Retrieval and characterization of ozone profiles from solar infrared spectra at the Jungfraujoch

Abstract

[1] Vertical distributions of ozone from June 1996 to November 2000 have been retrieved from high-resolution Fourier transform infrared (FTIR) solar absorption spectra recorded at the primary Network for Detection of Stratospheric Change station of the Jungfraujoch in the Swiss Alps (46.5°N, 8°E, 3580 m above sea level (asl). The retrievals were performed using the Optimal Estimation Method (OEM), both in a narrow spectral interval (1002.567-1003.2 cm À1 ) and in a broad spectral interval (1000.0-1005.0 cm À1 ) in the O 3 9.6-mm band. A thorough characterization of the retrievals has been performed following the lines of OEM, including an information content analysis, a study of the correlations between retrieved instrumental parameters and retrieved ozone concentrations, and an evaluation of the O 3 profile error budget. It is demonstrated that the information content is significantly higher for spectra in the broad microwindow, resulting in higher vertical resolutions, on the order of 8 km, of the retrieved profiles extending up to 40 km, and less correlations between retrieved parameters. An independent statistical verification of the retrieval results and their characterization has been performed by comparison of the FTIR ozone profiles with independent measurements. These are the ozone profile measurements from balloon soundings at Payerne, from the microwave radiometer at Bern and the lidar at Observatoire de HauteProvence (OHP), and the total column data from the Dobson spectrophotometer at Arosa. Applying the optimum retrieval procedure in the broad spectral interval, an excellent agreement has been found between the FTIR O 3 profile data and the correlative data. The largest offset of the FTIR data in comparison with the correlative data is found with respect to the lidar data in the 24-to 40-km layer, and is on the order of 5%. No systematic biases have been found in the troposphere, neither in the upper troposphere-lower stratosphere (UTLS) up to 18 km. The dispersion of the relative differences between the data sets, if any, is never larger than half of the natural ozone variability.

NO<sub>2</sub> seasonal evolution in the north subtropical free troposphere

“…Diagonal elements of S a are usually chosen to be a percentage of x a . In this case, following the L-curve method described in Schofield et al (2003), they have been set to 100 % of x a , and its nondiagonal elements are calculated as follows (Barret et al, 2002;Friess et al, 2006):…”

Validation of ozone measurements from the Atmospheric Chemistry Experiment (ACE)

“…All available measurements made by the satellite-and ground-based instruments, in the three year period from 2004 through to the end of 2006, were used to determine the Barret et al (2002Barret et al ( , 2003, for use within the European project UFTIR: "Time series of Upper Free Troposphere observations from a European ground-based FTIR network" (http://www.nilu.no/ uftir/). difference profiles.…”

Insights into Tikhonov regularization: application to trace gas column retrieval and the efficient calculation of total column averaging kernels

“…The atmospheric abundance of several trace gases are retrieved (e.g. O 3 (Schneider et al, 2008;Barret et al, 2002), HNO 3 (Vigouroux et al, 2007;Griesfeller et al, 2005), CO (Yurganov et al, 2005(Yurganov et al, , 2004Borsdorff and Sussmann, 2009;Rinsland et al, 2002;Pougatchev and Rinsland, 1995), CO 2 (Yang et al, 2002), and CH 4 (Angelbratt et al, 2011;Washenfelder et al, 2003)). For the SWIR and mid-IR range, these measurements are provided by the Network for the Detection of Atmospheric Composition Change (NDACC) Infrared Working Group (IRWG) and the Total Carbon Column Observing Network (TCCON).…”