Articles | Volume 10, issue 1
https://doi.org/10.5194/gmd-10-85-2017
https://doi.org/10.5194/gmd-10-85-2017
Development and technical paper
 | 
06 Jan 2017
Development and technical paper |  | 06 Jan 2017

Variational assimilation of land surface temperature within the ORCHIDEE Land Surface Model Version 1.2.6

Hector Simon Benavides Pinjosovsky, Sylvie Thiria, Catherine Ottlé, Julien Brajard, Fouad Badran, and Pascal Maugis

Abstract. The SECHIBA module of the ORCHIDEE land surface model describes the exchanges of water and energy between the surface and the atmosphere. In the present paper, the adjoint semi-generator software called YAO was used as a framework to implement a 4D-VAR assimilation scheme of observations in SECHIBA. The objective was to deliver the adjoint model of SECHIBA (SECHIBA-YAO) obtained with YAO to provide an opportunity for scientists and end users to perform their own assimilation. SECHIBA-YAO allows the control of the 11 most influential internal parameters of the soil water content, by observing the land surface temperature or remote sensing data such as the brightness temperature. The paper presents the fundamental principles of the 4D-VAR assimilation, the semi-generator software YAO and a large number of experiments showing the accuracy of the adjoint code in different conditions (sites, PFTs, seasons). In addition, a distributed version is available in the case for which only the land surface temperature is observed.

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Short summary
The objective of this work is to deliver the adjoint model of SECHIBA obtained with software called YAO, in order to perform 4D-VAR data assimilation. The SECHIBA module of the ORCHIDEE land surface model describes the exchanges of water and energy between the surface and the atmosphere. A distributed version is available when only the land surface temperature is used as an observation, with two examples and documentation.