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ESMESM 266:266: ThermalThermal infraredinfrared
remoteremote sensingsensinggg
(Wikipedia – Infrared)
InfraredInfrared remoteremote sensing,sensing, toto measuremeasure ……
- Surface temperature, through the atmosphere
- Atmospheric sounding T t d h idit
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- Temperature and humidity
- Trace gas concentrations
- Radiation balance
- Emissivity
- Antenna on roof of Ellison Hall
- http://www.icess.ucsb.edu/ and follow link to DATA->AVHRR Images
AVHRRAVHRR (NOAA’s(NOAA’s operationaloperational meteorologicalmeteorological sensor)sensor)
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FusionFusion betweenbetween datadata onon oceanocean temperaturetemperature andand surfacesurface heightheight
TeraScan
calibrate, de-cloud, aggregate extrapolate HRPT downlink AVHRR image SST “super data” SST grid
HRPT Data Handling HRPT Gridding
SST (^) u SST t
∂ ∂
CD-ROM
g p g
MGDRcracker aggregatecalibrate, extrapolate
ocean height “super data” ocean height TOPEX points grid
GOAL : Local and advective components of upper ocean heat balance:
TOPEX Gridding TOPEX Data Handling
RadiationRadiation principlesprinciples
- All bodies radiate
- Hotter bodies radiate more at all wavelengths R di ti f h tt b d k t
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- Radiation from a hotter body peaks at a shorter wavelength than from a cooler body
GoverningGoverning equationequation
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(^2) , where x 1 L hc^ x hc λ λ e k λ T = = −
Planck’s equation (spectral curves on next slide) S f B l ∞
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c speed of light 3.00× 10 8 ms – h Planck’s constant (^) 6.63× 10 –34^ Js k Boltzmann’s constant 1.38× 10 –23^ JK– σ Stefan-Boltzmann constant 5.67× 10 –8^ Wm–2^ K –
Stefan-Boltzmann equation
4 0
E = π ∫ L d λ λ =σ T
DefinitionDefinition ofof IRIR regionsregions
1.0E+
1.0E+
1.0E+
1.0E+ Sun (5800K)Scaled for Earth-Sun distance Earth (288K)
1.0E-01 8
1.0E+
1.0E+
1.0E+
1.0E+
1.0E+
0.1 1 10 100 wavelength (μm)
radiance
NIR SWIR
Mid IR Thermal IR
AtmosphericAtmospheric transmissiontransmission ofof infraredinfrared radiationradiation
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http://www.pentec.com/instrumentation.htm
InfraredInfrared spectralspectral regionsregions
attributes disadvantages 3.5–4.5 μ m (Mid IR)
Clearest atmospheric window and finest spatial resolution for
Cloud cover. Less energy than 8–12 μm. Mixed with solar
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spatial resolution for measuring temper- ature.
Mixed with solar radiation in daytime.
8–12 μ m (Thermal IR)
Atmospheric window. Peak of energy emitted from Earth. Most accurate temper- atures.
Cloud cover. Coarser spatial resolution than MWIR.
