Variational assimilation of land surface temperature within the ORCHIDEE Land Surface Model Version 1.2.6
- 1Sorbonne University, UPMC Univ Paris 06 CNRS-IRD-MNHN, LOCEAN Laboratory 4 place Jussieu,75005 Paris, France
- 2Inria Paris, 75012 Paris, France
- 3UVSQ, 78035 Versailles, France
- 4Laboratoire CEDRIC, Conservatoire National des Arts et Métiers, 292, rue Saint Martin, 75003 Paris, France
- 5Laboratoire des Sciences du Climat et de l'Environnement (LSCE), UMR 8212, CNRS-CEA-UVSQ, Orme des Merisiers, 91191 Gif-sur-Yvette, France
- 6CLIMMOD Engineering, Orsay, France
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.