Saturday, June 24, 2017

What would the ocean say?

What Would The Ocean Say? from Nancy Rosenthal
This film was produced for the United Nations in celebration of World Ocean Day
by James Cameron and the Avatar Alliance Foundation.

Friday, June 23, 2017

Decoding Antarctica's response to a warming world

The seabed drill rig (MeBo) was developed at the MARUM in order to be able to obtain cores of up to 50 m in length from loose sediments and solid rock.
The 10-ton-weight machine is placed on the seabed and works in water depths of up to 2000 m.
The film shots show - uncommented - tests of different components of the system in the MARUM technology hall, preparations for the suspension of MeBo on board FS METEOR, the drilling of sediment cores on the seabed and - after the return on board - the removal of the drill cores.

From BBC by Jonathan Amos

A tangle of tubes, cables, and actuators - Mebo looks as though it could morph at any moment into one of those Transformer robots from the movies. 

The 10-tonne machine is in fact a seabed drilling system, and a very sophisticated one at that.
Deployed over the side of any large ship but driven remotely from onboard, it's opening up new opportunities to take sediment samples from the ocean floor.
MeBo was developed at the MARUM research facility in Bremen, Germany, and has not long returned from a pathfinding expedition to the West Antarctic.
In the iceberg-infested waters of the Amundsen Sea Embayment (ASE), it obtained the very first cores to be drilled from just in front of some of the mightiest glaciers on Earth.
Chief among these are Pine Island Glacier and Thwaites Glacier, colossal streams of ice that drain the White Continent and which are now spilling mass into the ocean at an alarming rate.
There's concern that deep, warm water is undercutting the glaciers, possibly tipping them into an unstoppable retreat.
And that has global implications for significant sea-level rise.
It was MeBo's job to help investigate whether this really could be happening.
    • "Meeres­boden-Bo­hr­gerät" is Ger­man for "seafloor drill rig"
    • It's lowered to the seabed with a specially designed cable
    • This also delivers power, and carries commands and video
    • An operator drives MeBo remotely from the deployment ship
    • System has a magazine of pipes to lengthen the drill string 
    • Mebo can penetrate mud and rock to a depth of up to 80m

    The goal was to retrieve seafloor sediments that would reveal the behaviour of the West Antarctic Ice Sheet (WAIS) in previous warm phases.
    To read the future in the past. 
    "Has the West Antarctic Ice Sheet collapsed before? Is that the scenario we should expect in the next couple of hundred years?" pondered project leader Karsten Gohl from the Alfred Wegener Institute (AWI).
    "Perhaps in some of these warm periods it has only partially collapsed, just a few portions of it. Or maybe the WAIS was hardly affected in those times. We hope we can understand this better by collecting samples because basically the sediments are a climate archive."
    As glaciers grind their way off the continent they crush and bulldoze rock and drop it offshore.
    This material - the range of particles and their shapes, the way they are sorted, etc - codes the activity of the glaciers in the region.
    Layers deposited during periods when the WAIS was extensive will contrast with those from times when glaciers were absent or significantly withdrawn.

    "If you find ice-rafted debris (stones dropped by icebergs), for example, you can be sure there was ice on land and that the ice had advanced to the coast," explained Claus-Dieter Hillenbrand from the British Antarctic Survey (BAS).
    "But also new developments - especially what's known as geochemical provenance - have emerged in the last 10 years that mean it's even possible now to compare this material with rocks on land to pin down the actual sources in the hinterland."
    Helpfully, nature also date-stamps the sediments by incorporating the remains of single-celled organisms (foraminifera and diatoms) from the ocean.
    The distinct species that lived through different epochs act as a fossil chronometer.

    Back in Bremen: The cores have undergone CT scanning and have now been split open

    MeBo's drill cores are now back in Bremen.
    A week ago, the cylindrical liners containing some 60m of ocean-floor material were being X-rayed at a local hospital to precisely determine their internal structure.
    And in the past few days, the task began of splitting the cores to allow their contents to be fully analysed.
    The scientists who travelled to the Amundsen Sea with MeBo, on Germany's Polarstern research ship, already have some clues to what the cores will contain.
    They got a sneak preview in the rock and mud that was visible at the ends of the drill pipe segments when they were brought back up from below.
    From the 11 locations MeBo sampled, it's very likely there are sediments that record the very deep past - from the Late Cretaceous, some 70 million years ago when dinosaurs still roamed the Earth and the landmass that is now Antarctica was green.

