Category: Uncategorized

Uncategorized 1 Apr 2017

The electric sands of Titan

via Tallbloke’s Talkshop
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View from Titan [artist’s impression]

‘The grains that cover Saturn’s [largest] moon act like clingy packing peanuts.’ An obvious question might be: where is Titan’s electrical charge coming from?

Experiments led by researchers at the Georgia Institute of Technology suggest the particles that cover the surface of Saturn’s largest moon, Titan, are “electrically charged.”

When the wind blows hard enough (approximately 15 mph), Titan’s non-silicate granules get kicked up and start to hop in a motion referred to as saltation. As they collide, they become frictionally charged, like a balloon rubbing against your hair, and clump together in a way not observed for sand dune grains on Earth — they become resistant to further motion.

They maintain that charge for days or months at a time and attach to other hydrocarbon substances, much like packing peanuts used in shipping boxes here on Earth. The findings have just been published in the journal Nature Geoscience.

“If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties,” said Josef Dufek, the Georgia Tech professor who co-led the study. “Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts.”

The electrification findings may help explain an odd phenomenon. Prevailing winds on Titan blow from east to west across the moon’s surface, but sandy dunes nearly 300 feet tall seem to form in the opposite direction.

“These electrostatic forces increase frictional thresholds,” said Josh Méndez Harper, a Georgia Tech geophysics and electrical engineering doctoral student who is the paper’s lead author. “This makes the grains so sticky and cohesive that only heavy winds can move them. The prevailing winds aren’t strong enough to shape the dunes.”

To test particle flow under Titan-like conditions, the researchers built a small experiment in a modified pressure vessel in their Georgia Tech lab. They inserted grains of naphthalene and biphenyl — two toxic, carbon and hydrogen bearing compounds believed to exist on Titan’s surface — into a small cylinder. Then they rotated the tube for 20 minutes in a dry, pure nitrogen environment (Titan’s atmosphere is composed of 98 percent nitrogen).

Afterwards, they measured the electric properties of each grain as it tumbled out of the tube. “All of the particles charged well, and about 2 to 5 percent didn’t come out of the tumbler,” said Méndez Harper. “They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck.”

Earth sand does pick up electrical charge when it’s moved, but the charges are smaller and dissipate quickly. That’s one reason why you need water to keep sand together when building a sand castle. Not so with Titan. “These non-silicate, granular materials can hold their electrostatic charges for days, weeks or months at a time under low-gravity conditions,” said George McDonald, a graduate student in the School of Earth and Atmospheric Sciences who also co-authored the paper.

Visually, Titan is the object in the solar system most like Earth. Data gathered from multiple flybys by Cassini since 2005 have revealed large liquid lakes at the poles, as well as mountains, rivers and potentially volcanoes. However, instead of water-filled oceans and seas, they’re composed of methane and ethane and are replenished by precipitation from hydrocarbon-filled clouds.

Titan’s surface pressure is a bit higher than our planet — standing on the moon would feel similar to standing 15 feet underwater here on Earth.

“Titan’s extreme physical environment requires scientists to think differently about what we’ve learned of Earth’s granular dynamics,” said Dufek. “Landforms are influenced by forces that aren’t intuitive to us because those forces aren’t so important on Earth. Titan is a strange, electrostatically sticky world.”

Researchers from the Jet Propulsion Lab, University of Tennessee-Knoxville and Cornell University also co-authored the paper, which is titled “Electrification of Sand on Titan and its Influence on Sediment Transport.”

Source: The Electric Sands of Titan | Georgia Tech

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April 1, 2017 at 05:21AM

Uncategorized 1 Apr 2017

Arctic Ice Marches On

via Science Matters
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MASIE ice extents reported March 8 through 31, 2017.

This time of year the heart of the Arctic is frozen solid, and the only changes occur in the marginal seas. Above shows the Atlantic basins, especially Kara, Barents, Greenland Sea and Baffin Bay. All of them seesawed during the month, with some fall off at the end, especially noticeable in Baffin Bay.

