http://climateprogress.org/2009/01/27/nsidc-arctic-sea-ice-drops-below-2007-levels/#comment-44543

Hmm! “The day by day meanderings of Arctic sea ice extent are not overly meaningful yet, but I think they are worth reporting because it bugs the deniers to see any evidence whatsoever that the world is not undergoing global cooling”

I was somewhat amused and certainly not “bugged” to see that the NSIDC image has continued to update itself through to May.

You’re fashionably late for the party but we’ve beaten this dead horse, buried it and then dug it up many, many times over.

In particular, the preference for a linear trend of cyclic data is ripe for abuse by the presenter, causes arguments over the base period, etc.

IMHO, this area of investigation, sea ice area/extent/thickness/age is one of the fat butt of climate research; certain to devolve into trivial controversy.

This is state-of-the-art statistics pre-1650 (before Fermat and Pascal). Absurd that on such a weak foundation the newspapers warn about the end of the world.

Since the bell-curve is called the “normal” distribution, it is not very far fetched to call values in the interval [mean plus/minus standard deviation] “normal”.
Example: An IQ between 85 and 115 is “normal”.

“So the fact that this May 1st is the same more or less as the average of all other May firsts (which is what is shown on the May 1st date of the average curve) is very useful. It says that we are absolutely normal for arctic ice.”

This is the problem with ignoring standard statistical tests. “Normal” is a vague and somewhat loaded word, misleading when used to mean “the average of period showing a strong trend down.” Esp so when looking at a short-term series of such noisy data.

Which is why I suggested alternative and more commonly used methods to show the trend. The NSIDC gives one such: Average Monthly Sea Ice Extent. The graph of March numbers is here:
http://nsidc.org/images/arcticseaicenews/20090406_Figure3.png

It will be interesting to see the April graph. I suspect it will be similar, suggest that the trend might be reversing — but that it is too early to say for sure.

There are some immense patches of low-concentration ice right in the middle of the Arctic basin, which I never observed before at this time of the year. Even the multi-year ice that drifted in the Barents sea is beginning to melt now. Given the wind pattern we had, we might well be heading for a new record.

The use of colors in the linked image is “unusual.” Black appears in more than one place on the spectrum. I suspect the black areas near the pole are the 95% band, not one of the lower ones.

There are some immense patches of low-concentration ice right in the middle of the Arctic basin, which I never observed before at this time of the year. Even the multi-year ice that drifted in the Barents sea is beginning to melt now. Given the wind pattern we had, we might well be heading for a new record.

http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm

This kind of zig-zagging happens a lot. Don’t let your emotions fibrillate with it.

Every time it gets too close it mysteriously bends downward a little so that way it will take even longer to reach the average line…I smell something, and it smells like bias.

Not long ago, the line was altered upwards. If you watch it every day for a few months you will be convinced (as I have) that it’s just real data, subject to a simple smoothing algorithm. The previous couple of days were adjusted downwards retroactively, based on the information learned from the latest day. You can quibble that they should just publish a jagged graph with no smoothing but even JAXA’s AMSR-E uses a running 2 day average and it’s a lot more jagged.

If Dr. Meier wants to tell us his smoothing algorithm, I’d be interested but it’s not important. (I’ll bet it has the word “exponential” in it.)

Remember, right now the other arctic sea ice graphs show less recovery than NSIDC’s. If you’re looking for something that smells, go sniff them.

Every time it gets too close it mysteriously bends downward a little so that way it will take even longer to reach the average line…I smell something, and it smells like bias.

Pamela Gray (10:33:43) : Loopiness allows mixing and extreme weather pattern variation. Hot here, cold there.

I find it helpful to think of it as a spherical lava lamp. Hot tropical air (powered by a 30 year accumulation of ocean heat) makes blobs headed to the cold pole. Colder than typical polar air makes blobs of cold headed south. A big ‘heat engine’ driven by the differential temperature redistributing the heat from the topical oceans to the polar zones for radiation away.

Don’t know if it’s the correct physics, but I find it a helpful image… ;-)”

Near enough but may I suggest the following:

1) Warming of air by the oceans pushes energy into the air, expanding the equatorial air masses, and the extra energy in the air is then accelerated to space.

2) Cooling of air by the oceans shrinks the equatorial air masses so that larger and more frequent surges of colder drier polar air move towards the equator across larger areas of ocean and pull energy from the oceans to try and balance the energy flow to space with energy from the oceans.

3) The air can push extra energy to space and pull it from the oceans.

4) The air cannot pull energy from space or push it into the oceans.

That says it all really.

Yup. Your example would be a “price vs Simple Moving Average” (temp vs moving average of temp) and is my most basic indicator and where I start from on reaching understanding. My second “go to indicator” is the MACD the Moving Average Convergence Divergence that takes two moving averages of different length and compares them (crossovers indicate turning points most of the time). The stochastic responds faster in a trendless market so is good for fast trading flat stocks (would tell you weather better) while the MACD is slower but works best with trending markets (would tell you longer term changes happening in a truly warming or cooling climate and would call inflections in that trend fairly well).

I do think that many of the stock tools could be used to good effect in weather and climate predicting. I explain the ones I use here:

http://chiefio.wordpress.com/2009/03/15/indicators/

skeptic (11:01:56) : Let me see if I’m understanding this correctly.. right now, the sea ice has been well below average for about 95% of the graph, and at normal (giving it the benefit of the doubt) about 5% of the time. [...]

A reasonable person would look at all the data and likely conclude

A reasonable person would conclude that if you are at normal you are normal and we are at normal. Or would you conclude that a fever dropping to 98.6 F means you are still at 105?

By contrast, a cherry picker would sieze on the one measurement that supports his viewpoint and write a whole blog post about it

Nah. A cherry picker would calculate the rate of increase from the abnormally low level back to normal and pronounce: “Record Rate Of Sea Ice Creation!!! More ICE Formed (per day) than in YEARS!!!”

If the datum doesn’t support you, perhaps the integral (or derivative) will… that’s the kind of thing the AGW crowd does all the time…