Nominal Uncertainties

The nominal uncertainties in the Earth Probe TOMS near real-time data products are summarized in the tables below:

Uncertainty in Earth Probe TOMS Ozone

Uncertainty in:

Nominal

Solar Zenith Angle > 80

Absolute Value

3%

4%

Precision

2%

5%

Long-term Mean

1%

1%

Uncertainty in Earth Probe TOMS Reflectivity and Aerosol Index

Uncertainty in:

Reflectivity at Low Reflectivity

Reflectivity at High Reflectivity

Aerosol Index
(331 nm Residue)

Absolute Value

0.008

0.015

0.30

Precision

0.002

0.003

0.15

Long-term Mean

0.005

0.01

0.1

The effective Lambertian equivalent surface reflectivity and the aerosol index are not physical quantities. Because of this, no algorithmic error sources have been included. Nominal instrument calibration errors of 1.5% at 360 nm and 0.75% at 331 nm relative to 360 nm have been assumed. Evidence of uncorrected diffuser degradation drives the errors in long-term mean for the reflectivity and aerosol index, but there is no significant effect on derived ozone.

More information on error sources is found in the EP TOMS Data Products User's Guide.