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Eight Day Global
Frequently Asked Quesitons
Grids & Mapping
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Algorithm Software
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Algorithm Software

The DRL Institutional Algorithm Service

The Direct Readout Lab (DRL) provides an Institutional Algorithm site as a distribution mechanism for MODIS Level-2 science software algorithms to the direct broadcast user community. The software on the DRL site is the same code supplied by science team members as part of the large, integrated MODIS Operations Data Processing System (MODAPS) operating at Goddard. The MODAPS system processes geolocated, calibrated radiances to Level-2 data products in a chained production mode. Institutional algorithms will not run in a standalone mode without environment variable changes, ancillary data sets, and prior processing steps. Therefore, the user must make the necessary changes and environment set-ups to run these algorithms. DRL provides information and guidance on how to use each of these algorithms. Additionally, users may consider using these algorithms as guidance in creating their own software for processing MODIS instrument data.

Algorithm Organization

The algorithms are grouped by the PGE (Product Generation Executable). Each PGE page contains information such as, an overview of the code, required inputs, output files, build and run guidelines, and additional related links. The L3 Eight-Day algorithm is part of PGE70.

Available Support

End users are responsible for compiling and installing the code for their particular computer platform. However, the DRL encourages user feedback regarding your successes and difficulties in implementing these algorithms to help improve the documention. In addition to providing software and algorithms, the DRL will provide notification via email and site updates when new versions are available. Anyone interested in providing feedback or having questions of any kind please use DRL's Feedback or Contact us button. All input is valuable and will be considered for future releases.

Obtaining a Software Download Account

In order to download any DRL-provided Software/Algorithm from the Direct Readout Portal, the user must complete the User Account Form. The data collected from the form will be stored in a local database and will be used for authentication purposes only. This data collection is necessary only for the first time you download any software. For all subsequent download attempts, only the username and password will be required (unique username and password are emailed to the first time users after they successfully complete the form).

Download Software

In order to download any of the algorithms, the user MUST electronically sign a software disclosure form for each algorithm. To make this process easier for the user, the DRL offers a Member Login Page that allows the user to be authenticated. Upon authentication, a form for the requested software appears with the user's information already inserted. It is the responsibility of the user to read the disclosure document and click agree or disagree. Upon agreement to the disclosure, the user will be redirected to the software download page.

Download PGE70 Software and Test Data
Download PGE70

Software, Documentation, and Process Files

The MOD08_E3 HDF product is produced in a multi-step process. The global grids within the HDF structure file are generated by the MOD_PR08EC process and the grids are populated by the MOD_PR08E process. Detailed descriptions of the programs are given below.

    Eight-Day Global Structure File Creation (MOD_PR08EC)

      The MOD_PR08EC process creates a global HDF structure file that contains the global attributes, 650 (empty) Scientific Data Sets (SDS's) and their associated local attributes.

    Eight-Day Global File Population (MOD_PR08E)

      The MOD_PR08E process aggregates eight consecutive daily global product files.

    Shared Source Code

      Finally, some of the subroutines and functions are shared between all of the Level-3 processes.