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Messages - Wipneus

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4051
Arctic sea ice / Re: What will the Arctic resemble in 2050?
« on: March 20, 2013, 12:46:41 PM »

Newer models accurately simulate the decline in extent and volume.

If a model can accurately simulate the recent declines, then there should be reasonable confidence in its predictive power.



Andrew, accurately simulation of volume is complete non-sense.

Below is a graph of CMIP5-modeled volume trends in September using historical and projected rcp8.5 (=high) forcings.
(it is preliminary ATM, I want do some more checks. Else compare with the similar graph in http://www.cesm.ucar.edu/working_groups/Polar/presentations/2012/stroeve.pdf)

In the 1980's the models differ in volume from about 2 to 40 [1000km3]. So even for the historic part and without comparing with actual volume they cannot be called "accurate" in any reasonable way.
Do you see any other aspect in the graph that can be called an "accurate simulation"?



4052
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 20, 2013, 08:38:01 AM »
Gridded AMSR-E snow thickness data is available from NSIDC upto the failure in Oktober 2011 http://nsidc.org/data/docs/daac/ae_si12_12km_tb_sea_ice_and_snow.gd.html

4053
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 19, 2013, 08:36:34 PM »

Where in the PIOMAS data is the snow information?

The snow.Hyyyy files , see http://psc.apl.washington.edu/zhang/IDAO/data_piomas.html

I agree that regional trends are worth looking into.

4054
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 19, 2013, 04:05:57 PM »
Attached snow thickness according to PIOMAS:

- no thickening to be seen
- May has the thickest snow cover, but also the steepest decline.

4055
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 19, 2013, 10:45:38 AM »
Thanks, this is what i have seen so far in the research.


Well, I haven't searched at all, except for clues in the PIOMAS data. If you have found anything else than the link you posted, please share.

4056
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 18, 2013, 07:26:36 PM »
First attempt is attached: graphing the total volume of snow (it is expressed in volume of water, so needs to be multiplied by some factor).

No time yet for adding a legend yet:

black - monthly values
purple - Jan smoothed
blue - April smooth
green - July smooth
red - Okt smooth

So total snow decreases in all months. That is partly because the ice covered area is declining.
Does it compensate? Wait for more graphs later, no more time today.

[edit: y-scale off factor 1000]

4057
My calculation:

C + O2 -> CO2  + 32.8 MJ/kg-C

atomic number give that 12 kg of C burns using 32 kg of oxygen. So per kg of oxygen we have:
Here is my calculation:

32.8 * 12/32 [MJ/kg-O2]

Electric generating plants come per GW-electric. One GW of generated electric power, at 40% efficieny is 2.5 GW of fuel.

2.5 GW = 2.5 GJ/s = 2500 MJ/s = 2500 * 3600 = 9,000,000 MJ/hr

So we get 9,000,000 / (32.8*12/32) = 731,700 kg-O2 per hour

Since 1 kg oxygen is about 1 cubic meter we need a million cubic meters oxygen (from 5 million m3 air) each hour for each installed GW-e plant.

4058

*** As is often the case, the solution is to avoid the problem. ***

One of the major technological hurdles with CCS is how to capture CO2 from a relatively low concentration stream of power plant exhaust.

Lodger, let me first state that I have some professional experience with combustion processes,  coal firing and electricity generation. I hope for more than 2 cents.

First you solve a problem of capturing a low concentration CO2 ( about 16%) by capturing O2 from air which has concentration only 4% higher!
If the concentration is not such a big deal, there ARE advantages of doing it on the air side. Flue gasses are hot and at the temperature extremely corrosive and poisonous (for catalysors at least). So if it can be shown to be more cheaper on refining the oxygen than that would be the way to go.
Flue gas re-circulation is a well known technique for improvements of the combustion and as you say influencing the temperature of the flue gasses.

Now the feasibility. You need more than half a million cubic metres of pure oxygen per hour per GW installation. The example "industrial" oxygen concentrators in the wiki measure their output in milli litres. I have not heard that the existing industrial nitrogen/oxygen separation plants (that use a liquid air and a fractional distillation) are now redundant.

In the end it comes down what is the process that produces the cheapest useful output.

Now your proposed use of the clean CO2 stream. Using them for concrete hardening and improving glasshouse ventilation efficiency, is NOT reducing CO2 output. Those processes would take CO2 from the air, which is not happening at all. Net result is zero, except more efficient operation which can be achieved by other means. You have to put the CO2 somewhere unused and that is going to add to the cost. Not even mentioning safety.


4059
Arctic sea ice / Re: Effect of snow cover on thickness of arctic ice
« on: March 17, 2013, 07:06:27 PM »
Hmm, the PIOMAS gridded data includes snow thickness.

