EKS98

EKS98
Name	EKS98
Type	Computational model
Developer	International consortium
Year	1998
Field	Climate science
Related	General Circulation Models, Earth system models, Integrated Assessment Models

EKS98 is a computational framework introduced in 1998 for coupled atmosphere–ocean–land surface simulation, designed to integrate radiative transfer, hydrology, and biogeochemical cycles. It was developed by an international consortium drawing on work from Intergovernmental Panel on Climate Change, National Aeronautics and Space Administration, European Centre for Medium-Range Weather Forecasts, Max Planck Institute for Meteorology, and Met Office. EKS98 influenced subsequent projects at institutions such as NOAA, Scripps Institution of Oceanography, Lawrence Livermore National Laboratory, and Potsdam Institute for Climate Impact Research.

Overview

EKS98 combined components originating in legacy systems from GFDL, Hadley Centre, ECMWF, IPSL, and NCAR to form a unified platform for multi-decadal simulations. The framework emphasized coupling strategies comparable to those used in CMIP1 and later echoed in CMIP2 and CMIP3, facilitating experiments aligned with protocols from World Climate Research Programme and datasets produced for United Nations Framework Convention on Climate Change submissions. EKS98's modular design allowed integration with observational programs such as TOGA, WOCE, Argo, and GCOS.

Theoretical Foundation

The theoretical foundation of EKS98 drew on dynamical cores and parameterizations used in models by Geophysical Fluid Dynamics Laboratory, European Space Agency, NOAA Geophysical Fluid Dynamics Laboratory, Princeton University, and Massachusetts Institute of Technology. It incorporated Navier–Stokes formulations adapted from numerical schemes developed at Los Alamos National Laboratory and stability analyses influenced by research at ETH Zurich and University of Oxford. Radiative transfer modules reflected approaches from Ramanathan, Kiehl, and Schwarzkopf-style implementations used at NASA Goddard Institute for Space Studies and CSIRO.

Methodology

EKS98 employed a split-explicit time-stepping method analogous to techniques used at NCAR Community Climate System Model and the HadCM3 family, with vertical discretization schemes paralleling those adopted by ERA-40 reanalyses and JRA-55. Spatial discretization was implemented on grids similar to those developed at ECMWF and Met Office Hadley Centre, while tracer advection schemes were informed by algorithms from NOAA and Scripps Institution of Oceanography. Coupling intervals and flux exchange protocols referenced standards from WCRP and practices tested in AOGCM intercomparison projects.

Parameterization and Inputs

Key parameterizations in EKS98 covered cloud microphysics, convection, and land–atmosphere interactions, drawing on formulations used by Manabe, Arakawa, Kuo, and research programs at University of Washington and Columbia University. Ocean mixing and thermocline processes reflected parameter choices similar to those in Levitus climatologies and TRIFFID-style vegetation modules. Forcing datasets included sea surface temperatures and greenhouse gas concentrations used in IPCC Second Assessment Report experiments, and boundary conditions leveraged observational archives from HadISST, GPCP, CRU, and NOAA ERSST.

Applications and Impact

EKS98 was applied to multi-decadal climate sensitivity studies, attribution analyses for extreme events similar to investigations by World Meteorological Organization and IPCC, and regional downscaling efforts akin to methods used by CORDEX. It supported assessments that informed policy venues such as Kyoto Protocol negotiations and national assessments conducted by US Global Change Research Program and European Environment Agency. The framework also contributed to methodological advances later adopted in projects at NERSC, Oak Ridge National Laboratory, Canadian Centre for Climate Modelling and Analysis, and CSIRO.

Limitations and Criticism

Critics noted that EKS98 inherited biases documented in intercomparison studies like those coordinated by PCMDI and had difficulty representing mesoscale processes emphasized by Danish Meteorological Institute and Japan Meteorological Agency research. Its treatment of aerosol–cloud interactions and ice-sheet dynamics lagged behind later formulations developed at British Antarctic Survey, Alfred Wegener Institute, and University of Toronto. Computational constraints limited ensemble sizes relative to those produced on facilities such as Oak Ridge Leadership Computing Facility and NERSC.

Related Models and Developments

EKS98 influenced successor systems including generations of CMIP-participating models, architectures seen in CESM, HadGEM, MPI-ESM, ACCESS, and hybrid frameworks developed at Princeton. Subsequent developments incorporated data assimilation methods advanced in 3D-Var and 4D-Var systems used by ECMWF and JMA, and benefited from high-performance computing trends exemplified by projects at Argonne National Laboratory and Lawrence Berkeley National Laboratory.

Category:Climate models