Sea ice

Question 1

Cryosphere

Answer 1

portions of Earth’s surface where water is sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, frozen ground

Question 2

Brine and brine rejection

Answer 2

Brine - droplets of highly saline water formed due to salt accumulation in small pockets as ice crystals form
brine rejection - brine expelled back into ocean, increases salinity and density of near-surface water brine drains out to sea so ice salinity decreases

Question 3

Frazil

Answer 3

small needle-like crystals, 3-4mm diameter, suspended in water - develop into smooth ice sheets in calm ocean water and slushy circular disks aka pancakes in rough ocean water

Question 4

Interactions between sea ice sheets

Answer 4

rafting - thin ice sheets pushed by wind or currents to slide over each other
ridging - sea ice pushed around into piles that rise and form small mountains above sea level surface

Question 5

Classification of sea ice

Answer 5

new ice - less than 10 cm
young ice - 10-30 cm
first-year ice - thicker than 30 cm, has not survived summer melt
multiyear ice - survived melt, 2-4 m

Question 6

Leads

Answer 6

long, linear areas of open water ranging from a few meters to over a kilometer in width, and tens of kms long
develops as ice diverges
absorb solar energy leading to melting of surrounding ice
important for wildlife

Question 7

polynyas

Answer 7

irregularly-shaped areas of persistent open water
absorb solar energy leading to melting of surrounding ice
important for wildlife

Question 8

melt ponds

Answer 8

pools of melted snow and ice on sea ice surface created during summer melt
absorb solar energy leading to melting of surrounding ice

Question 9

albedo and ice albedo feedback

Answer 9

see diagram

Question 10

fast ice

Answer 10

sea ice that is anchored to shore or ocean bottom

Question 11

principal forces acting on ice

Answer 11

wind
ocean currents - drag to wind-driven motion
coriolis force - deflects ice motion to right of left due to Earth’s rotation
internal ice stress - resistance to wind-driven motion, responsible for ice deformation
sea surface tils - the tilt of the surface of the ocean

Question 12

Arctic dynamics

Answer 12

sea ice trapped in the Beaufort Gyre may circulate around Arctic for several years
sea ice trapped in the Transpolar Drift Stream leaves 1-2 years

Question 13

Antarctic dynamics

Answer 13

Sea ice gradually moves to northern ice edge after it forms

sea ice circulation is generally in a clockwise direction around Antarctica

Question 14

Role of sea ice in climate

Answer 14

global mean temp - high albedo keeps surface cooler
ocean circulation - dense waters form in sea ice regions and influence the ocean circ
gas exchange - sea ice acts as a lid to prevent gas exchange
Does NOT affect sea level

Question 15

Remote sensing and satellite observations

Answer 15

satellites provide continuous, nearly complete record of sea ice cover (since 1979)
observe microwaves emitted by sea ice surface
pixels are 25kmx25km
criterion >15% (conc)
sea ice extent - 1 or 0
sea ice extent area - sum (extent*area)
satellite sensors also use visible light, infrared, and radar to detect sea ice - good density of observations
submarine observations - measure sea ice draft (profiles of the bottom of the ice relative to sea level) which allows for inferences about thickness

Question 16

Arctic vs Antarctic

Answer 16

see diagram on desktop, google docs