Big Cheer for CryoSat-2

30/06/2010

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Let’s Hear a Big Cheer for CryoSat-2

An early result from ESA’s CryoSat-2 mission detects a “scoop”, or drop, near the edge of Antarctica’s Ross Ice Shelf, probably due to melting at the base of the 400-metre thick slab of floating ice. There are also clear indications of the variable thickness of sea ice in the adjacent ocean. The vertical scale appears to be very different over the shelf and over the sea.

No branch of climate physics has been more befuddled by propaganda than the monitoring of the Earth’s cryosphere. Ordinary melting at glacier snouts that has happened every spring for thousands of years is nowadays captured by TV cameras and presented as evidence of runaway global warming. Dutiful journalists report reductions in Arctic sea ice but ignore increases in Antarctic sea ice. And scientists argue about how thick the sea ice is.

Thank goodness that the European Space Agency’s CryoSat-2 satellite is at last commissioning in orbit. Duncan Wingham of University College London, leader of the project, released the Ross Ice Shelf image yesterday at ESA’s Living Planet Symposium in Bergen.

The mission had a difficult history, with the original CryoSat being lost on launch in 2004, and CryoSat-2 going into an incorrect orbit in April of this year. But now we can expect much more accurate radar measurements of ice altitude over land and ice shelves, and of “freeboard” in the case of sea ice, which is a measure of its thickness. Perhaps we’ll soon begin to get the hard facts about “polar melting”. They’re long overdue.

For another take on “polar melting”, see my history of the Greenland ice sheet at https://calderup.wordpress.com/2010/05/06/warming-of-greenland/


Sun still sulks

20/06/2010

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The Sun still sulks

Two magnetograms from the ESA-NASA SOHO spacecraft contrast the Sun’s liveliness of exactly 10 years ago (20 June 2000) on the left with its feeble performance today (20 June 2010) on the right. In these images made with Stanford’s Michelson Doppler Interferometer, north magnetic polarity is white, south magnetic polarity is black.

Solstice sunrise over Stonehenge 2005. Credit: User: Solipsist.

As many thousands flock to Stonehenge for tomorrow’s summer solstice, this is a moment to ask for the umpteenth time what the Sun is up to. The mean sunspot number in June 2000 was 119, today it is 28, with the spots clustered in the northern region showing most magnetic activity. Since 2004 there have been 803 days with no sunspots at all (35 in 2010, 260 in 2009). During a typical sunspot minimum there are fewer than 500 spotless days.

In the current issue of the Royal Astronomical Society’s magazine Astronomy and Geophysics, Nigel Weiss of Cambridge considers the long-term variability of the Sun and alternative theories about it, especially concerning “grand maxima” in activity like that in the 20th Century, and “grand minima” like the Maunder Minimum of 300 years ago associated with the Little Ice Age. Weiss’s conclusion is that there’s a 40 % chance the current grand maximum will be followed by a grand minimum.

As for the climatic implications, Weiss and I agreed to differ some years ago. Although we both say that the Intergovernmental Panel on Climate Change underestimates the influence of the Sun, Weiss thinks it can’t compete with man-made global warming. His article ends:

Even if the Sun does enter a new Maunder-like grand minimum, any cooling effect will be small compared with the warming produced by anthropogenic greenhouse gases.

Contrast that with Henrik Svensmark’s conclusion in an article for the Danish newspaper Jyllands-Posten.

That the Sun might now fall asleep in a deep minimum was suggested by solar scientists at a meeting in Kiruna in Sweden two years ago. So when Nigel Calder and I updated our book The Chilling Stars, we wrote a little provocatively that “we are advising our friends to enjoy global warming while it lasts.”

In fact global warming has stopped and a cooling is beginning. Mojib Latif from the University of Kiel argued at the recent UN World Climate Conference in Geneva that the cooling may continue through the next 10 to 20 years. His explanation was a natural change in the North Atlantic circulation, not in solar activity. But no matter how you interpret them, natural variations in climate are making a comeback.

The outcome may be that the Sun itself will demonstrate its importance for climate and so challenge the theories of global warming. No climate model has predicted a cooling of the Earth – quite the contrary. And this means that the projections of future climate are unreliable. A forecast saying it may be either warmer or colder for 50 years is not very useful, and science is not yet able to predict solar activity.

