The following page provides some information on how to use our digital library portal. If the information provided does not answer your question, or you would like to provide feedback or even make a suggestion then you can send us an email using our online contact form.
Overview: Data sets are grouped into categories, and these are listed on the front page of the portal. The data sets available within each category can be viewed by clicking on the category title - this brings up the data set view page. This page provides a more detailed description of the category, and lists the available data sets. Clicking on a data set name will bring up the search view page. This page lists all the files contained within a data set: you can specify which data set attributes to display; you can sort on these attributes; and specify search criteria based on these attributes.
You can collect links (OPeNDAP URLs) from various searches into a links collection (which behaves much like an online retailer's shopping cart). The links can be stored from many searches and later downloaded as a single file. This allows easy insertion of the URLs into scientific applications such as Matlab or Ferret.
Please note that most of the images on this page are links that will bring up a popup window to display a more detailed view of the image.
 Portal Front Page: Data sets are grouped into categories. |
 Data Set View Page: Lists data sets contained within a category. |
 Search View Page: Lists files contained within a data set. |
 Download Links Page: Allows downloading saved URLs.
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Navigation: you can move between the various pages by using the navigation bar at the top left of each screen.
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Global search: you can perform a global search using the search box at the top right of each screen. This will search both category and data set descriptions, and also data file names and locations.
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Dataset Information: The panel on the right-hand side of the search view page provides useful information about the data set - it may also contain links to other resources. There will be a brief description of the data set. Some data sets may have a more detailed description link, which will be displayed in a popup window.
The "Data URL" (or root OPeNDAP reference) for this data set is also provided. Clicking on this link will give you an OPeNDAP directory view of the data set. This is the traditional way of navigating an OPeNDAP server. In this view, clicking on a file name will bring up the standard "DODS Access" form, which will allow you to view the file attributes and construct an OPeNDAP URL for that file.
The person (or organisation) responsible for maintaining the data set is also listed. The link provided allows you to send an email to that person if you have any queries about the data.
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Dataset Attributes: Files in a data set will contain one or more variables each of which may have a number of associated attributes. The variables and associated attributes for the entire data set are listed in the drop-down menu. You can choose which attributes to display by selecting them from the menu - the attributes are listed under the variable names (see right-hand figure). After selecting an attribute, click the "Add" button.
The attribute values are displayed in additional columns to the right of the file names (see the File Display section below). Also, a search criteria field for that attribute is added to the "Search Options" section of the panel. This allows you to perform searches based on that attribute. If the value of the attribute is a string, only a single search field is displayed; if the attribute value is numeric, two search fields are added. The attributes are labelled using the following annotation, variable:attribute.
Note: additonal attributes associated with the OPeNDAP server are provided under the DODS_EXTRA and FILE_EXTRA variable names. Unlike the other attributes, these are not actual values stored in the data files, but are based on information provided by the server. Selecting these attributes will allow you to perform searches based on the names of files (file_name), their location on the server (file_directory), or on their OPeNDAP URL (file_url). Note that the FILE_EXTRA:file_name attribute is always displayed by default.
You can perform searches by entering values into the search fields. Exact matches are made on strings (you can use * as a wildcard). After entering your search criteria, select the "Apply" button. Only files matching your search crieria will be displayed - the number of matches is shown at the top right-hand side of the panel. You can control the number of files displayed per page by adjusting the results per page setting.
Selecting the "Clear All" button will clear all values from the search fields, and return to displaying all files. Selecting "Remove All" will remove the search fields and value display columns for all the attributes that you have chosen to display.
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Directory Select: Data sets that have detailed directory layouts can be traversed using the "Select Directory" panel. By default, all files from all directories are displayed. If you select a directory from the drop-down menu, only files in that location are shown. You can move back up the directory tree by clicking on the directory links to the left of the drop-down menu.
An alternative method of traversing directories is to add the FILE_EXTRA:file_directory attribute, and then enter the required directory path into that attribute's search field. For example, entering /20c3m/ocn/mo into the search field will list the same set of files as given by the "Select Directory" panel figure.
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File Display: Files matching your search criteria are displayed over multiple pages. You can select which page to display by clicking on the page numbers at the top and bottom right of the file listing. Clicking on a file name will display the standard "DODS Access" form for that file in a separate window.
You can sort the file listing on any attribute by clicking on the attribute label at the top of each column. Clicking on the attribute label a seond time will toggle between ascending and descending sort order (as shown by the direction of the arrow head to the right of the attribute label).
There are two green icons to the left of each file name. The "i" icon displays all the attributes for a file in a popup window. This is the same information that is available on the "DODS Access" form, but in a more compact presentation. The "D" icon allows you to download the raw data file in the same format as stored on the server (this will usually be netCDF or HDF format). Note that this download method completely bypasses the OPeNDAP server mechanism so no subsampling functionality is available - the entire file is downloaded.
Files of interest whose OPeNDAP URL reference you want to save for later use (see the Links Collection section below) can be selected by checking the box next to left of each file name. After you have made your selection, click on the "Save Selection" button at the bottom of the file listing. You can save all file URL references listed on the current page by clicking on the "Save All" button.
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Links Collection: Each time you visit the portal you start a new session, during which you maintain a unique links collection where you can store OPeNDAP URL references to files. The number of references you currently have stored is shown by the links collection status at the top right-hand corner of each screen - to the left of the global search field.
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During a session you can perform multiple searches across many data sets, saving your selected file URL references as you go. You can download these saved references in a single text file at the end of your session. You access the links collection download page at any stage by clicking on the links collection status link.
On the download page you can further modify your selection by using the check boxes to the left of each file name in conjunction with the "Remove Selected" button. You can also enter a comment that will be included in the downloaded text file. This is useful for including a general description of the group of file references that you have collected.
Select the "Download URLs" button to begin the download process. You will be given the option of entering a file name for the downloaded file.
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