Coordinating and Integrating UV Observations in Svalbard Georg Hansen & Tove Svendby, NILU, Norway Boyan Petkov & Vito Vitale, ISAC-CNR, Italy Piotr Sobolwski, IGFPAS, Poland Josef Elster, University of South Bohemia, Czech Rep. Kamil Laska, Masaryk University, Czech Rep.
Acknowledgments We thank the Research Council of Norway/ Svalbard Science Forum for funding the UV- ICARE project (Project No: 7644/E) in the frame of the Svalbard Strategic Grant program. We gratefully acknowledge the work of our colleagues, including station engineers, in gathering long-term data series.
The UV-ICARE project Geographic position of the stations measuring solar UV irradiance and total ozone at Svalbard. - Continuous interest in the atmospheric ozone layer and UV doses on the ground: two years with close-to-ozone-hole conditions in the Arctic in the recent decade (, 6) The ozone story is not over yet! - Previous inter-comparison activities of existing UV/ozone measurements (Ny- Ålesund, Hornsund, Barentsburg?) were not completed satisfactorily. - Establishment of new station in Longyearbyen, starting of Brewer measurements in Ny-Ålesund Revisitation of existing data series since 99s and intercomparison campaign of all current instruments
NILU s Ozone/UV monitoring instruments GUV 54 multi-wavelength moderate bandwidth filter instrument: Five UV channels (35 nm, 33 nm, 3 nm, 34 nm and 38 nm) FWHM ~ nm in UV channels Main parameter: UV doses; additionally total O 3 column, effective albedo/cloud cover Start of measurements: 995 SAOZ UV/Vis spectrometer: Zenith sky observations of 3 6 nm spectral range ( nm resolution) with diode array detector derivation of total O 3, NO, O 4 and H O columns based on DOAS approach during periods of SZA 8 93 (sunrise, sunset measurements; no measurements during summer and winter) Start of measurements: 99 Dobson spectrometer no. 8: calibrated/reliable measurements from 994 to 3
Instrumentation at the Dirigibile Station, Ny-Ålesund UV-RAD radiometer: measures spectral radiance in 8 channels between 3 to 4 nm FWHM ca. nm operational since 8 Data coverage: since 8, but with gaps in and most of 3 Brewer spectrometer: Operational since: 3 Calibrated in 5 in cooperation with NILU
Polish Polar Station Hornsund February 996: Start of measurements of UV-B radiation at the Polish Polar Station, Hornsund, Svalbard, (77.N, 5.55E), using Robertson Berger type UV meter. Operated by Institute of Geophysics, PAS. Hornsund
New/additional Instrumentation Since April 5: UVS-AE-T UV Radiometer Sunshine duration meter CSD- CM Pyranometer (All instruments from Kipp & Zonen)
Solar UV Radiation Monitoring in Longyearbyen Operated by: University of South Bohemia in České Budějovice, Czechia Coordinates: N78.39, E5.65895 Altitude: 7 m a.s.l. Location: Roof of Julius Payer House, Czech Research Station, Longyearbyen In operation from: 4 August 7 Instrumentation and settings UVS-E-T radiometer (Kipp & Zonen, Holland) EdgeBox V Data Logger (EMS, Czechia) Sampling interval: 5 s Recording interval: 5 s Julius Payer House in Longyearbyen Installation of UVS-E-T radiometer Credits: Norwegian Polar Institute
Total ozone measurements at Ny-Ålesund Data series composed of groundbased (since 99: SAOZ, Dobson, GUV) and satellite data (979-99: TOMS-Nimbus 7, -Meteor-3) Separate trends before (and including) 997 and after 997: -7.%/decade (annual, 979-997) -.4%/decade (annual, 998-5) Large seasonal differences: -.7%/dec. (March-May, 979-997).%/dec. (March-May, 998-5) -.6%/dec. (June-August, 979-997) -.6%/dec. (June-August, 998-5) Time series of monthly mean total ozone (mixed sources) at Ny-Ålesund 979 5 (upper panel); residuals of months March-October after removal of annual cycle and trends before and after 997 (lower panel).
UV measurements and trends Ny-Ålesund Annual doses (day 6 85): continuous GUV data, except 5 Annual dose trend: -.8%/decade (non-significant) Large variability in monthly trends: Spring equinox: -8.% / decade (marked cloud transmittance reduction: more clouds?) June: -.7% / decade (cloud transmittance reduction: less snow?) July: +5.8% / decade (cloud transmittance increase: less clouds?) September: -.5% / decade (cloud transmittance reduction: less snow?)
Comparison of longest UV time series Daily erythemal dose (kj m - ) Daily erythemal dose (kj m - ) 3 3 Ny-Ålesund Hornsund 995 5 5 Years Daily erythemal dose time series at Ny-Ålesund (upper panel) and Hornsund (lower panel) as measured with the GUV filter instrument (Ny-Ålesund) and combined Robertson Berger UV meter (996 4) and UVAE-T Kipp & Zonen radiometer (4 6) at Hornsund
Spectral analysis of time series AMPLITUDE A (kj m - ) - - -3-4 3 4 - - Ny-Ålesund Hornsund Prominent features: - Annual cycle - Semi-annual cycle: albedo/snow cover? - 4-monthly cycle:? - Separation of long-term and short-term variations for further analysis at a period of 7 days -3-4 3 4 PERIOD (days)
Long- vs. short-term variations Daily erythemal dose (kj m - ) Long period component (kj m - ) Short period component (kj m - ) 3 3 - Ny-Ålesund - 995 5 5 Years Hornsund 995 5 5 Years Long-term variations very similar at the two stations, but larger amplitudes of short-term variations at Hornsund
Comparison, continued Daily erythemal dose DH (kj m-) at Hornsund Measured values Long period component Short period component 3 3 3 - - 3 - - - Daily erythemal dose DN (kj m ) at Ny-Ålesund DH =.6 +.95*DN R ² =.8 DH =.3 +.99*DN R ² =.98 Very good (mean) correlation between long-term components (but much larger deviations in individual years), obviously less spreading in Ny-Ålesund short-term variations
Comparison GUV UV-RAD Comparison of two different instruments at the same location: only started Very good dynamic agreement between the two instruments, but systematic offset (higher doses derived from GUV) Candidate for explanation: radiation transfer model systematic discrepancy in effective cloud transmittance
Summary and Outlook UV-ICARE - an effort to expand the UV network to all settlements on Svalbard and to coordinate and homogenize the different measurement techniques Re-analysis and comparison of existing UV data (ca. years) ongoing Negative trend (statistically non-significant) of annual integrated dose since the late 99s Large variability of monthly integrated doses: probably combined effect of ozone recovery, changes in cloudiness, reduced snow cover season, reduced aerosol load End of April 8: inter-comparison campaign in Ny-Ålesund including instruments from all stations with UV measurements