I will see what I can do, it is not much work but I have very little time in the next few days.

4060
Arctic sea ice / Re: Latest PIOMAS update
« on: March 15, 2013, 10:55:53 AM »
Wipneus- We use more data points because it gives us more statistical significance and keeps us from unconsciously cherrypicking. But the problem with the arctic is that those data points are not equally valid. Each previous year is less likely to describe the arctic as it actually is today.

Hmm. You correctly state mention the advantage of looking at the trends and mention cherrypicking(sic) as a dirty word. Followed by a defending of cherry picked data. All without a single hint of analysis.

Repeat: the physical laws that cause the trend are the same in 1980 and in 2013. The behavior is clearly non-linear, so apparent to the human eyes discontinuities are to be expected.
I have showed a trend drawn with an algorithm that has been found to be much better than deceiving eyes. 

Quote
Also, in your graphic you should exclude winter 2006-07 since that was before the divide.


It seems that your algorithm is: drop points until the result is what you want.  And you are wrong:
cherry picking as you suggest an dropping the 2007 gain, does not change anything at all: 1st of March 2013 data point lies comfortably in the confidence range.

You would have known that if instead of eye'ing the graph you would have tried an analysis.

Quote
Right now I'm just trying to look at the problem from different angles. I'm not in a position to argue authoritatively against your approach, but it seems worth a try to overweight the recent data. At the end of the day it's about what model makes better predictions.

Indeed, I tried to do here for an exponetial fit: https://sites.google.com/site/arctischepinguin/home/piomas/grf/piomas-trnd6-1.png
gomperts model:
https://sites.google.com/site/arctischepinguin/home/piomas/grf/piomas-trnd9-1.png

Too close to call I think.

Quote
Your exponential trend is predicting 2.0.

I'd prefer to say a range of 0 to 4, best value 2. The uncertainty is of course not very satisfying, but that is what the exponential trend method gives.

4061
Permafrost / Re: What is Happening under a Cloud of Methane?
« on: March 13, 2013, 09:59:27 AM »

One can reasonably say that NOx does not form under natural conditions,


NOx is formed by electrical discharges (lightning), you can smell it after a thunderstorm. IIRC the amounts are a significant  natural source of N for plant fertilization.


4062
Arctic background / Re: No Arctic expedition this year...
« on: March 13, 2013, 09:44:48 AM »
Neven, I was thinking about Bernice Notenboom that you blogged about last year. Heard anything about her expedition?

http://neven1.typepad.com/blog/2012/12/the-last-ice-expedition.html

4063
Arctic sea ice / Re: Latest PIOMAS update
« on: March 13, 2013, 09:06:48 AM »

If the discontinuity is that huge, can you accurately map it in one smooth function?


Dave, beware. I was taught a long time ago that physical laws are continuous and the world is mostly continuous as well if studied detailed enough. We already know that volume trends are highly non-linear. Human minds are known (for a fact) not to understand exponential trends and falsly introduce discontinuous, sudden, or unexpected behavior when faced with exponential phenomena.
Just assuming won't do here to make a convincing argument.


-Google for humans do not understand exponential trends
-read Limits to growth, club of Rome


PS, attached is trend focused on 2007-2013. I find it makes your case (IIUC ) look even worse.

4064
Arctic sea ice / Re: Latest PIOMAS update
« on: March 13, 2013, 08:15:33 AM »
Wipneus

I'm planning on stealing a few of your graphics for a presentation I'll be doing in early May - with proper accreditation and your consent of course.


Terry, by all means. I am glad you find the graphs are useful.

Quote
It would be nice if PIOMAS linked to your graphics page as you've managed to tease out so much more from their data than they're able or willing to share.

I am not so sure they like my graphs that much. My graphs are trying to focus on the question of zero ice. I do that because I think their data is begging for it. You can look at all the official PIOMAS graphs without ever realizing that that event might be within the next decade,

Quote
I wonder how PIOMAS is handling the fractures so prevalent this year.

Good question, we don't even know whether the ice in the modeled world of PIOMAS has ice fractures as bad as, or as outstanding as we see on the satellite images now. PIOMAS may have been vindicated somewhat, but only as far as the overall annual cycle and long time trends. The details may differ from reality still.

Attributing the volume increase mostly to the cracks is IMO jumping conclusions. It also ignores the well known physics that colder than normal  temperatures over thinner than normal ice will give larger than normal ice volume growth.

4065
Arctic sea ice / Re: Latest PIOMAS update
« on: March 13, 2013, 07:41:47 AM »
Wipneus,

How did you fit that trend line on the annual gain plot? The data are very scattered.

