Chapter 2 part 1 upwelling Flashcards
Upwelling:
- Rise of deep sea water to the surface (movement of water from deeper layers of the sea to the surface)
Upwelling
primary zones
eastern boundaries of oceans
upwelling is a ……………. of the sea
charactaristic
- Types of upwelling:
- Coastal (most common type)
- Large scale wind induced upwelling in the open ocean
- Upwelling related to tropical cyclones
- Related to topography
- Equatorial
- Benefits of upwelling
- Nutrient regeneration to the surface
compare the different types of upwelling in the coastal ocean
Wind driven
Causes
Topographic detail such as water depth and shape of coastline
Effects
Currents
Stratification
Nutrient supply
Dynamic uplifting (independent of coastal wind condition
Causes
Variation in the currents found outside the coastal ocean
In deep ocean Coastal upwelling occur where
The water movement is the result of: (coastal upwelling)
- Wind driven Ekman flow
- Geostrophic flow
water movemnt is Directed:
- At an angle away from the coast near the surface
- Parallel to the cost at mid depth bellow the Ekman layer but above the bottom boundary layer
- At an angle towards the coast in the frictional boundary layer at the bottom
Regions controlled by this dynamic (coastal upwelling)
- Subtropics where the trade wind blows toward the equator along the eastern coastlines of the ocean
Most related to human activities as it: (coastal upwelling)
- Supports some of the most productive fisheries in the world
coastal upwelling is normally due to
Stationary upwelling:
- Atlantic ocean (warmer water is supplied to the surface in the Beaufort sea upwelling)
- Canary (west African)
- Guinean
- Brazilian
- South African
- Indian ocean
- Bengal
- Somali
- Pacific ocean
- Chilean Peruvian
- Californian
- Oregon
- Arctic ocean (warm water is supplied to the surface along the northern margins of the Siberian arctic sea)
- Beaufort sea
Important areas of upwelling
- Middle part of the Caspian sea off the east coast in summer
- Black sea (south coast of crimea)
- Sea of Okhotsk (along the southwest coast of Kamchatka)
compare types of upwelling
Cause
coastal
wind blows parallel to the coast with the coast line to its left in the NH (alongshore wind)
Coriolis force
Wind driven Ekman flow
Geostrophic flow
Open sea
Currents diverge (related to prevailing winds)
Tropical cyclone
Cyclone vorticity separate the water and pulls colder water from the deep layers to the surface
Slow moving cyclones (up to 8km/h)
Topography
Islands, submerged ridges and mounts deflect Deepwater currents (small area & unsteady in time)
Equator
divergence at the surface at the equator
due to Coriolis force acting on the sides of equatorial currents
Upwelling in the open sea
causes
Currents diverge (related to prevailing winds)
Upwelling in the open sea
Process:
Upwelling in the open sea
Compare coastal upwelling and upwelling in the open ocean:
Rates that water ascend are less compared to coastal upwelling
Upwelling in the open sea
Disadvantage of the concept of upwelling in the open sea
It is poorly understood
Upwelling due to passage of tropical cyclone
Cause:
- Cyclone vorticity separate the water and pulls colder water from the deep layers to the surface
- Slow moving cyclones (up to 8km/h)
Note that not all tropical cyclones cause upwelling. Tropical cyclones speed is 20 – 30 km/h
Upwelling related to topography
cause
- Islands, submerged ridges and mounts deflect Deepwater currents (small area & unsteady in time)
Upwelling related to topography
examples
- Galapagos island and the Seychelles
Upwelling at the equator
Cause:
Upwelling at the equator
Effect:
- Divergence drags up nutrient rich water from bellow
examples of presence of equatorial upwelling
- Pacific
- Atlantic
absence of equatorial upwelling
- In Indian ocean due to
- Trade winds differ in seasons
- Absence of equatorward eastern boundary current that feeds into the equatorial current
