Official "Science News" Thread

[ewmayer]

Big weather news in the US this summer is the relentless heat wave over the east cast and upper midwest. One article I read compared it to the last similar-weather year, 1988. I was living in the upper midwest in '88 (grad. school at UMichigan, Ann Arbor) and remember it well; it was nasty. Basically that year the spring rains stopped in late March, and it did not rain again - at all - until August. Not even the occasional summer thunderstorm - which is one difference to this year, where they just had one mega-storm more damaging than a hurricane to briefly interrupt the heat. But the rest of the pattern seems the same.

In '88, until the rain returned in late summer, we had an unbroken string of days with highs near or over 100F. The ground got so dry that even a significant fraction of quite-old large trees with deep taproots died. The question I have is: Has any particular oceanic/atmospheric phenomenon (along the lines of the ENSO) been implicated in these roughly once-per-generational droughts in that portion of the country? Any weather pattern which persists on those kinds of multi-month scales usually requires an oceanic anomaly (for which such timescales are the natural ones) to drive it.

If anyone can find any links to stories addressing that question, I would be appeciative.

[philmoore]

Originally Posted by ewmayer

The question I have is: Has any particular oceanic/atmospheric phenomenon (along the lines of the ENSO) been implicated in these roughly once-per-generational droughts in that portion of the country? Any weather pattern which persists on those kinds of multi-month scales usually requires an oceanic anomaly (for which such timescales are the natural ones) to drive it.

If anyone can find any links to stories addressing that question, I would be appeciative.

Here's an interesting article from the Guardian quoting a number of climate scientists:
http://www.guardian.co.uk/environmen...global-warming

But none of them address the question of ocean anomalies in the cited quotes. They speak more about the expected increase in probabilities of extreme weather events.

[markr]

Originally Posted by ewmayer

The question I have is: Has any particular oceanic/atmospheric phenomenon (along the lines of the ENSO) been implicated in these roughly once-per-generational droughts in that portion of the country? Any weather pattern which persists on those kinds of multi-month scales usually requires an oceanic anomaly (for which such timescales are the natural ones) to drive it.

If anyone can find any links to stories addressing that question, I would be appeciative.

I came across this article What's behind the record heat?:

The warm summer follows an unusually warm winter, which was the hottest and driest that the western United States has ever seen since records have been kept, said Jeff Weber, a scientist with the University Corporation for Atmospheric Research in Boulder, Colo.

The heat burning up the country right now is due in part to a persistent high pressure system, also called a heat ridge or dome, which parked itself over the mountain west, and has now shifted east into the Midwest and Southeast. The system is unfortunately stuck in place, Weber said, because of a slowdown of the North Atlantic Oscillation, a climate pattern that pulls weather patterns eastward across the country.

This "blocking" of the Atlantic has caused the jet stream, which normally ferries air from west to east across the United States, to buckle and trap heat in the Midwest and Southeast, Weber told OurAmazingPlanet.

That's not unusual in the summer, said National Weather Service meteorologist Greg Carbin. But this pattern of hot air does cover a broader area than usual, and the total amount of hot air is greater, stretching higher up in the atmosphere than normal, he said.

At the moment we are in a La Niña. 1988 was also a La Niña year with quite strong effects here in Australia. La Niña seems to push your (North America) jet stream north and make it weaker and more variable, at least according to this Wikipedia article:

During La Niña, increased precipitation is diverted into the Pacific Northwest due to a more northerly storm track. During La Niña events, the storm track shifts far enough northward to bring wetter than normal winter conditions (in the form of increased snowfall) to the Midwestern states, as well as hot and dry summers.

So put the two together and you could get a very long-lasting weather pattern. Then again, your recent winter was dry & mild. The effect of La Niña on North America is obviously variable, even by weather standards. The graphic in the quoted Wikipedia article has "variable" twice. And the effect varies with the region & season, and a lot depends on how far north the jet stream goes, and on the North Atlantic and Arctic Oscillations. It's a bit simpler down here:

El Niño events are often associated with drier than normal conditions across eastern and northern Australia, while La Niña events are associated with wetter than normal conditions ...

Just now I'm hanging out for this La Niña to end, so it will stop raining all the time!

[Dubslow]

I got cheated out of a decent winter. I'm actually rather annoyed about that.

[ewmayer]

Originally Posted by markr

I came across this article What's behind the record heat?:

At the moment we are in a La Niña. 1988 was also a La Niña year with quite strong effects here in Australia. La Niña seems to push your (North America) jet stream north and make it weaker and more variable, at least according to this Wikipedia article:

So put the two together and you could get a very long-lasting weather pattern. Then again, your recent winter was dry & mild. The effect of La Niña on North America is obviously variable, even by weather standards. The graphic in the quoted Wikipedia article has "variable" twice. And the effect varies with the region & season, and a lot depends on how far north the jet stream goes, and on the North Atlantic and Arctic Oscillations.

