Simplistic underwater ambient noise modelling for shallow coastal areas: Lithuanian area of the Baltic Sea

It is known that underwater sea soundscapes are produced by natural noise sources that occur on the water surface and subsurface water layers. Wind, water splashes, sprays, and breaking waves produce a bubble layer, which in turn produces downward directed sound radiation. There are several additional sources that contribute to underwater noise levels, mainly from commercial shipping, and various anthropogenic sources both out at sea and in coastal areas. Recent research projects have investigated the effects of shipping traffic on the ambient soundscape in the Baltic Sea, stressing the need for long term ambient soundscape monitoring using underwater noise measurements and modelling. Freely available underwater noise models allow for the evaluation of ambient noise levels produced on water surfaces as well, as the creation of soundscape maps. In this manuscript, a simplistic underwater noise model is presented, developed for evaluating and mapping the soundscape in shallow marine areas, and for investigating the noise levels in different seasons.