ASSESSMENT OF SOIL MOISTURE THROUGH FIELD MEASUREMENTS AND AMSR-E REMOTE SENSING DATA ANALYSIS OVER KUWAIT DESERT
Keywords:Volumetric Soil Moisture (VSM), AMSR-E, Satellite remote sensing
Field work was conducted 24 times between April 2011 and September 2013 in the KISR (Kuwait Institute of Scientific Research) protected site located at Sulaibiya with the intent of measuring soil moisture at 16 specific locations over a 50 sq. km area. Soil moisture was measured using the thermo-gravimetric method. Soil profile measurement was also conducted up to a depth of 1.2 m to estimate sub-surface soil moisture. The field work estimated soil moisture variation during the wet and the dry seasons and over 16 different locations in the KISR site. The field measurements indicate that the soil moisture varies from 0.11 m3 m-3 in the wet season to less than 0.01 m3 m-3 in the dry season. The standard deviation of the spatial soil moisture variation ranges from 0.02 m3 m-3 in the wet season to less than 0.0009 m3 m-3 in the dry season.
Another study is conducted in this paper using remote sensing data of soil moisture (NASA product) from the Advanced Microwave Scanning Radiometer (AMSR-E) on the Earth Observing System (EOS) Aqua satellite. AMSR-E instrument provides Volumetric Soil Moisture (VSM), Brightness Temperatures and Vegetation Water Content (VWC) during nine years from 2003 to 2011 all over the land mass of the Earth. The AMSR-E derived monthly averaged soil moisture over the Kuwait study area was found to vary between a minimum of 0.06 m3 m-3 in August to a maximum of 0.083 m3 m-3 in January. The standard deviation of the spatial variation of soil moisture ranges from of 0.004 m3 m-3 in August to 0.017 m3 m-3 in January. As the KISR site in Sulaibiya has an area of 50 sq. km area while the AMSR-E pixel area is 625 sq km, a comparison between field measurements and soil moisture comparison is not adequate due to the difference in resolution. However some indications of general trends of soil moisture variations are studied.
Al Jassar, H. K., Rao, K. S & Sabbah, I. 2006. A model for the retrieval and monitoring of soil moisture over desert area of Kuwait, International Journal of Remote Sensing, 27(2), 329-348.
Al Jassar, H. K. & Rao, K. S. 2010. Monitoring of Volumetric Soil Moisture over Kuwait Desert using remote sensing techniques. International Journal of Remote Sensing 31(16):4373-4385.
Halwagy, R. & Halwagy, M. 1974. Ecological Studies on the desert of Kuwait II The Vegetation. Journal University of Kuwait (Sci.) 1, (1974) 87 – 95.
Mladenova, I.E., et. al. 2014. Remote monitoring of soil moisture using passive microwave-based techniques - Theoretical basis and overview of selected algorithms for AMSR-E, Remote Sensing of Environment. 144(0), 197-213.
Njoku, E. G., & Li, L. 1999. Retrieval of land surface parameters using passive microwave measurements at 6–18 GHz. IEEE Transactions on Geoscience and Remote Sensing. 37(1), 79–93.
Njoku, E., et.al. 2003. Soil Moisture retrieval from AMSR-E. IEEE Transactions on Geoscience and Remote Sensing. 41(2), 215-229.
Njoku, E. G. 2004. AMSR-E/Aqua Daily L3 Surface Soil Moisture, Interpretive Parameters, & QC EASE-Grids. Version 2. [ae_land3]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.
Njoku, E. G., & Chan, S. K. 2006. Vegetation and surface roughness effects on AMSR-E land observations. Remote Sensing of Environment. 100(2), 190–199.
NSIDC. 2013. AMSR-E Level 3 Volumetric Soil Moisture Product. http://nsidc.org/data/docs/daac/ae_land3_l3_soil_moisture/data.html (Accessed: July 16th 2013).