Constraints on Global Carbon Fluxes
My PhD research focused on understanding the carbon cycle, using observations of total column CO₂ made using high resolution Fourier transform spectrometry by the TCCON network. The total column is the integrated mass of CO₂ in the atmosphere above a given location. As such, it contains different information than traditional measurements of CO₂ mixing ratio made in situ. Understanding what information is contained in total column CO₂ observations will be helpful in interpreting satellite data from GOSAT and OCO-2.

We use our observations from ground-based observatories in conjunction with an atmospheric transport model to probe the sources of variations in the column. We find that column CO₂ has a very large footprint and that variations primarily reflect large-scale flux distributions. Such data provide a strong constraint on large scale fluxes and will be useful in flux inversion models to estimate surface carbon exchange. We use these data to probe many aspects of the carbon cycle, including the distribution of terrestrial carbon exchange, geographic patterns in total column fossil CO₂, and emission ratios of CO₂, CO, and CH₄ from biomass burning.

Atmospheric Retrievals using Fourier Transform Spectrometry
I developed an algorithm to retrieve aerosol optical properties from high resolution Fourier transform spectrometrn (FTS) spectra, as well as an algorithm to eliminate solar brightness fluctuations from data obtained by FTS. Variable cloud or aerosol optical depth can degrade spectra and subseqent gas retrievals. By recording a DC signal, we can correct for the brightness fluctuations and improve the precision of our retrievals.

Climate Stability
I developed a one-dimensional energy balance model based on eddy heat flux scaling laws determined from a general circulation model (GCM). Such a model could be coupled to ocean or ice models to probe climate stability over a range of climates.