scholarly journals Time-series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

2016 ◽  
Vol 17 (3) ◽  
pp. 1182-1196 ◽  
Author(s):  
Brendan T. Philip ◽  
Alden R. Denny ◽  
Evan A. Solomon ◽  
Deborah S. Kelley
Keyword(s):  
Time Series ◽  
Water Column ◽  
Bubble Plume ◽  
Hydrate Ridge ◽  
Methane Distribution

scholarly journals Seasonal distributions and fluxes of <sup>210</sup>Pb and <sup>210</sup>Po in the northern South China Sea

2014 ◽  
Vol 11 (23) ◽  
pp. 6813-6826 ◽  
Author(s):  
C.-L. Wei ◽  
M.-C. Yi ◽  
S.-Y. Lin ◽  
L.-S. Wen ◽  
W.-H. Lee
Keyword(s):  
Time Series ◽  
South China Sea ◽  
Water Column ◽  
South China ◽  
Time Series Data ◽  
Northern South China Sea ◽  
Sediment Traps ◽  
Series Data ◽  
Secular Equilibrium ◽  
China Sea

Abstract. Vertical distributions of dissolved and particulate 210Pb and 210Po in the water column at the SouthEast Asian Time-series Study (SEATS, 18°00´ N and 116°00´ E) station in the northern South China Sea were determined from four cruises between January 2007 and June 2008. A large deficiency of 210Pb, 379 ± 43 × 103 dpm m−2, from the secular equilibrium was found within the 3500 m water column. On the other hand, a smaller deficiency of 210Po, 100 ± 21 × 103 dpm m−2, relative to 210Pb was found in the water column. Time-series data showed insignificant temporal variability of the 210Pb and 210Po profiles. To balance these deficiencies, the removal fluxes for 210Pb and 210Po via particle settling ranging from 45 to 51 dpm m−2d−1 and from 481 to 567 dpm m−2d−1, respectively, are expected at 3500 m. The 210Pb removal flux is comparable with, whereas the 210Po removal flux is much higher than, the flux directly measured by moored sediment traps. The discrepancy between the modeled 210Po flux and the measured flux suggests that sporadic events that enhance 210Po removal via sinking ballast may occur in the water column at the site.

scholarly journals A Time Series of Water Column Distributions and Sinking Particle Flux of Pseudo-Nitzschia and Domoic Acid in the Santa Barbara Basin, California

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 480 ◽  
Author(s):  
Blaire Umhau ◽  
Claudia Benitez-Nelson ◽  
Clarissa Anderson ◽  
Kelly McCabe ◽  
Christopher Burrell
Keyword(s):  
Time Series ◽  
Water Column ◽  
Sediment Trap ◽  
Domoic Acid ◽  
Particle Flux ◽  
Sediment Traps ◽  
Benthic Organisms ◽  
Santa Barbara ◽  
Santa Barbara Basin ◽  
Potential Source

Water column bulk Pseudo-nitzschia abundance and the dissolved and particulate domoic acid (DA) concentrations were measured in the Santa Barbara Basin (SBB), California from 2009–2013 and compared to bulk Pseudo-nitzschia cell abundance and DA concentrations and fluxes in sediment traps moored at 147 m and 509 m. Pseudo-nitzschia abundance throughout the study period was spatially and temporally heterogeneous (<200 cells L−1 to 3.8 × 106 cells L−1, avg. 2 × 105 ± 5 × 105 cells L−1) and did not correspond with upwelling conditions or the total DA (tDA) concentration, which was also spatially and temporally diverse (<1.3 ng L−1 to 2.2 × 105 ng L−1, avg. 7.8 × 103 ± 2.2 × 104 ng L−1). We hypothesize that the toxicity is likely driven in part by specific Pseudo-nitzschia species as well as bloom stage. Dissolved (dDA) and particulate (pDA) DA were significantly and positively correlated (p < 0.01) and both comprised major components of the total DA pool (pDA = 57 ± 35%, and dDA = 42 ± 35%) with substantial water column concentrations (>1000 cells L−1 and tDA = 200 ng L−1) measured as deep as 150 m. Our results highlight that dDA should not be ignored when examining bloom toxicity. Although water column abundance and pDA concentrations were poorly correlated with sediment trap Pseudo-nitzschia abundance and fluxes, DA toxicity is likely associated with senescent blooms that rapidly sink to the seafloor, adding another potential source of DA to benthic organisms.

scholarly journals Automated classification of schools of the silver cyprinid Rastrineobola argentea in Lake Victoria acoustic survey data using random forests

2020 ◽  
Vol 77 (4) ◽  
pp. 1379-1390 ◽  
Author(s):  
Roland Proud ◽  
Richard Mangeni-Sande ◽  
Robert J Kayanda ◽  
Martin J Cox ◽  
Chrisphine Nyamweya ◽  
...  
Keyword(s):  
Time Series ◽  
Water Column ◽  
Random Forests ◽  
Lake Victoria ◽  
Test Accuracy ◽  
Acoustic Survey ◽  
Automated Classification ◽  
School Based ◽  
Schooling Fish

