Posts by malcolmus_rex 22 publicly visible posts • joined 10 Apr 2008
Top 500 is out today: http://www.top500.org/list/2016/06/
The phase 1 systems (so not the bulk of the compute), comes in at 29 and 30. That beats all of the other meteorology HPCs, except ECMWF.
For a forecast postion of 25 (range 10 to 30), coming in at 29 & 30 is not a bad forecast! ;-)
The calculation of the position in the Top500 in 2017 seems to have been done by looking at the Top500 perfromance development charts ( http://www.top500.org/statistics/perfdevel/ ). In Feb 2017, the number 1 slot is projected to be 236Petaflops and the number 500 slot 1.4PF.
Putting 16PF in at number 250 is a bit strange, as the distribtuion of the Rmax in any Top500 list is very non-linear, with a small number of very powerful machines (which are used for applications that happen to score high on the linpack metric) and a long tail lower scoring machines (that are either smaller, or built for applications which don't score well on the linpack metric). Using the distribution of the most recent list (http://www.top500.org/statistics/efficiency-power-cores/ and change the chart type to Rmax), this new machine has an Rmax of 16PF, which is 10x the bottom, which I would guess comes in approximately at number 25. Using older lists, this exact number changes a bit, but it's fairly robust between number 10 and number 30.
I wouldn't call that "VERY AVERAGE".
I don;t know about the US vehicle taxation, but in the UK it's just plain wrong to say that it's car drivers that pay for the roads.
In the UK, most roads are maintained by local councils, using funding from council tax. Cyclist pay rhan.
The motorways and major roads are paid for out of central taxation.
Vehicle Excise Duty brings in approx £5bn per year (to central taxation). The road building program was approx £15bn last year, so cyclists are subsidising drivers.
I suspect that the situation isn't that different in the US.
My (limited) understanding is that GPGPU hardware isn't good enough for interprocessor communication for high resolution weather forecasting to work well. This sort workload needs a lot of compute but also, inhernently, alot of comms between the compute. That's a major bottleneck.
You can bet it's been tried and tested, and it's an exciting avenue for research. For actual usage, not just yet, maybe next time.
Also, on FORTRAN, it's probalbly here to stay in HPC and scientific computing for a long time yet. A nice discussion is here:
http://arstechnica.com/science/2014/05/scientific-computings-future-can-any-coding-language-top-a-1950s-behemoth/1/
The growth of Antarctic coverage is occurring at a much slower rate compared to the Arctic sea ice decline.
http://nsidc.org/cryosphere/seaice/characteristics/difference.html
So the increase in the albedo of Antartic sea ice is more than offset by the reduction in the albedo of the Arctic (after accounting for the Antarctic sea ice being further from the pole, so receiving more incoming solar radiaiton).
You're right that there was an observed warming over the US after 9/11, indicating that the contrails had a cooling impact (e.g. http://www.nature.com/news/2008/081231/full/news.2008.1335.html#B1 ).
It's worth pointing out that this is not inconsistent with the results of this study, or convential climate science.
As explained in the article, the impact of contrails can be either a cooling by reducing the amount of sunlight (SW radiation) reaching the ground, or a warming due to the interception of infrared (LW) radiation leaving the Earth.
The SW effect is strongest during the day, especially in the Tropics or in Northern/Southern hemisphere in their respective Summers.
The LW impact is occurring all the time, all day and throughout the year. It is stronger over warm surfaces where there is more upwelling LW to start with. It dominates over the SW effect at night, and in Winter.
The impact of both the LW and SW effects are reducing by the precence of other natural clouds. This is hard to determine though, as some contrails grow into large sheets of cirrus clouds, which wouldn't have formed without an initial contrail to get them started (because ice clouds need to an ice nuclei to get them started).
The balance of the impact of contrails depends very strongly on their spatial and temporal distribution, which means that adding up these two impacts is quite hard to do.
