scholarly journals Soundscapes in the German Baltic Sea Before and During the Covid-19 Pandemic

2021 ◽  
Vol 8 ◽  
Author(s):  
Fritjof Basan ◽  
Jens-Georg Fischer ◽  
Dennis Kühnel
Keyword(s):  
Baltic Sea ◽  
Marine Environment ◽  
Sound Pressure ◽  
Anthropogenic Sources ◽  
Data Sets ◽  
Sea State ◽  
Low Frequencies ◽  
Spatial And Temporal Scales ◽  
Acoustic Data ◽  
Noise Input

Anthropogenic underwater noise has been identified as one of the main pressures on the marine environment. Considerable research efforts have been made to quantify acoustic soundscapes on different spatial and temporal scales in order to identify trends and investigate how this may impact the marine environment. Measures to reduce noise input into the seas from anthropogenic sources are under discussion, including the reduction of vessel speed or re-routing of shipping lanes. The decline in maritime transport as a consequence of the Covid-19 pandemic provides an opportunity to examine the associated extent of noise reduction. Here, we present the results of a “Before-After-Control-Impact” study where we analyzed acoustic data sets from two monitoring stations in the German Baltic Sea. Data were collected between 2013 and 2020. As part of an international initiative, coordinated by the International Quiet Ocean Experiment, monthly statistics (20 average sound pressure levels per 1/3 octave bands) were calculated from acoustic data collected during the pre-pandemic period (2013–2019), and were compared with data from the year 2020, during the Covid-19 pandemic. To account for varying natural conditions the measurements were sorted into categories of same prevailing sea state. Through this approach, measurements with equivalent natural noise impact are compared and any resulting differences are likely due to the variability in the anthropogenic noise. A decline in sound pressure of 13% (1.2 dB) for low frequencies (10 Hz–1 kHz) was observed at both stations, which corresponds to the reduced level of shipping activity.

scholarly journals Upwelling-induced trace gas dynamics in the Baltic Sea inferred from 8 years of autonomous measurements on a ship of opportunity

2021 ◽  
Vol 18 (8) ◽  
pp. 2679-2709
Author(s):  
Erik Jacobs ◽  
Henry C. Bittig ◽  
Ulf Gräwe ◽  
Carolyn A. Graves ◽  
Michael Glockzin ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Gas Dynamics ◽  
Coastal Upwelling ◽  
Regional Distribution ◽  
Trace Gas ◽  
Data Sets ◽  
The Baltic Sea ◽  
Spatial And Temporal Scales ◽  
In Situ Data ◽  
The Baltic

Abstract. Autonomous measurements aboard ships of opportunity (SOOP) provide in situ data sets with high spatial and temporal coverage. In this study, we use 8 years of carbon dioxide (CO2) and methane (CH4) observations from SOOP Finnmaid to study the influence of upwelling on trace gas dynamics in the Baltic Sea. Between spring and autumn, coastal upwelling transports water masses enriched with CO2 and CH4 to the surface of the Baltic Sea. We study the seasonality, regional distribution, relaxation, and interannual variability in this process. We use reanalysed wind and modelled sea surface temperature (SST) data in a newly established statistical upwelling detection method to identify major upwelling areas and time periods. Large upwelling-induced SST decrease and trace gas concentration increase are most frequently detected around August after a long period of thermal stratification, i.e. limited exchange between surface and underlying waters. We found that these upwelling events with large SST excursions shape local trace gas dynamics and often lead to near-linear relationships between increasing trace gas levels and decreasing temperature. Upwelling relaxation is mainly driven by mixing, modulated by air–sea gas exchange, and possibly primary production. Subsequent warming through air–sea heat exchange has the potential to enhance trace gas saturation. In 2015, quasi-continuous upwelling over several months led to weak summer stratification, which directly impacted the observed trace gas and SST dynamics in several upwelling-prone areas. Trend analysis is still prevented by the observed high variability, uncertainties from data coverage, and long water residence times of 10–30 years. We introduce an extrapolation method based on trace gas–SST relationships that allows us to estimate upwelling-induced trace gas fluxes in upwelling-affected regions. In general, the surface water reverses from CO2 sink to source, and CH4 outgassing is intensified as a consequence of upwelling. We conclude that SOOP data, especially when combined with other data sets, enable flux quantification and process studies addressing the process of upwelling on large spatial and temporal scales.

