NCVweb is a data analysis and visualization tool that allows for easy viewing of NetCDF data files made available by the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program. NCVweb is accessed using a Web browser and permits the user to view the contents of ARM data files residing at various ARM data repositories. This tool helps to eliminate the need of and problems associated with downloading large volumes of data, installing and configuring visualization software, or writing custom data exploration software. Unlike generic NetCDF data viewers, NCVweb understands ARM file conventions -- which assists in generating better-looking plots. It does a number of things that would be time-consuming or difficult for users to do themselves -- especially users new to ARM formatted files. These features include: producing a detailed table of file contents (variable names, dimensions, units, and descriptions); detecting and not plotting data points designated as "missing"; generating statistics on the fly, such as min/max, mean, standard deviation, and number of points missing; plotting any set of compatible variables; permitting a user to zoom in on any region within the plot; providing the user a choice for a time axis; displaying the NetCDF file header; allowing for various symbol and/or line combinations; supporting multiple plot sizes to accommodate various screen sizes; generating appropriate plot labels based on the data being viewed, with smart truncation; showing data values in formatted tables; and remembering user preferences from session to session.

In the 2D-plotting mode, NCVweb makes line and/or scatter plots of any two vectors in the data file having compatible dimensions. In the 3D-plotting mode, two-dimensional arrays can be viewed using either 3D color image plots or 2D plots of data slices. All legends and axis labels are produced automatically from information contained within the NetCDF file. NCVweb can be accessed at the ARM Data Quality Health and Status web page (DQ HandS) and at the ARM data archive. The web page at http://arm.mrcsb.com/ maintains a listing of all sites using this utility.