MESH: The MEC-Surface & Hydrology System
MESH Origins and Development
The process began by linking land-surface and atmospheric models, through the development of Land Surface Schemes (LSS), which have become increasingly sophisticated; the Canadian LSS, CLASS, is a particularly good example. More recently, LSS models have been incorporated into hydrological models, to provide stand-alone Hydrology-Land-Surface Scheme (HLSS) systems. The next step has been to link atmospheric and hydrological models: when an HLSS is incorporated into an atmospheric model, the result is a fully-coupled system. However, most of these efforts have led only to the development of modelling tools suited to the needs of researches; the use of these architectures in operational hydrometeorological forecasting systems has been limited.
To overcome this obstacle, the Numerical Weather Prediction Research Group at Environment and Climate Change Canada developed the Modélisation Environmentale Communautaire (Community Environmental Modelling System) or MEC: this provides a flexible framework within which models representing different components of the earth system may be connected, with the principal goal of supporting the use of these coupled models to generate operational forecasts.
Scientists at Environment and Climate Change Canada's National Hydrological Research Centre and the Centre for Hydrology have used MEC as the foundation for a coupled land-surface and hydrological model known as MEC-Surface & Hydrology, or MESH. This was originally developed from the University of Waterloo's WATCLASS, which linked CLASS with an existing hydrological model geared towards flood-forecasting, WATFLOOD.
The system has been implemented both as an HLSS, integrating CLASS and hydrological modelling components, with atmospheric forcings reads from supplied files (Standalone MESH), and as a fully-coupled system which runs in conjunction with an atmospheric model (MEC-MESH), the latter being furnished by the Global Environmental Multiscale Model, GEM.
More detailed information is also available in the following paper:
MESH Benefits and Advantages
This not only means that researchers and end-users may use and modify it freely, but also that MESH will continue to improve over the years, benefitting from improvements made to the modelling system for both research-related and operational purposes.
The development of MESH ties directly into a series of existing projects and programs in Canada, including
The system permits several different surface models to coexist within the same modelling framework, enabling ready comparison of the outputs they generate from exactly the same forcings, interpolation procedures, grid, time-period, time-step, and other specifications. The coupler may also be used to link models running on different grids, and potentially on different time steps. The current implementation includes a choice of three land-surface schemes:
One of the primary goals set for MESH is to improve the description and quantification of the importance of sub-grid variability; to achieve this, CLASS may be configured to run on a number of different HRUs or tiles within each gridcell, allowing subgrid landscape variability to be taken into account. MESH then permits the routing of water and transfers of energy both between tiles within a grid, and between grids.
How to obtain MESH
If you have any enquiries relating to MESH, please contact Bruce Davison of Environment and Climate Change Canada's National Hydrological Research Centre in Saskatoon. We have also established a MESH forum to provide a vehicle for feedback and discussion, and further information is available on the MESH wiki.