Sinusoidal Tile Grid

Most standard MODIS Land products use this Sinusoidal grid tiling system. Tiles are 10 degrees by 10 degrees at the equator. The tile coordinate system starts at (0,0) (horizontal tile number, vertical tile number) in the upper left corner and proceeds right (horizontal) and downward (vertical). The tile in the bottom right corner is (h35,v17).

Climate Modeling Grid

The Climate Modeling Grid (CMG) products provide global coverage in a Geographic Latitude and Longitude projection at a resolution of 0.05 degrees (5,600 meters at the equator). The geographic coordinates of the upper-left corner of the upper-left pixel of a MODIS CMG image are -180.00 degrees longitude, 90.00 degrees latitude. The geographic coordinates of the lower-right corner of the lower right pixel are 180.00 degrees longitude, -90.00 degrees latitude.

MODIS Processing Levels

NASA distributes MODIS Land data processed to Level 2 or higher.

MODIS Processing Description

Along with all the data from other instruments on board the Terra and Aqua platforms, MODIS data are transferred to ground stations in White Sands, New Mexico, via the Tracking and Data Relay Satellite System (TDRSS). The data are then sent to the EOS Data and Operations System (EDOS) at the Goddard Space Flight Center. After Level 0 processing at EDOS, the Goddard Earth Sciences Data and Information Services Center (GES DISC) produces the Level 1A, Level 1B, geolocation, and cloud mask products.

Higher-level MODIS land and atmosphere products are produced by the MODIS Adaptive Processing System (MODAPS), and then are parceled out among three DAACs for distribution. Ocean color products are produced by the Ocean Color Data Processing System (OCDPS) and distributed to the science and applications community.

MODIS products have two sources of metadata: the embedded HDF metadata, and the external ECS metadata. The HDF metadata contains valuable information including global attributes and dataset specific attributes pertaining to the granule. The structure of this metadata is broadly similar to that of an ASTER HDF file. The ECS (generated by the EOSDIS Core System) .met file is the external metadata file in XML format, which is delivered to the user along with the MODIS product. It provides a subset of the HDF metadata. Some key features of certain MODIS metadata attributes include the following:

• The Xdim and Ydim represent the rows and columns of the data, respectively.
• The Projection and ProjParams identify the projection and its corresponding projection parameters.
• The Sinusoidal Projection is used for most of the gridded MODIS land products, and has a unique sphere measuring 6371007.181 meters.
• The UpperLeftPointMtrs is in projection coordinates, and identifies the very upper left corner of the upper left pixel of the image data.
• The LowerRightMtrs identifies the very lower right corner of the lower right pixel of the image data. These projection coordinates are the only metadata that accurately reflect the extreme corners of the gridded image.
• There are additional BOUNDINGRECTANGLE and GRINGPOINT fields within the metadata, which represent the latitude and longitude coordinates of the geographic tile corresponding to the data.

The dataset attributes contain specific SDS information such as the data range and applicable scaling factors for the data. The LP DAAC data products page provides these details within a concise document for each of the products. An HDF-EOS file also contains EOS core metadata essential for EOS search services. Any tool that processes standard HDF files can read an HDF-EOS file. However, it is difficult for a standard HDF call to interpret HDF-EOS geolocation or temporal information without further knowledge of the file structure.

Early in the mission, the MODIS Science Team decided to maintain a record of multiple data versions of Aqua- and Terra-derived MODIS products from a unique temporal bracket. Called the “Golden Month,” it covers 40 days of acquired data and all derived products from August 29, 2002 to October 7, 2002 (2002-241 to 2002-280). Several reasons define this choice of acquisition window, which include the following:

• This acquisition window provides the first interval when both Terra and Aqua MODIS data were collected uninterrupted.
• Previous (V003, V004, V005, and V006) and subsequent (V061) data versions are available.
• It avoids the end of July 2002 Aqua safe-hold incident.
• It includes the end of the Northern Hemisphere growing season.
• The period contains the fall equinox, which ensures that both hemispheres are illuminated.
• It includes two full 16-day periods (2002-241 to 2002-272).
• It includes all 8-day periods overlapping September 2002.