Tales of the Wild

Computing the ocean's true colors

 Modeled phytoplankton types on cubed sphere

The data is from a simulation of the Darwin model in a physical run of the MITgcm by the ECCO2 group.

The model has 78 types of phytoplankton, nutrients, zooplankton and disolved and particulate organic matter. 

(other video)

From Phys.org by Mark Dwortzan

When she was 17, Stephanie Dutkiewicz set sail from her native South Africa to the Caribbean islands.
Throughout a three-month journey, she noticed that the color of the ocean shifted from place to place, but it wasn't until she took up oceanography in college that she came to understand why.
Early on in her studies, she learned that ocean color varies from green to blue, depending on the type and concentration of phytoplankton (algae) in the area.
As they use chlorophyll, a green pigment, to generate organic carbon through photosynthesis, these "plants of the sea" reflect light; the more phytoplankton in the ocean, the less blue and more green the color of the water.

Stephanie Dutkiewicz in her office with a display of her phytoplankton model simulation.

Credit: MIT Joint Program on the Science and Policy of Global Change

Now a principal research scientist in MIT's Joint Program on the Science and Policy of Global Change and Department of Earth, Atmospheric and Planetary Sciences (EAPS), Dutkiewicz remains focused on these drivers of ocean color.

For more than a decade, she and her main research partner, EAPS Associate Professor Mick Follows, have been leading a team of a dozen MIT researchers and several collaborators from universities around the world to advance the Darwin Project, which aims to model the growth, loss, and movement of phytoplankton around the world, the environments that they inhabit, and how they affect one another.
Dutkiewicz is systematically probing phytoplankton behavior to home in on what traits distinguish one of thousands of phytoplankton species from another, which types will survive and thrive under different environmental conditions, and where different types are likely to live.

Guided by laboratory, ship, and satellite observations, she has represented as many as 100 different types of phytoplankton—other groups typically model no more than five—in complex computer models that simulate phytoplankton population dynamics in the ocean and project how those dynamics will change in coming decades.
Producing results that square with actual observations, these models, which comprise hundreds of thousands of lines of code, are generating the world's most complex 2-D and 3-D global maps of phytoplankton activity and ocean color.

Visually arresting, the maps suggest profound implications for the future of the planet, from the sustainability of the ocean's food web to the pace of global warming.
"Since they are at the base of the food web, understanding which types of phytoplankton live where and projecting how these populations are likely to change will help us understand what will happen further up the food chain," Dutkiewicz explains.

"And because the process by which these phytoplankton take carbon and sink it down into the deep ocean is responsible for storing about 200 parts per million (ppm) of carbon dioxide, they play an important role in the Earth's climate system."

Size matters

In an ongoing phytoplankton modeling study funded by the National Science Foundation, Dutkiewicz and Follows are investigating several distinguishing traits and their potential impact on the planet.

Traits they've identified include those based on behavior, such as rates of nutrient uptake, temperature tolerance and light tolerance, and those based on size.
In the phytoplankton world, size matters.

While all are microscopic, individual phytoplankton range in diameter from under 1 micrometer to more than 1,000 micrometers—akin to the size difference between a mouse and Manhattan.

As the ocean warms, its upper layers are expected to interact less with lower layers where nutrients are concentrated.

As a result, smaller phytoplankton, which are best equipped to tolerate compromised nutrient conditions, will likely outnumber larger phytoplankton, which are more effective at storing carbon. Such changes may not only shift the oceanic food web to one based on smaller phytoplankton but also reduce the ocean's effectiveness as a carbon sink.

Computer simulations based on Dutkiewicz’ phytoplankton models have produced global maps of ocean color like this “Living Liquid” exhibit at the San Francisco Exploratorium — an interactive touchscreen table showing phytoplankton types in different colors. Credit: San Francisco Exploratorium

Most phytoplankton models, including those used by the Intergovernmental Panel on Climate Change (IPCC), usually resolve just two phytoplankton types: small and large.

