We present vertical mixing ratio profiles for nitric acid (HNO3) recorded during the Middle Atmosphere Nitrogen TRend Assessment (MANTRA) 1998 balloon flight over Saskatchewan, Canada. The profiles are based on radiance spectra containing HNO3 thermal‐emission features and were collected during balloon ascent and over a latitude and longitude interval (52°± 0.2°N, 106.6° ± 0.5°W) between 3:30 and 6:30 am local time (9:30 and 12:30 UTC), 24 August 1998. The spectra were simultaneously recorded by two radiometer instruments in the 715–1250 cm−1 atmospheric window at an approximate instrument resolution of 20 cm−1. Profiles of CFC‐11, CFC‐12, ozone (O3), methane (CH4) and nitrous oxide (N2O) based on emission features in the same observation window are also presented. Raw radiance measurements are analysed using a forward estimation technique to recover multiple gas profiles from very low‐spectral resolution measurements of atmospheric radiance. The technique uses detailed atmosphere and instrument models and a least‐mean‐squares estimator to iterate maximum‐likelihood volume mixing ratio (VMR) from 7 to 30 km on a 2‐km grid. The analysis approach described is adaptable to other retrievals of multiple constituents from low‐resolution spectra recorded by lower‐cost, robust instrumentation developed for balloon and space flight. Averaging kernels and an error analysis are included in order to illustrate instrument sensitivity to vertical composition and expected accuracy. Results from each instrument compare favourably and show close agreement with HNO3 climatology results based on satellite observations made by the Microwave Limb Sounding (MLS) instrument, 1992–94.
No takes yet. Share an insight, caveat, or question.
Quine et al. (2005) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: