Last Update: December 23, 2010
The purpose of this page is to provide users of the MODAPS/LAADS with a
variety of basic information concerning the MODIS instrument, the MODIS
products, and the services available from MODAPS for the acquisition of
MODIS products and production codes. As noted on the home page, the
transition of the GES DAAC MODIS production and distribution functionality
to MODAPS results in the fact that the MODAPS services will change over the
period from the present through September 2006. At the end of the
transition MODAPS will be the location for all production of MODIS
atmospheres and L1 data products, and all archive and distribution of MODIS
L0, Collection 4 and 5 atmospheres, and L1 data products.
Details of the transition are provided at
Transition Issues and
The MODIS Instrument
Details concerning the Aqua and Terra MODIS instruments are available at
MODIS Technical Specifications
(this link will open in a new browser window).
Using the MODIS Data products
Information concerning the MODIS data products and their use is available at
Terra Product Descriptions
Aqua Product Descriptions
Improvements from Collection 4 to Collection 5
The development of the Collection 5 L1 and atmospheres codes from their
predecessor Collection 4 codes has been a 2-year development and test
process. The changes and improvements incorporated into the Collection 5
codes are quite considerable. Improvements in the L1 and cloud mask codes
are identified in
MODIS Collection 5 Improvements Summary and
improvements in the atmospheres codes are discussed in
MODIS Atmospheres Collection 5 Update
(this link will open in a new browser window).
The MODIS Vocabulary
As any complex science instrument and data system, MODIS utilizes and has
developed its own special vocabulary. Explanations of the terminology used
throughout this web site are given in
The MODAPS generates Aqua and Terra L1, atmospheres, and land data products
on a near-real time basis using L0, ancillary, and ephemeris and attitude
data products obtained from the GES DAAC. On this web site, this is
referenced as forward processing. Because of latency in the supply of data
products from the ancillary data providers, MODAPS is able to generate
forward processed L1 and L2 atmospheres products approximately 24 hours
behind real time. In August 2006, MODAPS will interface directly with EDOS
and will obtain L0 data from this source rather than the GES DAAC.
At the present time MODAPS generates forward-processed Collection 4 L1 and
land products and Collection 5 L1 and atmospheres products for Aqua and
Terra. The land Science Team is still science testing the Aqua algorithms
and the Collection 4 land processing will not be converted to Collection 5
until this is completed. It is expected that this science testing will
continue until late December 2006 and the Collection 5 conversion will be
made on dataday January 1, 2007.
As new Collections of atmospheres and land codes become available, MODAPS
reprocesses all L1 and L2+ data products from first light of Terra and Aqua
to the present time. Terra first light occurred on February 24, 2000 and
Aqua first light occurred on July 4, 2002. For the past 2 years the
Principal Investigators have been developing the Collection 5 science codes.
Development of the Collection 5 atmospheres Aqua and Terra codes and the
land Terra codes has been completed. The Collection 5 land Aqua codes will
be available in late December, 2006. The Collection 5 reprocessing will involve
the generation of approximately 10 years of data products. The reprocessing
schedule is as follows:
The Collection 5 Aqua atmospheres reprocessing stared in early April 2006
and was completed in mid-July.
The Collection 5 Terra atmospheres reprocessing was started in mid-July
and will be completed in mid-December, 2006. The reprocessing is being
performed out of time order in order to provide end-user continuity as the
GES DAAC functionality transfers to MODAPS. The reprocessing is being
performed at 15 datadays/day (referenced as 15x).
The Collection 5 Terra land reprocessing started in mid-July and started
at first light. The reprocessing will proceed at approximately 3.5x and
the Terra-only interval (i.e. through dataday July 4, 2002) will be
completed by late-February 2007. Thereafter, Aqua and Terra will be
reprocessed in parallel to expedite the generation of the land combined
products (i.e. those products requiring both Terra and Aqua data). The
land reprocessing will be completed by late April 2008.
Additional details of the MODAPS data production (planned and actual
production, ingest metrics, versions of science codes used in production,
etc.) are given at
Production and details of the
reprocessing plans are provided at
Collection 5 Atmospheres Reprocessing Plan
Collection 5 Land Reprocessing Plan.
Ordering MODIS Data Products from MODAPS and LAADS
Historically, MODAPS has exported forward processed and reprocessed
atmospheres and land data products to the GES DAAC and the LP DAAC/NSIDC DAAC
respectively. These DAACs have been responsible for subsequent distribution
to the end user community. Further, the GES DAAC has had the responsibility
for generating and distributing to end users the L1 and cloud mask data
products although MODAPS has also generated these products in the course of
its production from L0 data. In addition, the GES DAAC has been responsible
for acquiring the ancillary and ephemeris/attitude products and providing
these to MODAPS to support their production efforts. The DAACs have used
the EOS Data Gateway (EDG) as a mechanism for exporting data products to the
end user community.
The present transition of MODIS functionality from the GES DAAC to MODAPS
will not affect the export of land data products to the LP DAAC/NSIDC DAAC
for subsequent distribution to end users. The Collection 4 and 5 product
generation referenced above will continue to lead to MODAPS product export
to these DAACs.
At the end point of the GES DAAC/MODAPS transition in September the
following situation will prevail:
MODAPS will provide the principal archive for MODIS L0 data and MODAPS
will acquire these data from EDOS. These data will be maintained on disk.
The present archive is approximately 200TB in size and will grow at a rate
of 3TB/month. The backup will be the EDOS archive maintained at White
Sands in tape form.
The GES DAAC will continue to be responsible for the acquisition of
ancillary, ephemeris, and attitude data products and for providing these
to the MODAPS. However, MODAPS will archive all ancillary data in the
Level 1 and Atmosphere Archive and Distribution System (LAADS)
and will provide distribution services for these from this system.
Collection 5 L1 and cloud mask products will be generated and archived
solely by MODAPS. All Collection 5 geolocation and cloud mask/profiles
data products will be archived on disk in LAADS in compressed form for
subsequent distribution to end users. Some Collection 5 L1B products will
be archived in LAADS in compressed form. These correspond to the
continental U.S., Western Europe, and Southern Asia geographic regions.
The remaining L1B products will be archived in compressed form in a
"rolling" data pool that will have a capacity of approximately 25
production days (400 datadays). This data pool will be accessible by end
users through LAADS. MODAPS will not archive any Collection 5 L1A data
products or any L1 data products for Collection 4.
All MODAPS production activities for land and atmospheres L2+ products
will be for Collection 5. MODAPS will archive all atmospheres
Collection 5 data including cloud mask/profiles and browse products on
disk in LAADS in compressed form for subsequent distribution to end users.
MODAPS will also archive Collection 4 L2+ atmospheres data products in
LAADS in compressed form. Further, LAADS will archive the so-called
"golden month" atmospheres data products for all earlier Collections.
Certain land products have been identified by the atmospheres community as
being required to support atmospheres analyses. At the present time these
are limited to albedo data products that will be archived in LAADS from
the Collection 5 land reprocessing.
MODAPS will export all Collection 5 land products to the LP DAAC/NSIDC
DAAC for subsequent distribution to end users.
As noted, some of the archive items listed above are in a state of
transition from the GES DAAC to MODAPS. At present, the following situation
MODAPS continues to produce Aqua and Terra Collection 4 L1 and land
products and the latter continue to be exported to the LP and NSIDC DAACs.
MODAPS does not archive any Collection 4 L1 data products. Further the
GES DAAC stopped Collection 4 L1 data production on February 24, 2006.
MODAPS does not yet have a complete atmospheres L2 Collection 4 archive
and is in the process of transferring these data from the GES DAAC. Until
this is completed later this year, the GES DAAC remains the archive for
the L2 data. MODAPS has a complete archive of the atmospheres L3 data
MODAPS has a complete archive for the Aqua Collection 5 atmospheres
products a partial archive for the Terra products (see Reprocessing
above). The Aqua and Terra L1 products are being archived at MODAPS/LAADS
using the approach identified above. The GES DAAC is no longer
distributing Aqua L1 products but will continue to distribute Terra L1
products until these are available from MODAPS.
Additional details of the MODAPS data archive are at given at
Atmospheres Archive Table
and access instructions are provided at
Data Access. The
page provides a detailed identification of the data products presently
archived in LAADS.
MODAPS will utilize LAADS to distribute Level 1 and atmospheres data
products archived in this system as defined above. LAADS may be found at
and this system may be used to access any data products archived in the
permanent archive or L1B data products temporarily archived in the rolling
data pool as defined above. Any requests from end users for L1B data
products outside of the interval contained in the data pool will be
automatically processed by LAADS on a processing-on-demand (POD) basis.
Data may be retrieved from the LAADS/data pool archives by direct access
through anonymous FTP. The FTP site is
Further details of these access approaches are given in
Even under heavy load, LAADS is designed to perform searches and orders in
seconds except in circumstances in which POD or post-processing is
performed. In contrast to the EDG and the GES DAAC WHOM delivery systems,
LAADS includes a wide variety of post processing capabilities that have been
included in direct response to requests from the atmospheres user community.