Abstract Biomass of the schooling fish Rastrineobola argentea (dagaa) is presently estimated in Lake Victoria by acoustic survey following the simple “rule” that dagaa is the source of most echo energy returned from the top third of the water column. Dagaa have, however, been caught in the bottom two-thirds, and other species occur towards the surface: a more robust discrimination technique is required. We explored the utility of a school-based random forest (RF) classifier applied to 120 kHz data from a lake-wide survey. Dagaa schools were first identified manually using expert opinion informed by fishing. These schools contained a lake-wide biomass of 0.68 million tonnes (MT). Only 43.4% of identified dagaa schools occurred in the top third of the water column, and 37.3% of all schools in the bottom two-thirds were classified as dagaa. School metrics (e.g. length, echo energy) for 49 081 manually classified dagaa and non-dagaa schools were used to build an RF school classifier. The best RF model had a classification test accuracy of 85.4%, driven largely by school length, and yielded a biomass of 0.71 MT, only c. 4% different from the manual estimate. The RF classifier offers an efficient method to generate a consistent dagaa biomass time series.

scholarly journals Recent changes (2013-2017) in scyphomedusan fauna in the Boka Kotorska Bay, Montenegro (Southeast Adriatic)

2019 ◽  
Vol 60 (1) ◽  
pp. 25-39
Author(s):  
Ivana Violić ◽  
Davor Lučić ◽  
Ivona Milić Beran ◽  
Vesna Mačić ◽  
Branka Pestorić ◽  
...  
Keyword(s):  
Time Series ◽  
Global Warming ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Water Column ◽  
Sea Surface ◽  
Long Term Trends ◽  
Sst Anomalies ◽  
Chrysaora Hysoscella

A semi- quantitative time series (2013-2017) was used to present the recent events of scyphomedusae appearance and abundance in the Boka Kotorska Bay, Montenegro, Southeast Adriatic. Six meroplanktonic species were recorded: Aurelia spp, Chrysaora hysoscella, Cotylorhiza tuberculata ̧ Discomedusa lobata, Drymonema dalmatinum and Rhizostoma pulmo. Among them, C. hysoscella and D. lobata dominated in the water column during winter and spring, forming dense aggregations in March and May, and February to May, respectively. Our description of the D. lobata blooms are actually the first known records of blooms for this species. C. tuberculata was observed in the Bay principally in August and September. The bloom was occurred only in 2017, being the first information of C. tuberculata mass appearance in this area. We hypothesized that global warming phenomena could trigger the observed changes, and in this respect, long-term trends of sea surface temperature (SST) fluctuations were analysed. The scyphomedusae blooms coincided with high positive SST anomalies, noted in the last seven years for this area. To better understand the mechanisms underlying changes in their phenology and abundance, detailed studies on benthic stages in the Bay are essential.

scholarly journals Acoustic and optical methods to infer water transparency at the Time Series Station Spiekeroog, Wadden Sea (southern North Sea)

2016 ◽  
Author(s):  
Anne-Christin Schulz ◽  
Thomas H. Badewien ◽  
Shungudzemwoyo P. Garaba ◽  
Oliver Zielinski
Keyword(s):  
Time Series ◽  
Water Column ◽  
Wadden Sea ◽  
Acoustic Doppler Current Profiler ◽  
Water Transparency ◽  
Optical Observations ◽  
Optical Methods ◽  
Acoustic Measurements ◽  
Data Set ◽  
Acoustic Backscattering

Abstract. Water transparency is a key indicator of optical water quality that is driven by suspended particulate and dissolved material. In this study we carried out an intercomparison of observations related to water transparency, determine correlations among the measured parameters and demonstrate the utility of both acoustic and optical tools in monitoring water transparency. The data set used here is from the operational Time Series Station Spiekeroog located at a tidal inlet of the Wadden Sea. An Acoustic Doppler Current Profiler was used to obtain acoustic measurements in the water column. Optical observations were determined using a set of three radiometers above water to collect radiometric quantities and a turbidity sensor within the water column. Bio-fouling was identified as a source of anomaly in turbidity measurements. We observed significant correlations between in-situ optically measured turbidity and derived turbidity from above water color sensing and acoustic backscattering strength. These findings underline that both optical and acoustic measurements can be reasonable proxies of water transparency with the potential to mitigate gaps and increase data quality in long-time observation of marine environments.

scholarly journals Tune in on 11.57 µHz and listen to primary production

2017 ◽  
Vol 14 (22) ◽  
pp. 5271-5280
Author(s):  
Tom J. S. Cox ◽  
Justus E. E. van Beusekom ◽  
Karline Soetaert
Keyword(s):  
Time Series ◽  
Primary Production ◽  
Frequency Domain ◽  
Water Column ◽  
Gross Primary Production ◽  
Time Varying ◽  
Carrier Wave ◽  
Theoretical Derivation ◽  
Complex Demodulation ◽  
Averaging Time

