RS Education2

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RS EducationRS Education

Part 2

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Spatial ResolutionSpatial Resolution size of the smallest possible feature that can be detected

• Lp/mm (Line pairs per millimeter)

• Instantaneous Field of View (IFOV)

• Pixel Size

- high resolution images, small objects can be detected.

- the finer the resolution, the less total ground area

• Scale

(ratio of distance on an image or map, to actual ground distance)

- Large Scale (e.g. 1:5000)

- Small Scale (e.g. 1:100000)

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Spectral ResolutionSpectral Resolution The ability of a sensor to define fine wavelength intervals

The finer the spectral resolution, the narrower the wavelength range for a particular channel or band

• Pan Images

• Color Images

• Multispectral Images

• Hyperspectral images

Pan Images have greater Spatial resolution

than the MSSs because of received energy

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Radiometric ResolutionRadiometric Resolution

sensitivity to the magnitude of the electromagnetic energy

The finer the radiometric resolution of a sensor, the more sensitive it is to detecting small differences in reflected or emitted energy.

Depends on number of bits

8 bit sensor 2 8 =256 Digital Values (0-255)There are trade-offs between spatial, spectral, and radiometric resolution which must be taken into consideration when engineers design a sensor.

high spatial resolution small IFOV reduce of the amount of energy reduced radiometric resolution …

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Temporal ResolutionTemporal Resolution

The Revisit time or the length of time it takes for a satellite to complete one entire orbit cycle.

The actual temporal resolution of a sensor depends on a variety of factors, including the satellite/sensor capabilities, the swath overlap, and latitude.

• Multi temporal Imagery is important when

- persistent clouds offer limited clear views of the Earth's surface (often in the tropics) - short-lived phenomena (floods, oil slicks, etc.) need to be imaged - multi-temporal comparisons are required (e.g. the spread of a forest disease from one year to the next) - The changing appearance of a feature over time can be used to distinguish it from near-similar features (wheat / maize)

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Cameras and Aerial PhotographyCameras and Aerial Photography

Framing systems

• Photographic films: sensitive to light from 0.3 mm to 0.9 mm in wavelength covering the ultraviolet (UV), visible, and near-infrared (NIR).

• Panchromatic films: sensitive to the UV and the visible portions of the spectrum

The ground coverage of a photo depends on the focal length of the lens, the platform altitude, and the format and size of the film.

Vertical and Oblique photographs, Stereoscope, Photogrammetry

Instead of using film, digital cameras use a gridded array of silicon coated CCDs (charge-coupled devices) that individually respond to electromagnetic radiation

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Multispectral ScanningMultispectral Scanning

Multispectral Scanners (across-track scanning, along-track scanning)

• across-track scanners (whiskbroom scanners)

Scanning (Rotating mirror (A), detectors (B))

Spatial resolution depends on IFOV and platform Height.

dwell time: the length of time the IFOV "sees" a ground resolution cell as the rotating mirror scans which is generally quite short and influences the design of the spatial, spectral, and radiometric resolution of the sensor.

• along-track scanners (Pushbroom Scanners)

Scanning (array of detectors (A), focal plane (B), lens systems (c))

A separate linear array is required to measure each spectral band or channel.

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Multispectral ScanningMultispectral Scanning

Advantages of Along-Track scanners over Across-Track scanners:

• increased Dwell time increased detected energy

• Solid state, smaller, lighter, less needed power

because they have no moving part

Disadvantage: cross-calibrating thousands of detectors to achieve uniform sensitivity across the array is necessary and complicated.

Advantages of Scanning systems over photographic systems:

• increased spectral range

• increased Spatial Resolution

• no need to separate lens system for detecting different bands

• increased dynamic range by electronically recording energy

• more easy to transmit data and processing

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Thermal ImagingThermal ImagingThermal spectral Band (3-15µm)

The detectors are cooled to temperatures close to absolute zero in order to limit their own thermal emissions.

Thermal sensors essentially measure the surface temperature and thermal properties of targets.

The data are generally recorded on film and/or magnetic tape and the temperature resolution of current sensors can reach 0.1 °C

Imagery which portrays relative temperature differences in their relative spatial locations are sufficient for most applications. Absolute temperature measurements may be calculated but require accurate calibration and measurement of the temperature references and detailed knowledge of the thermal properties of the target, geometric distortions, and radiometric effects.

