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Relation between Seasonally Detrended Shortwave Infrared Reflectance Data and Land Surface Moisture in Semi-Arid Sahel

Author:
  • Jorgen L. Olsen
  • Pietro Ceccato
  • Simon R. Proud
  • Rasmus Fensholt
  • Manuela Grippa
  • Eric Mougin
  • Jonas Ardö
  • Inge Sandholt
Publishing year: 2013
Language: English
Pages: 2898-2927
Publication/Series: Remote Sensing
Volume: 5
Issue: 6
Document type: Journal article
Publisher: MDPI AG

Abstract english

In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue. In this study we explored the potential of using reflectance data in the Red, Near Infrared (NIR), and Shortwave Infrared (SWIR) spectral regions for detecting short term variations in land surface moisture in the Sahel, by analyzing data from three test sites and observations from the geostationary Meteosat Second Generation (MSG) satellite. We focused on responses in surface reflectance to soil-and surface moisture for bare soil and early to mid-growing season. A method for implementing detrended time series of the Shortwave Infrared Water Stress Index (SIWSI) is examined for detecting variations in vegetation moisture status, and is compared to detrended time series of the Normalized Difference Vegetation Index (NDVI). It was found that when plant available water is low, the SIWSI anomalies increase over time, while the NDVI anomalies decrease over time, but less systematically. Therefore SIWSI may carry important complementary information to NDVI in terms of vegetation water status, and can provide this information with the unique combination of temporal and spatial resolution from optical geostationary observations over Sahel. However, the relation between SIWSI anomalies and periods of water stress were not found to be sufficiently robust to be used for water stress detection.

Keywords

  • Physical Geography
  • soil moisture
  • vegetation
  • water stress
  • Earth observation
  • MSG SEVIRI
  • SIWSI
  • NDVI
  • Sahel
  • drought

Other

Published
  • ISSN: 2072-4292
E-mail: jonas [dot] ardo [at] nateko [dot] lu [dot] se

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Dept of Physical Geography and Ecosystem Science

+46 46 222 40 31

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Dept of Physical Geography and Ecosystem Science

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Department of Physical Geography and Ecosystem Science
Lund University
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S-223 62 Lund
Sweden

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