So in many ways we stand at a crossroads. The near future will be extremely interesting. I think it is important to accept that Nature pays no heed to what we humans think about it. Will the greenhouse theory survive a significant cooling of the Earth? Not in its current dominant form. Unfortunately, tomorrow’s climate challenges will be quite different from the greenhouse theory’s predictions. Perhaps it will become fashionable again to investigate the Sun’s impact on our climate.

References

N. Weiss, “Modulation of the Sunspot Cycle”, Astronomy and Geophysics, Vol. 51, pp. 3.9-3.15, 2010

H. Svensmark: “While the Sun sleeps” (in Danish), Jyllands-Posten, 9 September, 2009

For a related post on this blog see https://calderup.wordpress.com/2010/05/12/puzzling-sun/

Postscript on the Song of the Sun

I see that Sheffield solar physicists now generate music from observations of the magnetic coronal loops. Read about it (and hear it): http://www.telegraph.co.uk/science/space/7840201/Music-of-the-sun-recorded-by-scientists.html

For an earlier Song of the Sun, using its internal vibrations seen by SOHO’s MDI, click on the second item here (but beware – it’s about 18 MB with visuals) http://www.esa.int/esaSC/SEMLAJWO4HD_index_0.html


Aircraft seed clouds

14/06/2010

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Aircraft can seed precipitation from clouds

A hole left in a cloud-layer after an aircraft has passed through, provoking snowfall – or rainfall if the ice crystals melt on the way down to the ground. Photo: hole in altocumulus clouds over Mobile, Alabama, from 35 mm negative film, by Alan Sealls, chief meteorologist, WKRG-TV, Pensacola, Florida.

In 2007, meteorologists noticed a connection between snowfall near Denver, Colorado, and a turboprop aircraft descending through a cloud layer. The snowfall, in a band about 20 miles long and 2.5 miles wide, continued for about 45 minutes, resulting in about two inches of snow on the ground. They eventually figured out that when a turboprop plane flies through such a cloud layer with supercooled water droplets at about -15 degrees C, the tips of its propellers cause the air to expand, cool and freeze the droplets. Since then they have concluded that the expansion of air over a jet aircraft’s wings can have the same effect in colder conditions, -20 to -25C. Aircraft seeding may be particularly common in the northwestern USA and Western Europe.

Andrew Heymsfield, lead author of the report, is from National Center for Atmospheric Research (NCAR) in Boulder, Colorado.

References

Andrew Heymsfield et al., “Aircraft-Induced Hole Punch and Canal Clouds: Inadvertent Cloud Seeding”, Bulletin of the American Meteorological Society, June 2010

More info and a video here: http://www2.ucar.edu/news/mysterious-clouds-produced-when-aircraft-inadvertently-cause-rain-or-snow




Sprites fight

11/06/2010

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Sprites fight in the upper atmosphere

Two enormous electrical discharges called sprites are seen brushing together in this conflation of a series of high-speed TV images, looking out over the sea from Catalonia towards Italy. The scale shows the heights above sea level, with the whole phenomenon stretching from 50 to 83 km altitude, and all over in a matter of milliseconds. Source: Joan Montanyà et al., see references.

The following video is in Spanish, but it includes the event shown as a still image above, fully animated. http://plataformasinc.es/index.php/esl/videos/detalle/54380

You can see other video examples of high-altitude  phenomena called sprites, elves and jets in the first image on this ESA page http://www.esa.int/esaCP/SEM4HV4Y3EE_index_0.html

Sprites, elves and jets link thunderstorms and the upper atmosphere, as in this diagram from the National Space Institute in the Technical University of Denmark (DTU).

If “elve” (not “elf”) bothers you in the diagram, be aware that elves is a joky acronym: “emissions of light and VLF perturbations from electromagnetic sources”.

The European Space Agency is preparing an experiment called the Atmosphere-Space Interactions Monitor (ASIM) to observe these events from the International Space Station. The word is that it’s due to fly in 2013.

As for the link to climate physics, here’s a comment made by the ASIM principal investigator a few years ago:

“The question is how are these giant flashes of lightning created and how often do they take place”, says senior scientist Torben Neubert, head of the project at the Danish National Space Centre.

It may well be that the large electrical bursts remove ozone from the atmosphere, and in so doing influence the climate. “We need to understand the natural processes which influence the atmosphere and this can help us decide which changes in the climate are man-made”, Torben Neubert states.

