Data Pool

Data Pool Help

Topics

Procedures
     · Data Group
     · ESDT
     · Date
     · Time
     · Spatial Coverage
     · Day/Night Flag
     · Science QA
Viewing Results
   - Results Table
   - Metadata Table
   - Granule
Downloading Science Data
Viewing Metadata
Viewing Browse
Shopping Cart

This document explains how to use the Data Pool interface to search for science data. Each screen displays the current search criteria table at the top, showing the elements you chose in previous steps. Each page also gives you a list of options. These usually include the options for how to select the values for the displayed criteria, an option to skip the current step, and a link to start a new search. The options list also includes a link to go directly to the results of the current search criteria by clicking Get the granules, which returns the data in a table.

On any page in the interface, you may need to scroll down to view all the options or buttons for the current search element.

Procedures

  1. From any page on the Data Pool site, click the Search the Data Pool link. This displays the Data Pool search interface, which shows the Data Group table.
  2. From the Data Group table, click on the type of data you want to search. The next page shows the Current Search Criteria table at the top, and the Earth Science Data Type (ESDT) table below it.
  3. The ESDT table shows the reference name for a data set. For example, MOD10A1.3 refers to the MODIS/Terra Snow Cover Daily L3 Global 500m ISIN Grid, Version 3 data set. From the ESDT table, click the name of a data set to search. The ESDT parameter is mandatory (the search cannot continue without it). This displays the Day, Week, or Month page.
  4. On the Day, Week or Month page, you can select a date or date range in the following ways:
    • Click on an option in the table.
    • Select a date range from the drop-down lists below the table and click Add it to your search criteria. If your date or date range is not applicable to the data set, the next page instructs you to go back and choose other dates.
    If your date criteria are applicable, the Time of Day page displays.
  5. In the Time of Day page, you can select a time or a time range in the following ways:
    • Click on an option in the table.
    • Select a time range from the drop-down lists below the table and click Add it to your search criteria. If your time or time range is not applicable to the data set, the next page instructs you to go back and choose other times.
    If your date criteria are applicable, the Select from Map page displays.
  6. In the Select from Map page, you can select spatial coordinates in the following ways:
    • Click and drag your mouse on the appropriate coordinates in the table. There are several options for choosing parameters this way:
      • LLBox - LLBox stands for Latitude/Longitude box, which is defined by north and south latitude (meridians) and east and west longitude (great circle arcs). Select the Rectangle check box at the bottom of the map window. Click and drag the mouse on the map to create the bounding box you want. Click Add Selection to Search.
      • Polygon - This type of region is composed of pairs of latitude/longitude coordinates. Each of the arcs between a pair of points is defined as a great circle arc. This region can be irregular, except that it cannot have crossed lines. To create a polygon, select the Polygon mode at the bottom of the map window. Click on the map to enter points. Click Add Selection to Search.
      • Tile - Tile is essentially an LLBox, but with important differences in how you define it. Select Tile mode from the applet and move your mouse over the map. The tiles are highlighted as the mouse passes over them. To control the size of the tiles displayed, select a Grid check box from the left side of the map window (these are in degree increments; a one-degree grid increment is the smallest). When you find the tile you want, click the mouse. This action immediately enters your search selection and displays the next page.
    • Type the longitude and latitude coordinates in the text fields below the table and click Add Selection to Search. If your coordinate range is not applicable to the data set, the next page instructs you to go back and choose other coordinates. If your spatial criteria are applicable, the Day/Night page displays.
  7. On the Day/Night page, the applicable times appear as links in the table. Click on a value in the table. The Select Measured Parameter page displays.
  8. On the Select Measured Parameter page, select a parameter from the drop-down list. The Science QA table below it lists the available links for the Science QA values. Click on a Science QA link. The Results page displays. For information on reading the results, see Viewing Data Pool Search Results.

Viewing Data Pool Search Results

As on other pages, the Search Criteria table lists the parameters that you chose for the search. To modify any of the parameters you chose, you can click on the links in the table.

The Data Pool search results display within a table that gives you options for how to view the data.

Table Layout

Metadata Display

The first row of the Results table is the Metadata Display, which lets you define how to view the table results. The table initially displays the Size, Temporal, Day/Night data. The Cols drop-down menu at the top of the table provides two additional links, ScienceQA and Cloud Cover%.

  • ScienceQA displays the results listed by the quality of the measured parameters. The Science Quality Flag (often referred to as ScienceQA) refers to the science quality (defined by the instrument team) of a particular measured parameter (such as the radiance of a certain wavelength). Science Quality flags are either:
    • Passed - The granule (for the parameter) has passed a specified science test.
    • Failed - The granule (for the parameter) has failed a specified science test.
    • Being Investigated - The granule (for the parameter) is being investigated by an expert.
    • Validated - The granule (for the parameter) has been validated by an expert.
    • Not Investigated - The granule (for the parameter) has not been investigated by an expert.
  • Cloud Cover% displays the results listed by the cloud cover percentage of the measured parameters.

Click on the ScienceQA or Cloud Cover% links to view the results in those terms.

Set the maximum number of data sets displayed by changing the value in the #Rows drop-down menu.

Granule

Granule - The granule column contains the name of the granule and several optional icons. The name is actually a part of the granule UR (the granule id) and displays as a link if there is a science file present for this granule. There are several icons for each granule. The icons are described below, along with instructions on how to use them.

