Wednesday, March 26, 2014

AABW in the news!

It only took 25 years, but my thesis topic is now becoming newsworthy!  Gluttons for punishment can see at least the abstract at A model of the formation of high-salinity shelf water on polar continental shelves.  Which is aimed at one of the important ingredients for AABW (Antarctic Bottom Water).

I've been reluctant to blog about the topic because it is, after all, my baby and I'm sorely tempted to post at excruciating length and detail.  (Not that there aren't other people who have studied the topic before or since, but I'm one of the people who has.)

I'll take this note as opportunity to get in to some detail about the weirdness that is sea water, and come to the climate change, carbon dioxide burial, and heat burial, aspects later.  The story of AABW turns on some odd facts about how sea water behaves in Antarctic conditions.  Not least, it can go below freezing.

Monday, March 24, 2014

Harry Bulkeley: A few questions about global warming -- Answered

An opinion writer (a retired judge) asked a few questions in his Galesburg, IL local paper, and I'll provide some answers here.  As always, I encourage you to read the original.

The good judge, like the usually informative Mr. Krauthammer, starts off on a very wrong foot, with bad philosophy of science.  There are many facts in science -- the earth is round, the sun is hot, there is a greenhouse effect, and CO2 is a greenhouse gas.  All can be questioned -- but not in the trivial way that Bulkeley and Krauthammer seem to think.  'I question it' is trivial, and pointless.  If you have a _scientific_ question about these things, or any other, it is because, and only because, you have scientific evidence that the 'fact' is false.

Climate change, as even commenters in agreement with Bulkeley note, is indeed a fact.  Climate changes, that's a fact.  One of the tasks of science is to try to understand the hows and whys of that fact.

Let's see about the questions:
1) Average temperature has indeed gone up the past 15 years.  This is a question, apparently, because the author didn't bother to look at the data. One can experiment with time periods and trends at NOAA/NCDC.  
It's worth paying attention to the fact that climate trends are defined on 30 year periods, not 15.  Some discussion of why this is the case is at

Wednesday, March 5, 2014

Science Fair Participants

First: Congratulations to Elliott Rebello, winning his category in the Eleanor Roosevelt HS Science Fair.  (The reason I single him out -- he's my intern.  Be sure, though: the work he presented was his.  And it was his presentation and understanding that earned him his place.  Yay Elliott!)

Having judged another year's science fair at ERHS, I'll share some thoughts for participants.  I'm a little emboldened that maybe I know something since Elliott did well.  On the other hand, maybe he did well in spite of me.  Use your own judgement on what ideas to make use of, and how to make use of them.

One note: I never did very well in science fairs when I was growing up.  You don't have to do well in science fairs to do well in science, even more true than you don't have to be good at math to do well in science.  One failing in most of my projects: I was setting about learning what was already known, rather than striking out my own path.  This is an excellent way to learn more, but not to get science fair points.

My base suggestion for any age: try to learn more about the universe, know what you did and why you did it.  Maybe there are points in it, maybe not.  But you'll definitely learn something, which is always good.

For science fairs, the major categories on the official judge's score sheet are: 'Scientific Thought', 'Creative Ability', 'Thoroughness/Clarity', and 'Exhibit Presentation'.  They have some connection to usual professional proposal or paper review criteria (except, mostly, for exhibit presentation).
But we all, and it's interesting that it's all of us given that we come from different backgrounds, even judges in my rather small niche, think differently than this.  We start more like journalists:
  • What did you do?
  • Why did you do it?
  • Why did you do it this way?
  • What did you learn?
  • How would you do it differently?  (given what you've learned)

Tuesday, March 4, 2014

Hurricane Control?

Reader Bayesian Bouffant raised the question of whether we might be able to take some of the strength out of hurricanes, if not to really control them -- by way of an article Massive offshore turbine arrays would help us harness hurricanes.  The article is more positive about chances for weather modification than I, but let's take a look at some details and issues.

By way of background, hurricanes are heat engines.  The heat source is partly warm oceans, but mostly the latent heat released when water vapor condenses in the atmosphere.  The source of that water vapor is, again, warm oceans -- but by way of evaporating water vapor from the ocean surface in to the atmosphere.  When the water condenses, it releases heat, which drives the circulation, and makes for clouds.  The rising air draws more air in, again along the ocean surface. 

Over the years, there have been many suggestions for trying to weaken hurricanes.  One of the least reasonable is to throw a nuclear bomb at the hurricane.  Somehow this is supposed to 'disrupt' the hurricane.  But, hurricanes are heat engines, and nuclear bombs supply heat.  They also don't really have much energy compared to a hurricane!  In one day, a hurricane releases about 52*10^18 Joules (see Christopher Landsea's estimation of the wattage of a hurricane).  The Hiroshima bomb released about 67*10^12 Joules.  Roundly speaking, 1 day of a hurricane is a million Hiroshima bombs.

