Lecture 16 - Ocean Circulation and Major Ocean Currents -PHYS OCE

characteristics of pacific ocean

largest ocean in area and volume, less saline than ATL, widest near equator

why is it important to note that the pacific ocean is the widest at the equator

there are important equatorial dynamics caused by this including El Nino

where does pacific connect to indian ocean

indonesian throughflow

where does the pacific connect to the arctic ocean

bering sea and bering strait

western boundary current in pacific ocean

kuroshio

what are the semi enclosed seas along the asian continents in the pacific

sea of japan, yellow sea, east china sea, south china sea

difference between kuroshio in pacific and gulf stream in ATL

kuroshio has a bi modal path due to presence of emperor seamounts, no barrier in ATL

what happens when kuroshio separates from the coast

When the warm Kuroshio Current collides with the cold Oyashio Current off the eastern coast of Japan, the Kuroshio separates from the coastline—turning eastward into the open Pacific Ocean—forming a region known as the Kuroshio Extension

what happens at the equator in pacific currents

coriolis is 0 and the only transport is in the direction of the wind

what are the equatorial currents driven by in the PAC

trade winds, E to W winds pile warm water in west until a balance is established between pressure gradient and wind stress

what happens when wind piles warm water in western pacific from E to W

raises sea level and deepens thermocline

equatorial undercurrent

moves west to east, stabilized by coriolis forces N and S of equator

characteristics of equatorial undercurrent

300km wide 200m deep U = 1.5m/s

EBCs in PAC

energy in eddies as large as mean energy flow, equator ward upper flow and poleward undercurrent, coastal upwelling for biological production

what two main sites of upwelling in PAC

peru and california

what does coastal upwelling depend on

topography of shelf and continental slope

important phenomenon of equatorial pacific

El Nino Southern Oscillation (ENSO)

what does ENSO do

causes considerable damage worldwide from interactions of ocean-atmosphere

what is ENSO an example of

coupled air-sea interaction process that involves feedback between ocean and atmosphere

steps in atmosphere-ocean interaction from ENSO

1. atmospheric conditions change caused by wind

2. oceanic conditions change caused by currents

3. temperature change of ocean

4. atmosphere changes from caused by air temp, wind, rain

5. all of these flow into air-sea heat exchange

one of the biggest el nino years

2015

what year did la nina happen

2021

what can observations of equatorial temperatures in PAC tell us

too cold = la nina, too warm = el nino

what is el nino driven by

changes in wind pattern over the equatorial pacific, wind is not as strong in east and more of the warm water from the west comes to the east = more wet warm area further east towards california

upwelling in normal, la nina, el nino

normal = upwelling on east, la nina = strong upwelling, el nino = none

thermocline normal, la nina, el nino

wind normal = brings up thermocline on east, la nina = strong thermocline, el nino = none

what is la nina driven by

changes in wind pattern over the equatorial pacific, wind is strong in east and less of the warm water from the west comes to the east = less wet cold area further east towards california

what were the effects of el nino in peru

caused weakened upwelling so it impacted fishing industry

jet stream in PAC

fast-flowing ribbon of upper-level westerly wind (located roughly 30,000 feet up) that acts as a primary conveyor belt steering storms and moisture across the Pacific Ocean toward North America

el nino impact on jet stream in atl

shifts south into hurricane path = not allowing intense hurricanes

la nina impact on jet stream in atl

shifts south = more storms