scholarly journals Upwelling-induced trace gas dynamics in the Baltic Sea inferred from 8 years of autonomous measurements on a ship of opportunity

2020 ◽  
Author(s):  
Erik Jacobs ◽  
Henry C. Bittig ◽  
Ulf Gräwe ◽  
Carolyn A. Graves ◽  
Michael Glockzin ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Gas Dynamics ◽  
Coastal Upwelling ◽  
Regional Distribution ◽  
Trace Gas ◽  
Data Sets ◽  
The Baltic Sea ◽  
Spatial And Temporal Scales ◽  
In Situ Data ◽  
The Baltic

Abstract. Autonomous measurements aboard ships of opportunity (SOOP) provide in situ data sets with high spatial and temporal coverage. In this study, we use 8 years of carbon dioxide (CO2) and methane (CH4) observations from SOOP Finnmaid to study the influence of upwelling on trace gas dynamics in the Baltic Sea. Between spring and autumn, coastal upwelling transports water masses enriched with CO2 and CH4 to the surface of the Baltic Sea. We study the seasonality, regional distribution, relaxation, and interannual variability of this process. We use reanalysed wind and modelled sea surface temperature (SST) data in a newly established statistical upwelling detection method to identify major upwelling areas and time periods. Strong upwelling events are most frequently detected around August after a long period of thermal stratification, i.e. limited exchange between surface and underlying waters. We found that these strong upwelling events with large SST excursions shape local trace gas dynamics and often lead to near-linear relationships between increasing trace gas levels and decreasing temperature. Upwelling relaxation is mainly driven by mixing and modulated by air–sea gas exchange and possibly primary production. Subsequent warming through air–sea heat exchange has the potential to enhance trace gas saturation. In 2015, quasi-continuous upwelling over several months led to weak summer stratification, which directly impacted the observed trace gas and SST dynamics in several upwelling-prone areas. We introduce an extrapolation method based on trace gas – SST relationships that allows us to estimate upwelling-induced trace gas fluxes in upwelling-affected regions. In general, the surface water reverses from CO2 sink to source and CH4 outgassing is intensified as a consequence of upwelling. We conclude that upwelling is an important and relevant process controlling trace gas dynamics in near-coastal environments in the Baltic Sea, and that SOOP data, especially when combined with other data sets, enable flux quantification and process studies on larger spatial and temporal scales.

scholarly journals Rapid speciation in a newly opened postglacial marine environment, the Baltic Sea

2009 ◽  
Vol 9 (1) ◽  
pp. 70 ◽  
Author(s):  
Ricardo T Pereyra ◽  
Lena Bergström ◽  
Lena Kautsky ◽  
Kerstin Johannesson
Keyword(s):  
Baltic Sea ◽  
Marine Environment ◽  
The Baltic Sea ◽  
Rapid Speciation ◽  
The Baltic

Low Wave Number Radar Image Energy Influence on Determining Current

2012 ◽  
Vol 433-440 ◽  
pp. 6054-6059
Author(s):  
Gan Nan Yuan ◽  
Rui Cai Jia ◽  
Yun Tao Dai ◽  
Ying Li
Keyword(s):  
Wave Spectrum ◽  
Surface Current ◽  
Sea Surface ◽  
Radar Image ◽  
Wave Number ◽  
Sea State ◽  
Low Frequencies ◽  
In Situ Data ◽  
Main Effects

In the radar imaging mechanism different phenomena are present, as a result the radar image is not a direct representation of the sea state. In analyzing radar image spectra, it can be realized that all of these phenomena produce distortions in the wave spectrum. The main effects are more energy for very low frequencies. This work investigates the structure of the sea clutter spectrum, and analysis the low wave number energy influence on determining sea surface current. Then the radar measure current is validated by experiments. By comparing with the in situ data, we know that the radar results reversed by image spectrum without low wave number spectrum have high precision. The low wave number energy influent determining current seriously.

