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Messages - Random_Weather

Pages: [1] 2 3
1
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: February 06, 2020, 07:48:05 AM »
Interesting to have a near real time volume estimate.  Thanks for doing that.

What is the uncertainty range indicated on graph 95% CI (2.5% to 97.5% of estimate distribution)?

Is the current value calculated with same sources and methods as the 2011-2018 average?

How the Volume estimate using this method compare to PIOMAS volume for same dates?

Its min/max value + unc of the instruments, in a more formal way:

max_min+-Unc = Max_Min(Volume) for the Date +- the Volume of the instrumental Uncertainy (which is often 0.1m in Thickness)

to the rest:

Its calculated all the same way, as you note at the first side of the thread here, there is a figure of compare PIOMAS, Cyrosat2 and this product

greets


2
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: February 05, 2020, 09:50:32 PM »
Hi Jim,

Yes i also done a new script which allows to estimate volume direct to sea ice concentration, thickness and the area of the grids, results looks like this



the only thing i think about is to add is again the nrt data, but analysis is just 2 weeks behind so for that, i think it must not

3
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 29, 2020, 09:21:34 AM »
Since i account for instrumental uncertainy, its not for sure, but when you look at the "Min", its lower in 2019/2020 then as every year 2011_2018 (dotted black)

4
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 29, 2020, 06:23:33 AM »
Update + change from Exel to "R" + change from NSIDC to AMSR2



now include the most recent volume of the "lines"

5
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 21, 2020, 06:10:50 PM »
Update on Volume


6
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 19, 2020, 09:29:12 PM »
And here why i use r-script, today written:





7
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 16, 2020, 08:26:42 PM »
Thanks for the thread. Volume is more important than area or extant.

Well, except for aldebo and the whole Arctic amplification thing.

Thats also a way to simply view, ice is a good but not perfect isolator, if ice gets thin enough, energy can be advected to the water below the ice surface, also young and fresh ice in winter times allows atmosphere to interact with the ocean below the ice. Thats why T2m-Anomaly often over fresh sea ice is very large also if the weather pattern would imply cold.

So sea ice thickness is not just about thickness ist also about Arctic amplification

8
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 14, 2020, 05:17:31 PM »
@ Glen

Melt-Saison has variance and if we look back over time, its not done yet, in the data i have, a good chance for all volume is gone after melt saison, is when spring volume is below 15km^3.

So we now at 13.37km^3 and usually there will grow arround 4.5 km^3, if so, there have to be the strongest melt saison ever to get this volume down

9
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 07:38:06 PM »
Hope that makes it clearer:

10
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 05:57:29 PM »
Here the Histogramms:

09.01.2019

09.01.2020


In 2020, SIT above 3m not exists

11
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 03:12:49 PM »
But is not important here, because SIT is a direct meassurement of every grid over detected sea ice

12
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 12:37:15 PM »
As note in literature, thickness is not only a result of temperature but also from compaction, even more above (i hope i remember correct) 2m, the ice itself gets so isolated from Temperatur at surface that 10-20K more or less is no more effects thickning .

And last summer kills a lot of the thickest sea ice

13
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 11:43:14 AM »
In other words:

mean thickness at this date:

2019: 1.137332m
2020: 1.000787899m

while extent is nearly the same

15
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 12, 2020, 08:22:15 AM »
Update until 9.01

16
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 06, 2020, 04:55:21 PM »
its seem pretty normal, that sea ice volume in PIOMAS becomes greater then in the merged product of SMOS+Cyrosat2, its likely that PIOMAS ends near to the dotted line "Max+Unc"

greets

17
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 05, 2020, 09:30:55 AM »
With PIOMAS

18
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 03, 2020, 02:30:57 PM »
Update on SIV (to 30.12.2019)

19
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: January 03, 2020, 11:50:58 AM »
First of all, happy new year @ all

Nxt Part, SMOS at Melt-Saison:

First some notes:

1) SIT below 5cm is cut out, because there sometimes errors in the mapping at these low SIT
2) Its from 15. Apr to 1.09 Sep 2011-2019
3) SIT= Sea Ice Thickness
4) SIE = Sea Ice Extent

Some claims:
As often told, SMOS is not a physical use of SIT in the melt saison because of melt ponds cause interference which indicate the ice is very low in thickness, on the other hand, we can use this to claim, if SMOS SIT is very low at the begin of melt saison, its build up very much melt power, in other words, it preconditioning the outcome to september SIE.

