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Congo Basin Satellite Imagery Resources

The following is a list of the major sources of satellite data available for the Congo Basin. Information is provided regarding satellite payloads, sensor characteristics, spectral resolution, spatial resolution, swath dimensions, and temporal coverage. Additionally we have supplementary links providing more details on these systems, plus several locations where the data can be accessed or ordered. Information on each data site is provided to further assist users in expediting their data queries and requests. When possible we have collected links that can help guide the user on the use of the particular imagery in areas such as band combinations or suitable applications for the imagery.

A general introduction to remote sensing with satellite imagery for beginners can be found at the NASA Remote Sensing Tutorial.







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Landsat


Landsat 5 scene from within the DRC

The Landsat program offers the longest continuous global record of land cover images beginning in 1972 with Landsat 1. The first five Landsats carried the Multispectral Scanner System (MSS) sensor that had a spatial resolution of 68 m by 83 m and contained four bands, while Landsat 3 contained an additional thermal band. Then beginning in 1982, Landsat 4 and later Landsat 5 both carried the Thematic Mapper (TM), which has seven bands at a 30 m spatial resolution except the thermal band that has a 120 m spatial resolution. Landsat 6 failed to achieve orbit and was lost. Landsat 7 was launched in 1999 and contained the Enhanced Thematic Mapper Plus (ETM+), which is an improved version of the TM sensor. The ETM+'s thermal band has an improved spatial resolution of 60 m compared to the TM's 120 m spatial resolution. In addition the ETM+ also contains a 15 m panchromatic band. Landsat 1-3 had repeat coverage every 18 days and Landsat 4, 5, and 7 repeat their coverage every 16 days.

Landsat 5 was operational for 29 years, while its original mission was meant to last only for 3 years. The failure of a gyroscope in 2012 left no option but to shut down the satellite in June 2013. Landsat 7 is still operational. However, Landsat 7 has suffered a failure of its Scan Line Corrector (SLC) assembly, which controls the cross track motion of the scan mirror. The Landsat 7 ETM+ images still acquire about 75% of the data for each scene with wedge shaped gaps along the edges of the scenes.

The continuous global record, medium spatial resolution, and the opening up of the Landsat archives to the public in 2008 has made this dataset one of the most prevalent in earth system studies. NASA successfully launched the Landsat Data Continuity Mission on February 11, 2013. The satellite was renamed Landsat 8 and operation has been transferred to the USGS. Data collected since April 11, 2013 by the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) on board Landsat 8 are available for download.

  • Further Information:
    NASA Landsat Program
    NASA Landsat Data Continuity Mission

  • Helpful Data Tools:
    Band Designations for Landsat Satellites
    Band Information and Useful Combinations
    Useful Landsat Band Combinations

  • Data Acquisition links:
    USGS Global Visualization Viewer FREE

    USGS EarthExplorer FREE

    ECHO's Reverb Client FREE

    USGS LandsatLook Viewer FREE

    OSFAC Satellite Data and Products


Sensor Bands Spatial Resolution Swath Width Spectral Range Temporal
Coverage
MSS 4 bands 68 m x 83 m 185 km x 185 km Green, Red, Near-IR,
Thermal-IR
18 days
TM 7 bands 30 m, (120 m - thermal) 183 km x 172 km Blue, Green, Red,
Near-IR, Mid-IR,
Thermal-IR, Mid-IR2
16 days
ETM+ 8 bands 30 m
(60 m - thermal, 15 m pan)
183 km x 170 km Blue, Green, Red,
Near-IR, Mid-IR,
Thermal-IR, SWIR,
Panchromatic
16 days
OLI &
TIRS
11 bands 30 m
(100 m - thermal, 15 m pan)
183 km x 170 km Coastal aerosol, Blue, Green,
Red, Near-IR, SWIR-1, SWIR-2,
Panchromatic, Cirrus,
Thermal-IR 1, Thermal-IR 2
16 days


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MODIS


MODIS, south eastern DRC.
Detected fires and borders are highlighted.

Source:
NASA LANCE Rapid Response

MODIS stands for MODerate Resolution Imaging Spectroradiometer. MODIS instruments are a part of the payloads on board NASA's Earth Observing System (EOS) Terra (EOS AM) and Aqua (EOS PM) satellites. Terra (EOS AM) was launched December 1999 and Aqua (EOS PM) was launched May 2002. The orbit of Terra goes from north to south across the equator in the morning and Aqua passes south to north over the equator in the afternoon, resulting in global coverage every 1 to 2 days with ground track repeat cycles every 16 days. The spatial resolution varies depending on the bands: 250 m, 500 m, or 1000 m.

