High Concentrations of Saharan Dust Present Across T&T

A surge of Saharan Dust arrived across T&T and the Lesser Antilles overnight, following a surge of trade winds which led behind the axis of Tropical Wave 10.

Peak concentrations are forecast today across T&T with concentrations declining into Tuesday. Back-to-back tropical waves and the Intertropical Convergence Zone is forecast to shield T&T from significant dust through the week, with a resurgence of dust forecast by the weekend.

Air quality through the next 24 hours is forecast to be moderate, but from Tuesday onwards, air quality may vary between good and moderate levels.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in 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.

The Saharan Dust Forecast

Through Tuesday morning, Saharan Dust concentrations are forecast to be high across T&T with air quality at moderate levels and visibility reduced between 7-10 kilometers.

As moisture ahead of Tropical Waves 11 and 12 moves across T&T, higher concentrations of dust will shift further away from the country, and air quality will improve through Friday. Though the tropical waves will keep moisture in the region through the week, dust models show another high-dust-concentration surge arriving on Friday into the weekend. Dust is forecast to linger through the end of June, with brief improvement as tropical waves move through the region.

Air quality levels will fluctuate between good to moderate. On days with peak concentrations, visibility may be reduced between 7-10 kilometers.

12Z 20th June 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.
12Z 20th June 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.

With high concentrations of Saharan Dust forecast, members of sensitive groups may experience health effects. The general public is not likely to be affected though visibility will be reduced due to increased dust. 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 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 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 Saharan dust begin to occur in April and continue through November.

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