The Live Access Server (LAS) enables you to
LAS has been tested on many, but not all, combinations of platform-operating system-browser. If LAS is not working for you, check to make sure that Java and Javascript are enabled in your browser. If both are enabled and the interface still doesn't work you should use the classic LAS at http://ferret.wrc.noaa.gov/las1/climate_server.
Data served by LAS are inherently multi-dimensional. This means that the data are defined on a grid with axes corresponding to X (longitude), Y (latitude), Z (depth or height) and T (time). A unique feature of this server is that it allows you to decide how the data is sliced up into different views. Then you get to choose which "slices" or "slabs" in this view of the data you want to visualize or download.
We use the term view to refer to a user selected set of axes. Examples would be: T (time line), XY (lat-lon map), XZ (longitudinal depth section), XT (Hovmöller diagram), etc. A list of all possible views is created each time you select a variable and a particular view can be selected from the View menu on the interface.
Once a view has been selected, you can control of the range of data to be displayed. Use the map and the time and depth selection tools in the interface to specify a range or point on the globe and the time(s) and depth(s) you are interested in. These selections will define a region to be used in generation of the output plot or data file.
Once you have defined a region, it will be preserved as you select other data which contain the view axes. This makes it easy to generate graphics or data files that allow you to compare data sets.
Obtaining background material about a
data set
Information about each dataset is available by clicking
on the data set name.
Selecting data
Version 3.x) Select a data set and variable from the
left hand panel. This panel contains a list of the data sets that
are available. Under each data set name is the menu (compact view)
or list (full view) of the variables in that data set. Choose
a single variable from your desired data set. The name of the
data set and variable you have selected will appear at the top
of the right hand panel.
Version 4.x) The left hand panel starts out with a list of data set names. Clicking on a dataset name will expand (collapse) that dataset to show (hide) the variables contained in that data set. Select a variable by clicking on the variable name.
Changing views (geometry)
Select a view for the data with the View selector near
the top of the right hand panel. Data may be viewed along any
axis or any combination of axes associated with a particular variable.
(Note: three and four dimensional output can be downloaded
but not visualized.)
Choosing a region
Select a latitude and longitude region in one of several ways:
Select times and depths with the selectors below the map or type values into the typein fields associated with the time and depth selectors. The typein fields duplicate the functionality available in the selectors: you don't need to enter anything in them. However, the typein fields allow you to enter values in between grid points on the associated axes. In such cases, linear interpolation is used to create data at the desired location. (Note: whenever the typein fields contain a value different from their associated selector, the value in the typein field is used.)
Output
Select the product that you would like (GIF image, comma-delimited
ASCI file, etc.) from the selection list at the bottom of the
right hand panel. If an output image is requested a menu will
appear immediately to the right that allows you to designate the
image size.
Make your request!
You may make your request at any time. Press the Get Data
button to do so. Images and data will created on the fly and returned
to your browser.
Contact us: acacia@ucar.edu
January 18, 2000
Steve Hankin
Jonathan Callahan
Joe Sirott