MODIS is notable for being the first satellite imagery that was designed to be freely available to the public from the very beginning. Additionally, from the start MODIS has offered a number of useful data products such as: burned area, surface reflectance, vegetation indices, land surface temperature & emissivity, thermal anomalies & fire, leaf area index, gross primary productivity, albedo, land cover type, and many more. These data products are then distributed based on daily data or from temporal composites based on 8 days, 16 days, 32 days, or yearly observations.

  • Further Information:
    NASA MODIS Web

  • Helpful Data Tools:
    Band Information and Useful Combinations

  • Data Acquisition links:
    USGS Global Visualization Viewer FREE

    USGS EarthExplorer FREE

    NASA's LAADS Web FREE

    ECHO's Reverb Client FREE

    NASA LANCE Imagery FREE


Bands Spatial Resolution Swath Width Spectral Range Temporal
Coverage
36 bands Near-IR and Red (250 m),
Blue, Green, and 3 IR bands (500 m),
bands 9-36 (1000 m)
2330 km MODIS specifications 1-2 days revist,
ground track repeat cycle
every 16 days


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ASTER


ASTER image of the White Nile, 39.1 x 40.5 km

Source:
NASA/GSFC/METI/ERSDAC/JAROS,
and U.S./Japan ASTER Science Team

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an imaging instrument on the Earth Observing System (EOS) Terra, which was launched in 1999. ASTER is a cooperative effort between NASA, Japan's Ministry of Economy, Trade and Industry (METI) and Japan's Earth Remote Sensing Data Analysis Center (ERSDAC).

ASTER consists of three subsystems: the Visible and Near Infrared (VNIR), the Shortwave Infrared (SWIR), and the Thermal Infrared (TIR). The VNIR subsystem operates in three spectral bands at the visible and near-IR wavelengths, with a spatial resolution of 15 m. It consists of two telescopes, one nadir looking with a three spectral band detector, and the other is a backward looking with a single band detector. The backward looking telescope provides a second view of the target area in Band 3 for stereo observations. The SWIR subsystem operates in six spectral bands in the near-IR region through a single, nadir-pointing telescope that provides a 30 m spatial resolution. The TIR subsystem operates in five bands in the thermal infrared region using a single, fixed-position, nadir-looking telescope with a spatial resolution of 90 m. ASTER is currently only available for free within the U.S. and its territories, except for NASA-supported researchers and their affiliates, as well as approved educational users.

  • Further Information:
    NASA ASTER Site
    NASA-Land Process Distributed Active Archive Center (LP DAAC)

  • Helpful Data Tools:
    Band Information and Useful Combinations

  • Data Acquisition links:
    USGS Global Visualization Viewer $$$

    USGS EarthExplorer $$$

    ECHO's Reverb Client $$$

    OSFAC Satellite Data and Products


Subsystem Bands Spatial Resolution Swath Width Spectral Range Temporal
Coverage
VNIR 3-Nadir bands,
1-Backward looking
15 m 60 km Band 1: 0.52-0.60 um
Band 2: 0.63-0.69 um
Band 3: 0.76-0.86 um
Band 3B: 0.76-0.86 um
16 days
SWIR 6 bands 30 m 60 km Band 4: 1.600-1.700 um
Band 5: 2.145-2.185 um
Band 6: 2.185-2.225 um
Band 7: 2.235-2.285 um
Band 8: 2.295-2.365 um
Band 9: 2.360-2.430 um
16 days
TIR 5 bands 90 m 60 km Band 10: 8.125-8.475 um
Band 11: 8.475-8.825 um
Band 12: 8.925-9.275 um
Band 13: 10.25-10.95 um
Band 14: 10.95-11.65 um
16 days


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SPOT


SPOT-5 HRG at 10m spatial resolution within the central
Democratic Republic of Congo

The Satellites Pour l'Observation de la Terre or Earth-observing Satellites (SPOT) remote-sensing program was set up in 1978 by France along with Belgium and Sweden. In 1986 SPOT 1 was launched with two Visible High-Resolution (VHR) optical instruments onboard. VHR contains three spectral bands (Green, Red, Near-IR) at a 20 m spatial resolution and a panchromatic band at a 10 m spatial resolution. SPOT 2 and 3 launched in 1990 and 1993 respectively, also contained the same payload of two VHR sensors.

