An international research team including Prof. Andreas Macke, Director of the Leibniz-Institute for Tropospheric Research, explained this optical phenomenon now.
Plankton bloom (Bay of Biscay on the Atlantic Ocean). Satellite: Envisat-MERIS.
Credit: European Space Agency (ESA) http://earth.eo.esa.int/cgi-bin/satimgsql.pl?show_url=4&startframe=0
Plankton bloom (near Ireland). Satellite: Envisat-MERIS. Credit: European Space Agency (ESA) http://www.esa.int/esaEO/SEM09F5OJCG_index_1.html
In a paper of the renomated science journal “Proceedings of the National Acadamy of Sciences” (PNAS) the researcher report that the typically elongated shaped bacteria get aligned in regions of largest shear of the fluid which in turn provides a stronger scattering into the forward and backward direction compared to randomly oriented particles. This orientation effect generally holds for plankton in the most upper ocean layer and would lead to a larger penetration depth of sunlight than predicted by previous models.
Wind stress at the ocean surface produces a vertical shear in which the elongated phyto plancton particles and bacteria become oriented. In case of natural microbial assemblages moderate shear velocities can increase the back (and forward) scattering of the incident light by 20%. During phyto-plankton blooms already small velocities can change scattering by more than 30%. A larger penetration depth of solar radiation would have consequences on photosynthesis rates, primary production and thus the CO2-uptake of the ocean. The study reveals a subtle interplay between fluid dynamics, ocean biology and ocean optics. “These results proof that biophysical interactions on the microscale can play an essential role on global scale marine processes,” Andreas Macke explained.
The orientation-induced change of the light transmissivity also leads to a change in the reflected sun light. The latter effects the satellite based remote sensing of plankton concentrations in the world oceans so that correction of the previously retrieved plankton loads might become necessary. Macke has demonstrated similar orientation effects for ice crystals in troposheric cirrus clouds.Publication:
Tilo Arnhold | Leibniz-Institut
Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute
Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine