Daily cycles and totals of global radiation, recorded at the automatic weather stations on the coast of Estonia, were compared with those at Tartu-Tõravere where the quality of data is guaranteed, as this station belongs to the BSRN (Baseline Surface Radiation Network). The time period for comparison was 2005–2010, but due to the extensive gaps (mostly due to low quality) in the data sets, local differences in the radiation regime were estimated on the basis of shorter time periods. On the annual basis, there is more sunshine on the West-Estonian islands and coast and less on the North-Estonian coast. On the monthly basis, an interesting feature may be noticed concerning two sites on the northern coast: in April the daily totals at Harku are larger than at Narva-Jõesuu and in July vice versa. The possibilities of reconstruction of the global radiation in coastal sites from Tõravere data are analysed. Linear regression has been checked for afternoon data for two states of cloudiness: clear and overcast. Regression gives good results everywhere when both sites are cloud-free – coefficient of correlation is practically 1.0. In overcast conditions the correlation is over 0.8 for Tiirikoja and Pärnu, over 0.7 for Harku and less for the most distant sites Vilsandi and Narva-Jõesuu. This might help marine scientists to derive estimates of solar radiation at the seaside from Tõravere data. The first analysis of new data from automatic weather stations shows that the quality of data needs attention and situation in the stations needs improvement.
1. Kawai, Y. and Wada, A. Diurnal sea surface temperature variation and its impact on the atmosphere and ocean: a review. J. Oceanogr., 2007, 63, 721–744.
2. Lips, U., Lips, I., Kikas, V. and Kuvaldina, N. Ferrybox measurements: a tool to study meso-scale processes in the Gulf of Finland (Baltic Sea). In US/EU-Baltic International Symposium, 2008 IEEE/OES: 1-8. DOI: 10.1109/BALTIC.2008.4625536
3. Lips, U., Lips, I., Liblik, T., Kikas, V., Altoja, K., Buhhalko, N. and Rünk, N. Vertical dynamics of summer phytoplankton in a stratified estuary (Gulf of Finland, Baltic Sea). Ocean Dynamics, 2011, 61, 903–915.
4. Burchard, H. and Hofmeister, R. A dynamic equation for the potential energy anomaly for analysing mixing and stratification in estuaries and coastal seas. Est. Coast. Shelf Sci., 2008, 77, 579–687.
5. Van Aken, H. M. Meteorological forcing of long-term temperature variations of the Dutch coastal waters. J. Sea Res., 2010, 63, 143–151.
6. Lips, I. and Lips, U. Abiotic factors influencing cyanobacterial bloom development in the Gulf of Finland (Baltic Sea). Hydrobiologia, 2008, 614, 133–140.
7. Eerme, K., Kallis, A., Veismann, U. and Ansko, I. Long-term variations of available solar radiation on seasonal timescales in 1955–2006 at Tartu-Tõravere Meteorological Station, Estonia. Theor. Appl. Climatology, 2010, 101, 371–379.
8. Belcher, B. N. and DeGaetano, A. T. A revised empirical model to estimate solar radiation using automated surface weather observations. Solar Energy, 2007, 81, 329–345.
9. Russak, V. and Kallis, A. (compilers). Handbook of Estonian Solar Radiation Climate. EMHI, Tallinn, 2003.
10. McArthur, B. Baseline Surface Radiation Network. Operations Manual. Version 2.1. WMO, Geneva, 2004.
11. Solar Instruments, CMP Series Pyranometers Manual, Kipp & Zonen, www.kippzonen.com, 17.03.2011.
12. Philipona, R. Underestimation of solar global and diffuse radiation measured at Earth’s surface. J. Geophys. Res., 2002, 107, D22, 4654.
13. Averkiev, M. S. An improved method for calculating total radiation. Vestnik Mosk. Univ., Ser. Geogr., 1961, No. 1, 40–47 (in Russian).14. Keevallik, S. and Loitjärv, K. Solar radiation at the surface around the Baltic Proper. Oceanologia, 2010, 52, 1–15.