     Ice challenge: The drill system can only be lowered when big bergs are absent 
    courtesy of T. Ronge, AWI

    Coming forward in time, it's probable also there are records from the Oligocene (34-23 million years ago) and the Miocene (23-5 million years ago) which should document some key events in Antarctica's history when a burgeoning ice sheet in the East of the continent was supplemented by one in the West.
    "We haven't got a continuous sequence; we have spot samples from these different times," explained Dr Gohl.
    "But with these sediments we hope we can establish the onset of glaciation in Antarctica, and then get records from the time in the Miocene where in other areas of the Antarctic it's known there was the main glacial advance that has persisted to today."
    With luck there are additional sediments distributed in the last few hundred thousand years, when WAIS glaciers would have advanced and retreated through the recent cycle of "ice ages".

     courtesy of T. Ronge, AWI

    What many scientists would dearly love to see is a rich record from the Pliocene, from a time three million years ago when carbon dioxide levels in Earth's atmosphere were very similar to what they are today (400 molecules of CO2 in every million molecules of dry air).
    WAIS behaviour at this time could represent the best analogue for what is about to happen to the ice sheet in the near future.
    But this desire may have to wait to be satisfied by a second expedition with a dedicated drill ship, the Joides Resolution.
    The JR can bore hundreds of metres into the seabed, increasing the chances of capturing an unabridged view of the past. A firm booking has been made for 2019.
    For now, researchers must work with the initial snapshot provided by MeBo.
    BAS team-member Bob Larter: "This is the first time we've had any real constraint on the West Antarctic Ice Sheet, because although there's been a number of drilling exercises in the Ross Sea, it's hard from that location to know for sure whether the glacial signal is coming from the East or the West. Whereas if you drill in the Amundsen Sea, you know it's a record of the WAIS."
    The results of the various lab analyses now under way are eagerly awaited and will be reported in a slew of scientific papers.
    For MeBo, the expedition has demonstrated once again what an agile system it is.
    "This type of drilling will become more common, not just in science but also in industry," predicted Marum's Tim Freudenthal.
    "There are several applications in the oil and mining industries, and offshore wind farms - they need geotechnical investigation of the seabed. For all these types of investigation, the big drilling vessels can often be too powerful. The seabed drilling systems like MeBo offer a very good alternative."
    An update on the Amundsen Sea Embayment expedition was presented to the recent General Assembly of the European Geosciences Union (EGU).

    Links :

    Thursday, June 22, 2017

    With latency as low as 25ms, SpaceX to launch broadband satellites in 2019

     SpaceX plans to launch internet satellites in 2019 to provide internet access worldwide

    From ArsTechnica by

    Satellites will function like a mesh network and deliver gigabit speeds.

    In May this year, SpaceX said its planned constellation of 4,425 broadband satellites will launch from the Falcon 9 rocket beginning in 2019 and continue launching in phases until reaching full capacity in 2024.
    SpaceX gave the Senate Commerce Committee an update on its satellite plans during a broadband infrastructure hearing this morning via testimony by VP of satellite government affairs Patricia Cooper.
    Satellite Internet access traditionally suffers from high latency, relatively slow speeds, and strict data caps.
    But as we reported in November, SpaceX says it intends to solve these problems with custom-designed satellites launched into low-Earth orbits.
    SpaceX mentioned 2019 as a possible launch date in an application filed with the Federal Communications Commission in November and offered a more specific launch timeline today.
    Cooper told senators:
    "Later this year, SpaceX will begin the process of testing the satellites themselves, launching one prototype before the end of the year and another during the early months of 2018. Following successful demonstration of the technology, SpaceX intends to begin the operational satellite launch campaign in 2019. The remaining satellites in the constellation will be launched in phases through 2024, when the system will reach full capacity with the Ka- and Ku-Band satellites. SpaceX intends to launch the system onboard our Falcon 9 rocket, leveraging significant launch cost savings afforded by the first stage reusability now demonstrated with the vehicle."

     Washington-based company Vulcan Aerospace announced that its Stratolaunch Systems, an air-launch platform for rockets, is close to completion.
    see ZDnet

    The 4,425 satellites will "operat[e] in 83 orbital planes (at altitudes ranging from 1,110km to 1,325km)," and "require associated ground control facilities, gateway Earth stations, and end-user Earth stations," Cooper said.
    By contrast, the existing HughesNet satellite network has an altitude of about 35,400km, making for a much longer round-trip time than ground-based networks.
    SpaceX has also proposed an additional 7,500 satellites operating even closer to the ground, saying that this will boost capacity and reduce latency in heavily populated areas.
    But Cooper offered no specific timeline for this part of the project.
    There were an estimated 1,459 operating satellites orbiting Earth at the end of 2016, and the 4,425 satellites in SpaceX's planned initial launch would be three times that many.
    Other companies are also considering large satellite launches, raising concerns about potential collisions and a worsening "space junk problem," an MIT Technology Review article noted last month.
    SpaceX today urged the government to relax regulations related to satellite launches and to include satellite technology in any future broadband infrastructure legislation and funding.

