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Messages - uniquorn

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Arctic sea ice / Re: The 2020 melting season
« on: Today at 12:27:24 PM »
ascat day60-89 comparison (or closest available day), 2010-2020. First year ice distinguishable by location and darkness. click to run
Maybe Niall will measure the movement :)

Alcohol shouldn't be a problem. We make a lot of plum and fig wine but only one gallon of grape. Though it will be weaker if the sugar runs out. Anything that's undrinkable gets turned into eau de vie. If that's undrinkable it makes a good handwash. No shortage of vinegar either, some if it cider.
We'll go with chestnuts rather than acorns.

Arctic sea ice / Re: The 2020 melting season
« on: March 30, 2020, 06:04:18 PM »
historical perspective
It's difficult to compress a long time series into a small enough file size so this is 6.5MB for ascat fram export 2010-2020. The present episode doesn't look like the worst thing that has happened (yet).
I can remove this after 47hrs if it causes problems to low bandwidth users.

Also large, but not auto downloaded is worldview, terra modis, closest non cloudy day to mar29, 2000-2020. Medium contrast has been applied to highlight leads.
Some years look worse, 2010 looks bad in a different way. click to run

uni-hamburg amsr2uhh, caa and nth greenland, 2012-2018 can be found here

Arctic sea ice / Re: MOSAiC news
« on: March 30, 2020, 01:47:17 PM »
S1B from mar28 and mar30. PS getting sheared
85.3776N 13.1756 @ 08:40

Arctic sea ice / Re: MOSAiC news
« on: March 30, 2020, 01:47:43 AM »
Overview of Pbuoys (not P88) click to run, twice for full res - ctrtffr

Developers Corner / Re: Test space
« on: March 30, 2020, 01:41:38 AM »
Someone is speeding
temp post of nearly all Pbuoys - removed

Arctic sea ice / Re: MOSAiC news
« on: March 29, 2020, 09:19:25 PM »
There's a newish Rbuoy if anyone wants to analyse albedo

Arctic sea ice / Re: The 2020 melting season
« on: March 29, 2020, 08:42:49 PM »
nothing out of the ordinary
One thing that is different, or that I haven't seen before, is the large leads that have developed since feb15 making their way around north greenland so early in the season. With >80km/h winds forecast on apr1 we are likely to see them open up more.
Kaleschke SIC leads, oct1-mar29

Arctic sea ice / Re: MOSAiC news
« on: March 29, 2020, 08:01:33 PM »
Yes, 6 more Pbuoys (I think I can count 7, or maybe they are a different batch). Should give us a good idea of drift into the fram. Not much snow in that image.

Today's S1B showing how fractured the area further north east is. PS could be a lot worse off.

ok. I added thickness*100 to the charts and got this
and I think I'm mixing Th numbers with thickness

Thinking about those rough charts, it would be easier to compare them if they all started on the same date. I think the shallow gradient was during the warm spell in October, some of the Tbuoy's data don't start till late oct/nov. Of course, if the ice is thin, it thickens quicker.

Rough charts based on the data above. Some different curves.
Note that the heat120 method appears to shift the air-snow and snow-ice thermistor no.s upwards, possibly due to heat rising. I haven't corrected for this. Even so, that doesn't explain 0 or negative starting position unless data was sent before (or during) buoy installation. hey ho, it's an estimate.

Estimated thermistor numbers based on last entry in heat120 files (chart attached, cffr)
buoy   Th(snow)   Th(ice)
T56   24   35
T58   18   34
T62   40   51
T63   18   32
T64   24   47
T65   12   35
T66   42   49
T68   34   46
T70   32   42
T72   28   36

T69   25   35

Yes, except 40 only applies to T62. Need to identify the Therm number for the others.

Arctic sea ice / Re: MOSAiC news
« on: March 28, 2020, 09:13:30 PM »
Latest S1B (cffr) PS is white dot roughly centre, on the rift

Arctic sea ice / Re: The 2020 melting season
« on: March 28, 2020, 09:09:30 PM »
Looking at the Wipneus graph
This is maybe confirmed by the Greenland Sea sea ice area graph<>
Volume is similar, area is higher = thickness is lower.

Arctic sea ice / Re: MOSAiC news
« on: March 28, 2020, 12:02:47 PM »
Drift speed up to 1.32km/h overnight

Arctic sea ice / Re: The 2020 melting season
« on: March 27, 2020, 11:37:51 AM »
Following up on amsr2 ice concentration in the Beaufort. The present conditions perhaps alter or amplify surface reflections that are not normally visible since the sensor is picking up features that move with the ice, probably ridges. (Temporarily providing us with SIC ridges as opposed to SIC leads) Heavy contrast has been applied to the right hand image.

