Local (and Not So Local) Weather and Climate

By Barry A. Klinger, George Mason University
Questions and Comments: bklinger@gmu.edu


Not So Local:

For Non-Experts: Some Definitions

Climatology refers to the field of climate science, but within climate science it usually means a data set that has been averaged over a number of years. For example, the climatology of March temperatures is the average of every March during a certain time period (the March temperature for a given year is itself an average of measurements taken twice every day of the month). A standard period for calculating climatologies is 30 years.

Anomaly is the difference of a particular value from bfits climatological value. For example, here the March 2010 temperature anomaly is the difference between March 2010 average temperature and the average of all March temperatures from 1985 to 2014. Unlike in common usage, "anomaly" does not mean "odd, unexpected"--in fact if temperature one year had no anomalies it would be, well, anomalous!

Running mean does not refer to kicking your competitors when in a foot race, but is simply an averaging process that includes times before and after each time. For instance, in a three month running mean, "March 2010" is actually the average of February-March-April 2010, and "April 2010" is the average of March-April-May 2010.

Last modified: 20 February 2019