily temperature,precipitation,and other variables,requiring storage of 275 TB.Additionally,the surface air temperature(SAT)and land precipitation simulated by the FGOALS-g3 super-large ensemble have been validated and projected.The ensemble can capture the response of SAT and land precipitation to external forcings well,and the internal variabilities can be quantified.The availability of more than 100 realizations will help researchers to study rare events and improve the understanding of the impact of internal variability on forced climate changes.

Typhoon storm surge ensemble forecast based on GPU technique

The accuracy of typhoon forecasts plays an important role in the prediction of storm surges.The uncertainty of a typhoon’s intensity and track means it is necessary to use an ensemble model to predict typhoon storm surges.A hydrodynamic model,which is operational at the National Marine Environmental Forecasting Center,is applied to conduct surge simulations for South China coastal areas using the best track data with parametric wind and pressure models.The results agree well with tidal gauge observations.To improve the calculation efficiency,the hydrodynamic model is modified using CUDA Fortran.The calculation results are almost the same as those from the original model,but the calculation time is reduced by more than 99%.A total of 150 typhoon cases are generated by combining 50 typhoon tracks from the European Centre for Medium-Range Weather Forecasts with three possible typhoon intensity forecasts.The surge ensembles are computed by the improved hydrodynamic model.Based on the simulated storm surges for the different typhoon cases,ensemble and probability forecast products can be provided.The mean ensemble results and probability forecast products are shown to agree well with the observed storm surge caused by Typhoon Mangkhut.The improved model is highly suitable for ensemble numerical forecasts,providing better forecast products for decision-making,and can be easily implemented to run on regular workstations.