Abstract. In this paper we present an elegant approach to reconstruct slowly varying gross primary production (GPP) as a function of time, based on O2 time series. The approach, called complex demodulation, is based on a direct analogy with amplitude-modulated (AM) radio signals. The O2 concentrations oscillating at the diel frequency (or 11.57 µHz) can be seen as a carrier wave, while the time variation in the amplitude of this carrier wave is related to the time-varying GPP. The relation follows from an analysis in the frequency domain of the governing equations of O2 dynamics. After the theoretical derivation, we assess the performance of the approach by applying it to three artificial O2 time series, generated with models representative of a well-mixed vertical water column, a river and an estuary. These models are forced with hourly observed incident irradiance, resulting in a variability of GPP on scales from hours to months. The dynamic build-up of algal biomass further increases the seasonality. Complex demodulation allows for reconstruction, with great precision, of time-varying GPP of the vertical water column and the river model. Surprisingly, it is possible to derive daily averaged GPP – complex demodulation thus reconstructs the amplitude of every single diel cycle. Also, in estuaries time-varying GPP can be reconstructed to a great extent. But there, the influence of the tides prevent achieving the same temporal resolution. In particular, the combination of horizontal O2 gradients with quasi-diurnal harmonics in the tides interferes with the complex demodulation procedure and introduces spurious amplitude variation that can not be attributed to GPP. We demonstrate that these spurious effects also occur in real-world time series (Hörnum Tief, Germany). The spurious effects due to K1 and P1 quasi-diurnals can not be distinguished from GPP. However, the spurious fluctuations introduced by O1 and Q1 can be removed to a large extent by increasing the averaging time to 15 days. As such, we demonstrate that a good estimate of the running 15-day average of GPP can be obtained in tidal systems. Apart from the direct merits of estimating GPP from O2 time series, the analysis in the frequency domain enhances our insights into O2 dynamics in tidal systems in general, and into the performance of O2 methods to estimate GPP in particular.

scholarly journals Contextualizing time-series data: quantification of short-term regional variability in the San Pedro Channel using high-resolution in situ glider data

2018 ◽  
Vol 15 (20) ◽  
pp. 6151-6165 ◽  
Author(s):  
Elizabeth N. Teel ◽  
Xiao Liu ◽  
Bridget N. Seegers ◽  
Matthew A. Ragan ◽  
William Z. Haskell ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Water Column ◽  
Time Series Data ◽  
Series Data ◽  
Regional Variability ◽  
Modes Of Variability ◽  
Subsurface Chlorophyll Maximum ◽  
San Pedro

Abstract. Oceanic time series have been instrumental in providing an understanding of biological, physical, and chemical dynamics in the oceans and how these processes change over time. However, the extrapolation of these results to larger oceanographic regions requires an understanding and characterization of local versus regional drivers of variability. Here we use high-frequency spatial and temporal glider data to quantify variability at the coastal San Pedro Ocean Time-series (SPOT) site in the San Pedro Channel (SPC) and provide insight into the underlying oceanographic dynamics for the site. The dataset could be described by a combination of four water column profile types that typified active upwelling, a surface bloom, warm-stratified low-nutrient conditions, and a subsurface chlorophyll maximum. On weekly timescales, the SPOT station was on average representative of 64 % of profiles taken within the SPC. In general, shifts in water column profile characteristics at SPOT were also observed across the entire channel. On average, waters across the SPC were most similar to offshore profiles, suggesting that SPOT time series data would be more impacted by regional changes in circulation than local coastal events. These results indicate that high-resolution in situ glider deployments can be used to quantify major modes of variability and provide context for interpreting time series data, allowing for broader application of these datasets and greater integration into modeling efforts.

The Effect of Varying Salinity and Temperature on the Dynamics of Orimulsion in Water

2003 ◽  
Vol 2003 (1) ◽  
pp. 419-427
Author(s):  
Merv Fingas ◽  
Zhendi Wang ◽  
Mike Landriault ◽  
Jordan Noonan ◽  
Ron MacKay
Keyword(s):  
Time Series ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Water Column ◽  
Size Distribution ◽  
Brackish Water ◽  
Water Surface ◽  
Simple Equations

ABSTRACT Studies have shown that Orimulsion behaves somewhat predictably in saltwater (33 ppt NaCl) and freshwater, driven by buoyancy to rise in saltwater and sink in freshwater, but behaviour in brackish water (20 ppt NaCl) is difficult to predict. Temperature has also been indicated as having an influence on Orimulsion behaviour. The current study extended experimentation to lower temperatures and a large number of salinity values, ranging from fresh to saltwater. This study resulted in information on the behaviour of Orimulsion spills in salt, fresh, and brackish water with salinity values ranging from 0.1 to 33 °/oo at temperatures of 5 and 15 °C. Depletion rates and characteristics were determined by adding Orimulsion to a 300-L tank of water, taking a time series of samples, and determining the concentration of bitumen and the particle size distribution. Changes in bitumen concentration and particle size distribution as a function of time were also measured. Resurfaced bitumen was scraped from the top of the tank and weighed to determine the amount rising. Using these data, simple equations were developed to describe and predict the concentration of bitumen in the water column as a function of time. Similarly, nomograms showing the amount of oil on the bottom and on the water surface are presented.

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