Updated 11/04/98
Pollen Percentages
Pollen Percentages: The pollen sum is the standard f70 sum for North America developed for the North American Pollen Database. We use the f70 variables to create pollen percentages, and then average these percentages over a 1000 year interval (+/- 500 of the target age) to obtain the percentage values used in these maps. Rather than show data for all pollen variable, we elect to show maps of twelve key pollen variables.