Showing posts with label pressure. Show all posts
Showing posts with label pressure. Show all posts

Friday, July 19, 2013

Arctic Ocean Events - Videos by Paul Beckwith

by Paul Beckwith


Massive Arctic cyclone effect on sea ice in August 2012
Part 1: August 1st to 16th, 2012
http://www.youtube.com/watch?v=nli47-9dT5o

Arctic sea ice motion (speed and direction) is compared to sea ice thickness from August 1st to August 16th, 2012. Sea ice motion is then compared to meteorology (500 mb pressure heights and 200 mb vector winds).



Massive Arctic cyclone effect on sea ice in August 2012
Part 2: August 1st to 16th, 2012
http://www.youtube.com/watch?v=WqwIVEpSg3w

Northern hemisphere meteorology (500mb pressure heights) and Arctic sea ice concentration compared to SST (sea surface temperatures) are examined from August 1st to August 16th, 2012 encompassing the mass persistent cyclone.



Massive Arctic cyclone effect on sea ice in August 2012
Part 3: August 1st to 16th, 2012
http://www.youtube.com/watch?v=HjYxRV0fzz4

Arctic basin SSS (sea surface salinity) is compared to SSH (sea surface height) during the period August 1st to August 16th, 2012 which encompassed a massive persistent cyclone. Detailed meteorology is also examined (tropopause temperature + pressure, surface precipitable water + pressure). Also examined is ocean profile salinity and temperature from an ice tethered buoy.



Massive Arctic cyclone effect on sea ice in August 2012
Part 4:  August 1st to 16th, 2012
http://www.youtube.com/watch?v=aAJRIV8YITY

The jet streams in the Arctic ocean basin are shown (200mb vector winds) from NOAA/ESRL daily data, as well as from 4 times daily data from SFSU. The data is given from August 1st to August 16th, 2012 which encompasses the massive Arctic cyclone.



2013

Arctic sea ice thickness + motion
May 14th to June 10th, 2013
http://www.youtube.com/watch?v=5ljHI0VITgk

Arctic sea ice data from May 14 to June 10, 2013
Left pane shows Arctic sea ice thickness; right pane shows sea ice motion (direction and speed).



Arctic sea ice thickness + motion
July 1st to 17th 2013
http://www.youtube.com/watch?v=cUZr51_yW5s

Arctic sea ice data from July 1st to July 17th, 2013. Left pane shows the Arctic sea ice thickness; right pane shows sea ice motion (direction and speed).



Sea ice concentration, temperature, salinity, and height;
July 1st to 18th, 2013
http://www.youtube.com/watch?v=icUtGqpkFx8

Arctic ocean data from US Navy for
1) sea ice concentration,
2) sea surface temperature (SST),
3) sea surface salinity (SSS), and
4) sea surface height (SSH)



Jet streams
July 1st to July 17th 2013
http://www.youtube.com/watch?v=IFbJCFVSiPI

Northern hemisphere (NH) jet streams are shown from two sources:
1) NOAA/ESRL data collected daily, and
2) SFSU data collect every 6 hours. Data is given for the time period from July 1st to July 17th, 2013.



Meteorology
July 1st to 18th 2013
http://www.youtube.com/watch?v=LONJT8JbM7I

The following meteorology plots are shown for time period July 1st to July 18th, 2013 over the Arctic Ocean between 60 degrees N and 90 degrees N:
1) 500mb pressure levels,
2) 200mb vector winds (jet streams),
3) precipitable water, and
4) tropopause temperatures.

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Friday, October 26, 2012

Amplification of climate change in the Arctic

In contrast to multi-year old ice, first-year old ice—ice that formed only since the last melt season—is thinner, saltier, and much more prone to melt.


Over the years, the loss of sea ice has become especially manifest in the older ice, as illustrated by the image below.


Salt content and hardness play a part in multi-year ice’s resistance to melt, explains a recent NOAA article, but the main characteristic that allows the ice to survive the melt season is thickness.

