Coupled Model Simulation of Wind Stress Effect on Far Wakes of Ships in SAR Images

Fujimura, Atsushi; Soloviev, Alexander; Rhee, Shin Hyung; Romeiser, Roland

doi:10.1109/tgrs.2015.2502940

Cited by 21 publications

(15 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the bubbles created in the turbulent wake can affect the gas exchange between ocean and atmosphere, in addition to the increased gas exchange due to the turbulence itself (Trevorrow et al, 1994;Weber et al, 2005;Emerson and Bushinsky, 2016). The episodic nature, intensity, and duration of the ship-induced turbulence is also of a magnitude that has been shown to affect the mortality of copepods and diatoms (Bickel et al, 2011;Garrison and Tang, 2014). Moreover, in areas with intense ship traffic, the ship-induced vertical mixing could possibly affect nutrient availability and natural biogeochemical cycles in seasonally stratified waters if the mixing is deep and intense enough to entrain water from below the thermocline.…”

mentioning

confidence: 99%

In situ observations of turbulent ship wakes and their spatiotemporal extent

et al. 2021

View full text Add to dashboard Cite

Abstract. In areas of intensive ship traffic, ships pass every 10 min. Considering the amount of ship traffic and the predicted increase in global maritime trade, there is a need to consider all types of impacts shipping has on the marine environment. While the awareness about, and efforts to reduce, chemical pollution from ships is increasing, less is known about physical disturbances, and ship-induced turbulence has so far been completely neglected. To address the potential importance of ship-induced turbulence on, e.g., gas exchange, dispersion of pollutants, and biogeochemical processes, a characterisation of the temporal and spatial scales of the turbulent wake is needed. Currently, field measurements of turbulent wakes of real-size ships are lacking. This study addresses that gap by using two different methodological approaches: in situ and ex situ observations. For the in situ observations, a bottom-mounted acoustic Doppler current profiler (ADCP) was placed at 32 m depth below the shipping lane outside Gothenburg harbour. Both the acoustic backscatter from the air bubbles in the wake and the dissipation rate of turbulent kinetic energy were used to quantify the turbulent wake depth, intensity, and temporal longevity for 38 ship passages of differently sized ships. The results from the ADCP measurements show median wake depths of 13 m and several occasions of wakes reaching depths > 18 m, which is in the same depth range as the seasonal thermocline in the Baltic Sea. The temporal longevity of the observable part of the wakes had a median of around 10 min and several passages of > 20 min. In the ex situ approach, sea surface temperature was used as a proxy for the water mass affected by the turbulent wake (thermal wake), as lowered temperature in the ship wake indicates vertical mixing in a thermally stratified water column. Satellite images of the thermal infrared sensor (TIRS) onboard Landsat-8 were used to measure thermal wake width and length, in the highly frequented and thus major shipping lane north of Bornholm, Baltic Sea. Automatic information system (AIS) records from both the investigated areas were used to identify the ships inducing the wakes. The satellite analysis showed a median thermal wake length of 13.7 km (n=144), and the longest wake extended over 60 km, which would correspond to a temporal longevity of 1 h 42 min (for a ship speed of 20 kn). The median thermal wake width was 157.5 m. The measurements of the spatial and temporal scales are in line with previous studies, but the maximum turbulent wake depth (30.5 m) is deeper than previously reported. The results from this study, combined with the knowledge of regional high traffic densities, show that ship-induced turbulence occurs at temporal and spatial scales large enough to imply that this process should be considered when estimating environmental impacts from shipping in areas with intense ship traffic.

show abstract

mentioning

confidence: 99%

In situ observations of turbulent ship wakes and their spatiotemporal extent

et al. 2021

View full text Add to dashboard Cite

show abstract

“…It should be noted that the wake‐to‐background contrast in magnitude is depending on SAR frequency band, resolutions, incidence angles, polarisations, sea states, ship speed, hull shape, and ship propulsion system etc. [4–7]. The visibilities of ship wakes may be reduced under some conditions, i.e.…”

Section: Methodsmentioning

confidence: 99%

“…The turbulence wake consists of a large number of short waves in disarray on the sea surface. For SAR images of the ship wakes, reports and analyses have been presented based on the measured radar dataset [5, 6] and hydrokinetics simulations [7]. A representative description for the distant wakes of a moving ship in SAR images is usually as a linear feature [5, 6].…”

