Thursday 27 February, 2020

Met Office: Saharan dust may worsen this weekend

Trinbagonians suffering from allergies and other dust-related afflictions as a result of Saharan Dust should get a small reprieve soon.

The Trinidad and Tobago Meteorological Service said in an update on Wednesday that a mild amount of Saharan dust is currently present, however this may increase over the weekend.

(Video footage shared by the US National Oceanic and Atmospheric Administration in the first week of February 2019.)

However, the good news is that the dust plume would decrease somewhat from Monday, February 18, 2019.

Persons prone to asthma and other respiratory conditions are urged to take precautions such as:

- Wearing a dust mask or medical mask

- Staying indoors with windows and doors sealed against dusty conditions

- Staying hydrated 

- Changing bed linens regularly to prevent dust from distracting sleep patterns

- Keeping eye drops handy and wearing sunglasses to prevent dust from irritating eyes

- Placing a mat under doors to prevent dust from entering the home

- Keeping relevant medication handy such as asthma inhalers, sinus medication, pain relievers etc.

Please consult with your doctor to ensure you or other vulnerable persons are protected adequately from dusty conditions.


What is Saharan Dust?

The Saharan Air Layer (SAL) is an extremely hot, dry and dust-laden layer of air that originates over the Sahara Desert of North Africa, where it extends from the surface upwards to several kilometres. It is fed by strong low to mid-level easterly winds over the desert which pulls sand and dust particles into the atmosphere. This is where the dust haze really emanates from.

This layer of dusty, very dry and warm air is pushed westward by the easterly winds and, on reaching the west African coast or eastern Atlantic Ocean, it rides over the cooler, more moist surface air of the Atlantic Ocean, forming what is called an atmospheric inversion layer or boundary: with warm, dry air aloft and cooler, moist air below.  

The SAL has been observed to suppress the formation and intensification of tropical cyclones and can make tropical waves appear ragged or even disintegrate them due to the mixing of the SAL’s dry air into these weather systems. 

This is because the SAL typically contain lots of dry air, aerosol dust particles, and strong winds, all of which act against the development of cloud and tropical cyclone formation.

Once the SAL reaches the Atlantic, the easterly trade winds continue to carry this dust across the Atlantic at the lower and mid-levels, where eventually some of it, oftentimes large pools of it, lands over Trinidad and Tobago and the southern Caribbean.

As the SAL moves westward, it maintains the characteristics of warm stable air at its base, and dryness and dustiness throughout its vertical profiles. 

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