Abstract. Time series of CO and C2H6 measurements have been derived from highresolution infrared solar spectra recorded in Lauder, New Zealand (45.0øS, 169.7øE, altitude 0.37 km), and at the U.S. National Solar Observatory (31.9øN, 111.6øW, altitude 2.09 km) on Kitt Peak. Lauder observations were obtained between July 1993 and November 1997, while the Kitt Peak measurements were recorded between May 1977 and December 1997. Both databases were analyzed with spectroscopic parameters that included significant improvements for C2H 6 relative to previous studies. Target CO and C2H 6 lines were selected to achieve similar vertical samplings based on averaging kernels. These calculations show that partial columns from layers extending from the surface to the mean tropopause and from the mean tropopause to 100 km are nearly independent. Retrievals based on a semiempirical application of the Rodgers optimal estimation technique are reported for the lower layer, which has a broad maximum in sensitivity in the upper troposphere. The Lauder CO and C2H 6 partial columns exhibit highly asymmetrical seasonal cycles with minima in austral autumn and sharp peaks in austral spring. The spring maxima are the result of tropical Nadir-viewing infrared measurements of CO were obtained from the U.S. space shuttle in

The vertical distribution of the ozone in the troposphere and the lower and middle stratosphere has been retrieved from a series 0.005–0.013 cm−1 resolution infrared solar spectra recorded with the McMath Fourier transform spectrometer at the National Solar Observatory on Kitt Peak. The analysis is based on a multilayer line‐by‐line forward model and a semiempirical version of the optimal estimation inversion method by Rodgers. The 1002.6–1003.2 cm−1 spectral interval has been selected for the analysis on the basis of synthetic spectrum calculations. The characterization and error analysis of the method have been performed. It was shown that for the Kitt Peak spectral resolution and typical signal‐to‐noise ratio (≥100) the retrieval is stable, with the vertical resolution of ≈5 km attainable near the surface degrading to ≈10 km in the stratosphere. Spectra recorded from 1980 through 1993 have been analyzed. The retrieved total ozone and vertical profiles have been compared with total ozone mapping spectrometer (TOMS) satellite total columns for the location and dates of the Kitt Peak measurements and about 100 ozone ozonesoundings and Brewer total column measurements from Palestine, Texas, from 1979 to 1985. The total ozone measurements agree to ±2%. The retrieved profiles reproduce the seasonally averaged variations with altitude, including the ozone spring maximum and fall minimum measured by Palestine sondes, but up to 15% differences in the absolute values are obtained.

(1 ppbv = 10 -9 per unit volume), more than a factor of 3 above the background level.The HCN enhancements continued through the end of the observational series. Backtrajectory calculations suggest that the emissions originated at low northern latitudes in southeast Asia. Surface CO mixing ratios and the C2H 6 tropospheric columns measured during the same time also showed anomalous autumn 1997 maxima. The intense and widespread tropical wild fires that burned during the strong E1 Nifio warm phase of 1997-1998 are the likely source of the elevated emission products. IntroductionThe purpose of this paper is to report and interpret a time series of measurements derived from high-resolution (

Abstract. The METOP-A satellite Infrared AtmosphericSounding Interferometer (IASI) Level 2 products comprise retrievals of vertical profiles of temperature and water vapor. The error covariance matrices and biases of the most recent version (4.3.1) of the L2 data were assessed, and the assessment was validated using radiosonde data for reference. The radiosonde data set includes dedicated and synoptic time launches at the Lindenberg station in Germany. For optimal validation, the linear statistical Validation Assessment Model (VAM) was used. The VAM uses radiosonde profiles as input and provides optimal estimate of the nominal IASI retrieval by utilizing IASI averaging kernels and statistical characteristics of the ensembles of the reference radiosondes. For temperatures above 900 mb and water retrievals above 700 mb, level expected and assessed errors are in good agreement. Below those levels, noticeable excess in assessed error is observed, possibly due to inaccurate surface parameters and undetected clouds/haze.

Abstract. The latitudinal variations of atmospheric trace gas column abundances have been measured during a ship cruise between 57øN and 45øS on the central Atlantic. The measurements were performed in October 1996 using high-resolution solar absorption spectroscopy in the infrared. The analysis method employed permits the retrieval of the total column densities of 20 different trace gases and for a few compounds the vertical mixing ratio profiles. For CH 4 an interhemispheric difference of 3% was observed. The total columns of the shorter-lived trace gases CO and C2H 6, analyzed between 57øN and 45øS, reveal a slight maximum in the tropics and a substantial increase north of 45øN. The total columns of C2H 2 and HCN, detectable between 30øN and 30øS, reveal a maximum in the tropics of the Southern Hemisphere. For CH20, studied between 57øN and 45øS, a well-pronounced maximum is observed in the tropics.The profile retrieval gives high mixing ratios for CO, C2H 6, and 0 3 north of 40øN in the lower troposphere. In the tropics high concentrations are found for all three compounds in the entire troposphere, even above 12 km. The measurements have been used to estimate averaged mixing ratios of the trace gases for the free troposphere between 0 and 12 km. In the tropics the data give high values: for example, more than 200 pptv for HCN, 750 pptv for CH20, 100 ppbv for CO and 100 pptv for C2H 2. These values are comparable to or higher than what has been observed at midlatitudes, indicating the importance of biomass burning emissions on the tropospheric composition.