Comparing a Non-Gradient Model to Nocturnal Eddy Covariance Measurements of Trace Gases Over Land Surfaces

The eddy covariance technique is widely known and used to estimate trace gas fluxes between the surface and atmosphere. However, literature has shown that nocturnal estimations from the eddy covariance method systematically underestimate long term carbon fluxes with possible sources of error including intermittent turbulence and drainage flows. In the past few decades, non-gradient models (NGMs) have been used to estimate fluxes. These studies include NGMs of ground heat flux, mass flux, and most recently, gas fluxes over land. This work will compare a NGM to nocturnal eddy covariance measurements from the from the 2018 Stable Air Variability and Transport (SAVANT) field campaign. Eddy covariance measurements from four different towers over agricultural fields will elucidate the impact of drainage flows on flux estimation. The NGM method provides an alternative process for studying gas fluxes over land surfaces using less inputs than other models.