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The ORCHIDEE model


1. Introduction

Visit the ORCHIDEE's official website
Follow the actualities in developments of ORCHIDEE

The ORCHIDEE model includes 3 components: sechiba, stomate and LPJ (dynamic vegetation). Only the 2 components sechiba and stomate are activated by default. If you are using a coupled configuration with LMDZ, you will need the sechiba component to compute the water and energy balance. You will also need the stomate component to compute the carbon balance. It is possible to deactivate stomate. You will find additional information on how to use ORCHIDEE in libIGCM-supported configurations below.


2. Compile methods in ORCHIDEE

2 compile methods are used in ORCHIDEE depending on the version. Read more about compiling on the ORCHIDEE wiki: https://forge.ipsl.jussieu.fr/orchidee/wiki/Documentation/UserGuide/CompileMethods

Compiling with makeorchidee_fcm

Obsolete : Standard makefiles created based on AA_make and AA_make.gdef

3. Run options

Predefined run options are set in orchidee.card and stomate.card for coupled configurations and in orchidee_ol.card, sechiba.card and stomate.card for offline configurations. Other options not listed in the card can be set directly in the parameter file run.def (for offline run) or orchidee.def(for coupled run).

3.1. Choice of hydrology scheme

Since tag ORCHIDEE_2_1, only a multilayer hydrology scheme called CWRR is implemented. For older versions, the choice of the older 2 bucket scheme Choisnel or the newer multilayer scheme CWRR can be done.

Choose the hydrology scheme in the following way :

3.2. Vegetation map

The vegetation map (PFTmap.nc) can be constant or updated annually. Use the option VEGET_UPDATE=0Y for constant vegetation map and VEGET_UPDATE=1Y to update annually the vegetation map. Note that in previous versions of ORCHIDEE up to revision 2718 on the trunk, including _v5 configurations, the vegetation map was updated in the end of the year with the map for the next coming year. In newer versions and all _v6 configurations, the vegetation map is updated on the first day of the year.

For constant vegetation map, set in orchidee.card (or sechiba.card) VEGET_UPDATE=0Y and set in [InitialStateFiles] the PFTmap.nc file you want to use for the simulation. Note that for constant vegetation map, the vegetation will be read from the restart file. Only if it is not found in the restart file, then the file PFTmap.nc will be read.

To update annually the vegetation map set in orchidee.card (or sechiba.card) VEGET_UPDATE=1Y and set :

3.3. Manage output in _v6 configurations and ORCHIDEE_trunk using XIOS

XIOS is used by default in v6 configurations. In ORCHIDEE_trunk it is possible to activate XIOS output. To do so you need first to compile with XIOS. This is done using gmake with_xios in modipsl/config/ORCHIDEE_OL directory. Before running activate XIOS in orchidee_ol.card by setting XIOS=y. This is the default and only behaviour in coupled _v6 configurations.

The output levels in ORCHIDEE are controlled by the xml files that have to be present during run time. Following files are needed : iodef.xml, context_orchidee.xml, field_def_orchidee.xml and file_def_orchidee.xml. They are stored in the model directory ORCHIDEE/src_xml and in the configuration directory PARAM/. You can see the copy of these files and where they are stored in the orchidee.card or orchidee_ol.card. file_def_orchidee.xml contains a description of predefined files and their variable content. All variables modified by the configuration are marked with _AUTO_. These variables can be changed directly in the file if you want. Otherwise the values set in config.card and/or comp.card will be used. In config.card the choice of output file and frequency is done using the WriteFrequency option in section [SRF] and [SBG] :

Read more in chapter Setup about WriteFrequency.
Read more on the ORCHIDEE wiki about how XIOS is implemented and used in ORCHIDEE : https://forge.ipsl.jussieu.fr/orchidee/wiki/Documentation/UserGuide#Historyoutputfiles

The easiest way to personalise the output is to modify directly in PARAM/file_def_orchidee.xml. You can change the variables marked equal _AUTO_ as you wish. In that case you do not need to change in config.card. You can remove or modify the variables as you need which according to the rules for XIOS.

3.4. Manage output in _v5 configurations using IOIPSL

The model output frequency is configured in

Note that in the _v5 configuration you can not change directly a variable set =_AUTO_ in orchidee.def/run.def. You need to understand how it works through the config.card and comp.card as described above.

4. Deactivate stomate in ORCHIDEE

You can deactivate STOMATE component included by default in all experiments with ORCHIDEE and only run the SECHIBA component. To do so: