[2] River plumes are regarded as water masses formed as a result of transformation of freshwater discharge in coastal sea on diurnal to synoptic time scales, while ROFI’s reproduce transformation of freshwater discharge on seasonal to annual time scales.
In particular, salinity and velocity fields in the vicinity of a freshwater source are significantly different as compared to the outer parts of a plume.
The strength and extent of this influence mainly depend on the volume of freshwater discharge and varies from negligible impact of small plumes formed by rivers with low discharge rates to the formation of stable freshened water masses in the upper ocean by the World’s largest rivers on wide coastal and shelf areas.
The latter water masses with spatial extents on the order of hundreds of kilometers are referred to as regions of freshwater influence.
These water masses are characterized by rather homogenous structure, significantly greater spatial scales, and lower temporal variability, as compared to river plumes.