These animations show the predicted ground-level pollution caused by the Gloucestershire incinerator during 2018, assuming the incinerator had been emitting continuously during that time and sticking to the permitted maximum concentration of nitrogen oxides (NOx). In practice, most existing incinerators emit NOx at only slightly below (about 75% to 100% of) the permitted concentration. Animations are created by modelling the incinerator plume every hour during a period of time, using historical local weather data.
|30km x 30km||15km x 15km|
These animations were produced in January 2019. They differ from the animations released in 2015 in several ways:
The specification of the incinerator changed, from this (2012) to this (2017).
The simulation uses a new, more accurate, model of the incinerator buildings. Modelling buildings is very important because they cause downwash, which depresses the plume in certain winds. This is especially bad when the buildings are high or close to the stack, as they are in the case of this incinerator. The 2015 animations modelled the incinerator as three buildings (here); the new animations model it as 12 buildings (here), to account for the strangely sloping high roof closest to the stack. (Only flat-roofed buildings can be modelled, so we approximate the sloping roof by 8 "steps".)
A different source of weather data was used: Elmbridge instead of Quedgeley. Five weather sources were examined in detail: Gloucestershire airport, Bristol airport, and amateur weather stations at Elmbridge, Quedgeley and Lansdown. Gloucestershire airport is local but only reports weather part-time. Bristol airport is unsuitable because wind directions (and speeds) are very different. Elmbridge and Lansdown report wind directions very similar to Gloucestershire airport, while Elmbridge (but not Lansdown) also reports similar wind speeds. Therefore, we use Elmbridge for wind and temperature data. Cloud cover data is taken from Gloucestershire airport when available and Bristol airport at other times.
|Bristol airport||4.88 m/s||232.7°|
|Glos airport||3.39 m/s||220.8°|
The live plume plot works in the same way, except that wind and temperature data is currently taken from the Quedgeley weather station. Here is a description of how it works.
All plume animations are available on youtube.