The growing need for a consistent and densified GNSS position and velocity solution for the Nordic and Baltic countries resulted in development of the joint GNSS Analysis Centre of the Nordic Geodetic Commission (NKG) in 2012. We first developed the methods of the operational processing and combination of solutions and then reprocessed the full data history between 1997 and 2017. In this study, we present an ITRF2014 densification for the area including 252 stations having more than 3 years of data. We combined all 20 years of daily solutions with full covariance matrices instead of station-wise analysis and analyzed the noise characteristics of the residual time series. We concluded that the flicker plus white noise uncertainty estimates were more robust than the general power-law estimates. Additionally, we found significant horizontal velocity differences at the co-located stations, pointing out biases not included in the formal uncertainties. The solution is more accurate and denser than any previous estimate, and it will be of great benefit for maintaining the reference frames in the Nordic and Baltic countries, as well as for the geodynamic studies in the area.

The Nordic Geodetic Commission (NKG) has launched a joint NKG GNSS Analysis Centre that aims to routinely produce high qualityGNSS solutions for the common needs of the NKG and the Nordic and Baltic countries. A consistent and densified velocity field is needed for the constraining of the gla-cial isostatic adjustment (GIA) modelling that is a key component of maintaining the national reference frame realisations in the area. We described the methods of the NKG GNSS Analysis Centre including the defined processing setup for the local analysis centres (LAC) and for the combination centres.We analysed the results of the first 2.5 years (2014.5-2016). The results showed that different subnets were consistent with the combined solution within 1-2 mm level. We observed the so called network effect affecting our reference frame alignment. However, the accuracy of the reference frame alignment was on a few millimetre level in the area of the main interest (Nordic and Baltic Countries). TheNKGGNSS AC was declared fully operational in April 2017.

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LitPOS (Lithuanian Positioning System), the network of permanent reference GNSS stations, became operational in July 2007. It provides data both for real-time and post-processing applications. Coordinate time series were obtained from LitPOS reprocessing data for years 2008–2014. The reprocessing was done using Bernese 5.2 software. The analysis of time series was done with Matlab routine “GITSA” (GPS Interactive Time Series Analysis). In this paper the review of obtained coordinate time series will be given, in addition error tracking and some of the results will be assessed. An analysis of discontinuities and outliers with possible problem solutions will be provided. As a result more consistent accumulated multi-year solution is presented.

Abstract. LitPOS (Lithuanian Positioning System), the network of permanent reference GNSS stations, became operational in July 2007. It provides data both for real-time and post-processing applications. LitPOS stations cover the whole territory of Lithuania. Total number of LitPOS GNSS stations during 2007-2014 period was 25 (since 2015 -30 stations). Also LitPOS network includes 3 ASG-EUPOS (Poland) and 6 LATPOS (Latvia) stations. LitPOS network data re-processing was done using Bernese (BSW5.2 update 2016 01 08) software. Software was slightly improved by editing scripts and writing procedures for RINEX files preparation, for downloading other necessary data, and for getting two processing solutions from single BPE (Bernese Process Engine) process (total network and sub-network without Polish and Latvian stations).