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    Atmosfääri seire
    Seasonal correlation between Southern Estonian temperature and Arctic temperature at 1000 hPa vertical level; E. Jakobson.

    Workgroup of remote sensing of the atmosphere has two research areas: 1) ultraviolet (UV) radiation and related climate factors; 2) climate change.

    In past years main focus of UV related research has been on the analysis of spectral composition and how it is dependent on climate factors. Spectral measurements of UV radiation (280-400 nm) began in Tartu Observatory in 2004. The work group is also managing a sun photometer belonging to NASA AERONET and measuring aerosol characteristics. There is also a collaboration with the Tartu-Tõravere meteorological station near the observatory. Also a method and models for UV calculations has been developed using ARESLab (based on MARS) and libRadtran software. With the models reconstruction of UV doses from 1955 to 2003 has been done and the models are in use to fill gaps in the measurements. Newest research is focusing on vitamin D synthesizing radiation. At present knowledge vitamin D synthesis is the most important beneficial influence of UV radiation. Considering that the prognosis made by the WMO shows lower UV levels in the future for our latitude and thus increasing risk of vitamin D deficit, it is important to know the available radiation levels for that process.

    Team of climate change is focused on reasons of climate changes in the Baltic Sea region and in the Arctic. Our goals are to find ultimate causes between temperature, atmospheric energy balance components, aerosols and greenhouse gases temporal variability, we also study teleconnections between Baltic Sea region and Arctic climate. We use global atmospheric reanalyse models NCEP-CFSR and ERA-Interim, aerosol model SILAM and atmosphere radiation transfer model FUTBOLIN. We validate model using measured data (radiosondes, radiometers, AERONET sun photometer). The most substantial goal is to estimate different climate parameters (water vapour, CO2, aerosols) changes contribution in the climate change. IPCC report (2007) refers that that in US standard atmosphere conditions, water vapour is responsible of 60% and CO2 of 26% of the greenhouse effect. How big are the proportions in Estonia in winter and in the Arctic with sometimes even 10 times less water vapour? We have qualitatively shown that the difference is not very large and is visible mostly at lower altitudes. The work is ongoing to get quantitative results.