    Network design

    SpaceX's satellites will essentially operate as a mesh network and "allocate broadband resources in real time, placing capacity where it is most needed and directing energy away from areas where it might cause interference to other systems, either in space or on the ground," Cooper said.
    Satellites will beam directly to gateway stations and terminals at customers' homes, a strategy that will greatly reduce the amount of infrastructure needed on the ground, particularly in rural and remote areas, she said.
    "In other words, the common challenges associated with siting, digging trenches, laying fiber, and dealing with property rights are materially alleviated through a space-based broadband network," she said.
    Customer terminals will be the size of a laptop.
    While speeds should hit a gigabit per second, SpaceX said it "intends to market different packages of data at different price points, accommodating a variety of consumer demands."
    Current satellite ISPs have latencies of 600ms or more, according to FCC measurements, but SpaceX has said its own system will have latencies between 25 and 35ms.
    That's better than DSL and similar to several of today's major cable and fiber systems, according to FCC measurements.
    The measurements show that the Altice-owned Optimum and Verizon FiOS had latencies of just over 10ms, better than what SpaceX is expecting to achieve.
    SpaceX promised that its satellite technology won't become stale after launch.
    The company's "satellite manufacturing cost profile and in-house launch capability" will allow it to continually update the system's technology to meet changing customer needs, Cooper said.

    Links :


    Wednesday, June 21, 2017

    Image of the week : happy summer solstice

    06:24 UTC today marked the Summer Solstice 2017
    as seen in this image from our Meteosat-10 geostationary

    Happy Summer Solstice!
    Your shortest shadow of the year will be on show at noon.
    Pic shows light/dark tilt in satellite data from 8am today.
    From Eumetsat
    The summer solstice (or estival solstice), also known as midsummer, occurs when a planet's rotational axis, or geographic pole on either its northern or its southern hemisphere, is most inclined toward the star that it orbits.
    On the summer solstice, Earth's maximum axial tilt toward the Sun is 23.44°.
    (Likewise, the Sun's declination from the celestial equator is +23.44° in the Northern Sky and −23.44° in the Southern Sky.)
    This happens twice each year (once in each hemisphere), when the Sun reaches its highest position in the sky as seen from the north or south pole.

    The summer solstice occurs during the hemisphere's summer.
    This is the northern solstice in the Northern Hemisphere and the southern solstice in the Southern Hemisphere.
    Depending on the shift of the calendar, the summer solstice occurs some time between June 20 and June 22 in the Northern Hemisphere and between December 20 and December 23 each year in the Southern Hemisphere.
    The same dates in the opposite hemisphere are referred to as the winter solstice.

    As seen from a geographic pole, the Sun reaches its highest altitude of the year on the summer solstice.
    It can be solar noon only along that longitude, which at that moment lies in the direction of the Sun from the pole.
    For other longitudes, it is not noon.
    Noon has either passed or has yet to come.
    Hence the notion of a solstice day is useful.
    The term is colloquially used like "midsummer" to refer to the day on which solstice occurs.
    The summer solstice day has the longest period of daylight, except in the polar regions, where daytime remains continuous for 24 hours every day during a period ranging from a few days to six months around the summer solstice.

    It's World Hydrography Day : what is hydrography?

    Wednesday 21st of June is World Hydrography Day as declared by the United Nations.

     Hydrography is the science that measures and describes the physical features of bodies of water.
    By mapping out water depth, the shape of the seafloor and coastline, the location of possible obstructions, and physical features of water bodies, hydrography helps keep our maritime transportation system moving safely and efficiently.
    source : NOAA / NGA 

    The weather master

    An In-Depth Look at the Finite­ Volume Cubed-Sphere Dynamical Core (FV3)

    From ScienceMag by Paul Vousen

    Take that, Europe.
    Computer modeler aims to give U.S. lead in weather predictions :

    Shian-Jiann “S. J.” Lin’s program will power short-term weather forecasts and long-term climate simulations.

    From below the conference table comes the thrum of incoming phone alerts.
    The new weather forecast has rolled in, and the climate scientists, even though it’s not typically their business, dig out their phones to look: snow tomorrow—hardly unusual for early February in Princeton, New Jersey.
    But the weather models have the storm breaking severe, dumping a foot or more.
    A snow day seems likely.
    Across the table at the Geophysical Fluid Dynamics Laboratory (GFDL), Shian-Jiann “S. J.” Lin is not convinced.
    He is the master of 20,000 lines of computer code that divide the atmosphere into boxes and, with canny accuracy, solve the equations that describe how air swirls around the globe.
    For decades, Lin’s program has powered the long-term simulations of many climate models, including GFDL’s—one of the crown jewels of the U.S. National Oceanic and Atmospheric Administration (NOAA).
    Now, Lin’s domain is expanding to a different side of NOAA: the short-term weather forecasts of the National Weather Service (NWS).

