1Ts. Gogosheva, 2B. Mendeva, 3B. Petkov, 4D. Krastev

В данной работе представленео исследование динамики солнечного УФ - излучения и поведения общего содержания озона (OCO) над Болгарией в период с 1996 по 2005 г . Данные измерений получены на спектрофотометре Photon, распо ложенном в Стара Загора . Мы также применяем данные по озону со спутниковых экспериментов TOMS. Анализ данных показывает , что :

• –    за последние 10 лет над Болгарией не выявлено статистически значимой тенденции поведения OC О ;

• –    наибольшие вариации OC О происходят зимой и весной , а наменьшие – летом ;

• –    уровень достоверности сильной зависимости между солнечным УФ - В - излучением , достигающим поверхности Земли , и OC О (r =–0.62 ± 0.18) составляет 98 %.

This paper presents an investigation of the solar UV radiation dynamics and the total ozone content (TOC) behaviour over Bulgaria in the time period 1996–2005. The data are received from measurements, using the spectrophotometer Photon, placed in Stara Zagora. We also use ozone data from satellite experiments TOMS. The data analysis shows:

• –    there isn’t a statistically significant TOC trend over Bulgaria in the last 10 years;

• –    the largest TOC variations are in the winter-spring and the lowest – in the summer;

• –    a strong dependence between UV-B solar radiation reaching the Earth surface and TOC is received (r = –0.62 ± 0.18) at 98 % confidence level.

  Data analysis and results

  The dynamics of the total ozone content over Stara Zagora is investigated using data from TOC measurements by the ground-based spectrophotometer Photon (1999–2005) as well as by the satellite instrument TOMS-EP (1996–2005).

  The variability of the TOC monthly mean values, measured by TOMS-Nimbus-7 (1979–1992) demonstrates a negative trend (–6.9 %) in the TOC course [1]. Using data from TOMS-EP we receive that for 1996–2005 there isn’t a statistically significant TOC trend over Bulgaria (Fig. 1). Similar results for this time interval are obtained by Varotsos for latitudes of 62.5° S [2] and by Semenov for 42.6° N [3].

  Using the TOMS data for 1996 – 2005, we track the TOC variations for the separate months of these years. The largest ozone fluctuations are in the winter-spring months of all years, and the lowest – in the summer months (Fig. 2). This might be due to the enhanced dynamics of the Earth’s atmosphere in the spring.

  The intensity of UV-B solar radiation reaching the Earth surface strongly depends on the total ozone. Fig. 3 shows instantaneous values of solar UV irradiance at 305 nm measured at 30° SZA together with the total ozone. Reduction in the ozone leads to an increase of these wavelengths. The inverse relationship of these two variables is significant (r = –0.62 ± 0.18) at 98 % confidence level.

  TOMS

  3³0⁵0⁰ лМдДлМЛ

  96     97    98     99    00    01     02    03     04    05

  Years, 1996 - 2005

  Fig. 1. TOC course from TOMS-EP data.

  
  
  
  
  
  
  
  

  о 370

  
  

  О 350 о 330

  
  
  
  

  TOC 1997-2005 TOMS-EP

  
  
  

  ²⁵⁰1996   1997   1998   1999   2000   2001   2002   2003   2004   2005   2006

  
  

  Years

  
  

  Fig. 2. TOC monthly average values for February( ○ ) and July ( ■ ) using TOMS-EP data, 1997–2005.

  
  
  
  
  
  
  
  
  
  

  SZA=30^o 1998-2003

  
  
  

  250         300          350         400         450

  
  

  Total ozone, DU

  
  

  Fig. 3. Dependence of the 305 nm wavelength irradiance on the TOC using Photon data.

  
  

Динамика солнечного ультрафиолетового излучения и озона над Болгарией