The Effect of the Earths Atmosphere on Solar Radiation

(supervisor: Huw Morgan)

Nature of project: experimental, data analysis

Available to full-time physicists or joint students.

Project description and methodology

The student will measure the solar spectrum at Aberystwyth in the visible at several times during the day. From this data the effect of atmospheric thickness on the spectrum may be inferred. Measurements made over several days may allow the student to make conclusions on the effect of different atmospheric conditions on the measured solar spectrum. The student will compare the measured spectrum with measurements of the solar spectrum outside Earths atmosphere made by satellite. The student will: Build a simple measuring tool comprising spectrograph, laptop and fibre. Care: use neutral filters at the front end of the system to reduce the Sun's intensity!!! Take regular measurements with detailed notes.

A successful project will develop beyond the above in one/some of the following directions:
Take into account instrumental and other systematic errors (loss along fibre optics, dark currents in detector, flat response of detector etc.) Interpret the data sensibly, compare with solar spectrum measured from satellite above Earth's atmosphere. Compare to published works.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: A 4th year student will be expected to integrate the observing apparatus into a more sophisticated telescope system.

Initial literature for students:

  1. The spectral distribution of sunlight at the Earths surface, D.M. Gates, Science, 1966
  2. The SOLAR2000 empirical solar irradiance model and forecast tool, Tobiska et al, Journal of Atmospheric and Solar-Terrestial Physics
  3. This Wikipedia page is good for finding other references and online resources: http://en.wikipedia.org/wiki/Sunlight

Novelty, degree of difficulty and amount of assistance required

The spectrograph comes with a good software package. A motivated student will likely need only minimal guidance.

Project milestones and deliverables (including timescale)

milestoneto be completed by
build and test system against standard lampsend of November
integration into a more sophisticated observing system(4th year)end of November
take regular measurements noting weather at time of measurementsend of October
plot results and compare with standard solar reference spectrum - interpret any significant differences from solar reference spectrumEaster

Students taking this project will have to submit a full risk assessment form