Meanwhile on the Pacific side, Bering fluctuated, while Okhotsk lost extent steadily toward month end.

Context

The monthly ice extent average for March provides indication of any year’s annual maximum, prior to melting down to the September annual minimum. Sometimes a lower March extent yields a lower September extent, but not always: 2012 had both the highest maximum and lowest minimum in the last 11 years. That was the year of the Great Arctic Cyclone, and an outlier in the record.

Looking at the 11-year averages in the MASIE data set, the pattern in round numbers is:
Maximum: 15.0 M km2
Minimum: 4.8 M km2
Loss: 10.2 M km2
Loss: 68.0 % of maximum

Over this period, the ice extent loss most years varies from 66 to 70% of the maximum. Obviously, all the factors affecting ice extents are in play: (Water, Wind and Weather) with the September outcome uncertain, but likely to be in the range observed.

March 2017 in Comparison

As has been reported, ice formation this year has been sluggish compared to other years. The graph below shows March 2017 compared with the 11 year average, and with 2006 and 2016, as well as SII (Sea Ice Index).

This March started below average, held steady until the third week, recovered some before dropping off at the end. SII showed lower extents all month but drew close at the end. 2006 dropped off more rapidly than 2017, while 2016 ended near average.

The Table below shows Day 90 extents across the Arctic Seas compared to averages and 2006, the lowest recent year.

Region	2017090	Day 090 Average	2017-Ave.	2006090	2017-2006
(0) Northern_Hemisphere	14228992	14791162	-562170	13913402	315590
(1) Beaufort_Sea	1070445	1070018	427	1068683	1762
(2) Chukchi_Sea	966006	965297	709	959091	6915
(3) East_Siberian_Sea	1086168	1085794	374	1084627	1541
(4) Laptev_Sea	897845	896573	1272	897773	71
(5) Kara_Sea	831189	924617	-93428	922164	-90974
(6) Barents_Sea	525362	656247	-130885	623912	-98550
(7) Greenland_Sea	705581	661500	44081	604935	100645
(8) Baffin_Bay_Gulf_of_St._Lawrence	1467334	1426694	40641	1026934	440401
(9) Canadian_Archipelago	853214	852652	562	851691	1523
(10) Hudson_Bay	1260903	1251383	9521	1240389	20514
(11) Central_Arctic	3247995	3235035	12960	3241074	6921
(12) Bering_Sea	702504	847340	-144836	662863	39640
(13) Baltic_Sea	29767	75051	-45284	129348	-99580
(14) Sea_of_Okhotsk	575084	830273	-255189	588167	-13083
(15) Yellow_Sea	0	99	-99	1067	-1067
(16) Cook_Inlet	7318	5460	1858	5462	1856

The marginal seas in the Atlantic and Pacific make the 2017 deficits to average: especially Barents, Kara, Bering and Okhotsk. 2017 Surpluses in Greenland Sea and Baffin Bay are smaller, but make most of the difference with 2006.

2017 Outlook

March this year averaged 14.509 M Km2 compared to the 11 year average of 14.986 M km2, a deficit of 478k km2 or 3.2% down. That suggests that a typical melt later this year would result in a minimum of about 4.5 or 4.6 M km2, slightly down from the 11 year average of 4.8M km2.

Sea Ice Index (SII) typically shows less ice than MASIE, and SII reports a 2017 March average ice extent of 14.273 M km2 compared to SII 11 year March average of 14.842, a drop of 569k km2 or 3.8%. Folks relying on SII may be expecting a lower September minimum, perhaps even breaking the present plateau of ice extents since 2007. That remains to be seen.

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April 1, 2017 at 04:58AM

Uncategorized 1 Apr 2017

Will EPA’s Scientific Integrity Office Censor EPA Chief?

via The Global Warming Policy Forum (GWPF)
http://www.thegwpf.com

The U.S. Environmental Protection Agency’s scientific integrity watchdog is reviewing whether EPA chief Scott Pruitt violated the agency’s policies when he said in a television interview he does not believe carbon dioxide is driving global climate change, according to an email seen by Reuters on Friday.

