Searching Archived Data Files for Specific Strings

The Search Data Files operation is a useful tool for finding a particular measurement. It enables you to search a data file header variable in one or more archives for specific strings, and view a table of the search results. The table lists the files of interest by mission name and file name code, and includes links to the directories holding the files of interest. File name codes, described in File Names, are what remains of the file names after the date/time and launch indicators are removed. They are merely a convenient way to refer to a particular type of file, and are unique within any particular archive but not necessarily between different archives.

Several file header variables can be searched and, to some degree, the success of the search depends on how closely their values follow the conventions for defining those variables, which are described in File Formats. The expected information in the header variables is:

ONAME
The names of the originators of the file, which often includes the PI responsible for the data.
ORG
The organizational affiliation of the originator of the file, and may include contact information like email address, phone number, etc.
SNAME
The source of the measurements or model results recorded in the file, including the names of the measurement platform and instrument.
vname
This is a catch-all for all independent and dependent variable names (XNAME, ANAME, VNAME), which include the name or description and units of measure of all data variables recorded in the file.
The database of these variable names is only updated a couple times per day, so it may take several hours before entries from newly archived files appear in the database and in your search results.

Search Strings

On the web form you can enter one or more space-separated search strings. The search for each string is case-insensitive and independent of the order in which you enter the strings, and the result is a list of all variable values which are matched by any of the search strings. Each search string is actually a Regular Expression, so if you know about those things then you're good to go. If not, it's no big deal; you can still find what you want without much effort by treating each search string as a case-insensitive keyword, and searching on multiple keywords. Operating in that mode you are likely to find what you want, and more.

For example, suppose you are looking for ozone measurements in several selected mission archives, and you select the vname variable and enter the search strings: 

ozone o3
The first string, ozone, will match any occurrence of ozone, including: OZONE Ozone ozonesonde. The second search string, o3, will match any occurrence of o3, including: O3 o3 NO3.

Ooops. That is probably more than you are looking for, so you can limit your search and ignore things like NO3 ClNO3 by using the search strings: 

ozone \bo3\b
Quoting a string with \b tells the search to only match the target string when it forms a complete "word", where a "word" is a sequence of letters, digits and underscores. Spaces, punctuation marks and the beginning and end of a line delimit "words", so using \bo3\b as a search string will match O3 o3 O3-sonde, but not NO3 because O3 is not a "word" in that string.

There are some characters which foul the search, so they are automatically removed from the search strings. Those outcasts include the non-printable ASCII characters and the single quote, double quote, and backquote.

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Curator: Steven Gaines  -  NASA Official: Mike Craig
Updated: 2005-02-11