Wind on lakes brings predator and prey together in the pelagic zone

2015 ◽  
Vol 72 (11) ◽  
pp. 1652-1662 ◽  
Author(s):  
Derrick Tupper de Kerckhove ◽  
Edyta Agnes Blukacz-Richards ◽  
Brian John Shuter ◽  
Liset Cruz-Font ◽  
Peter Arnold Abrams
Keyword(s):  
Aquatic Ecosystems ◽  
Large Range ◽  
Spatial Scales ◽  
Acoustic Doppler Current Profiler ◽  
Weather Conditions ◽  
Trophic Levels ◽  
Stratified Lakes ◽  
Water Currents ◽  
Current Profiler ◽  
Calm Weather

Wind blowing over the pelagic zones of stratified lakes creates recirculating water currents. In Lake Opeongo, we observed the effects of these currents on four different trophic levels using a variety of methods (acoustic Doppler current profiler, optical plankton counter, hydroacoustics, telemetry, and netting programs). During windy events, (1) water currents were stronger than the known swimming speeds of small zooplankton (355 to 399 μm) but not larger species or fish, (2) large zooplankton (>542 μm) and schooling planktivores congregated at the thermocline at the downwind end of the basin, and (3) large piscivores directed their foraging towards areas exposed to wind, where they appeared to acquire the same meal as under calm weather conditions but with less effort. We propose that (i) the horizontal physical homogeneity of pelagic zones, (ii) the slow swimming ability of zooplankton relative to the speed of wind-induced water currents, and (iii) the likely growth benefits to predators of foraging on patches of prey lead to the downwind aggregation of pelagic organisms. We discuss this conceptual framework with examples from both lake and ocean ecosystems to suggest that this phenonenon occurs across a large range of spatial scales in aquatic ecosystems.

Recent Progress in Applying Advanced Computation Methods to Radar-Based Wave Measurements

2021 ◽  
Author(s):  
Morten Loell Vinther ◽  
Torbjørn Eide ◽  
Aurelia Paraschiv ◽  
Dickon Bonvik-Stone
Keyword(s):  
Doppler Radar ◽  
Risk Mitigation ◽  
Weather Conditions ◽  
Data Access ◽  
Environmental Data ◽  
Data Sets ◽  
Wave Measurements ◽  
Current Profiler ◽  
Pulse Doppler ◽  
Calm Weather

Abstract High quality environmental data are critical for any offshore activity relying on data insights to form appropriate planning and risk mitigation routines under challenging weather conditions. Such data are the most significant driver of future footprint reduction in offshore industries, in terms of costs savings, as well as operational safety and efficiency, enabled through ease of data access for all relevant stakeholders. This paper describes recent advancements in methods used by a dual-footprint Pulse-Doppler radar to provide accurate and reliable ocean wave height measurements. Achieved improvements during low wind weather conditions are presented and compared to data collected from other sources such as buoys and acoustic doppler wave and current profiler (ADCP) or legacy. The study is based on comparisons of recently developed algorithms applied to different data sets recorded at various sites, mostly covering calm weather conditions.

scholarly journals On the Reliability of Surface Current Measurements by X-band Marine Radar

2019 ◽  
Vol 11 (9) ◽  
pp. 1030 ◽  
Author(s):  
Hessner ◽  
El Naggar ◽  
von Appen ◽  
Strass
Keyword(s):  
Real Time ◽  
Surface Current ◽  
Acoustic Doppler Current Profiler ◽  
Weather Conditions ◽  
Operational Reliability ◽  
Current Data ◽  
X Band ◽  
Current Profiler ◽  
Marine Radar ◽  
Commercial Off The Shelf

Real-time quality-controlled surface current data derived from X-Band marine radar (MR) measurements were evaluated to estimate their operational reliability. The presented data were acquired by the standard commercial off-the-shelf MR-based sigma s6 WaMoS® II (WaMoS® II) deployed onboard the German Research vessel Polarstern. The measurement reliability is specified by an IQ value obtained by the WaMoS® II real-time quality control (rtQC). Data which pass the rtQC without objection are assumed to be reliable. For these data sets accuracy and correlation with corresponding vessel-mounted acoustic Doppler current profiler (ADCP) measurements are determined. To reduce potential misinterpretation due to short-term oceanic variability/turbulences, the evaluation of the WaMoS® II accuracy was carried out based on sliding means over 20 min of the reliable data only. The associated standard deviation σWaMoS = 0.02 m/s of the mean WaMoS® II measurements reflect a high precision of the measurement and the successful rtQC during different wave, current and weather conditions. The direct comparison of 7272 WaMoS® II/ADCP northward and eastward velocity data pairs yield a correlation of r ≥0.94, with bias∆ ≤0.06 m/s and σS=0.05 m/s. This confirms that the MR-based surface current measurements are accurate and reliable.

scholarly journals Airborne Remote Sensing of the Upper Ocean Turbulence during CASPER-East

2018 ◽  
Vol 10 (8) ◽  
pp. 1224
Author(s):  
Ivan Savelyev ◽  
William Miller ◽  
Mark Sletten ◽  
Geoffrey Smith ◽  
Dana Savidge ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Spatial Scales ◽  
Infrared Camera ◽  
Acoustic Doppler Current Profiler ◽  
Ocean Surface ◽  
Upper Ocean ◽  
Airborne Remote Sensing ◽  
Ocean Turbulence ◽  
Ocean Surface Currents ◽  
Current Profiler

This study takes on the challenge of resolving upper ocean surface currents with a suite of airborne remote sensing methodologies, simultaneously imaging the ocean surface in visible, infrared, and microwave bands. A series of flights were conducted over an air-sea interaction supersite established 63 km offshore by a large multi-platform CASPER-East experiment. The supersite was equipped with a range of in situ instruments resolving air-sea interface and underwater properties, of which a bottom-mounted acoustic Doppler current profiler was used extensively in this paper for the purposes of airborne current retrieval validation and interpretation. A series of water-tracing dye releases took place in coordination with aircraft overpasses, enabling dye plume velocimetry over 100 m to 10 km spatial scales. Similar scales were resolved by a Multichannel Synthetic Aperture Radar, which resolved a swath of instantaneous surface velocities (wave and current) with 10 m resolution and 5 cm/s accuracy. Details of the skin temperature variability imprinted by the upper ocean turbulence were revealed in 1–14,000 m range of spatial scales by a mid-wave infrared camera. Combined, these methodologies provide a unique insight into the complex spatial structure of the upper ocean turbulence on a previously under-resolved range of spatial scales from meters to kilometers. However, much attention in this paper is dedicated to quantifying and understanding uncertainties and ambiguities associated with these remote sensing methodologies, especially regarding the smallest resolvable turbulent scales and reference depths of retrieved currents.

Klamath River Water Quality and Acoustic Doppler Current Profiler Data from Link River Dam to Keno Dam, 2007

2008 ◽  
Author(s):  
Annett B. Sullivan ◽  
Michael L. Deas ◽  
Jessica Asbill ◽  
Julie D. Kirshtein ◽  
Kenna D. Butler ◽  
...  
Keyword(s):  
Water Quality ◽  
River Water ◽  
Acoustic Doppler Current Profiler ◽  
River Water Quality ◽  
Klamath River ◽  
Current Profiler ◽  
Profiler Data
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