The Spatial resolution of Thermal images are lower because the emitted energy decreases by increasing wavelength.

Thermal images can be acquired

Day/night

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How would thermal imagery be useful in an urban environment?

Detecting and monitoring heat loss from buildings in urban areas is an excellent application of thermal remote sensing

Thermal imaging in both residential and commercial areas allows us to identify specific buildings, or parts of buildings, where heat is escaping

Thermal ImagingThermal Imaging

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Geometric Distortion in ImageryGeometric Distortion in Imagery

Any remote sensing image (acquired by multispectral scanner on satellite/ a photographic system/ other platform/sensor combination) will have various geometric distortions due to:

• The perspective of the sensor optics, • The motion of the scanning system, • The motion and instability of the platform, • The platform altitude, attitude, and velocity, • The terrain relief, and • The curvature and rotation of the Earth.

And the errors are:• Relief displacement (photographic, along-track & across-track Sensors)• Errors caused by changes in their speed, altitude, and attitude

This is more important in aircraft platforms because of satellite’s stable orbits

• Skew Distortion (caused by Earth rotation)

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If you wanted to map a mountainous region, limiting geometric distortions as much as possible, would you choose a satellite-based or aircraft-based scanning system?

Although an aircraft scanning system may provide adequate geometric accuracy in most instances, a satellite scanner would probably be preferable in a mountainous region. Because of the large variations in relief, geometric distortions as a result of relief displacement would be amplified at aircraft altitudes much more than from satellite altitudes. Also, given the same lighting conditions, shadowing would be a greater problem using aircraft imagery because of the shallower viewing angles and would eliminate the possibility for practical mapping in these areas.

Geometric Distortion in ImageryGeometric Distortion in Imagery

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some specific satellite sensors some specific satellite sensors

operating in the operating in the visiblevisible and and infraredinfrared portions of the spectrum portions of the spectrum. .

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WeatherWeather Satellites/Sensors Satellites/Sensors

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Weather Satellites/SensorsWeather Satellites/Sensors

Weather monitoring and forecasting was one of the first civilian applications of satellite remote sensing

TIROS-1 (Television and Infrared Observation Satellite - 1)

First Weather Satellite launched in 1960 by the United States

ATS-1 (Applications Technology Satellite-1)

- First Geostationary Satellite launched in 1966 by NASA

- provided hemispheric images of the Earth's surface,

atmospheric moisture and cloud cover every half hour

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GOES (Geostationary Operational Environmental Satellite)

- placed in geostationary orbits 36000 km above the equator

- Each view approximately one-third of the Earth

First Generation:

- GOES-1 (launched 1975) through GOES-7 (launched 1992)

Second Generation:

- GOES-8 (launched 1994) and others

- provide images as often as every 15 minutes.

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GOES

- Imager instrument : - 5 channels in Visible and IR -10 bit radiometric resolution

- Sounder instrument :

- 18 thermal IR bands & 1 visible

- 13 bit radiometric resolution

- Spatial resolution of 8 km

- data are used for

- surface and cloud-top temperatures

- multi-level moisture profiling in the atmosphere

- ozone distribution analysis.

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NOAA/AVHRR (Advanced Very High Resolution Radiometer)

• sun-synchronous, near-polar orbits (830-870 km above the Earth)

• Two satellites of NOAA provide data from same region in less than six hours

• swath width of 3000 km

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NOAA/AVHRR (Advanced Very High Resolution Radiometer)

• Applications

- Weather prediction - Natural Vegetation

- Sea Surface Temperature - Crop conditions

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NOAA/AVHRR Image

Iran, 30-12-2003

Band 1

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NOAA/AVHRR Image

Iran, 30-12-2003

Band 2

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NOAA/AVHRR Image

Iran, 30-12-2003

Band 3

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NOAA/AVHRR Image

Iran, 30-12-2003

Band 4

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NOAA/AVHRR Image

Iran, 30-12-2003

Band 5

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DMSP (Defense Meteorological Satellite Program)

• One of United States series of satellites

• near-polar orbiting satellites

• sensor name: Operational Linescan System (OLS)

• twice daily coverage

• swath width of 3000 km

• spatial resolution of 2.7 km

• two fairly broad wavelength bands:

- a visible and near infrared band (0.4 to 1.1 mm)

- a thermal infrared band (10.0 to 13.4 mm)

• able to acquire visible band night time imagery under very low illumination conditions. With this sensor, it is possible to collect striking images of the Earth showing (typically) the night time lights of large urban centers.

