# Information about the Atmospheric Variables Plotting Page

**Date:**- Default date will be the last date available; usually yesterday
or today (if late in the day) for the NMC data. For the other
datasets it depends. The date represents the last day of the time
period for the specified number of days except for the Reynolds SST
data, where the date is the first day of the last week requested.
The NCEP daily analysis is generally available from 1980 onwards.
The OLR data are available from 1974-
**Nov 30 1998**. The MSU precipitation data are available from Jan 1979-Oct 1996. The Reynolds SST is weekly and is available from Jan 1990-about 1 week before the current date. Longterm means are based on 1985 to 1996. **Number of days**- The number of days should be either the number of days that go into an average for daily data or the number of weeks for weekly data. The more days, the longer the plot will take. Reynolds SST climo or anomaly plots will take even longer because the climatology data is daily. The default number of days or weeks is 1. The maximum number of days allowed is 366.
**Variable:**- Most variables are from the NMC daily operational analysis dataset. The exceptions are the OLR which is from the interpolated OLR dataset, the SST which is from the Reynolds weekly SST dataset, and the precipitation which is from the MSU precipitation dataset. All data are daily except for the Reynolds SST which is weekly. The Eddy geopotential heights are derived from the NMC heights and are computed by removing the zonal mean at each latitude for each day of the requested date range of the data. The vector winds are computed by calculating the average u and v for the time period and then plotting the magnitude and direction of these wind components
**Plot type**- There are 3 plot types. The "Mean" plot represents the average of the variable selected for the time period selected. The "Climo" is the 5 day smoothed (2 days before to 2 days after) yearly long term mean average for the data (except for Reynolds SST, which is a simple 7 day average). "Anomaly" is the "Mean" value minus the "Climo".
**Projection**- There are 5 projections plus a custom projection. They are
defined as follows:
**Northern Hemisphere**: 0-90N, 0-360W in using a polar stereographic projection

**Globe**: 90S-90N 0E-360W

**United States**: 20N-65N; 235-285 polar stereographic projection

**Tropics**: 60S-60N

**Indio-Pacific**(20S-20N,60E-160W)

**Custom**: Choose your own (specify lat/lon boundaries from S-N and E to W) **Custom:**- Specify latitude and longitude ranges. If you need a plot to span the the dateline, you can specify the eastern boundary to be greater than 360. For example, plot from 180W eastward to 180E, you can specify 180,540 for the longitude ranges.
**Color scheme**- Information will go here when I figure it out.
**Labels**- Contour labels will be drawn if
*yes*is chosen. The default is*no*.