The second animation shows a more persistent low concentration area in the Laptev. We will find out soon enough if that is real or also an artifact of 'conditions'

unihamburg-amsr2uhh, beaufort, mar14-26 and ess/laptev, mar10-26

I get it. It's the mean temp rise over 120s. In which case it should still be valid as temps rise.

That's not so bad but could be misleading without dates. edit: many lat/lon's are bad on the temp_proc files, it's better to use the _ts file for location.
If those thicknesses compare closely enough with the basic method I'd be happy to use them though as mentioned previously I'm not too keen on smoothing.

added heat file ani for reference

Arctic sea ice / Re: The 2020 melting season
« on: March 26, 2020, 12:44:59 PM »
I suspect that it is due to heavy cloud cover and/or other atmospheric conditions at this time of year. There was a similar discussion last year (and some before that)
Here is uni-hamburg mar31 2019 for comparison. It disappeared a few days later.
It is also visible on Aluminium's 2019 link above.

I should have included
import matplotlib.pyplot as plt

Mean_t is the mean temperature at that measurement point (each per 10-single measurements) for each thermistor.
That's what I assumed, but why are the values from 0-5?
mean difference?

Arctic sea ice / Re: The 2020 melting season
« on: March 26, 2020, 11:03:20 AM »
There is evidence that the heat is there in the Beaufort from whoi itp114 but at 30m depth, with little visible mixing, it is unlikely to have a large impact at the moment. sep20-mar26
Salinity is steadily rising at 5m depth but that could be down to brine release from ice formation. 
click for full resolution. Day numbers at bottom of charts

got these on the way to making the animation. Using some of your py code with this below               
        #try to save plot
        plt.savefig("meantst5.png", dpi=400)
        #plt.savefig("stdtst5.png", dpi=400)

At least 2 stdev stand out in what I think is the snow layer. I'm not sure what mean_t is yet but it looks the most useful.
click for full res

Check here for original macidR gganimate code and these nice 3d buoy presentations.

Greenland and Arctic Circle / Re: The Nares Strait thread
« on: March 25, 2020, 06:10:19 PM »
Looking back, a few small sections of younger ice have broken off since the 16th.

I was thinking of turning the 126 t64heat stdev images into an animation, just to get a feel for the movement.
Overlay was done in gimp. Drag both images in, measure the width of the charts in pixels, scale then set white to transparent.

Arctic sea ice / Re: MOSAiC news
« on: March 24, 2020, 11:19:43 PM »
Anybody got a good link for up to date reasonably accurate PolarStern location.
mmtest files here have PS location to 2dp but are updated infrequently.

or there are nearby buoys

Those fluxes are in the atmosphere. I overlayed T64 thermistor1 onto daily temperature. Maybe our algo should detect air/snow first. There seems to be a defined line there, then snow/ice, then ice/water. Possibly only using mean heat temp change.

Looking only at T64 where the chart shows 3 clear drops in estimated thickness. The temperature ani doesn't show any bottom melt events. There are, however, some higher air temperatures that flatten the curve that may occur at roughly the same time as the 3drops.
Not exactly a bug but perhaps an error in the method.
Some thermistors are recording persistently higher temperatures. Perhaps there was a problem during calibration
Was using Spyder but jupyter charts are good

Still need to see a time series of the stdev(10rows) charts to see it they are messing about during temperature rises

Arctic sea ice / Re: The 2020 melting season
« on: March 24, 2020, 12:05:12 PM »
An overview of sea ice movement as seen by ascat, jan1-mar23
The amsr2 low concentration area in/around the Beaufort correlates quite well with the darker area on ascat but may also be related to the recent heavy cloud cover.

If it's not too much trouble, please include T1 in the final csv. It will make it easier to run temp vs thickness analysis

I hoped that would be the case. Still shovelling here.

Arctic sea ice / Re: MOSAiC news
« on: March 23, 2020, 12:00:16 PM »
radar update. The ice to the north west looking stronger during that episode.

Arctic sea ice / Re: MOSAiC news
« on: March 22, 2020, 09:56:49 PM »
It looks like the Polarstern has shifted position or the radar configuration has changed
One lead shuts and another one opens.

