Climate: The classical period is 30 years
What is Climate?
Climate in a narrow sense is usually defined as the “average weather,” or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.
— WMO / World Climate Programme / Commission for Climatology / FAQ
While thinking about appropriate windows for the lowess smoothing, I recalled the commonly used definition of climate as a 30 year average. That would seem to lead to a lowess smooth of roughly f=.26 (given a time span of 117 years). Now, I don’t understand the actual windowing used by the R lowess, but if the above is about right to get what is effectively a 30 year window, then we have this …