Meteorolojik Uzaktan Algılamaya Giriş Erdem Erdi Uzaktan 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 Monochromatic Irradiance 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 __________________________________________________________________ QUANTITYSYMBOLUNITS __________________________________________________________________ EnergydQJoules FluxdQ/dtJoules/sec = Watts IrradiancedQ/dt/dAWatts/meter 2 MonochromaticdQ/dt/dA/d W/m 2 /micron Irradiance or dQ/dt/dA/d W/m 2 /cm -1 RadiancedQ/dt/dA/d /d  W/m 2 /micron/ster or dQ/dt/dA/d /d  W/m 2 /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 05WV 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  („CO 2 “) 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 Water vapour Carbon dioxid Watt/ m 2 and micron

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/ m 2 and micron

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 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

Snow/Ice: low reflectivity Cloud: high reflectivity After source: EUMETSAT Different Reflectivity of Ice/snow and Watercloud in 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 from reflected solar radiation Different greyshades: different reflectivity; earth: dark

Ch02:0.8 Only signals from reflected solar radiation Different greyshades: different reflectivity; earth: grey; higher reflectance of earth surface than in 0.6 Transparent clouds:

Band micron

Channel 12 HRV Solar energy spectrum

27 Land Surface Channel 01 (VIS0.6) Clouds High reflectance Very thick clouds Very thin clouds over land Very thin clouds over ocean Low reflectance Sun Glint Snow Desert Bare Soil Forest Ocean, Sea 31 October 2003, 11:30 UTC

28 Land Surface Channel 02 (VIS0.8) Clouds Sun Glint Snow Desert Gras, Rice fields Forest Bare Soil Ocean, Sea 31 October 2003, 11:30 UTC High reflectance Very thick clouds Very thin clouds over land Very thin clouds over ocean Low reflectance

29 Land Surface Channel 03 (NIR1.6) Clouds High reflectance Water clouds with small droplets Water clouds with large droplets Ice clouds with small particles Ice clouds with large particles Low reflectance Sun Glint Sand Desert Gras, Rice fields Forest Bare Soil Snow Ocean, Sea 31 October 2003, 11:30 UTC

30 Land Surface Channel 12 (HRVIS) Clouds 31 October 2003, 11:30 UTC Sun Glint Snow Desert Bare Soil Forest Ocean, Sea High reflectance Very thick clouds Very thin clouds over land Very thin clouds over ocean Low reflectance

Cb clouds over Nigeria as seen in the high-res. visible channel MSG-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 channel MSG-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 channel MSG-1, 6 June 2003, 09:00 UTC Visible 0.8  m High-res. Visible

MSG-1 8 September :00 UTC RGB Composite R = HRV G = HRV B = IR10.8i Thin Cirrus Cirrus Outflow Overshooting Top Low-Level Clouds Monitoring of Fine-Scale Structures with the HRV Channel Niger

MSG-1 5 June :45 UTC RGB Composite R = HRV G = HRV B = IR10.8i Monitoring of Fine-Scale Structures with the HRV Channel Thick 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 µm 11 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 05WV 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  („CO 2 “) Chanell 12:HRV (High Resolution Visible)

42 Land Surface Channel 04 (IR3.9) Clouds Daytime High reflectance / Warm Low-level Water Clouds (land) Low-level Water Clouds (sea) Cold Ice Clouds (small particles) Cold Ice Clouds (large particles) Low Reflectance / Cold 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 Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 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 Warm High-level CloudsCold Low UTH High UTH 31 October 2003, 11:30 UTC

45 Water Vapour Channel 06 (WV7.3) Clouds Warm Mid-level Clouds High-level CloudsCold Low MTH High MTH (High-level warm surfaces) 31 October 2003, 11:30 UTC

46 Land Surface Channel 07 (IR8.7) Clouds Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 31 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 Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 31 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 Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 31 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 Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 31 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 Warm Low-level Clouds Mid-level Clouds High-level CloudsCold 31 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 ……