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Introduction

The Graphical Interface for Subsetting, Mapping, and Ordering (GISMO) tool is a web-based interface for ordering gridded data from NSIDC.

The GISMO project draws heavily on work done by Naim Alper for the Naval Research Laboratory's Master Environmental Library (MEL). To find out more about MEL, visit its home page.

A big difference between MEL and the GISMO is that GISMO is written entirely in Java. This includes the database interface which is written in Java using the Java DataBase Connectivity (JDBC) protocol.

General Keywords Date Range Geographic Results User Info etc.

General Help

This applet allows you to construct and submit a query based on temporal coverages of the data and the keywords contained in the metadata.

Two rows of buttons at the bottom of the GISMO allow you to navigate between panels and perform various functions that are common to all the panels in the GISMO. You can get help on each individual panel by navigating within this page.

The buttons at the bottom of the applet achieve the following:

• Keywords: opens the Keyword panel. GISMO opens with the Keyword panel by default. You can use this panel to select a collection and one or more corresponding parameters to search for. GISMO was designed to allow a user to select multiple parameters, but not multiple data collections.
• Date Range: opens the Date Range panel. You can use this panel to specify the date range for the data you are interested in.
• Geographic: opens the Geographic area selection panel. You use this panel to specify the geograhic area you are interested in. In most cases the data can be geographically subsetted before delivery.
• Search: submits the query and displays the Results screen. Please note that this may take some time and there is currently no indication that the query is active other than that this button becomes inactive.
• Results: opens the Results screen which displays the search results and prompts a user to select individual granules for delivery.
• Reset This: restores the default values for the currently displayed screen.
• Reset All: restores the default values for all screens.
• Help: displays the Help page.

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.

Keywords Help

The Keywords panel is the first panel to display in GISMO and allows the user to specify a collection and parameter(s) to search for within that collection. The user may select only one collection but may select one or more parameters for that collection. Parameter choices appear in the text area at the top of the screen.

• Text Area: Displays a list of selected parameters.
• Collection List: Allows the user to select a single data collection to search.
• Parameters List: Allows the user to select one or more parameters to search for.

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.

Date Range Help

This panel allows you to specify a temporal coverage for a search. The top Range Panel (labeled "Date Range") allows you to set the overall date range for the search. The middle Range Panel (labeled "Day of Year") allows you to set the annual period for the search. The choice widget allows you to set the daily frequency of the search. And the last Range Panel (labeled "Time of Day (GMT)") allows you to set the daily period for the search.

In the image above the interface will search for data between 1977 and 2002, but only in Winter (12/21 - 3/21), and only in early morning. Moreover, within the annual period the search will only retrieve data from every 7th day.

The three Range Panels provide the following functionality:

• Range Slider: Allows the user to specify a min and a max by sliding one of the two thumbs. The value in the corresponding text field is updated as the slider thumb is moved.
• Text Areas: Allows the user to input a start and stop (min and max) in the specified format. When the cursor moves out of the text field, or the "enter" key is pressed, the slider values will be updated.
• Zoom Button: Zooms the slider so the current minimum and maximum are on the edges. This makes fine adjustments of the slider thumbs a bit easier.
• Shift Button: Shifts the slider to the right by the current minimum value. This allows entering ranges that span the year or day boundary.

• Frequency Choice: Allows the user to specify the frequency of the search in days starting from the first day of the annual period. The text field is editable so values not in the drop down list can just be entered.

Caveats: Leap Day is ignored, and annual periods are searched by day of year, not date. This means that dates after leap day, during a leap year, will get pushed back by one day. For example: The search shown above will search for data from 12/21 to 3/21 during non-leap years and 12/21 to 3/20 during leap years. If you want to be sure you get data from 3/21 during leap years you should extend the range to end on 3/22.

Similarly a search on Summer (6/21 - 9/21) will search for data from 6/21/ to 9/21 during non-leap years and 6/20 to 9/20 during leap years. If you want to be sure you get data from 9/21 during leap years you should extend the range to end on 9/22. If all this is too confusing just follow this rule: "Always pad annual periods by an extra day at the end."

You need to be careful to enter values into the text fields in the specified format. Some other formats are allowed, but we couldn't predict, or compensate for, every possible format. Invalid entries will be replaced by the last valid entry.

