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MISR Data System

Processing the Data Obtained from MISR

The MISR data system

As part of NASA's Earth Observing System (EOS), data from MISR is transmitted from the Terra spacecraft to the ground, where it is handled by the EOS Data and Information System (EOSDIS). EOSDIS is an extensive ground data system set up to manage the data from all of NASA's current Earth science research satellites. It's functions include controlling the spacecraft and its instruments, processing the instrument data into products useful for scientists, distributing those products, and archiving all the data and products.

EOS instrument data received by ground stations in New Mexico, Alaska, or Norway are passed to the EOS Data and Operations Center (EDOS) at NASA's Goddard Space Flight Center in Maryland, where they are checked and divided into separate data streams, depending on the data type and destination. Science data are then forwarded to several sites across the United States, known as as Distributed Active Archive Centers (DAACs), where the data are processed into products, distributed, and archived. The DAAC that handles MISR data is within the Atmospheric Sciences Data Center (ASDC) at NASA's Langley Research Center in Virginia. The software for converting MISR data into usable science products is developed by the MISR Project staff at the Jet Propulsion Laboratory (JPL) in California and provided to the ASDC for operational use. The MISR staff at JPL work closely with the ASDC staff to ensure MISR data products are produced in the desired order and with the required quality.

In addition to the processing of MISR data, the ASDC maintains an archive of data products from a MISR airborne simulator called AirMISR. The ASDC also processes and manages the data from several other EOS instruments.

Scientists interested in obtaining MISR data products should visit the ASDC's web site,

The Earth Observing System (EOS) Data and Information System (EOSDIS) is an extensive ground data system used for NASA's current Earth science missions. This diagram depicts elements of the EOSDIS used for support of the MISR instrument.

The primary ground station for the Terra spacecraft, on which MISR flies, is at White Sands in New Mexico, to which Terra relays its data via the TDRSS communications satellite system. The TDRSS "geostationary" satellite is always directly overhead at the New Mexico ground site. There are also ground stations on the island of Svalbard, Norway, and in Alaska, that are used as a backup for the White Sands station.

The Terra spacecraft is controlled through the EOS Operations Center (EOC), located at NASA's Goddard Space Flight Center in Maryland. All of the instruments on board Terra, including MISR, are also controlled from the EOC. However, the MISR Project staff at the Jet Propulsion Laboratory (JPL) in California, where MISR was built, have an engineering and operations responsibility for MISR. That is, MISR staff must plan the operational activities for MISR, and must transmit plans and schedules to the EOC, from where MISR and the spacecraft are directly commanded. The MISR staff must also monitor the on-going status of the instrument, and investigate any instrument anomalies.

Data from MISR and from other Terra instruments is sent to the EOS Data and Operations System (EDOS), located at Goddard Space Flight Center in Maryland. Data arrives here in the form of spacecraft telemetry, and must be decoded into its component parts, checked, and then dispatched to the various data processing locations, known as Distributed Active Archive Centers (DAACs).

The DAAC where MISR data is handled is within the Atmospheric Sciences Data Center (ASDC) at NASA Langley Research Center (LaRC) in Virginia. Here the data are processed into data products of use to the scientific community, and distributed the to the end users. The data are also archived. Users who need MISR data should contact the ASDC web site, where they will find more detailed information about MISR products. From here, they contact the EOS Data Gateway (EDG), located at Goddard Space Flight Center, to place orders for products. Products are normally delivered directly over the internet or on physical media such as magnetic tape.


MISR's data products

The generation of MISR science data products can be divided into five production steps, as illustrated above. It is convenient to think of these five steps as occurring in sequence, with the predecessor producing at least one complete product, a portion of which is the primary input for the successor. These steps are grouped into three "Levels," 1, 2, and 3. Level 1 processing provides corrected (or calibrated) instrument data. Level 2 processing provides retrieval of derived scientific quantities, such as atmospheric aerosol and cloud measurements. Level 3 processing produces global maps. Here is more detail about the individual products.

Level 1 Products

These have been processed and calibrated to remove many of the instrument effects. The resulting products thus contain minimal instrument or spacecraft artifacts and are most suitable for subsequent scientific derivations.

Level 1A: Reformatted Product
The raw data from the instrument, which is intricately structured and compressed, is reformatted into more straightforward computer files. At the same time, many checks are made on the quality of the data to ensure that the instrument is working correctly.

