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Average
temperature is around 28°C, rising in early summer up to
40°C. Valverde (1972) says the wet summer regime is due to penetration
of an equatorial continental air mass originated from Amazonia.
Climate in winter is dominated by the tropical-atlantic air mass
coming from brazilian highland. As Pantanal's amphitheater is open
to South, sometimes polar-antarctic atmospheric fronts advance
into the area and extremes of around 0°C may occur. These
are the friagens which can provoke frost-biting geadas
in the plants over large swamp areas.
Moisture
is usually around 70%, reaching over 80% during late summer
(Tarifa,1986). Concerning the ecological conditions of this immense
area, rainy season is concentrated from October to March,
when there is a rainfall of 1000-1400 mm (Dubs,1992), slightly
less than in central-brazilian cerrado, but the Paraguay
River and its tributaries swell and flood the low plain,
rising 2-3m (sometimes even 4m) deeper than in drought season..
Therefore Pantanal is a large climatic enclave in which the run-off
from the surrounding relatively wet highlands, carried by a series
of large rivers, succeeds a sustained wetland environment under
the conditions of a basically semi-arid climate.
From
a different point of view, Pantanal is probably the most important
window of freshwater evaporation on the globe.
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