Concentrations of Saharan Dust remain mild across Trinidad, Tobago and the Lesser Antilles with rainfall improving air quality across the region. There are no major surges of Saharan Dust forecast to arrive across the Lesser Antilles through the next 7 days. We continue to monitor the La Soufrière Volcano eruption as volcanic ash can reduce air quality and visibility across islands that experience ashfall.
On Monday morning, the Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good across Trinidad and Tobago. These measurements are based on PM2.5 (particulates the size of 2.5 micrometers and smaller, usually associated with increases in Saharan Dust, vehicle exhaust, and smoke) and PM10 particulates. Across the Lesser Antilles, mainly islands south of the French Antilles are experiencing degraded air quality.
Visibility at Piarco International Airport, Trinidad, and Crown Point International Airport, Tobago is at 10 kilometers and above.
The Saharan Dust Forecast
A mild surge of dust is forecast to arrive across T&T and the Southern Windward islands on May 8th, with a reinforcing moderate surge arriving on May 11th. From May 8th, air quality levels will fluctuate between good to moderate.
According to latest models, weak high pressure systems will be present in the Atlantic through the forecast period, with much of the Saharan Dust remaining in the East Atlantic.
What does this mean for you?
Members of sensitive groups may experience health effects. The general public is not likely to be affected. There is an increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease, and premature mortality in persons with cardiopulmonary disease & the elderly.
We’re in a period where a ridge of high pressure stays over the central Sahara Desert. The Intertropical Convergence Zone (ITCZ) also remains over the Gulf of Guinea. The Harmattan wind accelerates when it blows across the mountain massifs of Northwest Africa. If its speed is high enough and it blows over dust source regions, it lifts the dust and disperses it.
Dust that makes it into the upper levels of the atmosphere can then get transported across the Atlantic Ocean. The plumes of dust eventually affect the Eastern Caribbean.
However, as we progress through May, the ITCZ and tropical waves may shield Trinidad and Tobago from the Saharan Dust events. While tropical waves play a notable role in moving dust across the Atlantic and the Eastern Caribbean, these frequent tropical waves also aid in improving air quality.
The concentration of the dust that follows the wave depends on the strength of the wave as it moves off the West African Coast. This is because of stronger thunderstorms across Central Africa. As strong winds move downward and outward from these thunderstorms, the wind kicks up dust as it moves across parts of the Saharan Desert and transports it into the upper atmosphere. This “plume” of dust follows the axis of the wave as it progresses westward into the Atlantic.
Larger, more concentrated plumes of Saharan dust begin to occur in April and continue through November.