ocean currentsSurface current > 10% of ocean - wind driven - above pycnocline Depp current >90% - density driven - below pycnocline
Trade winds Westerliestrade winds between 0°-30° blow currents to the west westerlies between 30°-60° blow surface currents to the east
molecular viscosity eddy viscosotya) laminar flow: momentum transfer between molecules of different layers b) turbulences in currents so not individual molecules moved but parcels of molecules > lead to higher friction
Gyresrespond to main ind belts main gyres (5) North and south pacific north and south atlantic indian
wind stress in generalits a friction force (horizontal force)/per unit of area > influenced by: prevailing atmospheric conditions, wind speed, roughness of the sea surface >wind stress causes transfer of momentum: a) surface ...
eddy viscosity coefficienthave in vertical direction (Az) and in horizontal (AH) horizontal value is much higher because ocean is very stable in the vertical and a lot more mixing occurs in the horizontal
Ekamn theory Force equilibriumWhen wind starts to move it induces movement in the surface. Due to coriolis force current deflects to the right the current velocity is constant when coriolis force, wind induced force and friction ...
ekman theory - wind induced circulation - Conditions ...developing a model ocean > no horizontal eddy coeffizient and vertical is constant >barotropic conditions (no differences in density horizontal) > no horizontal pressure gradient > no slope in surface ...
ekman velocitycurrents velocitiy only induced by wind - seperate from geostrophic current - fv = f(vekman + vgeo)
ekman velocity calculation and at equatorvelocity decades exponentially with depth _spiral when z= DE (depth of ekman layer) the current moves oppisitional to wind at equator f=0 so not solvable > no ekman spiral at equator
ekman depthhere the current is directly opposed to wind and its velocity is 1/23 of the surface thus neglible the depth depends on the eddy viscosity coefficient and the latitude the direction of the stream in ...
mean ekman transport90° to the right from the wind = net movement and water from bottom rises up in a spiral
bottom friction and geostrophic velocitythe bottom friction reduces the geostrophic currents velocity thus coriolis forces alo decreases and the current deflects back to the left. balanced again when deflected 45°
ekman pumpingwind moves cyclonic (anticlockwise) the ekman transport is nach außen > divergence and water needs to be replaced by bottom water = upwelling > Ekamn suction wind moves anticyclonic - ekman transport ...
geostrophic current in the gyreanticyclonic = convergence : right: geostrophic current goes out and on the left side goes in opposite for cyclonic
western intensificationcenter of gre is moved to the west due to wearth rotation >intensification in the western currents
equatorial upwellingmathematically ekman transport not working at equator, however, it can be observed: trade winds lead to divergence thus upwelling. geostrophic current moves same direction bc of deflection change due ...
main upwelling regiona)canary current b)peru current c) benguela current d)california current
wind stress curlpositive: offshore stronger wind thus ekamn transport also stronger which leads to divergence and thus more upwellling negative: offshore wind is less thus ekmann transport is less which leads to convergence ...
relaitve vorticity= der vertikale teil aus dem kreuzprodukt des gradienten und der geschwindikeit = vorticity ist perpendicular zur horizontal geschwindigkeit
3 types of vorticity• Absolute vorticity ( ~ωa) = vorticity as viewed in an inertial reference frame.• Relative vorticity (~ζ) = vorticity as viewed in the rotating reference frame of theEarth.• Planetary vorticity ...
f-plane beta-planef-plane = f is constant β-plane - f changes with latitude - vorticity changes with latitude
continuity equationin fluid dynamics describes that in any steady state process, the rate at which mass leaves the system is equal to the rate at which mass enters a system
potential vorticity(rel. vorticity + f)/D > conservation of potential vorticity as it is constant thus when D decreases, rel. vorticity decreases and anticyclonic vortex when D is increasing rel, vorticity needs to ...
conservation of potential vorticitywhen die layer (D) kleiner wird dann muss rel. vorticity auch kleiner werden (-) = anticyclonic vortex when D increases rel. vorticity has to increase (+) = cyclonic movement
langmuir circulationtransient wind induced horizontal tubes below surface. >cells formed when small surface waves are damped one cell moves clockwise and the adjecent tubes moves counterclockwise resulting in a up and downwelling ...