How To: Get Access to Data

Use Case:
You are interested in gathering calibration/validation data (both remote sensing and in-situ) for a certain instrument / calibration project. Following the steps below, you will learn how to get these data through the CalVal Portal.

Satellite Data

  • On the navigation bar on the left side, select 'Access to Data'.
    --> you will find some general information on the data available through the portal (sources, format, downloads etc.)

  • On the navigation bar on the left side, select 'Access to Data --> Satellite'.
    --> you will obtain a mask with input elements to further specify your search with regard to
    • Region (Category/Site)
    • Time Range
    • Product Type
    • Product Archive

    Furthermore, a world map is displayed on the right side which shows the location of all sites which are specified by the selection from the 'Region' (Category) drop-down menu. Initially, all sites which are provided by the CalVal Portal are displayed ('all categories / all sites'). This map offers common navigation mechanisms (horizontal/vertical shifting, zoom), and also the choice between a simple background map (OpenLayers WMS) and a nicer NASA BlueMarble background image ('plus' button in the upper right of the map display area).

  • From the 'Region' (Category) drop-down menu, select 'MAVT'.
    --> in the 'Region' (Site) drop-down menu, only the sites related to the category 'MAVT' are displayed. Also, the sites displayed in the world map are reduced to this subset.

  • From the 'Region' (Site) drop-down menu, select a specific site, e.g. 'AAOT'
    --> underneath the drop-down menu, information on this site is displayed:
    • Site Type
    • Center Lon./Lat.
    • Radius
    • Elevation

    In the world map, this site is highlighted in red.

  • From the 'Time Range' drop-down menu, select a specific period, e.g. the current year starting at Jan 1st.

  • From the 'Product Type' drop-down menu, select a specific product, e.g. 'MER_RR__1P'.

  • Make sure that from the 'Product Archives' checkboxes, the 'Local Archive' checkbox is selected. (Note that the current version of the CalVal Portal only provides access to the local archive. Future versions will also provide access to remote catalogues such as EOLI.)

  • Submit Query.
    --> A result set will be displayed below the selection mask. You will find quicklooks of the products and some brief information (filename, date/time, and product type). In the world map, the swaths corresponding to the results are properly displayed.

  • Click on the filename of a product.
    --> You will now obtain a 'Detailed Satellite Product Information'. Additional information is provided here, such as raster width/height, file size, start/stop date, and all sites covered by this product.

  • Go back to the result set page. Each of the product files can now be selected for download. (Note that you must be logged in to download datasets. See section 'General Information' on how to get an account for the CalVal Portal.) There are two download options provided by the portal:
    • Download 'as is' (the original product)
    • Download as ascii subset of size (pixels):
      • 5x5
      • 10x10
      • 20x20
      • 50x50

  • Select a checkbox of a product. Then click on the button 'Download'.
    --> A download dialog opens which gives you the choice to save the original product to your disk.

  • Now select the option 'download as ascii subset'. Then click again on the button 'Download'.
    --> A download dialog opens which gives you the choice to save an ascii subset to your disk. This ascii subset is a zip archive containing one (or more) file(s) with the extension '_ascii_subset_for_site_....txt', which in turn contain the product subset in a widely self-explaining ascii format.

In-Situ Data

  • On the navigation bar on the left side, select 'Access to Data --> In-Situ/Reference'.
    --> you will obtain a list with links to the 'Local' access (in-situ data stored in the CalVal Portal), and also to external sources which provide in-situ data

  • From this list, select 'Local'.
    --> similar to the satellite data access, you will obtain a mask with input elements to further specify your search here with regard to
    • Region (Category/Site)
    • Time Range
    • Measurement Type

    Again, a world map is displayed on the right side which provides the same functionalities as for the satellite data search.

  • Select the same region/site and time range as for the satellite data search before. Keep the 'Measurement Type' on 'any type'. Submit Query.
    --> A result set will be displayed below the selection mask. You will find a list of the products and some brief information (date, originator with external link, size of 'additional data', measurement type, and location). In the world map, the swaths corresponding to the results are properly displayed.

  • Each of the product files can now be selected for download. (Note that you must again be logged in to download datasets. See section 'General Information' on how to get an account for the CalVal Portal.) There are two further download options:
    • 'Select all' - with this checkbox, all data products can be (de-)selected for download
    • Include additional data - this option must be selected to download the whole datasets provided by the portal. If this option is deselected, the selected datasets will only consist of a csv file giving the location of the site.

  • Select a checkbox of one or more products. Then click on the button 'Download'.
    --> A download dialog opens which gives you the choice to save the products to your disk. The products come as zip archive containing files which in detail depend on the type of measurement and on the number of products included in the download.
The Committee on Earth Observation Satellites (CEOS) is providing information and data for Calibration (Cal) and Validation (Val) of Earth Observation (EO) data through this portal.