A surface renewal model to analyze infrared image sequences of the ocean surface for the study of air‐sea heat and gas exchange

Garbe, Christoph S.; Schimpf, U.; Jähne, Bernd

doi:10.1029/2003jc001802

Cited by 65 publications

(81 citation statements)

References 39 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Maximum likelihood analysis of the surface age obtained from the hybrid Lagrangian tracing and temperature method shows that the best fit is a lognormal distribution as plotted in Figure 2, which is indeed what has been used in some experiments [e.g., Garbe et al, 2004]. We also note that the error caused by neglecting the turbulent advection increases with time.…”

supporting

confidence: 70%

“…If the surface velocity field can be measured, the hybrid Lagrangian tracing and temperature method developed in this study has the advantage of being more accurate. This new method can also be used in experiments, since recent developments in particle image velocimetry and infrared cameras have made it possible to make high resolution measurement of surface velocity and scalar [Zappa et al, 1998;Garbe et al, 2004;McKenna and McGillis, 2004]. We hope direct comparison of Lagrangian studies between experiment and simulation can be performed in the near future.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Surface age of surface renewal in turbulent interfacial transport

Kermani¹,

Shen²

2009

Geophysical Research Letters

View full text Add to dashboard Cite

[1] We use direct numerical simulation to study characteristics of interfacial transfer of gas and heat in free-surface turbulence. Using Lagrangian tracing, we are able to directly quantify surface age of surface renewal for the first time. The physical meaning of surface renewal and various representations of surface age, including the use of heat as a proxy, are discussed. Results show that the Higbie penetration theory and the Danckwerts random surface renewal model are inappropriate for gas transfer. [2] Surface renewal is a critical process in turbulent interfacial transport that is important to many applications including sea surface temperature and atmosphere -ocean gas transfer. Scalar transport in the upper ocean is governed by the interplay of molecular diffusion at the sea surface and turbulent mixing underneath. When a surface renewal occurs, fluid is brought from the bulk towards the surface, the scalar is highly mixed, and the gradient of scalar concentration is increased at the surface to enhance interfacial diffusion.[3] An influential model of surface renewal is the penetration theory of Higbie [1935], which stated that the surface is intermittently exposed to turbulent upwelling flows. The turbulent mixing process was considered instant, with the scalar well mixed. After this surface renewal, molecular diffusion was assumed to dominate in the scalar boundary layer till the next surface renewal is generated by the turbulence below. Take gas as an example. Its concentration c is governed by the diffusion equation:2 ). Here D is the molecular diffusivity and z is the vertical coordinate. Subject to the boundary conditions at the surface c(z = 0, t) = c 0 and in the deep region c(z = À1, t) = c bulk , and the initial condition c(z, t = 0) = c bulk , the gas flux at the surface q g obtains asIn the above, the time elapsed since the surface renewal is called the surface age t.[4] Danckwerts [1951] elaborated the penetration theory in his random surface renewal model by assuming that the chance of a surface element being renewed by fresh fluid from the bulk flow is independent of its surface age. Therefore, the probability density function (pdf) of the surface age governed by dp(t)/dt = Às p(t), where p is the pdf and s is the fractional rate of surface elements being renewed (assumed to be constant by Danckwerts), has an exponential solution: p(t) = s exp(Àst). With this pdf, average surface age can be obtained as t = 1/s, and average gas flux at the surface is q g = (c 0 1951] did not account for effects of vertical turbulent advection after t = 0. Near the surface, the advection is in the form of upwelling and can be measured by surface divergency a = @u/@x + @v/@y = À@w/@z (so that w = Àaz), which was considered by Ledwell [1984] and Banerjee [1990]. The relative effects of diffusion and advection can be seen in the upwelling stagnation flow model of Chan and Scriven [1970], in which the advectiondiffusion equation @c/@t = az(@c/@z) + D(@ 2 c/@z 2 ) is solved to obtain the surface gas flux base...

show abstract

supporting

confidence: 70%

mentioning

confidence: 99%

Surface age of surface renewal in turbulent interfacial transport

Kermani¹,

Shen²

2009

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Strictly speaking, one must start by solving the heat budget equation (see [17,18]), which involves in situ measurements of heat flux boundary conditions, and then face the directional ambiguity of converting a scalar gradient into a surface velocity vector field. A more feasible quantitative method for analyzing infrared imagery involves turbulent length scale analysis, which can lead to useful quantities such as the depth of the flow and its dissipation rate [19,20].…”

Section: Infrared Methodsmentioning

confidence: 99%

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

et al. 2018

View full text Add to dashboard Cite

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.Keywords: airborne remote sensing; ocean surface currents; upper ocean turbulence BackgroundCapabilities for spatial measurements of ocean surface turbulence are highly desirable for a wide variety of needs ranging from basic studies of upper ocean mixing processes to data assimilation into high-resolution coastal and ocean circulation models. On the global scale, presently available observations of the ocean currents are provided by satellite altimeters, which are limited to mesoscales and resolve only the geostrophic component of the surface current. Much anticipated launches of the

show abstract

“…First, Melville et al (1998), then more recently Handler et al (2001Handler et al ( , 2012, Zhang and Harrison (2004), Garbe et al (2004), and Handler and Smith (2011) investigated various aspects of wind and wave driven surface turbulence in wind-wave laboratory tanks. In the field, this work was expanded further by Sutherland (2013) and Sutherland andMelville (2013, 2015a,b) with a stereo IR setup on R/P FLIP.…”

Section: Introductionmentioning

confidence: 99%

Stereo Thermal Marking Velocimetry

Savelyev

Fuchs

2018

Front. Mech. Eng.

View full text Add to dashboard Cite

This paper presents a novel approach to measuring and mapping shape and motion of the water surface. The approach combines and borrows from existing techniques, such as stereo imaging shape recognition and tracking, infrared (IR) laser marking and thermography, and particle image velocimetry. The system consists of a high power IR laser beam controlled by a programmable marking head and two IR cameras tracking the thermal pattern projected by the beam onto the water surface. The paper provides detailed description of the setup, discusses the choice of the thermal pattern, and describes the IR image processing algorithm. An example of resolved surface shape and velocity maps is given for an experiment conducted in a laboratory wave tank.

show abstract

A surface renewal model to analyze infrared image sequences of the ocean surface for the study of air‐sea heat and gas exchange

Cited by 65 publications

References 39 publications

Surface age of surface renewal in turbulent interfacial transport

Surface age of surface renewal in turbulent interfacial transport

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

Stereo Thermal Marking Velocimetry

Contact Info

Product

Resources

About