Table 1 Parameter of the FIDES inverse dispersion model used to compute the chlorothalonil flux F and its uncertainty with Eq. (2). The Monte Carlo method used each parameter’s mean and standard deviation to quantify the uncertainty in the flux F.

Roughness length z₀

m

0.0035^*

0.0004^*

Measured log-normal distribution⁴⁹

Displacement height

m

0.15–0.44^#

0.03

Measured normal distribution⁴⁹

Sensor location (x, y,z)

(m, m, m)

variable

(1,1,0.1)

GPS positioning error in x and y and soil roughness in z

Friction velocity u_*

m s⁻¹

measured

14% ^$

Spatial variability of u_* as reported by⁹²

Wind direction

deg/N

Variable

12.5 deg

Measured spatial standard deviation among 3 sensors

Obukhov length L

-

Variable

40% ^$

Computed assuming a 14% error on both u_* and H

σ_w ^£

m s⁻¹

Variable

14% ^$

Assumed similar in magnitude to u_*

\(\:C\)

ng m⁻³

Variable

14% ^$

Uncertainty based on calibration curve (Supp. Figure 8)

\(\:{C}_{bgd}\)

ng m⁻³

5.7

2.2

Concentration measured during 2 days before application