Transcript Change Indicators in the Upper Atmosphere

CLIMATE CHANGE INDICATORS:
UPPER ATMOSPHERE
Changes occurring in the
Lower Atmosphere (Troposphere)
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Global Temperatures
GHG emissions
Heat waves
Drought
Precipitation
Flooding
Cyclones
Sea Surface Temp
Sea level
Ocean acidification
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Arctic sea ice
Glaciers
Lake ice
Snow cover
Snowpack
Growing season
Plant hardiness
Leaf/Bloom dates
Bird wintering ranges
It’s easy to notice or hear about change
when it’s happening around you (in the
troposphere)
What about the other layers of the
atmosphere? Are changes occurring there?
How is the upper atmosphere measured
from the ground?
Incoherent Scatter Radar
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RADAR (RAdio Detection And Ranging) is a technique for detecting and
studying remote targets by transmitting a radio wave in the direction of the
target and observing the reflection of the wave
Target of incoherent scatter radar is electrons in the earth's ionosphere
rather than a discrete hard target (like an airplane)
High energy ultraviolet radiation from the sun removes electrons from some
of the atoms and molecules in this region, and these electrons can scatter
radio waves
Amount of energy scattered from each electron is well known, the strength
of the echo received from the ionosphere measures the number of electrons
in the scattering volume
Scattering technique can determine density, temperature, velocity, and
composition of the charged upper atmosphere [ionosphere]
2000
MIT Haystack
Where are Incoherent Scatter Radars?
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This map shows all of the world's operational incoherent
scatter radars
There are only 9 worldwide (as of 2000)
Millstone Hill
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Located in Westford, MA
Capable of making observations
ranging from 90 to 1000 km in
altitude
Radar system
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MIT Haystack
A fixed vertically pointing antenna
(Zenith) uses megawatt transmitter
and 68 m diameter fixed antenna
[1963 - now]
A fully steerable antenna (MISA),
46 meter diameter [1978 – now]
SWFX 5
EISCAT/ESR
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European Incoherent
Scatter Scientific
Association
It operates three
incoherent scatter
radar systems
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Wikipedia | Credit Tom Grydeland
Two in Northern Scandinavia
One in Svalbard
Arecibo
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Radio Telescope
located in Puerto Rico
305 m in diameter
(largest single-aperture telescope)
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Makes frequent
appearances in movies
and TV shows
NOAA accessed via Wikipedia
Jicamarca Radio Observatory (JRO)
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Studies the equatorial
ionosphere in Lima,
Peru
Main antenna is the
largest of all the
incoherent scatter
radars in the world
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Wikipedia | Public Domain
300m x 300m square array
NASA Upper Atmosphere Satellite Projects
The Mission
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TIMED - Thermosphere,
Ionosphere, Mesosphere,
Energetics and Dynamics
The Instrument
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Developed to explore Earth’s
atmosphere above 60 km
Launched December 2001
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SABER - Sounding of the
Atmosphere using Broadband
Emission Radiometry
Aboard TIMED
Designed to measure energy
budget of the mesosphere
and lower thermosphere
Collected data over 8 years
Cutting Edge Research …
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~40 years (1968 – 2006) of ionospheric data
taken from the Millstone Hill Incoherent Scatter
Radar is used
MIT scientists have been studying, analyzing and
interpreting the results
Here is what they have discovered …
What trend do you notice?
Zhang, Shun-Rong | MIT Haystack
MIT Scientists state a +1.9K/year
Zhang, Shun-Rong | MIT Haystack
What trend do you notice?
Zhang, Shun-Rong | MIT Haystack
MIT Scientists state a -1.2 K/year
Zhang, Shun-Rong | MIT Haystack
What trend do you notice?
Zhang, Shun-Rong | MIT Haystac
MIT Scientists state a -3.2 K/year
Zhang, Shun-Rong | MIT Haystack
Zhang, Shun-Rong | MIT Haystack
Altitude vs.
Ion Temperature % change per decade
There is more error in
the lower atmosphere
because there are
fewer measurements
made
The temperature
profile indicates a
DECREASE in ion
temperature in the
upper atmosphere
above 200km
Zhang, Shun-Rong | MIT Haystack
Let’s Compare
LOWER ATMOSPHERE
Things are heating up …
 Average global
temperature has
increased at a rate of
roughly 0.15 - 0.20°C
per decade over the
past 40 years
 This seems small, but has
triggered many changes
(polar cap melting, etc.)
UPPER ATMOSPHERE
Things are cooling down …
 Trend shows a 2 - 3˚C
decrease per decade over
the past 40 years
 Change is much bigger
(10X!) than in the lower
atmosphere
 Total change is readily
observable in data record
What is causing the Upper Atmosphere to cool?
The answer is Radiative Cooling
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Process by which a body loses
heat by radiation
Greenhouse gases
(particularly CO2) radiative
effects become more
pronounced and produce a
cooling effect in the upper
atmosphere
Lastovicka et al. “Global Change in the Upper Atmosphere.” Science v.314 no.5803 (24 November 2006) pg. 1253 – 1254.
A quick video may help
Active and Ongoing Research
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The upper atmosphere
is an area that requires
further studied
More data is needed
to confirm the
observed trends
Observed change in
upper atmospheric
temperature is large,
which makes it easier
to measure
Photo taken by Shun – Rong Zhang | used with permission