SPOT 4, launched in 1998 contains two Visible & Infrared High-Resolution (HRVIR) sensor and the first VEGETATION sensor. The HRVIR is a more advanced version of the VHR that has four spectral bands (Green, Red, Near-IR, and Mid-IR) that operates in multispectral mode with a 20 m spatial resolution. In addition, it can operate in monospectral mode that gives band 2 (Red) a 10 meter spatial resolution. The VEGETATION sensor provides near daily global coverage at a 1 km spatial resolution. VEGETATION is a wide-angle radiometric camera operating in four spectral bands (Blue, Red, Near-IR, and Mid-IR).

SPOT 5, launched in 2002, has several sensors on its payload: two High Resolution Geometric (HRG) sensors, a High Resolution Stereoscopic (HRS) sensor, and a VEGETATION sensor. The HRG is a higher resolution continuation of the HRVIR sensor, providing three bands (Green, Red, Near-IR) at a 10 m spatial resolution, SWIR at a 20 m resolution, and a panchromatic band at 5 m or 2.5 m spatial resolution. The HRG sensor on SPOT 5 returned to the full panchromatic band from earlier satellites (SPOT-1-2-3) to ensure a continuity of spectral coverage from the very beginning of the SPOT program. The HRS sensor acquires stereopair images at a 10m spatial resolution for the creation of quality digital elevation models (DEM).

  • Further Information:
    SPOT IMAGE

  • Data Acquisition links:
    Free VEGETATION Products FREE

    Fee-Based VEGETATION Products $$$

    SPOT Imagery Catalog $$$

    Planet Action Imagery Grants Grants

    Portail de l'observation spatiale des forêts du bassin du Congo Grants

    CARPE Partners, email CARPE for data inquiries

Sensor Bands Spatial Resolution Swath
Dimensions
Spectral Range Temporal
Coverage
HRV 4 bands Multispectral (20 m),
Panchromatic (10 m)
60 x 60 km Green, Red,
Near-IR,
Panchromatic
26 days nadir,
4-5 days revisit
HRVIR 5 bands Multispectral (20 m),
Monospectral (10 m)
60 x 60-80 km Green, Red,
Near-IR, SWIR,
Monospectral
26 days nadir,
4-5 days revisit
VEGETATION 4 bands 1 km 2,250 km Blue,Red,
Near-IR, SWIR
1 days
HRG 5 bands VIS + Near-IR (10 m),
SWIR (20 m),
Pan (5 m or 2.5 m)
60 x 60-80 km Green, Red,
Near-IR, SWIR,
Panchromatic
26 days nadir,
4-5 days revisit
HRS Single band
(Stereopair images)
10 m 120 km Panchromatic 26 days


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CBERS


CBERS-2B, Sensor: CCD.
Aripuanã region, in Mato Grosso, has presented
with deforestation. The red areas are exposed soil
and regular shapes indicate deforested area.

Source:
CBERS/INPE

The China-Brazil Earth Resources Satellite (CBERS) program was born from a partnership between Brazil and China in 1988. The CBERS program initially developed two remote sensing satellites CBERS-1 and 2, which are identical in their technical structure, space mission and payload. CBERS-1 was launched in 1999 and operated until August 2003. CBERS-2 was launched in October of 2003 and is currently in operation. Their payloads consists of three different sensors: the High Resolution CCD Camera (HRCCD), the Infrared Multispectral Scanner (IRMSS), and the Wide-Field Imager (WFI).

In 2007 CBERS-2B was launched to ensure data continuity between earlier CBERS systems and the more advanced CBERS 3 + 4 to be launched later. CBERS-2B contains the HRCCD and the WFI sensors. However, a new High Resolution Panchromatic Camera (HRC) replaces the IRMSS. China and Brazil have signed agreements to continue the CBERS program with upgraded sensors in CBERS-3 and CBERS-4. CBERS-3 and CBERS-4 are expected to launch in 2012 and 2013 respectively.

