General:

Cryosphere: anywhere where water is in a frozen state - Snow, Glaciers, ice sheets and shelves.

Seasonally frozen ground = frozen for 2 weeks or more.
As a zonal phenomenon (across latitudes) from pole to equator it is defined as continuous (80-90%), discontinuous(50-90%), Sporadic(10-50%) and isolated(
In the Northern Hemisphere continuous permafrost boundary is approximatley at the MAAT isotherm of -8 degrees.
Laptev, East Siberia and the Beufort sea are home to sub-sea permafrost.
Relationship between air temp and ground temp can be described using a transfer function known as the n-factor.
n-factor = ratio of surface freezing/thawing index to the air freezing/thawing index. Approximatley 0.5 for moist and 1 for dry soils.
Snow/veg results in a steep temperature gradient whereas the gradient is lessened in high arctic, barren areas with thin/no snow cover.
Zero Curtian effect = when water -> ice latent heat is released prolonging a 0 degrees temperature. Conditions for ZCE: moisture in the active layer & soil isothermal near 0 degrees.
Zero annual amplitude occurs at a depth where surface temperature variation is not seen in the permafrost.
Difference between MAGST and TTOP is the thermal offset.
Frozen water expansion approx 9%.
Dissolved minerals (e.g. saline water) can have a depressed freezing point, and when soil exists unfrozen within permafrost due to a depressed freezing point it is called a cryopeg.
Freezing degree-day = negative difference between 0 and daily mean temp.
Thawing degree-day = positive difference between 0 and daily mean temp.
Seasonal and diurnal rhythms dampened with depth in PF.
Southern-most limit of permafrost FDD=TDD.

	Erstellt von samflint93 vor etwa 11 Jahre

University finals GEOG3004 (4 - micro permafrost) Notiz am Lecture 4 core, erstellt von samflint93 am 14/10/2013.

Lecture 4 core