Barry, R. and Gan, T.Y (2011) The Global Cryosphere; past, present and future, Cambridge University Press-Cambridge. (Chapters 1 and 5) Flashcards
Cryosphere is the term used to describe
the portion of the Earth’s surface where water is in its frozen state- snow cover, glaciers, ice sheets and shelves, freshwater ice etc etc.
The cryosphere has seasonally varying components and more permanent features.
Why is the cryosphere an integral part of the climate system?
Important linkages and feedbacks with the atmosphere and hydrosphere that are generated through its effects on surface energy and on moisture fluxes, by releasing large amounts of freshwater when melting occurs, e.g affecting thermohaline oceanic circulations
It affects atmospheric processes such as clouds and precipitation, and surface hydrology.
The greatest potential source of freshwater are
Ice sheets
Permafrost may occur where
the mean annual air temperature is less than -1oC and is generally continuous where it is less than -7oC.
The cryosphere plays several critical roles in the climate system…
Ice albedo feedback mechanism
Ice and snow cover increase albedo, thereby increasing the reflected solar radiation and lowering the temperature, thus enabling the ice and snow cover to increase further.
The cryosphere plays several critical roles in the climate system…
The insulation of the land surface by snow cover and of the oceans/lakes/rivers by floating
This insulation greatly modifies the temperature regime in the underlying land or water.
The cryosphere plays several critical roles in the climate system…
It’s effect on the hydrological cycle
Due to the storage of water in snow cover, glaciers, ice caps and ice sheets and associated delays in fresh water runoff.
The cryosphere plays several critical roles in the climate system…
The more permanent features of the cryosphere have a large influence on
…eustatic changes in global sea level.
The cryosphere plays several critical roles in the climate system…
Seasonally frozen ground
Seasonally frozen ground and permafrost modulating water and energy fluxes, and the exchange of carbon (eg Ch4), between the land and the atmosphere.
Permafrost is…
rock or sediment in which the the temperature remains below 0oC for two or more years.
Permafrost is distributed geographically as…
a series of bands that roughly conform with latitude- continuous or discontinuous.
The occurrence of frozen ground in the upper surface layer can be mapped using…
a variety of remote sensing techniques.
Thermal offset describes…
the fact the mean annual ground surface temperature generally exceeds the temperature at the top of the permafrost.
The active layer is…
the layer above the permafrost that is frozen in winter and thaws in the summer- it is a type of seasonally frozen ground and lies above the permafrost- the upper surface of the permafrost.
Active layer thickness is dependent on a number of factors
It decreases with increasing latitude due to the shorter thawing season
It decreases where there is a thick vegetation cover or snow pack.
The soil moisture content is another important variable that determines the heat capacity of the soil.
