Meteorolojik Uzaktan Algılamaya Giriş Erdem Erdi Uzaktan Algılama Şube Müdürlüğü 7-8 Mayıs...
-
Upload
arline-madeleine-ellis -
Category
Documents
-
view
246 -
download
6
Transcript of Meteorolojik Uzaktan Algılamaya Giriş Erdem Erdi Uzaktan Algılama Şube Müdürlüğü 7-8 Mayıs...
Meteorolojik Uzaktan Algılamaya Giriş
Erdem ErdiUzaktan Algılama Şube Müdürlüğü
7-8 Mayıs 2012, İzmir
Outline
Visible: RGB, Radiance and Reflectance
Near Infrared: Absorption
Infrared: Radiance and Brightness Temperature
Sensor Geometry
Sensor
Optics
Electronics
Terminology of radiant energy
Energy from the Earth Atmosphere
Flux
over time is
which strikes the detector area
Irradiance
at a given wavelength interval
MonochromaticIrradiance
over a solid angle on the Earth
Radiance observed by satellite radiometer
is described by
can be inverted to
The Planck function
Brightness temperature
Definitions of Radiation__________________________________________________________________
QUANTITY SYMBOL UNITS__________________________________________________________________
Energy dQ Joules
Flux dQ/dt Joules/sec = Watts
Irradiance dQ/dt/dA Watts/meter2
Monochromatic dQ/dt/dA/d W/m2/micron Irradiance
or
dQ/dt/dA/d W/m2/cm-1
Radiance dQ/dt/dA/d/d W/m2/micron/ster
or
dQ/dt/dA/d/d W/m2/cm-1/ster__________________________________________________________________
All MSG channels• Channel 01: VIS 0.6 • Channel 02: VIS 0.8 • Channel 03: NIR 1.6 Channel 04: MIR 3.9 Channel 05 WV 6.2 Channel 06: WV 7.3 Channel 07: IR 8.7 Channel 08: IR 9.7 („Ozon“) Channel 09: IR 10.8 Channel 10: IR 12.0 Channel 11: IR 13.4 („CO2“) Chanell 12: HRV (High Resolution Visible)
Visible(Reflective Bands)
Infrared(Emissive Bands)
Visible: Reflective Bands
Used to observe solar energy reflected by the Earth system in the:
• Visible between .4 and .7 µm • NIR between .7 and 3 µm
About 99% of the energy observed between 0 and 4 µm is solar reflected energy
Only 1% is observed above 4 µm
Sun radiation Earth radiation
Ch01: 0.6 Ch02: 0.8 Ch03: 1.6
Wavelength (micron)
Ozone
Watervapour
Carbondioxid
Watt/m2 andmicron
Comparison of radiation sources sun - earth
For wave length < 5 m solar radiation is dominant For wave length > 5 m radiation of earth is dominant
only VIS
VIS +IR
only IR
• Ch01, 02, 03, 12: only sun radiation • Ch04: both: radiation from sun and earth • Ch 05, 06, 07, 08, 09, 10, 11: only thermal earth radiation
Sun radiation Earth radiation
Watt/m2
andmicron
Reflectance To properly compare different reflective channels we need
to convert observed radiance into a target physical property
In the visible and near infrared this is done through the ratio of the observed radiance divided by the incoming energy at the top of the atmosphere
The physical quantity is the Reflectance i.e. the fraction of solar energy reflected by the observed target
Soil
Vegetation
Snow
Ocean
VIS 0.6 and VIS 0.8: land surface In VIS 08 better recognition of
surface structures because of higher reflectance of soil and leafs
0.6 0.8
Ch01: 0.6
Ch02: 0.8
NIR 1.6: cloud Different appearance of ice - and waterclouds because of
stronger absorption in the icephase Waterclouds: white Iceclouds: black
icecloud
watercloud
0.6 0.8 1.6
Snow/Ice: low reflectivity
Cloud: high reflectivity
After source: EUMETSAT
Different Reflectivity of Ice/snow and Watercloud in 1.6
0.6 0.8 1.6
Big difference between snow/ice and water clouds
No difference between snow/ice and water clouds
After source: EUMETSAT
Different Reflectivity of Ice/snow versus Watercloud in 0,6, 0,8 and 1.6
?? ??
??
??
cloud
snow
earth
0.6
?? ??
??
??
