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Climate
Role |
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Surface
Energy Balance |
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Surface
Water Balance |
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Vegetation (Canopy) |
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Soil
(moisture) |
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greenhouse
gas emissions |
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è affects
global energy and biogeochemical cycles |
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creation
of aerosols |
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è affects
global energy and water cycles |
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surface
reflectivity (albedo) |
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è affects
global energy cycle |
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impacts
on surface hydrology |
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è affect
global water cycle |
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The potential evaporation is defined as the
maximum possible evapotranspiration for the prevailing atmospheric
condition. |
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PE is the amount of moisture the atmosphere
demands based upon its energy status. |
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If there is a higher energy level in the
atmosphere, e.g. very high temperature due to intense solar radiation, it
demands more moisture from the Earth’s surface. |
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If PE > available evapotranspiration è leads to
dry surface |
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PE < available evapotranspiration è leads to runoff. |
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Climate interacts only with water that is on the
surface or in the soil water zone. |
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The soil water zone extends downward to the
depth penetrated by the root of the vegetation. |
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Soil storage capacity (field capacity of the soil) is the amount of moisture the
soil can hold. |
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If soil water content increases above the
capacity, gravitational forces carry the water downward to the water table,
where it becomes groundwater. |
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Vegetation Properties |
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Type and density |
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Soil Properties |
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Depth and physical properties |
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(e.g., moisture) |
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Typical Height |
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Leaf Area Index (LAI) |
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Leaf
area index (LAI) is ratio of the total area of all leaves (one-side) on a
plant to the area of ground covered by the plant. |
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It
defines the area that interacts with solar radiation and that is
responsible for carbon absorption and exchange with the atmosphere. |
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Canopy – The collection of vegetable matter
covering the land surface is called the plant canopy. |
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Over moist regions, most of the water
transferred from soil to atmosphere moves through vegetation. |
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Water moves into the roots, through the plant
parts to leaves, and passes into the atmosphere through stomata. |
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Root and stomata control the exchanges between
the vegetations and the atmosphere. |
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The idealized canopy is used to quantify the
vegetation-atmosphere fluxes via LAI and leave and atmosphere properties. |
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Surface ice of any depth is a much more
effective reflector of solar radiation than the underlying surface. |
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Sea ice is a good insulator and allows air
temperature to be very different from that of the seawater under the ice. |
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At present, year-round ice covers 11% of the
land area and 7% of the world ocean. |
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One
major climate effect of sea ice is to seal off the underlying ocean from
interaction with the atmosphere. |
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Without
an sea ice cover, high-latitude oceans transfers large amount of heat to
the atmosphere, especially in winter. |
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With an
sea ice cover, the heat flux into the atmosphere is stopped. In addition,
the ice surface absorbs little incoming solar radiation. Winter air
temperature can cool 30°C or more near a sea-ice cover. |
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The Antarctic Ice Sheet holds the equivalent in
seawater of 66 meters of global sea level. |
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The Greenland Ice Sheet holds the equivalent of
6 meters of global seawater. |
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