Significant Surge of Saharan Dust Moving Off African Coast

After being affected by mild to moderate Saharan Dust plumes year-to-date for 2021, the first major surge of dust has left the African coast on Tuesday 16th February 2021. This dust plume is forecast to decrease in concentration as it moves across the Atlantic Ocean. Still, some of the highest dust concentrations for 2020 are forecast to begin affecting T&T on Monday 22nd February 2021.

In the interim, over the next 5 days, air quality is forecast to be mostly good levels as low levels of Saharan Dust concentrations remain present across T&T and the Windward Islands.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in Trinidad and Tobago as of Saturday night. 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

Between Wednesday 17th February 2021 through Sunday 21st February 2021, no new surges of dust are forecast to arrive, with lingering mild concentrations present across T&T. The air quality will generally be at good levels, though it may dip to moderate levels in areas with high traffic or fires occur.

While mild dust concentrations will begin to increase from Sunday, from Monday 22nd February 2021, significant Saharan Dust concentrations are forecast to move across T&T, with an initial peak on Monday and then again on Thursday. High concentrations of dust will remain across T&T and much of the Eastern Caribbean through the end of February.

Based on the latest dust modeling, air quality across Trinidad and Tobago from Monday will vary between moderate to unhealthy for sensitive groups levels, particularly in areas where high traffic or fires occur.

00Z Wednesday 17th February 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust. (Weathermodels)
00Z Wednesday 17th February 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust. (Weathermodels)

What does this mean for you?

For the general population through the weekend, with mild Saharan dust concentrations forecast, little to no impacts are forecast beyond slightly 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.

For next week, 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. 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, and the Intertropical Convergence Zone (ITCZ) 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 and affect the Eastern Caribbean.

These Saharan Dust outbreaks tend to be milder in the Eastern Caribbean than the dust outbreaks associated with West African thunderstorms driving dust into the upper atmosphere from April through November.

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