Measurement of chlorine nitrate in the stratosphere using the nu(4) and nu(5) bands

We present laboratory measurements of the absorption cross sections of the vg band (540-580 cm(-1)) of chlorine nitrate made under stratospheric conditions of temperature and pressure. We use the measured cross sections and observed mid-infrared stratospheric emission spectra to retrieve mid-latitude vertical mixing ratio profiles for both day and night in the altitude range 20-34 km, and compare the results with a sunset profile obtained simultaneously from solar absorption measurements of the v(4) Q branch at 780 cm(-1). The profiles obtained using these two methods are shown to be in excellent agreement, validating retrievals using the v(4) band. We also find good agreement in this altitude range between the observed day/night ratio and the results of a 1-D photochemical model.