  • Further Information:
    CBERS INPE

  • Data Acquisition links:
    INPE Image Catalog FREE


Sensor Bands Spatial
Resolution
Swath Width Spectral Range Temporal
Coverage
HRCCD 5 bands 20 m 113 km Blue, Green,
Red, Near-IR,
Panchromatic
26 days nadir,
3 days revisit
IRMSS 4 bands 80 m
(160 m thermal)
120 km VIS, Near-IR,
Short wave-IR,
Thermal-IR
26 days
WFI 2 bands 260 m 885 km Red, Infrared 5 days
HRC Single band 2.7 m 27 km Panchromatic 130 days


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Very High Resolution


A panchromatic Quickbird-2 image from within the DRC.
Individual trees and other features are clearly observable.




A multispectral Ikonos image from northeastern Rwanda.
Farm fields can be seen along the edge of the Volcanoes
National Park.




A multispectral WorldView-2 image from within the DRC.




A multispectral GeoEye-1 image from the eastern DRC.

High Resolution optical satellite imagery is generally considered to have a spatial resolution of 10m or less per pixel. This category includes SPOT, Quickbird 2, Ikonos, Worldview 1 + 2, GeoEye 1/Orbview 5, and RapidEye. High resolution satellites are relatively new in satellite remote sensing and their archives are generally limited to the last decade. The majority of satellites within this category are commercially owned and operated and as such, access requires payments in most cases. However, there are some non-profit organizations that can help to supplement the purchasing of these images.

  • Quickbird 2

  • Quickbird-2 was launched in October of 2001 and is owned by DigitalGlobe, a major supplier of satellite and aerial imagery. QuickBird-2 collects both panchromatic and multispectral data, with a resolution of 0.65 meter at nadir for the panchromatic band, and 2.62 meter at nadir for the multispectral bands. The revisit time for Quickbird-2 is currently 2.5 days or less at nadir and 5.6 days at 20 degrees off-nadir.


  • IKONOS

  • IKONOS was launched in September 1999 and is owned and operated by GeoEye, Inc. It was one of the first commercial satellites that was able to provide panchromatic images at spatial resolutions bellow 1 meter. IKONOS's sensor system provides panchromatic data at 0.82 m at nadir and 1 .0 m at 26 degrees off nadir. The multispectral bands (blue, green, red, and near-IR) are collected at 3.2 m at nadir and 4.0 m at 26 degrees off nadir. IKONOS also has the ability to acquire stereo satellite imagery for the use in Digital Elevation models (DEMs) or Digital Surface Models (DSMs). The revisit time for IKONOS is approximately every 3 days.


  • Worldview 1 + 2

  • World View-1 was launched in September 2007 and is owned by DigitalGlobe. It is a panchromatic imaging system with 0.5 m resolution at nadir and 0.55 m off-nadir. It also features a revisit time of 5.4 days for 20 degrees off nadir with 0.55 m resolution or a 1.7 day revisit time with a 1 m resolution.

    WorldView-2 was launched in October 2009 and contains both a panchromatic band and eight multispectral bands operating at high resolution. The panchromatic imaging system has a 0.46 m resolution at nadir and 0.52 m off-nadir. The multispectral imaging system has a 1.85 m resolution at nadir and 2.07 m off-nadir. The 8 band multispectral system includes the standard four bands (blue, green, red, and near-IR) plus 4 additional bands (coastal, yellow, red edge, and near-IR2) for additional analysis support.


  • GeoEye 1/Orbview 5

  • GeoEye-1, previously known as Orbview-5, was launched in September 2008 and is currently owned and operated by GeoEye, Inc. The sensor system includes a panchromatic band with a 0.41 m resolution at nadir and four multispectral bands (blue, green, red, and near-IR) with a 1.65 m resolution at nadir. Revisit time varies between 2.1 days at 35 degrees off nadir to 8.3 days at 10 degrees off nadir.


  • RapidEye

  • RapidEye is a constellation of five identical satellites that are owned and operated by RapidEye AG, a German geospatial information provider. The satellites all have a multispectral imager that collects data in the blue, green, red, red-edge, and near-IR portions of the electromagnetic spectrum. The imager has a ground sample size of 6.5 m that is orthorectifed to give a 5 m pixel size. By having a constellation of 5 satellites RapidEye is able to provide a revisit time of daily when off-nadir and a nadir revisit time of 5.5 days.



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Radar


A wide-swath Advanced Synthetic Aperture Radar (ASAR)
image of the Congo River in the eastern DRC.

