Coastal upwellings in the Sea of Marmara

Based on in situ measurements between 2017 and 2022 in the Sea of Marmara, three "warm and saline" upwelling events were observed during autumn and winter scientific expeditions. These observations were crucial and worth mentioning since the surface salinity value increased and even reached the lower layer value, which is ~38 psu, during the process. Other characteristics of the lower layer were also detected, either as they are or in between upper- and lower-layer values due to mixing. After analysing the effects of coastal upwellings on the upper layer, it was concluded that coastal upwelling, which has been underestimated for a long time, has to be well studied because it could be another reason or way of nutrient enrichment in the upper layer and salinity increase in winters. This phenomenon also has huge potential to differ the upper layer characteristics with a rise in frequency. Therefore, it is advised that coastal upwelling should always be considered with other well-known features during marine studies and for future engineering solutions in the basin.