It’s hard to resist pointing out a moral in this tale. Seafarers and mountain-dwellers have noticed these high-altitude lightning flashes for centuries or millennia. They may have provoked some religious experiences. Back in 1925 C.T.R. Wilson, who invented the cloud chamber, predicted the creation of very energetic “runaway” electrons by thunderstorms. In 1956, at the age of 87, Wilson at last saw the high-altitude phenomenon for himself. So did airline pilots and UFO watchers.

Yet our know-it-all meteorologists scorned the existence of sprites until 1990, when 74-year-old John Winckler from the University of Minnesota reported that he had caught a brief image with a low-light TV camera that he was testing. So what else don’t we know, or what are we ignoring, about events and processes at the Earth’s frontier with outer space?

For an impression of how lively this field of research now is, see the titles in http://hydrology.agu.org/contents/sc/ViewCollection.do?collectionCode=THUNDER1&journalCode=JA

References

J. Montanyà et al.,”Intensified high-speed video recordings of sprites and elves over the western Mediterranean Sea during winter thunderstorms.” Journal of Geophysical Research 115, A00E18, 8 PP., 2010

Press releases are available in English http://www.alphagalileo.org/ViewItem.aspx?ItemId=78164&CultureCode=en

and in Spanish http://www.plataformasinc.es/index.php/esl/Noticias/Graban-en-video-a-los-duendes-y-elfos-de-las-tormentas

Neubert quote from http://www.esa.int/esaCP/SEM4HV4Y3EE_index_0.html

C. T. R. Wilson, “The acceleration of Beta-particles in strong electric fields such as those of thunderclouds”, Proc. Camb. Philos. Soc., 22, 534, 1925

J.R. Winckler et al., “Television image of a large upward electrical discharge above a thunderstorm”, Science, 249, 48-51, 1990.


Soil H2O from space

06/06/2010

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Soil moisture around the Amazon, gauged from space

A plot of microwave “brightness temperatures” measures the water content of the soil around the lower Amazon. This is an early result from Europe's Soil Moisture and Ocean Salinity satellite, SMOS, launched in November 2009 and formally operational since late May 2010. It's a sample of what is now becoming available globally every 3 days, and SMOS should help to fill a huge gap in human knowledge of the water cycle. Credit: ESA/SMOS.

Despite repeated claims that the weather system is known well enough for making multi-decade forecasts of the changing climate, the ignorance can be truly profound. The global water cycle is a key theme where understanding is poor and reliable data are notoriously scanty. The Intergovernmental Panel on Climate Change avoids forthright language that might dismay those who want to treat its findings as gospel, yet in relevant parts of Working Group I’s 2007 report there are hints of desperation. See Section 3.3: “Changes in Surface Climate: Precipitation, Drought and Surface Hydrology”, available here: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-3.html

Soil moisture is crucial

  • as a climate factor in its own right, vital for natural and cultivated plant growth, and for the management of water resources
  • as a strong influence on the global carbon cycle by its contribution to terrestrial photosynthesis
  • as a way station in the hydrological system’s non-stop traffic between rainfall, evaporation, transpiration from plants, and run-off into streams and rivers.

If you want ever to model the water cycle accurately, you really must know the soil moisture content. The European Space Agency claims for SMOS an accuracy of 4%, “comparable to detecting one teaspoon of water mixed into a handful of soil” from an altitude of 760 km. A calculation gives the water content in soil to a depth of 1-2 metres – the root zone.

How’s it done? The presence of water affects the electromagnetic behaviour of soil, and hence the intensity of radio microwaves that it radiates. But the long wavelength, about 20 cm, of the most useful microwaves implies that you need a large radio telescope in space to observe them well.

SMOS, pictured by ESA

The L-band radiometer on SMOS, called MIRAS, uses the radio astronomers’ technique of aperture synthesis. It simulates a much bigger antenna with 69 small antennas strung out along three arms arranged in a Y, and so resolves areas 50 km wide within a hexagon on the Earth’s surface about 1000 km across.

The same instrument on SMOS gauges the saltiness of sea water, using the electromagnetic contrast between pure water and salty water – hence “Ocean Salinity” in the mission’s name. But that’s another story.

Good luck to mission manager Susanne Mecklenburg, mission scientist Matthias Drusch, and all the SMOS team.



Pacific islands grow

04/06/2010

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Pacific islands are growing

Kiribati, where the most densely populated islands grew in area by 12.5 to 30 % during recent decades, according to historical aerial photos and satellite images. Photo: World Bank.

