Long-Period Variations of UV-B Radiation From Results of Ozone Reconstruction from Dendrochronologic Data
Zuev, V.V. and Bondarenko, S.L., Institute of Atmospheric Optics Russian Academy of Sciences Tomsk, Russia
Thirteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting
The thickness of stratospheric ozone layer modulates the level of UV-B radiation reaching the surface without cloudiness. The high level of UV-B radiation causes a stress of vegetation including trees. The stress-induced changes in physiologic processes are reflected in tree ring characteristics. The multi-centennial history of ozonosphere behavior is contained in annual tree rings on the basis of response to UV-B radiation effect. The dendrochronologic time series are statistically representative, and are represented by different parameters of annual tree ring width and density for different tree species. It was found that, for stress effect of UV-B radiation on coniferous trees, the wood density is a more sensitive parameter. The total ozone (TO) content averaged over April September is most strongly correlated with mean wood density for spruce; the correlation of this parameter for this tree is about -0.8. It is shown that TO paleobehavior can be reconstructed using TOMS satellite data for any geographic region for which the dendrochronologic data exist. The report presents the results of reconstruction of multi-centennial behavior of total ozone and UV-B radiation for different Canadian regions. The ozone variations have nearly the same period as variations of UV-B radiation, of course differing in amplitude, because intensity of UV-B radiation and ozone are exponentially related. The conversion of TO indices to the indices of UV-B radiation was made using model. The reconstructed and converted data were verified against instrumented observations of UV-B radiation at three Canadian sites.
Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).