    By 2018, Lin’s program will be powering a unified system for both climate and weather forecasting, one that could predict conditions tomorrow, or a century from now—and do it faster and better than current models.
    His work will soon be guiding mayors planning not just for snow plows, but also rising seas.
    But Lin has started early.
    His small team is already running a prototype forecast on their supercomputer.
    And in his typically confident and brash style, he offers a minority report about the next day’s storm.
    “If our forecast is correct, it’s only 3 to 6 inches,” Lin announces. His peers at the table seem skeptical.
    “It’s going to be a mess,” one warns.
    But Lin doesn’t budge.
    He rarely needs to.
    “We’ll see what we get tomorrow,” he says.
    “You want to bet?”
    Much is riding on Lin.

    NOAA'S new weather satellite expected to lead to more accurate forecasts.
    The first set of images from the GOES-16 satellite have been released by National Oceanic and Atmospheric Administration (N0AA).
    The geostationary satellite will be used for weather forecasting, severe storm tracking and more. 

    Recently, NWS has suffered some prominent embarrassments, such as in 2012, when it predicted Hurricane Sandy would sputter out over the ocean while a leading European center accurately forecast the direct hit on New York City.
    Fed up with the country’s second-place status, Congress in 2013 poured $48 million into NWS weather modeling.
    The message for NOAA was clear: Get America on top.
    This drive has opened up an opportunity.
    For a long time, meteorologists and climate scientists operated in separate domains.
    Meteorologists focused on speed: ingesting as many data as possible from satellites, balloons, and buoys and quickly spinning it into a forecast.
    Climate scientists focused on the fussy physics of their models to produce plausible simulations over decades.
    But now, the two groups are discovering common ground, in “subseasonal to seasonal” predictions—from a month to 2 years out.

    In order to push forecasts beyond 10 days or so, meteorologists need the superior physics of the climate models.
    Meanwhile, climate scientists want to know how weather phenomena that happen on monthly or annual timescales, like El Niño, influence the global climate.
    “The two cultures are speaking each other’s language, and realizing they’re going to live and die together,” says John Michalakes, a computer scientist who develops atmospheric models at the Naval Research Laboratory in Monterey, California.
    There could be another benefit to blurring the lines between weather and climate, one that climate scientists are loath to talk about explicitly.
    Although studies of human-driven climate change have faced scrutiny and scorn from conservative politicians in the United States, weather research remains solidly bipartisan, says David Titley, director of the Center for Solutions to Weather and Climate Risk at Pennsylvania State University in State College.
    Just this month, for example, Congress passed a weather forecasting bill that dedicates $26.5 million of NOAA’s budget to improving its seasonal predictions, and climate change doubters were among the supporters.
    “If I were running the world, I would keep that divide vague,” Titley says.
    In his modeling, Lin never made the distinction.
    “From the beginning we talked about how there is no difference between weather and climate,” says Ricky Rood, an atmospheric scientist at the University of Michigan in Ann Arbor and Lin’s longtime collaborator.
    But others haven’t wanted to hear that message—and especially not from Lin, who is as feisty and fractious as a government employee can get.
    “It’s amazing to me,” says Rood, “that S. J. could evolve to be a source of unification.”
    Storms have roiled around Lin his whole life.
    Typhoons are regular events in Taipei, where he grew up, and he was always fascinated by their power.
    “I have hurricanes in my blood,” he says.

    Born in 1958 to parents who ran a small construction company, he was the first in his family to go to college.
    As a student at National Taiwan University, he studied microprocessor architectures, along with meteorology and fluid dynamics.
    He became fascinated with the challenge of rendering the continuous currents of the atmosphere in the discontinuous, 0-or-1 world of computer code.
    At the time, Taiwan was a dictatorship, and Lin joined student groups opposed to the regime.
    After college, he faced several years of mandatory military service.
    He aced his entry test and assumed he would land a cushy engineering job in Taipei.
    Instead, he was shipped to the Matsu Islands, 16 kilometers from the Chinese mainland.
    He was hardly a model soldier.
    He hated having to recite party doctrine during assemblies.
    “You had to pretend, and say something not in your heart,” he says.
    Taiwan didn’t seem to have a place for him, so in 1983 he enrolled in the aerospace engineering department at the University of Oklahoma, one of the only schools he could afford.
    He wanted to be a rocket scientist.
    But it was a tough transition.
    He cared more about learning computer languages than English, and felt isolated.
    His accent is a barrier, but not the only one.
    “Some folks tend to have a difficult time following S. J.,” says Bill Putman, a meteorologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and another longtime collaborator.
    “But it’s not necessarily a language barrier.
    It’s more a knowledge barrier.”

