Land based sources of pollution//source estimates

Alina M. Szmant szmanta at
Thu Oct 4 11:47:31 EDT 2001

Really interesting stuff!!!  The increase in winds 21-30 km/h would be in 
the range that could result in a lot more resuspension of finer sediments 
(i.e. turbidity).  Anyone doing such analyses for the Caribbean and Florida 

Alina Szmant

At 09:47 AM 10/04/2001 +1000, William Skirving wrote:
>Hi Al and others,
>Yes we have found that the wind in the GBR region has been increasing 
>(we've only looked at summer winds over the past 50 years).  We think that 
>it is because we are getting more highs and lows over our region during 
>the summer, rather than having dominant lows.  The transition between a 
>high and low gives rise to increased pressure gradients and hence 
>increased winds.  This has been a steady increase over the past 50 years 
>and seems to be correlated with increased temperatures (ie global 
>warming).  This is only statistical yet, and we have yet to put our finger 
>on the exact cause.
>The high pressure events seem to be associated with increased ridging up 
>the east coast of Australia, which is also a typical ENSO response.
>Now for the interesting stuff.  There is a significant decrease in winds 
>0-10 km/h, a slight decrease in winds 11-20 km/h, a significant increase 
>in winds 21-30 km/h, a slight increase in winds 31-40 km/h and no 
>detectable change in winds greater than 40 km/h.
>So yes, we are seeing a change in winds which seems to be associated with 
>global warming.
>This has interesting implications for coral bleaching, since more wind 
>means more mixing, more mixing can mean less extreme SSTs and therefore 
>potentially less coral bleaching!
>William Skirving
>At 01:25 PM 10/3/01 -0400, Alan E Strong wrote:
>>Alina -- An interesting observation.....Folks we have been working with 
>>in the GBR
>>see evidence of increased pressure offshore in the recent decade....does 
>>this mean
>>greater sea-breezes from increased ocean-land temperature/pressure 
>>differences?  It
>>may also have something to do with PDO...that the latest GRL tells us is 
>>We hope to be looking at this more closely in the years ahead...
>>"Alina M. Szmant" wrote:
>> > Bob and others:
>> > ...
>> > I have a hypothesis that I have been bandying around for a few years that
>> > it's been more windy since the mid 1980s and 1990s which could be an 
>> effect
>> > of global warming (more heat, more wind) [this is based on a gut 
>> impression
>> > that in spite of having bigger and better boats than I had access to 
>> in the
>> > 1970's, we have more days that we are weathered out now than a few decades
>> > back].   More frequent or more severe storms all year long could result in
>> > lower overall water clarity in areas like the Florida Keys where there is
>> > lots of sediment to resuspend (I gave a presentation about all this in
>> > Bali, but mea culpa, mea culpa I haven't written it up yet).  If those of
>> > you that like to work with climate data would have access to good wind
>> > records, I suggest someone look at the frequency and duration of higher
>> > wind events over the past 50 years or more, by passing the data thru some
>> > kind of filter that looks for the higerh energy events (e.g. 15+ knots for
>> > 24+ hrs):  it takes a minimum period of high winds to really get things
>> > stirred up, but if the rough conditions persist for too long, suspended
>> > sediments are likely flushed out of the system).  Thus, not enough
>> > resuspension could result in fine sediments building up to eventually
>> > become a problem (nutrients will also build up); frequent moderate energy
>> > events may make the system turbid a lot of the time depending on whether
>> > net flow rids the system of the resuspended fines; occasional major events
>> > help flush the system of both sediments and nutrients.  Thus wind regimes
>> > (and their change over time as climate changes) could make a big 
>> difference
>> > in the environment conditions reefs have to deal with, and their "health".
>> > ...
>> >
>> > Alina Szmant
>>**** <>< ******* <>< ******* <>< ******* <>< *******
>>Alan E. Strong
>>Acting Chief, Oceanic Research & Applications Division
>>Team Leader, Marine Applications Science Team (MAST)
>>Phys Scientist/Oceanographer
>>   NOAA Science Center -- RM 711W
>>   5200 Auth Road
>>   Camp Springs, MD 20746-4304
>>         Alan.E.Strong at
>>              301-763-8102 x170
>>               FAX: 301-763-8572

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