Vol. 8, No. 2, 187-193, 2009

Accurate assessment of land surface thermal emissivity
Maria Mira, Vicente Caselles, Enric Valor and César Coll

The emissivity of natural surfaces is a required parameter in high accuracy land surface temperature (LST) determinations. Then, it is of great importance to know how thermal infrared (TIR) emissivity changes with the different factors. Soil type influence on emissivity is well known from experimental studies, whereas the effect of soil moisture (SM) on emissivity is one of the pending issues in thermal remote sensing. It is seen that the SM variation may cause a high systematic error in emissivity, e.g., about +0.1 in emissivity for an increase from 0.04 to 0.10 g/cm3 in SM for sandy soils. This study reveals a common emissivity increase with soil water content, higher for larger sand content and in the 8 to 9 μm range, but always significant considering the experimental uncertainty (δε~±0.5%). The emissivity increase is understood because of both the quartz contribution to decrease the emissivity of the material chiefly between 7.7 and 9.7 μm, and the decrease of the reflectivity by the water film on the soil particles. Emissivity-SM relationships were obtained with the aim of using them together with SM estimates from remotely sensed data in order to improve the TIR emissivity estimations and thus, the LST determination. Furthermore, the study showed the possibility of retrieving SM from TIR emissivities with a standard estimation error of about ±0.08 m3m-3, when considering the OM content.

View Full Text (pdf file, 200 kB) previous page
Submitted: 05 June 2009
Revised: 03 Dec 2009
Accepted: 04 Dec 2009
Published: 18 Dec 2009
Responsible editor: Bogdan Zagajewski

Mira M, V Caselles, E Valor & C Coll, 2009. Accurate assessment of land surface thermal emissivity. EARSeL eProceedings, 8(2): 187-193


EARSeL European Association of Remote Sensing Laboratories, Strasbourg, France


BIS Library and Information System, Carl von Ossietzky University of Oldenburg


ISSN 1729-3782