    Seeing his talent for computational fluid dynamics, his adviser suggested Lin switch to Princeton University, which with its partnership with GFDL is a hotbed for atmospheric modeling.
    He learned how GFDL scientists divided the air into a 3D grid that spanned the globe and stretched from the surface to the stratosphere, following lines of latitude and longitude.
    Along points on the grid, they would set initial conditions—the weather or climate for a given moment in time.
    Then, point by point, the computer would solve equations describing changes in wind, air pressure, temperature, and humidity for successive steps in time.
    Computers were room-sized mainframes at the time, and the model grids were huge, with a mesh size of 500 kilometers.
    The models could recreate only the largest atmospheric features, like jet streams and the Hadley cell, the belt that circulates warm air from the equator to the subtropics.

    After graduate school, Lin decided to stay in the United States.
    “I’m now more American than I am Taiwanese,” he says.
    He drinks whisky, but infuses it with ginseng.
    He returned to the University of Oklahoma as a postdoc to work on modeling tornadoes.
    But computers couldn’t yet model events that unfold at such small scales.
    The failure was humbling, and Lin says it provided a mantra: “Choose the right level of complexity for the particular problem, at the time that you have the resources to do it.”
    Lin soon found the right problem at NASA.
    In the late 1980s, Rood was working on the problem of the Antarctic ozone hole at Goddard.
    NASA was flying research planes into the hole to measure the chemicals that might be destroying it.
    These flights revealed a drop in several short-lived reactive nitrogen oxides, which allowed chlorine from human-made chemicals to linger, priming further reactions that broke down the ozone.
    But Rood’s atmospheric models couldn’t simulate the flows and reactions.
    No matter what he did, the nitrogen reactants remained steady.
    How could that happen?
    At the time, an elegant mathematical solution had overtaken global modeling, called the spectral method.
    Rather than solving at points on a latitude-longitude grid, scientists realized that fluid flow in the atmosphere could be represented as the sum of a series of hundreds of sinusoidal, crisscrossing waves.
    The code ran faster, and the results could be transformed back onto a regular grid.
    The spectral method still powers most global weather forecasts today, including at NWS.
    But the speed comes with a cost: When the waves are projected back into physical space, mass can gradually grow unbalanced.
    For weather models, which only run for days into the future, this is not a big deal.
    But for models of atmospheric chemistry and climate, which run for much longer periods, these distortions were a critical flaw.

    Fortunately for Rood, a young Taiwanese scientist had written to him, lured by his publications.
    When Lin joined NASA in 1992 as a contractor, the two set out to build a model that, above all else, preserved mass.
    This first meant jettisoning the spectral method.
    It also meant upgrading from finite-difference modeling, which solves for points on a grid, to a finite-volume model, which solves for conditions averaged across each cell, or box, and is ideally suited for conserving mass because the calculations pass fluxes, or volumes, of material from one box to the next.
    Others had considered such a solution, but thought it too complex or computationally expensive.
    But Lin was a master of computational efficiency.
    Over a furious few years in the mid-1990s, he and Rood expanded their model beyond chemical transport—for which it remains the standard—to a fullfledged dynamical core fast enough to be used for climate models.
    Put a mote of dust in the air, says Paul Ginoux, an aerosol modeler at GFDL, who also worked with Lin at Goddard, “and this code will transport it at the right place, at the right moment.
    And that’s beautiful.” The name of the code was far more mundane.
    They called it “FV,” for finite-volume, and later FV3.
    Their work soon drew the attention of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, one of the country’s leading institutes for weather and climate science, which incorporated FV into its influential climate model.
    NASA’s climate laboratory in New York City adopted it as well.

    And in 2003, GFDL lured Lin away to upgrade FV and fold it into its global simulation.
    The results of these models, some of the top U.S. contributions to the United Nations panel on climate change, have informed much of what the public hears about global warming.
    And they’ve all had Lin’s innovations at their heart.
    There's a term of art at NOAA for the reactive way Congress finances weather research: “budgeting by disaster.” It’s rarely pretty, and it’s why the coming merger in atmospheric modeling will, at its root, be thanks to the calamities of Hurricane Katrina and Hurricane Sandy.
    In 2005, after NWS failed to forecast Katrina’s direct hit on New Orleans, Louisiana, until 2 days out, Congress set aside money to improve predictions of Atlantic hurricanes.
    As it happened, it was around this time that Lin walked into the office of his boss at GFDL, Isaac Held, and declared: “I’m going to revolutionize weather prediction.” Computers were now capable of processing boxes small enough to render hurricanes.
    More important, Lin had developed a key bit of physics needed for FV3 to forecast realistic hurricanes.
    Many global forecasting models operate using an assumption called the hydrostatic principle—where the gravity of the air in any box is exactly balanced by the upward force of the air pressure in the box below it.
    This works for coarse models, which cannot directly simulate the fine upward and downward flows in the real atmosphere.
    But recreating weather events like hurricanes and thunderstorms, where updrafts are important, requires breaking this hydrostatic principle.
    After a decade of mulling, Lin finally had an efficient way of incorporating nonhydrostatic flows into his code.
    He needed to test it.


