ORCHIDEE development for the ROUTING SCHEME

The development of the routing schem

Meeting 08 October 2020

Participant: Jan P., Anthony S. (from Argentina), Agnes D., Catherine O., Olivier B., Jerome S., Yan M., Thomas D., Emmanuel M., Olivier DM, Philippe P.

Jan and Anthony gave a presentation on the recent progresses about the developement of their new routing scheme and the overall procedure to create the necessary input files for the routing scheme in ORCHIDEE: Routage_Jan_Presentation_Oct2020_VAS.pdf Routage_progress_Oct2020​

Note that the developments for this new routing branch are stored under the ipsl gitlab: ​https://gitlab.in2p3.fr/ipsl/lmd/intro/routingpp

Main actions / points discussed are:

• Construction of the Hydrological Transfer Units (HTUs) done offline with the pre-processing routing: Routing_PP
  • Need to test/update routing_PP in order to work with the icosaedric grid (especially for the number of neighbours)
  • Potentially test the "efficiency" of routing_PP with a very large number of processor to gain speed (currently several hours in one node for a regional configuration)
  • Test the impact of the maximum number of HTUs per grid cell on the overall routing scheme
  • The Astropy ​http://spacetelescope.github.io/spherical_geometry/spherical_geometry/user.html spherical geometry package used is probably not the most efficient one.
• Routing scheme in ORCHIDEE
  • NEED to test the intrinsic/numerical properties of the scheme in order to better understand why the results (river discharge for the Amazon river at Obidos) seems to critically depend on the time step in routing and possibly on the number of HTUs per grid box, etc...
  • For that a specific "unitary" test with a pulse of rain (or runoff) should be done. To ease this approach Jan will update the "force_routing" routine in order to perform some tests with allways the same inputs of water.
  • Agnes also suggested to test the properties of the routing scheme with only the "river reservoir"

==> Different tests on the choise of time step, the choise of the HTUs max per grid, the calculation of the topoindex, etc need to be done and discussed together at the next meeting

• Contributions to this work
  • Agnes wants to apply the scheme for the Seine river basin to test its properties
  • Thomas will help with the icosaedric grid to test routing_pp
  • Emannuel will advise on the numerical problems and the physics of the hydrological transfers
  • Yan M. will help with respect to reproducing / understanding the difference between routing the water at the highest resolution (using the original basin description from Hydroshed for instance) and routing the water at a coarser ORCH model resolution.
• Next big step will be to parallelise "routing.f90"
  • Yan will be able to help with XIOS to compute the Halo for each domain, given that the conectivities are pre-calculated by "routing_PP"

==> Next meeting should be in December 2020 or January 2021 with the potential visit of Anthony in France;

Meeting 18 Fevrier 2019

Participant: Jan P., Anthony S., Agnes D., Catherine O., Yan M., Thomas D., Olivier DM, Philippe P.

First meeting to discuss the strategy of the developments of the routing scheme in ORCHIDEE.

• Jan P. presented the approach he is currently following: TowardsParallelRouting.pdf Routage_JanP_Fev2019​
• Yan M. presented a parallele approach which is to perform the routing on a regular lat/lon grid at high resolution, which is easier to parallelise; the scheme then involve to interpolate of the fluxes to the regular grid routage_orchidee_YanM.pdf Routage_YanM_Fev2019​