OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

Implementation of a satellite-based prognostic daily surface albedo depending on soil wetness : impact study in SURFEX modelling platform over France

Liu, Siliang. Implementation of a satellite-based prognostic daily surface albedo depending on soil wetness : impact study in SURFEX modelling platform over France. PhD, Institut National Polytechnique de Toulouse, 2014

[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
6MB
[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
5MB

Official URL: http://ethesis.inp-toulouse.fr/archive/00002733/

Abstract

The main objective of the thesis is to develop a prognostic surface albedo of the visible spectrum and near infrared and assess its impact on the energy balance and hydrology in the modelling platform of SURFEX. First, a statistical approach has generated a global climate albedo product at 0.05 ° for bare soil and vegetation using multiple years 8 -day MODIS onboard TERRA and AQUA satellites heliosynchronous data. Then, an original method has been developed to reduce temporal resolution of MODIS 500m albedo to daily. The result is validated against in situ measurements as well as daily albedo from geostationary satellite MSG / SEVIRI Land SAF project after projection of MODIS. Then a method of separating albedo of bare soil and vegetation is applied to the datasets of the two satellite systems. Using a threshold of vegetation cover, a calibration of the albedo bare soil with measured soil moisture is derived from 2007 to 2010 for 12 SMOSMANIA stations over southwestern France. We derived a parameterization of the albedo of bare soil with moisture to make the climate changing albedo. The albedo and simulated happens to be very well correlated with observations from space, which helps to explain the albedo variations at very short notice. To change seasonally albedo, a simple parameterization of canopy albedo derived from detailed radiative transfer code PROSAIL is used. The variables are the albedo of the sheet, canopy geometry and chlorophyll content. In order to be sensitive to chlorophyll, the study is based on an albedo at 560 nm. The theoretical approach is validated with MODIS satellite data for the site Majadas (Spain). The next step is to conduct an impact study of this new predictive albedo on the energy balance and hydrology within SURFEX over France and highlighting effects on temperature. More preliminary restricted to a SMOSMANIA station, an assimilation scheme is developed for surface albedo together with the leaf area index LAI and surface moisture. This effects an improvement in the prescribed LAI at the beginning of crop growth.

Item Type:PhD Thesis
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Laboratory name:
Research Director:
Roujean, Jean-Louis
Statistics:download
Deposited On:02 Dec 2014 22:58

Repository Staff Only: item control page