The oceans have their desert zones, in other words areas poor in nutrients and unfavourable for phytoplankton to develop. Half of the southern Pacific thus consists of great expanses of warm water with an average temperature of 28 °C (a greater surface area than Europe), which receives no input of deep-source cold water, rich in nutrient salts.
However, in 2000 analyses of satellite observations on the colour of the ocean conducted by American scientists revealed unusually high concentrations of chlorophyll -the green pigment carried by phytoplankton- in these unfertile areas. These accumulations were associated with the movement of Rossby waves and variations in ocean height they generate (2). An initial hypothesis proposed that Rossby waves induce an intermixing which prompts intermingling between the layers of warm water at the surface and the deep cold nutrient-rich water levels. This mixing wouls generate surface influx of nitrates, favourable for phytoplankton development. This hypothesis cannot explain, however, why the chlorophyll concentration peaks are always observed at the warmest spots where the water accumulates under the effect of the passing waves.
The IRD oceanographers and their co-workers investigating these effects (1) consider rather that the Rossby waves act like a rake over the ocean surface, in this way concentrating all floating particles or debris in these places where warmer water accumulates owing to greater sun exposure. This excludes the possibility of nutrients ascending from the deep cold waters by mixing. In the convergence zones produced by wave movements, there would not be any new production of phytoplankton as had been suggested, but rather an accumulation of floating organic particles of a different origin. This floating material’s optical properties are similar to those of chlorophyll, so it gives the same effect as captured by satellite observation of ocean colour, in a way misleading the calculation systems which use these satellite colour data to estimate the chlorophyll concentration.
Marie Guillaume | IRD
Seismic study reveals huge amount of water dragged into Earth's interior
18.12.2018 | National Science Foundation
A damming trend
17.12.2018 | Michigan State University
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
18.12.2018 | Materials Sciences
18.12.2018 | Physics and Astronomy
18.12.2018 | Physics and Astronomy