BIPM Virtual Workshop on Accurate Monitoring of Surface Ozone

5-9 October 2020 (online)

Implementing a Globally Coordinated Change in Ozone Cross-Section Value
for Surface Ozone Monitoring

Workshop Executive Secretary

Steering Committee

Objectives

The reference method for ground-level ozone measurements is based on UV photometry, with replicates of the NIST Standard Reference Photometer (SRP) acting as primary standards for numerous national and international ozone-monitoring networks. Measurements of ozone amount fractions in ambient air are thus ultimately anchored to the value of the ozone absorption cross-section at the wavelength 253.65 nm. A consensus value with the smallest uncertainty ever achieved was published in 2019.

Global coordination is now required to implement the 2019 value, which will increase the measured atmospheric ozone concentrations. The workshop aimed to gather representatives of reference laboratories, monitoring networks, legislators, and ozone analyser manufacturers to develop a plan and timetable for the adoption of the 2019 value.

Schedule

The virtual workshop included five on-line sessions from Monday 5 to Friday 9 October 2020, each session starting at 12:00 (UTC+2):

• Monday: Surface ozone measurement and its impact / Survey feedback
• Tuesday: International standards, calibration services and monitoring networks
• Wednesday: Air quality normative aspects; ozone analyser manufacturing
• Thursday: Break out session for Task Groups
• Friday: Feedback from Task Groups, conclusions and recommendations

CCQM-GAWG Statement

Following stakeholder consultation during the Workshop, the CCQM Gas Analysis Working Group is issuing a statement on its intention to change the Ozone Cross-Section Value used for Surface Ozone Standards and Measurement.