A ground-based high-resolution Fourier transform spectrometer (FTS)station has been established in Hefei, China to remotely measure CO, COand other greenhouse gases based on near-infrared solar absorption spectra.Total column measurements of atmospheric CO and CO weresuccessfully obtained from July 2014 to April 2016. The spectra collectedwith an InSb detector in the first year were compared with those collected byan InGaAs detector from July 2015, demonstrating that InGaAs spectra havebetter signal-to-noise ratios and rms of spectral fitting residuals relativeto InSb spectra. Consequently, the measurement precision of the retrievedXCO and XCO for InGaAs spectra is superior to InSb spectra, with about0.04 and 0.09 % for XCO, and 1.07 and 2.00 % for XCO withinclear-sky days respectively. Daily and monthly averages of column-averaged dryair mole fraction of CO show a clear seasonal cycle, while the dailyand monthly averages of XCO displayed no seasonal variation. Also, we analysedthe relationship of the anomalies of XCO and XCO, found that thecorrelations are only observable for individual days, and the data underdifferent prevailing wind conditions during the observations displayed weakcorrelation. The observations based on the high-resolution FTS were alsocompared with the temporally coinciding measurements taken with alow-resolution solar FTS instrument, the EM27/SUN. Ratioing the dailyaveraged XCO of EM27 and FTS gives an overall calibration factor of0.996 ± 0.001. We also compared ground-based observations from theTsukuba TCCON station with our observations, the results showing that thevariation in phase and seasonal amplitude of XCO are similar to ourresults, but the variation of XCO in Tsukuba is quite different from our datain Hefei. To further evaluate our retrieved data, we made use of satellitemeasurements. The direct comparison of our observations with the GreenhouseGases Observing Satellite (GOSAT) data shows good agreement of daily medianXCO, with a bias of −0.52 ppm and standard deviation of 1.63 ppm. The correlation coefficient () is 0.79 for daily medianXCO between our FTS and GOSAT observations. Daily median OrbitingCarbon Observatory 2 (OCO-2) data produce a positive bias of 0.81 ppm andstandard deviation of 1.73 ppm relative to our ground-based data. Our daily median XCO also show strong correlation withOCO-2 data, with correlation coefficient () of 0.83. Although therewere a limited number of data during the observations due to instrumentdowntime and adverse weather, the results confirm the suitability of theobservatory for ground-based long-term measurements of greenhouse gases withhigh precision and accuracy, and fulfil the requirements of the Total CarbonColumn Observing Network (TCCON).
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