The NRT (near real-time) plot shows three types of Dobson observations collected in the past month: ADDS (direct sun, blue circle), ADZB (zenith blue, orange circle) and ADZC (zenith cloud, red circle) ozone column (DU) is derived from the AD wavelength pairs. The solid blue line is the Dobson's daily averaged ozone between 1966 and 2019 and the light blue envelope is the 2 standard deviations.

The solid green line represents the daily averaged ozone over the ground station that is delivered by the NOAA operational processing of the S-NPP OMPS V8 nadir mapper products. The light green envelope represents the max and min range of total ozone observations provided by the NOAA operation version of S-NPP OMPS V8 nadir mapper. Ozone is reported as a distance weighted average value for all observations found within the box of: +/- 0.5 deg in latitude and +/- (1/cos(lat*pi/180)) in longitude centered on the station latitude/longitude. The NOAA NPP/OMPS data can be found here:

The dark small dots and thin line is the NASA version of the JPSS S-NPP OMPS satellite overpass data matched with Dobson location. The ozone value is reported at the "closest distance" to the respective station. This is the closest ozone value to the station and has not been averaged. The value even gets reported on days that the averaged value gets reported as zeros. The NASA NPP/OMPS data can be found here:

Additional charts below the total ozone plot provide information from NASA NPP/OMPS version output:

Dist. : Distance between the station and the CTP (km)
SZA : Solar Zenith Angle (degree)
O3blwCld : Ozone below fractional cloud (DU)
Cld. F. : Radiative cloud fraction (dimensionless)
AI : UV Aerosol Index (dimensionless)
SOI : SO2 Index (dimensionless)