Knowledge Bank

SAGE III (an EOS remote sensing experiment scheduled to orbit the Earth) will utilize the prominent features of the oxygen A-band to monitor atmospheric pressure and temperature. To support this, a laboratory study has been undertaken to measure intensities, pressure-broadened line widths and pressure-induced frequency shifts for the strongest transitions between 13040 and $13165cm-1$. Experimental values have been obtained from over thirty spectra recorded at $0.02cm-1$ resolution with the McMath Fourier transform spectrometer located at Kitt Peak National Observatory / National Solar Observatory in Arizona. These data have been taken with gas samples of pure oxygen and oxygen / nitrogen mixtures at room and cold temperatures (down to 200 K) in order that the temperature dependences of the self-and nitrogen-broadened widths can be determined. Finally, for calibration, a broad band spectrum has been recorded between 4000 and $14000cm-1$ using InSb and Silicon diode detectors simultaneously; with this, the line positions of the A-band of oxygen have been referenced to CO $standardsa$ in the 2-0 and 3-0 bands (at 2.35 and $1.57\mu$m $respectively).b$