CARVE-FTS Observations of Arctic CO2, CH4, and CO - Overview of Retrieval Methodology

The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is an aircraft-based Earth System Science Pathfinder Venture Class mission that will collect detailed measurements of important greenhouse gases on local to regional scales in the Alaskan Arctic and demonstrate new remote sensing and improved modeling capabilities to quantify Arctic carbon fluxes and carbon cycle-climate processes. Aircraft observations will be made during Spring, Summer, and Fall of 2012-14. The CARVE instrument suite includes in situ observations of greenhouse gases, an L-Band radar to measure surface parameters, and a 3-channel near-IR Fourier Transform Spectrometer (FTS), with spectral ranges of 12,920-13,180, 5,820-6,380, and 4,200-4,322 cm-1, for column retrievals of CO2, CH4, and CO, together with O2 and H2O. Thus, the spectral region covered by CARVE overlaps (and extends) space-based observations currently made by SCIAMACHY and GOSAT, as well as the upcoming OCO-2, providing opportunities for synergistic studies and validation. We present an overview of FTS instrument capabilities, observation strategies, and the approach and methodology of FTS spectral retrievals of CO2, CH4, and CO dry-air columns. Expected FTS retrieval performance for each target gas are assessed based on synthetic spectra. Pre-mission test flights (to be conducted in October/November 2011) will provide preliminary test results of the FTS radiance sensitivity, spectral stability, and other instrument parameters.