Level 1B1: Radiometric Product
Two types of processing are included in this product. Firstly, the Radiance Scaling operation converts the camera's digital output to a measure of energy incident on the front optical surface. The measurement is expressed in units called radiance (energy per unit area, wavelength, and solid angle) as defined by the an international scale. Secondly, Radiance Conditioning modifies the radiances to remove instrument-dependent effects. Specifically, image sharpening is provided, and focal-plane scattering is removed. Additionally, all radiances are adjusted to remove slight spectral sensitivity differences among the 1504 detector elements of each spectral band and each camera.

These images of northeastern South Africa, near Kruger National Park, were acquired on September 7, 2000. The left image shows an 85-kilometer wide x 200-kilometer long area captured by MISR's aftward- viewing 45-degree camera. At lower left are the Drakensberg Mountains; to the east of this range a large burn scar with thin smoke plumes from still-smoldering fires is visible. Near the top of the image another large burn scar with an open-pit mine at its western edge can be seen. Other burn scars are scattered throughout the image.

Just above the center of the lefthand image is a polygonal burn scar with a set of smoke plumes from actively burning fires at its southwestern tip. The righthand image, which is a "zoomed-in" view of the area, was acquired almost simultaneously by MISR's airborne counterpart, AirMISR, aboard a NASA ER-2 high-altitude aircraft. AirMISR contains a single camera that rotates to different view angles; when this image was acquired the camera was pointed straight downward. Because the ER-2 aircraft flies at an altitude of 20 kilometers, whereas the Terra spacecraft orbits the Earth 700 kilometers above the ground, the AirMISR image has 35 times finer spatial resolution. The AirMISR image covers about 9 kilometers x 9 kilometers. Unlike the MISR view, the AirMISR data are in "raw" form and processing to remove radiometric and geometric distortions has not yet been performed.

Fires such as those shown in the images are deliberately set to burn off dry vegetation, and constitute a widespread agricultural practice in many parts of Africa. These MISR and AirMISR images are part of an international field, aircraft, and satellite data collection and analysis campaign known as SAFARI-2000, the Southern Africa Regional Science Intitiative. SAFARI-2000 is designed, in part, to study the effects of large-scale human activities on the regional climate, meteorology, and ecosystems.

Image Credit: NASA/GSFC/JPL, MISR and AirMISR Teams. Catalog No. PIA02624

Level 1B2: Georectified Radiance Product
The nine sets of imagery from the nine cameras are registered to one another and to the ground. This is an image processing application made necessary because the nine views of each point on the ground are not acquired simultaneously (images from cameras at the two extreme angles are 7 minutes apart.) This product is mapped into a standard map projection called Space Oblique Mercator (SOM). There is a cloud mask derived as part of the Level 1B2, called the Radiometric Camera-by-camera Cloud Mask (RCCM). (Other types of cloud mask form part of the Level 2 products.)

This is an example of the MISR Level 1B2 data product. It shows images of Delaware Bay, Chesapeake Bay, and the Appalachian Mountains acquired on March 24, 2000 during Terra orbit 1417. The large image on the right was taken by the MISR camera viewing straight down (nadir). The series of smaller images, from top to bottom, respectively, were taken by cameras viewing 70.5 degrees forward, 45.6 degrees forward, 45.6 degrees aftward, and 70.5 degrees aftward of nadir. These images cover the environs of Newark, Philadelphia, Baltimore, Washington, and Richmond. Differences in brightness, color, and contrast as a function of view angle are visible over both land and water. Scientists are using MISR data to monitor changes in clouds, Earth's surface, and pollution particles in the air, and to assess their impact on climate.

These Level 1B2 product images have all been "rectified" and "geolocated" so that they use the same map projection and scale. This allows images from the nine cameras to be superimposed or compared directly. Without this, the respective images would each have different scales and perspectives because of the differing angles of view.

Image Credit: NASA/GSFC/JPL, MISR Science Team. Catalog No. PIA02629

Austral Winter and Spring in Queensland's Brigalow Belt

Austral Winter and Spring in Queensland's Brigalow Belt

Local Mode Product
MISR is capable of taking image data in two different spatial resolution modes. In Local Mode, selected targets of 300 kilometers long are observed at the maximum resolution of 275 meters (pixel to pixel) in all cameras. Local Mode data target sites and acquisition history is available here.

Level 2 Products

These are geophysical measurements derived from the instrument data.

Level 2 Top-of-Atmosphere/Cloud Product
This contains measurements of cloud heights and winds, cloud texture, top-of-atmosphere albedos and bidirectional reflectance factors, and other related parameters. Click the image below to see what this product looks like.

