Physical Sciences Division

Data is taken from various datasets including the Arkix-Xie data and the NCDC US climate division data.Reference for the dataset on on the left side of the distribution page for that dataset. Resolution for the Arkin-Xie data is about 2.5x.25 degrees,

For each "location", the values for each year are computed and sorted. Depending on the output chosen, they can be binned or some value can be compared to the range. In all cases, the statistics of the data for the year range chosen is calculated.

For each gridpoint, the following statistics were calculated. Note that xbar is the mean for all years used and N is the total number of years.

Mean

The mean is the average value for the averaging time period (month, week, etc.) for the full set of years; usually 41.

STD

The Standard Deviation (STD) is calculated over the full set of years (usually 41) using the equation

sigma=[(sum(x_i-xbar)**2)/(N-1)]**.5

It is a measure of the average departure from the mean.

Skewness

Skewness is the degree of asymmetry of the distribution. It is calculated using the equation

skewness=[sum((x_i-xbar)**3)/N]/ [(sum(x_i-xbar)**2)/N]**(3/2)

Positive skewness has a longer tail to the right.

Kurtosis

Kurtosis measure how peaked the distribution is. A higher number is more peaked than a lower number. It is calculated with the equation

kurtosis=[sum((x_i-xbar)**4)/N]/ [(sum(x_i-xbar)**2)/N]**2

A "normal" kurtosis is 3.

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, computes yearly values and then sorts the data. Plots are done in Gnuplot version 4.

You can use the plots produced from this page in publications. We ask that you acknowledge the Climate Diagnostics Center in the publication. For example, "Image provided by the NOAA-CIRES Climate Diagnostics Center, Boulder Colorado from their Web site at http://www.cdc.noaa.gov/".