This program plots time series of monthly total
precipitation, or monthly average temperature, based on divisional
climate data for the U.S.
The user selects the quantity (precipitation or temperature) and the beginning and ending year (begins with January of the beginning year and ends with December of the ending year). Generally, periods of 10 years or less are depicted the best. Longer periods tend to be difficult to interpret.
For plotting purposes, the data are plotted on the ending year and month of the specified interval.
The individual months are shown by red X's and lines.
The running mean is simply the average of the selected number of months centered on the plotted month. An odd number of months will be plotted centered on an actual month, and an even number of months will be plotted in between month values (for example, the 12-month mean for points from January 1996 through December 1996 will be plotted in mid-June 1996). Although individual months before January of the beginning year aren't shown, they are used to determine the running mean if they exist. For example, if 1990 is selected as the beginning year and a 12-month running mean is also selected, the mid-January running mean begins with data in July of 1989.
The running means are shown as blue X's.
The long term monthly average, if selected, is shown as a series of green crosses connected by green lines. Naturally, these points will be a repeating cycle each 12 months.
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... back to SPI table.
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