Madhu Gyawali Advisor - Dr. Pat Arnott
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Transcript of Madhu Gyawali Advisor - Dr. Pat Arnott
Madhu GyawaliAdvisor - Dr. Pat Arnott
NASA-A Train
COORDINATED SATELLITE MEASUREMENTS OF THE EARTH’S
ATMOSPHERE
AN OVERVIEW
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Outline Radiation transfer in the Earth’s atmosphere; effects of aerosols, clouds and CO2
Afternoon constellation “A-Train” overview
Importance of formation flying
Measurements techniques like active and passive remote sensing
Spectrum of Solar Radiation Flux
O3
H2O
H2O ,CO2
O2
From Cunningham & Cunningham, 2004,
.1 . 3 .5 1 1.5 2 2.5 3 )( m 3
Major Atmospheric Windows
Effects Of Aerosol Direct effect —Scattering and absorption of radiation Indirect effect —Roles in cloud micro physics
Clean cloud Polluted cloud Large cloud droplets Small Cloud droplets Low albedo High albedo Efficient precipitation Suppressed precipitation
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How do Clouds Affect the Climate?
CirrusIce crystals
Cumulus Ice crystals/Water droplets
StratusWater droplets
Cooling effect
Warming effect
Dense clouds such ascumulus and low-altitude reflect sunlight
Thin, high-altitude cirrus clouds emits infrared radiation
Clouds Dominate the Energy Budget of the Earth
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Since the beginning of the industrial age, the concentration of CO2 has increased by about 25%, from about 280 parts per million to over 370 parts per million.
Current research indicates that continuing increases in atmospheric CO2 may modify the environment in a variety of ways.
Source: Jet Propulsion Laboratory, California Institute of Technology, Pasadena
Why Study CO2 ?
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Orbit Information
Orbit Sun synchronous, polar orbit Height -700 km Radius - 7000 km Inclination - 98.2o Time Period 98.8 minutes Make14.57 orbits in one day Repeat cycle 16days Speed 7.2 km/s All 7 members have equator crossing (ascending nodes) times 1:30 p.m.+/- 15 m Local Time
Source http://aura.gsfc.nasa.gov/instruments/index.html
Madhu GyawaliPat Arnott
Afternoon Constellation Evolution
May 4, 2002
Source http://aura.gsfc.nasa.gov/instruments/index.html
Afternoon Constellation Evolution
Aura(July-15) and PARASOL(Dec-18) joined in 2004
Source http://aura.gsfc.nasa.gov/instruments/index.html 10
CloudSat and CALIPSO joined in 2006,April-28
Afternoon Constellation Evolution
Source http://aura.gsfc.nasa.gov/instruments/index.html 11
Afternoon Constellation Evolution
Glory and OCO to be launched in 2008
Source http://aura.gsfc.nasa.gov/instruments/index.html12
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The Afternoon ConstellationIs an International Undertaking
Source : AMSR-E Science Team MeetingAugust 14-16. 2007
Constellations opportunity Coincident, and nearly
simultaneous measurementsField of Views overlapData can be correlated
Why Fly Constellations?
The whole is greater than the sum of its parts
The new A-Train observations tell us much more about weather and climate-sensitive processes than can possibly be gleaned from any one instrument alone.