The "Shift" button shifts the slider to the right by the current minimum value, so set the minimum before you try to shift the slider. If the current minimum is the same as the slider minimum "Shift" will do nothing.

If you wish to input a range that spans the year or day boundary you must "Shift" the slider even if you are entering values in the text fields and not using the slider at all. The slider and the text fields are linked, so text input has to be validated against the slider.

Once you zoom the slider you cannot zoom it further. You can, however, make your adjustments, unzoom, and then rezoom on the new range.

General Keywords Date Range Geographic Results User Info etc.

Geographic Subsetting Help

This panel allows you to specify a geographic subset for the data you need. Since every granule in each collection covers the entire area the geographic parameters are not actually part of the search criterion, so specifying a geograhic area of interest will not influence the number of granules returned by the search. It will, however, reduce the total size (in bytes) of the delivered data.

• Grid: Displays a grid of the coverage area of the currently selected collection in a new window and allows the user to draw a rectangle to indicate an area of interest. Click-hold-and-drag on the grid to define a region. Shift-click inside the defined rectangle to move the rectangle around. Click-and-hold near a corner to grab that corner and stretch the rectangle.
• Show/Hide Grid: Toggles the grid display. If you lose track of the grid window hitting this button twice (Hide then Show) will bring the grid window to the foreground. If you have iconified the grid window it will remain iconified.
• Status Area: Displays help and status information specific to this screen.
• Selected Grid: Displays the name of the grid for the currently selected collection. You cannot use this widget to change the grid selection on this screen. To select a different collection return to the Keyword panel.
• Zoom Choice: Allows the user to choose the zoom level for the selected grid. Larger grids require more memory and can bog down the interface. The zoom choice does not work on SGI's.
• Lat/Lon Text Fields: Display the latitude and longitude of the corner points (Upper-Left, Upper-Right, Lower-Right, Lower-Left) of the user defined rectangle on the grid. These fields are editable so users may input values. The interface will adjust the input values to the center of the nearest grid cell.
• Lat/Lon Display: Displays the latitude and longitude of the current position of the mouse pointer.
• Row/Col Text Fields: Display the row and column of the corner points (Upper-Left, Upper-Right, Lower-Right, Lower-Left) of the user defined rectangle on the grid. These fields are editable so users may input values.
• Lat/Lon Display: Displays the row and column of the current position of the mouse pointer.

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 neccessarily a problem as there are some points on the grid that are off the map.

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.

Results Help

• Page Status: Displays the page number and subset of results currently displayed.
• Column Headers: Display titles for the information in the column. Click on a column header to sort all the results by that column. <Shift>-click on a column header to sort all the results in descending order. Click-hold-and-drag a column header to move the column. Click-hold-and-drag between headers to resize columns.
• Page Up: The small icon just to the right of the column headers is the page up button. Use this button to go to the previous page of results.
• Results List: Lists the current set of results and allows the user to select granules for ordering. Click on a row to select it and deselect everything else. Click-hold-and-drag to select a range of rows and deselect everything else. Ctrl-click to add a row to the current selection set. Ctrl-click-hold-and-drag to add a range of rows to the current selection set. Shift-click to add the range of rows between the last selected row and the current one.
• Page Down: The small icon just to the right of the horizontal scrollbar is the page down button. Use this button to go to the next page of results.
• Select All: Selects all granules in the entire result set unless it exceeds the maximum request limit.
• Deselect All: Deselects all granules in the entire result set.
• Select Page: Selects all granules on the current page unless it exceeds the maximum request limit.
• Deselect Page: Deselects all granules on the current page.
• Submit: Saves the list of granules the user has selected for ordering and displays the User Info screen.
• Selection Status: Displays the number of currently selected granules and the estimated total size of the request.

Caveats: Sorting always sorts the entire result set, not just the current page. So if you select some results for order, and then resort them, 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.

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.

General Keywords Date Range Geographic Results User Info etc.

User Info Help

This panel allows you to specify the data format you would like, and to enter your contact information.

• Media and Format List: Allows you to specify the media type and format in which you data should be delivered.
• Name Text Field: Enter your name.
• Email Text Field: Enter your e-mail address.
• Done: Completes the order and resets the interface.

Caveats:What media and data formats are shown in the list depends on the requests. If the estimated compressed size of the request exceeds the ftp site limit (500 Megabytes) ftp pickup will not be an option. If the subset area exceeds 64 grid cells ASCII output will not be an option.

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.