Added a comparison of today's S1B with oct6. ctr
Akademik Federov still in shot

Arctic sea ice / Re: The 2020 melting season
« on: March 22, 2020, 08:43:02 PM »
That makes it a long time with very little Beaufort gyre movement
osi-saf, sep21-mar19

whoi itp112 drift track (deployed sep2019)

Overnight thoughts: As temperatures rise to close to zero I think we will be looking at a very flat curve across the thermistor chain. More experienced minds than ours will have grappled with the problem of identifying the 'ice-air-water interfaces' and offered this heat method as a solution.
Perhaps stdev and delta will be more reliable when run on these files       2013
5. Heated operation mode
Theory of operation
The novel feature of this new IMB buoy is the development of chains that can be operated in what can be described as either a ‘‘hot-wire anemometer’’ mode or a needle-probe thermal conductivity mode. Hot-wire anemometry is a standard technique in experimental fluid dynamics and has been widely described (e.g., Perry 1982;La Barbara and Vogel 1976). Essentially a temperature-sensing element in a moving fluid is heated to above ambient temperature, and the amount of heat required to maintain a constant sensor temperature is measured. The amount of heat required depends on both the thermal characteristics of the surrounding fluid and its flow velocity. In principle, the output of the Maxim DS28EA00sensor device can be refined for the estimation of both these quantities, thus allowing determination of the position of the ice–air–water interfaces and quantification of flow speeds. The sensitivity of the present design is not yet capable of the quantification of flow speeds

There is also a  HEAT030 file for each buoy (edit the url). Maybe one is good for ice-water and one for ice-snow etc.
We've just had 4T of manure delivered so no coding today. Running an animation instead. Tbuoy locations, mar22, click twice for full res

Arctic sea ice / Re: The 2020 melting season
« on: March 22, 2020, 10:05:15 AM »
A large area of the Chukchi Sea looking lightly frozen yesterday.
click for full resolution

Arctic sea ice / Re: The 2020 melting season
« on: March 21, 2020, 08:35:25 AM »
Kaleschke SIC leads, Fram funnel, mar10-21.
Worldview Terra Modis , Svalbard-FJL gap, mar10-20
click to run

I think the U shape is good. If you have time I'd like to see how it moves with time. I might be able to chart it in R if not.

I experimented with changing the number of rows from 10
5 rows was worse
20 rows removed the large drops but the algo is struggling to detect the ice/snow boundary so ice goes up when snow goes down.
at 50 rows other problems crept in.

So far it is good for detecting snow+ice thickness
I'll play with this line in the meantime
#select the region with large stdev snow

If we had a large training dataset
rofl. This is probably the biggest it's ever gonna get.

adding the Tice/water, Tsnow/ice numbers etc to the csv might help debugging, maybe I can do that?!?

T69 had a trauma of some kind as noted upthread. The other drops don't show up on reply#9 animation showing bottom thickening so are probably related to the method used to detect the nearest snow/ice thermistor.
I think the 'warm snap' around feb20 may be the cause.
10 rows perhaps too short - it might be easy to edit such well documented code.... :)

Here are the buoys charted from SimonF92 data. It's unlikely the snow layer is so variable. Probably due to the method and changing temperature. Highly likely that it is adequate for this thread, especially as the snow will be gone soon enough.
T69 may still have some value so I left it in

ESS-4S, 72.77N 161.30 is visible again.

Comparison of the new code ( with the basic method. Pretty close agreement on ice thickness. We have no way of verifying snow depth but looking at other buoys may show us if we are on the right track

added yesterday's S1 of the area
nearest coords, roughly middle of the crop

Arctic sea ice / Re: The 2020 melting season
« on: March 19, 2020, 12:40:53 AM »
uni-hamburg amsr2-uhh, bering, mar10-17
added wipneus regional extent, bering, mar17

T56 method comparison
eyeballing the numbers Therm-snow/ice=30 for the spreadsheet method
Spreadsheet method is less complicated, std dev+ is more mathematically justifiable
Is the difference down to snow depth?

Nag to the 17: This is probably a once in a decade opportunity to use the mosaic project to gather almost unprecedented near real time arctic data. Perhaps you are content to sit back and watch a model. Maybe a view from a satellite. Maybe just wait for someone else to do it. But why? There are over 70 active buoys in the arctic today(Mar18). Why aren't we analysing them?? If we are. Why aren't we sharing??

Is this an ice or an ice+snow thickness estimate? I'm still working my way through the coding.
Do you get the same thickness chart as above with the wild swings at the end? If so, what could cause them? I ran the temperature charts to see if they could explain it. Perhaps it is the temperature gradient flattening out. If so that may be a problem as temperatures rise.
edit:latest fomo may help identifying snow layer

testing temperature chart with SimonF92 generated provisional thickness estimate
temporary post as it is large

Developers Corner / Re: Test space
« on: March 18, 2020, 02:44:43 PM »
testing from here   ctr  day68 and 76
Needs a little work to present as a time series. Python here we come I suppose
courtesy of SimonF92

Arctic sea ice / Re: MOSAiC news
« on: March 18, 2020, 12:23:25 PM »
The lead stays open

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: March 17, 2020, 10:31:34 PM »
must take a look a the beaufort again soon. Here is whoi itp114

Arctic sea ice / Re: Arctic Ocean salinity, temperature and waves
« on: March 17, 2020, 09:14:08 PM »
update on the low concentration ice north of greenland using Kaleschke SIC leads. ctr

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