Air quality and noise emissions are impacted by many factors, one of them being temperature inversions. This occurs when there is a warm layer of air on top of a cooler layer. Rising air from the earth’s surface reaches the warmer air ‘ceiling’ and cannot rise any further. Therefore, fumes and dust become trapped close to the ground and sound can be reflected off the ceiling, creating enhancing conditions for both air quality and noise impacts.
Inversions are likely to occur in the cooler months and typically happen after sunset and can last until 1-2 hours after sunrise. Inversions break up once the sun rises and warms the earth’s surface. Warm air rises and cools as it gets higher, creating a convection air flow. This disrupts the inversion layer, resulting in the movement of fumes and particles. This time in the morning is also when odours are most often detected and complaints about air quality are received.
Novecom has determined a method for forecasting inversions by analysing air temperature data obtained from a Meteorological Temperature Profiler (MTP). MTPs measure the temperature profile up to 1,000 m at intervals of 25-50 m. The team at Novecom have identified a relationship between the summation of positive temperature changes over time and the persistence of an inversion. The derived parameter was termed ‘Delta sum’.
Novecom’s SentineX data acquisition and reporting platform can be configured to provide a prediction of the likelihood, strength and duration of inversions. Plant operators can receive notifications to tell them when an inversion is likely to occur and how severe it will be.
The strength of the inversion is measured according to the lapse rate, or change in temperature per unit of height. Definitions vary, but for Novecom client Collinsville Coal a moderate inversion is defined as a temperature differential of ≥ 1.5⁰C and ≤3.0⁰C per 100 m. A strong inversion is defined as a temperature differential of ≥ 3.0⁰C per 100 m.
Armed with this information, we can better manage the impacts of temperature inversions, including down-time in mining, chemical processing and other industrial manufacturing processes. We can figure out more accurately when to avoid or limit emissions, thereby reducing air pollution and protecting communities.
Novecom can provide a complete inversion monitoring, reporting, and forecasting solution that incorporates the MTP and is supported by the SentineX data analytics platform.