Thats what i think i found in my analysis.. anyway some figures:

2019,2012 vs mean 2011-2018


Scattern Plot SMOS SIT(1.06 bis 15.07) vs. SIT (NSIDC September)


One more thing: If correlation is used for SMOS SIT after 15.07 the correlation gets near to 0 which also would imply the claims above

20
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 27, 2019, 06:05:44 PM »
Also to note, as thicker the ice gets, as greater becomes the uncertainy of
the measurement. Here Scatterplot for the Mean of 2011-2018:
SIT= Sea Ice Thickness
SITU=Sea Ice Thickness-Uncertainy



21
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 27, 2019, 05:59:14 PM »
Just in short, if taken account for instrumental uncertainy, it would look like this: (up to 24. Dez)



Uncertainy becomes that large, that PIOMAS will all time time within the bands (Min/Max+Unc), i think thats more fair in compare with other products.

For those who may interest in, the .nc-Data also have the variable: "analysis_sea_ice_thickness_unc"

Explantion for the Figure: (SIV)
Mean_2011-18 = mean(thickness)*mean(extent)
Max+Unc= (Max(thickness)+uncertainy)*Max(Extent)
Min+Unc= (Min (thickness)+uncertainy)*Min(Extent)
2019(...)



22
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 25, 2019, 02:01:31 AM »
Update to 21.12


@gandul
Nxt weeks i am most time at holiday, would make nxt up-to-date comparison in early january

23
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 19, 2019, 04:59:50 PM »
Cery interesting, RW.  Conceptually, the depth of snow will increase as the Arctic warms, but the winter ice area (~= extent) is decreasing, so a stasis is possible. 

I was wondering somewhere if increased winter ice mobility would cause more frequent lead openings and thus more opportunity for snow getting blown into (onto?) the water.  But maybe this possibility is an order (or two) of magnitude below the big picture.

In the short period, (2011-2018) Trends

SISM:

Okt; -0.122Gt/y
Nov: -0.393Gt/y
Dez: -0.260Gt/y
Jan:  -0.452Gt/y
Feb:  -0.633Gt/y
Mar:  -0.870Gt/y
Apr:  -1.477Gt/y


Mean Snow Depth (MSD)

Okt; +0.07cm/y
Nov: +0.01cm/y
Dez: +0.11cm/y
Jan:  +0.06cm/y
Feb:  +0.04cm/y
Mar:  +0.11cm/y
Apr:  +0.09cm/y


Its a to short period for making any significant claim, but as the data would imply, loose of sea ice(could also be the leads or the drift of ice with very much snow) overcompensate increase snowfall that its turn out an negativ Trend of SISM

24
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 19, 2019, 02:37:47 PM »
Its also possible to make Sea Ice Snow Mass (SISM) for the arctic: ftp://ftpsrv2.awi.de/sea_ice/product/cryosat2/v2p2/nh/l3c_grid/monthly/

- Use Snow Thickness
- Use Snow Density
- Use NSIDC Extent

You get:


In other words, arround 190-200 Gigatonnes (Gt) Snow Mass every year on arctic sea ice, before melt saison beginns. This is quite stabile, havent though its that low variance

25
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 18, 2019, 08:29:07 PM »
Oh, I think this is all excellent! Though I'm sometimes accused of being easily impressed...

Thanks much for the explanation of your metric. Many of us are yearning for the best way to understand the condition of Arctic sea ice, while watching it get blown hither and yon. (I've unexpectedly absorbed a whole new feeling for ice dynamics from the Mosaic reports and data.) Efforts just like yours are the reason I can't break my ASIF habit.

