Land based sources of pollution//source estimates
Alina M. Szmant
szmanta at uncwil.edu
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
areas?
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
>>equatorally
>>driven!?
>>
>>We hope to be looking at this more closely in the years ahead...
>>
>>Cheers,
>>Al
>>
>>"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/NESDIS/ORA/ORAD -- E/RA3
>> NOAA Science Center -- RM 711W
>> 5200 Auth Road
>> Camp Springs, MD 20746-4304
>> Alan.E.Strong at noaa.gov
>> 301-763-8102 x170
>> FAX: 301-763-8572
>> http://orbit-net.nesdis.noaa.gov/orad
>
~~~~~~~
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