[Coral-List] Sea Surface Temperature, bleaching, hurricanes and African dust

scott.stripling scott.stripling at noaa.gov
Fri Sep 22 05:45:33 EDT 2006

Gene, Coral listers

The following links will take you to NOAA and NASA articles on this joint
project that Gene makes reference to. Actually, NASA and a wide ranging 
of international scientists are conducting their work on the African 
monsoon circulation
and meteorological aspects from western African and the Cape Verdes,
while NOAA is launching flights into the environment surrounding tropical
systems and the traversing Saharan Air Layer (SAL) from this side of the 


As you say, this is not peer reviewed science. However, we have seen a 
amount of dust (locally) this season, and this *HAS* likely been a 
factor in inhibiting tropical
cyclone formation, not due to cooler SST's but due to the ingestion of 
SAL into
the circulation of the tropical waves attempting to organize and 
intensify into
tropical cyclones. The cooler SST's this year, in my opinion, are due to 
than normal high pressure across the Atlantic basin leading to a 
persistent and
strong trade wind flow across much of the tropical and subtropical Atlantic
and NE Caribbean. These strong trade winds act to mix the upper layer of 
the ocean
and thus keep upper layer temps in more typical ranges. Although in this
warm Atlantic "cycle" we appear to be in, peak summer SST's may reach
alert levels almost annually for the coral reef community throughout the 
decade or two, I would suspect that major NE Caribbean bleaching events 
tend to be realized when the trade winds are weaker than normal throughout
much of the summer, as was the case last year.

Scott Stripling
NOAA-NWS San Juan, Puerto Rico

Gene Shinn wrote:
>     Those of you concerned about Atlantic/Caribbean sea surface 
> temperature, coral bleaching, and hurricane formation may find the 
> article by Kim Kavin in the October, 2006, issue of Power and Motor 
> Yacht p. 99, of some interest. The first few paragraphs of the 
> article are transcribed below. The remainder of the article, not 
> reproduced, is mainly about boat chartering.
>      (There was so much dust in the air in St. Thomas this summer that 
> Pamela Wilson could taste it. "You can hear it in my voice," she said 
> in early July. "I can't breathe."
>      For a lot of people, this would be an uncomfortable 
> inconvenience, but for Wilson, the implications were huge. As the 
> general manager of the charter firm Flagship in the U. S. Virgin 
> Islands, Wilson has the duty of scheduling charter vacations and 
> keeping the company's fleet of boats out of harm's way -and she 
> believed the dust had a lot to do with the impending hurricane season.
>       "When we have a lot of Sahara dust, we don't tend to get a lot 
> of storms," she explains.  "When the sandstorms start in Africa and 
> move off the coast, that's when they become tropical lows. That's 
> what makes the depressions. If we get a lot of dust early in the 
> year, it seems to keep the number of storms down."
>       Scientifically speaking, the dust keeps sunlight from 
> penetrating the water, which keeps the water temperature cooler - 
> less than ideal for gathering storms. When Wilson was describing the 
> dust in the air, she also noted that the water temperature in St. 
> Thomas was lower than that in Florida and the Bahamas, where she, was 
> guessing the bulk of the late 2006 hurricanes would hit. She wasn't 
> alone. A growing number of insurance providers, yacht captains, and 
> charter brokers all believed the same thing-which is why an unusual 
> number of boats decided to stay in the Caribbean and offer charters 
> through October instead of cruising north to Florida, south to 
> Trinidad, or across to the Mediterranean to avoid traditional storm 
> routes.)
>       Coral-list readers will realize this magazine article is not 
> peer-review science and only describes what people in the Virgin 
> Islands have experienced each summer for the past 30+ years. However, 
> be advised that a NASA/NOAA project is underway in the Cape Verdi 
> islands off the west coat of Africa that is investigating the 
> meteorological relations between African dust and hurricane 
> formation. The project, to my knowledge, is not investigating the 
> viable microbes, insects, heavy metals, pesticides, short-lived 
> isotopes and nutrients in the hundreds of millions of tons of African 
> dust that cross the Atlantic each year. I expect we will be seeing 
> press releases and articles about results of this study in the near 
> future. Lets hope we do not experience the late season storms in the 
> Caribbean/Florida coral reef areas that have been predicted.  Gene

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