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Downloading Data |
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Downloading Data |
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After learning about the tools that select, manipulate, and visualize data, the next natural step is to learn how to obtain those data. The Data Library makes 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.
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1. Data Files |
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2. Data Images |
Let's use the popular Reanalysis dataset to take a closer look at the available data formats.
Start with the monthly climatological mean sea level pressure Reanalysis data*.
Select the Tables link in the function bar.
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's look
at the options more suitable for downloading large data files.
Go back to the mean sea level pressure page using the Back button on your browser.
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Select the Data Files link in the function bar.
The amount of data you have selected will be at the top of this page. In this case, we have
selected 504,576 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 climatological mean sea level pressure 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.