Getting Started with MODIS Version 6 Vegetation Indices Data Part 1
This video focuses on the National Aeronautics and Space Administration’s (NASA) Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Version 6 Vegetation Indices data distributed by NASA’s Land Processes Distributed Active Archive Center (LP DAAC). Information about the MODIS Version 6 Vegetation Indices products, changes between the Version 5 and Version 6 products, and how to access the data using NASA’s Earthdata Search is provided. To learn more about MODIS Version 6 Vegetation Indices data and other data products distributed by the LP DAAC please visit https://lpdaac.usgs.gov/.
The LP DAAC is one of twelve NASA Earth Observing System Data and Information System (EOSDIS) DAACs. It is located at the United States Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center in Sioux Falls, South Dakota. The LP DAAC ingests, archives, processes and distributes NASA Earth science land processes data and information.
Location Taken: Sioux Falls, SD, US
Video Credits: Content created by Danielle Golon (Contractor to USGS EROS)
Getting Started with MODIS Version 6 Vegetation Indices Data Part 1: All About Accessing the Data. Presented by the Land Processes Distributed Active Archive Center or LP DAAC. This video is part 1 of the “Getting Started with MODIS Version 6 Vegetation Indices Data” video series. This video will cover the MODIS Version 6 Vegetation Indices data products, improvements in Version 6 products over Version 5 products, and how to search for and download these data using the Earthdata Search Client data access tool. The LP DAAC distributes several MODIS Version 6 Vegetation Indices products. All data distributed by the LP DAAC are available for download at no charge. These data products provide information on the Normalized Difference Vegetation Index or NDVI and the Enhanced Vegetation Index or EVI, which are measures of the greenness of vegetation. These products provide 16-day and monthly coverage, with spatial resolution ranging from 250 to 5,600 meters. MODIS Vegetation Indices data products are either tiled and in sinusoidal grid projection or are Global Climate Modeling Grid or CMG products that are projected to a latitude-longitude grid. Detailed information about each of the individual products can be found on the LP DAAC website at lpdaac.usgs.gov. The MODIS data collection is reprocessed into a new version every so often to provide users with improved products. There are several improvements that were included in the reprocessing of the Vegetation Indices data products. Improvements include: creating the 16-day product using the two 8-day surface reflectance granules within each 16-day window, which previously used 16 daily granules, a new compositing method for the 8-day composited surface reflectance input granules that minimizes the impact from aerosols, an improved EVI data backup algorithm that is used over high-reflectance surfaces, such as clouds and ice, and gaps in the CMG product suite are now filled in using an updated database. More detailed information on the changes to each of the MODIS Vegetation Indices products can be found on the Digital Object Identifier or DOI Landing page on the LP DAAC website. The LP DAAC website also offers several ways to download MODIS Vegetation Indices data products. At the bottom of the DOI Landing Page for each product are links to the data access tools for the specific data product. In this video, step-by-step information for downloading data using NASA’s Earthdata Search Client data access tool will be demonstrated. From the Earthdata Search home page, search.earthdata.nasa.gov, click on the “Earthdata Login” button to login with your NASA Earthdata account. If you do not have an Earthdata account, click on the register button and follow the prompt to create one. Now, search for the Terra MODIS Version 6 Monthly Vegetation Indices 1 kilometer level 3 gridded product, MOD13A3. Type “MOD13A3” in the search bar and hit enter. Click on the MOD13A3 Version 6 data product. This will pull up all of the MOD13A3 granules. Parameters for a specific time and location can be set above the map. For this video let’s look at monthly Vegetation Indices in the United States in the state of New York from the year 2015. First, pan and zoom the map to New York. Change the temporal range by clicking on “Temporal” and then click on the Start date and change the date to “January 1, 2015.” Now, change the End date to “December 31, 2015” and click on apply filter. To change the spatial information, click on “Spatial” and select “polygon” from the drop down menu. Draw a polygon around New York. You will now see green outlines that indicate the footprint of the Terra MODIS tiles contained in your polygon. The granules from 2015 that are located in the selected area are now listed in the lower left hand corner of your window. Above the granule list are options to “Retrieve Collection Data” which allows a user to download all of the matching granules, an “i” icon to learn more about the data collection, a filter icon to further filter the data, and a plus sign icon, which allows a user to add multiple data products to their Earthdata Search project. Click on the first box in the lower left hand corner list to select the most recent scene in the list. This box contains a preview of the granule, the Terra MODIS filename, the dates of the data, an “x” in the upper right hand corner to remove the scene from your granule list, an “i” for more information, and the retrieval icon to download a single granule. Click on the “i” icon to bring up the metadata for the selected granule. Remember, metadata are data about data. The metadata include the DOI, which is necessary for proper citation, as well as information on the scene’s corner coordinates, input granules, and more. Click on the “Metadata” tab for links to download metadata in different standard formats. Click on “Back to Granules” to return to the granule list. Click on “Retrieve Collection Data” to download all of the granules in the granule list. Now, review the data download order on the “Data Access” page, this page lists the number of granules in the order and the size of the order. From here users can select the service options. Select “download” to instantly receive the granules in the order or select “Delivery Option” to receive the granules via email. The “MOD13A3.6 ESI Service” option allows the user to select various service options, including reformatting the data from a Hierarchical Data Format or HDF file to a GeoTIFF or to other file formats. From here you can also spatial subset the data, re-project the data, and subset the science datasets. Click on “submit” or “continue” and then “submit” to submit the order. Depending on the data access method, the data can be accessed immediately or will be sent to the user via email. Thank you for watching our video. For more information on MODIS Version 6 Vegetation Indices data please visit the LP DAAC website at lpdaac.usgs.gov.