Thx for your kind words, by the topic of MOSAiC, i use this here for track position
ftp://ftpsrv2.awi.de/sea_ice/mosaic/jpg/large/

greets

26
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 18, 2019, 08:00:25 PM »
And perhaps the Scattern Plots for Cyrosat 2 and PIOMAS for 2011 to 2019(april) mon_mean

PIOMAS vs. NRT SIV



Cyrosat2 vs. NRT SIV


No surprise, Correlation must better against Cyrosat2 because its related to it in main fraction, besides the infill from SMOS. Also to note, on higher SIV, products beginn to have larger variances

27
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 18, 2019, 07:47:12 PM »
It will be interesting to see over time how this product and PIOMAS compare over a whole year. Especially summer, when thin ice makes life so much more difficult.

The Problem is, from 15th April to 21 Okt there will no data be available, therefore its just only winter product.

Meanwhile in compare to PIOMAS (used the same way as decribed before) from 21th Okt to 1. Dez 2019:

28
Arctic sea ice / Re: Near Real Time Sea Ice Volume
« on: December 18, 2019, 06:02:43 PM »
SIV to 15 Dez:


PS: Update will occour every week or so

29
Arctic sea ice / Near Real Time Sea Ice Volume
« on: December 18, 2019, 06:01:09 PM »
Hi,

I build up an Near Real Time Sea Ice Volume (NRT SIV) product based on merged data from SMOS and Cyrosat2. To make it very simple, i decide to use mean sea ice thickness(SIT) and extent(SIE) data from NSIDC, beside this, it would also be possible by grid by grid methode, but since in winter, sea ice concentration (SIC) has not much variance over the domain, its seem unlikely that much differences would occur.

First things first, some Explantion:

SIV:  Daily
SIT:  5 five-day trailing average
SIE:  5 five-day trailing average

Its because of the merged SIT is just in a 5 five-day trailing average format accessible, therefor its also used for SIE and the final product SIV. What does this mean?

SIV(5 Nov): SIT(mean(1-5Nov))*SIE(mean(1-5Nov))


Some Plots:


SIV 2011-2018


NRT SIV vs. Cyrosat2 and PIOMAS (Okt to May)



Open Points for Future:
- Uncertainy-Bads from merged SMOS-Cyrosat2
- Testing other SIE like Uni-Bremen
- Melt-Saison-Model

Data-Source:
ftp://ftpsrv2.awi.de/sea_ice/product/cryosat2_smos/v202/nh/ ->analysis_sea_ice_thickness CS2SMOS merged sea_ice_thicknes
https://nsidc.org/arcticseaicenews/sea-ice-tools/ -> ea_Ice_Index_Daily_Extent_G02135_v3.0.xlsx -> 5 five-day trailing average

30
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: December 18, 2019, 02:52:27 PM »
Thank you, Random_Weather. That looks quite appropriate for this thread, and very nice, imho.

I don't know what they're paying the folks maintaining this thread, but it's not enough!

The thing is, volume is much better then extent for the state of arctic sea ice, an NRT SIV (Sea Ice Volume) product based on observation is in my opinion a much more better way to isolate winter effects on it.

Remember the autumn 2016 with the very very low extent and very high temperature anomalies? Its not very much effects SIV (i think because of compaction due to drift from atlantic side)

Here in compare to 2012-2013 Refreeze Saision

31
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: December 17, 2019, 04:36:18 PM »
For those who may interest i, i made up an NRT Sea Ice Volume Product(Based on SMOS and Cyrosat2), which will be Update here: (not every day but i think i will update every week or so)

https://twitter.com/Christi89994998/status/1206153596737339392

To 14 Dez:

32
Arctic sea ice / Re: 2019 vs 2012
« on: August 11, 2019, 06:51:58 AM »
Neven,

Thats very easy, you just need to download: https://www.giss.nasa.gov/tools/panoply/

I wonder that most people here dont know about?

