Given zOffsets, diffusivity, and co2 (umol mol-1) and their associated errors, compute the surface flux. This is done by computing the gradient of co2 (slope from linear regression) and linear extrapolation of surface diffusivity. Modified from Tang et al (2003).
tang_2003_flux(zOffset, co2, co2_err, diffusive, diffusive_err)Data frame of fluxes associated error
Required. depths below surface - assumed to be positive in value. Important for directionality!
Required. co2 at depth (umol m--1)
Required. Associated errors with that value of co2
Required. diffusivity at each depth
Required Associated errors with diffusivity
John Zobitz zobitz@augsburg.edu
Tang, Jianwu, Dennis D Baldocchi, Ye Qi, and Liukang Xu. 2003. “Assessing Soil CO2 Efflux Using Continuous Measurements of CO2 Profiles in Soils with Small Solid-State Sensors.” Agricultural and Forest Meteorology 118 (3): 207–20. https://doi.org/10.1016/S0168-1923(03)00112-6.
Maier, M., and H. Schack-Kirchner. 2014. “Using the Gradient Method to Determine Soil Gas Flux: A Review.” Agricultural and Forest Meteorology 192–193 (July):78–95. https://doi.org/10.1016/j.agrformet.2014.03.006.
[dejong_shappert_flux()], [hirano_flux()], [tang_2005_flux()] for other ways to compute surface fluxes.