Total column ozone and solar UV-B erythemal irradiance over Kishinev, Moldova

Abstract

Results of the total column ozone and ultraviolet (UV-B) erythemally weighted irradiance
 measurements at the ground-based solar monitoring station at the Kishinev (Moldova) are
 presented. Diffuse and global components of solar UV-B erythemal irradiance on horizontal
 plane were continuously measured with sensors UV-S-B-C (of broadband 280-315 nm),
 Kipp&Zonen. Monthly totals of global and diffuse components of solar UV-B erythemal
 radiation reveal distinct seasonal variation with respective minimum in winter and maximum in
 summer. Typical values for these components in limiting cases are presented. A simple
 polynomial relationship between the global and diffuse components of solar UV-B erythemal
 radiation measured for cloudless days was derived. It was shown that coefficients of the
 polynomial depend on daily mean value of aerosol optical thickness (AOT). Collocated
 measurements of AOT have been carried out with the sunphotometer Cimel CE-318 within
 the framework of the Aerosol Robotic Network (AERONET) program, managed by
 NASA/GSFC.
 Total column ozone content was retrieved from direct solar ultraviolet radiation measurements
 at 3 discrete wavelengths centered at 305.5, 312.5, and 320 nm within the UV-B range.
 Ozone measurements were regularly carried out with the hand-held MICROTOPS II
 Ozonemeter, Solar Light Co. Monthly average values of total column ozone content
 measured with the MICROTOPS II at the Kishinev are in close agreement with those ones
 retrieved from the multiyear (1978-2004) database statistics acquired from satellite platforms
 measurements with the Total Ozone Mapping Spectrometer (TOMS). It was shown the
 existence of seasonal variability of the total column ozone content with respective minimum
 values observed at the end of autumn and winter, and maximum values observed at the end
 of winter and in spring. The maximum and minimum of daily mean values of total column
 ozone ever measured with TOMS at the satellite platforms overpassed Kishinev site,
 amounted of ~540 DU (on February 19, 1985) and ~204 DU (on December 1, 1999). Yearly
 mean value of total column ozone measured at the Kishinev was ~ 338 DU. Total column
 ozone measurements carried out with MICROTOPS at the Kishinev site from September
 2003 to August 2004, gave maximum and minimum values of ozone daily means at ~ 489 DU
 (on February 12, 2004) and ~259 DU (on December 3, 2003). The estimation of total column
 ozone trend derived from the TOMS multi-year statistics was ~ -10 DU/decade.