Example 24: corr_irr2 - generic irradiance and PAR

This equation is a refined and simplified version of the one given in Example 23, and will typically be used to present irradiance in μW/cm2/nm, or PAR in μmol/m²/s.

\[Irr_{tempcompensated} = c_0 + c_1*c_2\left(R + x_0 + x_1*(T_{sensor}-x_3) + x_2*(T_{sensor}-x_3)^2\right)\]

Then applies a linear equation to convert to final units:

where

  • c0 is a user-adjustable dark offset value.

  • c1 is the primary slope coefficient which transforms the value to final units.

  • c2 is an immersion factor, which corrects for use in a medium other than was used for calibration; water compared with air, for example.

  • R is the raw voltage ratio measured by the logger.

  • x0, x1, x2 are factory-determined coefficients of a quadratic term, used to correct the sensor’s dark current for temperature effects.

  • x3 is the temperature at which the optical calibration was performed.

  • Tsensor is the internally measured temperature of the sensor in °C.

  • Irrtempcompensated is the final value of irradiance or PAR, temperature compensated and presented in final calibration units.

Examples

>> channel 3 type
<< channel 3 type = irr_05

Confirm the channel type.

>> calibration 3 datetime = 20210901085500, c0 = 0.000, c1 = 5079.0, c2 = 1.2

Set the core coefficients.

>> calibration 3
<< calibration 3 label = irradiance_00, datetime = 20210901085500, c0 = 0.000, c1 = 5079.0, c2 = 1.2, x0 = 0.098, x1 = 0.023, x2 = 0.00037, x3 = 23.4, n0 = 4

Request confirmation of all calibration coefficients.