Surface Moisture Content Retrieval from Visible/Thermal Infrared Images and Field Measurements

In this study, NOAA/AVHRR satellite was used to estimate the surface temperature and satellite estimated soil
moisture content as input parameters leading to estimate the evapotranspiration over Perak Tengah & Majung
regions in Malaysia. At this stage of the study, the work was focused on the analysis of soil moisture content θ
and surface temperature Ts data acquired from in-situ measurements over two locations: Sitiawan and
University PETRONAS UTP weather stations represents urban area and multiple land cover area respectively.
Throughout the study area, θ was measured using soil moisture probe for Sitiawan and the oven method for
UTP; while Ts data measured using mini thermometers for both stations. Both Ts and θ were measured in three
different near surface depths 5 cm, 10 cm and 15 cm, the θ values were then plotted against Ts in graphical
representations to study the impact of surface temperature on wet soils behavior. A reasonable negative
relationship was noticed among the θ - Ts representation, the relation was agreed with the so called “ Universal
Triangle” method which is being used in the study of soil moisture, vegetation cover and temperature
interaction, particularly over areas with biomass cover. Soil moisture estimation algorithm has been generated
upon the “Universal Triangle” method from the satellite extracted surface temperature, Normalized Difference
Vegetation Index NDVI and the field measured moisture content. Moisture content parameters were calculated,
and then the moisture content algorithm was generated accordingly for the two study locations with three
different “Split-window” algorithms and finally a spatial validation of satellite θ algorithms was conducted for
accuracy assessment.