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(the annual /1997/ report on grant project of GA CR 205/96/1554)
Martin Dubrovsky
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(i) Interstation correlations among selected daily characteristics (sums, daily maxima of 10-minute sums, daily maxima of hourly sums) are within (0.87, 0.90). The correlations are quite stable during the period 96/XIII - 97/VII apart from several brief periods. This may be explained by variability of circulation conditions, and possibly partly by some drop-outs in Milesovka's measurements.
(ii) The special stress was put on comparison of daily courses of UV-B radiation on sunny days. It was found, that the fit between the daily cycles at the two locations are nearly perfect (See Fig.1 for an example).
With use of multiple linear regression, the dependence of UV-B radiation on total ozone and solar zenith angle was studied. Only sunny terms (based on sunshine records) were selected for this purpose. Radiation Amplification Factor (RAF) is defined as RAF = dlnE/dlnTO (E relates to UV-B radiation, TO is total ozone. The value of RAF determined from measurements in Milesovka and Hradec Kralove was found to lay within <0.9,1.25> (Fig.2). The correlation between total ozone and UV-B radiation is higher in Hradec Kralove, which may be explained by higher quality of data from this station (the UV-B measurements has started no sooner than in 1996 in Milesovka!).
Fig. 1. Daily cycle of 10minute sums (thin lines) and hourly sums (thick lines) of UV-B radiation in Milesovka (dashed lines) and Hradec Kralove (solid lines) during a sunny day (15.5.1997).
Fig. 2. The dependence of the Radiation Amplification Factor (RAF) on a solar zenith angle (ZA). The values of RAF were determined by a bilinear regression analysis using regression function lnE = a + RAF.ln(TO) + c.ZA where E is a 10minute sum of solar UV-B radiation, TO is a total ozone, a and c are regression coefficients.
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