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- Title
Background CO<sub>2</sub> levels and error analysis from ground-based solar absorption IR measurements in central Mexico.
- Authors
Baylon, Jorge L.; Stremme, Wolfgang; Grutter, Michel; Hase, Frank; Blumenstock, Thomas
- Abstract
In this investigation we analyze two common optical configurations to retrieve CO2 total column amounts from solar absorption infrared spectra. The noise errors using either a KBr or a CaF2 beam splitter, a main component of a Fourier transform infrared spectrometer (FTIR), are quantified in order to assess the relative precisions of the measurements. The configuration using a CaF2 beam splitter, as deployed by the instruments which contribute to the Total Carbon Column Observing Network (TCCON), shows a slightly better precision. However, we show that the precisions in XCO2 (D0.2095 . (Total Column CO2/Total Column O2) retrieved from >96% of the spectra measured with a KBr beam splitter fall well below 0.2%. A bias in XCO2 (KBr-CaF2) of C0.56±0.25 ppm was found when using an independent data set as reference. This value, which corresponds to C0.14±0.064%, is slightly larger than the mean precisions obtained. A 3-year XCO2 time series from FTIR measurements at the highaltitude site of Altzomoni in central Mexico presents clear annual and diurnal cycles, and a trend of C2.2 ppm yr-1 could be determined.
- Subjects
INFRARED spectra; ABSORPTION; INFRARED spectroscopy equipment; IR spectrometers; BEAM splitters
- Publication
Atmospheric Measurement Techniques, 2017, Vol 10, Issue 7, p2425
- ISSN
1867-1381
- Publication type
Article
- DOI
10.5194/amt-10-2425-2017