The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument was first launched on the Terra satellite in December 1999. A second MODIS instrument was successfully launched with the Aqua satellite in May 2002. Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning (10:30 AM), while Aqua passes south to north over the equator in the afternoon (1:30 PM). MODIS belongs to a new generation of sensors that collect data across a wide spectral range with moderate spatial resolution (250m-1km) and near daily global coverage. MODIS images the Earth with a swath width of 2,330 km in 36 spectral bands or channels ranging in wavelength from 0.405 to 14.385 µm. It takes measurements at three spatial resolutions: 250 m, 500 m, and 1,000 m.

MODIS Spectral Characteristics
Band #	Wavelength range	Spatial resolution	Primary use
1	620 - 670 nm	250 m	Land/cloud/aerosols boundaries
2	841 - 876 nm	250 m
3	459 - 479 nm	500 m	Land/cloud/aerosols properties
4	545 - 565 nm	500 m
5	1230 - 1250 nm	500 m
6	1628 - 1652 nm	500 m
7	2105 - 2155 nm	500 m
8	405 - 420 µm	1,000 m	Ocean color/phytoplankton/biochemistry
9	438 - 448 µm	1,000 m
10	483 - 493 µm	1,000 m
11	526 - 536 µm	1,000 m
12	646 - 556 µm	1,000 m
13	662 - 672 µm	1,000 m
14	673 - 683 µm	1,000 m
15	743 - 753 µm	1,000 m
16	862 - 877 µm	1,000 m
17	890 - 920 µm	1,000 m	Atmospheric water vapor
18	931 - 941 µm	1,000 m
19	915 - 965 µm	1,000 m
20	3.660 - 3.840 µm	1,000 m	Surface/cloud temperature
21	3.929 - 3.989 µm	1,000 m
22	3.929 - 3.989 µm	1,000 m
23	4.020 - 4.080 µm	1,000 m
24	4.433 - 4.080 µm	1,000 m	Atmospheric temperature
25	4.482 - 4.549 µm	1,000 m
26	1.360 - 1.390 µm	1,000 m	Cirrus clouds/water vapor
27	6.535 - 6.895 µm	1,000 m
28	7.175 - 7.475 µm	1,000 m
29	8.400 - 8.700 µm	1,000 m	Cloud properties
30	9.580 - 9.880 µm	1,000 m	Ozone
31	10.780 - 11.280 µm	1,000 m	Surface/cloud temperature
32	11.770 - 12.270 µm	1,000 m
33	13.185 - 13.485 µm	1,000 m	Cloud top altitude
34	13.485 - 13.785 µm	1,000 m
35	13.785 - 14.085 µm	1,000 m
36	14.085 - 14.385 µm	1,000 m

(source: http://modis.gsfc.nasa.gov/about/specs.html)

Numerous MODIS data products are generated for study of land-based systems, including two vegetation indices, NDVI and the Enhanced Vegetation Index (EVI) (for more information see http://modis-land.gsfc.nasa.gov). MODIS data have been available since 2000, but the experimental nature both of the sensor and of the generation of value-added products like vegetation indices makes the data processing stream less systematic (and therefore more of a challenge to automate) than AVHRR. For purposes of the RangeView web site, the Arizona Remote Sensing Center (ARSC) obtains MODIS data and value-added products through the EOSDIS Distributed Active Archive Centers (DAACs) and their recently instituted Data Pools. The data are made available in 1200 by 1200 km tiles that cover the globe; however, RangeView is currently focusing on the six tiles which cover the southwestern U.S. and northern Mexico. Though processed differently than AVHRR data, many of the MODIS products are composited images with one image representing the entire composite period (8 and 16 days). The products currently in use or proposed for future use in RangeView, their corresponding composite periods, spatial resolutions, and geographic coverage areas are listed below.

Some MODIS Land Products
Modis product	Composite period	Spatial resolution	Coverage area
Vegetation indices (NDVI, EVI)	16-day	1,000 m	Southwest US & northern Mexico
Vegetation indices (NDVI, EVI)	16-day	250 m	Arizona
Land cover/Land* Cover Change	96-day	1,000 m	Southwest US & northern Mexico
Thermal anomalies, fires, biomass burning*	8-day	1,000 m	Southwest US & northern Mexico
Leaf Area Index (LAI) and FPAR*	8-day	1,000 m	Southwest US & northern Mexico
Net photosynthesis and Primary Productivity*	8-day	1,000 m	Southwest US & northern Mexico
*Proposed for RangeView in the future

The Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI; a vegetation index tailored to maximize MODIS spectral capabilities) are the principal products currently used in this project. In addition to the vegetation indices acquired from EOS, ARSC produces several products from the NDVI and EVI data using in-house image processing protocols. These include difference from previous period and difference from previous year for both NDVI and EVI. ARSC is also actively pursuing data continuity research in an attempt to make the most of the long-term nature of the AVHRR data set relative to MODIS products.

MODIS data may be ordered through the EROS Data Center's Earth Observing System Data Gateway at http://edcimswww.cr.usgs.gov/pub/imswelcome/.
See
MODIS Web (http://modis.gsfc.nasa.gov/),
TERRA (http://terra.nasa.gov/), or
AQUA (http://aqua.gsfc.nasa.gov/)
for more information.

Sidebar material adapted from the RangeView Glossary (http://rangeview.arizona.edu/glossary/glossary.html/)

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