Screenshots from: PIOMAS Arctic Sea Ice Thickness Simulation 1978-2011
The decline in thickness over the years goes a long way to explain the self-reinforcing character of sea ice decline in the Arctic.

As another recent NOAA article describes, there is “something extra” behind the record ice retreats of the past 6 years: each June, the prevailing winds shifted from their normal west-to-east direction and instead blew strongly from the south across the Bering and Chuchki Seas (left on the image below), over the North Pole, and out toward Fram Strait. (The length of the lines is qualitative: longer lines mean stronger winds.)

Average June wind vectors in 2007-2012 (orange) compared to 1981-2010 average (white) based on NCEP reanalysis data provided by Physical Sciences Division at NOAA ESRL. Map by Dan Pisut, NOAA Environmental Visualization Lab.

The image below shows the unusual air pressure patterns that gave rise to the wind shift. Air pressure across the Arctic in Junes from 2007-2012 was completely lopsided, with two pockets of higher-than-average pressure sprawled across the North American Arctic and Greenland. These areas of high pressure act like boulders in a river. They slow and disrupt the normal westerly flow of the wind, forcing it to make, large, meandering detours to the north or south.

Average geopotential height anomaly at 700 millibar pressure level in Junes from 2007-2012 compared to the long-term average (1981-2010) based on NCEP reanalysis data provided by PSD at NOAA ESRL. Orange colors are higher-than-average pressure; blue is lower-than-average pressure.     Map by Dan Pisut, NOAA Environmental Visualization Lab.
Arctic oceanographer and his NOAA colleagues think these “blocking highs” on the North American side of the Arctic created the unusually strong southerly flow that brought warm air into the central Arctic and over Greenland. The persistent southerly winds would help explain both the record low sea ice extent in summer 2012, as well as the island-wide melting of the surface of the Greenland Ice Sheet, which satellites detected in July 2012.

“This story started with us trying to figure out why the sea ice extents of the past 6 years or so have been so much lower than we would expect based on the long-term warming trend alone,” says Overland, “and we think this unusual circulation of the Arctic atmosphere is major part of it.”

Why, asks Overland, have these high pressure patterns have been forming so consistently each June for the past six years? The repeated appearance of these atmospheric features each June is so unusual that it’s the equivalent of a 1-in-a-1000 event. Can this be attributed to natural variability?

Instead, Overland’s hunch is that the cause is a change in the atmosphere that is itself connected to climate change in some way, possibly linked to record and near-record low June snow cover in the Canadian Arctic in recent years. “We don’t know that part of the story yet,” he says, “but this would certainly be the type of amplification of climate change [warming triggers changes that lead to more warming] we have been expecting to see in the Arctic.”

References

- Arctic Sea Ice Getting Thinner, Younger
http://www.climatewatch.noaa.gov/article/2012/arctic-sea-ice-getting-thinner-younger

- June wind shift a little something extra behind recent Arctic ice losses
http://www.climatewatch.noaa.gov/article/2012/june-wind-shift-a-little-something-extra-behind-recent-arctic-ice-losses

- Poles apart: A record-breaking summer and winter
http://nsidc.org/arcticseaicenews/2012/10/poles-apart-a-record-breaking-summer-and-winter/

- PIOMAS Arctic Sea Ice Thickness Simulation 1978-2011, published Sep 14, 2012 by ArctischePinguin
https://www.youtube.com/watch?v=G1TLzgSlGtQ

Related

- Arctic summer wind shift
http://arctic-news.blogspot.com/2012/10/arctic-summer-wind-shift.html

- The recent shift in early summer Arctic atmospheric circulation
http://www.agu.org/pubs/crossref/2012/2012GL053268.shtml

- Presentation by Dr. Jennifer Francis, Rutgers University
https://www.youtube.com/watch?v=RtRvcXUIyZg
http://marine.rutgers.edu/~francis/pres/Francis_Vavrus_2012GL051000_pub.pdf
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