TY - JOUR
T1 - Diurnal emissivity dynamics in bare versus biocrusted sand dunes
AU - Rozenstein, Offer
AU - Agam, Nurit
AU - Serio, Carmine
AU - Masiello, Guido
AU - Venafra, Sara
AU - Achal, Stephen
AU - Puckrin, Eldon
AU - Karnieli, Arnon
N1 - Funding Information:
The project was funded by the Israeli Ministry of Science and Technology . Offer Rozenstein was supported by the Pratt Foundation . We thank Prof. Yosef Ashkenazy of the Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, for sharing data from the meteorological station at the Nizzana research site.
Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2015/2/5
Y1 - 2015/2/5
N2 - Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in emissivity, as detected from space, are larger for areas mostly covered by biocrusts (composed mainly of cyanobacteria) than for bare sand areas. The LSE dynamics were monitored from geostationary orbit by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) over a sand dune field in a coastal desert region extending across both sides of the Israel-Egypt political borderline. Different land-use practices by the two countries have resulted in exposed, active sand dunes on the Egyptian side (Sinai), and dunes stabilized by biocrusts on the Israeli side (Negev). Since biocrusts adsorb more moisture from the atmosphere than bare sand does, and LSE is affected by the soil moisture, diurnal fluctuations in LSE were larger for the crusted dunes in the 8.7. μm channel. This phenomenon is attributed to water vapor adsorption by the sand/biocrust particles. The results indicate that LSE is sensitive to minor changes in soil water content caused by water vapor adsorption and can, therefore, serve as a tool for quantifying this effect, which has a large spatial impact. As biocrusts cover vast regions in deserts worldwide, this discovery has repercussions for LSE estimations in deserts around the globe, and these LSE variations can potentially have considerable effects on geophysical models from local to regional scales.
AB - Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in emissivity, as detected from space, are larger for areas mostly covered by biocrusts (composed mainly of cyanobacteria) than for bare sand areas. The LSE dynamics were monitored from geostationary orbit by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) over a sand dune field in a coastal desert region extending across both sides of the Israel-Egypt political borderline. Different land-use practices by the two countries have resulted in exposed, active sand dunes on the Egyptian side (Sinai), and dunes stabilized by biocrusts on the Israeli side (Negev). Since biocrusts adsorb more moisture from the atmosphere than bare sand does, and LSE is affected by the soil moisture, diurnal fluctuations in LSE were larger for the crusted dunes in the 8.7. μm channel. This phenomenon is attributed to water vapor adsorption by the sand/biocrust particles. The results indicate that LSE is sensitive to minor changes in soil water content caused by water vapor adsorption and can, therefore, serve as a tool for quantifying this effect, which has a large spatial impact. As biocrusts cover vast regions in deserts worldwide, this discovery has repercussions for LSE estimations in deserts around the globe, and these LSE variations can potentially have considerable effects on geophysical models from local to regional scales.
KW - Biocrust
KW - LWIR
KW - SEVIRI
KW - Sand dunes
KW - Thermal remote sensing
KW - Water vapor adsorption
UR - http://www.scopus.com/inward/record.url?scp=84911861553&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2014.11.035
DO - 10.1016/j.scitotenv.2014.11.035
M3 - Article
AN - SCOPUS:84911861553
SN - 0048-9697
VL - 506-507
SP - 422
EP - 429
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -
