MISR
AVAILABILITY
http://www-misr.jpl.nasa.gov/mission/faq.html The MISR Science Team currently consists of 17 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.
REQUEST PROCEDURE
http://www-misr.jpl.nasa.gov/mission/data/getdata.html How to order MISR data: The ASDC's MISR Data Sets page (the central location indicated at the top of this page) contains a range of useful links, under the "Data" heading. This includes a Workshop Presentation that gives many details about product ordering. There are low-resolution browse images to assist in selecting products to order. See the Browse Tool on the ASDC's MISR Data Sets page. MISR's Level 1 and Level 2 data products are produced as full-swath (orbit) granules, which are large. If you need only a small segment of a swath, you can take advantage of the MISR order and customization tool. The MISR order and customization tool also includes a reformatting feature, which allows delivery of products in conventional HDF-EOS format, rather than MISR's special stacked-block format. Obtaining data through the data pool: The data pool is an on-line cache of short-term data products downloadable via FTP from the ASDC. See the ASDC's Data Pool page. MISR data specially produced or assembled for fast delivery during field campaigns is also available through the data pool, and can be accessed at the ASDC's MISR Data sets page. Currently available data products: These are listed on the ASDC's MISR Data Sets page. To help in the understanding of MISR's Level 3 global products, an overview of Level 3 imagery is accessible on the ASDC's MISR Data Sets page. Structure and content of MISR data products, and which files you need to order: There is a Project Guide on the ASDC's MISR Data Sets page that provides a top-level introductory description of the products and what to order. MISR's Algorithm Theoretical Basis (ATB) documents are on line at the EOS Project Science Office at NASA Goddard Space Flight Center. MISR's product maturity levels (Alpha, Beta, Provisional, Validated) are described in a separate page.
Satellite Instruments
Multi-angle Imaging SpectraRadiometer MISR is a new type of instrument, designed to address this issue; it views Earth with cameras pointed in 9 different directions [see illustration]. As the instrument flies overhead, each piece of Earth's surface below is successively imaged by all 9 cameras, in each of 4 wavelengths (blue, green, red, and near-infrared). To accomplish its scientific objectives, the MISR instrument measures Earth's brightness in 4 spectral bands, at each of 9 look angles spread out in the forward and aft directions along the flight path. Spatial samples are acquired every 275 meters. Over a period of 7 minutes, a 360 km wide swath of Earth comes into view at all 9 angles. Special attention has been paid to providing highly accurate absolute and relative calibration, using on-board hardware consisting of deployable solar diffuser plates and several types of photodiodes. Global coverage with MISR is acquired about once every 9 days at the equator; the nominal lifetime of the mission is 6 years. MISR was built for NASA by the Jet Propulsion Laboratory in Pasadena, California, and is one of five instruments launched into polar orbit aboard NASA's Terra spacecraft in August 1999. The spacecraft flys in a "sun-synchronous" orbit, designed so that it crosses the equator every 98 minutes, always at 10:30 a.m. local time, as Earth rotates below.
SPECIFICATIONS
Measurment TypeVisible/IR-imager
Platform TypeEOS Terra
OrbitSun synchronous
Spectral CoverageVis
Active/PassivePassive
Scan PatternMulti-angle
Variablesaerosols, BRDF, ocean color, cloud properties
Altitude
Inclination
Repeat Timebetween 2 and 9 days depending on latitude
Wavelength0.4 to 1.0um
Number of Bands4
Start DateAug 1999
Temporal Coverage6 years of life planned
Swath Width360
REFERENCES
http://www-misr.jpl.nasa.gov/mission/pub.html
REMARKS
spatial resolution is dependent upon the multi-angled camera, not so much as dependent upon the spectral band. range is 250 to 1km. Since many physical phenomena, such as the lateral diffusion of radiation within aerosol layers, have characteristic horizontal scales on the order of 1 km, sub-kilometer resolution is required to resolve these scales. The intrinsic crosstrack dimensions of the MISR pixels was therefore chosen to be 275 meters at all off-nadir angles. For reasons of economy, the nadir camera makes use of the A camera design, resulting in a slightly higher crosstrack resolution of 250 meters, and this allows it to provide a slightly better ground locating reference that is passed on to the observations from the other cameras. The time between acquisition of successive lines of MISR data (the line repeat time) is the same for all cameras, with an average of 275 meters of downtrack displacement. For the 705 km orbit, this requires a repeat time of 40.8 milliseconds. In addition to the nadir, the cameras will image Earth at 26.1, 45.6, 60.0, and 70.5 degrees forward and aftward of the local vertical. The fore and aft camera angles are the same, i.e. the cameras are arranged symmetrically about the nadir.
UPDATED ON
3 Sep 2009 13:47