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Weather Satellites/SensorsWeather Satellites/SensorsGMS

• Launched by Japan

• geostationary satellite situated above the equator over Japan

• half-hourly imaging of the Earth

• Two spectral Bands:

- 0.5 to 0.75 mm (1.25 km resolution)

- 10.5 to 12.5 m m (5 km resolution)

Meteosat

• Launched by consortium of European communities

• geostationary satellite situated above the equator over Europe

• half-hourly imaging of the Earth

• Three spectral Bands:

- visible band (0.4 to 1.1 mm; 2.5 km resolution)

- mid-IR (5.7 to 7.1 mm; 5 km resolution)

- thermal IR (10.5 to 12.5 mm; 5 km resolution)

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Land Observation Land Observation

Satellites/SensorsSatellites/Sensors

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QuickBirdQuickBirdSatelliteSatellite

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Land Observation Satellites/SensorsLand Observation Satellites/Sensors

QuickBird satellite

• In 2000, QuickBird 1 was failed to reached its orbit.

• Launch date: October 18, 2001

• Altitude: 450 km - 98 degree, sun-synchronous inclination

• Temporal resolution: 1-3.5 days

• Stereo pairs: available

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QuickBird sensor

• Spatial resolution: 61cm (PAN at Nadir)

2.44m (Multispectral at Nadir)

• radiometric resolution: 11 bits

• Spectral resolution: 4 spectral bands

Blue: 450 to 520 nanometers

Green: 520 to 600 nanometers

Red: 630 to 690 nanometers

Near-IR: 760 to 900 nanometers

PAN

• Temporal resolution: 1-3.5 days

• Swath Width: 16.5 Km

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IkonosIkonosSatelliteSatellite

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Ikonos Satellite

• IKONOS is the Greek from word for "image"

• Ikonos-1 was planned for launch in 1999 but the launch failed.

• Ikonos-2 was launched on Sep. 24, 1999, but was renamed to Ikonos-1

• Orbit: polar, circular, sun-synchronous 681-km, 98.1 degrees

• Passing time at descending node: 10:30 a.m

• life span: 5-7 years

• exact repeat pass: 35 days

• Stereo pairs: available

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Ikonos Sensor

• Image scene size: 11.3 km by 11.3 km

• Revisit Frequency: 3 to 4 days

• radiometric resolution: 11 bits

• products Formats: GeoTiff, NITF 2.0, TIFF 6.0, BIL, BIP

• off-nadir viewing: up to +26º of nadir

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TerraTerraSatelliteSatellite

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Terra satellite

• launched in December 18, 1999

• Launched as part of NASA's Earth Observing System (EOS)

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Terra

• Sensors

- ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer)

- MODIS (Moderate-resolution Imaging Spectroradiometer)

- MISR (Multi-angle Imaging Spectroradiometer)

- CERES (Clouds and the Earth's Radiant Energy System)

- MOPITT (Measurement of Pollution in the Troposphere)

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Terra/ASTER sensor

- Cooperative effort between NASA and Japan

- 14 Spectral bands

-VNIR subsystem spatial resolution: 15m. (Consisting of two telescopes - one that looks backward and the other looks nadir, it enables to produce pairs of stereo images with a base-to-height ratio of 0.6.)