So when the ocean warms to a certain point in the coming decades, the modelled phytoplankton populations appear to shift dramatically, with small ones far outnumbering large ones. In reality, however, these shifts are expected to occur gradually.
"Because we include a more diverse size distribution in our model, we find that as we run out the 21st century, phytoplankton sizes don't quickly shift from big to small, but rather from big to slightly smaller," says Dutkiewicz.

"So the impact might not be as large as the IPCC models predict."
To assess the impact of phytoplankton size and function on the climate, Dutkiewicz and her collaborators represent the global ocean as a set of location-based grid cells, each sized at a resolution that's fine enough to validate the model through satellite and ship observations.

Within each grid cell, the model solves a set of equations that account for phytoplankton growth, movement, loss, carbon cycling and other population dynamics.

Comparison of modeled and SeaWiFs Chl

True colors

With funding from NASA, Dutkiewicz is also using the computer model to "ground-truth" satellite observations of phytoplankton concentrations in different parts of the ocean, which are based on how much light is emitted from the ocean surface.

The light is reflected by chlorophyll in phytoplankton, which absorb more blue than green light.

By measuring how much blue versus green light is emitted, the satellites estimate how much chlorophyll is present at a given location.

Such estimates are crude at best, so Dutkiewicz is working to assess the level of uncertainty in chlorophyll ocean maps by representing reflected light in her phytoplankton models.
Her models produce true colors of the ocean today, and project ocean colors throughout the 21st century based on changes in phytoplankton population dynamics.

For example, as the ocean warms and becomes more acidic, phytoplankton populations will change, thus altering chlorophyll levels and impacting how much light is reflected from the ocean surface.

"Tracking this could help us identify a real, climate-change-driven signal that stands out from the year-to-year, natural variability in phytoplankton populations across the globe," she says.

Dutkiewicz' career path as an oceanographer has uniquely positioned her to pinpoint such signals.

As a PhD student in physical oceanography at the University of Rhode Island, she originally focused on capturing the movement of ocean currents.

When she came to MIT in 1998 as a postdoc in EAPS, she studied how physics alters the biology of phytoplankton (e.g. how ocean currents move their biological cargo), and built a numerical model of the marine ecosystem based on one type of phytoplankton.

Now modeling up to 100 times as many types, she is perhaps the most qualified person in the world to explain not only why the colors of the ocean vary from place to place, but also what those colors might portend for the future of the planet.

Links :

• Phys.org : Study reveals 'two faces' of phytoplankton 
• NASA : Ocean color 
• GeoGarage blog :NASA's PACE mission will uncover new information about health of our oceans / Image of the week : winter blooms in the Arabian Sea / Earth pictures from space / Image of the week : Plankton bloom, Black Sea / Image of the week : plankton arrives in Scandinavia / Scientists point out reason behind North Atlantic phytoplankton bloom

Greenland's huge annual ice loss is even worse than thought

Aerial surveys show two glaciers flowing into Johan Petersen fjord in south-eastern Greenland.

The melting of the ice sheet would cause oceans to rise by six metres around the world if it was lost entirely.

Photograph: Jeremy Harbeck/Icebridge/NASA

From The Guardian by Damian Carrington

Ice cap is disappearing far more rapidly than previously estimated, and is part of a long-term trend, new research shows

The huge annual losses of ice from the Greenland cap are even worse than thought, according to new research which also shows that the melt is not a short-term blip but a long-term trend.
The melting Greenland ice sheet is already a major contributor to rising sea level and if it was eventually lost entirely, the oceans would rise by six metres around the world, flooding many of the world’s largest cities.
The new study reveals a more accurate estimate of the ice loss by taking better account of the gradual rise of the entire Greenland landmass.
When the ice cap was at its peak 20,000 years ago, its great weight depressed the hot, viscous rocks in the underlying mantle.
As ice has been shed since, the island has slowly rebounded upwards.
Previous satellite estimates of modern ice losses tried to take this into account, but precise new GPS data showed much of Greenland is rising far more rapidly than thought, up to 12mm a year.
This means 19 cubic kilometres more ice is falling into the sea each year, an increase of about 8% on earlier figures.

