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wayne

I like the last daily average graph displaying a maxima shift linked with the effect of the sun, the thinner the ice the earlier the maxima. This matches exactly what I have observed. For 2013 at 75 North 95 W the under-ice is melting for close to 12 hours daily. Will post the first 12 hour underside net melting, it could have been yesterday, but I await several days of repetition.

I also remade my calculations about the North Pole cam horizon drop which appears to be very large. I scratched my original calculation and await more pictures. The drop appears beyond all previous observations, this requires more evidence , but may be indeed linked with the recent ridging, suggesting a lot of thin ice about.

Wipneus


PIOMAS update:
Latest value: 2013-4-30 21.273

I have updated my graphics at ArctischePinguin for the latest data.

Monthly DataMonthly data
Daily AnomaliesDaily Anomalies
Daily data Daily data
Daily data with a "prediction" based on exponential trend Daily data with a

Somebody asked, so I added a few more error bars. The uncertainty (95 % confidence) is calculated as the result of the fitting uncertainty and the the uncertainty of the data.

Wipneus

I have updated my graphics, announcement in the spam box :-(

[Released. Thanks, Wipneus. N.]

Wipneus
I have updated my graphics, announcement in the spam box :-(

[Released. Thanks, Wipneus. N.]

It seems that now even posts without any links can be considered as s p a m. Or is using that word considered suspect?

Neven

There's just no logic to it, Wipneus. It's getting extremely annoying.

Bob Wallace

It's a bad time to consider a big site change, but Discus does not have this problem.

At the minimum there should be a "whitelist"/"trusted user" list function. That would be a small software tweak.

Jai Mitchell

Wipneus, A-team,

your graph with trendlines of monthly data show that the summer thaw months are breaking from the trend and the rate of melt is increasing at a faster rate. Does anybody know of a modeled reason for an increasing rate of melt for MJJ versus OND. Is this an indication of warmer SST moving into the arctic?

wayne

NOAA CAM 1 from the North Pole represents a less fractured sea ice surface, the horizon appears to go down, but its difficult to measure. However the snow over sea ice there looks "baked" a pre puddling look, well in advance to what is seen at 75 N. Because unlike over the CAA the sun is always up. http://eh2r.blogspot.ca/

Chris Reynolds

Neven,

Beware of using PICT as a measure of thickness, this time of year it's about 1 to 3% off PIOMAS, by late summer it can be 30% off due to concentration being low.

Neven

Definitely, Chris. But I'm not interested in the thickness per se, but rather in the comparison to other years. It's good though that the PSC have an average thickness graph of their own.

crandles

>"(although, contrary to the other graphs, it doesn't seem to be updated all the way to the end of the month):"

If you look at Jan then it is clear the marker is at the middle of the month (and it is the same with their volume graph). So end of April is the midpoint between April and May markers and both graphs therefore appear to run to April 30.

SATire

Jai Mitchell,

"Does anybody know of a modeled reason for an increasing rate of melt for MJJ versus OND"

You know, that the climate modells failed to predict the sea ice area - they predict todays status for 2030-2050... The exponential is just one of the working trend lines (similar to linear or Gompertz). But the exponential in that graph is also the solution of a very simple/stupid rate equation for albedo-feedback (loss rate proportional to ice-free area). If the exponential trendline is working in the months with sun light it could be a weak indication, that the albedo-feedback is actually governing the sea ice loss in summer.

Timothy Chase

"Does anybody know of a modeled reason for an increasing rate of melt for MJJ versus OND"

If I could try my hand at this...

Climate models are based on physics, and while they can't include all of the different processes that are involved, the interactions or unlimited resolution. They can be expected to at least get at some of the core processes at sufficient resolution to see some of what is going on.

In terms of winter, it doesn't really matter how much ice melts during the melting season, so long as the temperature drops below freezing in the Arctic basins, the area that was lost will be iced over. And the Arctic is surrounded by land that has essentially prevented a larger area from freezing in past decades, so until the globe warms enough during the winters that a significant part of the Arctic remains above freezing, you shouldn't see much of a trend there.

But with the summers the temperature goes above freezing, and the longer the period of time and the higher the temperature, the more the melt. With greater melt you will see more ice albedo feedback, not simply with sea ice being replaced with darker ocean that absorbs more sunlight, but with partially melted ice being darker than ice that has never melted.

Old ice has had the salt and other impurities melted out of it, and has been compacted with each melting season it survived, increasing the albedo and raising the melting temperature. But less of it survives the melt season nowadays.

Young ice will tend to have more salt in it, more green algae, and will tend to be thinner, permitting dark ocean to show through. Ice that is weak will more easily be broken up, and broken ice will permit larger waves to form and travel through it, breaking up the ice even more. And with larger waves there should be more mixing with the deeper, warmer, saltier ocean water below.