Lawyers for environmental group the Sierra Club had asked the EPA’s Office of Inspector General to check whether Pruitt violated policy when he told a CNBC interviewer on March 9, “I would not agree that it’s a primary contributor to the global warming that we see.”

The EPA Inspector General’s office responded to the Sierra Club on Thursday in an email, saying it had referred the matter to the EPA’s Scientific Integrity Officer, Francesca Grifo, for review.

“If after the SIO review, she concludes there is some aspect of the letter itself, or her findings or conclusions that she believes are appropriate for further consideration by the OIG, she will so notify the OIG,” the email stated.

A spokeswoman for the EPA defended Pruitt’s comments.

“Administrator Pruitt makes no apologies for having a candid dialogue about climate science and commonsense regulations that will protect our environment, without creating unnecessary regulatory burdens that kill jobs,” said Liz Bowman in an emailed statement.

“Differing views and opinions on scientific and technical matters is a legitimate and necessary part of EPA’s decision-making process, which is consistent with EPA’s scientific integrity policy that was in place even during the Obama administration,” she added.

The EPA website says its scientific integrity policy requires EPA officials and staff to ensure the agency’s work respects the findings of the broader scientific community.

Full story

via The Global Warming Policy Forum (GWPF) http://www.thegwpf.com

April 1, 2017 at 04:58AM

Uncategorized 1 Apr 2017

Remembering the Incredible New England Snowstorms of March 1956

via Watts Up With That?
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When I wrote my recent post The 300th Anniversary of the Great Colonial Snowcover of 1717, I didn’t realize that one of the rivals to March 1717 was relatively recent.

March 1956 started with an unremarkable snow cover at the Blue Hill Weather Observatory a little south of Boston, Massachusetts. However, snow storms in the second half of the month brought the month’s snowfall to an impressive 49.4″ (125.5 cm).

The following is a summary from Charles Orloff of Blue Hill on a paper by Conrad P. Mooka and Kenneth S. Norquest.

Blue Hill Observatory
Sky Mail
March 2017

Remembering the Incredible Snowstorms
of March 1956

The recent snowstorm this March brings back memories of the big snows of March 1956. In New England winter can still rule in March and heavy snows can indeed occur. Even April can see heavy snowfalls – a future SkyMail will talk about that month.

March 1956 started with 6.4″ (16.3 cm) of snow on the ground at Blue Hill Observatory. By the end of the month, three 12 inch plus snowstorms had blanked the Northeast bringing the monthly total to 49.4″ (125.5 cm) making the winter of 1955-56 the third snowiest on the Observatory’s then 132 year record.

Of the three major snowfalls in March 1956 the storm from March 18-20th was the most significant with upwards of 20″ (51 cm) falling along the Northeast corridor and much of Southern New England. What was remarkable was that there were three snowstorms in March 1956 in a period of just 10 days. The storms started with a rather typical coastal development on March 14th which left 2.3″ (5.8) of snowfall at Blue Hill Observatory. The next storm was just two days later.

