Mariah is pronounced ma-rye-ah. It was also popularized by the singer Tom Waits in the song 'Big, Black Mariah', which was about a car. The song has also reportedly come from 'the deep South', in the USA, during the 1800's (?). It was then said to be about a 'dark wind' that blew over the Cotton fields.
"Ma-rie-a" is the older English pronunciation of "Maria." It is no doubt due to the influence of other European languages that "Ma-ree-a" is now far more common except in "They call the wind Maria" (no "h") and "Black Maria" (= "Paddy Wagon").
It's pronounced Ma-rye-uh
I personally don't like it.