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Please note that, as of 02 June 2008, the Polar Spatial Query tool (PSQ) is no longer available. The machine on which PSQ resided has reached its life expectancy and we do not plan to rectify the machine or the PSQ tool. Thus, orders placed after 02 June 2008 will not be fulfilled. Please contact NSIDC User Services if you have questions or concerns regarding the PSQ tool.
The PSQ (Polar Spatial Query) tool is a web-based interface for ordering orbit and scene data sets from the National Snow and Ice Data Center (NSIDC).
The PSQ project is a prototype that demonstrates orbit-based searching of data and back end processing of differing data sets to a common, user defined grid. Because the search is orbit-based the results will be more accurate. Because the results are gridded to the users' region of interest, this tool can effectively reduce delivered data volume while facilitating data intercomparison.
General Keywords Date Range Geographic Results User Info etc.
This applet allows you to construct and submit a query based on temporal and spatial coverages of the data and the keywords contained in the metadata.
Two rows of buttons at the bottom of the PSQ allow you to navigate between panels and perform various functions that are common to all the panels in the PSQ. You can get help on each individual panel by navigating within this page.
The buttons at the bottom of the applet achieve the following:
The arrows on the first three buttons indicate the next step of the search procedure.
The status bar at the bottom of the applet tells you the next step of the search procedure as you go along.
General Keywords Date Range Geographic Results User Info etc.
The Keywords panel is the first panel to display in the PSQ and allows the user to specify a collection and parameter(s) to search for within that collection. The user may select one or more collections and one or more parameters within each collection.
Caveats: The default condition is that no collection or parameters are selected, but a user must choose something.
General Keywords Date Range Geographic Results User Info etc.
This panel allows the user to specify a a date range. At the top is a graphical display that provides visual feedback for the way the search range (in red) interacts with the metadata temporal range (in green). The user may define the search limits as a Range or as a number of days Relative to the current day.
Caveats: Two digit years are not allowed. If you try to use a two digit year the program assumes you mean the year "00YY".
In general you need to be careful to enter the date in the defined format. Just as you cannot use two digit years you also cannot use one digit months or days.
If you set the start date to be later than the end date, or the end date to be earlier than the start date, you will not be allowed to perform a search until that is corrected.
If you choose a date format that does not include months or days, those values remain what they were before you changed the format, and they will not be displayed. If you want the beginning or end of a month or year you need to explicitly set those dates.
The program accepts invalid dates but the database does not.
This part of the applet is very old. We plan to upgrade this module to Java2 in the future and add some useful functionality like annual periods, daily periods, and possibly an interactive display. At this point, however, all you can enter is a date range.
General Keywords Date Range Geographic Results User Info etc.
This panel allows the user to specify a desired grid and a geographic region of interest on that grid. The defined area will be used for the search and any data requested through the system will be gridded to that subset of the chosen grid.
Caveats: If any of the lat/lon text fields read "NaN" (Not a Number) it means that corner of the rectangle is off the map. This is not necessarily a problem as there are some points on the grid that are off the map.
Many of the grid choices are only subtly different. Since the grid chosen here is the grid the data will be delivered in users should take care to select the right grid. For more information on grids see the page on grid output options.
The zoom choice only changes the size of the grid that is displayed. It has no relationship to the resolution of the grid. Larger maps will slow down the display so we recommend using the smaller maps if possible.
In general the displayed grid is much smaller than the data grid, which places a lower limit on the dimensions of the rectangle that can be drawn. If you know precisely what area you want you should use the text fields.
The grid doesn't always display properly after a new grid is loaded. Until we figure out the problem resizing the window slightly usually fixes it.
General Keywords Date Range Geographic Results User Info etc.
Caveats: Sorting always sorts the entire result set, not just the current page. So if you select some results for order, and then resort, some of your selections may move off the current page. It is recommended that you sort the results the way you want them first, then make your selections.
There is an upper limit on the number of results returned. Currently that limit is 10000 but it could change.
Use caution when making discrete selections. If you do not hold down the <CTRL> button while selecting a row, all of your previous selections will be deselected.
The "Crossing" columns displays the ascending equatorial crossing of the orbit associated with the granule. In general granules with crossings near the min or max of the crossing range will be a poor match for your area of interest.
The "Quality" column is an estimate of how much of the data that should be in the granule actually is in the granule. Granules with a low quality percentage have a lot of data gaps and may not include data that actually covers your area of interest. The quality estimate is not an estimate of how well the granule covers your area of interest. Even granules with a high quality percentage may not cover your area of interest terribly well.
General Keywords Date Range Geographic Results User Info etc.
This panel allows you to specify the data format you would like, and to enter your contact information.
Caveats: If the order submission fails for some reason, the interface is not reset. If this happens you should contact NSIDC User Services. If there are any error messages in the java console window, please provide them with that information.
