Download ppt for Collow

Remote Sensing of the Oceans and
Atmosphere
Tom Collow
December 10, 2009
Aura was launched on July 15, 2004 from
Vandenburg Air Force Base, California.
Aura is the last satellite in line on the A-train.
“The Aura Mission studies the Earth’s ozone, air quality, and climate. It
conducts research on the composition, chemistry, and dynamics of the
Earth’s atmosphere.”
More Facts
•
•
•
•
Sun-synchronous polar orbit
98° inclination (retrograde orbit)
Altitude is 705 km
Design life is 5 years with an operational goal
of 6 years
• Remember, it was launched in 2004 so the
satellite is probably nearing the end of its
usage
• The Aura satellite uses four different
instruments to collect data.
• HIRDLS – High Resolution Dynamics Limb
Sounder
• MLS – Microwave Limb Sounder
• OMI – Ozone Monitoring Instrument
• TES – Tropospheric Emission Spectrometer
• Is the ozone layer recovering as expected?
• What are the sources and processes that
control atmospheric pollutants?
• What is the quantitative impact of these
constituents on climate change?
Ozone hole progress,
September 16, 2009
•
•
•
•
Limb infrared filter radiometer
21 channels ranging from 6.2 to 17.76μm.
Vertical resolution of 1.2 km.
A good vertical resolution is important because most physical
processes of interest to Aura occur on short vertical scales
( < 5 km.)
• Measures variables in the upper troposphere, stratosphere,
and mesosphere
• A blockage on the instrument caused the aperture to only be
able to see 20% of the Earth’s surface. Attempts to remove
the blockage have failed but even so, the instrument can still
make measurements at a high vertical resolution.
How it Works
• First, radiance calibration is done by having the instrument
view cold space ( just above the limb of the atmosphere) and
then an internal blackbody target of known temperature.
• Four channels measure the emission of CO2 which has a
known mixing ratio.
• Using that data, transmittance is then calculated.
• The equation of radiative transfer is inverted to determine the
vertical distribution of the Plank-black-body function from
which temperature is a function of pressure.
• Using the temperature profile, the Planck function profiles of
the other constituents can be obtained.
• These profiles are then used to calculate the transmittance of
these compounds as well as the corresponding mixing ratios.
What does it Measure?
•
•
•
•
•
•
•
•
•
•
•
•
O3
H2O
CH4
N2O
NO2
N2O
HNO3
N2O5
CFC11
CFC12
CIONO2
Aerosols
It can also determine the
locations of cloud tops, subvisible cirrus clouds, and
polar stratospheric clouds
using the H2O data.
Sub-visible cirrus over eastern Africa and Saudi Arabia.
HIRDLS measurement of
temperature over the
Northern Hemisphere
Source:
http://www.eos.ucar.edu/hirdls/science/gallery/HirdlsTe
mp20050129.jpg
Mountain Waves as seen through
temperature fluctuations
Mountain waves reaching the mesosphere have been theorized but
this is the first time they are actually being observed
Source: http://aura.gsfc.nasa.gov/science/feature-030907.html
Microwave Limb Sounder
• Five frequency bands ranging from 118 GHz to 2500 GHz (1
GHz = 1,000,000,000 s-1)
• 1.5 – 3.0 km. vertical resolution
• Measures atmospheric composition, temperature, humidity,
and cloud ice in the upper troposphere, stratosphere, and
mesosphere.
• Unlike the HIRDLS which can “see” clouds, the MLS can “see”
cloud ice.
• The data is used to track the stability of the stratospheric
ozone layer, help improve predictions of climate change and
variability, and help improve understanding of global air
quality.
Variables Measured
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
H2O
O3
CIO
BrO
HCl
OH
HNO2
HNO3
HCN
N2O
CO
HOCl
CH3CN
Cloud Ice
Temperature
ClO (chlorine monoxide) is the primary form of chlorine that
destroys ozone.
BrO (bromine monoxide) is the primary form of bromine that
destroys ozone. It is also the primary form of bromine in the
stratosphere.
Measurements of H2O (water vapor) and cloud ice allows for a
better understanding of climate change.
H2O, HNO3 (nitric acid), and temperature provide information on
processes that can lead to ozone loss in the antarctic and arctic.
Measurements in the upper troposphere of O3 and CO are
important for air quality research as these pollutants can be
transported upwards from the boundary layer by convective
processes and then transported great distances due to stronger
winds there.
The upper troposphere is highly significant in the transport of
pollutants from Asia to North America.
2006 Antarctic ozone hole as seen by the Microwave Limb Sounder.
Source: http://aura.gsfc.nasa.gov/science/feature-022207.html
Cloud ice measured by MLS (upper left) and compared to computer model
simulations. There is a noticeable discrepancy over South America between the
observation and the models.
Source: http://aura.gsfc.nasa.gov/science/top10_cloudice.html
References
•
•
•
•
•
•
•
•
Goddard Space Flight Center. (2009). Aura atmospheric chemistry. Retrieved from
http://aura.gsfc.nasa.gov/index.html
Goddard Space Flight Center. (2007). ‘Double record breaker’ 2006 anarctic ozone hole seen
by MLS. Retrieved from http://aura.gsfc.nasa.gov/science/feature-022207.html
Goddard Space Flight Center. (2006). First global measurement of cloud ice in upper
troposphere. Retrieved from http://aura.gsfc.nasa.gov/science/top10_cloudice.html
Goddard Space Flight Center. (2007). Spectacular mountain wave events observed by HIRDLS.
Retrieved from http://aura.gsfc.nasa.gov/science/feature-030907.html
Jet Propulsion Laboratory. (2009). Microwave limb sounder. Retrieved from
http://mls.jpl.nasa.gov/
NASA. (2009). Aura understanding and protecting the air we breathe. Retrieved from
http://www.nasa.gov/mission_pages/aura/main/index.html
Schoeberl, M.R., Douglass, A.R., Hilsenrath, E., Bhartia, P.K., Barnett, J., Gille, J, Beer, R.,
Gunson, M., Waters, J., Levelt P.F., & DeCola, P. (2004). Earth observing systems
missions benefit atmospheric research [Electronic version]. EOS, Transactions,
American Geophysical Union, 85(18), 177-184.
UCAR. (2008). High resolution dynamics limb sounder. Retrieved from
http://www.eos.ucar.edu/hirdls/