Regional Climate Models (RCMs) are practical downscaling tools to yield regional climate information for assessing the impacts of climate variability and change. The Pacific Northwest National Laboratory (PNNL) RCM, based on the Penn State/NCAR Mesoscale Model (MM5), features a novel subgrid treatment of orographic precipitation for coupling climate, hydrologic, and ecologic processes at the watershed scale. The parameterization aggregates subgrid variations of surface topography into a finite number of surface elevation bands. An airflow model and a thermodynamic model are used to parameterize the orographic uplift/descent as air parcels cross over mountain barriers or valleys. The parameterization has significant performance advantages over nesting to achieve comparable resolution of climate information; however, previous implementations of the subgrid scheme required significant modification to the host MM5 model, prohibiting its incorporation within the NCAR-supported community version of MM5. With this effort, software engineering challenges have been addressed to incorporate, parallelize, and load-balance the PNNL subgrid scheme with minimum changes to MM5. The result is an efficient, maintainable tool for regional climate simulation and a step forward in the development of an MM5-based community regional climate model.
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机译：区域气候模型（RCMS）是实用较低的工具，以产生区域气候信息，以评估气候变异性和变革的影响。基于Penn State / Ncar Messcale模型（MM5）的太平洋西北国家实验室（PNNL）RCM采用了一种新的亚科地面处理，用于在流域凝视下耦合气候，水文和生态过程的地形沉淀。参数化将表面形貌的子底级变化聚集成有限数量的表面升高带。气流模型和热力学模型用于将地形隆起/下降参数化，因为空气包裹在山障碍或山谷上交叉。参数化在嵌套方面具有显着的性能优势，以实现气候信息的可比解;然而，以前的SubLIG方案实现对主机MM5模型需要重大修改，禁止其在NCAR支持的MM5中的NCAR支持的社区版本内。通过这种努力，已经解决了软件工程挑战，以合并，并行化和加载 - 平衡PNNL底图方案，最小变为MM5。结果是用于区域气候模拟的有效，可维护的工具，并在开发基于MM5的社区区域气候模型方面的前进。
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