Forecast Methodology

How are the forecasts produced?

The air quality forecasts are provided by the Met Office on a daily basis, 365 days a year, for locations across Sussex. These forecasts are checked, and whenever there is a predicted exceedance of the “moderate” air quality banding, alerts are triggered and sent out to recipients.

The Met Office weather forecast and climate prediction model uses UK and European maps of annual average pollutant emissions to simulate the release of chemical species into the atmosphere. These are then allowed to chemically react according to prescribed reaction rates, which depend on factors including the concentration of the species, the temperature and the amount of sunlight. Species are then transported and dispersed within the model according to the winds, and the concentrations are re-evaluated. Using the concentrations calculated in this way throughout the forecast period, the Daily Air Quality Index is calculated as an average over prescribed time periods. We have found that our Air pollution forecasts can be improved by using recent observations of air quality from across the UK, together with our forecast model, to give an adjusted forecast. We, therefore, use observations from the Automatic Urban and Rural Network (AURN) as part of our forecast system. (Source: https://www.metoffice.gov.uk/weather/guides/air-quality-forecast).