Carbon dioxide column abundances at the Wisconsin Tall Tower site

Abstract

We have developed an automated observatory for measuring atmospheric column abundances of CO2 and O2 using near‐infrared spectra of the Sun obtained with a high spectral resolution Fourier Transform Spectrometer (FTS). This is the first dedicated laboratory in a new network of ground‐based observatories named the Total Carbon Column Observing Network. This network will be used for carbon cycle studies and validation of spaceborne column measurements of greenhouse gases. The observatory was assembled in Pasadena, California, and then permanently deployed to northern Wisconsin during May 2004. It is located in the heavily forested Chequamegon National Forest at the WLEF Tall Tower site, 12 km east of Park Falls, Wisconsin. Under clear sky conditions, ∼0.1% measurement precision is demonstrated for the retrieved column CO2 abundances. During the Intercontinental Chemical Transport Experiment–North America and CO2 Boundary Layer Regional Airborne Experiment campaigns in summer 2004, the DC‐8 and King Air aircraft recorded eight in situ CO2 profiles over the WLEF site. Comparison of the integrated aircraft profiles and CO2 column abundances shows a small bias (∼2%) but an excellent correlation.

The Total Carbon Column Observing Network

“…Details of the instrumentation can be found in appendix A(a), and specific information about Park Falls and Darwin can be found in Washenfelder et al [17] and Deutscher et al [18].…”

Comparison of carbon dioxide volume mixing ratios measured by GOSAT TANSO-FTS and TCCON over two sites in East Asia

“…We obtained the TCCON data from https://tccon-wiki.caltech.edu/Network Policy/ Data Protocol. Those ground based FTS has high spectral resolution (0.02 cm -1 ) and high signal-to-noise ratio (SNR) (Washenfelder et al, 2006). There are located over 20 TCCON site around the world (Yang et al, 2002).…”

Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space. Part 2: Algorithm intercomparison in the GOSAT data processing for CO2 retrievals over TCCON sites

“…[10] The basic specifications of the GOSAT instrument [Hamazaki et al, 2005;Kuze et al, 2009;Nakajima et al, 2010] and TCCON measurements [Washenfelder et al, 2006;Wunch et al, 2011a], as well as the atmospheric transport model (NIES-08.1i) [Belikov et al, 2012] were outlined in Part 1. In this section, we specify observation conditions and GOSAT-TCCON coincidence criteria used in this study.…”

“…According to several theoretical studies, the user requirements for the GOSAT retrieval quality are rather stringent [Rayner and O'Brien, 2001;Houweling et al, 2004;Miller et al, 2007;Chevallier et al, 2007]; for example, regional biases of a few tenths of a part per million could hamper surface flux inversions [Miller et al, 2007;Chevallier et al, 2007]. An important aspect for validating the GOSAT retrievals and meeting the user requirements is the use of the ground-based high-resolution Fourier transform spectrometer (FTS) measurements from the Total Carbon Column Observing Network (TCCON) [Washenfelder et al, 2006;Wunch et al, 2011a], whose uncertainties in X CO2 are expected to be within 0.8 ppm (2s) [Wunch et al, 2010;Deutscher et al, 2010;Messerschmidt et al, 2010]. Several studies have compared GOSAT retrieval gas products from different algorithms against TCCON measurements Butz et al, 2011;Wunch et al, 2011bOshchepkov et al, 2012;Cogan et al, 2012].…”