Directions and details for the WRIT monthly composite mapping page
Variable: Datasets | Variables | Enter Dates (1st dataset) | Enter Dates (1st dataset)
Statistic | Plot Type
Plotting Options: Map
Region Custom Projection | Color/ContoursReverse Colorbar | Contour interval option | Output Type
Information: Page Creation | Feedback | Caveats
Page will plot maps or vertical cross sections of selected pressure level variables and single level variables at a single time or averaged over a set of dates. Users can also difference two datasets (at the same or different time period). Select desired options and hit "create plot". Most
options have a default setting so a selection is not required.
If you have problems, please email with ALL the options you chose.
A plot, the data used to create the final plot (in netCDF), a post script image and information on the dataset will be returned.
Various global reanalyses are provided as well as 2 observational datasets. For the MERRA, we are using the lower resolution data (1.5x1.5). MERRA is not defined for values below the surface (details). All other reanalyses datasets we provide have values for the pressure levels below the surface. Some single level variables are also made available.
- Dataset 2 (optional)
Select "none" or a second global reanalyses. Differences are calculated by interpolating the lower spatial resolution values to higher, if the datasets aren't at the same resolution. Differences for vertical cross sections are calculated using this set of levels that is common to all the
reanalyses we are using: 1000., 850.,700.,600.,500.,400.,300.,250.,200.,150.,100.,70.,50.,30.,10. Cross-section is interpolated from the lower to higher resolution dataset before differences are calculated. For the MERRA, we are using the lower resolution data (1.5x1.5). MERRA is not defined for values below the surface (details). All other reanalyses datasets we provide have values for the pressure levels below the surface.
Monthly data is available for each of the reanalyses for the time period of the reanalysis. Ending dates vary. We plan to keep the datasets as up-to-date as possible. Currently, data is available through at least 2011 for all but MERRA and 20CR (2010) reanalysis datasets. Details on datasets are available.
- Enter Years
Enter positive, integer years. If a year is not in your dataset, you will get an error. Enter the first and last
months of a season. If the first month is greater than the second, the year will correspond to the last month of the season. That is, Dec-Jan 1991 is Dec 1990 and Jan 1991.
- Enter second set of Years (optional)
If you select the same dataset for the second dataset option, you can use the page to calculate the difference between 2 sets of month/year/year combinations. Enter positive, integer years. If year is not in your dataset, you will get an error. Enter the first and last
month of a season. If the first is greater than the second, the year will correspond to the second year of the season. That is, D-J 1991 is Dec 1990 and Jan 1991.
- Variable Statistic
- Plots are the values from the model or observed dataset.
- Long Term Mean (Climatology)
- The long term mean of the variable for a specified month is plotted. We use 1981-2010 where possible. Anomaly datasets may have a different climatology.
- Plots are of mean minus climatology for the variable. Each monthly anomaly is computed separately.
- Plot Type
Map: Latitude by Longitude)
A latitude/longitude plot. Enter longitudes east to west. There are some custom regions provided.
Vertical Cross section: Latitude by Height
A vertical cross section. Plot is averaged over longitudes entered (east to west). Averages are only available for at most 360 degrees.
For a plot at one longitude, enter the same value for eastern and western longitude bounds. Page will use nearest latitudes and longitudes to those selected. Latitudes and longitudes available differ. They are usually points (reanalyses) or centers (observed).
Vertical Cross section: Longitude by Height
A vertical cross section. Plot is averaged over latitudes entered (south to north).
For a plot at one latitude, enter the same value for southern and northern latitude bounds. Use decimal form of degrees. The plot will use nearest latitudes and longitudes to those selected. Latitudes and longitudes available differ. They are usually points (reanalyses) or centers (observed).
- CUSTOM projection (maps)
Cylindrical equidistant (latitude/longitude on same scale) or polar stereographic (northern and southern) are available.
- Color and Shading
You can select either color or black and white for the shading/contours. Contour types are simple contour lines, shade fill or both.
- Scale plot size:
you can increase or decrease the plot size by inputting a percentage between 1 and 200. The default is 100%. Values
outside those ranges are ignored.
- Plot contour labels
Select this to draw contour labels on the contours.
- Override default contour interval?
A desired contour interval and range can be input
instead of the default being used. This enables plots to be compared
or generating images that can be animated. The interval (small to large) AND the range must be input. There
is a limit of 150 contour levels with this method.
- Output type?
The default is a GIF plot. For maps, a user can choose "google earth". For this, a global map is created and put into kmz/kml format. In addition,
for users with google earth browser installed, the map can be viewed in the google map application.
- 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 NCL
is run to read, analyze and plot the data. NetCDF and postscript are also produced.
For Google Earth, kmz and kml files are also created.
The netCDF file, image and other files are kept in a directory
in which 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. I 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 or by phone
at (303) 497-6263.
The plots and data generated from the page are provided as a helpful aide to research. While every attempt is made to assure the plots are accurate, users are encouraged to confirm results, particularly if plots are to be used for publications or similar uses. Both plotting and analysis have underlying assumptions that may impact specific results. The page is not guaranteed to be available as PSD is not an operational center. Data may be updated or changed at the source and therefore replaced at our site. Please check dataset documentation for further information. Please send us any questions about the plots or analysis methods.