Very interesting - thanks for that. The variable effects of the ENSO on the weather in the US Northeast are confirmed by this Wikipedia note, which mentions the combination of El Niño and NAO+ as being responsible for warm NE winters:

Although having a less direct influence than for Western Europe, the NAO is also believed to have an impact on the weather over much of eastern North America. During the winter, when the index is high (NAO+), the Icelandic low draws a stronger south-westerly circulation over the eastern half of the North American continent which prevents Arctic air from plunging southward. In combination with the El Niño, this effect can produce significantly warmer winters over the northeastern United States and southeastern Canada. Conversely, when the NAO index is low (NAO-), the eastern seaboard and southeastern United States can incur winter cold outbreaks more than the norm with associated snowstorms and sub-freezing conditions into Florida, but the phase of this index has a much smaller effect on winter weather patterns elsewhere on the North American continent.

So things seem more complicated in that respect. The hot-NE-summer anomaly, however, does seem to correlate strongly with the combination of La Niña and NAO+; as Wikipedia notes:

The 2010-2011 La Niña was one of the strongest ever observed. The effect on Eastern Australia was devastating.

[ewmayer]

One Big Migration Spawned Most–But Not All–Indigenous Americans

At least 15,000 years ago intrepid Siberians crossed the newly exposed Bering land bridge to arrive in the unpeopled Americas. But was this influx the only ancient wave from East Asia? Researchers have been studying archeological, linguistic and genetic evidence for years in a quest to understand how the first Americans arrived and spread through the continents.

A new large-scale genomic study paints a much clearer picture of these early entrances and distant dispersals that led some people all the way to Tierra del Fuego in a matter of millennia. At least three major waves of migrants from Siberia hit the Americas, but not all of them have had the same reach, according to the findings, which were published online July 11 in Nature

Amusing coda to the summary piece:

Interestingly, the researchers also found traces of Eskimo-Aleut genetic variants in current-day coastal Siberian populations of the Naukan and Chukchi. So perhaps the Americas weren’t quite to everyone’s liking.

So basically, the peopling of the Americas can be attributed to a bunch of guys leading their respective tribal groups toward some destination in NE Asia, getting lost, and in typical guy-fashion, failing to ask directions. But in few groups the wife finally put her foot down, and once it was established that they'd landed on the wrong continent, said "You are turning this car tribe around this instant, buster, or I'm moving back in with my parents."

[rogue]

Originally Posted by ewmayer

So basically, the peopling of the Americas can be attributed to a bunch of guys leading their respective tribal groups toward some destination in NE Asia, getting lost, and in typical guy-fashion, failing to ask directions. But in few groups the wife finally put her foot down, and once it was established that they'd landed on the wrong continent, said "You are turning this car tribe around this instant, buster, or I'm moving back in with my parents."

"I knew I should have taken that left turn at Albequerque." - Bugs Bunny

[davieddy]

Originally Posted by rogue

"I knew I should have taken that left turn at Albequerque." - Bugs Bunny

I used to live on the east side of Norwich.
Some would-be holidaymakers from Leicester asked me how to get to Skegness.

Apparently they had taken the wrong direction in Kings Lynn.

Non-Brits may need to consult a map to appreciate why I found this amusing!

D

PS my advice was "go to Yarmouth then turn left".

[rogue]

A few links:

Running on Quicksand

Lightest manmade material

When is a metal not a metal?

[Dubslow]

Two more men with HIV now virus-free. Is this a cure?

[Batalov]

Uncorking the muse: alcohol intoxication facilitates creative problem solving.

Jarosz AF, Colflesh GJ, Wiley J.
Department of Psychology, University of Illinois at Chicago, 1007 W. Harrison St. MC 285, Chicago, IL 60647, USA.
Consciousness and Cognition. 2012 Mar; 21(1): 487-93.

"That alcohol provides a benefit to creative processes has long been assumed by popular culture, but to date has not been tested. The current experiment tested the effects of moderate alcohol intoxication on a common creative problem solving task, the Remote Associates Test (RAT). Individuals were brought to a blood alcohol content of approximately .075, and, after reaching peak intoxication, completed a battery of RAT items. Intoxicated individuals solved more RAT items, in less time, and were more likely to perceive their solutions as the result of a sudden insight. Results are interpreted from an attentional control perspective."