The southern tip of Greenland seen from space.

Photograph: ISS/NASA 

The faster rebound is thought to be the result of hotter, more elastic mantle rocks under eastern Greenland, a remnant from 40m years ago when the island passed over the hot spot that now powers Iceland’s volcanoes.
The new work was also able to reconstruct the ice loss from Greenland over millennia and found that the same parts of Greenland - the north-west and south-east - were where most ice is being lost both in the past and today.
This means the rapid ice loss recorded by satellite measurements over the last 20 years is not likely to be a blip, but part of a long-term trend being exacerbated by climate change.
Global warming is driving major melting on the surface of Greenland’s glaciers and is speeding up their travel into the sea.
“The fact that we are seeing such a similarity of past and present behaviour suggests we could lose ice in these regions for decades into the future,” said Prof Jonathan Bamber, at the University of Bristol, UK, and one of the international team of scientists who carried out the new study, published in Science Advances.

 Aerial Camera views from shore visits on the east and west coasts of Greenland, August 2016.

(Rob Dunbar)

Bamber said the presence of a long-term trend does not mean global warming is not a crucial factor: “One thing we can be certain of is that a warmer atmosphere and a warmer ocean is only going to accelerate this trend.”
“The headlines of climate change and melting polar ice are not going to change,” said Dr Christopher Harig, at the University of Arizona, who was not involved in the study.
“The new research happening now really speaks to the question: ‘How fast or how much ice can or will melt by the end of the century?’ As we understand more the complexity of the ice sheets, these estimates have tended to go up. In my mind, the time for urgency about climate change [action] really arrived years ago, and it’s past time our policy reflected that urgency.”

Melt water on the surface of Greenland ice sheet 10 June, 2014 and 15 June, 2016.

Every spring or early summer, the surface of the sheet transforms from a vast white landscape of snow and ice to one dotted with blue meltwater streams, rivers, and lakes.

In 2016, the transition started early and fast.

Credits: OLI/Landsat 8 and ALI/Earth Observing-1/Nasa

Dr Pippa Whitehouse, at the University of Durham and also not involved in the new research, said: “This study highlights the powerful insight that GPS measurements can give into past and present ice loss. Using such measurements, this study demonstrates that some of the highest rates of ice loss across Greenland - both in the past and at present - are found in areas where the ice sheet flows directly into the ocean, making it dangerously susceptible to future warming in both the atmosphere and the ocean.”

 This video shows images from a science flight on August 27, 2016, over a heavily crevassed portion of the Rink Glacier in western Greenland.

NASA's Operation IceBridge flies with a high-resolution camera on board, pointing straight down and taking overlapping images during the entire flight. These images represent a data product in their own right, and also provide a visual reference to help researchers better understand the data they get from other instruments.

(NASA/Rob Russell)

The team behind the new research said better estimates of continental rebound rates could be even more significant in estimates of ice loss from the world’s biggest ice cap, in Antarctica, but that sparse data from the remote continent made analysis difficult.
In April, very high temperatures led to a record-breaking early onset of glacier melting in Greenland, while another satellite study in August reaffirmed the rapid loss of ice.

Links :

• YouTube : Greenland's Glaciers on the Loose: Fiamma Straneo
• NASA : Southern Greenland
• Washington Post : Greenland may be losing ice even faster than scientists thought 
• University Buffalo : What’s happening beneath Greenland?
• GeoGarage blog : Global warming is melting the Greenland ice sheet, fast / Greenland's ice layers mapped in 3D / New NASA model maps sea level rise like never before /Greenland: Like the most beautiful woman / Greenland glacier calves island four times the size of Manhattan

Faroe islands in the GeoGarage platform

DGA raster maps in the GeoGarage platform 

 ENC Faroë coverage in the GeoGarage platform (ArcGIS JS viewer) :
more raster charts than ENCs available

FÆROARUM – Prima & accurata delineatio.