- SWIR subsystem spatial resolution: 30m

-TIR subsystem spatial resolution: 90m

- swath width: 60km

- VNIR subsystem pointable up to 24 degrees, in emergency 5 days temporal resolution

-not collecting data continuously; rather, collecting an average of 8 minutes of data per orbit

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Terra/ASTER sensor

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Terra/MODIS sensor

- Cooperative effort between NASA and Japan

- 36 Spectral bands

- spatial resolution: 250m (2 bands)

500m (5 bands)

1000m (29 bands)

-Radiometric Resolution: 12 bit

- Temporal Resolution: 1-2 days

- Swath Dimension: 2330 km (cross track) by 10 km (along track at nadir)

- orbit: 705 km, 10:30 a.m. descending node (Terra) or 1:30 p.m. ascending node (Aqua), sun-synchronous, near-polar, circular

- Design Life: 6 years

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Terra/MODIS sensor

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Terra/MODIS

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LandsatLandsatSatelliteSatellite

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Landsat satellite

• The first satellite designed specifically to monitor the Earth's surface, Landsat-1, was launched by NASA in 1972

• Initial name: ERTS-1 (Earth Resources Technology Satellite)

• Commercialization year: 1985

• orbits: near-polar, sun-synchronous

• altitude and temporal resolution:

- 900 km and 18 days (Landsats 1-3)

- 700 km and 16 days (later satellites)

• equator crossing time: in the morning to optimize illumination conditions.

• Full scene dimension:185 km x 185 km

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Landsat

• Sensors

- Return Beam Vidicon (RBV) camera systems

- The MultiSpectral Scanner (MSS) systems

- 4 spectral Bands

- spatial resolution of approximately 60 x 80 metres

- radiometric resolution of 6 bits

- 6 scan lines are collected simultaneously with each west-to-east sweep of the

scanning mirror.

- The Thematic Mapper (TM)

- 7 spectral Bands

- Spatial resolution of TM is 30 m for all but the thermal infrared band which is 120 m

- radiometric resolution of 8 bits

- 16 scan lines for the non-thermal channels during both the forward (west-to-

east) and reverse (east-to-west)

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Landsat

• Sensors

- The Enhanced Thematic Mapper Plus (ETM+)

- improved version of the Thematic Mapper

- spatial resolution of 30 meters

- a new 15-meter resolution panchromatic band

- improved ground resolution for thermal infrared band (60 m vs. 120 m)

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Landsat History

• Landsat-1

- launched in 1972

• Landsat-2

- launched in 1975

• Landsat-3

- Launched in 1978

• Landsat-4

- Launched in 1982

• Landsat-5

- Launched in 1984

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Landsat History

• Landsat-6

- After launch in 1993 failed to place in orbit

- uses ETM sensor

• Landsat-7

- Launched on 15 April, 1999

- uses ETM+ sensor

-Landsat 7 orbit allow to precede the Terra satellite by 30 minutes along a common ground track

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Landsat-7 432 Multispectral image from Nosratabad, Kerman, Iran, 2002

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Mrsid (Landsat-7 742) Multispectral image from Nosratabad, Kerman, Iran, 1999-2001

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Landsat-7 PAN image from Nosratabad, Kerman, Iran, 2002

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Landsat-7 432 Multispectral image

Landsat-7 PAN image

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SPOT SPOT SatelliteSatellite

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SPOT (Système Pour l'Observation de la Terre) Satellite

• launched by CNES (Centre National d'Études Spatiales) of France, with support from Sweden and Belgium

• SPOT-1 was launched in 1986, with successors following every 3 or 4 years

• near-polar, sun-synchronous orbits

• altitude: 830 km above the Earth

• Temporal Resolution: 26 days

• equator crossing times: around 10:30 AM local solar time

• first satellite to use along-track, or pushbroom scanning technology.

• swath width: 60 km at nadir

• sensor name: HRV (high resolution visible)

• The SPOT satellites each have twin HRV imaging

systems, which can be operated independently

and simultaneously.

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SPOT (Système Pour l'Observation de la Terre) Satellite

• Spot-5 Satellite

- Launch Date: May 3, 2002

- Orbit Altitude: 822 Km

- Orbit Inclination: 98.7º, sun-synchronous

- Equator Crossing Time: 10:30 a.m. (descending node)

- Revisit Time: 2-3 days depending on Latitude

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SPOT/HRV sensor

• panchromatic (PLA) mode

- single-channel

- spatial resolution of 10 m

- swath width of 60 km at nadir

• multispectral (MLA) mode

- three multispectral bands

- spatial resolution of 20 m

- swath width of 60 km at nadir

- Each along-track scanning HRV sensor consists of 4 linear arrays of detectors:

- one 6000 element array for the panchromatic mode

- one 3000 element array for each of the three multispectral bands.

