Solar Energy Transfer
Assignment 3 - Transport of Solar Direct Beam
Due 21 February, 2000

Question 1

Points will be lost for incomplete homework format and incomplete labeling of figures.

Radiation objective:

To become familiar with calculating the direct beam radiative transfer and appreciate some applications.

MATLAB objective:

To use a computer program to perform sensitivity studies.

Part A

Solartrans.m computes the transmittance and direct beam solar spectral flux at the surface.  It does not include Rayleigh extinction. 

• Add Rayleigh extinction to solartrans.m (1 point)
• Clearly label changes made in the document (1 point)
• Include code and flowchart of code, including your modifications (1 point)

Part B

Modify code by changing solar zenith angle, ozone amounts and water vapor amounts. Calculate and plot the solar beam spectral flux at the surface for these conditions (2 points):

• Solar zenith angle = 30 degrees
• Ozone amount = 0.4 cm
• Water vapor amounts = 3 cm & 6 cm
• Assume a surface pressure of 1013 mb

Part C

How would you estimate the total amount of water vapor (in cm) in the atmosphere by measuring the direct solar beam flux at the surface?

• Select a wavelength at which to make the measurements (1 point)
• Support selection (there are a number of correct answers) using calculations and any other material you feel is relevant to the problem (4 points)
• Hint:  you know the top of the atmosphere spectral flux and once the instrument is built, you will also have the measured surface spectral flux at the surface. What you need is an appropriate wavelength that produces a good relationship between these two known parameters and U, the parameter you want.