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The Afternoon ConstellationIs an International Undertaking
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13.5 km AIRS IR; AMSU & HSB wave
13.5 km AIRS IR; AMSU & HSB wave
6x7 km POLDER 6x7 km POLDER
5.3 x 8.5 km TES 5.3 x 8.5 km TES
CloudCloud
0.5 km MODIS Band 3-7
0.5 km MODIS Band 3-7
0.09 km CALIPSO0.09 km CALIPSO
1. 4 km Cloudsat1. 4 km Cloudsat
OCO1x1.5 km
The Afternoon Constellation “footprints”
Remote SensingTechniques for measuring or observing an object without touching. It involves the interpretation and inversion radiometric measurements of EM radiation . Example -Optical and radio telescope, camera, Atmospheric Infrared Sounder,LIDAR,RADAR
Active and Passive Remote sensing
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Remote Sensing Tools
Long wavelengths are sensitive to large particles – cloud drops, raindrops, snowflakes, hailstones
Short wavelengths are sensitive to smallparticles –gas molecules, aerosols
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LaserTransmitter
Receiver Telescope
Scattering of light
LIght Detection And RangingRAdio Detection And Ranging
Infrared sounding ,microwave sounding
LIDARRADAR
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Remote sensing
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Spaceborn
Airborn
Groundbased
Positions of Sensor
Ground Based Remote Sensing
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To record detailed information from the surface for comparison withAircraft and/or satellite remote sensing
To observe the atmosphere from the ground (e.g. cloud base)
Advantages Low cost for transport and installation
Accessible for operatorsApplication of experimental sensorsHigh temporal coverage
Disadvantages
Low spatial coverage
Limitations in observational area
Airborne Remote Sensing
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Aircrafts, balloons ,helicopters
Advantages
Used for detailed imaging of objects or areas
Accessible for operators
Satellite under flights for validation purposes
Flexibility in choosing the operation areaHigher spatial resolution than satellite resolution
Disadvantages
Higher costs for transportation and installation
Less temporal and spatial coverage
Spaceborn Remote Sensing
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Artificial satellite ,space shuttle
High temporal and spatial coverage (global observations)
Repetitive coverage of the Earth’s surface on a continuing basis
Advantages
Can observe any portion of Earth
DisadvantagesHighest costs for transportation and installationNo accessible for operatorsVery long preparation phase
Ground Based and Airborne Coincident Remote Sensing
Source: A First course in Atmospheric Radiation, Grant W. Petty 23
Coincident measurements of the infrared emission spectrum of the cloud free atmosphere(a) 20km looking downward over the polar ice sheet and (b) at the surface looking upward
Aqua
Investigates the GLOBAL WATER CYCLE: evaporation from the oceans, water vapor , clouds, precipitation, soil moisture
Instruments: Six earth observing instruments
OVERVIEW
AIRS: Atmospheric InfRared Sounder – Obtains highly accurate temperature profiles within the atmosphere
AMSU: Advanced Microwave Sounding Unit – Obtains temperature profiles in the upper atmosphere
HSB: Humidity Sounder for Brazil – 4 Channel microwave sounder , measures humidity profiles throughout the atmosphere.
AMSR-E: Advanced Microwave Scanning Radiometer-Precipitation rate, cloud water, water vapor
MODIS: Moderate Resolution Imaging Spectroradiometer –Aerosol,cloud,temperature CERES: Clouds and the Earth's Radiant Energy System – Cloud properties, Aerosol
optical depth
Source http://www.nasa.gov/home/index.html24
MODIS
CERES
AIRS
HSB AMSR-E
AMSU-A1 AMSU-A2
Frequency750 THz 429 THz 300 GHz 0.375GHz
0.4 μm 0.7 μm
1 mm 0.8 mInfrared MicrowaveU-violet
Measurements
All measure electromagnetic radiation
All are passive instruments i.e. they simply recordradiation coming to them
Aqua Instruments
Hurricane Katrina approaching the Gulf Coast Aug. 28th 2005, MODIS
Aqua covers wide range of Earth scienceUV + VISIBLE + IR + Microwave
Source http://www.nasa.gov/home/index.html25
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The Aura satellite provides us the first global view of the Earth's atmosphere.
HIRDLS: HIgh Resolution Dynamics Limb Sounder – global distribution of temperature and composition of the atmosphere
MLS: Microwave Limb Sounder –stratospheric temperature and upper tropospheric constituents
OMI : Ozone Monitoring Instrument – Distinguishes between aerosol types, tropospheric ozone.
TES: Tropospheric Emission Spectrometer – all radiatively active molecular species in the Earth's lower atmosphere.
Aura
Nadir view Limb View
TES
Instruments Source http://aura.gsfc.nasa.gov/instruments/index.html
Source http://aura.gsfc.nasa.gov/instruments/index.html
Measurements
HIRDLS in yellow, OMI(has a cross track swath of 2600km) in blue, MLS in green, and TES in red.