These include metadata searches, recurring temporal searches, geographic
sub-setting, parameter sub-setting, sub-sampling, masking, mosaicing,
reprojection, and GeoTIFF parameter conversion. Details of the capabilities
of the current and future versions of LAADS are given at
MODAPS provides subscription services that provide individual users and
groups of users with data products at the time of their production. These
products are normally pushed to users but data products may also be added to
the data pool for subsequent data pull by end users. These subscriptions
may include limiting data products by geographic region. MODAPS also
accepts special user algorithms that can be incorporated into the production
activity as algorithm codes (referenced as Sub-setters) that generate
special products for user distribution through subscriptions. Subscriptions
and Sub-setters may be applied to both forward and reprocessing production
activities. Requests for subscriptions and sub-setters should be sent to
User Services at
MODAPS also process special ad hoc user requests (e.g. requests for
historical L1A data products) that should also sent to User Services.
At the completion of the GES DAAC/MODAPS transition process in
September 2006, the following data products will be distributed by MODAPS to
the general user community:
Aqua and Terra L0 data products. Small volumes of data will be provided
through LAADS. Bulk distributions will be made through direct access to
the L0 archive.
Aqua and Terra Collection 5 L1 data products will be provided through
LAADS. User requests for Collection 4 L1 data products will be processed
by MODAPS as ad hoc requests.
Aqua and Terra Collection 5 atmospheres data products (including cloud
mask/profiles) and certain land products (albedo) will be available
Aqua and Terra Collection 4 atmospheres data products (including cloud
mask/profiles) and golden month data products for earlier Collections will
be available through LAADS.
Aqua and Terra Collection 5 land data products will be exported by MODAPS
to the LP DAAC and the NSDIC DAAC for subsequent distribution to the
general user community.
Subscription and Sub-setter services will be provided for all Aqua and
Terra Collection 5 atmospheres and land data products generated by
forward and reprocessing production activities.
MODAPS will provide metadata and browse for L1 and atmospheres data
products archived in LAADS/data pool to the Earth Observing System
Clearing House (ECHO). Cross-DAAC data searches will be conducted using
the Warehouse Inventory Search Tool (WIST) and LAADS will be capable of
responding to data requests from that source.
LAADS will support McIDAS users.
None of the above products will be available through the GES DAAC.
As noted, some of the distribution items listed above are in a state of
transition from the GES DAAC to MODAPS. At present, the prevailing
Aqua and Terra L0 data products are available on a special request basis
by contacting User Services at
Aqua and some Terra Collection 5 L1 data products are available through
LAADS. These products are not available through the GES DAAC.
Terra Collection 5 L1 data products are available from the GES DAAC
Aqua and Terra Collection 4 L1 data products are available from the GES
DAAC for the time interval ending February 24, 2006. Requests for later
data should be submitted to MODAPS User Services at
Aqua and some Terra Collection 5 atmospheres products are available from
LAADS. These products are not available from the GES DAAC.
Aqua and Terra Collection 4 L3 data products are available from LAADS.
These products and the L2 data products are available from the GES DAAC.
The Golden Month data products for Collection 4 and earlier Collections
are available through the GES DAAC.
MODAPS is providing Subscription and Sub-setter services for Aqua and
Terra Collection 5 atmospheres reprocessing production and Aqua and Terra
Collection 4 atmospheres and land forward production. MODAPS is providing
these services for L1 Aqua and Terra forward processing. The GES DAAC
continues for Terra reprocessing.
MODAPS is exporting Collection atmospheres and L1 metadata and browse
products to ECHO.
MODAPS supports McIDAS users.
The authors appreciate that the transition process is confusing for end
users and reiterates that the comprehensive nature of the GES DAAC services
dictates that the transition should be a gradual process spanning over a
6-month time period. Please submit any questions to Gang Ye at
User Services, Frequently Asked Questions, and Quality Assurance
MODAPS operates a User Services group which includes both logistics/delivery
system and science support. The former acts as a single point-of-contact
for all user requests. The contact point is
User Services also maintains a toll-free (U.S. only) number: 1-866-506-6347.
The hours of operation are 9 a.m. to 5 p.m. EST Monday through Friday.
Requests for support through e-mail or the voice recording service are
monitored outside of these hours and response will be made to urgent
requests outside of the standard hours. Science support is provided by
Bill Ridgway at 301-614-6215 or
Additional details concerning User Services are given at
MODAPS maintains a list of frequently asked questions that is updated
frequently. These may be found at
Frequently Asked Questions.
The atmospheres Quality Assurance site is currently being developed.