ATMS 111 EXAM 2 GUIDE WITH
COMPLETE SOLUTION
Measuring sea level - ANSWER - Tide gauges are measuring sticks or floats in
wells: put a stick in the water with cm measurements and see where the
water hits.
- Always coastal.
- Few long records.
satellites - ANSWER TOPEX-Poseidon Radar Altimetry:
1992-2006 (with successors still going).
Instrument emits a short radar flash and measures the time of flight of its
reflection from earth. 1.000 times per second.
Measures sea level and ice sheet height.
Grace:
Launched in 2002
Twin spacecraft fly about 140 miles apart around the earth
Maps the earth's gravity field using GPS and microwave ranging system
Measures sea level, changes to ocean currents, water storage on land masses,
ice sheet mass balance, variations of mass within Earth
Sea level observations since 1880 - ANSWER Sea level rise since 1880 has
been 22 cm.
,Error was larger back in time because there were fewer measurements.
Sea level observations since 1993 - ANSWER This is satellite data and because
of that it is very accurate and has basically no error.
Most accurate satellite measurements: 9cm rise in last 25 years.
Most of the sea level drop was related to the mass transport of water from
the ocean to the continents.
It dipped in 2010-2011 because of strong La Nina event. A lot of water was
stored in inland areas. After this event it went back to normal.
What doesn't contribute to sea level rise? - ANSWER Sea ice
Ice shelves (these are connected to ice sheets but floating on ocean)
What contributes only a little bit to sea level rise? - ANSWER Permafrost
Snow cover
What factors do contribute to sea level rise? - ANSWER Thermal expansion of
sea water
Water expands when it warms, molecules are more excited and take up more
space.
This is the main contributor to sea level rise so far
Mountain glaciers
Ice sheets (greenland and antarctica)
Ice contributions to sea level rise - ANSWER The current contribution from
mountain glaciers is roughly on par with the ice sheets, though the rate of ice
sheet melt is quickly increasing
,Recent paper estimates average global contribution of 1.85 mm/year from
ice.
What influences sea level rise? Thermal expansion - ANSWER The ocean gains
heat from sunlight and greenhouse gases (including water vapor).
The heat in the ocean is moved from one place to another - either on the
surface, or moving from the surface to deeper parts of the water column.
The ocean also loses/gives off heat - melting ice, evaporating, or directly
heating the atmosphere.
If the ocean absorbs more heat than it releases, its heat content increases.
A warmer ocean takes up more space - leading to sea level rise.
Is the ocean heating up? yes. - ANSWER Thermal expansion is primary
contribution so far to sea level rise (60%).
Due to ocean heat content increases.
Water expands as it warms.
Ocean heat content has been steadily increasing in recent decades.
Monitoring thee ocean heat content.
Argo floats: - ANSWER Argo flats, since 2000 measure to 200 m depth.
Measure how hot the ocean is.
Are put into the ocean, where they float around. Every couple of days they
collect temperatures of all of the layers of the ocean.
Gives info about how warm and how salty the ocean water is.
, Why is't sea level rise uniform? glacial adjustment - ANSWER Glacial
adjustment:
Loading of the solid earth with ice.
Solid Earth subsidence due to ice loading. The ice sheet is heavy and creates a
depression on the ground, and the bulges on the side are taller. If we melt
the ice, the depression comes back up and the bulges go back down.
Depending on whether the place had an ice sheet on top of it or not, it might
still be bouncing back up.
Loading of the solid earth with ice, then the subsequent loss of ice (Glacial
Isostatic Adjustment)
Why isn't sea level rise uniform? Gravity and glaciers - ANSWER Ice sheets
attract water because of their gravitational pull. All else being equal, water
levels will always be a little higher closer to the ice sheet.
As their mass decreases, they have less gravitational pull. This makes water
flow away.
Local sea level goes down.
Higher than average rise on other side of the earth, because less gravitational
pull is releasing water from a specific place.
If Greenland and Antarctica melted, it would have a small local reduction in
sea level, but far away from Greenland and Antarctica there would be a huge
sea level rise.
