How are Individual and aggregated (1-hour mean, 24-hour mean, ...) measurements calculated and what is their timestamp on Dashboard?

The Clarity Dashboard provides tools to view and download both individual measurements and aggregated data, including 1-hour and 24-hour mean values, as well as other specialized aggregations.

Individual measurements

These are the highest-resolution measurements, derived from single readings taken by a Clarity Node-S. They are timestamped to reflect the exact moment they were recorded, for example 12:56:21 UTC.

Aggregated measurements

1-hour mean measurements

Calculated by averaging all individual measurements collected during a specific UTC hour. For instance, the 04:00 UTC 1-hour mean aggregates all measurements taken between 04:00:00 UTC and 04:59:59 UTC.

24-hour mean measurements

Calculated by averaging all measurements collected over a complete UTC day. For example, the 24-hour mean for 2024-01-01 aggregates all measurements from 00:00 UTC to 23:59:59 UTC on 2024-01-01.

Other aggregations

Additional aggregations, such as the NowCast and 24-hour rolling mean, use different time windows to calculate averages and are reported hourly. These aggregations provide specialized insights into air quality trends:

  • NowCast aggregates measurements over a 12-hour window according to US EPA NowCast calculation rules, ending at the end of the reporting hour. For example, a PM2.5 NowCast concentration timestamped at 16:00 UTC includes data from 05:00 UTC to 16:59:59 UTC.
  • 24-hour Rolling Mean averages measurements over a sliding 24-hour window, also ending at the reporting hour.

Unlike aggregated measurements, individual measurements are not reported on a fixed cadence because the reporting interval of the Node-S can vary. For more details, click here.