I wouldn't expect all the models to capture each of the processes. But many will capture a number of them, perhaps all of them, and probably a fair number of others that I haven't even thought of. Anyway, my two cents.

wayne

Learning fast due to new optical method. Photochemical created ice crystals are shortening the underside melting time in the CAA at 75 N. A bit more about this on top: http://eh2r.blogspot.ca/

Meanwhile back in Scotland, great refraction effect to study is seen in Fraserburgh live: http://www.aberdeenshire.gov.uk/webcams/fraserburgh.asp

a neat comparison is made http://eh2r.blogspot.ca/2013/04/data-gathered-from-optical-refraction.html

Stevemosher.wordpress.com

Timothy

"Climate models are based on physics, and while they can't include all of the different processes that are involved, the interactions or unlimited resolution. They can be expected to at least get at some of the core processes at sufficient resolution to see some of what is going on."

One of the things that climate models do poorly is absolute temperature. I'm currently working with NARCCAP data and the problem of future heatwaves ( http://www.narccap.ucar.edu/) and one difficulty is that absolute values of things like temperature are off by physically significant amounts.

For the arctic, I would suspect that the cold bias exhibited in many models may be a problem.. dunno.

See below


"We usually focus on temperature anomalies,
rather than the absolute temperature that the
models produce, and for many purposes this is sufficient.
Figure 1 instead shows the absolute temperature evolution
from 1850 till present in realizations of the coupled
climate models obtained from the Coupled Model
Intercomparison Project phase 3 (CMIP3) [Meehl et al.,
2007] and phase 5 (CMIP5) [Taylor et al., 2012] multimodel
datasets available to us at the time of writing,
along with two temperature records reconstructed from
observations [Brohan et al., 2006]. There is considerable
coherence between the model realizations and the observations;
models are generally able to reproduce the
observed 20th century warming of about 0.7 K, and
details such as the years of cooling following the volcanic
eruptions, e.g., Krakatau (1883) and Pinatubo (1991), are
found in both the observed record and most of the model
realizations.
[6] Yet, the span between the coldest and the warmest
model is almost 3 K, distributed equally far above and
below the best observational estimates, while the majority
of models are cold-biased. Although the inter-model
span is only one percent relative to absolute zero, that
argument fails to be reassuring. Relative to the 20th
century warming the span is a factor four larger, while it
is about the same as our best estimate of the climate
response to a doubling of CO2, and about half the
difference between the last glacial maximum and present.
To parameterized processes that are non-linearly
dependent on the absolute temperature it is a prerequisite
that they be exposed to realistic temperatures for
them to act as intended. Prime examples are processes
involving phase transitions of water: Evaporation and
precipitation depend non-linearly on temperature
through the Clausius-Clapeyron relation, while snow,
sea-ice, tundra and glacier melt are critical to freezing
temperatures in certain regions. The models in CMIP3
were frequently criticized for not being able to capture
the timing of the observed rapid Arctic sea-ice decline
[e.g., Stroeve et al., 2007]. While unlikely the only
reason, provided that sea ice melt occurs at a specific
absolute temperature, this model ensemble behavior
seems not too surprising"

Timothy Chase

Steve, could be.

I seem to remember that resolution is also an issue in the Arctic. Temporal resolution was one of the issues that Gavin dealt with regarding the Arctic atmosphere -- longer intervals were sufficient at lower altitudes, but shorter intervals are required to more accurately model the Arctic, and I believe it is Serreze who argues that regional modelling does better with the Arctic involving changes to ocean circulation.

In any case, it helps to give references when you quote from papers. Open access, pp. 2-3:

Mauritsen, Thorsten, et al. "Tuning the climate of a global model." Journal of Advances in Modeling Earth Systems 4.3 (2012).
http://onlinelibrary.wiley.com/doi/10.1029/2012MS000154/pdf

Wipneus
For the arctic, I would suspect that the cold bias exhibited in many models may be a problem.. dunno.

You could start first looking how well the volume of ice is modeled. As seen in:

volume of CMIP5 models vary from something like 2.5 too much to 6 (!) times too little in 1980.
So the first question is, are the models that have too much (little) sea ice volume the same that have absolute temps too low (high) ?

My CMIP5 page in development : https://sites.google.com/site/arctischepinguin/home/cmip5

wayne

Wipneus, what I would need is live time access to a model capable
of estimating whether the ice is melting or freezing (accretion). This way we can say how good the model is by live time verifications.
Sort of like weather models but for ice. The lack of access to what they actually are producing is not doing them any favors.

Wipneus

Wayne,

CMIP5 models outputs lots of variables as output. See for instance http://www.hpsc.csiro.au/users/ofa001/Cryosphere.doc

But they do not do "live time access" as I understand it. Instead of the real "weather" they are driven by an atmospheric model (or the part of the model that does the atmosphere).

PIOMAS (not part of CMPI5) is driven by an reanalysis (NCEP/NCAR) so that may have what you need. Data is only by month and updated mostly one every year. It can be found here:
http://psc.apl.washington.edu/zhang/IDAO/data_piomas.html

Chris Reynolds

Jai Mitchell,

The following is a plot made from PIOMAS gridded data.
http://farm9.staticflickr.com/8115/8684706810_9bb4de3e11_o.png
It has been made by taking each grid box's effective thickness in April (bottom, X, axis) and plotting against that the percentage of grid boxes of each April thickness band (5cm bands) that are open water (<5cm) by September.

