## 1 Introduction
The concentration of CO\({}_{2}\) in the ABL is a function of the composition of the original air masses during ABL formation, exchanges with the land surface, and exchanges with the FT as described above, all modulated by variables like land-cover type and soil moisture. Given the role of the inversion as a filter of information between the ABL and the FT, it is important to note the physical processes that affect transport of CO\({}_{2}\) within the ABL. For example, horizontal transport within the ABL is estimated to move over the land surface at approximately 500 km day\({}^{-1}\) and the surface area influencing the concentration of a trace gas in the ABL, such as CO\({}_{2}\), ranges from 10\({}^{3}\) to 10\({}^{5}\) km\({}^{2}\)[18]. In addition, [PERSON] _et al_. [6] estimate that vertical transport from convective storm processes around the globe completely replaces the air masses in the ABL approximately 90 times per year, or every four days. Biological processes affecting CO\({}_{2}\) concentrations in the ABL include photosynthesis and respiration. Greater surface CO\({}_{2}\) concentration implies lower levels of photosynthesis and/or higher levels of respiration by plants and microbial communities. Decreased photosynthesis and increased respiration correspond with the end of the growing season and plant senescence or greater microbial activity associated with higher soil moisture and temperature as well as increased leaf litter [19]. However, on a daily timescale, entrainment of air masses from the FT and vertical transport caused by turbulent fluxes seem to have a greater influence on the early morning temporal evolution of CO\({}_{2}\) concentration in the ABL than plant uptake from photosynthesis [20,21]. Land use and land-management practices also influence vegetation and carbon dynamics within the ABL. Annual burning in grasslands of the Great Plains is practiced in part to control the expansion of invasive species, such as _Cormus drummondii_ (roughleaf dogwood) and _Juniperus virginiana_ L. (eastern red cedar). [PERSON] and [PERSON] [22] found that controlled annual burning of grasslands increases carbon loss compared with biennial burning, especially at times of above average precipitation. Shrub and tree encroachment leads to increased short-term carbon storage above ground, but these pools are vulnerable to fires and changes in land use. In addition, water availability, vegetation distribution, and rooting depth are important factors in ecosystem carbon dynamics related to woody encroachment [19,23]. Variations in photosynthesis and respiration that drive the larger amplitude of diurnal and seasonal carbon cycles associated with vegetation growth and senescence within the ABL are captured by eddy covariance (EC) tower measurements [24]. In an effort to advance studies of carbon dynamics, national and international observatory networks, such as AmeriFlux, FLUXNET, and the National Ecological Observatory Network, Inc. (NEON), have been established to combine local surface measurements from over 400 EC towers worldwide [24]. Though the average footprint of towers is on the order of 1 km\({}^{2}\), these surface measurements have been used to up-scale CO\({}_{2}\) concentrations and fluxes to provide estimates of gross primary productivity (GPP) and net ecosystem exchange (NEE) on regional to continental scales [25,26]. Estimations of NEE obtained through various \"top-down\" and \"bottom-up\" approaches remain restricted by the lack of theoretical knowledge in scaling nonlinear processes related to ecosystem fluxes [27,28]. Comparisons of surface and atmospheric measurements are key to understanding CO\({}_{2}\) concentrations and flux dynamics within heterogeneous landscapes and complex, nonlinear processes related to carbon cycling and climate change. Satellite measurements of atmospheric CO\({}_{2}\) concentrations from instruments such as the Atmospheric Infrared Sounder (AIRS) need to be evaluated in relation to ecosystem fluxes to improve assessments of NEE on varying spatial scales.