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SPOT/HRV sensor

• off-nadir viewing capability up to 27° from nadir which allows SPOT to view within a 950 km swath and to revisit any location several times per week

- improves the ability to monitor specific locations

- increases the chances of obtaining cloud free scenes

- provides the capability of acquiring imagery for stereoscopic coverage

• By pointing both HRV sensors to cover adjacent ground swaths at nadir, a swath of 117 km (3 km overlap between the two swaths) can be imaged.

• Applications of Spot in general:

• Urban mapping

• agriculture, forestry

• DEM Generation

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SPOT-5 sensor

- Spectral resolution: 4 Spectral bands

- Pan: 480 - 710 nm

- Green: 500 - 590 nm

- Red: 610 - 680 nm

- Near IR: 780 – 890 nm

- ShortWave IR: 1,580 – 1,750 nm

- Spatial resolution:

- Pan: 2.5m from 2 x 5m scenes

- Pan: 5m (nadir)

- MS: 10m (nadir)

- SWI: 20m (nadir)

- radiometric resolution: 8-bits

- Swath Width: 60 Km x 60 Km to 80 Km at nadir

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SPOT History

• Spot-1 launch date: 1986




• Spot-5 launch date: May, 2002

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IRSIRSSatelliteSatellite

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IRS (Indian Remote Sensing ) Satellite

• The third satellite in the series, IRS-1C, launched in December, 1995

• IRS-1C,1D are in orbit and IRS-P5, P6 will be launched in future

• combines features from both the Landsat MSS/TM and the SPOT HRV

• sensors:

- single-channel panchromatic (PAN) high resolution camera

- a medium resolution 4-channel Linear Imaging Self-scanning Sensor (LISS-III)

- a coarse resolution two-channel Wide Field Sensor (WiFS)

• panchromatic sensor can be steered up to 26° across-track, enabling stereoscopic imaging and increased revisit capabilities (as few as five days)

• four LISS-III multispectral bands are similar to Landsat's TM bands 1 to 4

• WiFS sensor is similar to NOAA AVHRR bands

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IRS Sensors

• radiometric resolution: 6-bits (PAN), 7-bits (LISS III & WIFS)

• swath width: 70 km

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Applications of IRS data:

• urban planning and mapping (by Pan)

• vegetation discrimination (by LISS-III)

• land-cover mapping (by LISS-III)

• natural resource planning (by LISS-III)

• regional scale vegetation monitoring (by Wifs)

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IRS History

• IRS 1a launch date: 1988

• IRS 1B launch date: 1991

• IRS 1C launch date: 1995

• IRS 1D launch date: 1997

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Marine Observation Marine Observation


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Marine Observation Satellites/SensorsMarine Observation Satellites/Sensors

The meteorological and land observations satellites/sensors we discussed in the previous two sections can be used for monitoring the oceans of the planet, but there are other satellite/sensor systems which have been designed specifically for this purpose.

Nimbus-7

• launched in 1978

• sensor name: Coastal Zone Colour Scanner (CZCS)

• intended for monitoring the Earth's oceans and water bodies

• objectives:

- observe ocean colour and temperature

- detect pollutants in the upper levels of the ocean

- determine the nature of materials suspended in the water column

• sun-synchronous, near-polar orbit at an altitude of 955 km.

• Equator crossing times were local noon for ascending passes and local midnight for descending passes

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Nimbus-7

• global coverage every six days

• spatial resolution of 825 m at nadir

• 1566 km swath width

• ceased operation in 1986

• the first four bands of the CZCS sensor which are very narrow were optimized to allow detailed discrimination of differences in water reflectance due to phytoplankton concentrations and other suspended particulates in the water.

