Land Surface Model (LSM 1.0) for Ecological, Hydrological, Atmospheric Studies

The NCAR LSM 1.0 is a land surface model developed to examine biogeophysical and biogeochemical land-atmosphere interactions, especially the effects of land surfaces on climate and atmospheric chemistry. It can be run coupled to an atmospheric model or uncoupled, in a stand-alone mode, if an atmospheric forcing is provided. The model runs on a spatial grid that can range from one point to global. The model was designed for coupling to atmospheric numerical models. Consequently, there is a compromise between computational efficiency and the complexity with which the necessary atmospheric, ecological, and hydrologic processes are parameterized. The model is not meant to be a detailed micrometeorological model, but rather a simplified treatment of surface fluxes that reproduces at minimal computational cost the essential characteristics of land-atmosphere interactions important for climate simulations. The model is a complete executable code with its own time-stepping driver, initialization (subroutine lsmini), and main calling routine (subroutine lsmdrv). When coupled to an atmospheric model, the atmospheric model is the time-stepping driver. There is one call to subroutine lsmini during initialization to initialize all land points in the domain; there is one call per time step to subroutine lsmdrv to calculate surface fluxes and update the ecological, hydrological, and thermal state for all land points in the domain. The model writes its own restart and history files. These can be turned off if appropriate. Available for downloading from the ORNL DAAC are the LMS Model Documentation and User's Guide, the model source code, input data set, and scripts for running the model. Applications of the model are described in two additional companion files.

NCAR LSM 1.0 是一款旨在探究生物物理和生物地球化学陆气相互作用的陆地表面模型，尤其是研究地表对气候和大气化学的影响。该模型可耦合于大气模型运行，亦可在提供大气强迫条件下独立运行。模型在空间网格上运行，其范围可从单点至全球。该模型专为与大气数值模型耦合设计，因此在计算效率与所需大气、生态和水文过程参数化的复杂性之间达成了一种折中。模型并非旨在提供详细的微气象模型，而是一种简化的地表通量处理方法，以最低的计算成本再现了陆气相互作用对气候模拟至关重要的基本特征。该模型包含完整的可执行代码，具备自身的时间步进驱动程序、初始化（子程序lsmini）和主要调用程序（子程序lsmdrv）。当与大气模型耦合时，大气模型作为时间步进驱动程序。在初始化阶段，将对子程序lsmini进行一次调用以初始化域内所有陆地点；在每一步时间步长中，将对子程序lsmdrv进行一次调用以计算地表通量并更新域内所有陆地点的生态、水文和热状态。模型会自行写入重启和历史文件，如需关闭此功能，可进行相应设置。ORNL DAAC 提供了 LMS 模型文档和用户指南、模型源代码、输入数据集以及运行模型的脚本。模型的应用描述包含在两个额外的伴随文件中。