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By Madhu Gyawali Narayan Adhikari Yadab Paudel

FTIR Measurements on November 06,08 at Reno. By Madhu Gyawali Narayan Adhikari Yadab Paudel. PHYS 749. Nov 18, 08. UNIVERSITY OF NEVADA , RENO,NV. Introduction, Instrumentation:.

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By Madhu Gyawali Narayan Adhikari Yadab Paudel

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  1. FTIR Measurements on November 06,08 at Reno By Madhu Gyawali Narayan Adhikari Yadab Paudel PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  2. Introduction, Instrumentation: FTIR is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, 5 microns to 20 microns. FTIR collects infrared spectra by an interferogram of a sample signal using an interferometer, then performs a Fourier Transform on the interferogram to obtain the spectrum. An interferometer is an instrument that uses the technique of superimposing (interfering) two or more waves, to detect differences between them. The FTIR spectrometer uses a Michelson interferometer. (Source-Pat Arnott,ATMS 749) http://en.wikipedia.org/wiki/Fourier_transform PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  3. Introduction… IR Window 8-13 microns. IR radiation from the Earth’s surface escapes to space (cooling the Earth). Absorption by O3 near 9 microns ‘dirties’ the window. Figures: From Lecturer’s Note (Pat Arnott) PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  4. Results: Temperature Vs. Wave number • Cloudy sky: window region high temperature (≈ 275 K, 7:28AM) • Clear sky: Lower temperature from deep surface (≈ 180K, 12:00AM) • Surface temperature ≈ 278-285K PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  5. Results: Temperature Vs. Wave number • Co2 peaks around wave number 670 cm-1 PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  6. Results: Temperature Vs. Wave number PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  7. Results: Radiance Vs. wave number PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

  8. Results: Irradiance Vs. wave number (model) PHYS 749 Nov 18, 08 UNIVERSITY OF NEVADA , RENO,NV

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