ATMS 431A - Autumn 2006
Atmospheric Physics: Radiation and Boundary Layer
5 credits
M-T-W-TH-F 11:30-12:20 pm
Room ATG 610
Instructors:
Robert Wood, ATG 713, tel. 543-1203, robwood@atmos.washington.edu
Stephen Warren, ATG 524, tel. 543-7230, sgw@atmos.washington.edu
Grading:
30% Homework (8 assignments)
10% Quiz 1 (Friday 13 October)
25% Midterm Exam (Tuesday 31 October)
10% Quiz 2 (Friday 17 November)
25% Final Exam (Wednesday 13 December, 2:30-4:20pm)
Office Hours: MWF 12:20 – 1:00 (after class)
A. Boundary-Layer Meteorology: September 27 - October 31
(Lecturer: Wood)
Class website: http://www.atmos.washington.edu/~robwood/teaching/431/robwood_431.html
Text: S. Pal Arya, Introduction to Micrometeorology
Introduction:
What is micrometeorology and why is it important? What is the planetary boundary layer (PBL) and why does it exist? Different types of boundary layers.
Energy budget near the surface:
Concept of a surface energy budget; energy budget of a layer; impacts of surface fluxes; radiative balance; energy budgets of canopies, different surface types.
Soil temperature and heat transfer:
Surface and subsurface temperature and their interaction; thermal properties of soil and how this impacts heat transfer in soils; ground heat flux and its parameterization.
Air temperature and humidity in the PBL:
Why do the air temperature and humidity have the values they do? Thermodynamic relations and the energy equation; differences between unsaturated and saturated air; How does static stability impact boundary layer properties? local and nonlocal concepts of static stability; mixed layers and inversions; vertical profiles of temperature and humidity; what happens over the course of a day?.
Wind distribution in the PBL:
What happens to the wind near the surface? What controls the strength and direction of the wind in the PBL? Geostrophic and thermal winds; frictional effects and the surface roughness; effects of stability and mixing. What do observations tell us? How does the wind vary over the course of a day?
Viscous flows:
What is viscosity? Laminar and turbulent flows. Concepts of the Ekman layer. Laminar boundary layers.
Atmospheric turbulence, turbulent kinetic energy (TKE), and PBL momentum
equations:
Flow instability and transition to turbulence; the maintenance of turbulence; general characteristics; concept of high and low frequency variables (Reynolds averaging); turbulent fluxes and turbulent kinetic energy; eddies and their scales; important hypotheses about turbulence. How do we represent turbulent effects mathematically? TKE budget equation; concept of viscous eddies; gradient transport; basics of similarity theory.
B. Radiation Transfer: November 1 - December 8
(Lecturer: Warren)
Text: G.W. Petty, A First Course in Atmospheric Radiation (second edition, 2006)
Introduction and basic terminology and concepts:
The importance and relevance of the subject in the atmospheric sciences; the role of radiative transfer in the global energy balance; electromagnetic spectrum; radiance and irradiance; scattering, absorption, and emission.
Thermal emission:
Blackbody radiation; Kirchhoff's law; Beer-Lambert law; infrared radiative transfer equation (Schwarzschild's equation); plane-parallel atmospheres; remote sensing applications.
Absorption process in the atmosphere:
Absorption spectra of atmospheric gases; band models; solar heating rates; infrared cooling rates; photochemical processes and ozone layer; greenhouse effect, carbon dioxide and climate.
Solar radiation:
The sun as an energy source; the Earth's orbit about the sun (seasonal effects and orbital effects); solar spectrum and solar constant; solar insolation. Light scattering and solar radiative transfer in the atmosphere.
Earth radiation budget at the top of the atmosphere and at the surface;
Cloud radiative forcing