Download file icons provide links to the granule science file (containing the actual science data for the granule). See Downloading Science Data.

download file icon  Download HDF granule, uncompressed
download file icon  Download HDF granule, compressed in ZIP format
download file icon  Download HDF granule, compressed in gzip format
download file icon  Download HDF granule, compressed in Unix

An Extended Markup Language (XML) file icon (metadata file icon), which is a link to the full metadata of the granule in .xml format. See Viewing Metadata.

A Browse icon (browse file icon), which is a link to the granule browse image (a .jpg file). See Viewing Browse Imagery.

A Browse and metadata icon (browse and metadata file icon), which is a link to the granule browse image and XML metadata.

A Convert and subset icon (convert and subset file icon), which is a link to a page where you can convert the format and projection, and perform spatial subsetting of the selected data granule. See Converting and Subsetting.

A Shopping cart icon (download file icon), which allows you to select granules to place in a shopping cart while you search for other data. See Shopping Cart.

In each case, these icons appear if the corresponding data are available in Data Pool.

Downloading Science Data

To use FTP to transfer the granule's science file to your computer, click on any of the icons described in the Download section. If there is only a single science file for your granule, the FTP link displays a Save As dialog. If the granule has multiple science files associated with it, when you click on the FTP link, a dialog containing links for the multiple science files will appear. Click on the individual links to get the science files.

Note: Each of the file links displayed for downloading files is an FTP link. It is possible that the browser will not understand the file type referenced in the this link, and may try to render it as text.(If you're using Internet Explorer, you shouldn't have this problem if you use Version 5.5 or greater. If you are using an older version, you should upgrade it.) Use one of the following steps to make sure that the file is saved in the correct format:

  • Right-click (or option|click on a Mac) on the link. This displays the option menu. Select the Save Link As... option from the menu. The Save As dialog box appears, allowing to you to save the science file to your disk.
  • If you're using Netscape, set a helper type in your browser preferences. This allows you to click normally on these links and get the Save As dialog.
    1. From the Edit menu, select Preferences. This displays the Netscape: Preferences dialog.
    2. From the Category list on the left, select Navigator and then Helper Applications. On the right side of the dialog, a list of application helpers displays, along with some controls (New Type, Edit, Remove).
    3. Select New Type. The Netscape: Application dialog appears with a listing of field names (Description, MIMEType, etc.). Fill in the fields on this dialog as listed below:
      Description: DataPool Files
      MIMEType: application/ftp
      File extension/Suffixes: hdf,hdfeos,eds,xml,dpl,r10
      Application to use/Handled By: select Unknown:PromptUser

Viewing Metadata

To view the full metadata of a granule, click on the XML () icon. This displays a new browser window showing the full metadata hierarchy for the granule. To view the whole metadata hierarchy, scroll down or expand the window. Navigation links let you navigate the metadata hierarchies between granules. To save the XML file to your local disk, click Save. A Save As... dialog appears, where you designate the file name and location.
Note: The same problem described for downloading science files above can occur when trying to save the xml file. Please see the section above for problem description and solutions.

Viewing Browse Imagery

Note: Click on the Browse () icon to display the browse viewer. For granules with multiple browse images, the images are currently shown in a scrollable area with the browse viewer (scroll down to see all of the browse images in this case). To save any of the images, right-click on the image. A popup menu appears. Select Save As... or Save Image As.... A Save As... dialog appears, where you designate the file name and location.

Converting and Subsetting

You can choose an output data format and geographic projection, and spatially subset data granules using the HDF-EOS to GeoTIFF converter (HEG). This option is available for most MODIS data sets available at NSIDC. Refer to Table 1.

  1. Select the Convert and subset icon (convert and subset file icon)
  2. A Select Conversion Parameters for this Granule window appears.
  3. Under Format & Projection, select HDF-EOS Geographic or GeoTIFF Geographic.
  4. Enter latitude and longitude coordinates in the Spatial Subset fields.
  5. Enter your name and e-mail address in the Download Profile fields.
  6. Click on Convert this granule.
  7. An Order Acknowledgement window appears and you will receive an e-mail containing your order ID and a link to access the converted and subsetted data granule.

Convertable MODIS Version 5 Data Sets

Table 1. Convertable MODIS Version 5 Data Sets

Shopping Cart

The shopping cart is a new feature in the Data Pool. This option allows you to select one or more granules to place in a shopping cart, so you can search and order data with different criteria and download everything from one location when finished.

When you click on the shopping cart icon (download file icon), the cart displays a list of granules, options for global conversion utilities, and download information. You may select individual granules for FTP download or download all the granules in the list. You may also simply choose to download granules without any conversion. Granules added to the cart will stay in the cart unless you remove them, or until you successfully submit an order. You can return to your results list or start a new search at any time. The shopping cart will remain active during your session only. This page cannot be bookmarked.

For downloads with formatting and projection changes or spatial subsetting, you will receive two e-mails from the Data Pool: one is an acknowledgement of your order and another contains the results of your order. The acknowledgement e-mail contains an order ID. The order e-mail is sent when your download request is fulfilled, and it contains a link to your files. You will have a limited period to access the files via FTP from the download site, before files are automatically deleted.


Page last updated: 01/11/13