Section: Introductionmentioning

confidence: 99%

Ship wake region detection by using multi‐feature recombination and area‐based morphological analysis in ATI‐SAR systems

Mao

Yang

Mao

et al. 2019

J. eng.

View full text Add to dashboard Cite

“…Remote sensing approaches focused on detecting wakes from a surveillance perspective (Fujimura et al, 2016) or the theoretical possibility of doing so (Issa and Daya, 2014). These approaches mainly rely on Synthetic Aperture Radar (SAR) to identify sea surface roughness.…”

Section: Introductionmentioning

confidence: 99%

<i>In situ</i> observations of turbulent ship wakes and their potential implications for vertical mixing

Nylund

Arneborg

Tengberg

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. In areas of intensive ship traffic, ships pass every ten minutes. Considering the amount of ship traffic and the fact that global maritime trade is predicted to increase, there is a need to consider all effects shipping has on the marine environment; both pollution and physical disturbances. This paper studies a previously disregarded physical disturbance, namely ship-induced vertical mixing in the turbulent wake. A characterization of the temporal and spatial scales of the turbulent wake is needed to estimate its effect on gas exchange, dispersion of pollutants, and to identify in which areas ship-induced vertical mixing could have an impact on local biogeochemical cycles. There is a lack of field measurements of turbulent wakes of real-size ships, and this study addresses that gap by in situ and ex situ measurements of the depth, width, length, intensity and longevity of the turbulent wake for ~240 ship passages of differently sized ships. A bottom-mounted Acoustic Doppler Current Profiler (ADCP) was placed at 32 m depth below the ship lane outside Gothenburg harbour, and used to measure wake depth and temporal longevity. Thermal satellite images of the Thermal Infrared Sensor (TIRS) onboard Landsat 8 were used to measure thermal wake width and spatial longevity, using satellite scenes from the major ship lane North of Bornholm, Baltic Sea. Automatic Information System (AIS) records from both the investigated areas were used to identify the ships inducing the wakes. The results from the ADCP measurements show median wake depths of ~ 10 m, and several occasions of wakes reaching depths > 18 m. The temporal longevity of the wakes had a median of around 8 min and several passages of > 20 min. The satellite analysis showed a median thermal wake length of 13.7 km, and the longest wake extended over 60 km, which would correspond to a temporal longevity of 1 h 42 min (for a ship speed of 20 knots). The median thermal wake width was 157.5 m. The measurements of the spatial and temporal scales are in line with previous studies, but the deep mixing and extensive longevity presented in this study, has not previously been documented. The results from this study have shown that ship-induced vertical mixing occurs at temporal and spatial scales large enough to imply that this process should be considered when estimating environmental impact from shipping in areas with intense ship traffic. Moreover, the possibility that deep vertical mixing could occur in a highly frequent manner highlights the need of further studies to better characterize the spatial and temporal development of the turbulent wake.

show abstract

Coupled Model Simulation of Wind Stress Effect on Far Wakes of Ships in SAR Images

Cited by 21 publications

References 21 publications

In situ observations of turbulent ship wakes and their spatiotemporal extent

In situ observations of turbulent ship wakes and their spatiotemporal extent

Ship wake region detection by using multi‐feature recombination and area‐based morphological analysis in ATI‐SAR systems

<i>In situ</i> observations of turbulent ship wakes and their potential implications for vertical mixing

Contact Info

Product

Resources

About

Coupled Model Simulation of Wind Stress Effect on Far Wakes of Ships in SAR Images

Cited by 21 publications

References 21 publications

In situ observations of turbulent ship wakes and their spatiotemporal extent

In situ observations of turbulent ship wakes and their spatiotemporal extent

Ship wake region detection by using multi‐feature recombination and area‐based morphological analysis in ATI‐SAR systems

&lt;i&gt;In situ&lt;/i&gt; observations of turbulent ship wakes and their potential implications for vertical mixing

Contact Info

Product

Resources

About

<i>In situ</i> observations of turbulent ship wakes and their potential implications for vertical mixing