Unit 4 Notes from Readings

Unit 4 Notes from Readings - Notes from Readings Deep-sea...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Notes from Readings Deep-sea Circulation - on average, the ocean is about 4km deep - Near the surface and in the mixed layer, oceanographers use drifters and stationary current meters to measure flow in the slow flow. - Below the slow flow, they use sea surface height, gravity, and pressure differences to calculate flow. - Water motion in the deep sea is slow, driven by gravity and caused by changes in the density of sea water. - For the most part, it is at the surface, the interface between air and sea, that temperature or salinity change. - An increase in salinity can occur with evaporation or the formation of sea ice. - If the density increase due to these processes is sufficient, ocean water will slowly sink and flow downward until it reaches a level of equal density or the seafloor. - Almost all of the ocean’s deep water forms through the effects of cooling and freezing at high latitudes. - Area that generates the most bottom water lies just south of Greenland in the North Atlantic – NADW - Near the Antarctic, NADW mixes with water flowing around Antarctica and then moves into the Pacific and Indian Oceans - The very densest water forms during the southern winter beneath the Antarctic ice shelf – very cold and salty, flows northward. - Antarctic Bottom Water generally stays in the Atlantic Ocean because ridges on the seafloor block its path. - One of the most common ways to sample water in the deep sea is to use a specially designed collecting device called a Niskin Bottle. o An ingenious and inexpensive piece of equipment, but getting it into deep sea is costly. o Made out of thick gray PVC tubing, is attached to a cable, directly or a part of a larger sampling unit, and lowered in to the sea. o Subsequent chemical analyses identify the different water masses present throughout the water column. - in between the surface and deep waters of the sea lies the intermediate ocean - in the Mediterranean Sea intense evaporation creates a very salt, warm intermediate water mass that flows out through the Straits of Gibraltar, beneath less salty, incoming surface water. - Even though it is warm, the Mediterranean water is so salty that when it enters the North Atlantic it spills downward to a depth of a bout 1000 meters, where cold water is of an equal density. - Mediterranean intermediate water forms a salty liquid avalanche spreading down and out. - Mediterranean intermediate water flowing within the North Atlantic meanders and creates eddies. - To precisely measure the sea’s flow in the horizontal as well as vertical direction, use sound waves via shipboard and stationary instruments called acoustic Doppler current meters. - To track flow at depth, use specially designed drifters called Argo. -
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/27/2010 for the course OCEAN 102 taught by Professor Strickland during the Winter '08 term at University of Washington.

Page1 / 6

Unit 4 Notes from Readings - Notes from Readings Deep-sea...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online