scholarly journals Comparison of three airborne laser bathymetry data sets for monitoring the German Baltic Sea Coast

2015 ◽  
Author(s):  
Yujin Song ◽  
Joachim Niemeyer ◽  
Wilfried Ellmer ◽  
Uwe Soergel ◽  
Christian Heipke
Keyword(s):  
Baltic Sea ◽  
Data Sets ◽  
Airborne Laser ◽  
Sea Coast

scholarly journals Irradiance Variability Quantification and Small-Scale Averaging in Space and Time: A Short Review

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 264 ◽  
Author(s):  
Gerald Lohmann
Keyword(s):  
Short Review ◽  
Power Grids ◽  
Small Scale ◽  
Stable Operation ◽  
Data Sets ◽  
Spatial Smoothing ◽  
Spatial And Temporal Scales ◽  
Output Variability ◽  
Temporal Averaging

The ongoing world-wide increase of installed photovoltaic (PV) power attracts notice to weather-induced PV power output variability. Understanding the underlying spatiotemporal volatility of solar radiation is essential to the successful outlining and stable operation of future power grids. This paper concisely reviews recent advances in the characterization of irradiance variability, with an emphasis on small spatial and temporal scales (respectively less than about 10 km and 1 min), for which comprehensive data sets have recently become available. Special attention is given to studies dealing with the quantification of variability using such unique data, the analysis and modeling of spatial smoothing, and the evaluation of temporal averaging.

scholarly journals Hydrological and hydrochemical underpinnings of primary production and division of the Russian sector in the Gdansk basin of the Baltic sea

2019 ◽  
Vol 59 (1) ◽  
pp. 56-71
Author(s):  
E. A. Kudryavtseva ◽  
S. V. Aleksandrov
Keyword(s):  
Primary Production ◽  
Baltic Sea ◽  
Marine Environment ◽  
Bottom Topography ◽  
Water Area ◽  
Nutrient Concentrations ◽  
The Baltic Sea ◽  
Environment Temperature ◽  
Russian Sector ◽  
The Baltic

The distribution patterns of absolute and specific values of primary production in the upper 10-m layer depending on the physical and chemical condition of the marine environment (temperature, salinity, depth, bottom topography and configuration of the coastline, and nutrient concentrations) were distinguished in the Russian sector in the Gdansk Basin of the Baltic Sea based on long-term research data (2003–2015). Based on the results, the considered water area was divided into five regions: Cape Taran, the base of the Curonian Spit, the plateau of Rybachy, the open sea, and the Gdansk Bay (northeastern part). These regions are characterized by higher correlations of primary production and parameters of the marine environment compared to regression analysis for the regions distinguished by bathymetry. Primary production is the most closely correlated with temperature over the entire water area and with nutrients concentrations in seaward regions.

scholarly journals Prediction of noise from wind turbines: theoretical and experimental study

2018 ◽  
pp. 34-41 ◽  
Author(s):  
Carlos Alberto Echeverri-Londoño ◽  
Alice Elizabeth González Fernández
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Sound Pressure ◽  
Prediction Method ◽  
Wide Band ◽  
Propagation Models ◽  
Low Frequencies ◽  
High Frequencies ◽  
Wind Speeds ◽  
Sound Pressure Levels

Several noise propagation models used to calculate the noise produced by wind turbines have been reported. However, these models do not accurately predict sound pressure levels. Most of them have been developed to estimate the noise produced by industries, in which wind speeds are less than 5 m/s, and conditions favor its spread. To date, very few models can be applied to evaluate the propagation of sound from wind turbines and most of these yield inaccurate results. This study presents a comparison between noise levels that were estimated using the prediction method established in ISO 9613 Part 2 and measured levels of noise from wind turbines that are part of a wind farm currently in operation. Differences of up to 56.5 dBZ, with a median of 29.6 dBZ, were found between the estimated sound pressure levels and measured levels. The residual sound pressure levels given by standard ISO 9613 Part 2 for the wind turbines is larger for high frequencies than those for low frequencies. When the wide band equivalent continuous sound pressure level is expressed in dBA, the residual varies between −4.4 dBA and 37.7 dBA, with a median of 20.5 dBA.

