UPDATED ROUTINE SCHEME IN ORCHIDEE

Meeting of the 18 / 02 / 2019

Present: Agnes Ducharne, Yann Meudesoif, Jan Polcher, Thomas Dubos, Catherine Ottle, Pascal Maugis, Matt Macgrath, Korato Hamada, Philippe Peylin

Excused: Josefine Ghattas, Xudong Zhou

att A/ IMPROVE ROUTINE (Supermesh) TowardsParallelRouting.pdf​: Presentation by Jan P. of a new routing scheme based on the description of the Hydrological units (HTUs) within the grid of ORCHIDEE. Each grid cell of ORCHIDEE may contain several HTUs that flow toward a common point. HTUs may cover several grid cell of ORCHIDEE.

B/ SIMPLE ROUTING: Presentation by Yann M. of the so-called "simple routing" scheme based on the current ORC routing scheme but externalised: the runoff and drainage fluxes calculated on the ORCHIDEE grid are map onto an independant grid representing the basins and their connections. The transport of the flow is done on this new "basin" grid and any return water flux should be interpolated on the ORC grid. This allows flexible parallel implementation.

From the discussion 3 majors directions of work emerge:

• Improving the "simple" scheme of Yann M.: Y.M needs some help to run some tests with a given precipitation field (or directly with a runoff+dranaige flux from an ORC run); This will allow to evaluate the potential of the approach. Note that Yann mentioned

• Define a common target point in terms of routing scheme that the ORCHIDEE group would like to reach. This could combine the advantages of both Yann and Jan approaches. For that a document should be written

• Current works are using a relatively old "basin description" while Jan now has access to a new basin description at 90m (from Dai Yamazaki, based on the MERIT DEM). Jan need some help to work on this new hydrography database