• In addition to detecting surface vegetation on the water, band 5 was used to discriminate water from land prior to processing the other bands of information

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MOS (Marine Observation Satellite)

• launched by Japan in 1987 and was followed by MOS-1b in 1990 sensor

• intended for monitoring the Earth's oceans and water bodies

• sensors:

- a four-channel Multispectral Electronic Self-Scanning Radiometer (MESSR)

- a four-channel Visible and Thermal Infrared Radiometer (VTIR)

- a two-channel Microwave Scanning Radiometer (MSR),

• orbit at altitudes around 900 km

• revisit periods of 17 days

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MOS (Marine Observation Satellite)

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SeaStar/SeaWiFS (Sea-viewing Wide-Field-of View Sensor)

• Designed for ocean monitoring

• eight spectral bands of very narrow wavelength ranges

• objectives:

- ocean primary production and phytoplankton processes

- ocean influences on climate processes (heat storage and aerosol formation)

- monitoring of the cycles of carbon, sulfur, and nitrogen

• orbit altitude is 705 km

• local equatorial crossing time of 12 PM

• Two combinations of spatial resolution and swath width for each band:

- a higher resolution mode of 1.1 km (at nadir) over a swath of 2800 km

- a lower resolution mode of 4.5 km (at nadir) over a swath of 1500 km

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SeaStar/SeaWiFS (Sea-viewing Wide-Field-of View Sensor)

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Radar Radar


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Envisat Envisat SatelliteSatellite

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Envisat satellite

• Sponsor: European Space Agency

• Launch Date: 1 March 2002

• Orbit: circular, sun-synchronous polar

• Inclination: 98.54 degrees

• Weight: 8211 kg

• Expected Life: 5 years

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Envisat

Sensors:

- ASAR (Advanced Synthetic Aperture Radar)

- MERIS (MEdium Resolution Imaging Spectrometer Instrument)

- GOMOS (Global Ozone Monitoring by Occultation of Stars)

- AATSR (Advanced Along Track Scanning Radiometer)

- RA-2 (Radar Altimeter 2)

- SCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY)

- MIPAS (Michelson Interferometer for Passive Atmospheric Sounding)

- MWR (microwave radiometer)

- LRR (laser retroreflector)

- DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite)

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Envisat/ASAR sensor

• Polarization: HH, VV, HV or VH

• Look Direction: Right looking

• Wavelength Band: C-band

• Azimuth resolution: 4m

• Range resolution: ~20m

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ERS ERS SatelliteSatellite

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ERS-1

• European Remote Sensing satellites

• launched in July 1991

• Scene Dimension: 100Km×100Km

• The ERS-1 satellite was retired on March 10, 2000

• Altitude: 785 km

• Inclination: 98.516 degrees

• Period: About 100 minutes

• Orbit Repeat Cycle: 3, 35, or 168 days

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ERS-2

• European Remote Sensing satellites

• launched in April 1995

•The ERS-1 satellite was retired on March 10, 2000

• ERS-2 is currently about 24 hours behind ERS-1 (July, 1995)

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ERS Sensors

• AMI (Active Microwave Instrumentation)

• RA (Radar Altimeter)

• ATSR (Along Track Scanning Radiometer)

• MWS (Microwave Sounder)

• PRARE (Precise Range and Range-rate Equipment)

• LR (Laser Retroreflector)

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ERS/AMI sensor

• Polarization: VV


• Wavelength Band: C-band (5.66 cm)

• Incidence Angles, Mid: 19.35-26.50, 23 deg

• Scene Dimension: 100Km×100Km

• Transmit Frequency: 5.3 GHz

• Bandwidth: 15.55 MHz Range: 6.0

• Spatial Resolution: 12.5 m pixel spacing with 30 m resolution

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Radarsat Radarsat SatelliteSatellite

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Radarsat

• Canadian Space Agency program

• Launched on Nov. 4, 1995

• Wavelength Band: C-Band

• Repeat pass time: every 24 days.

RADARSAT can provide daily coverage of the Arctic, view any part of Canada within three days, and achieve complete coverage at equatorial latitudes every six days using a 500 kilometer wide swath.

