BIO 475 Lecture Notes - Lecture 14: French Frigate Shoals, Solar Irradiance, Benthos
Reef Hydrodynamics 10/3/17
● 1st Graphic; absorbed solar radiation
○ Tropics get a lot more light
○ What's the mean solar insolation? Low at poles, and high at the tropics. ( bell
curve on its side; 2nd graphic)
● 3rd graphic; Warm tropic area → the heat rises from the surface of the earth into the
atmosphere, tends to go north or south. Top of ATM winds going S/N away from equator
○ Surface of the earth got winds going towards the equator
○ Trade winds: blow 24/7 , keep areas cool , because the sun is heating the earth
, winds bend due to coriolis effect.
● 4th,5th Graphic; French Frigate Shoals
○ North up. Northern hemisphere, trade winds coming from NE to SW
○ Windward; Facing wind
■ Alot more reef, more wave action
○ Leeward; Away from win
● 7th,8th; Fiji
○ SE to NW
○ Still more reef on windward side
● Atoll Circulation
○ NE trade winds
■ Push water/waves across reef into the lagoon
■ Some atolls can have higher sea level inside atoll than outside due to
winds pushing water in, if winds stop water sloshes back out
■ South channel water always coming out
■ Deep entrance, water comes in with incoming tides and out with outgoing
tide
■ Hashmarks, not alot of strong water flow one way or another
■ All along built up reef, water comes with winds
■ Fetch outside atoll big, inside small
● Lagoonal surface currents (don't have to draw it)
○ NE trades
○ Explain what it means
○ Complex patterns, water is flowing from East to west in general, but not always
the case. Some differences where tidal currents are
○ Implication: Water flow(nutrients), larvae dispersal
■ Most currents go inside atoll
● LAgoonal mid-depth and deep currents
○ Circulation at surface isn't going on the same underneath
○ How do long do materials stay there
● Flow at a reef scale
○ Winds →
○ Water piling up raises sea level on reef crest; wave setup
○ Extra water, literally flows down hill on water
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Document Summary
Low at poles, and high at the tropics. ( bell curve on its side; 2nd graphic) 3rd graphic; warm tropic area the heat rises from the surface of the earth into the atmosphere, tends to go north or south. Top of atm winds going s/n away from equator. Surface of the earth got winds going towards the equator. Trade winds: blow 24/7 , keep areas cool , because the sun is heating the earth. Northern hemisphere, trade winds coming from ne to sw. Push water/waves across reef into the lagoon. Some atolls can have higher sea level inside atoll than outside due to winds pushing water in, if winds stop water sloshes back out. Deep entrance, water comes in with incoming tides and out with outgoing tide. Hashmarks, not alot of strong water flow one way or another. All along built up reef, water comes with winds. Lagoonal surface currents (don"t have to draw it)
