How are these equations relevant to remotely sensed data? Source: earthsci.org/rockmin/rockmin.html

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1 Lecture 3 How does light give us information about environmental features Revision Select a different scoop from last week Post the key points as a reaction to (need to sign in first) Dr Karen Joyce School of and Life Sciences Bldg Purple Electromagnetic Radiation (EMR) What physical parameters are measured as the basis of remotely sensed images? Controls on variations in EMR reflected, absorbed or transmitted can be explained in the different portions of the EMR spectrum (bands): At the physical level At the atomic level Interactions at both scales are explained and quantified in radiative transfer theories These are equations which convert pixel values to biophysical parameters, and we use these to convert images to maps showing biophysical information. Radiation Transfer and Interaction Pathways for Remote Sensing All remotely sensed data are a result of radiation interactions and transfers Radiative Transfer = Process of EMR being transferred through a medium Radiative Transfer Equations define how EMR is absorbed, reflected and transmitted as it passes through a medium The key to maximising the amount and accuracy of information extracted from remotely sensed data is understanding which radiation transfer and interaction processes to record and analyse How are these equations relevant to remotely sensed data? Source: earthsci.org/rockmin/rockmin.html 3 4 Radiative Transfer Equation for Data in an Image Pixel Total irradiance (E T ) at the earth s surface: E T = E T θ cosθ + E d = [W/m 2.steradian] Where, E = top of atmosphere irradiance T θ = transmissivity of atmosphere cosθ = cosine of solar zenith angle E d = diffuse irradiance R = reflectance or albedo Radiance at the sensor (L s ): L T = 1/π. R (E T θ cosθ + E d ) Additive path radiance = L P Total radiance at sensor L s = L T + L P E E d E T θ R L S L p L T Choose a topic The Atmosphere Vegetation Soils / rock Benthic habitats Your Job Part 1 Identify the physical, chemical, and biological components relevant to your topic Post to one of the following:

2 Vegetation Radiative Transfer Vegetation Scales Light interactions with vegetation are controlled at several scales Within leaf: Photosynthetic processes Action spectrum of photosynthesis Photosynthetic + non-photosynthetic 1 pigments 8 Chlorophyll b content 6 Carotenoids Self-defense/regulatory mechanisms 4 2 Leaf internal and external structures Estimated absorption (%) Chlorophyll a Wavelength (nm) Rate of photosynthesis (as % of rate at 67nm) Leaf Internal (structure, chemistry, processes) Form/morphology Orientation Coating Canopy Density and arrangement of leaves Crown form and layering Stand Structural properties Topography/microclimate Biomass Community 7 8 Radiation Transfer and Interactions -interactions: Air- interface + atmosphere column Substrate features (sediment, benthic flora and fauna) -column: Absorption and Scattering Suspended and Dissolved matter Key controls: Surface roughness Organic matter Inorganic Matter Depth Substrate type Mineral and Soil Radiation Transfer Minerals Similar controls on interactions as atmospheric gases Atomic level interactions of light with different minerals is unique due to their structure Results in distinctive mineral absorption spectra Source of minerals data: Soils - Mineral content (e.g. iron oxide) - Organic content (e.g. leaf litter) - Roughness / texture (sand, silt, clay) - Moisture content 9 1 Aquatic Vegetation - Coral Your Job Part 2 Choose a different topic The Atmosphere Vegetation Soils / rock Benthic habitats Graph source A: Hochberg, E. J., M. J. Atkinson and S. Andréfouët (23). "Spectral reflectance of coral reef bottom-types worldwide and implications for coral reef remote sensing." Remote Sensing of Environment 85(2): Identify the potential remote sensing applications Post to one of the following:

