SIRGAS reference frame realization SIR11P01

To estimate the kinematics of the SIRGAS reference frame, the Deutsches Geodätisches Forschungsinstitut (DGFI) as the IGS Regional Network Associate Analysis Centre for SIRGAS (IGS RNNAC SIR), yearly computes a cumulative (multi-year) solution containing all available weekly solutions delivered by the SIRGAS analysis centres. These cumulative solutions include those models, standards, and strategies widely applied at the time in which they were computed and cover different time spans depending on the availability of the weekly solutions. This data set corresponds to the multi-year solution SIR11P01. It is based on the combination of the weekly normal equations covering the time span from 2000-01-02 (GPS week 1043) to 2011-04-16 (GPS week 1631), when the IGS08 reference frame was introduced. It refers to ITRF2008, epoch 2005.0 and contains 230 stations with 269 occupations. Its precision was estimated to be ±1.0 mm (horizontal) and ±2.4 mm (vertical) for the station positions, and ±0.7 mm/a (horizontal) and ±1.1 mm/a (vertical) for the constant velocities. Computation strategy and results are in detail described in Sánchez and Seitz (2011). The IGS RNAAC SIR computation of the SIRGAS reference frame is possible thanks to the active participation of many Latin American and Caribbean colleagues, who not only make the measurements of the stations available, but also operate SIRGAS analysis centres processing the observational data on a routine basis (more details in http://www.sirgas.org). The achievements of SIRGAS are a consequence of a successful international geodetic cooperation not only following and meeting concrete objectives, but also becoming a permanent and self-sustaining geodetic community to guarantee quality, reliability, and long-term stability of the SIRGAS reference frame. The SIRGAS activities are strongly supported by the International Association of Geodesy (IAG) and the Pan-American Institute for Geography and History (PAIGH). The IGS RNAAC SIR highly appreciates all this support.

137Cs concentrations in the southeastern Baltic Sea in 1997-2000

Variations of 137Cs concentration in the southeastern Baltic Sea were investigated over the period 1997-2000, i.e. in 11-14 years after the Chernobyl Nuclear Power Plant accident. Rate of "self-cleaning" proved to be very slow. Some results obtained in 1999 were almost the same as those measured after the accident, in 1986. Calculated results showed that "Chernobyl" caesium-137 would be "cleaned" in the Baltic Sea by 2020-2022. In 2000 average concentration had to be about 50-60 Bq/m**3. Sometimes mentioned concentrations were observed. In some cases higher concentrations averaging from 67 to 80 Bq/m**3 were registered in the southeastern Baltic Sea in 1999; and in some samples 137Cs concentrations were very high. They varied from 110 to 212 Bq/m**3. No steady correlation was observed between 137Cs concentration, salinity and temperature in surface water of the area. Distribution of radionuclide concentration sometimes depends on direction of water mass transport. Abnormally high concentrations of 137Cs in the southeastern Baltic Sea may result from additional radioactive waste discharge.