The researchers in this case have tried to do this, and shown that the net impact is a warming. This is consistent with previous studies.
September, over the US, is only just in the Autumn/Fall, so there's still a lot of sunlight coming in and the SW cooling dominated over the LW warming. If the same thing had happened in January or Febuary then it's very likely that there would have been a warming.
Because of the seasonality there could be a more nuanced message than just 'avoid contrails', which is what comes across in the Reg(+other) article. That would be to seriously avoid contrails in Winter in mid-latitudes, but that contrails in Summer or the Tropics are OK.
The paper in question doesn't actually say 'avoid all contrails' but instead "We have developed a simple framework to enable the trade-off between contrail and CO climate impacts to be estimated for a single flight.". So they've developed a methodology to see which contrails should be avoided, and which ones aren't.
I'm just wondering, could the heartbleed bug, and it's discovery, be in any way related to the discovery of the windigo botnet?
http://www.theregister.co.uk/2014/03/18/windigo_unix_botnet/
This was a botnet of linux/unix servers, where hackers gained access to ssh credentials and installed nefarious versions of ssh... but how did the hackers get access???
Any thoughts anyone?
The gaming issue, and this specific paper aside, your take on meta studies is wrong. When looking at small changes which are hard to detect then you need a very large sample size in order to determine any reliable signals. A well conducted meta studiy give you this in a way that no other approach can.
Google the Cochrane Library, and read Ben Goldacre's 'Bad Pharma' - meta studies are the gold standard when it comes to medical evidence, and have saved thousands of lives and millions of dollars/pounds. It's individual studies that need to be regarded with suspician.... That's where the bullshit lies.
Fusion is vert important and people are funding it.
It works on a small scale, but at that scale it needs more energy input that it produces.
That will hopefully change, with two multi-billion dollar international research projects looking into it:
http://www.iter.org/
https://lasers.llnl.gov/
It turns out that using fusion to make electricity is actually quite difficult.
"Try living abroad for a while, and suddenly you'll stop taking the BBC for granted."
I couldn't agree with you more - living in the USA for a year was a real eye opener regarding the quality and value for money of the BBC. The mere fact that it exists means that that the commercial broadcasters can't sink as low as theyd like too in terms of program quality and news reporting. This benefits everyone who lives in the UK, and I think it's the real reason that Murdoch/Sky hates the BBC so much.
There's no production grade studio camcorders yet - but when WebM is available on pretty much every computer, either directly or as an IE plugin, then manufacturers realise they can add WebM as an optional format FOR FREE... and allow a significant increase in the number of hours recording they can fit on the memory stick*, then It won't be long before WebM is available on every new camcorder...
* I know it's totally unscientific, and only a single device, but I was playing around, converting my home videos from H.264 to WebM and the files shrank by anything from a factor of 25% to 50% without loss of quality.
AC 15:24 is correct, aeroplanes (and cars) don't just emit CO2, they also emit NOx (NO which reacts to form NO2, which breaks down in sunlight to form NO and other noxious nasties. The steady state of NO and NO2 is referred to as NOx). At high altitudes NOx is a more effective greenhouse gas (because there isn't usually very much up there).
Still, even including for this effect, the total effect of aviation emissions is small compared to domestic/industrial energy supply and ground transport.
It's very true that aviation emissions will be a problem, but they're a problem only when we've got our non-CO2-emitting nuclear power stations (or tidal barrages and wind/solar power farms totally covering the land) which generate enough CO2 free electricity for domestic/industrial use and supply electric/hydrogen cars instead of that pesky internal combustion engine. As that starts to happen then we'll need to get serious about reducing aviation emissions... By that time the aviation industry will probably have devised a technical solution to the problem by have much more efficient aircraft and/or novel fuel sources.
Until then, we need to get our priorites straight and concentrate on on where most of our emissions actually come from. Energy supply.
