Influence of natural surfactants on short wind waves in the coastal Peruvian waters

Kiefhaber, Daniel; Zappa, Christopher J.; Jähne, Bernd

doi:10.5194/osd-12-1291-2015

Cited by 3 publications

(8 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Near the coast, the agreement between wind-and helium-derived mean vertical velocities is fair, if a "minimum" water depth of 50 m for upwelling to occur is chosen. For the Peruvian upwelling, the vertical velocity-derived from the helium method in conjunction with the gas exchange parameterization of Nightingale et al (2000) leads to an overestimation of the upwelling, as the gas exchange is reduced due to the presence of surface surfactants (Kiefhaber et al, 2015). Assuming a reduction of the piston velocity in the whole coastal area off Peru leads to a small underestimation of the upwelling, but helium-and wind-derived values still agree within their errors.…”

Section: Discussionmentioning

confidence: 86%

“…(3) due to the presence of organic surface films (surfactants). These films have been observed on cruise M91, and their damping behaviour on surface waves have been shown in Kiefhaber et al (2015). There, the observed mean square slope of the waves was found to be overestimated by the parameterization for clean water.…”

mentioning

confidence: 74%

“…3a for the standard gas exchange shows that the overall pattern of the distribution of the vertical velocities remains unchanged, only the coastal values are smaller. In Kiefhaber et al (2015) not all data points are influenced by surfactants. As illustrated in Fig.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

et al. 2015

View full text Add to dashboard Cite

Abstract.Upwelling is an important process, bringing gases and nutrients into the ocean mixed layer. The upwelling velocities, however, are too small to be measured directly. Here we use the surface disequilibrium of the 3 He / 4 He ratio measured in two coastal upwelling regions off Peru in the Pacific ocean and off Mauritania in the Atlantic ocean to calculate the regional distribution of vertical velocities. To also account for the fluxes by diapycnal mixing, microstructurebased observations of the vertical diffusivity have been performed on all four cruises analysed in this study. The upwelling velocities in the coastal regions vary between 1.1 ± 0.3 × 10 −5 and 2.8 ± 1.5 × 10 −5 m s −1 for all cruises. Vertical velocities are also inferred from the divergence of the wind-driven Ekman transport. In the coastal regimes, both methods agree within the error range. Further offshore, the helium-derived vertical velocity still reaches 1 × 10 −5 m s −1 , whereas the wind-driven upwelling from Ekman suction is smaller by up to 1 order of magnitude. One reason for this difference is ascribed to eddy-induced upwelling. Both advective and diffusive nutrient fluxes into the mixed layer are calculated based on the helium-derived vertical velocities and the vertical diffusivities. The advective part of these fluxes makes up at about 50 % of the total. The nutrient flux into the mixed layer in the coastal upwelling regimes is equivalent to a net community production (NCP) of 1.3 ± 0.3 g C m 2 d −1 off Peru and 1.6-2.1 ± 0.5 g C m 2 d −1 off Mauritania.

show abstract

Section: Discussionmentioning

confidence: 86%

mentioning

confidence: 74%

See 1 more Smart Citation

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

et al. 2015

View full text Add to dashboard Cite

show abstract

“…It is, however, much too small to be measured directly. In previous studies upwelling has been derived from the wind field via Ekman theory (McClain, 1993;Hagen, 2001), the divergence of the horizontal velocity fields inferred from current metres, drifters, and shipboard measurements (Weingartner and Weisberg, 1991;Gouriou and Riverdin, 1992) and geochemical tracers such as 14 C (Broecker et al, 1978;Quay et al, 1983;Toggweiler et al, 1991), pCO 2 and AOU (Wanninkhof et al, 1995), (Tanhua and Liu, 2015) as well as the isotopes 7 Be (Kadko and Johns, 2011;Haskell II et al, 2015) and 3 He (Klein and Rhein, 2004;Rhein et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…The helium method (Klein and Rhein, 2004;Rhein et al, 2010) exploits the excess of the helium isotope 3 He in the upwelled waters to determine the vertical velocity. The oceanic source for 3 He is hydrothermal venting, mainly near R. Steinfeldt et al: Coastal upwelling mid-ocean ridges, where primordial 3 He is emitted (Lupton, 1983).…”

Section: Introductionmentioning

confidence: 99%

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

Steinfeldt¹,

Sültenfuß²,

Dengler³

et al. 2015

Preprint

View full text Add to dashboard Cite

Abstract. Oceanic upwelling velocities are too small to be measured directly. The surface disequilibrium of the 3He/4He ratio provides an indirect method to infer vertical velocities at the base of the mixed layer. Samples of helium isotopes were taken from two coastal upwelling regions, off Peru on cruise M91, and off Mauritania on 3 cruises. The helium-3 flux into the mixed layer also depends on the diapycnal mixing. Direct observations of the vertical diffusivity have been performed on all 4 cruises and are also used in this study. The resulting upwelling velocities in the coastal regions vary between 1.1 × 10−5 and 2.8 × 10−5 m s−1 for all cruises. Vertical velocities off the equator can also be inferred from the divergence of the wind driven Ekman transport. In the coastal regimes, the agreement between wind and helium derived upwelling is fairly good at least for the mean values. Further offshore, the helium derived upwelling still reaches 1 × 10−5 m s−1, whereas the wind driven upwelling from Ekman suction is smaller by at least one order of magnitude. One reason for this difference might be eddy induced upwelling. Both advective and diffusive nutrient fluxes into the mixed layer are calculated based on the helium derived vertical velocities and the measured vertical diffusivities. The advective part of these fluxes makes up at least 50 % of the total. The nutrient flux into the mixed layer in the coastal upwelling regimes is equivalent to a net community production (NCP) of 1.3 g C m2 d−1 off Peru and 1.6–1.9 g C m2 d−1 off Mauritania.

show abstract

Airborne Measurements of Surface Wind and Slope Statistics over the Ocean

Lenain

Statom

Melville

2019

Journal of Physical Oceanography

View full text Add to dashboard Cite

As reported in 1954, more than a half century ago, C. Cox and W. Munk developed an empirical model of the slope distribution of ocean surface waves that has been widely used ever since to model the optical properties of the sea surface and is of particular importance to the satellite remote sensing community. In that work, the reflectance of sunlight was photographed from a Boeing B-17G bomber and was then analyzed. In this paper, surface slope statistics are investigated from airborne scanning topographic lidar data collected during a series of field experiments off the coast of California and in the Gulf of Mexico, over a broad range of environmental conditions, with wind speeds ranging from approximately 2 to 13 m s−1. Unlike the reflectance-based approach of Cox and Munk, the slope distribution is computed by counting laser glints produced by specular reflections as the lidar is scanned over the surface of the ocean. We find good agreement with their measurements for the mean-square slope and with more recent (2006) results from Bréon and Henriot that were based on satellite remote sensing. Significant discrepancies for the higher-order statistics are found and discussed. We also demonstrate here that airborne scanning lidar technology offers a viable means of remotely estimating surface wind speed and momentum flux.

show abstract

Influence of natural surfactants on short wind waves in the coastal Peruvian waters

Cited by 3 publications

References 33 publications

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

Coastal upwelling off Peru and Mauritania inferred from helium isotope disequilibrium

Airborne Measurements of Surface Wind and Slope Statistics over the Ocean

Contact Info

Product

Resources

About