Sea Ice

Question 1

Describe the process of the freezing of seawater

Answer 1

1. It is a function of the water density, which is controlled by salinity
2. The more saline the lower the freezing point
3. As temperature decreases, density increases meaning you get very cold dense water trying to come to the surface, this is unstable!
4. The temperature of seawater decreases until it freezes, unlike freshwater
5. As the water freezes, salt is released into the surrounding water, increasing its salinity and density, it starts to sink and is unstable in the vertical

Question 2

How does convection influence the freezing of seawater?

Answer 2

The temperature of maximum density is well below freezing, which impacts the vertical convection and ocean circulation.
This convection may delay the onset of freezing and leave some parts of the sub-Arctic oceans ice free.

Question 3

What are specules?

Answer 3

Maximum of 2.5cm - Frazil Ice

Question 4

What is a Granular ice structure?

Answer 4

Ice that freezes quickly

Question 5

What is a Columnar ice structure?

Answer 5

Slow forming ice

Question 6

What is Grease Ice?

Answer 6

New Ice!
Lots of pieces of Frazil Ice
The sea appears oily and waves aren’t breaking like they normally do

Question 7

What the are the 3 types of ice sheet?

Answer 7

1. Ice Rind
2. Nilas
3. Brine Pockets

Question 8

What is first year ice?

Answer 8

Wind acts on ice to break it up. The ice recombines in a random way in response to the wind field. This is first year ice

Question 9

What size does ice grow to?

Answer 9

7-120cm and then up to 2m by the end of Year 1

Question 10

What are the other two types of ice with regards to time?

Answer 10

1. 2nd year ice, which lasts the summer

2. Multi-year ice

Question 11

What the 5 contributors to ice growth?

Answer 11

1. Freezing from above/below
2. Coalesence
3. Winter snowfall
4. Freezing of waterlogged snow
5. Freezing of supercooled water at the base

Question 12

Name 5 Ice Features

Answer 12

1. Ice Foot
2. Floe
3. Pressure Ridge
4. Keel
5. Rafting

Question 13

What are pressure hummocks?

Answer 13

Result of pressure creating landforms on ice

Question 14

What time of year is best for monitoring sea ice extents?

Answer 14

March

Question 15

What is happening in the Antarctic with regard to sea ice extent?

Answer 15

Some areas are increasing (North) but others are decreasing (South and West). This links to ocean circulation.

Question 16

When was the record minimum for Arctic sea Ice Extent?

Answer 16

Sept. 2012

Question 17

Which year had the largest Sept. minimum since 2006?

Answer 17

2013

Question 18

List 5 issues associated with sea ice

Answer 18

1. Extent = new transport routes
2. Passenger ships become ice bound
3. Pollution as a result of ships in areas that are protected
4. Geopolitical issues in the Arctic (Russian Flag)
5. Arctic sea ice extent may impact atmospheric circulation