Topics of interest in solar UV measurements

1. Topics of interest in solar UV measurements Berit Kjeldstad Norwegian University of Science and Technology, Norway Gunther Seckmeyer University of Hanover, Germany

2. Contents • Combined action in UV measurements: EDUCE project • European UV data base • Quality assurance at the database • Climatology and Trends • Users requests for UV data

3. European Database for Ultraviolet Radiation Climatology and Evaluation Coordinator: Prof. Dr. G. Seckmeyer (University of Hanover, Germany) http://www.muk.uni-hannover.de/EDUCE EDUCE

4. EDUCE is a continuation of research activities performed within SUVDAMA Scientific UV DAta MAnagement Participants16 contractors and 9 subcontractors from 15 European Countries Duration June 2000 – November 2003 Supported by European Commision Part of the Atmospheric UV Radiation (ATUV) cluster at the European Ozone Research Coordinating Unit

5. Objectives • To establish a UV climatology for Europe in combination with investigations into potential long-term changes in the UV radiation environment • To continue the collection and storage of UV radiation and ancillary data in the European UV database, providing a comprehensive database of measurements together with the software tools needed for efficient search and retrieval of data • To control and assess the quality of the data in the database • To develop, test and implement radiative transfer models, which are the primary tools in both the study of the UV environment and the quality assurance of the measurements

6. EDUCE: European Database for Ultraviolet Radiation Climatology and Evaluation Coordinator: Prof. Dr. G. Seckmeyer (University of Hanover, Germany) Project Management

7. The European UV Database contained in June 2003: • Data from 34stations in Europe • 45 000 measuring days • 1,4 Million spectra • 24 Gbyte from the submitted files • Available for everybody if you register at the EDUCE web page.

8. Database WEB page • submission (flexstore format) extraction of spectra from all stations • BASINT software tool to explore the contents of the European UV Database and extract information on the ultraviolet spectral irradiance and (Erythemal dose rate) • Reports • Quality control of waveelength shifts, level of irradiance,spikes and spectral anormalities, transmission • Topographical maps • Metadama • site description

10. BASINT tool Back

11. QA at the database Back

12. Quality control at the database: • Colour flags indicate the quality: • GREEN spectra meet WMO/EDUCE criteria; no significant error found (normal range for transmission) • YELLOW small error / deviation identified • RED significant error / deviation identified (questionable use; or exceptional situation • BLACK bad quality (normally not retrieved; or extreme situation) • GREY no decisive result obtained (BLACK flags turn GREY at low irradiance(< 5 10-4 W/(m2 nm))

13. QUALITY FLAGGING SHICrivm software package RIVM • wavelength scale error => shift (FLAG) • detection limit; lowest irradiance level => start_irradiance (FLAG) • spectral anomalies • spikes (correction of spikes with factor 2 relative shape errors possible) => spike+local_shape (FLAG) • distortion of spectra/variable conditions during scans • cloud effects => scan_variability_2 (indicator) • irradiance scale: cloud transmission spectrum trans_2 (FLAG) • clear sky (indication of extremely high or low values) • cloudy sky (cloud transmission estimate) • summary of quality parameters (statistics and colour flagging) • deconvolution, effective UV, common slit analysed spectrum (instrument intercomparison)

14. FLAGS: green, yellow,red,black • wavelength scale: • shift_1 300-325 nm • shift_2 325 - 400 nm (315 - 325 nm) GREEN < 0.1 nm < YELLOW < 0.2 nm <RED <0.4 nm BLACK • start_irradiance_flag • GREEN<0.0005 W/(m2 nm) <YELLOW < 0.0015 < RED < 0.005 < BLACK • spike+local_shape_flag • model and measured (ratio two nearby irradiances) • transmission_2 (325 – 400 nm) • model clear sky and measured • GREENratio clear sky/measured (1.25 – 0.1)

15. Format of Analysis • Extent of annual coverage : potential use • Categorization of quality of overall dataset • Calibration of instrument versus ET solar spectrum • Distribution of flags in dataset

18. Overall results for shift_1: (300-325 nm) 1 million spectra

19. Overall results for spike_and_local_shape flagging

20. Topographical map

21. Topographical maps (NILU) Metadama UMIST Description of the site Surface description Environment (mountain, coast, field land....) Horizon Measurement regime

22. Preliminary results on UV climatology Objective:To construct climatological UV maps from EDUCE database (LAP and RIVM) Additional information: TOMS data and Pyranometer data

27. Trend analyses –Two stations with 11 year of data Number of years needed to see a trend. Optimal wavelength to observe a trend

28. Number of years required for trend detection • Each point is an average of all analysed solar zenith angles

29. Results • Thessaloniki: After 15 years a UV increase due to an ozone trend of -4.5 % per decade should be detectable • Sodankylä: After 11 years at the earliest a UV increase due to an ozone trend of -5.7 % per decade should be detectable • Sodankylä: If there would had been such an ozone trend in the analysed period it would have been recognised in the UV time series.

30. A database for whom ?USERS NEEDSwhat kind of data and information do you need?

31. Data products requested

32. Daily UV dose

33. Weighting functions

34. Search tools

35. Quick userfriendly model

37. Co-ordinator: Prof. Gunther Sechmeyer (University of Hannover, Germany) Prof. Berit Kjeldstad (NTNU, Norway) Dr. Erich Putz (UG, Austria) Dr. Petteri Taalas (FMI, Finland) Dr. Brian Gardiner (BAS, UK) Prof. Alkis Bais (LAP, Greece) Dr. Harry Slaper (RIVM, The Netherlands) Dr. Arve Kylling (NILU, Norway) Dr. Ann Webb (UMIST, UK) EDUCE PIs

38. EDUCE PIs (continued) • Dr. Philipp Weihs (BOKU, Austria) • Dr. Ola Engelsen (NPI, Norway) • Dr. Mario Blumthaler (UI, Austria) • Prof. Jacqueline Lenoble (UJF, France) • Dr. Michal Janouch (CHMI, Czech Republic) • Prof. Janusz Borkowski (IGFPAS, Poland) • Dr. Kalju Eerme (TO, Estonia) • Dr. Zenobia Litynska (IMWM, Poland)

39. EDUCE PIs (sub-contractors) • Dr. Dider Gillotay (IASB, Belgium) • Dr. Alcide Giorgio di Sarra (ENEA, Italy) • Dr. Uwe Feister (DWD, Germany) • Dr. Manfred Steinmetz (BfS, Germany) • Dr. Julian Gröbner (JRC, Italy) • Dr. Anna Maria Siani (URO, Italy) • Dr. Diamantino Henriques (IM, Portugal) • Dr. Michiel van Weele (KNMI, The Netherlands) • Dr. Colette Brogniez (USTL, France)

40. EDUCE group Bordeaux France 2002

41. Future challenges in UV instrumentation and research

42. Needs for Improving Data Quality • More reliable and more accurate calibration sources • Built-in Quality Control • On-line wavelength checks in all instruments • More frequent radiometric stability tests • Design and operation of instruments according to WMO guidelines • Accurate Non-scanning instruments • Ref: G.Seckmeyer et al. Instruments to measure solar ultraviolet radiation. WMO-GAW report No.126, 2001.

43. Thank you for your attention ! For more information go to:http://www.muk.uni-hannover.de/EDUCE