Internal Waves as a Source of Concentric Rings within Small River Plumes

Alexander Osadchiev,Roman Sedakov,Alexandra Barymova,Alexandra Gordey

doi:10.3390/rs13214275

Abstract

This study is focused on concentric rings, which are regularly observed by remote sensing of small river plumes located in different regions worldwide. We report new aerial observations of these features obtained by quadcopters and supported by synchronous in situ measurements, which were collected during the recent field survey at the Bzyb river plume in the eastern part of the Black Sea. Joint analysis of remote sensing imagery and in situ data suggest that the observed concentric rings are surface manifestations of high-frequency internal waves generated in the vicinity of the river mouth. The obtained results demonstrate that the propagation of these waves does not induce offshore material transport within the plume induced by shear instability, which was hypothesized in a recent numerical modeling study of this process. We provide an explanation for the appearance of misleading material features in the numerical simulations discussed above. Finally, we discuss directions for future research of high-frequency internal waves generated in small river plumes.

Highlights

Based on the newly collected in situ data and the continuous aerial observations of these features at the Bzyb river plume [5,10], we confirm that the observed concentric rings are surface manifestations of internal waves and are not material features
This study is focused on patterns of concentric rings occurring within small river plumes in many coastal areas worldwide (Figure 11)
We analyzed new aerial observations and in situ measurements of these features in the Bzyb river plume in the eastern part of the Black Sea collected in April 2021

Summary

Introduction

2021, 13, 4275 jump and internal waves did not form within the plume; the model reproduced ring-like features somewhat similar to those observed in the Mzymta River. Based on the numerical results, they hypothesized that the concentric rings observed within real small river plumes are formed by shear instability and are not induced by high-frequency internal waves.

Results

Conclusion