Instructor: Professor Stephen Warren
524
Atmospheric Sciences Bldg., 543-7230
sgw@atmos.washington.edu
Meeting Times: 10:30 - 11:50AM, T TH, ATG 610.
1. Introduction.
Composition and thermal structure of Earth's atmosphere
Vertical and seasonal distribution of greenhouse gases
Solar and terrestrial radiation spectra
2. Infrared radiation
Radiation nomenclature and units: radiance, irradiance, absorption
coefficients, emissivity, optical depth, Beer's law (handouts)
Radiative transfer equation including scattering
Blackbody radiation laws: Planck, Kirchhoff, Stefan-Boltzmann, Wien,
Rayleigh-Jeans
Local thermodynamic equilibrium (LTE); non-LTE.
Einstein relations,
statistical equilibrium equation (handouts; Houghton 5.6)
Solution of
longwave radiative transfer equation
Radiative equilibrium temperature distribution (Houghton ch.2)
Describe MODTRAN project
3. Absorption and emission of radiation by gases
Kinetic theory of gases (Sears and Salinger ch.9,11,12; Fleagle and Businger
ch.2)
Molecular energy levels; electronic, vibrational, rotational transitions.
Spacing of lines. (Barrow, handouts)
Spectra of carbon dioxide,
ozone, and water vapor. Water-vapor continuum.
Line shapes: natural, Doppler, pressure (collision) broadening.
(Houghton ch.4, Goody 3.6, Houghton and Smith 2.7, handouts)
Absorption by non-overlapping Lorentz lines: equivalent width
4. Absorption by bands of spectral lines. (Paltridge and Platt ch.7, Liou ch.4, Rodgers 1976)
Frequency-averaging of transmission. Band models (regular, random, Malkmus);
exponential-sum-fitting of transmission functions;
correlated-k-distributions; Lowtran, emissivity approximation.
Pressure-averaging of transmission. Scaling approximation, Curtis-Godson,
Chou-Arking
Angular-averaging of transmission. Exponential integrals,
diffusivity factor
5. Computation of heating rates by radiative-transfer equation
Radiation charts (Liou, Elsasser) Rodgers-Walshaw
Cooling-to-space approximation (Houghton 4.8, handouts)
Non-LTE radiative transfer in the upper atmosphere; Curtis matrix
(Houghton 5.6)
Homework: approximately 8 problem sets. 50% of grade.
Term project, 50% of grade.
The term project is to use an existing longwave radiative-transfer model to compute infrared radiation fluxes and cooling rates in the atmosphere. The model will be used to examine the effects of changing temperature and humidity profiles, and the vertical distribution of greenhouse gases (CO2, O3, CH4, . . . ) and the effect of clouds at various heights.
Houghton, J.T., 1986: The Physics of Atmospheres. Cambridge Univ. Press.
Thomas, G.E., and K. Stamnes, 1999: Radiative Transfer in the Atmosphere and Ocean. Cambridge Univ. Press.
Barrow, G.M., 1962: Introduction to Molecular Spectroscopy. McGraw-Hill.
Fleagle, R.G., and J.A. Businger, 1980: An Introduction to Atmospheric Physics. Academic Press.
Goody, R.M., and J.C.G. Walker, 1972: Atmospheres. Prentice-Hall.
Goody, R.M., and Y. Yung, 1989: Atmospheric Radiation. Oxford Univ. Press.
Houghton, J.T., and S.D. Smith, 1966: Infrared Physics. Oxford Univ. Press.
Liou, K.N., 1980: An Introduction to Atmospheric Radiation. Academic Press.
Menzel, D.H. (Ed.), 1966: Selected Papers on the Transfer of Radiation. Dover.
Paltridge, G.W., and C.M.R. Platt, 1976: Radiation Processes in Meteorology and Climatology. Elsevier.
Rodgers, C.D., and C.D. Walshaw, 1966: The computation of infra-red cooling rate in planetary atmospheres. Quart. J. Royal Met. Soc., 92, 67-92.
Rodgers, C.D., and C.D. Walshaw, 1976: Approximate Methods of Calculating Transmission by Bands of Spectral Lines. NCAR Technical Note TN-116+IA.
Sears, F.W., and G.L. Salinger, 1975: Thermodynamics, Kinetic Theory, and Statistical Thermodynamics.. Addison-Wesley.