3 Forest Disturbance / Edge Effect Mapping Biophysical Inverse Models Foliar Chemistry Tree-Crown Delineation Figure 24b. ETM Band 4 vs Canopy cover Tree-Crown Delineation & Identification Reflectance 1. y = Ln(x) R2 = TM4 4. Log. (TM4) CASI image Canopy cover (% cover) High Predicted Tree Density for Curtain Fig Study Site Chl-a N W # E S Low High Predicted Tree Density Non Forest -2 trees/ha 2-4 trees/ha 4-6 trees/ha 6-8 trees/ha 8-1 trees/ha 1-12 trees/ha trees/ha trees/ha trees/ha 8-2 trees/ha >2 trees/ha 5 1 Metres Map composed by Tim O'Donnell Projected to UTM (WGS 84) Data: Landsat ETM, July 2 (Copyright ACRES) Values of basal area modelled using Landsat ETM data. water Landsat 7 Enhanced Thematic Mapper Scene: Cairns Image Date: 22 July 2 Copyright: ACRES 2 Display: Red = NIR band Green = Red Blue = Green Low Source: T. O Donnell Global Ocean Colour and Productivity Monitoring Source: J.Nightingale Source: P.Scarth Source: C.Ticehurst/A.Held Exploration Geology Tonopah Seawifs 8-year March average of Chlorophyll a concentration Design your own globe: r.gsfc.nasa.gov/cgi/biosphere_globes.pl West-central Nevada Goldfield ASTER SWIR RGB saturation stretched Cuprite Source: ASTER Applications to Earth Science Anne Kahle, Jet Propulsion Laboratory 15 ASTER SWIR Data for Cuprite Mapping Sem Lecture 3 Source: ASTER Applications to Earth Science Anne Kahle, Jet Propulsion Laboratory 17 GEOM2/7 Remote Sensing of Environment 16 Ozone Hole Watch

4 Volcanic Gas & Ash Your Job Part 3 Ash and Aerosols Choose a different topic The Atmosphere Vegetation Soils / rock Benthic habitats Sulphur Dioxide Identify the relevant wavelengths and interactions Post to one of the following: Source: 2 Foliar Chemistry and Reflectance Based Spectral Signatures Carotenoids, Xanthophylls Chlorophyll a,b Cellular Scattering Sugar Starch Protein Starch Lignin Protein Cellulose Sugar Cellulose Lignin Source: A.Held, CSIRO Seawifs Image Based Spectral Signatures 1km Each pixel contains : 1: 412nm 2: 443nm 3: 49nm 4: 51nm 5: 555nm 6: 67nm 7: 765nm 8: 865nm Estimated absorption (%) Action spectrum of photosynthesis Chlorophyll b Carotenoids Chlorophyll a Wavelength (nm) Chl a (mg/m3) = R(49nm) R(555nm) Rate of photosynthesis (as % of rate at 67nm) absorption m -1 Absorption and Scattering of Pure wavelength(nm) absorption(left axis) scattering(right axis) Depth Effects scattering m -1 Band 43 - NIR - red Band 1- blue Landsat ETM Scene, Heron Reef May,

5 Factor Atmospheric Conditions Stage of growth (for vegetation) Reflective and emissive properties Controls on EMR Interactions Spectral Signature Variation Presence or absence of water vapour in the atmosphere Presence or absence of gases, smoke and dust particles in the atmosphere Changing appearance depending upon the stages of growth Changes in health or varying nutrients availability Incidence of diseases Variation in spatial properties (e.g. density of plants, pattern of distribution) Variation in thermal properties Who, Why, What, Where, When, How Subject Considerations, Impediments Site environmental Conditions Viewing Condition Variation in moisture availability Variation in site fertility Variation in sun angles Variation in sensor viewing angle Variation in altitude of the viewing platform Characteristics, Availability / Schedule Subject General location Time of disappearance (and time elapsed) Weather conditions Size, shape, colour, temperature of missing object Contrast of missing object with its environment Cloud cover Obscuring features (vegetation, water bodies) Subject movement (wind, currents) Subject Spectral capability Spatial detail Spatial extent Overpass frequency $$ 2 km Worldview-2 Panchromatic.5 m GSD

6 59.6 m 7.6 m 6 m 8.6 m Total area earth = 51,72,km 2 Total area MCG = 2,m 2 Total area plane = 934 m 2 Size of relative equivalent feature =?? Diameter of the object to find within the MCG =.2 mm! Could you find a grain of cous cous in the MCG? 31 6