The MISR team has developed new methods over the mission lifetime for retrieving information about clouds, airborne particles, and surface properties that capitalize on the instrument's unique, multi-angle imaging approach. This illustration , based upon results contained in products publicly released at the Atmospheric Sciences Data Center (ASDC), highlights some of these capabilities. The ASDC, located at NASA's Langley Research Center, is the primary processing and archive center for MISR data (

On August 21, 2000, during Terra orbit 3600, MISR imaged Hurricane Debby in the Atlantic Ocean. The first panel on the left is the MISR downward- looking (nadir) view of the storm's eastern edge. The next two panels show the results of an approach that uses MISR's stereoscopic observations to retrieve cloud heights and winds. In the middle panel of this set, gradations from low to high cloud are depicted in shades ranging from blue to red. Since it takes seven minutes for all nine MISR cameras to view any location on Earth, and the clouds moved during this time, the data also contain information about wind speed and direction. Derived wind vectors, shown in the third panel, reveal Hurricane Debby's cyclonic motion. The highest wind speed measured is nearly 100 kilometers/hour. MISR obtains this type of information on a global basis, which will help scientists study the relationship between climate change and the three-dimensional characteristics of clouds. The second and third panels are part of MISR's Level 2 top-of-atmosphere/cloud data product.

Image Credit: NASA/GSFC/JPL, MISR Team. Catalog No. PIA02629

Level 2 Aerosol/Surface Product
This products includes a range of parameters such as tropospheric aerosol optical depth; aerosol composition and size; surface directional reflectance factors and bi-hemispherical reflectance; and other related parameters. Click the image below to see an example of what this product looks like.

The MISR team has developed methods for retrieving information about clouds, airborne particles, and surface properties that capitalize on the instrument's unique, multi-angle imaging approach. This illustration, based upon results contained in products publicly available at the Atmospheric Sciences Data Center (ASDC), highlights some of these capabilities. The ASDC, located at NASA's Langley Research Center, is the primary processing and archive center for MISR data (

These data were acquired by MISR on March 6, 2000, and extend from Lake Ontario to northern Georgia in the eastern United States. The panel at left is the downward-looking (nadir) view. The center-left panel was acquired by the forward-viewing 70.5-degree camera. At this increased slant angle, the line-of-sight through the atmosphere is three times longer, and a thin haze over the Appalachians is more apparent. MISR uses this enhanced sensitivity along with the variation of brightness with angle to monitor particulate pollution and to measure haze properties. The third panel is a map of the airborne particle (aerosol) amount, and describes a quantity derived using methods that take advantage of MISR's moderately high spatial resolution at very oblique angles. The aerosol results are obtained at coarser resolution than the underlying images; gradations from blue to red indicate increasing aerosol abundance. These data indicate how airborne particles are interacting with sunlight, a measure of their impact on Earth's climate. The fourth panel shows the Earth's surface, similar to panel 1, except that the measured effects of aerosols in the atmosphere have been removed.

These data products were generated from a portion of the imagery acquired during Terra orbit 1155. The panels cover an area of about 380 kilometers x 1520 kilometers, and utilize data from blocks 54 to 65 within World Reference System-2 path 17.

Image Credit: NASA/GSFC/JPL, MISR Team. Catalog No. PIA02629

Level 3 Products

These are global maps of various parameter elements from the Level 2 products. The maps are produced monthly, seasonally (every three months), and annually. Visualization of select MISR Level 3 data is now available.

The Levels 1 and 2 products are in swaths, each derived from a single MISR orbit, where the imagery is about 400 km wide and approximately 20,000 km long.

Implementing the MISR data products

The MISR Science Team currently consists of 21 members. Some are collocated with the MISR Project at JPL, but most are located at other facilities, such as universities, both in the United States and Europe. The Science Team provides the scientific algorithms, i.e. the scientific methods, used by the MISR Project staff to implement the software used in production of data products at the ASDC. The Science Team is also responsible for validating that the products contain the correct scientific content. This validation activity is described elsewhere on this web site.

At JPL, the MISR Project Staff base their development around a computing center known as the MISR Science Computing Facility (SCF). There is a high-speed on-line connection between the SCF and the ASDC/DAAC at NASA Langley. Production at the ASDC uses several Silicon Graphics Inc. (SGI) computers with a total of approximately 128 processors. For archiving purposes, the ASDC has on-line tape libraries with a total capacity of approximately 400 Terabytes to accommodate MISR data for the duration of the Terra mission.

The release of each data product goes through four stages: Alpha, Beta, Provisional, and Validated. MISR products are first released publicly at the Beta stage, and then progress through the Provisional to the Validated stage. MISR's Beta products became available in July 2000 for Level 1 and in March 2001 for Level 2 products. The initial Level 3 Beta products will be available in late 2001. The primary Level 2 products reached the first stage of Validated status by late 2003.