• satellite Altitude: 798 km

• Inclination: 98.6°

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Radarsat Sensor:

- Polarization: HH


• Wavelength Band: C-band (5.66 cm)

• SAR Modes

Standard wide-Swath Fine Resolution SCANSAR Extended

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Standard Mode -7 Beams, >10% overlap- ~250km nadir offset- Swath Width: 100km - Range Resolution: 25m- Azimuth Resolution: 28m- Looks: 4- Incidence Angle Range: 20-49°

Wide Mode- 3 Beams, 10% overlap- ~250km nadir offset- Swath Width: 150km- Range Resolution: (W1) 35m, (W2) 27m, (W3) 23m- Azimuth Resolution: 28m- Looks : 4- Incidence Angle: 20-45°

Fine Resolution Mode-5 Beams, 10% overlap- ~500km nadir offset- Swath Width: 50km- Range Resolution : 8-9 m- Azimuth Resolution: 9m- Looks: 1- Incidence Angle: 35-49°

SCANSAR (Narrow) Mode- ~250km nadir offset- ~400km nadir offset- Swath Width: 300km- Range Resolution: 50 m- Azimuth Resolution: 50m- Looks: 2-4- Incidence Angle: 20-40°, 32-46°

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SCANSAR (Wide) Mode-~250km nadir offset- Swath Width: 500km , 440km- Range Resolution: 100 m- Azimuth Resolution: 100m- Looks: 4-8- Incidence Angle: 20-50°

Extended (High) Mode- 6 Beams, 3% overlap- ~500km nadir offset- Swath Width: 75km- Range Resolution: 25 m- Azimuth Resolution: 28m- Looks: 4- Incidence Angle: 50-60°

Extended (Low) Mode- ~125km nadir offset- Swath Width: 75km- Range Resolution: 25 m- Azimuth Resolution: 28m- Looks: 4- Incidence Angle: 10-20°

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SRTMSRTMmissionmission

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SRTM (Shuttle Radar Topographic Mission)

• a NASA project

• Global DEM by using 2 antennas on shuttle

• The project was an 11-day mission in February of 2000

• DEM Pixel size: 90m

• DEM accuracy: 5-6m

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other other


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Other SensorsOther Sensors Videos

• Coarser in Spatial resolution than photographs

• applications:

- Natural disaster management - crop and disease assessment

- environmental hazard control - police surveillance

Lidar (LIght Detection And Ranging)

• Active imaging technology very similar to RADAR

• Pulses of laser light are emitted from the sensor and energy reflected from a target is detected and the Time is used to measure distance

• applications:

- measuring heights of features, such as forest canopy height

- measuring depth relative to the water surface (laser profilometer)

- atmospheric studies (particle content of various layers of atmosphere)

-acquire air density readings and monitor air currents

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E) Data Reception, Transmission, and ProcessingE) Data Reception, Transmission, and Processing

Data acquired from satellite platforms need to be electronically transmitted to Earth, since the satellite continues to stay in orbit during its operational lifetime.

Three methods of data Transmission:

• Ground Receiving Station (GRS)

- is in the line of sight of the satellite (A)

• can be recorded on board the satellite (B) for transmission to a GRS later

• Tracking and Data Relay Satellite System (TDRSS) (C)

-a series of communications satellites in geosynchronous orbit

- The data are transmitted from one satellite to another until they reach the appropriate GRS

In Canada, CCRS operates two GRS:

- at Cantley, Québec (GSS)

- at Prince Albert, Saskatchewan (PASS)

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E) Data Reception, Transmission, and ProcessingE) Data Reception, Transmission, and Processing

• The data are received at the GRS in a raw digital format

• They may then be processed to correct systematic, geometric & atmospheric distortions to the imagery, and be translated into a standardized format.

• Near real-time processing systems are used to produce low resolution imagery in hard copy or soft copy (digital) format within hours of data acquisition

• Low resolution quick-look imagery is used to preview archived imagery prior to purchase.

• Quick-looks are useful for ensuring that the overall quality, coverage and cloud cover of the data is appropriate.

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Any Questions?

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ReferencesReferences

► Canada CCRS WebsiteCanada CCRS Website

►Http://www.geocities.com/bssafaee/satinfo.hHttp://www.geocities.com/bssafaee/satinfo.h

tmltml

Some Satellite Sensors’ linksSome Satellite Sensors’ links

►Http://www.geocities.com/bssafaee/links.htHttp://www.geocities.com/bssafaee/links.htmlml

Some useful links for RS & GIS & Some useful links for RS & GIS & EQEQ

Date post:	01-Nov-2014
Category:	Documents
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RS Education2

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