In addition to the tools that select, manipulate, and visualize data, the Data Library makes those results and all data available in a variety of formats.
For the most part, the process of downloading data is very straight forward. A brief discuss is offered here.
Let us use the popular Malawi monthly rainfall climatologies dataset to take a closer look at the available data formats.
Start with the monthly rainfall climatology data*.
Select the Tables link in the function tabs.
There are three different types of tables available here. The array tables present
data in your browser and you can select the orientation of the grids with the associated
links. Feel free to select these links to get a feel of how the data is presented.
Selecting one of the links for the tab-separated tables will immediately give you
the opportunity to download that table. The columnar tables, like the array tables,
are shown in your browser. However, there are some added features, including selecting
file type and missing data markers, under the "columnar tables with options" link.
While these
three types of tables are often very convenient, they are best used for small amounts
of data. Let us look at the options more suitable for downloading large data files.
Go back to the rainfall climatology page using the Back button on your browser.
CHECK
Select the Data Files link in the function tabs.
The amount of data you have selected will be at the top of this page. In this case,
we have selected 930384 bytes of data. This feature can be extremely helpful when
determining how large the resulting data file will be. Next, we see an alert to potential
problems if we intend on using specific software (e.g., COARDS, GRADS). If you plan
on using the software that is shown in this section, then you may wish to utilize
these options to adjust the format of your data.
All of the data formats available here primarily differ in one respect- how much ancillary information they contain. The ancillary information includes much of what you see on a data variable page including grid and data characteristic information. Two formats/protocols, DODS and netCDF, are generally available if you would prefer to store this information. You can download data in these formats by selecting the appropriate link. Some of the table options we saw before are also available here and store some of the ancillary information. In addition, GIS users may find it convenient to download data with an ArcInfo Header via the "ArcInfo ascii GRID datafile" link. Data can also be downloaded with no ancillary information in binary, table, or text format.
We start with the image* of just the Jan rainfall climatology for this discussion.
Select the "more options" button in the table below the image.
You can now see all of the options for saving an image. There are three options for
creating a single page with the image: 1) documented, 2) image only, and 3) data-linked
image. You can find these options in the Page Formats row of the table. There are
also PostScript, JPEG, and GIF formats available for saving the image and scale separately.
You can find these options in the bottom two rows of the table.
If you have any further questions about downloading data, you may want to look at the previously-asked questions about this topic.
| FORMAT | APPLICATION |
|---|---|
| ascii with ArcInfo Header | ArcInfo |
| IDA | WinDisp, GIS applications |
| ERDAS LAN | GIS applications |
| netCDF | |
| tables | Spreadsheets |
| binary random access | |
| DEC ALPHA direct access | |
| binary FORTRAN sequential access | |
| DEC ALPHA sequential access | |
| JPEG | |
| GIF | |
| PS |
Data can also be accessed using a DODS (OPenDAP) client from a variety of software, including Matlab, GrADS, and Ferret.