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Atmospheric Radiation GCC Summer School Montreal - August 7, 2003

Atmospheric Radiation GCC Summer School Montreal - August 7, 2003. Glen Lesins Department of Physics and Atmospheric Science Dalhousie University Halifax glen.lesins@dal.ca. Outline. Introductory concepts Radiation and Climate Radiative Transfer Theory Remote Sensing. Credits.

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Atmospheric Radiation GCC Summer School Montreal - August 7, 2003

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  1. Atmospheric RadiationGCC Summer SchoolMontreal - August 7, 2003 Glen Lesins Department of Physics and Atmospheric Science Dalhousie University Halifax glen.lesins@dal.ca

  2. Outline • Introductory concepts • Radiation and Climate • Radiative Transfer Theory • Remote Sensing

  3. Credits • K.N. Liou, An Introduction to Atmospheric Radiation, 2nd Ed., 2002 • Web Lecture Notes by Prof. Irina Sokolik, http://irina.colorado.edu/teaching.htm

  4. Global Annual Energy Balance Kiehl and Trenberth (1997); IPCC (2001)

  5. What is the Solar Constant? • 1366 W m-2 • How constant? • Earth’s orbit and tilt (annual) • Sunspot cycle (11 years) • Longer time variations

  6. Solar Irradiance Variation from ACRIM

  7. http://science.nasa.gov/headlines/images/sunbathing/sunspectrum.htmhttp://science.nasa.gov/headlines/images/sunbathing/sunspectrum.htm

  8. Solar vs. Terrestrial Radiation

  9. Absorption of Radiation by Gases 1. Ionization/Dissociation - UV 2. Electronic Transition - UV 3. Vibrational/Rotational Transition - Visible/IR 4. Pure Rotational - IR

  10. Transmission through the Atmosphere Terrestrial Solar IR Window

  11. Radiative Interactions - Dipole Transitions

  12. Vibrational Modes

  13. + + – •• •• •• O O O O O O •• •• •• •• •• •• •• •• •• Ozone (O3) Electrostatic potentialmap shows both endoxygens are equivalentwith respect to negativecharge. Middle atomis positive. www.facstaff.oglethorpe.edu/mwolf/PowerPoint/ CareyOrgPP/sections1st/Chapter%201bx.ppt

  14. Absorption by Gases

  15. Solar Irradiance

  16. Particle Size Wavelength Scattering of Radiation Size Parameter, a a = 2pr/l

  17. Rayleigh Scattering http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html#c2

  18. Mie Theory for mr=1.5

  19. Normalized Phase Functions From Mie Theory

  20. Global Annual Energy Balance Kiehl and Trenberth (1997); IPCC (2001)

  21. Zonal Average Irradiance Solar Terrestrial Net Meridional Transport

  22. Cloud Radiative Forcing from ERBE

  23. Radiative Equilibrium & Role of Convection

  24. Solar Heating Rates from Model

  25. Zonal Annual Average from Satellite

  26. Results from SOCRATES (2-D Radiative-Chemical) http://acd.ucar.edu/models/SOCRATES/socrates/socrates1.html http://acd.ucar.edu/models/SOCRATES/socrates/socrates1.html

  27. Annual Mean Net Radiation Flux from Surface Based Measurements

  28. Terrestrial IR Spectra

  29. Modelled IR Fluxes

  30. Global mean radiative forcing of the climate system for the year 2000, relative to 1750 3 Halocarbons N O Aerosols 2 2 CH 4 Warming Black carbon from CO 1 Tropospheric 2 Aviation-induced Mineral fossil fuel Solar ozone dust burning Radiative forcing (W m-2) Contrails Cirrus 0 Stratospheric Organic ozone Land-use carbon Biomass (albedo) Cooling from Aerosol -1 burning Sulphate only fossil indirect fuel effect burning -2 High Medium Low Very Very Very Very Very Very Very Very Medium Low Low Low Low Low Low Low Low LevelofScientificUnderstanding

  31. Global Annual Energy Balance Kiehl and Trenberth (1997); IPCC (2001)

  32. Radiative Transfer Equation Radiance Cosine of solar zenith angle Azimuthal Angle Beer’s Law SourceFunction Optical Depth

  33. Plane Parallel Radiances

  34. Solution to the Radiative Transfer Equation Upward Radiance Downward Radiance

  35. SUN Single & Multiple Scattering Source Source Function Multiple Scattering Term Single Scattering Term

  36. Surface Reflectance

  37. Bi-directional Reflectance Distribution Function (BRDF)

  38. Surface Albedo

  39. Remote Sensing of Clouds

  40. Effect of Clouds from Radiative-Convective Model

  41. Solar Albedo of Clouds - Theory

  42. Indirect Aerosol Effect - ShiptracksL1B true color RGB composite (25 April 2001)

  43. Effective radius retrieval (using 2.1 µm band, all phases) 60 45 re (µm) 30 15 0

  44. Shiptracks from MODIS Indirect Aerosol Effect July 1, 2003

  45. Global Annual Energy Balance Kiehl and Trenberth (1997); IPCC (2001)

  46. IR Brightness Temperature from ER-2 (Clear)

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