    Zooming in on storms
    The FV3 model divides the atmosphere into boxes and simulates conditions in each one.
    To avoid problems at the poles, its coordinates are based on a cubed sphere.
    The program can also nest grids to simulate weather at different scales.
    Frank Marks, who leads hurricane research at NOAA’s Atlantic Oceanographic and Meteorological Laboratory in Miami, Florida, was overseeing improvements for the regional hurricane model for the Atlantic basin.
    With a smaller area to model, Marks can afford to have fine-scale boxes.
    Lin convinced him to use Katrina dollars to buy extra supercomputer time.
    Run FV3 at a 1-kilometer resolution, Lin promised, and the finest details of cyclones would arise.
    Sure enough, the violent walls of a hurricane’s eye opened in his code.
    In 2014, when NOAA announced a competition to choose the “core” of the agency’s next-generation weather forecast system, Lin was ready.
    Five models were entered, including FV3.
    And by the summer of 2015, FV3 was one of two frontrunners, along with the Model for Prediction Across Scales (MPAS), the globalized version of a long-standing system produced by NCAR and used by many researchers.
    They would be judged on their speed and accuracy in mimicking the atmosphere’s flows.
    For 6 months, Lin’s placid office turned frenetic, as his team worked nights and weekends to embed FV3 within the weather service’s system.
    “There was never a time where I thought we were losing the battle on scientific ground,” Lin says.
    One advantage of his model was efficiency. It is Lin’s obsession—and not just at work: When Hurricane Sandy knocked out power at Lin’s modest home, he refused to use a normal generator, and instead rigged his Prius up to his home wiring.
    Its battery, he explained, would make certain any extra electricity the car’s generator churned out wouldn’t go to waste.
    So that FV3 could make efficient use of limited computing power, Lin and his team had written the code to work in parallel.

    This is hard for global models, where the weather in one box can influence another box a hemisphere away.
    But this interconnectedness isn’t as big a problem in the vertical dimension, so Lin enabled FV3’s layers to be detached from each other and be processed in parallel.
    He won additional efficiencies by changing the shape of the grid.
    Climate models are plagued by the so-called pole problem, the result of the strangely squished and stretched boxes near the poles.
    So Lin and Putman, his former NASA colleague, abandoned the latitude/longitude system in favor of a cubed sphere.
    Picture a six-sided die inflated like a balloon.
    There were no more poles to handle, just six square panels, with tricky interactions at the seams.
    The net result: compared with MPAS, FV3 took a third as many computer processors to run at operational standards.
    It also outperformed MPAS when run on a vast number of processors, and it could zoom in to model one part of the globe at high resolution without skewing its performance in coarser regions.
    It was a slaughter.
    NCAR withdrew its model before NOAA anointed FV3 as the winner, in July 2016.
    “There was just never any conclusive evidence that MPAS had an advantage that was worth the cost,” says Michalakes, who led the computing comparisons.
    During the competition, Lin had complained that NOAA was biased in favor of MPAS; now, he crows about his victory.
    “Most people in that discipline paid no respect to what we had been doing,” he says.
    “They found out the hard way.” With NCAR toppled, Lin now faces far bigger rivals: the United Kingdom’s Met Office, which since the early 1990s has been the only center to have merged its weather and climate forecasts, and the European Centre for Medium-Range Forecasts, which has long run the top-rated weather model.
    This time around, he’ll need help.

    European modelers start with the same set of balloon, satellite, and ground measurements as everyone else.
    But they cleverly inject randomness into these initial conditions, then do multiple runs to come up with a “consensus” forecast.
    Getting the United States up to those standards will require winning over U.S.
    researchers to provide innovative techniques that Lin and his colleagues can adapt for their model.
    Yet there’s a risk that academic weather scientists will avoid using FV3 and instead stick with MPAS, more comfortable with its origins and documentation, says Cliff Mass, an atmospheric scientist at the University of Washington in Seattle.
    Lin’s reluctance to break down his code in the past has heightened concerns.
    “Lin is a brilliant modeler,” Mass says.
    “He’s not big on community support.” But Putman believes Lin will embrace true improvements.
    “If he sees something that will push this code beyond where it is now, I’m sure he’s willing to adapt.”
    At a workshop next week, NWS will lay out its aggressive timetable for turning on FV3.
    By this May, FV3 ought to be fully wired into the service’s data assimilation.
    And by the first half of 2018, if all goes well, NOAA will flip the switch, making it the standard forecast that feeds into all of our phones.
    Meanwhile, Lin’s team continues to tinker with FV3.
    They’re honing a more powerful zooming technique: allowing the grid to create nests of high-resolution boxes, 2 to 3 kilometers a side, over regions of interest.
    This could allow high-resolution hurricane forecasts to be run at the same time as global predictions, with no need to wait for the global run to finish.
    And it could capture tornado outbreaks and severe storms, weather that has been too finegrained for existing global models.
    “We’re kind of ambitious,” Lin says.
    “We’re trying to cover everything.”