cloud
snow
earth
0.8
cloud
snow
earth
1.6
Ch01:0.6
Only signals fromreflected solar radiation
Different greyshades:different reflectivity;earth: dark
Ch02:0.8
Only signals fromreflected solar radiation
Different greyshades:different reflectivity;earth: grey;higher reflectance ofearth surface than in 0.6
Transparent clouds:
Band 201.38 micron
Channel 12
HRV
Solar energy spectrum
27
Land Surface Channel 01 (VIS0.6) Clouds High reflectanceHigh reflectance
Very thick clouds
Very thin clouds over land
Very thin clouds over ocean
Low reflectanceLow reflectance
Sun GlintSnow
Desert
Bare Soil
Forest
Ocean, Sea
31 October 2003, 11:30 UTC
28
Land Surface Channel 02 (VIS0.8) Clouds
Sun GlintSnow
Desert
Gras, Rice fields
Forest
Bare Soil
Ocean, Sea
31 October 2003, 11:30 UTC
High reflectanceHigh reflectance
Very thick clouds
Very thin clouds over land
Very thin clouds over ocean
Low reflectanceLow reflectance
29
Land Surface Channel 03 (NIR1.6) Clouds High reflectanceHigh reflectance
Water clouds with small droplets
Water clouds with large droplets
Ice clouds with small particles
Ice clouds with large particles
Low reflectanceLow reflectance
Sun Glint Sand Desert
Gras, Rice fields
Forest
Bare Soil
SnowOcean, Sea
31 October 2003, 11:30 UTC
30
Land Surface Channel 12 (HRVIS) Clouds
31 October 2003, 11:30 UTC
Sun GlintSnow
Desert
Bare Soil
Forest
Ocean, Sea
High reflectanceHigh reflectance
Very thick clouds
Very thin clouds over land
Very thin clouds over ocean
Low reflectanceLow reflectance
Cb clouds over Nigeria as seen in the high-res. visible channelMSG-1, 24 April 2003, 08:00 UTC
Visible 0.6 m High-res. Visible
Cirrus clouds over the Algerian desert as seen in the high-res. visible channelMSG-1, 9 May 2003, 14:00 UTC
Visible 0.6 m High-res. Visible
Von Karman Vortex Streets as seen in the high-res. visible channelMSG-1, 6 June 2003, 09:00 UTC
Visible 0.8 m High-res. Visible
MSG-18 September 200315:00 UTCRGB CompositeR = HRVG = HRVB = IR10.8i
Thin CirrusCirrus Outflow
Overshooting Top
Low-Level CloudsMonitoring of
Fine-Scale Structures with the
HRV Channel
Niger
MSG-15 June 200314:45 UTCRGB CompositeR = HRVG = HRVB = IR10.8i
Monitoring of Fine-Scale
Structures with the HRV ChannelThick Cb Cloud
Thin Cirrus Anvil
Visible(Reflective Bands)
Infrared(Emissive Bands)
Emissive Bands
Used to observe terrestrial energy emitted by the Earth system in the IR between 4 and 15 µm
• About 99% of the energy observed in this range is emitted by the Earth
• Only 1% is observed below 4 µm• At 4 µm the solar reflected energy can significantly affect
the observations of the Earth emitted energy
Spectral Characteristics of Energy Sources and Sensing Systems
IR
4 µm11 µm
Brightness Temperature To properly compare different emissive channels
we need to convert observed radiance into a target physical property
In the Infrared this is done through the Planck function
The physical quantity is the Brightness Temperature i.e. the Temperature of a black body emitting the observed radiance
All MSG channels Channel 01: VIS 0.6 Channel 02: VIS 0.8 Channel 03: NIR 1.6 Channel 04: MIR 3.9 Channel 05 WV 6.2 Channel 06: WV 7.3 • Channel 07: IR 8.7 Channel 08: IR 9.7 („Ozon“)• Channel 09: IR 10.8 • Channel 10: IR 12.0 Channel 11: IR 13.4 („CO2“) Chanell 12: HRV (High Resolution Visible)
42
Land Surface Channel 04 (IR3.9) Clouds Daytime
High reflectance / High reflectance / WarmWarm
Low-level Water Clouds (land)
Low-level Water Clouds (sea)
Cold Ice Clouds (small particles)
Cold Ice Clouds (large particles)
Low Reflectance / Low Reflectance / ColdCold
Sun Glint Fires
Hot Sand Desert
Warm Tropical Areas
Cold Land
Ocean, Sea
Cold Snow
31 October 2003, 11:30 UTC
43
Land Surface Channel 04 (IR3.9) Clouds Nighttime
WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold
Fires
Warm Surfaces (tropical oceans,
seas, lakes)
Cold Surfaces (arctic ice areas)
29 October 2003, 02:00 UTC
44
Water Vapour Channel 05 (WV6.2) Clouds WarmWarm
High-level Clouds
ColdCold
Low UTH
High UTH
31 October 2003, 11:30 UTC
45
Water Vapour Channel 06 (WV7.3) Clouds WarmWarm
Mid-level Clouds
High-level Clouds
ColdCold
Low MTH
High MTH
(High-level warm surfaces)
31 October 2003, 11:30 UTC
46
Land Surface Channel 07 (IR8.7) Clouds WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold31 October 2003, 11:30 UTC
Hot Land Surf.
Warm Sea Surf. (tropical oceans,
seas, lakes)
Cold Land Surf. (arctic ice areas)
47
Land Surface Channel 08 (IR9.7) Clouds WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold31 October 2003, 11:30 UTC
Hot Land Surf.
Warm Sea Surf. (tropical oceans,
seas, lakes)
(Areas of high IPV)
Cold Land Surf. (arctic ice areas)
48
Land Surface Channel 09 (IR10.8) Clouds WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold31 October 2003, 11:30 UTC
Hot Land Surf.
Warm Sea Surf. (tropical oceans,
seas, lakes)
Cold Land Surf. (arctic ice areas)
49
Land Surface Channel 10 (IR12.0) Clouds WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold31 October 2003, 11:30 UTC
Hot Land Surf.
Warm Sea Surf. (tropical oceans,
seas, lakes)
Cold Land Surf. (arctic ice areas)
50
Land Surface Channel 11 (IR13.4) Clouds WarmWarm
Low-level Clouds
Mid-level Clouds
High-level Clouds
ColdCold31 October 2003, 11:30 UTC
Hot Land Surf.
Warm Sea Surf. (tropical oceans,
seas, lakes)
Cold Land Surf. (arctic ice areas)
Conclusions• Radiance is the Energy Flux (emitted and/or reflected by
the Earth) which strikes the Detector Area at a given Spectral Wavelength (wavenumber) over a Solid Angle on the Earth;
• Reflectance is the fraction of solar energy reflected to space by the target;
Given an observed radiance, the Brightness Temperature is the temperature, in Kelvin, of a blackbody that emits the observed radiance;
Knowing the spectral reflective (Vis) and emissive (IR) properties (spectral signatures) of different targets it is possible to detect: clouds, cloud properties, vegetation, fires, ice and snow, ocean color, land and ocean surface temperature ……