Why isn't sea level rise uniform?
additional reasons - ANSWER - Glacial isostatic adjustment
COMPLETE SOLUTION
Measuring sea level - ANSWER - Tide gauges are measuring sticks or floats in
wells: put a stick in the water with cm measurements and see where the
water hits.
- Always coastal.
- Few long records.
satellites - ANSWER TOPEX-Poseidon Radar Altimetry:
1992-2006 (with successors still going).
Instrument emits a short radar flash and measures the time of flight of its
reflection from earth. 1.000 times per second.
Measures sea level and ice sheet height.
Grace:
Launched in 2002
Twin spacecraft fly about 140 miles apart around the earth
Maps the earth's gravity field using GPS and microwave ranging system
Measures sea level, changes to ocean currents, water storage on land masses,
ice sheet mass balance, variations of mass within Earth
Sea level observations since 1880 - ANSWER Sea level rise since 1880 has
been 22 cm.
,Error was larger back in time because there were fewer measurements.
Sea level observations since 1993 - ANSWER This is satellite data and because
of that it is very accurate and has basically no error.
Most accurate satellite measurements: 9cm rise in last 25 years.
Most of the sea level drop was related to the mass transport of water from
the ocean to the continents.
It dipped in 2010-2011 because of strong La Nina event. A lot of water was
stored in inland areas. After this event it went back to normal.
What doesn't contribute to sea level rise? - ANSWER Sea ice
Ice shelves (these are connected to ice sheets but floating on ocean)
What contributes only a little bit to sea level rise? - ANSWER Permafrost
Snow cover
What factors do contribute to sea level rise? - ANSWER Thermal expansion of
sea water
Water expands when it warms, molecules are more excited and take up more
space.
This is the main contributor to sea level rise so far
Mountain glaciers
Ice sheets (greenland and antarctica)
Ice contributions to sea level rise - ANSWER The current contribution from
mountain glaciers is roughly on par with the ice sheets, though the rate of ice
sheet melt is quickly increasing
,Recent paper estimates average global contribution of 1.85 mm/year from
ice.
What influences sea level rise? Thermal expansion - ANSWER The ocean gains
heat from sunlight and greenhouse gases (including water vapor).
The heat in the ocean is moved from one place to another - either on the
surface, or moving from the surface to deeper parts of the water column.
The ocean also loses/gives off heat - melting ice, evaporating, or directly
heating the atmosphere.
If the ocean absorbs more heat than it releases, its heat content increases.
A warmer ocean takes up more space - leading to sea level rise.
Is the ocean heating up? yes. - ANSWER Thermal expansion is primary
contribution so far to sea level rise (60%).
Due to ocean heat content increases.
Water expands as it warms.
Ocean heat content has been steadily increasing in recent decades.
Monitoring thee ocean heat content.
Argo floats: - ANSWER Argo flats, since 2000 measure to 200 m depth.
Measure how hot the ocean is.
Are put into the ocean, where they float around. Every couple of days they
collect temperatures of all of the layers of the ocean.
Gives info about how warm and how salty the ocean water is.
, Why is't sea level rise uniform? glacial adjustment - ANSWER Glacial
adjustment:
Loading of the solid earth with ice.
Solid Earth subsidence due to ice loading. The ice sheet is heavy and creates a
depression on the ground, and the bulges on the side are taller. If we melt
the ice, the depression comes back up and the bulges go back down.
Depending on whether the place had an ice sheet on top of it or not, it might
still be bouncing back up.
Loading of the solid earth with ice, then the subsequent loss of ice (Glacial
Isostatic Adjustment)
Why isn't sea level rise uniform? Gravity and glaciers - ANSWER Ice sheets
attract water because of their gravitational pull. All else being equal, water
levels will always be a little higher closer to the ice sheet.
As their mass decreases, they have less gravitational pull. This makes water
flow away.
Local sea level goes down.
Higher than average rise on other side of the earth, because less gravitational
pull is releasing water from a specific place.
If Greenland and Antarctica melted, it would have a small local reduction in
sea level, but far away from Greenland and Antarctica there would be a huge
sea level rise.
Why isn't sea level rise uniform?
additional reasons - ANSWER - Glacial isostatic adjustment
