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On 7 Jul 2005,
scientists were
able to perform the
first accurate sea-level
monitoring by satellite using
a number of different instruments
(such as the Gravity Recovery
and Climate Experiment - or
GRACE- satellite, above). Satellite
data was collected on changes
in Earth's gravitational field, the
mass of polar ice caps, and ocean
topography and circulation (inset).
Using this data, it was determined
that . in the last 50 years, the rate
at which the sea level is rising
is 1.8 mm per year - although in
the last 12 years, this rate has
increased to 3 mm per year.
-
The radiometric
temperature was
measured by the
amount of radiation
(or lack of it) from the
Antarctic Ridge.
The lowest
radiometric Earth
temperature recorded by
satellite is -93.2'C, on a high
ridge in Antarctica, as preliminarily
announced by NASA in Dec 2013.
Data was collected by satellites
including NASA's Terra (right) over
32 years and it was found that the
dry and clear air of the Antarctic
allows heat to be efficiently
radiated into space.
monitoring climate change was
launched on 2 Nov 2009 by the European
Space Agency (ESA). The Soil Moisture
and Ocean Salinity (SMOS) mission surveys
critical parts of the water cycle between
oceans, air and land by mapping the saltiness
of the sea and monitoring water content in the
planet's soil. The satellite works by measuring
Earth's natural microwave emissions, which
alter with the changing moisture levels on
land or the salinity of the sea.
The fastest-melting Antarctic
glacier is Pine Island Glacier, which
is dropping in height by up to 16 m
(52 ft) a year. scientists discovered.
Key data came from Autosub
(below), an autonomous submarine
which was sent under the vast
glacier to reveal it has become
detached from an undersea ridge,
allowing warm water to flow under
it and increase the rate of melt.
From its launch in 2009 until its
burn-up in 2013, ESA's Gravity
Field and Steady-State Ocean
Circulation Explorer (GOCE, above)
was the most accurate gravitymapping
satellite, working to
1 milliGal (a unit used to measure
the gravitational field).
The highest-resolution maps
of Earth's gravity field, however,
were created in 2013 by an Australian­
German team using data obtained
from the US Space Shuttle. The maps
(right) improved the resolution of
previous global gravity field maps by
a factor of 40, and revealed that the
pull of gravity is at its strongest at the
North Pole; the lowest is at the top of
the Huascaran mountain in the Andes.