    On a screen at GFDL, Lucas Harris, Lin’s deputy, zooms in on Oklahoma, where a nested FV3 grid is recreating the events of May 2013.
    It was that month that a severe twister plowed through Moore, Oklahoma, killing 24.
    As the model runs, scattered storms organize into a line of squalls.
    Then anvil clouds form—the thunderstorm cells from which tornadoes would touch down on Moore.
    Next, Harris changes the place and time, to the eastern United States in June 2012, when a bow of thunderstorms—a so-called derecho—caught forecasters off guard and in some areas knocked out power for a week.
    The model sees traces of the storm nearly 3 days in advance.
    “Previously,” Harris says, “it was believed there was only 12 hours of predictability to this event.”
    So far these results have stayed in the lab, but Lin is doing his best to spread the gospel.
    For the 2017 hurricane season, his prototype will run alongside existing regional hurricane models.
    And next month, Lin will return to Oklahoma for the “Spring Experiment,” a research jamboree of severe storm scientists, to test how the zooming technique could help local forecasters.
    All this collaboration, this dependence on outside contributions, makes Lin nervous.
    His model is moving out of the lab into the messy real world.
    Will it become the bedrock of all weather and climate prediction, from tornadoes next week to temperature rises next decade? “I’m cautiously optimistic, but not overly optimistic,” he says.
    A good omen comes the next morning.
    Snow blankets Princeton—beautiful, but also manageable.
    Nearly 6 inches fell, not a foot or more.
    GFDL could have stayed open.
    Over the ether, Lin can’t resist a final comment.
    “The snow,” he writes, “is not as bad as forecasted.”

    Links : 

    Tuesday, June 20, 2017

    First nautical chart designed for bathymetric navigation

    In 1939, Coast Survey published the first chart designed for bathymetric navigation.
    Chart 5101A uses 50-fathom depth curves and fewer numerical depths.
    The resulting product brings out steep slopes and broad plateaus of the bottom topography

    zoom on chart 18740 nautical raster chart in the GeoGarage platform

    Monday, June 19, 2017

    New map reveals ships buried below San Francisco

    Cartographers are still putting the finishing touches on the new map, which will appear in the visitors’ center at the San Francisco Maritime National Historical Park.
    This detail from a new map of buried ships in San Francisco shows the original shoreline extending inland to the current location: the iconic Transamerica Pyramid building (top center).
    From National Geographic by Greg Miller

    Dozens of vessels that brought gold-crazed prospectors to the city in the 19th century still lie beneath the streets.

    Every day thousands of passengers on underground streetcars in San Francisco pass through the hull of a 19th-century ship without knowing it.
    Likewise, thousands of pedestrians walk unawares over dozens of old ships buried beneath the streets of the city’s financial district.
    The vessels brought eager prospectors to San Francisco during the California Gold Rush, only to be mostly abandoned and later covered up by landfill as the city grew like crazy in the late 1800s. Now, the San Francisco Maritime National Historical Park has created a new map of these buried ships, adding several fascinating discoveries made by archaeologists since the first buried-ships map was issued, in 1963. It’s hard to imagine now, but the area at the foot of Market Street, on the city’s eastern flank, was once a shallow body of water called Yerba Buena Cove, says Richard Everett, the park’s curator of exhibits.
    The shoreline extended inland to where the iconic Transamerica Pyramid now rises skyward.

    In 1848, when news of the Gold Rush began spreading, people were so desperate to get to California that all sorts of dubious vessels were pressed into service, Everett says.
    On arrival, ship captains found no waiting cargo or passengers to justify a return journey—and besides, they and their crew were eager to try their own luck in the gold fields.

    This is one of five panels in a panoramic daguerreotype taken by William Shew in or around 1852. Rincon Point, the southern end of the cove, appears in the foreground. 

    The ships weren’t necessarily abandoned—often a keeper was hired to keep an eye on them, Everett says—but they languished and began to deteriorate.
    The daguerreotype above, part of a remarkable panorama taken in 1852, shows what historians have described as a “forest of masts” in Yerba Buena Cove.
    Sometimes the ships were put to other uses.
    The most famous example is the whaling ship Niantic, which was intentionally run aground in 1849 and used as a warehouse, saloon, and hotel before it burned down in a huge fire in 1851 that claimed many other ships in the cove.
    A hotel was later built atop the remnants of the Niantic at the corner of Clay and Sansome streets, about six blocks from the current shoreline (see map at top of post).

