Thermal remote sensing BY Hariom Ahlawat

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thermal remote sensing

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  • 1. AIM TO ACQUINT THE CLASS WITH CONCEPTS OF THERMAL REMOTE SENSING
  • 2. CONTENTS INTRODUCTION PRINCIPLES OF THERMAL REMOTE SENSING THERMAL SENSORS APPLICATIONS
  • 3. INTRODUCTION
  • 4. REMOTE SENSING Remote sensing is an art and science of acquiring info about an object of interest without coming in physical contact with it.
  • 5. THERMAL REMOTE SENSING Thermal remote sensing is based on the measuring of EM radiation in the infrared region of spectrum. Most commonly used intervals are 3-5 micro-meter and 8-14 micro-meter
  • 6. Thermal IR and atmospheric window Landsat 7 Band 7 Landsat 7 Band 6 Global Warming! Thermal energy emitted from the Earth is trapped by CO2, H2O, and O3.
  • 7. CERES—Cloud-Earth Radiant Energy System
  • 8. PRINCIPLES OF THERMAL REMOTE SENSING
  • 9. Electromagnetic Radiance (EMR) EMR – Energy emitted by the objects of which absolute temperature is above zero. The magnitude and spectral range of the emitted EMR are governed by the material’s: Temperature, and Emissivity
  • 10. Review of Radiation Laws All objects at temperature above absolute 0oK emit (273.59oC, -459.67oF) Stefan-Boltzmann law: W = T4 W-total emitted radiation -a constant, T-temperature in oK The total emitted radiation from a blackbody is proportional to the fourth power of its absolute temperature
  • 11. Radiation Laws ► Wien's displacement law: = 2,897.8/T -peak wavelength, T-temperature in oK ► As temperature of objects increases, the wavelength of peak emittance becomes shorter
  • 12. Radiation Laws ► Emissivity: e = M/Mb e-emissivity M-emittance of a given object Mb-emittance of blackbody e = 1 (blackbody) e = 0 (whitebody, perfect reflector) ► The ratio between the emittance of a given object and that of blackbody at the same temperature
  • 13. Emissivity of Common Materials Clear water 0.98-0.99 Wet snow 0.98-0.99 Human skin 0.97-0.99 Rough ice 0.97-0.98 Vegetation 0.96-0.99 Wet soil 0.95-0.98 Asphalt concrete 0.94-0.97 Brick 0.93-0.94 Wood 0.93-0.94 Basalt rock 0.92-0.96 Dry mineral soil 0.92-0.94 paint 0.90-0.96 Dry vegetation 0.88-0.94 Dry snow 0.85-0.90 Granite rock 0.83-0.87 Glass 0.77-0.81 Sheet iron (rusted) 0.63-0.70 Polished metals 0.16-0.21 Aluminum foil 0.03-0.07 Highly polished gold 0.02-0.03
  • 14. Water, Ice and Snow Water, ice, and snow generally have a high emissivity, 0.94 to 0.99, across the thermal infrared region. Snow is unusual in that it has a high reflectance in the solar (visible) region where most of the downwelling energy is during the day, and a very high emissivity in the thermal region. Water Ice Snow
  • 15. Soil and Minerals Soil, rocks, and Minerals show strong spectral features between 8 and 10 microns that depend on the grain size. Soil signature in the 3 to 5μm region depends on the water and organic content. The dryer, purer soils have lower emissivities in this region.
  • 16. Vegetation Green vegetation typically has a very high emissivity because it contains water. Senescent (dry) vegetation has a more variable emissivity, especially in the 3 to 5μm region, which depends on the type and structure of the cover type, the dryness, etc.
  • 17. Man-made material Manmade materials such as polished metals have among the lowest emissivity values, can be made less than 0.01 (better than 99% reflecting). “Rocky” materials such as asphalt and brick are high and range from 0.90 to 0.98
  • 18. (Wikipedia – Infrared)
  • 19. Thermal sensors
  • 20. THERMAL SENSORS TIROS (Television IR Operational Satellite), launched in 1960 GOES (Geostationary Operational Environmental Satellite), TIR at 8km spatial resolution, full-disk of Earth, day and night HCMM (Heat Capacity Mapping Mission), launched in 1978600m spatial resolution, 10.5 – 12.6 micron range CZCS (Coastal Zone Color Scanner) on Nimbus 7, launched in 1978, for SST (sea surface temperature). AVHRR (Advanced Very High Resolution Radiometer), 1.1 and 4 km TIR bands TIMS (Thermal Infrared Multispectral Scanner), Airborne, 6 bands ATLAS (Airborne Terrestrial Applications Sensor), 15 bands Landsat 4,5,7; Band 6- 10.4 – 12.5 m, 120 m (4,5), 60 m (7). ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) on Terra, 5 bands 8.125-11.65 micron range (14 total)
  • 21. Applications
  • 22. Application Areas Surface temperature detection Camouflage detection Fire detection and fire risk mapping Evapotranspiration and drought monitoring Estimating air temperature Oil spill monitoring Water quality monitoring Volcanic activity monitoring Urban heat island analysis
  • 23. Mars Hematite detected by TES
  • 24. Typical IR imagery of Heat Loss in Residential Structures 43.0°F 40 35 Furnace Vent Vent Duct 30 25 24.0°F
  • 25. Energy Gain (Floor Leak) Missing Insulation in Vaulted Ceiling Area Heat Loss Moisture Heat Loss
  • 26. Typical Institutional Building Heat Loss 46.6° 50.9°F 50 48 46 44 42 40 38 37.7°F Typical Air Leak Patterns 37.3° 5
  • 27. *>64.4°F 60.0 55.0 50.0 45.0 Air Leakage from noninsulated areas and window frames.
  • 28. Processing thermal images Major issues Moisture absorption in atmosphere Mixed ground objects Some visualization techniques False color composite Level slicing
  • 29. Sea-surface temperature, June 22, 2000
  • 30. Ocean surface temperature from MODIS 47
  • 31. QUESTIONS PLEASE !!
  • 32. Thank You
  • 33. Thank You