Photo of scientist with a Dobson spectrophotometer

Lapenta intern Leah Barkai working on the Dobson D083 spectrophotometer. Photo by Darryl Kuniyuki.

Hosting the WMO/GAW World Dobson Calibration Center, GML is the custodian of the Dobson World standard instrument D083. Every two years, measurements were made at the Mauna Loa Observatory to derive the calibration constant.

The unique location of Mauna Loa Observatory is prime for the calibration of D083. Stratospheric ozone tends to be more stable in the tropics, and its high elevation is above the surface boundary layer, which reduces the presence of aerosols and pollutants that scatter light. This allows for more accurate measurements.

The collection of data for deriving new calibration constant is extended over a 2 months period during which only days with stable ozone and clear sky are selected for final analyses. If a new constant is warranted, all regional standards are updated by intercomparisons with D083, and the regional centers propagate the new calibration to the station instrument in a similar manner.

Read more at the NOAA Global Monitoring Lab website at the link below.