Observations show that after stormy events, anthropogenic litter is washed ashore for short periods of time, providing the opportunity to collect and remove it from the environment. However, water dynamics in sea coastal zones during and after storms are very complicated, and the transport properties of litter items are very diverse; thus, predicting litter wash-outs using classical numerical models is challenging. We analyze meteorological and hydrophysical conditions in the Baltic Sea coastal zone to further use the obtained data as a training sequence for an artificial neural network (ANN). Analysis of the physical processes behind large litter wash-outs links open-source meteorological (wind speed and direction) and hydrodynamic reanalysis (surface wave parameters) data to the time and location of these wash-outs. A detailed analysis of 25 cases of wash-outs observed at the shore of the Sambian Peninsula was performed. The importance of the duration of the storm and its subsiding phase was revealed. An ANN structure is proposed for forecasting marine debris wash-outs as the first step in the creation of a neural network-based tool for managers and beach cleaners, helping to plan effective measures to remove plastics and other anthropogenic contaminants from the marine environment.

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<p>The problem of contamination of the shore of the Sambian Peninsula with marine anthropogenic litter is pressing and requires detailed study since it has a detrimental effect on the touristic and recreational activity of the region. Observations show that the most volumetric marine litter wash-outs to the beach take place after certain storms and are associated with abundant spots ofbiota (primarily branched Furcellaria lumbricalis). Such spots contain litter of anthropogenic origin, such as glass, paper, etc., along with macro and micro plastics. In this paper, meteorological and hydrophysical data were collected and analyzed in order to determine the most significant factors causing the wash-outs of anthropogenic marine litter to the shore of Sambian Peninsula. Both in-situ observations and reanalysis datasets were used for the analysis. It was revealed that the wash-out to the shore occurs during the storm subsiding phase, and the determining factors are significant wave height, wind speed and current velocity during the preceding storm.</p><p>Investigations are supported by the Russian Science Foundation, grant No 19-17-00041 and IKBFU competitiveness improvement program for 2016-2020 (project 5-100).</p>

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