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We present the first near‐global set of correlated measurements of stratospheric HCl and ClONO2concentrations. These data, obtained from the Upper Atmosphere Research Satellite (UARS) between August 1992 and March 1993, are analyzed using the Goddard trajectory mapping technique. These data indicate that, between 20 and 30 km altitude and 60°N to 60°S latitude, total inorganic chlorine (Cly) is fairly evenly distributed between ClONO2and HCl, with HCl the slightly more dominant reservoir. The sum of UARS measurements of HCl and nighttime ClONO2, which approximates Clyat these altitudes, closely agrees with Clyderived from a tracer‐Clyrelation originally derived from aircraft data, increasing confidence in the UARS data. Comparisons between these data and two‐dimensional model results suggest that models underpredict ClONO2(overpredict HCl) near 20 km and overpredict ClONO2(underpredict HCl) near 30 km, although the 20‐km underprediction is not as large as analyses of aircraft measurements have indicated.

A plane-parallel approximation using fascode to calculate upward and downward IR flux density and angle-averaged radiance is described and tested against results that account for planetary curvature. The method is further developed to calculate the excitation of NO(v = 1) due to absorption of upwelling radiation in the earth’s atmosphere. The algorithm is applied to a standard set of atmospheric models, in addition to typical and extreme desert atmospheric models which are included to maximize the effect. The results of this work show that upwelling radiation typically contributes <2.5% to the total NO(v = 1) excitation in the midstratosphere rises to ~5% at 50 km and becomes increasingly significant at higher altitudes. It is shown that in the mesosphere excitation due to upwelling and solar radiation become important compared to the dominant processes, thermal collisions, and chemical excitation. An approximate technique utilizing meteorological data, namely, tropospheric temperature, pressure, and humidity profiles, is developed to estimate the excitation of NO(v = 1) in the middle atmosphere. This technique would facilitate the retrieval of the NO mixing ratio from earthlimb emission data, as might be obtained from a satellite-borne limb sounding experiment, since it could be used to approximate the contribution of upwelling radiation to the NO(v = 1) non-LTE vibrational temperature efficiently.