Balloon-borne radiometer measurements of Northern Hemisphere mid-latitude stratospheric HNO<sub>3</sub> profiles spanning 12 years

Abstract

Abstract. Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990-2002 are used to retrieve vertical profiles of HNO 3 , CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and optimization steps. The retrieved HNO 3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. We therefore find no evidence of long-term changes in the HNO 3 summer mid-latitude profile, although the uncertainty of our measurements precludes a conclusive trend analysis.

Network for the Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) trace gas measurements at the University of Toronto Atmospheric Observatory from 2002 to 2020

“…The variability in the HNO 3 measurements increases in winter as seen in Fig. 27c, in agreement with model predictions for a midlatitude site presented in Toohey et al (2007).…”

NDACC FTIR trace gas measurements at the University of Toronto Atmospheric Observatory from 2002 to 2020

“…The variability in the HNO3 measurements increases in winter as seen in Figure 27(c), in agreement with model predictions for a mid-latitude site presented in Toohey et al (2007).…”