Structure and variability of the Pechora plume in the southeastern part of the Barents Sea

Abstract

The Pechora River forms the large Pechora River plume in the southeastern part of the Barents Sea (also called the Pechora Sea). Many previous works addressed water masses in the Barents Sea, however, the Pechora plume received relatively little attention, therefore, many basic aspects of its structure and variability remain unknown. In this study, we focus on spreading of the Pechora plume in the Pechora Sea during ice-free periods. Based on the extensive in situ measurements and satellite observations, we describe the dependence of area and spatial characteristics of the Pechora plume on wind forcing, river discharge rate, and spring ice conditions. We reveal three general types of Pechora plume spreading, which are determined by the external forcing conditions. Joint analysis of a large set of in situ and satellite data provided opportunity to study the variability of the Pechora plume on the synoptic, seasonal, and interannual time scales. We reveal regular advection of the Pechora plume through the Kara Strait into the Kara Sea. In addition, we describe formation of a significant area of increased salinity within the Pechora plume formed during wind-induced coastal upwelling events. The results of this research are of key importance for understanding the physical, biological, and geochemical processes in the Pechora Sea and the adjacent areas of the Barents and Kara seas.

Macrozoobenthos of the Pechora Bay in 2020–2021 indicates a likely change of common bivalve molluscs in the Arctic estuary

“…In general, long-term dynamics of the Pechora River discharge are characterised by two altering phases (Georgiadi and Groisman 2022): decreased flow (1936-1955; 1967-1980) and increased flow (1956-1966;1981-present) with difference of up to 500 m 3 s −1 (8-10 km 3 year −1 ) during freshet period, corresponding to less than 10% of total annual discharge. This is noticeably lower than interannual variability with the difference in maximum and minimum discharge in spring flood period between the consecutive years sometimes reaching 30-40 km 3 according to the analysis of multi-annual discharge data (Magritsky et al 2017;Rogozhin et al 2023). Overall, no significant changes in hydrological regime of the Pechora River have been reported in literature (Magritsky et al 2018;Frolova et al 2022).…”

“…The lack of statistically significant differences between data from 1990s and 2020-2021 can be explained by a potentially high stability of estuarine macrozoobenthos, but also by the high spatial heterogeneity and interannual variability of macrozoobenthos in the area-to gain a better understanding of the temporal dynamics of macrozoobenthos in the context of ongoing climate change in the region, long-term timeseries data are essential. No significant changes were found in freshwater input during last decades (Magritsky et al 2017;Rogozhin et al 2023) to explain the lack of P. aestuariorum in the area, thus the nature of the disappearance of the previously common bivalve mollusc (Mosevich 1928) remains uncertain and requires further investigation.…”

“…Interannual variability of external factors in the Pechora Sea region (river runoff, wind conditions and others) has a noticeable impact on the salinity values across the Pechora Bay (Rogozhin et al 2023), which is why the salinity of both surface and bottom water in the research area in 2020 was lower than in 2021. In addition, in 2021 the water column was stratified across the plume area, and the frontal zone dividing Pechora Bay water from the more saline Barents Sea water was located 30-40 km closer to the river mouth than in 2020.…”

“…Figure 3 illustrates vertical salinity structure in the Pechora Bay in 2020 (a) (19-20 July) and 2021 (b) (19-20 July). In 2020, salinity values varied from 3 PSU for the subsurface waters at the river mouth (station D11), which is strongly affected by the riverine influence, to 24-26 PSU for the near-bottom waters of the seaward station D2, where saline Barents Sea waters are having a strong influence on the near-bottom water mass (Byshev et al 2003;Rogozhin et al 2023). The Pechora Bay waters were fully mixed from surface to bottom, evident from the vertical salinity profiles (Fig.…”

Surface microplastics in the Kara Sea: from the Kara Gate to the 83°N

“…The hydrological conditions in the Kara Gate are influenced by the dynamics of the Pechora river plume and wind-driven currents. Recent studies revealed regular advection of the Pechora plume through the Kara Gate into the Kara Sea (Rogozhin et al, 2023). Pechora plume can act as a barrier from the south for microplastics coming from the Barents Sea and direct particles towards the Kara Gate or prevent the influx of MPs coming from Barents Sea.…”