Brief, High-Concentration Surge of Saharan Dust To Move Across T&T

Air quality is forecast to decrease across Trinidad and Tobago over the next 48-72 hours as a brief but high-concentration surge of Saharan Dust moves across the region. While higher concentrations are forecast to remain north of the country, visibility and air quality will be markedly reduced compared to the last two weeks.

Over the last 24 hours, air quality has been good with visibility near and above 10 kilometers across Trinidad and Tobago. The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good across the country. 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.

The Saharan Dust Forecast

By Wednesday, Tropical Wave 43 is forecast to move across the region, with Saharan Dust following by the late afternoon. Dust concentrations will increase and remain at elevated levels until late Friday, as Tropical Wave 44 briefly improves air quality on Saturday into Sunday.

Mild concentrations of Saharan Dust will linger across the region through the weekend, with higher concentrations remaining across the Leewards. Another moderate to high-concentration surge is forecast to move across the region next Friday.

Air quality levels are forecast to remain good levels until mid-Wednesday, becoming moderate and continuing into the weekend. On days with peak concentrations, visibility may be reduced between 7-10 kilometers.

12Z 7th September 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.
12Z 7th September 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.

What does this mean for you?

For the general population, with moderate to high Saharan dust concentrations forecast, little to no impacts are forecast beyond hazy skies. For sensitive groups, such as children, the elderly, and persons who suffer from respiratory ailments and allergies, you may need to avoid prolonged exertion outdoors on days with high concentrations of Saharan Dust.

We’re in a period where the ITCZ and tropical waves may shield Trinidad and Tobago from significant dust events. While tropical waves play a notable role in moving dust across the Atlantic and the Eastern Caribbean, these periodic tropical waves also improve 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.

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.

Larger, more concentrated plumes of dust begin to occur in April and continue through November.

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