Along with drowning polar bears, drowning islands are emblems of global warming propaganda. For example, the World Bank uses this very picture to say the Pacific islands of Kiribati are threatened by climate change. How disconcerting for the warmists, then, is the finding by Arthur Webb, South Pacific Applied Geoscience Commission, Fiji, and Paul Kench of Auckland University. They report (surprise, surprise) that coral grows.

Here’s the abstract of Webb and Kench’s paper, with the key result highlighted.

Low-lying atoll islands are widely perceived to erode in response to measured and future sea level rise. Using historical aerial photography and satellite images this study presents the first quantitative analysis of physical changes in 27 atoll islands in the central Pacific over a 19 to 61 year period. This period of analysis corresponds with instrumental records that show a rate of sea level rise of 2.0 mm.y-1 in the Pacific. Results show that 86% of islands remained stable (43%) or increased in area (43%) over the timeframe of analysis. Largest decadal rates of increase in island area range between 0.1 to 5.6 hectares. Only 14% of study islands exhibited a net reduction in island area. Despite small net changes in area, islands exhibited larger gross changes. This was expressed as changes in the planform configuration and position of islands on reef platforms. Modes of island change included: ocean shoreline displacement toward the lagoon; lagoon shoreline progradation; and, extension of the ends of elongate islands. Collectively these adjustments represent net lagoonward migration of islands in 65% of cases. Results contradict existing paradigms of island response and have significant implications for the consideration of island stability under ongoing sea level rise in the central Pacific. First, islands are geomorphologically persistent features on atoll reef platforms and can increase in island area despite sea level change. Second; islands are dynamic landforms that undergo a range of physical adjustments in responses to changing boundary conditions, of which sea level is just one factor. Third, erosion of island shorelines must be reconsidered in the context of physical adjustments of the entire island shoreline as erosion may be balanced by progradation on other sectors of shorelines. Results indicate that the style and magnitude of geomorphic change will vary between islands. Therefore, Island nations must place a high priority on resolving the precise styles and rates of change that will occur over the next century and reconsider the implications for adaption.

Reference: A.P. Webb & D.S. Kench, “The dynamic response of reef islands to sea level rise: evidence from multi-decadal analysis of island change in the central Pacific”, Global and Planetary Change, 2010 doi:10.1016/j.gloplacha.2010.05.003


Stars rush about

02/06/2010

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Young stars rush about like naughty children

Flicking between images of a star cluster taken by the WFPC2 camera in the Hubble Space Telescope in 1997 and 2007 reveals individual stars moving, like those seen in the boxes. In two years of close examination, German astronomers have gauged the motions of more than 700 stars and found them to be faster than expected. Most of the cluster stars move by less than 1/10 of a pixel over the ten-year period, which is not discernible by eye. The object is the massive compact Young Cluster, NGC 3603, lying 20,000 light-years away in the Carina spiral arm of the Galaxy. Credit: NASA, ESA and Wolfgang Brandner (MPIA), Boyke Rochau (MPIA) and Andrea Stolte (University of Cologne)

Extracts from the Hubble press release

http://www.spacetelescope.org/news/heic1009/

[If the flicking doesn’t work, go to this Hubble url to see it offered, on the right. NC]

With a mass of more than 10,000 suns packed into a volume with a diameter of a mere three light-years, the massive young star cluster in the nebula NGC 3603 is one of the most compact stellar clusters in the Milky Way and an ideal place to test theories for their formation.

A team of astronomers from the Max-Planck Institute for Astronomy in Heidelberg and the University of Cologne led by Wolfgang Brandner (MPIA) wanted to track the movement of the cluster’s many stars. Such a study could reveal whether the stars were in the process of drifting apart, or about to settle down.

The results for the motion of these cluster stars were surprising: this very massive star cluster has not yet settled down. Instead, the stars’ velocities were independent of their mass and thus still reflect conditions from the time the cluster was formed, approximately one million years ago.

In the long term such massive compact star clusters may lead to the development of the huge balls of stars known as globular clusters, whose tightly packed stars remain held together by gravity for billions of years.

Wolfgang Brandner (MPIA): This is the first time we have been able to measure precise stellar motions in such a compact young star cluster.

Andrea Stolte (Cologne): This is key information for astronomers trying to understand how such clusters are formed, and how they evolve.

Boyke Rochau (MPIA) Our measurements have a precision of 27 millionths of an arcsecond per year. This tiny angle corresponds to the apparent thickness of a human hair seen from a distance of 800 km.