Community Land Model

Community Land Model
Name	Community Land Model
Developer	National Center for Atmospheric Research
Released	0 2002
Genre	Land surface model
License	Open source

Community Land Model. The Community Land Model is a sophisticated, open-source land surface model developed to simulate the physical, chemical, and biological processes occurring at the Earth's land surface. It serves as a critical component for understanding the exchange of energy, water, aerosols, and carbon dioxide between the terrestrial ecosystem and the atmosphere. The model is a core part of the Community Earth System Model and is widely used by the international scientific community for climate projections and environmental research.

Overview

The model represents the complex interactions between vegetation, soil, snow, and the overlying atmosphere across global landscapes. It calculates key variables such as surface albedo, evapotranspiration, and soil moisture to determine the land's influence on climate. By integrating biogeophysical and biogeochemical cycles, it provides essential data for assessing climate change impacts, water resources, and carbon cycle feedbacks. Its development is spearheaded by the Climate and Global Dynamics Laboratory at the National Center for Atmospheric Research.

Model components

Key modules within the framework handle distinct processes, including a vegetation canopy model that computes radiation transfer and photosynthesis. The hydrology component simulates surface runoff, subsurface drainage, and river routing, while the biogeochemistry module tracks carbon and nitrogen pools in plants and soils. Separate schemes model snowpack accumulation and melt, soil temperature profiles, and urban heat islands. These components are coupled through tightly integrated energy and water budgets.

Development and versions

Initial development stemmed from the Land Surface Model used in the Community Climate System Model. The first standalone version was released in 2002, with subsequent major updates like CLM4 and CLM5 introducing advanced plant hydraulics and crop modeling. Development is a collaborative effort involving NCAR, the Department of Energy, and universities like the University of Texas at Austin. The model's code is managed on platforms like GitHub and follows the CESM release cycle.

Applications and research

Scientists employ the tool to study drought dynamics, permafrost thaw, and deforestation impacts in regions like the Amazon rainforest and the Arctic. It informs reports by the Intergovernmental Panel on Climate Change and supports research at institutions like NASA and the Max Planck Institute for Meteorology. Applications extend to evaluating land use change, predicting wildfire risk, and assessing future agricultural yields under different emissions scenarios.

Integration with Earth system models

It is primarily coupled as the land component of the Community Earth System Model, exchanging data with the Community Atmosphere Model and Parallel Ocean Program. This integration allows for fully interactive simulations of climate system feedbacks. The model also interfaces with the Energy Exascale Earth System Model developed by the DOE and can be used in offline mode forced by atmospheric reanalysis data from NCEP or ERA5.

Data and input requirements

Simulations require high-resolution global datasets for parameters like soil texture, plant functional types, and leaf area index. These are often derived from satellites such as MODIS and projects like the Global Soil Wetness Project. Atmospheric forcing data, including precipitation and solar radiation, come from products like CRU TS or GLDAS. Model output is typically formatted in NetCDF and analyzed using tools like Python and the Climate Data Operators.

Limitations and future directions

Current challenges include accurately representing groundwater processes, wetland methane emissions, and human management of irrigation. Future development aims to incorporate finer spatial scales, improved cryosphere interactions, and enhanced coupling with atmospheric chemistry models. Efforts are also focused on better quantifying uncertainties through projects like the International Land Model Benchmarking project and leveraging exascale computing resources at facilities like the Oak Ridge National Laboratory.

Category:Climate modeling Category:Atmospheric science Category:Scientific simulation software