Hanc veterrimam tabulam insularum Lucas Debes anno 1673 fecit.

 

Nautical map of the Faroz Islands (dépôt de la Marine,1820)

Fisrt accurate triangulation of the Faroes
 

The Faroe islands (Føroyar) became a self governing community of the Danish Commonweath
on April 1, 1948 and are administrated from Tórshavn.
(raster chart with the GeoGarage and Google Maps viewer)

comparaison with ENC chart in the GeoGarage platform and Bing maps imagery

La Niña might not be coming after all

Sea surface temperature patterns of the 2015 El Niño

don’t show any signs of an impending La Niña this year.

Image: NASA

From Gizmodo by Maddie Stone

After promising biblical rains and instead giving California crabs, El Niño passed away quietly last spring. But while early data suggested La Niña would rise to fill the chasm El Niño’s departure had left in our meteorological newsfeeds, NOAA is now starting to think La Niña might not happen at all.

 As early as last winter, climate forecasters told us they were “reasonably confident” La Niña conditions would emerge by late 2016.
As the spring wore on, our confidence in the anti-El Niño climate pattern grew stronger, bolstered by the expansion of a telltale, cold water undercurrent in the equatorial Pacific.
When that cold water mass started to breach the surface last May, ending the reign of El Niño’s hot blob once and for all, climatologists forecasted a 75 percent chance La Niña would be here by the end of the year.

Monthly sea surface temperature anomalies in the Niño 3.4 region of the tropical Pacific, with El Nino and La Nina threashold conditions indicated by dashed lines.

Image: Climate.gov

But late last week, NOAA’s Climate Prediction Center poured some cold water on our hope that lots and lots of cold water would spread across the Pacific’s midsection, perhaps even making a temporary dent in our global, carbon emissions-fueled heat wave.
Last week, the La Niña watch was officially taken down. Forecasters are now placing their bets on ENSO-neutral conditions (aka, neither El Niño nor La Niña) persisting through the winter.

What changed?
As a blog post by NOAA explains, we’re still measuring cooler-than-average temperatures across the so-called Niño 3.4 region of the tropical Pacific, which are considered typical for La Niña. But that temperature dip hasn’t been accompanied by the La Niña atmospheric response.
By this point, we should be seeing an amping up of the Walker circulation pattern, meaning cool air should be sinking more vigorously in the central and eastern Pacific as warm air rises more vigorously over the western Pacific.

 El Niño and La Niña, the warm and cool phases of the El Niño-Southern Oscillation, disrupt large-scale air movements in the tropics, impacting weather patterns across the world.

Image: Climate.gov

An intensification of Walker circulation would strengthen westerly winds across the tropical Pacific, leading to more rainfall over places like Indonesia.
“So far, there have only been some very weak indications of this intensification,” NOAA writes. And without these atmospheric acrobatics, the cool subsurface waters in the Niño 3.4 region are likely to fizzle out.
La Niña could still happen—it might just be a late bloomer.
But the probability that we’ll be welcoming a La Niña into the world this winter has been downgraded significantly to about 40 percent.

As disappointing as this is, it’s worth remembering that El Niño, too, was a bit of a let-down.
Despite having virtually tied the 1997-98 El Niño in terms of strength, our planetary party guest didn’t end California’s drought, although that may have been an unreasonable expectation. It sorta figures that El Niño’s alter ego would be a no-show.

Links :

• NASA : After strong El Niño, NASA sees return to normal
• Climate.gov : September 2016 ENSO update: Cooling our heels
• ClimateCentral : Is La Niña Here? Depends Who You Ask