Details and instructions on the 3-Hourly NARR Compositing Page
Page will plot maps of selected variables. Select desired options and hit "create plot". Most options have a default setting so a selection is not required. Default for year is last year/month/day/hour available for dataset. You can select one or more dates to composite, variable, level, map color, map location and contour interval/range. If you have problems, please email with ALL the options you chose.
Please read ALL the instructions. Failure to do so may lead to misinterpretation of results.
- Variable, dates and levels available
Data is available from Jan 1979 to 2004 for most variables.
- Enter Dates
- Enter Range of Dates
- Lagged composites
Selecting a nonzero value for this will allow you to do a lagged composite. The dates are determined from one of the date entry methods above. Then, a composite is made N hours before the dates you selected (-N) or after the dates you selected (N). If lagging results in a date that is not in the range of the dataset, that date is not used.
- How the composite is calculated
The composite represents the average of the variable for all dates entered.
- To rotate polar
To rotate map, choose "custom" map projection and then choose either northern or southern polar stereographic projection. For lat range, enter 0 to 90 (for northern hemisphere) or -90 to 0 for southern. For longitude, the center of the longitude range input will be at the bottom of the plot. To center along 0E, choose -180 to 180, for example. To center at 90E, choose -90 to 270. You can plot sectors as well. The longitudes -90 to 90 in the NH will plot the half hemisphere from the US across the Atlantic to Europe.
- Type of Plot
- Plots are averages of dates that are input.
- Contour range/interval option
A desired contour interval and range can be input instead of the default being used. Different plots can be easily compared (and the resulting gifs could be animated). For this option to work, the interval AND the range must be input. There must be at least 2 and less than 33 contours. The contour interval must be positive and the range must go from low to high.
- Black and White Option
You can select black and white contours and shading for printing on noncolor printers or monitors..
- Plotting Regions
To plot over the dateline, use values from 0 to 720. For example, to plot 180W eastward to 180W, use 180 to 540. Be sure that the western most longitude is less than the eastern., For example, to plot 100W to 70W, use -100 to -70 or 260 to 290 and NOT 100 to 70.
There are 6 custom projections:
Arctic NARR: polar stereographic projection
United States: 20N-65N; 235-285 polar stereographic projection
Lower 48 USA:
- How this page was created
The main interface for this page is an html form. The data that are input into this form are processed by a Perl script. The script reads the inputs, tests for bad inputs and then executes a FORTRAN code that produces a composite file (in netCDF). This file is what is processed by a GrADS script. The GrADS script is run as a batch job. Plot options are input into the GrADS script. The plot in the frame buffer is converted to gif and this gif is displayed as part of a html document. The netCDF file and the gif file are kept in a directory where the files are periodically deleted.
Please let me know if find the page useful. Likewise, let me know if you think any instructions are unclear, if you think there are bugs or if you have any suggestions for improvements of any type. We would particularly like to know if you use these pages for teaching purposes and if so, how. I can be reached by email at firstname.lastname@example.org.