You'll note that the percentage of open water formation increases massively as April thickness drops below 2m. 2m thick is the typical thermodynamic growth in one freeze season, by which I mean that open water in September will result in ice roughly 2m thick by April, within the Arctic Ocean.

In 2010 there was a volume loss event that caused a massive thinning of the ice pack after 2010. More here:
http://dosbat.blogspot.co.uk/2013/03/what-caused-volume-loss-in-2010-part-2.html
This has brought more of the pack into the region of around and below 2m thick in April. Which means that there are more grid boxes for which April to September production of open water is now falling into the region of maximum change of % open water shown in the first link of this reply.

As for the mechanism for the spring volume loss anomaly. It is not clear to me what this is.

However the increase in anomaly in Oct/Nov/Dec is more clear - that is because more ice is being produced at that time than in the climatological period due to 'growth/thickness feedback'. Thinner ice or open water produces new ice more quickly than the thicker ice which existed in the past.

Chris Reynolds

Neven,

Comment in the spam folder again.

Stevemosher.wordpress.com

@ Timothy, sorry about the lack of linkage, in a rush.

@ Wipneus, great work, looking fwd to more..

back to lurking at one of my favorite places.

Jai Mitchell

Thank you all!!! so my summary appears to be that:

1. below 2M thick icepack the albedo is much lower due to the presence of salt and plankton and (other contaminants) which allows a more rapid melting during the spring period. Since we have recently had a tipping point in spring thaw (2007 and 2010) the likelihood of a regular annual volume September minimum of <1000 KM^3 is now very likely.

2. The fall freeze period has a more rapid buildup due to increased moisture content and longwave heat loss. So it doesn't appear to be losing ice volume as rapidly as JJA.

I hope you all know you are invaluable!

wayne

Many thanks Wipneus you are right, these are nice but not practical.
what I need is :

Surface_downwelling_longwave_flux
Surface_upwelling_longwave_flux
Surface_downwelling_shortwave_flux
Surface_upwelling_shorwave_flux
Surface_upward_sensible_heat
Surface_upward_latent_heat

at any given point of the sea ice at any time of day. So I can compare if the model conforms with reality.

At day time with sunlight the upwelling long wave flux is very strong and causes all near surface inversions to disappear. But it is more complex, aerosols, ice crystals, ice thickness, clouds, winds and snow cover play havoc with the end result constantly. For an ice model to be properly checked it must either calculate the presence of a boundary layer at the ice surface to air interface. The result is readily visible, the calculation truly complex, and requires the weather model to be coupled with it. A monthly result is unacceptable. I can sense we can resolve the reason why sea ice models fail very quickly, only if we can see them give results like GRIB or another model. That is why there are radiometers near the North Pole. I think that they are working on the problem. But again, we can help. Only If the products are more accessible.

wayne

75 N 95 W sea ice underside is melting about 10 hours a day, and freezing for about 12 for 1 week, the melting was slowed by photochemical ice crystal showers diminishing the hot rays from the rising sun. 2013 melt times exceed 2012 during the same time period. This despite being in the coldest place in the Northern Hemisphere. The larger change is not measurable by temperature , the lapse rates are strongly adiabatic, aiding the ice crystal haze. Is likely going to be the same story further North. I am waiting for the first optical capture ever of a more than 12 hours underside melt. Will publish as soon as it happens. Ice crystals prove to be more complex than I thought. http://eh2r.blogspot.ca/

R. Gates

Here's something very much worth watching. There's a large and intense high pressure area in the Arctic stratosphere that has been migrating down toward the troposphere over the past few weeks:

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_HGT_ANOM_AMJ_NH_2013.gif

It remains to be seen if it will reach into the lower troposphere, but IF it should, it would hit about the time that the June melt and maximum solar insolation hits. Would make for a very intense period of melt across a broad area of the Arctic.

John Christensen

@R. Gates,

Thank you, and yes, it would be very concerning if a high pressure places itself centrally over the Arctic during the peak weeks around mid-summer.

A broader question:

I follow the mean Arctic temperature above 80 degrees N (http://ocean.dmi.dk/arctic/meant80n.uk.php) as well as other nice features on DMI and noticed the current mean temperature is 4-5 degrees Kelvin/Celcius lower than normal. That would intuitively be good, but as I compare to last year, where temperatures during spring/early summer also were relatively low, then I wonder if the low temperature is a signal of bottom melt; that the transition from ice to water is releasing the cold, so that air temperatures seem low, but this is due to melting from below.

Would fit well with the number of cracks across central Arctic as well..

Anyone with better grasp of things, please comment.

R. Gates

John,

I expect the 80N DMI to turn around pretty quickly to higher temps in the next few days. The higher pressure anomaly is sill working its way down from the stratosphere and I think may have some effect in the next 10 to 20 days on surface pressure. You can see that here, where it's been descending a few km a day:


http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_HGT_ANOM_AMJ_NH_2013.gif

ECMWF shows the first wave of high pressure and higher temps could be setting up over the Beaufort beginning around May 28th. That area could intensify and expand if the current stratospheric anomaly descends with larger force and persistence.

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