3: Fresh water

Question 1

Name the different sinks for freshwater (for the Arctic Ocean)

Answer 1

1. Ice export through the Fram Strait
2. Water export through the Canadian archipelago
3. water export through Fram Strait

Question 2

Name the different sources of freshwater (for the Arctic Ocean)

Answer 2

1. Runoff from rivers. The three biggest rivers comes off the russian side.
2. Low salinity water from the Pacific Ocean through the Bering Strait.
3. Precitipitation minus evaporation

Question 3

What is the upper layer of the Arctic Ocean?

Answer 3

The polar mixed layer. This is low salinity water.

Question 4

Where is the ocean temperature stratified, and where is it salinity stratified? How does this affect the depth of the mixed layer?

Answer 4

The temperate regions of the world ocean are temperature stratified, so the thermohaline is defining the bottom of the mixed layer.
The polar oceans are salinity stratified, and thus the halocline is defining the bottom of the mixed layer.

Question 5

How deep is the convection layer in the Arctic Ocean?

Answer 5

Less than 70m in the Arctic.

Question 6

Describe the seasonal imput of fresh water from rivers.

Answer 6

The fresh water imput from the biggest rivers starts in april, has a peak in june, ant stops the input in november, (see figure)

Question 7

which natural tracers (6) can be used to track how water masses move around in the ocean?

Answer 7

Most used: temperature and salinity, as well as oxygen,
Also nutrients like:
- Nitrate (NO3)
- phosphate (PO4)
- Silicate (Si).
All these tracers may have sources and sinks in the water mainly because of biological activity,
Si can be a useful tracer for studies in the Arctic Ocean.
Falck used a N-P relationship to identify the amount of Pacific water in the (eastern) Fram Strait. (Which showed that approx 90% of the upper water in the Fram Strait stemmed from Bering Strait –> but this changes from year to year)
Another natural tracer: δ^18 O useful in the polar regions.

Question 8

which anthropogenic tracers (6) can be used to track how water masses move around in the ocean?

Answer 8

• Tritium (3^H) from nuclear bomb tests
• Chlor-Fluor-Carbons (CFC-11 and CFC-12) from cooling liquid in refrigerators
• Since we know the time these tracers where used, we can know when the water was last in contact with the atmosphere.