EDUCE IGF PAS PARTICIPATION WPX1 ESTIMATE OF THE NATURAL LEVEL AND VARIABILITY OF SURFACE UVR OVER POLAND J.W. Krzyścin, J. Borkowski, J. Jarosławski, and P. Sobolewski Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland

Retrieval of Aerosol Optical Depth from the UV Direct Sun Intensity Measured by the Brewer during total ozone calculation procedure The method uses the Langley plot estimation of extraterestrial constants article in press J.Geophys.Res.

Ǻngström Formula: Aerosol Optical Depth = Visible range α = 1.3  0.6 Ǻngström Exponent α versus AOD at 320 nm for selected pair of wavelength α < 0 ! →

Comparison of the surface irradiance and actinic flux at 310 nm by LibRadtran model for various input: -full input (total ozone-Brewer, ozone profile-Dobson Umkehr, temperature-rawind sonde, AOD-Brewer, SSA+ phase function-CIMEL, -classic input (total ozone-Brewer, standard profiles for NH midlatitudes, AOD at 550 nm-CIMEL, Ǻ ngström Exponent=1.3, rural aerosol model) Biomass burning ←

Biometr Irradiances (SL 501A) for the period Belsk SZA=60 0

Ozone Vertical Profiles by Umkehr Observations

Partial Radiation Amplification Factors (RAF), , for ozone profile impact on UV and Radiation Amplification Factor due to aerosol,  Model applied for broadband irradiances taken at SZA=60 and 80 by SL501 A over Belsk for the cloudless period Partial RAFs depend on SZA UV more sensitive to ozone content in upper levels for large SZA RAF due to aerosols almost constant

Our Findings Brewer Spectrophotometer – instrument providing spectral aerosol optical depth No long-term aerosol forcing on the surface UV at Belsk Aerosol properties in the UV range can not be extrapolated from those in the visible range Partial Radiation Amplification Factor (RAF) due to ozone changes in selected Umkehr layers depend on SZA - empirical evidences for the ozone profile impact on UV. Significant impact of day-to-day changes in aerosols on UV irradiance – RAF due to aerosols ~0.12 (weak dependence on SZA)

EDUCE IGF PAS PARTICIPATION WPX1 EXAMINATION OF SURFACE VARIABILITY AT DIFFERENT TIME SCALES IN SURFACE UVR METHOD FOR RECONSTRUCTION OF UVR TIME SERIES AT EUROPEAN SITES

MULTIRESOLUTION DECOMPOSITION OF THE DATA SERIES USING WAVELETS. The wavelet expansion of a time series f(t) enables us to perform a multiresolution decomposition, which separates the series into components: f(t)=S J (t)+D J (t)+D J-1 (t)+…….. D 1 (t). where functions S J and D j (t) are called the smooth and detail components respectively. The advantage of wavelet methods is that wavelets provide exact scale-based decomposition results, and can be applied for nonstationary processes.

Our Findings: Components of the wavelet multiresolution decomposition represent variations at time scales from 2 to 64 months and „smooth” variations UV responds differently to ozone and cloudiness variations at different time scales Modeling different components separately results in good agreement between modeled and observed values particularly for longer time scales The smooth component can be perfectly reconstructed with ozone and cloudiness as explanatory variables only

Annales Geophysicae, 2003, 21, Non-linear (MARS) modelling of long-term variations of surface UV-B radiation:As revealed from the analysis of Belsk, Poland, data for the period Regressors: Belsk’s Dobson total ozone, Cloud cover from NCEP/NOAA Reanalysis, Teleconnection Indices (QBO+NAO+ENSO). 11-year solar cycle Regressors: Belsk’s Dobson total ozone Total solar radiation from Belsk’s pyranometer Teleconnection Indices (QBO+NAO+ENSO) 11-year solar cycle ↕ ↕

Comparison the model-observation simulation of the interannual changes in the UV data BELSK: Monthly means for May-October subperiods in The simplest modelThe most sophisticated model  

Our Findings Nonlinear Regression Model-MARS resolves larger part of month-to-month variations but small improvement of the long-term fit to the observed UV radiation Long-term Cloud Effects from Reanalysis-1 Data Base – UV reconstruction for any site (if ozone data available) NAO and SOI effects on UV by MARS model (impact on atmospheric optical depth over Belsk)

EDUCE IGF PAS PARTICIPATION WPX1 Verification and Extension of UV Climatology at Selected European Sites

Objectives  Belsk  Toravere  Hradec K. - Calibration - UV Doses Climatology - Long-term Changes of UV dose - Clouds and Total Ozone Effects on UV Doses long-term changes Results based on the article submitted to Journal Geophysical Research

Model Verification CRF –Cloud Reduction Factor IGF PAS model: RIVM model: Gl - measured daily sum of total solar radiation Gl*- modelled clear-sky sum of total solar radiation 2

UV-Climatology

Long-term UV variations from the reconstructed UV data Hradec Kralove (April-September) Monthly UV doses UV daily doses –clear skies Monthly UV doses cloud effects Monthly UV doses – ozone effects

Our Findings: Reconstruction of the UV time series from historical time series of total ozone and global solar radiation Delineation and correction method for the instrument drift in historical time series of global solar and UV radiation Establishing the UVR climatology for Central Europe (seasonal profile of UVR and the clouds forcing on UVR ) Estimations of the clouds and total ozone long- term effects on the surface UVR since mid 1960s

EDUCE IGF PAS PARTICIPATION WPX2 Estimation of trend variability in Belsk at least 2 other sets

I. There is no precise, commonly accepted definition of a trend. II. Pristley [1981] refers to trend as “…tendency to increase (or decrease) steadily over time” Kendall [1976] -“the essential idea of trend is that it shall be smooth”. III. Most popular approach y(t)=C*t +e(t) C depends on time period considered, and does not show variations of the trend within the time period TREND DETERMINATION

WAVELET APPROACH 1.The „smooth” component of the signal is extracted with the use of wavelet multiresolution decomposition 2. Trend is defined as time derivative of the smooth component of the signal.

Conclusions: Trend is function of time Trend determined from smooth component is not contaminated by fluctuations with short time scale The problem of the influence of the kind of wavelets on trend is beeing investigated

EDUCE IGF PAS PARTICIPATION WPX3 Submission of spectra and broad-band measurements The data sets from Belsk in the UV data base: The UV spectra from the Brewer spectrophotometer ( ~ spectra) Erythemal irradiances by SL 501A biometer (resolution 5 minut) – Global Solar irradiances by CM1 pyranometer (resolution 5-minut) – Total ozone from the Dobson spectrophotometer (daily representatives )