Combining the triangle method with thermal inertia to estimate regional evapotranspiration: applied to MSG-SEVIRI data in the Senegal River basin

TY - JOUR

T1 - Combining the triangle method with thermal inertia to estimate regional evapotranspiration

T2 - applied to MSG-SEVIRI data in the Senegal River basin

AU - Stisen, Simon

AU - Sandholt, Inge

AU - Nørgaard, Anette

AU - Fensholt, Rasmus

AU - Jensen, Karsten Høgh

N1 - Online - corrected proof version (11.1.2008)

PY - 2008

Y1 - 2008

N2 - Spatially distributed estimates of evaporative fraction and actual evapotranspiration are pursued using a simple remote sensing technique based on a remotely sensed vegetation index (NDVI) and diurnal changes in land surface temperature. The technique, known as the triangle method, is improved by utilizing the high temporal resolution of the geostationary MSG-SEVIRI sensor. With 15 min acquisition intervals, the MSG-SEVIRI data allow for a precise estimation of the morning rise in land surface temperature which is a strong proxy for total daytime sensible heat fluxes. Combining the diurnal change in surface temperature, dTs with an interpretation of the triangular shaped dTs-NDVI space allows for a direct estimation of evaporative fraction. The mean daytime energy available for evapotranspiration (Rn-G) is estimated using several remote sensors and limited ancillary data. Finally regional estimates of actual evapotranspiration are made by combining evaporative fraction and available energy estimates. The estimated evaporative fraction (EF) and actual evapotranspiration (ET) for the Senegal River basin have been validated against field observations for the rainy season 2005. The validation results showed low biases and RMSE and R2 of 0.13 [-] and 0.63 for EF and RMSE of 41.45 W m-2 and R2 of 0.66 for ET.

AB - Spatially distributed estimates of evaporative fraction and actual evapotranspiration are pursued using a simple remote sensing technique based on a remotely sensed vegetation index (NDVI) and diurnal changes in land surface temperature. The technique, known as the triangle method, is improved by utilizing the high temporal resolution of the geostationary MSG-SEVIRI sensor. With 15 min acquisition intervals, the MSG-SEVIRI data allow for a precise estimation of the morning rise in land surface temperature which is a strong proxy for total daytime sensible heat fluxes. Combining the diurnal change in surface temperature, dTs with an interpretation of the triangular shaped dTs-NDVI space allows for a direct estimation of evaporative fraction. The mean daytime energy available for evapotranspiration (Rn-G) is estimated using several remote sensors and limited ancillary data. Finally regional estimates of actual evapotranspiration are made by combining evaporative fraction and available energy estimates. The estimated evaporative fraction (EF) and actual evapotranspiration (ET) for the Senegal River basin have been validated against field observations for the rainy season 2005. The validation results showed low biases and RMSE and R2 of 0.13 [-] and 0.63 for EF and RMSE of 41.45 W m-2 and R2 of 0.66 for ET.

KW - Faculty of Science

KW - overflade temperatur

KW - MSG SEVIRI

KW - Triangle method

KW - Thermal inertia

KW - NDVI

KW - Surface temperature

KW - Evapotranspiration

KW - Evaporative fraction

KW - Remote sensing

U2 - 10.1016/j.rse.2007.08.013

DO - 10.1016/j.rse.2007.08.013

M3 - Journal article

SN - 0034-4257

VL - 112

SP - 1242

EP - 1255

JO - Remote Sensing of Environment

JF - Remote Sensing of Environment

IS - 3

ER -