This obsession against cheap flights does have a whiff of snobbery to me... it's also a dangerous displacement activity, by not flying people think they're eco-angels... but they still drive to work when they could cycle or take the train... and both at work and at home they're using electricity and heating mostly from fossil fuels, but they think they've done their bit...
In my experince of the HPC crowd, most of the HPC people are people who have been grad students, and whille they were grad students they learned unix/linux and learned to love it.
The thing they actually bitch about isn't the need for super-geeks who do the optimisations and administration etc. it's how to get their programs to run faster, so work churns through the queues faster and they actually get to do their work (rather than sitting at their desks, reading the reg while stuff waits/compiles).
My guess is that the windows for HPC (like the Cray X1) will make a couple of big sales and headlines, then people will figure out that if they wipe the system and put linux on it then their queues run 10% (or knowing Redmond, 2x or 3x faster) and they'll switch in a flash.
Tropical Storms are only called Hurricanes when they're in the Atlantic and the Eastern Pacific. They're always called cyclones when they're in the Indian Ocean and Typhoons in the Western Pacific Ocean.
These are all the same phenomena; the differences are linguistic rather than meteorological.
A local area model running on a desktop is also a not doing anything clever - a local area model that's of any use has a resolution that's so much higher than a global model that it also needs a supercomputer. In fact it generally takes longer to run a good mesoscale model than it does to run a global one.
Then there's the computer resources needed to process GB upon GB of observation data from all the different satellites, radar, weather stations and balloons etc. to produce a good starting point for the model. That should be done by a good mesoscale model too and is computationally expensive (and for a global model it's very very expensive indeed).
Then to give a much better forecast, to get around the butterfly effect, many different forecasts can be run each with very slightly different starting conditions (within the errors of the observations). This ensemble of model forecasts can be used to quantify the probability of events occurring... It's particularly useful for severe weather events. Of course it also multiplies the computer cost by however many model runs you can do but the civil contingency people and utilities companies will pay good money for this. Sadly this sort of stuff never makes it to the BBC weather forecasts or the weather websites. There's a perception that the public are just too dumb to understand it (and they may be right: http://www.theregister.co.uk/2007/11/08/scratchcard_anarchy/ ).
Of course those smaller companies you mention might not actually have a better forecast but I'd bet good money that they're able to disseminate the information they get from their forecasts in a more useful (and profitable) way than many of the bigger organisations.
So, Martin, you work for a Meteorology company. I assume that means that your company sell forecasts based on publicly available forecast data... where do you think that data comes from if it's not from one of the National Weather Services with a great big supercomputer?
Here's the supercomputers in meteorological organisations currently in the Top 500 list:
67 ECMWF
68 ECMWF
72 Korea Meteorological Administration
141 China Meteorological Administration
197 Japan Meteorological Agency
198 Japan Meteorological Agency
219 NOAA/Geophysical Fluid Dynamics Laboratory (GFDL)
232 Beijing Meteorlogical Bureau
246 Fleet Numerical Meteorology and Oceanography Center
410 Fleet Numerical Meteorology and Oceanography Center
The chances are that your meteorology company get's its data from number 219, or from the UK Met Office (whose supercomputer has dropped off Top 500 list until gets a new one..)
Climate models don't need much CPU or RAM. A weather forecasting model needs alot of both. 8GB of ram really doesn't come close....
Fred - you are missing something....
The CO2 released from burning wood was absorbed from the atmosphere at some point in the last 10-100 years. That means that burning wood isn't going to have an impact on the amount of CO2 in the atmosphere as it's just releasing CO2 that has only recently been absorbed (in geologic time anyway). That's what is usually meant by a carbon neutral fuel source.
The CO2 released from burning coal (and all fossil fuels) was absorbed from the atmosphere hundreds of millions of years ago. The atmosphere and climate has long since readjusted to not having that carbon around, so by burning coal you increase the concentration of CO2 in the atmosphere.
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