Fig. 4. Eddy covariance measurements of CO₂ flux above a parking lot for 7 d in July 2002. Shown are uncorrected raw measurements and the same data after density corrections have been applied. Actual fluxes of CO₂ from the surface were approximately 0.04 mg m^-2 s^-1 (dashed line). Downward fluxes are negative; upward fluxes are positive.