On Friday, March 16, 1956, by 1230 GMT the stage was set for the typical development of a coastal Low which often produces heavy snow and high winds in the Northeast. The North Atlantic States had been flooded with cold air due to eastward passage of a 1032-mb High from the Great Lakes region to Maine. Meanwhile, a wave, which developed in the West Gulf on the trailing polar front, had deepened and moved northeastward to eastern Kentucky. This was attended by widespread heavy rains in the Southeastern States and snow through the Ohio Valley eastward to southern New Jersey. By this time the typical pattern of development was evident. A warm front lay along the Carolina coast, then extended eastward north of Bermuda. An area of 3-hourly pressure falls of 4 to 5 mb, concentrated in eastern North Carolina and southeastern Virginia, strongly indicated a secondary development on the coast. By 0030 GMT, March 17, the low center in eastern Kentucky had entirely filled and the secondary Low had formed and deepened to 984 mb just off Atlantic City, N. J. The pressure at Atlantic City fell 25 mb in just 12 hours, indicating the explosive nature of the cyclogenesis which took place. Snow had now spread over all of the North Atlantic States, attended by strong winds with gales on the coast. By 0630 GMT, March 17, the center was 970 mb just east of Nantucket. Snow and strong winds covered the Northeastern States and gales continued on the New England coast. By 1230 GMT, March 17, the storm was well out to sea some 380 miles east of Boston. This storm was a nearly perfect example of the rapid development of a coastal storm. It deposited 14″ of new snow at Albany, N. Y., 6″ at Hartford, Conn., and 10″ at Concord, N. H., New York City and Boston (35, 15, and 25 cm). In just 12 hours the intense storm moved from a position off the coast near Atlantic City to 380 miles east of Boston. Snowfall at Blue Hill Observatory measured 12.9″ (32.8 cm).

19560319

All of this set the stage for the biggest storm which occurred from March 18-20th. By early morning of the 18th (1230 GMT) the area of snowfall attending the developing southern low centers over eastern Kentucky and southern West Virginia had enlarged to cover the Ohio Valley and had spread eastward over the Appalachians to cover most of the mid-Atlantic states. Precipitation fell as rain over southern Maryland and southern Virginia, while snow was falling over the remainder. Snow had spread from southern New Jersey, beginning at 1545 GMT at Newark and 1603 GMT at New York City. At this time one low center was moving eastward near Quantico, Va., while another was also moving eastward near Danville, Va. During the next 6 hours there was little change in the area of precipitation. Showers and thunderstorms moved eastward across southern Virginia and eastern North Carolina as the southern low center moved to the coast near Elizabeth City, N. C. and began to strengthen into a dangerous gale. Snow continued from Maryland and Delaware northward over Pennsylvania and into Long Island as well as westward to Cincinnati, Ohio, as the northern Low center moved to southern Delaware. By 0630 GMT on the 19th the surface Low system was off the coast, some distance southeast of New Jersey, moving northeastward. Snowfall continued over the New York City area, New Jersey, Delaware, Maryland, and eastern Pennsylvania. On the 19th the snow spread over Southern New England. Meanwhile, the low pressure cyclonic center moved northeastward along the coast at an ever-slowing rate toward Nantucket, finally passing to the northeast of that point and filling on the 20th, while a new center formed farther east near Sable Island. It is interesting to note that the duration of precipitation in the form of snow at Philadelphia, Trenton, Atlantic City, Newark, and New York City (Battery) ranged from 31 hours at Philadelphia to 35 hours at Atlantic City. Farther east, over Southern New England, the duration ranged from 26 hours at New Haven to 24 hours at Boston. In spite of this, the depth of new snow added by the storm was remarkably uniform, measuring 12 to 13″ (~32 cm) at Trenton, New York City, New Haven, Bradley Field (Hartford), and Boston. A notable exception was the 18″ (46 cm) which fell at Newark. Snowfall at Blue Hill was 17.5″ (44.0 cm) with a total snowfall on the ground on the 20th of 25.3″ (64.3 cm).

All in all, this was one of the most severe and deadly snowstorms in Southern New England history. Approximately 162 people were killed and most towns were left paralyzed under deep snow drifts as high as 14 feet (4+ meters).

As if this wasn’t enough the blizzard of March 18-20 was followed by another 12.3″ (31.2 cm) snowfall on March 24th with a final 3″ (7.6 cm) falling from the 29th to the 30th. Many of us remember shoveling much of the month, fortunately under a warm March sun!

The Blue Hill Observatory was built atop a hill a little south of Boston in 1885. It was the first weather observatory built in the United States and has an unbroken weather record.

Some of their early “high tech” equipment is still in use although “antique” is sometimes the better description now. If you’re in the area, check their schedule and stop in for a visit. Whether there or not, check out their store, especially their books, or donate some money to help make up for cuts in state support.

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