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So, what’s so special about the Red Sea Outflow?. Red Sea. Bab el Mandeb. Aden. Hartmut Peters Bill Johns Amy Bower Steve Murray Dave Fratantoni Silvie Matt. Djibouti. Gulf of Aden. … major factors that make the Red Sea outflow special …
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So, what’s so special about the Red Sea Outflow? Red Sea Bab el Mandeb Aden Hartmut Peters Bill Johns Amy Bower Steve Murray Dave Fratantoni Silvie Matt Djibouti Gulf of Aden
… major factors that make the Red Sea outflow special … • Topography (two narrow channels, rotation unimportant) • Seasonal variability • Short-termvariability • Low latitude • …
Northern Channel: ~130 km long, typically 5 km wide, 200-800m water depth, densest product water, slope: 1/3°. Southern Channel: shorter, wider, less dense product water.
Northern Channel: Relatively undiluted water along 120 km in bottom layer.
Dilution along the plume path: less dilution near bottom than for the whole plume
Vertical structure: • Mixed bottom • layer (BL) • Stratified & • sheared interfacial • layer (IL) IL BL
Fraction of plume transport in bottom layer: transport in interfacial layer increasing with downstream distance:
Plume flow in narrow channels… • Bottom Layer (BL): • stays relatively undiluted. • Interfacial Layer (IL): • - mixing, • - carries most of the entrainment, • - with increasing distance from the source, carries • carries an increasing and dominant fraction of the • total transport. • Do the other plumes show the BL / IL structure? • (The Med Outflow seems to.) • How much of the IL “counts” toward the product • water? How much of it ends up in the deep ocean?
Blue: plume Green: ambient waters
“The Table” is written in terms of bulk properties (for good reasons), but models need to parameterize mixing in terms of the gradients in the interfacial layer (+ possibly a bottom bulk mixed layer)
Mixing in the IL vs. bulk Froude number… Exponential fit: R2 = 0.47
Complex flow at the source • Mixing product from the flow through Bab el Mandeb
Three mixing products(Bab el Mandeb, two channels) • Detrainment: outflow water peels off on the top of the plume • Seasonal variability
Detrainment: Peeled-off outflow water
Red Sea Outflow at the Hanish Sill: - Transport & salinity - Seasonal and short-term variations - Tides
Perim Narrows Velocity 1995-96 Winter: 2 layers, outflow at bottom, inflow at top Summer: 3 layers, inflow in the middle, outflow at top and bottom (weak)
V • - Moored observations • 1995-96: • Northern Channel • Southern Channel • Seasonal variations • Short-term variations T S
Short-term variations during Redsox-1 Redsox-1
It’s a long way from Bab el Mandeb to the open Indian Ocean …
Horizontal homogenization of Red Sea Water by mesoscale eddies in the Gulf of Aden (Bower et al., 2002)