This image is a "Contour Map", which is generated from a query. The image is from the UV-B Monitoring Program, a division of the United States Department of Agriculture so is "public domain" and can be accessed by anyone with a web browser.
Sums Contour Maps
Daily sum values represent an integration over time. Basically by summing the readings over the number of seconds in the measurement period, the units of radiant power are converted to radiant energy and are useful for studying daily effects related to daily exposure. Current available values are Caldwell biological spectral weighting function, Flint biological spectral weighting function, erythemally weighted irradiance, UV-A irradiance, UV-B irradiance and Vitamin D. Similarly, it is also possible to view the sums of biologically weighted indices over monthly or annual periods from selections on this page.
Contour graphs of the data are available for any time selection. The graphs will be displayed along with a tabular view of the data used to create the graphs. We also provide a feature to export the data to a file on your local computer in a comman delimited(CSV) format.
This work is in the public domain in the United States because it is a work of the United States Federal Government under the terms of Title 17, Chapter 1, Section 105 of the US Code. See Copyright.