Application: Lithosphere Artists impression of Spot 5Applications ! Earth Structure (gravity and topography) ! Geothermal Heat Flux ! Soil Characteristics  composition  Moisture content/Thermal inertia ! Mineral and Rock Classification  AVIRIS and hyperspectral imagery  Multispectral and panchromatic ! GeomorphologyGravity (GRACE) Elevation (SRTM)Mapping Geothermal Heat FluxSoil Grain Size and Texture  The average diameter of grains in a soil horizon is one of the major variables used to identify the taxonomy of a soil  There are 3 universally recognized soil grain size classes: sand, silt and clay  Sand: between 0.05 and 2.0 mm, large air spaces, rapid drainage of water  Silt: between 0.002 and 0.05 mm, enhance movement and retention of soil capillary water  Clay: < 0.002 mm, carry electrical charges which hold ions of dissolved mineralsThree soil particle size scales to classify soil based on diameterSoil Texture Triangle ! Proportion of sand, silt and clay in a soil (or horizon), usually calculated as % weight for each type of particle ! Soil texture is the relative proportion of sand, silt and clay ! Define soil types based on the % contributionFactors Influencing Soil Reflectance ! Mineral composition ! Soil moisture ! Organic matter content ! Texture and roughness ! SalinitySoils: Mineral Composition ! Affects the visible, NIR, and thermal portions of the reflectance spectrum ! Increasing reflectance from visible to NIR ! Iron and clays are detectable  oxidized iron appear red  reduced iron appear green-blue  clays affect water and OH+ absorption featuresBasic Dry Soil Spectrum Key characteristic of soil spectrum: increasing reflectance with increasing wavelength through the visible, near and mid infrared portions of the spectrumApplication: Remote Sensing of Swelling Clay Soils Different types of clays can be identified spectroscopically thanks to their characteristic absorption bands around 2.2 umLand Surfaces are often a mixture of soils that may have similar spectral signatures! spectra for hundreds of geological materials can be found at: http://speclab.cr.usgs.gov/spectral.lib04/spectral-lib.desc+plots.htmlAVIRIS: Airborne Visible InfraRed Imaging Spectrometer ! AVIRIS provides calibrated images of the upwelling spectral radiance in 224 contiguous spectral channels with wavelengths from 400 to 2500 nanometers (nm). 224 Stacked images in very narrow spectral bandsFe (Iron)-bearing mineral map (0.35-1.35 micron spectral region) in the Antelope Range, Nevada derived from Analysis of AVIRIS data Created by the USGSSoil Characteristics  Soil is unconsolidated material at the surface of the Earth that serves as a natural medium for growing plants  Soil is a mixture of inorganic mineral particles and organic matter of varying size and composition  Particles make up about 50% of the soil’s volumeSoils: Soil Moisture ! Water is a strong absorber, so soils with more moisture will be darker over most of the VNIR and SWIR portions of the spectrum than drier soils ! The depths of the water absorption bands at 1.4, 1.9 and 2.7 µm can be used to estimate soil moistureSoils: Soil Moisture and Texture ! Since clayey soil holds water more tightly than sandy soil, the water absorption features are more prominent in clayey soils ! All soils that have a moderate to high proportion of clay-size particles exhibit strong hydroxyl absorption bands at 1.4 and 2.2 µm ! AVIRIS can be useful for quantifying these absorption featuresSoil Moisture from Thermal Sensors ! Water has a higher thermal capacity than soil and rock ! Moist soils will change in temperature more slowly than dry soils ! Apparent thermal inertia can be used to distinguish dry from moist soilsSoil Moisture from Thermal Sensors This airborne thermal imagery (Daedalus) is taken at nighttime. If we had a daytime image to compare it to, we could see the amount of change in temperature and make inferences on the soil moisture content (less change = more moisture)Soils: Organic Matter ! Organic matter affects soil color, heat capacity, water holding capacity, nutrient exchange, structure, and vulnerability to erosion ! Dark color generally associated with high organic matter ! Landsat TM bands 5 and 6 have negative correlation with organic matterSoils: Organic Matter ! Organic matter is a strong absorber of EMR, so more organic matter leads to darker soils (lower reflectance curves)Soils: Organic Matter ! Organic matter content in the Santa Monica mountains mapped using AVIRIS (Palacios-Orueta et al., 1999)Pass 1: Before Motion Pass 2: After Motion Phase Difference Application Earthquakes: Repeat Pass Inteferometric SARInterferogram Showing Displacement from Landers Earthquake in 1992 One cycle of color corresponds to 2.8 cm of displacementGeomorphology: Landforms ! Typically identified by shape, not spectral properties ! Use shadowing to identify features  optical (VIS/NIR imagery)  synthetic aperture radar: useful in regions frequent with cloud coverGeomorphology: Eolian landforms Star dunes from Landsat TM Longitudinal dunes from ASTER (w/clays between dunes) Grand Erg Orientale, a Sahara Desert member here at the border of Algeria with Libya. These appear as roughly equi-sided hills rising in some cases more than 100 m above the sandy base: Empty Quarter dunes (longitudinal type) in southern Saudi Arabia. In the version below, dunes are bright yellow and brown whereas the blue relates to the spectral response of interdune clays and silts.Geo-morphology: Igneous landforms Stratovolcano, Mount Rainier, WashingtonTectonic Landforms Colorado Rocky Mountains from Landsat TM (band 4) Canadian Rocky Mountains from Radarsat Shaded Relief from Shuttle Radar Topography MissionGeomorphology: Fluvial Landforms ! Dendritic networks are easily recognized Radar image of dendritic river network in east-central ColombiaGeomorphology: Shoreline Landforms MISR image of Mississippi Delta (birdsfoot delta) multi-angle composite false color composite true color compositeGeomorphology: Glacial Landforms ASTER image of receding glaciers in Bhutan (note lakes forming at glacier termini)Geomorphology: Glacial Landforms Landsat TM image of “fluting” caused by massive glacial erosion of bedrock on the Canadian