Source:
Earth Snapshot

Radar is an active remote sensing system that utilizes the microwave/radio portion of the EM spectrum and can be used throughout all weather conditions and during night or day. One of the most common types of radar instruments is the Synthetic Aperture Radar (SAR). Over the years there have been a number of satellites with radar systems which include, but are not limited to: SIR-(A, B, C), RADARSAT-1-2, ERS-1-2, JERS-1, SEASat and ENVISAT. The radar ranging system works by emitting a pulse towards the target and then using an antenna to receive and record the round trip time and strength of the resulting backscatter. Backscatter will vary depending the target's electrical and water content properties, plus backscattering will change based on the use of different polarizations.

Some SARs can transmit pulses in either horizontal (H) or vertical (V) polarization and receive in either H or V, with the resultant combinations of HH (Horizontal transmit, Horizontal receive), VV, HV, or VH. Low-frequency SARs may be used under certain conditions to penetrate foliage and even soil. This provides the capability for imaging targets normally hidden by trees, brush, and other ground cover. To obtain adequate foliage and soil penetration, SARs operate at relatively low frequencies (10's of MHz to 1 GHz).

Another type of radar is the Phased Array type L-band Synthetic Aperture Radar (PALSAR). PALSAR uses the L-band frequency range (1.27 GHz), which allows it to cover a wider swaths of area compared to normal SAR sensors. Most notably this sensor was carried onboard the Japan Aerospace Exploration Agency (JAXA) Daichi - Advanced Land Observing Satellite (ALOS). The PALSAR sensor on board ALOS had a spatial resolution ranging from 10 to 100 meters depending on the observation mode and viewing angle. ALOS operated from January 2006 until it completed its mission in May 2011. A follow on mission, ALOS-2, is planned with a possible launch in 2013 in order to continue the radar component of ALOS.

  • Further Information:
    Sandia National Laboratories: What is SAR?
    JAXA about ALOS
    Radar Polarimetry

  • Helpful Data Tools:
    Tutorial in Radar Remote Sensing

  • Data Acquisition links:
    ASF DAAC SAR Data Archive $$$

    JAXA EORC Data Distribution Service $$$/FREE

    TerraSAR-X/TanDEM-X Ordering $$$

    OSFAC Satellite Data and Products



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LiDAR


A section of a LiDAR image of a forest near Rotorua,
the profile of nine seperate trees are clearly shown.

Source:
New Zealand Ministry for the Environment

Light Detection And Ranging (LiDAR) is an active optical remote sensing technology that discharges tens of thousands of infrared pulses a second from a laser, in order to determine elevation values based on the measured travel times of pulses. Combined with a Global Positioning System (GPS) and a gyroscope, LiDAR is able to collect highly accurate elevation values with high positional accuracy. LiDAR is typically collected from planes and because it is an active sensor providing its own energy source, it can be flown day or night. However, unlike radar, LiDAR cannot penetrate clouds, rain, or dense haze and therefore is only flown during periods of fair weather.

For terrestrial and topographical applications LiDAR typically use three different systems: Single return LiDAR, Multiple returns LiDAR, and Waveform LiDAR. Single return LiDAR records just a single return per pulse, which maps only the top of the vegetation canopy or the ground surface from any of the pulses that penetrated through holes in the vegetation canopy. Multiple return LiDAR records up to five return signals per individual laser pulse, allowing the system to record more information about the three dimensional surface environment. The first return provides the canopy height measurement, the last return provides the actual ground measurement, and the intermediate returns provide information on vegetation canopy and understory structure. Waveform LiDAR records the entire return waveform from each laser pulse. These systems are similar to the multiple returns LiDAR in their uses, but they record significantly more information on the canopy and understory structure. Waveform and Multiple return systems are especially helpful for determining forest structure and biomass levels.

Currently one of the only satellite based LiDAR systems is from ICESat (2003-2009) using the GLAS (the Geoscience Laser Altimeter System), which was the first LiDAR instrument for continuous global observations. ICESAT-2, scheduled for launch in 2016 will have an updated sensor system with an along track sampling density of about 70 cm.

  • Further Information:
    USGS center for LiDAR
    NSIDC ICESat/GLAS Data Summaries

  • Data Acquisition links:
    NSIDC DAAC ICESat/GLAS Data FREE

    ECHO's Reverb Client FREE