9.6-9.8

9.6 El Nino and la Nina

El Nino- Souther Oscillation (ENSO)

• when Peruvian waters, which usually is very productive with cold waters, is replaced with warm waters low in nutrients (less fish pop) and get lots of rain

• occurs in northern winter

• caused by the changing atmospheric conditions that lead to the ocean warming

• in this event, the high pressure systems in easter pacific declines and alows warm surface water to flow east towards Peru

• low pressure also moves to SA and brings lots of precipitation

La nina

• unusually cold waters

• trade winds are strong and cause more upwelling, bring up cold waters

• cause colder and wetter conditions to US while south east gets less precipitation

9.7 Langmuir Circulation

• Langmuir cells are parallel corkscrews patterns of water under strong winds across the surface

• the rotation of cells are perpendicular to the wind

• divergent zones cause downwelling and convergent zones cause upwelling

  

9.8 Thermohaline Circulation

• currents under surface layers are driven by density

• move much slower than surface currents

• thermohaline circulation is the circulation of seawater density depending on temp and salinity

Increasing seawater density:

• cooling, evaporating, and ice

Decreasing water density:

• precipitation, heating, ice melting, and freshwater runoff

Water mass

• V of seawater with a specific density because of the unique profile of temp and salinity

• once dense water sinks, it likely won’t change properties

Types of Water masses

• Antarctic Bottom Water (AABW) densest deep water

• North Atlantic Deep water (NADW)

Ocean Conveyor Belt

• helps transfer O2 and nutrients to deep water habitats