    Localization with the GeoGarage platform (NOAA chart on Google Maps)

    A few ships were sunk intentionally.
    Then as now, real estate was a hot commodity in San Francisco, but the laws at the time had a few more loopholes.
    “You could sink a ship and claim the land under it,” Everett says.
    You could even pay someone to tow your ship into position and sink it for you.
    Then, as landfill covered the cove, you’d eventually end up with a piece of prime real estate.
    All this maneuvering and the competition for space led to a few skirmishes and gunfights.

    One of these intentionally scuttled ships was the Rome, which was rediscovered in the 1990s when the city dug a tunnel to extend a streetcar line (the N-Judah) south of Market Street.
    Today the line (along with two others, the T and the K) passes through the forward hull of the ship.
    Eventually Yerba Buena Cove was filled in.
    People built piers out into it to reach ships moored in deeper water, Everett says.
    “The wharves are constantly growing like fingers out from the shore.”
    Then people began dumping debris and sand into the cove, which was only a few feet deep in many places to begin with.
    “By having guys with carts and horses dump sand off your pier,” Everett says, “you could create land that you could own.”
    It was a land-grab strategy with lasting ramifications—as evidenced by the ongoing controversy over a sinking, tilting skyscraper built on landfill near what was once the southern edge of Yerba Buena Cove.
    Three archaeologists—James Allan, James Delgado, and Allen Pastron—consulted on the making of the new shipwreck map, and discoveries by them and their colleagues have added several fascinating details that weren’t on the original buried-ships map created by the San Francisco Maritime National Historical Park in 1963 (see below).
    Red circles on the new map indicate sites that have been studied by archaeologists.

    This detail from the original 1963 buried-ships map shows “Sydney Town,” where Australians congregated in Gold Rush days.
    There was a Chilean enclave just inland from here, and fights sometimes broke out between the two groups.
    Map courtesy San Francisco Maritime National Historical Park 

    One of the most interesting additions to the new map is a ship-breaking yard at Rincon Point at the southern end of Yerba Buena Cove, near the current anchorage point for the Bay Bridge.
    A man named Charles Hare ran a lucrative salvage operation here, employing at least 100 Chinese laborers to take old ships apart.
    Hare sold off brass and bronze fixtures for use in new ships and buildings.
    Scrap wood was also a valuable commodity in those days, Everett says.
    The 1851 fire ended Hare’s business.
    Archaeologists have found the remnants of six ships at the site that were presumably in the process of being salvaged at the time of the fire. One—the Candace—was another whaling vessel pressed into service to bring gold-crazed prospectors to San Francisco.
    A lighter, small, flat-bottomed boat that was used to shuttle goods from moored ships to shore has also been found.A development project near Broadway and Front streets, which began in 2006, turned up bones that archaeologists suspect came from Galapagos tortoises (the site is marked by an asterisk in the map at the top of this post).
    After passing around Cape Horn, many ships stopped in the Galapagos Islands and threw a few turtles in the hold—a source of fresh meat for the long voyage north to California.
    “They got to San Francisco, and lo and behold: They had more turtle than they could eat,” Everett says.
    Menus from the era show that turtle soup was a common offering at restaurants and lodging houses around the cove.

    Illustrator and designer Michael Warner says his inspirations for the new map included the “Maps of Discovery” from a mural painted by N.C. Wyeth in 1928 for the headquarters of the National Geographic Society.
    Wyeth’s imaginative painting evokes the romance of the Age of Discovery, and Warner says it inspired him to go beyond just showing the details of the buried ships and historic wharves.

    “My hope is that I have not only enhanced the image for the history enthusiast,” he says, “but created something that might even make people learn by accident!”
    The team is still ironing out some final details, such as how to most accurately represent the boundaries of Charles Hare’s ship-breaking yard.
    They hope to have posters of the new map available for purchase early next year and plan to eventually put it on display in the visitors’ center.

    Links :

    Sunday, June 18, 2017

    Yacht race starts from Plymouth (1964)

    The boats with full sails head out to the bay
    for the start of the second edition of the single handed Transatlantic yacht race (OSTAR)
    (May 23, 1964)
    Thirteen competitors started this race in 1964, 
    which by now was firmly established on the racing scene.
    All of the five original competitors entered, and all five improved their original times (Gipsy Moth III with Sir Francis Chichester the winner of the first edition in 1960 making ready);

    but the show was stolen by French naval officer Éric Tabarly, who entered a custom-built 44-foot (13 m) plywood ketch, Pen Duick II.
    The days of racers sailing the family boat were numbered following Tabarly's performance, for which he was awarded the Légion d'honneur by president Charles de Gaulle.
    It is also noteworthy that Tabarly and Jean Lacombe were the only French entrants in this race; Tabarly's success was instrumental in popularising the sport in France, the country which in future years would come to dominate it.

    This was to be the year in which several future trends were established.
    Multihulls made their first appearance — sailing in the same class as the other boats; and the race featured the use of radio, for the first time, by several competitors who gave daily progress reports to their sponsors.

    Links :