33
Arctic sea ice / Re: 2019 vs 2012
« on: August 10, 2019, 01:29:48 PM »
For some Folks not uninteresting


Data: ftp://ftp.remss.com/sst/daily/mw_ir/v05.0/netcdf/ (need for registry)
Red: 2019 warmer
Blue: 2019 cooler


https://seaice.uni-bremen.de/data/amsr2/asi_daygrid_swath/n6250/netcdf/

Red: 2019 more SIC
Blue: 2019 less SIC

34
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: July 03, 2019, 04:06:16 PM »
"2012 is the front runner as regards area again."

Its all of source you use: http://data.meereisportal.de/maps/latest/area_n_en.png Area here 6.34 Mio km^2 and for now the lowest on record

35
Arctic sea ice / Re: SMOS
« on: July 19, 2018, 06:01:44 AM »

36
Arctic sea ice / Re: The 2018 melting season
« on: July 18, 2018, 06:22:32 PM »
Can anyone explain me how it is possibble that the past 3 winters were the warmest "ever" in the Arctic and yet summers are not much to talk about. Where does the extra heat from winter go? Why does it not show up in big extent losses later on?

We always looking at anomaly of temperature, strong positive anomlies during winter-times dosent mean, that there is "heat", its always cold, just only less cool then years before. To be clear, the "heat" from winter is physical much cooler then the coldest summer which has been observed.

Mean, if Winter dissapears, anomalies also dissapears and in Summer, because of sea ice which thermodynamics mean, as long as ice is here, it take the most power for melting ice and not increase temperature. Therefore, as long as ice is there, big anomalies like in Winter are simply not possible.

During Melt-Saison, there is a lot of variation on Melt-Power which is build up, it also is able to compensate some loos of thinning ice in Winter, therefore the minimum is most likely the result of summer temperature, especially June.

Also look here: https://forum.arctic-sea-ice.net/index.php/topic,2327.msg162958.html#msg162958

37
Arctic sea ice / Re: September Predictions Challenge
« on: July 11, 2018, 04:25:23 PM »
My own is: 4.24 +-0.33 Mio km^2

Will also published in the SIPN July Outlook, for details go here: https://www.docdroid.net/9FEP0oD/model.docx

For Performance:

38
Arctic sea ice / Re: The 2018 melting season
« on: May 14, 2018, 07:27:39 PM »
jdallen,

Correct, GFS is strongly warm biased with time, since years i watch this, therefore i think its an issue with snow cover..

also see: http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_arctic/verification/ANOM2m_bias_past07_arctic.html

to the +168h forecast, there is a massive warm bias to the past 7 days

Also evident over the full northern hemisphere: http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_mollw/verification/ANOM2m_bias_past07_mollw.html

39
Arctic sea ice / Re: Home brew AMSR2 extent & area calculation
« on: September 03, 2017, 07:53:30 PM »
"Increase of extent and even more so area. End of the melt season, minimum reached? That would be surprisingly early, bumps like these have sometimes reversed (2015)."

I dont think so, but if, it would not so much surprisingly... relativ cool august, early strong cool air production and a sector with much relativ low concentrated sea ice and therefore a good chance of early overfreeze. We saw this last year, where to the end, much ice going below 15% criteria and just a few weeks laster, strong increase of ice above 15% criteria.

Therefore, i would not be surprised if this was the End of melt season

40
Arctic sea ice / Re: The 2017 melting season
« on: June 11, 2017, 08:38:59 AM »
On JAXA-Sea-Ice-Thickness:

If some is wondering about it, it should be to understand that Thickness is meassured by the ice emissivity (something arround 50-100 GHz), while during Winter its working good, in melt saison this could lead to spurios estimates of ice Thickness.

