| The development of instrumentation for in situ measurements of NO;A feasibility study of the application of single-photon laser-induced fluorescence (LIF) to detection of NO;The accuracy and long-term precision of in situ measurements of ClO are critical to resolving several outstanding issues in stratospheric ozone chemistry: (a) the importance of chlorine catalysis relative to other ozone loss processes, (b) the steady decline of midlatitude ozone during the past fifteen years, and (c) the current controversy surrounding chlorine partitioning in the lower stratosphere. A laboratory study was undertaken to develop a comprehensive and quantitative understanding of the operation and calibration of the ClO instrument from first principles. Four sources of systematic error were identified: (a) spectral hole burning occurring inside the chlorine atomic resonance lamp (likely the largest source of systematic error), (b) spectral impurities in the Cl lamp emission spectrum, (c) increases in chamber scatter during field deployment, and (d) underestimate of the optical pathlength assumed for laboratory calibrations based on resonance absorption. The first three effects cause (ClO) to be underestimated while the fourth and likely smallest (;Where possible the magnitude and variability of these sources of systematic error were quantified. In each case practical approaches to the diagnosis and elimination of these measurement artifacts were developed. |
