Larsen, S.E, & Svendsen, L.M. 2021. Statistical aspects in relation to Baltic Sea Pollution Load Compilation. Task under HELCOM PLC-8 project. Aarhus University, DCE – Danish Centre for Environment and Energy, 60 pp. Technical Report No. 224 http://dce2.au.dk/pub/TR224.pdf
The HELCOM project for the Eight Baltic Sea Pollution Load Compilation (PLC-8) includes the tasks of preparing a comprehensive assessment of the water- and airborne inputs of nutrients and their sources to the Baltic Sea during the monitoring period of 1995-2022. The project includes a follow up on the implementation of the HELCOM nutrient reduction scheme and assessment of the effectiveness of measures to reach the BSAP targets.
The tasks in the PLC-8 project call for standardized and appropriate methodologies, especially statistical methods. Statistical methods, in the PLC-8 project, are used for testing and estimating the trends in nutrient input time series including test for change points, and to give an estimate of the uncertainty in nutrient inputs datasets. Statistical methods are used to evaluate the progress of fulfilling the HELCOM BSAP nutrient reduction targets (Maximum Allowable Inputs (MAI)) and national Nutrient Input Ceilings (NIC) taking into account the uncertainty and variation of the nutrient inputs over time.
This is the fourth version of the collection of statistical aspects and methods first compiled as a part of the former HELCOM PLC-6 project. The report presents the statistical methods in a theoretical mathematical setup supplied with numerous examples of their use on nutrient inputs to the Baltic Sea. The methods included: testing for data outliers and filling in data gaps, hydrological normalization of time series of nutrient inputs, estimating uncertainty of nutrient inputs, trend analysis and modelling of the normalized inputs over time, testing for change points, and finally testing for fulfillment of the reduction targets (MAI and NIC).