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PARASOL
Measures radiative and microphysical properties of clouds and aerosols by measuring the directionality and polarization of light reflected by the earth-atmosphere-ocean system
(Polarization and Anisotropy of Reflectances for Atmospheric Science coupled with Observations from a LIDAR)
POLDER (POLarization and Directionality of the Earth’s Reflectance)
A rotating wheel scans 9 wavelength bands(443-1029 nm)
A target is viewed up to 16 times with various viewing angles
Three of the channels (490,670,865 nm) also measures linear polarization,Lidar 1064 nm 532 nm
Instrument
Source: CNES
Measurements Polarization distinguishes the liquid phase clouds and ice-phase clouds ,as the former has strong peak of polarization
The cloud level pressure (or altitude)is measured by using the differential absorption technique
PARASOL can discriminate large spherical marine aerosols from non-spherical desert aerosols
PARASOL first images over Europe(2005 January):natural(left) and polarized(right)
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CALIPSO
Three instrumentsCALIOP : Cloud-Aerosol Lidar with Orthogonal
Polarization - Two wavelength polarization-sensitive Lidar (532 and 1064 nm) that provides high-resolution vertical profiles of aerosols and clouds
WFC: Wide Field Camera - Fixed, nadir-viewing imager with a spectral channel covering the 620-670 nm region
IIR: Imaging Infrared Radiometer - Nadir-viewing, non-scanning imager
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations
30The orange and red colors signify regions of fine aerosols – that suspended above Earth’s surface.
CALIPSO’s polarization lidar instrument can detect aerosol Particles and can distinguish between aerosol and cloudparticles
0 A
ltitu
de
km
Measurement
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CPR: Cloud Profiling Radar - A 94-GHz nadir-looking radar
Will advance our understanding of cloud abundance, distribution, structure, and radiative properties.
Able to detect the much smaller particles of liquid water and ice (ground-based weather radars use centimeter wavelengths)
CloudSat
Cloud Profiling Radar
Measures the power backscattered by clouds as a function of distance from the radar.
Instruments
Tight formation flying of CALIPSO and CloudSat- seperated by 15 s
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A fraction of these pulses reflect back while others
continue downward, some being absorbed
Radar measures the time delay and magnitude of the reflected
signal
Measurements
CALIPSO and CloudSat will provide the first statistics on the vertical structure of clouds. For the first time ,we will see clouds from their tops to their bottoms-like getting CT scan of clouds from space
Provide the first validated estimate of how much clouds and aerosols contribute to the vertical distribution of atmospheric warming
CALIPSO +CLOUDSAT MISSION
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Future MissionsSchedule date: Dec-15,2008
Instrument
Three grating spectrometers to measure at 2.06um and 1.61um,and 760nm for the Oxygen A-band .
OCO: Orbiting Carbon ObservatoryWill make first space based measurements of
column CO2 to quantify sources and sinks of CO2
Source: Jet Propulsion Laboratory, California Institute of Technology, Pasadena
Glory
OCO
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Will make the measurements of the Earth's energy balance and the effect of black carbon soot and other aerosols in the atmosphere
Instrument
Aerosol Polarimetry Sensor -continuous scanning sensor that collect visible, near infrared, and short-wave infrared data scattered from aerosols and clouds.
Total Irradiance Monitor(TIM) will collect high accuracy, high precision measurements of total solar irradiance
Will measure the total solar irradiance to determine the Sun's direct and indirect effect on
the Earth's climate.
Glory Launch Date: December 2008 Launch Site: Vandenberg AFB, California
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Sun synchronous satellites have many advantages than other satellites like geo stationary, as they offer higher resolution, carry many instruments and can observe at many more wavelengths.
The A-Train formation allows for coordinated and coincidence measurements. Also there are several complementary differences among the way the different instruments in the constellation observe the same object or process.
New data from NASA's A-Train constellation, coupled with recent advances in climate modeling, creates a rare opportunity to advance understanding of the interaction of atmospheric constituents and their climate consequence
Summary
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THANK YOU
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The “NASA-A Train“ constellation of seven Earth–orbiting satellites remotely sense Clouds , aerosols, water vapor, and trace gases such as CO2,NO2, and O3. The satellites orbit sun –synchronously at an altitude of 705 km with Aqua in the lead ,followed in order by CALIPSO,CloudSat,PARASOL,and Aura. With Aqua in the lead and Aura at the tail this formation has been termed the afternoon constellation or A-Train, and all satellites cross the equator within a few minutes around 1:30 pm local time. These satellites employ revolutionary measurement methods to probe the Earth’s atmosphere, and will improve our weather and climate forecasts. Data from these satellites can be used together to obtain comprehensive information about atmospheric processes. This talk will give an over view of the active and passive remote sensing.Measurement techniques used on satellite as well as description of the importance of the atmospheric properties being measured. A discussion will be presented on the importance of synergistic measurements of satellite suite.
ABSTRACT
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