41
Arctic sea ice / Re: The 2017 melting season
« on: June 03, 2017, 03:23:35 PM »
@ seaicesailor

Y, melt-ponding is very weak in the ocean, only archipelago and hudson-bay show strong sign of melt-ponding. For me, it seem like a more normal to a weak start in melt saison

42
Arctic sea ice / Re: The 2017 melting season
« on: May 31, 2017, 03:16:14 PM »
@ Iceman (Insolation between 80-90N)


https://climexp.knmi.nl/data/ifresco6_ssi_-179.5-179.5E_80-90N_n__yr.txt

Fresco SSI is using a cloud fraction algorithm

43
Arctic sea ice / Re: The 2017 melting season
« on: May 22, 2017, 06:02:38 PM »
seaicesailor,

Yes, the best webpage to compare this is here: http://www.karstenhaustein.com/climate.php

Since end of April, GFS has a increasing Warm-Bias on NH

for arctic only you can look here:
http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_arctic/verification/ANOM2m_bias_past07_arctic.html

Its not so new, saw this also years before, its likly an issue with snow cover, because GFS tend to a far to strong melt in spring-time

44
Arctic sea ice / Re: The 2017 melting season
« on: May 20, 2017, 11:17:22 AM »
be cause,

correct at all, GFS is performing very bad in Forecast, there is a huge warm bias

Look here: http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_arctic/verification/ANOM2m_bias_past07_arctic.html


45
Arctic sea ice / Re: IJIS
« on: May 15, 2017, 04:17:18 PM »
@ Jim

Y, as said in another thread, its all about summer saison, you can start in May with record low ice and dont get a record low in september, on the other hand, if ice undergo in summer record low, its likly it will does in september. In easy words, its a cascading effect in summer, if melt is weak during early summer (June) it would trigger enough feedback that prevent a new record, or its strong it will likly force a new minimum.

This weakness of melt in last June, is likly the cause of not setting a new record in 2016

46
Arctic sea ice / Re: Latest PIOMAS update (May)
« on: May 02, 2017, 01:26:57 PM »

That's interesting, and also somewhat surprising, as I expected this month to show a big uptick (given low volume and low temps).


Hi Neven,

I think its because of the high temperature anomalies arround pacific side and the transport of ice to the atlantic where its fighting against the warm north atlantic current also transport due framstrait.

And temperature never was so low, just 0.2K less warm then 2016
http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_monthly/ANOM2m_GFS_monthly_arctic.php?date=Apr%A02016&file=ANOM2m_CFSR_GFS_1604_monthly_arctic.png
http://www.karstenhaustein.com/reanalysis/gfs0p5/ANOM2m_monthly/ANOM2m_GFS_monthly_arctic.php?date=Apr%A02017&file=ANOM2m_CFSR_GFS_1704_monthly_arctic.png

47
Arctic sea ice / Re: IJIS
« on: May 02, 2017, 11:20:19 AM »
I suspect some rapid melt in the next 7 days around greenland

temps well over 0c forecast

Same as i, because not only of temp, also on thickness: http://data.seaiceportal.de/maps/smos/n/2017/thumbs_800/thick_n_20170430.png

48
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: May 02, 2017, 09:30:00 AM »
Incidentally, RW, do you have a post somewhere where you explain your model ?
Or did you make an entry for Arcus SIPN where we can read about it ?

Rob, yes, if arcus is calling for june report, then my model will start and explained on there webside. This should happen arround the End of May. Before, i dont want to share exactly what i did.

49
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: May 01, 2017, 09:39:20 AM »


RW, thanks !
Do you have a similar graph (as you did for JJA) for June PIOMAS volume (regressed against September SIE) ? And what you find as the SD for the residuals of that (June) model ?
That would tell something about the predictive value of (June) PIOMAS volume numbers.

Hi,

No, to make its clear, its not volume, its T2m and SST on a arctic domain which is put together to a model which is very good after May. It dont need Volume, because its respresent volume in a indirect way also for summer melt conditions. So as you ask here some skills of Model (to predict SIE September)


Month : Sigma1

June = 0.41 Mio km^2
July = 0.40 Mio km^2
August = 0.38 Mio km^2

For Summer-Saison
JJA  = 0.32 Mio km^2


50
Arctic sea ice / Re: Latest PIOMAS update (April)
« on: April 30, 2017, 09:18:37 PM »
PS: As said before, all things are nearly useless before summer comes, the summer makes the things up

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