Cheers, Phil

Hi Phil. It is a Loess (http://en.wikipedia.org/wiki/Local_regression) curve fitted to the data, it is the default smoothing method for the plotting library (ggplot2) that I used in R to produce the graph.

I find the curves are quite useful for trends that are severely non-linear and similar to what an expert human would sketch with graphing paper and pencil.

I realize however now that the graph compares the gain on first of March 2013, with the full gain in other years (realized in April). For an all apples graph, here is the gain on day 60 (attached):
   

4066
Arctic sea ice / Re: Latest PIOMAS update
« on: March 12, 2013, 07:20:42 PM »
For Dave:

Attached is a graph of PIOMAS ice gains (max.volume - min.volume.previous.year).

It shows, as most people here are aware, that volume gains are on the increase. Record gains should be quite normal, and are entirely expected because of  the record low September ice.




4067
Arctic sea ice / Re: Latest PIOMAS update
« on: March 12, 2013, 05:28:20 PM »
So according to PIOMAS , the ice volume and thickness (and therefore area) are at the beginning of March almost the same as in 2012. And still a month to grow even thicker.

4068
Arctic sea ice / Re: Latest PIOMAS update
« on: March 12, 2013, 05:21:11 PM »
From the official graphs:

Thickness:


4069
Arctic sea ice / Latest PIOMAS update (August 2020)
« on: March 12, 2013, 05:07:20 PM »
Hello, PIOMAS has updated:
Latest value: 2013-3-1 19.945
Latest value: 2013-3-31 21.612
Latest value: 2013-4-30 21.273
Latest value: 2013-5-31 19.087
Latest value: 2013-6-30 13.002
Latest value: 2013-7-31 7.104
Latest value: 2013-8-31 5.077
Latest value: 2013-9-30 5.343
Latest value: 2013-10-31 8.218
Latest value: 2013-11-30 11.449
Latest value: 2013-12-31 15.225
Latest value: 2014-1-31 18.938  <- version 2.1 !
Latest value: 2014-2-28 20.86
Latest value: 2014-3-31 22.609
Latest value: 2014-4-30 22.94
Latest value: 2014-5-31 20.288
Latest value: 2014-6-30 14.632
Latest value: 2014-7-31 9.575
Latest value: 2014-8-31 7.22
Latest value: 2014-9-30 7.119 (minimum 2014  on 9-18: 6.810)
Latest value: 2014-10-31 9.701
Latest value: 2014-11-30 13.314
Latest value: 2014-12-31 16.842
Latest value: 2015-1-31 20.229
Latest value: 2015-3-8 22.813
Latest value: 2015-3-31 24.036
Latest value: 2015-4-30 24.066
Latest value: 2015-5-31 21.496
Latest value: 2015-6-30 15.263
Latest value: 2015-7-31 8.604
Latest value: 2015-8-31 5.975
Latest value: 2015-9-15 5.713
Latest value: 2015-9-30 6.032
Latest value: 2015-10-31 8.563
Latest value: 2015-11-30 11.999
Latest value: 2015-12-31 15.652
Latest value: 2016-1-31 18.536
Latest value: 2016-2-29 20.660
Latest value: 2016-4-1 22.337
Latest value: 2016-5-1 22.268
Latest value: 2016-6-1 19.201
Latest value: 2016-7-1 13.177
Latest value: 2016-8-1 7.448
Latest value: 2016-9-1 4.638
Latest value: 2016-10-1 4.869
Latest value: 2016-11-1 6.534
Latest value: 2016-12-1  9.515
Latest value: 2016-12-31 13.078
Latest value: 2017-1-31 16.162
Latest value: 2017-2-28 18.608
Latest value: 2017-3-31 20.398
Latest value: 2017-4-30 20.64
Latest value: 2017-5-31 18.11
Latest value: 2017-6-30 12.164
Latest value: 2017-7-31 6.725
Latest value: 2017-9-15 4.658
Latest value: 2017-11-30 10.871
Latest value: 2017-12-31 14.418
Latest value: 2018-01-31 17.57 (prelim)

I have updated my graphics at Arctische Pinguin https://sites.google.com/site/arctischepinguin/home/piomas/ for the latest data.

Monthly data:

Daily Anomalies:

Daily data with a "prediction" based on exponential trend:

4070
Arctic sea ice / Re: Arctic sea ice free (extent)
« on: March 03, 2013, 03:16:00 PM »
Given the choices I would guest about 2017-2018 frame.

That would be for a low straight average ice period of any 30 days.
The  NSIDC algorithm may compute a mean that is well above a straight average and the minimum may be in August.

4071
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 03, 2013, 03:01:49 PM »
And here is the result (attached):

Still a bit bigger, but the remaining difference can be explained by the uncertainty of the "IceSat domain", I think.