EmissivityEmissivity——objectsobjects areare notnot blackbodiesblackbodies
- Kirchhof’s Law: emissivity = absorptance
- Probability of emission of a photon at a given frequency and angle is same as probability of absorption at same frequency and angle
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p q y g
- Emissivity + Reflectance + Transmittance = 1 - (all functions of wavelength and angle)
DefinitionDefinition ofof brightnessbrightness temperaturetemperature TTBB
2 2 5 5
hc k TB (^) 1 hc k T 1
hc hc e e hc
λ ε^ λ θ^ λ λ λ
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So 1 ln
Or ln 1 B
B (^) hc k T
hc k T
hc T e k
hc T k e
λ
λ
ε λ ε
λ ε ε
ASTERASTER spectralspectral bandsbands onon modelmodel atmosphereatmosphere
MODISMODIS——ModerateModerate‐‐ResolutionResolution ImagingImaging SpectroradiometerSpectroradiometer
- 36 bands, 1 in SWIR, 6 in mid IR, 10 in thermal IR
- Measurements of S f / l d t t
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- Surface/cloud temperature
- Atmospheric temperature
- Cirrus clouds and water vapor
- Ozone
- Cloud top altitude
AIRSAIRS——AdvancedAdvanced InfraredInfrared SounderSounder
- 2400 bands in IR (3.7-15 μm) and 4 bands in visible (0.4-1.0 μm) - Absorption “signature” around 4.2 μm and 15 μm (CO 2 ) and 6 3 μm (H 2 O) enables
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μm (CO 2 ) and 6.3 μm (H 2 O) enables temperature and humidity sounding to 1 km vertical resolution
- Spatial resolution is 13.5 km
- Complemented by microwave sounders to deal with clouds
HIRDLSHIRDLS——HighHigh‐‐ResolutionResolution DynamicDynamic LimbLimb SounderSounder
- Sound upper troposphere, stratosphere, and mesosphere for temperature and a variety of gases O H O CH N O NO HNO N O CFC
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- O 3 , H 2 O, CH 4 , N 2 O, NO 2 , HNO 3 , N 2 O 5 , CFC- 11, CFC-12, ClONO 2
- 21 bands from 6.12 μm to 17.76 μm
TESTES——TroposphericTropospheric EmissionEmission SpectrometerSpectrometer
- High-resolution infrared-imaging Fourier transform spectrometer - Spectral coverage of 3.2 to 15.4 μm at a spectral resolution of 0 025 cm –
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spectral resolution of 0.025 cm
- Line-width-limited discrimination of most radiatively active gases in the Earth's lower atmosphere
OperationalOperational MissionsMissions
- GOES (Geostationary Operational Environmental Satellites)
- POES (Polar-Orbiting Environmental Satellites, i.e. AVHRR)
- Two satellites provide coverage with maximum delay of 6 hours Latest is NOAA 15 launched May 13 1998
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- Latest is NOAA-15, launched May 13, 1998
- NPOESS (National Polar-Orbiting Environmental Satellite System)
- Joint NOAA/NASA/DoD mission
- Launch no earlier than 2011
- Imaging, microwave, and sounding instruments
LandLand surfacesurface temperaturetemperature fromfrom MODISMODIS
- Go to the MODIS Land Global Browse page
- Select the MOD11/MYD11 checkbox (Surface Temperature)
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(Surface Temperature)
- Enter date range
- Select satellite (Terra and/or Aqua)
- Select Collection (5 is most recent)
ActiveActive firefire detectiondetection
- MODIS Fire and Thermal Anomaly
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Anomaly website
OceanOcean surfacesurface temperaturetemperature fromfrom MODISMODIS
- MODIS ocean web site
- Click on Quality Assurance to get the browse tool [intuitive?]
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HowHow doesdoes allall thisthis work?work?
- As noted in previous lecture, a great feature of NASA’s EOS program is that the algorithms are peer-reviewed and published in algorithm theoretical basis documents
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- Each instrument has a page with links to these ATBDs, e.g. for MODIS, one can go to Zhengming Wan’s ATBD for land surface temperature - The algorithm uses MODIS bands 31 (10.78- 11.28μm) and 32 (11.77-12.27μm)
Dr.Dr. Wan’sWan’s equationequation isis
1 2 3 2 31 32
1 2 3 2 31 32
1 2 1 2
s T C A A A T^ T
B B B T^ T
ε ε ε ε ε ε ε ε
= + ⎛^ + −^ + Δ⎞ + ⎜⎝ ⎟⎠
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31 32 (^31 3231 )
2 where , brightness temperatures in bands 31, = 2 and , , coefficients given by multidimensional lookup
T T
A B C
ε ε
ε^ ε^ ε ε ε ε
⎝ ⎠
tables (they depend on angle)
SpectralSpectral emissivityemissivity librarylibrary
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