Simultaneous spectroscopic determination of the latitudinal, seasonal, and diurnal variability of stratospheric N₂O, NO, NO₂, and HNO₃

Abstract

The importance Of NOx compounds to stratospheric chemistry has been clearly established. We report below on a program to measure latitudinal, seasonal, and diurnal variations in stratospheric N2O, NO, NO2, and HNO3 amounts. Through the use of airborne Fourier transform absorption spectroscopy, we determine simultaneously column amounts above 12 km of the four molecules listed above. Nitrous oxide (N2O) is found to have a fairly uniform distribution with latitude and season, with a stratospheric column abundance of 8.1 × 1017 molecules cm−2. Nitric oxide (NO) amounts are shown to decrease with increasing latitude in winter. A 50% decrease in high latitude winter amounts is observed as compared with low latitude values near 3.0 × 1015 molecules cm−2. Nitrogen dioxide (NO2) stratospheric amounts increase in summer with increasing latitude. Equatorial values are near 3.0 × 1015 molecules cm−2 above 12 km. A factor of 3–4 increase in higher latitude summertime NO2, as compared to winter NO2, is observed. Nitric acid (HNO3) amounts show a general increase toward higher latitudes and a marked increase in mid‐latitude winter as compared to summer. Winter amounts may be highly variable with a value near 1.0 × 1016 molecules cm−2.

Remote Sounding of Vertical Profiles of Atmospheric Ozone and Nitrous Oxide with a Tunable Diode Laser Heterodyne Spectrometer

“…The difference between the two profiles on November 8, 1988 andJanuary 6, 1989 is very small. This result is consistent with the behavior of N2O concentration shown in the literature (Cicerone et al, 1978;Coffey et al, 1981;Hirota et al, 1988). A comparison was made with the balloon experiment at Sanriku (39*09'N, 141*49'E), about 130 km northeast from Sendai, on September 3, 1985(Nakazawa, private communication, 1988.…”

Validation of MIPAS-ENVISAT NO<sub>2</sub> operational data

“…Stratospheric NO 2 measurements have been carried out since the 1970s from a variety of airborne and ground-based platforms using in-situ and remote sensing techniques (e.g., Noxon et al, 1979;Coffey et al, 1981;Kondo et al, 1985;Roscoe et al, 1986;Pommereau and Goutail, 1988;Webster et al, 1990;Pfeilsticker and Platt, 1994;Chance et al, 1996;Renard et al, 1996;Wetzel et al, 1997;Sen et al, 1998;Payan et al, 1999).…”

Infrared Absorption Spectroscopy

“…In contrast to in situ measurements, where local mixing ratios are determined, remote FTIR measurements do not readily yield detailed mixing ratio distributions but rather total vertical column amounts in units of molecules cm −2 above the ground-based or airborne platform (Coffey et al, 1981). However, as we will see, this is a distinct advantage for temporal trend analysis.…”

“…As discussed in detail by Coffey et al (1981), vertical column amounts are determined from remote FTIR measurements from the integrated absorption along the line of sight to the sun, and then this quantity is converted to a vertical column amount based on the viewing geometry (see Chapter 3 for details). Since both depend upon the absorber distribution, a relative absorber distribution profile, based upon measurements and/or model mixing ratios, is assumed.…”

“…The total vertical column is then determined by summing up all the scaled vertical absorber layers. A more detailed discussion of these procedures can be found in Coffey et al (1981).…”