Virolainen, Y.A., Timofeyev, Y.M., Poberovsky, A.V., Polyakov, A.V. Information Content of the Ground-Based FTIR Method for Atmospheric HNO3 Vertical Structure Retrieval. Atmos Ocean Opt 36, 24–29 (2023). https://doi.org/10.1134/S102485602302015X
Abstract
Nitric acid plays an important role in atmospheric chemistry; for this reason, it is currently monitored by various methods and instruments.
The ground-based FTIR method based on spectral measurements of solar radiation by Bruker Optics IFS 125HR spectrometers allows one to retrieve not only the total column HNO3 but also its content in individual atmospheric layers.
Analysis of HNO3 content series at the St. Petersburg NDACC site between 2009 and 2021 shows that the spectroscopic measurements under consideration contain about three independent parameters on the average, which makes it possible to obtain information about the HNO3 content in several layers of the atmosphere.
The mean random errors of HNO3 measurements amount to 3.9, 14, and 1.6% for the total atmospheric, tropospheric (up to 15 km), and stratospheric (above 15 km) content, respectively. Thus, the FTIR method considered is more sensitive to changes in the stratospheric HNO3 content. The absorption of solar radiation by nitric acid in the measured spectra overlaps with the absorption by water vapor; therefore, the information content and accuracy of HNO3 measurements are maximal in winter and minimal in summer: in winter, measurements are carried out mainly at low sun and low humidity; in summer, vice versa.