Since frontal assault is pretty well doomed by the fact that hurricanes are vastly, overwhelmingly, more energetic than anything humans have to wield, any attempt to control, or affect in any meaningful way, has relied on more indirect means.

Thursday, February 13, 2014

Science Fair Judges

I'll write about and to science fair judges before a note to the students.  A joke I made today got its due chuckle, but there's a real point to it.  I observed of judges that "We're very scary people."

Now, we know ourselves, and scientists in general are not scary people at all.  Even more so, if anything, those of us who do science fair judging.  We tend to be parents with school age kids ourselves, or at least not too long since we were (and, in my case, I'm still an uncle to kids this age).  And to like talking with kids and have a certain degree of understanding of (in today's case) 14-18 year olds. 

On the other hand, I can recall ages back, when I was a 26 year old finishing his PhD and presenting at an international scientific meeting.  Only about 200 people in the room (on the other hand: 200 people in the room!).  And I was 26 and nearly done with a PhD, not a 14-18 year old in perhaps my first talk with a scientist.  But I was seriously nervous, before, during, and after.  Most of that was unnecessary, as, again, scientists aren't actually a very scary bunch.  (It did work out in my accidental favor, more in a moment.) 

It was a great relief to survive the talk (nobody threw anything!  er, ok, that didn't happen to anyone, and I'd never seen it happen before.  But ... I was nervous).  And it was thrilling when, unforced, one of the 'Big Name in Field' people present said they'd liked my presentation.

I try to pass this along (not the big name in field aspect, which I'm not, but at least a good word somewhere).  And try to de-scarify for the students I talk to about their work.  We're still pretty scary to the students.  But I enjoyed my chats with students, and hope they came away with a bit more understanding of doing science.

The 'more in a moment':  The later postscript on my presentation was about my nerves.  Back then, when I was nervous, I spoke slower.  Opposite of most people, but it worked in my favor.  The thing was, at an international meeting, many people (in this case, about 2/3rds) are not native English speakers.  A speed that a nervous native is capable of racing through can be all but impossible for a non-native to follow.  Since I slowed down, I was more understandable to the group.  Several folks thanked me for my consideration.  They didn't know it was terror :-)

Tuesday, February 11, 2014

PIOMAS ice volume anomaly q

Q: I've got a question that you may be able to answer with your sea ice hat on.

Why is it that the minimum volume anomaly of ice appears in mid summer and not in September when the minimum volume happens? See piomas.
(From Alastair)

A: I'm hard-pressed to tell what season the anomaly extremes are occurring from this graph, but can say that your reading isn't surprising to me.  At the seasonal minimum of ice volume, you're at the minimum -- so it is relatively difficult to get even lower.  Late winter, towards the maximum doesn't have that problem -- since it's maximum, there's lots of room to go lower.  But the Arctic is cold in winter, so it's going to pile up a lot of additional mass (from the prior minimum) pretty consistently.  The place/time that there's the most room for decreasing the ice volume is a time of year when the ice volume hasn't already declined a lot, but it is melting rapidly -- early- to mid- summer.

As you also see from the figure, the main trend is the year-round decline.  For your question, we're looking at the timing of largest excursions below the line. 

The converse question, for largest excursions above the trend, is that I'd expect those in late fall - early winter, during the freeze-up season.  Then, there isn't much volume, and it's freezing fast.  A couple weeks earlier start to freeze-up makes a comparatively large difference.

Monday, February 10, 2014

Evaluating 2013 sea ice outlook estimates

Very late wrap on my 2013 sea ice season guesses, but, as I was thinking in early August, the straight statistical one busted pretty badly.  The observed (NSIDC) September Average sea ice extent was 5.35 million km^2.  The guesses were:

The original outlooks (end of May) were:
3.9 million km^2 -- Grumbine, Wu, Wang statistical
4.1 million km^2 -- Wu, Grumbine, Wang model-based
4.4 million km^2 -- Wang, Grumbine, Wu model-based statistical
The end-June Wu et al. estimate was 4.7 million km^2.
The end-July Wu et al. estimate is 4.57 million km^2.
As I suggested then, I'm going to get back in to the statistical approach to try to fix it up.  While we don't expect excellent estimates from it, if it's using a sound basis, it shouldn't be wrong by this much.  I have some ideas on how to do it. 

Still, better estimates than Stephen Goddard's end of August (the 26th) prediction -- Doubling of Arctic Ice in 2013.  Doubling September 2012 would have meant 7.26 million km^2.  (I was just touring web sites, and saw this article, which reminded me that I hadn't posted the evaluation of my forecasts.)

Wednesday, January 29, 2014

Science Tweeters to follow?

Yesterday I mentioned a few science tweeters.  Today I'll ask you for your favorites on science.  Any science.