Abstract

Abstract. We present atmospheric ozone (O3) profiles measured over central Mexico between November 2012 and February 2014 from two different ground-based FTIR (Fourier transform infrared) solar absorption experiments. The first instrument offers very high-resolution spectra and contributes to NDACC (Network for the Detection of Atmospheric Composition Change). It is located at a mountain observatory about 1700 m above the Mexico City basin. The second instrument has a medium spectral resolution and is located inside Mexico City at a horizontal distance of about 60 km from the mountain observatory. It is documented that the retrieval with the high- and medium-resolution experiments provides O3 variations for four and three independent atmospheric altitude ranges, respectively, and the theoretically estimated errors of these profile data are mostly within 10 %. The good quality of the data is empirically demonstrated above the tropopause by intercomparing the two FTIR O3 data, and for the boundary layer by comparing the Mexico City FTIR O3 data with in situ O3 surface data. Furthermore, we develop a combined boundary layer O3 remote sensing product that uses the retrieval results of both FTIR experiments, and we use theoretical and empirical evaluations to document the improvements that can be achieved by such a combination.

Highlights

  • O3 is an important atmospheric trace gas

  • To our knowledge we present the first ground-based FTIR remote sensing data of O3 profiles for Latin America

  • We work with two different FTIR experiments, one of which is located in the megacity of Mexico City and another about 1700 m above the city at a distance of 60 km

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Summary

Introduction

O3 is an important atmospheric trace gas. In the stratosphere O3 absorbs ultraviolet (UV) radiation, thereby protecting all living organisms. A comprehensive investigation of these complex climatechemistry interactions and the particular role of O3 is only possible by combining atmospheric models with observations (Dameris and Jöckel, 2013; Hassler et al, 2013) In this context ground-based high-resolution solar absorption FTIR spectrometer measurements have been proven to be useful, providing information on the vertical distribution of O3 and other trace gases We would like to point out that ground-based remote sensing measurements of the vertical O3 distribution between the boundary layer and the upper stratosphere are challenged by the fact that the O3 concentrations strongly vary with altitude This is shown, which shows a typical tropical O3 profile (blue line for volume mixing ratios and black for abundances relative to total abundances).

Ground-based FTIR remote sensing
Experimental set-up
Retrieval method
Error analyses
Observations at Altzomoni
Observations at UNAM
A Arbitrary radiances
Logarithmic-scale representation
Free tropospheric and stratospheric O3
Seasonal cycle above Altzomoni
Intercomparison between UNAM and Altzomoni data
In situ monitoring of air pollution in Mexico City
Intercomparison of remote sensing data with in situ data
Analytical description of the combined product
The working principle of the combined product
Discussion
Summary and outlook
Bruker Vertex 80 at UNAM
Atmospheric covariances
Findings
Non-measurable covariances
Comparability between different remote sensing data
Full Text
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