Total column CO<sub>2</sub> measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles

Abstract

Abstract. An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO 2 and O 2 and other gases. Measured CO 2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in JanuaryFebruary 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clearsky low airmass relative precision of 0.1% is demonstrated in the CO 2 and O 2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS X CO 2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.

A method for colocating satellite <i>X</i><sub>CO<sub>2</sub></sub> data to ground-based data and its application to ACOS-GOSAT and TCCON

“…In certain applications it may be more reasonable to assume that a satellite observation is an average of the true geophysical process Y (·) over the area of the footprint plus a measurement-error term. The resulting process of inferring a spatial process at one resolution from data at another resolution, also known as the change-of-support problem, is more complex; see Gotway and Young (2002) for a review. In general, there is no analytical solution for estimating the parameters of standard variogram models from areal data (e.g., spherical, exponential, etc.…”

“…TCCON X CO 2 data in turn are validated against integrated aircraft profiles Deutscher et al, 2010; and have a precision and accuracy of ∼ 0.8 ppm .…”

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].…”

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

“…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].…”