4072
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 03, 2013, 02:54:55 PM »
I tried to reproduce the "PIOMAS on IceSat domain" values from the piomas gridded data.

First the PIOMAS grid with my best guess for the IceSat domain. Area is 7.17 Mm2, Laxon et al. give 7.2 Mm2.


4073
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 02, 2013, 03:02:22 PM »
It is all in the paper:

"The data are restricted to the “ICESat” domain"
"Arctic sea ice volume (km3) for the ICESat domain"

As far as I can see figure 1 is the clearest definition of that domain.

4074
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 02, 2013, 09:36:00 AM »
And attached the plot. Red line is "official" piomas.


4075
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 02, 2013, 09:28:26 AM »
Here is the digitized plot data:
Code: [Select]

[[1]]
          x line_piomas
1  2010.539    8.511989
2  2010.622    5.195339
3  2010.708    4.200344
4  2010.790    5.365653
5  2010.881    7.633525
6  2010.962    9.587660
7  2011.041   11.308732
8  2011.124   12.868454
9  2011.211   14.006872
10 2011.292   14.643311
11 2011.380   14.437141
12 2011.460   12.285800
13 2011.541    7.794876
14 2011.621    4.729215
15 2011.711    3.904534
16 2011.792    4.890565
17 2011.881    7.346680
18 2011.960    9.524912
19 2012.041   11.237021
20 2012.122   12.733996
21 2012.210   13.863450
22 2012.292   14.732950
23 2012.381   14.670202
24 2012.457   11.927243

[[2]]
          x line_cryosat2
1  2010.790      6.844700
2  2010.881      9.892433
3  2010.960     11.165310
4  2011.038     12.483006
5  2011.122     13.962053
6  2011.210     15.692089
7  2011.288     16.274744
8  2011.787      5.249122
9  2011.879      8.996041
10 2011.957     10.788825
11 2012.040     12.249944
12 2012.119     13.648316
13 2012.208     14.723986
14 2012.288     15.907223


(in 1000 km3 of course)

4076
Arctic sea ice / Re: Piomas vs. CryoSat
« on: March 01, 2013, 07:01:10 PM »
And if they are using the "official" piomas figures.
Eg Massonnet et al use a corrected series:

Quote
We also use the Pan-Arctic Ice Ocean Modeling and Assimilation
System (PIOMAS, Schweiger et al., 2011) output for
sea ice volume estimates. This Arctic sea ice reanalysis is
obtained by assimilation of sea ice concentration and sea surface
temperature data into an ocean–sea ice model.We use an
adjusted time series of sea ice volume partly accounting for
the possible thickness biases in the reanalysis (A. Schweiger,
personal communication, 2012)

4077
Arctic sea ice / Re: What will the Arctic resemble in 2050?
« on: February 25, 2013, 08:37:26 AM »

... I await Wipneus's comments on CMIP5.


Unfortunately Quality Control has rejected the calculations. I was not aware that some models have grids with mixed ocean/land cells. Unlike eg. the PIOMAS grid. Difficult to test also.

That means the 300GB or so of data need to be reprocessed. Probably takes most of the coming week.

4078
Arctic sea ice / Re: What will the Arctic resemble in 2050?
« on: February 24, 2013, 08:05:39 AM »

The papers don't give many details on the models or inputs to those models, just discuss their results.


They (Notz et al.), write that CMIP5 scenarios are used.
Start at http://cmip-pcmdi.llnl.gov/cmip5/ probably look at "forcing data" and possibly follow the link to the RCP database.

I will have to say more about the CMIP5 model results soon.

4079
Arctic sea ice / Re: Cryosphere Today 2013 Arctic SIA maximum
« on: February 22, 2013, 06:50:52 PM »
Wipneus,

Now that is a fascinating graph, I've not tried that approach.

Is the blue line and grey region a fit with confidence interval?

It is how I tend to look at the problem: first think volume and after that see how it is spread over the arctic.

The curve is a loess smooth: http://en.wikipedia.org/wiki/Local_regression

The math is maybe a bit complicated, but I find the result very much like what I would draw myself with a pencil and graph paper. Tried a straight line as well, that did not look very convincing.


4080
Arctic sea ice / Re: Cryosphere Today 2013 Arctic SIA maximum
« on: February 22, 2013, 04:59:49 PM »
Predicting the ASI maximum won't be much better than predicting white noise.
Let me try, and see how an attached graph works.
We are probably at or at least very near a minimum volume, so area should be be near the minimum value as well. But we have already passed that.
So my guess is that it will not grow very much, instead of the usual 0.4 Mm2, Go for 0.15.
My prediction: 13.65 Mm2 second week of March.

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