scholarly journals Development of marine landscape maps for the Baltic Sea and the Kattegat using geophysical and hydrographical parameters

2007 ◽  
Vol 13 ◽  
pp. 61-64 ◽  
Author(s):  
Zyad K. Al-Hamdani ◽  
Johnny Reker ◽  
Jørgen O. Leth ◽  
Anu Reijonen ◽  
Aarno T. Kotilainen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Marine Environment ◽  
Leisure Activities ◽  
Biological Information ◽  
Marine Biodiversity ◽  
The European Union ◽  
The Baltic Sea ◽  
Marine Habitats ◽  
The Baltic ◽  
Bothnian Bay

The Baltic Sea is one of the largest brackish water bodies in the world (Segerstråle 1957) with a number of basins varying from almost fresh water in the northern part of the Bothnian Bay via the more brackish conditions in the southern part to the saline waters of the Kattegat. The Baltic Sea is subject to severe environmental degradation caused by commercial and leisure activities, including fisheries, dredging, tourism, coas t a l development and land-based pollution sources. This causes severe pressures on vulnerable marine habitats and natural re- sources, and a tool for aiding marine management is therefore strongly needed. The marine landscape concept presented by Roff &Taylor (2000) is based on the use of available broad-scale geological, physical and hydrographical data to prepare ecologically meaningful maps for areas with little or no biological information. The concept, which was elaborated by Day & Roff (2000) was applied in UK waters (Connor et al. 2006) before it was adopted by the BALANCE project described here. The aim of developing marine landscape maps is to characterise the marine environment of the Baltic Sea region (the Baltic Sea together with the Kattegat) using geophysical and hydrographical parameters. Such maps can be applied, for example, to an assessment of the Baltic-wide network of marine protected areas, and thus provide a sustainable ecosystem-based approach to the protection of the marine environment from human activities, and contribute to the conservation of marine biodiversity. The BALANCE project is based on transnational and cross-sectoral co-operation with participants from nine countries surrounding the Baltic Sea as well as Norway (Fig. 1), and is partially financed by the European Union through the BSR INTERREG IIIB programme.

Directional sound processing and interaural sound transmission in a small and a large grasshopper

1995 ◽  
Vol 198 (9) ◽  
pp. 1817-1827 ◽  
Author(s):  
A Michelsen ◽  
K Rohrseitz
Keyword(s):  
Outer Surface ◽  
Sound Pressure ◽  
Schistocerca Gregaria ◽  
Sound Transmission ◽  
Directional Hearing ◽  
Sound Processing ◽  
Low Frequencies ◽  
High Frequencies ◽  
Physical Mechanisms ◽  
Chorthippus Biguttulus

Physical mechanisms involved in directional hearing are investigated in two species of short-horned grasshoppers that differ in body length by a factor of 3­4. The directional cues (the effects of the direction of sound incidence on the amplitude and phase angle of the sounds at the ears) are more pronounced in the larger animal, but the scaling is not simple. At high frequencies (10­20 kHz), the sound pressures at the ears of the larger species (Schistocerca gregaria) differ sufficiently to provide a useful directionality. In contrast, at low frequencies (3­5 kHz), the ears must be acoustically coupled and work as pressure difference receivers. At 3­5 kHz, the interaural sound transmission is approximately 0.5 (that is, when a tympanum is driven by a sound pressure of unit amplitude at its outer surface, the tympanum of the opposite ear receives a sound pressure with an amplitude of 0.5 through the interaural pathway). The interaural transmission decreases with frequency, and above 10 kHz it is only 0.1­0.2. It still has a significant effect on the directionality, however, because the directional cues are large. In the smaller species (Chorthippus biguttulus), the interaural sound transmission is also around 0.5 at 5 kHz, but the directionality is poor. The reason for this is not the modest directional cues, but rather the fact that the transmitted sound is not sufficiently delayed for the ear to exploit the directional cues. Above 7 kHz, the transmission increases to approximately 0.8 and the transmission delay increases; this allows the ear to become more directional, despite the still modest directional cues.

Sign in / Sign up

Export Citation Format

Share Document