ICON-L/JSBACH (Land)

ICON-Land is a framework developed at MPI-M for the modelling of land processes in ICON and can be used as a stand-alone land-surface model (Nabel et al., 2020) as well as in the fully coupled ICON Earth System Model (Jungclaus et al., JAMES, in review) and in the ICON-A atmosphere-only model (Schneck et al., 2021, in preparation). It is specifically designed in a modular way for the integration of concurrent and alternative process and surface descriptions in a flexible and easy-to-use way. Currently, specific process implementations include the JSBACHv4 (JSBACH version 4) and the QUINCY model configurations. ICON-Land development is governed by the ICON-Land Steering Group and the ICON-Land Management Team.

ICON-Land Framework

The ICON-Land framework has been designed to systematically separate the infrastructure necessary to implement physical, biogeophysical and biogeochemical land processes from the concrete process implementations which are accessed by abstract interfaces. A further goal was the ability to support different experimental configurations of varying scope and complexity to be used in different global, regional or single-site applications, coupled online to an atmosphere model or driven offline by atmospheric observations.

ICON-Land is implemented in an object-oriented and modular way in Fortran2003/2008. Hierarchical trees are used for the flexible description of surface characteristics (tiles; see figure below for an illustration) and matter cycles (pools). Scientific code (processes) is clearly separated from the infrastructure. ICON-Land is a self-contained package while using only a basic infrastructure for I/O, parallel domain decomposition, time control, etc. from the ICON model via a relatively small number of interface routines. It has been ported to accelerated architectures (GPUs) by using the CLAW single column abstraction (Clement et al., 2019).

JSBACHv4

JSBACHv4 is a dynamic global vegetation model (DGVM) implemented within the ICON-Land framework, but is also implemented as the land surface model used in the ICON-ESM 1.0 Earth System Model, where it provides the lower boundary conditions to the atmosphere (Jungclaus et al., 2021). JSBACHv4 is a re-implementation of JSBACHv3 in the new framework. JSBACHv3 has been the land component of the MPI-M ECHAM and MPI-ESM models used in many modelling studies over the last decades (Giorgetta et al., 2013; Mauritsen et al., 2019) including numerous model intercomparisons such as TRENDY (Friedlingstein et al., 2020), C4MIP (Arora et al., 2020) and LUMIP (Boysen et al., 2020). JSBACHv4 in ICON-ESM 1.0 currently includes the fast physical processes as well as biogeochemical processes to simulate the natural land carbon cycle, disturbances and anthropogenic land cover change, a subset of the processes described in Reick et al. (2021).

The surface energy balance and the soil thermal layers on land are coupled implicitly to the vertical diffusion scheme of ICON-A, which can be applied in a simplified manner to be run with observed meteorology for stand-alone applications. Plant productivity by photosynthesis, phenology (leaf area index), roughness lengths for momentum and heat, and visible and near-infrared albedos are computed on a flexible number of tiles representing sub-grid heterogeneity by plant functional types. Heat and water dynamics in the soil are described to a depth of about 10 m and are coupled to calculations of surface runoff and sub-surface drainage and the resulting river discharge through a hydrologic discharge model (Hagemann & Dümenil, 1997; Riddick et al., 2018). A five-layer snow model is applied and the soil dynamics include freezing water and phase changes between liquid and frozen water (Ekici et al., 2014, de Vrese et al., 2021).

JSBACHv4 also features a new scheme of forest age classes combining computationally efficient age-dependent simulation of all relevant processes with a tracking of the exact forest age (Nabel et al., 2020). This makes the representation of age-based forest management and its biogeophysical as well as carbon cycle impacts possible.
 

QUINCY

QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system, Thum et al. 2019) has been developed at the MPI for Biogeochemistry as an alternative, more comprehensive representation of biogeochemical processes for ICON-Land. QUINCY is integrated with ICON-Land through a set of defined interfaces that affect the biological control of the land surface’s radiation balance, momentum and heat transfer as well as its water balance. It follows a modular design that allows to integrate fundamental, fast biospheric processes with increasing degree of complexity from a prescribed phenology mode, a vegetation dynamics mode to a fully coupled BGC vegetation-soil model. QUINCY  also serves as test-bed for novel model components, e.g. representations of soil biogeochemical processes (Yu et al. 2020a,b).

QUINCY simulates the element cycling of carbon, nitrogen, and phosphorus in terrestrial ecosystems, and includes novel representations of source/sink limited plant growth; the acclimation of many ecophysiological processes; an explicit representation of vertical soil processes to separate litter and soil organic matter dynamics; a range of new diagnostics (leaf chlorophyll; isotope tracers) to allow for a more in-depth model evaluation. Case-studies include the evaluation against standard biosphere benchmarks (Thum et al. 2019), in particular ecosystem manipulation experiments (Caldararu et al. 2020) as well as long-term monitoring data (Caldararu et al. 2021).

ICON-Land is governed by the ICON-Land Steering Group and the ICON-Land Management Team. The steering group includes the representatives from several groups contributing to development of models of the land processes within the ICON-Land infrastructure, and is headed by the ICON-Land Management Team. The steering group meets two to three times a year in order to coordinate and facilitate ICON-Land development across the different scientific institutions contributing to ICON-Land, and to decide on strategic developments.

The ICON-Land Management Team is composed of four persons and meets monthly to make operational decisions. Please contact the ICON-Land Management Group to discuss opportunities for collaboration as well as contributions to model inter-comparison studies. As our resources are limited, we cannot promise support on a regular basis, but are interested in supporting and contributing to novel research on the land's role in the Earth System.

 

ICON-Land Management Team

Member

Function

Institution

Focus

E-mail contact

Sönke Zaehle

Scientific lead

MPI-BGC

biogeochemical cycles, coupling to energy and water cycles

szaehle(at)bgc-jena.mpg.de

Victor Brovkin

´´

MPI-M

Land-climate interactions, esp. in high latitudes

victor.brovkin(at)mpimet.mpg.de

Julia Pongratz

´´

LMU

land use and land management, climate-carbon cycle interactions

julia.pongratz(at)lmu.de

Reiner Schnur

Technical lead

MPI-M

Code development

reiner.schnur(at)mpimet.mpg.de

 

Publications with JSBACH

 

References

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