Strong La Niña in December 2010

Peruvian fisherman named El Niño (Spanish for “the boy child”) after the Christ child because the climate phenomenon usually shows up around Christmastime. But its counterpart, La Niña, is the gift giver, bringing cold, nutrient-rich water to the equatorial Pacific off South America. Those nutrients are a boon to marine life, supporting a larger fish population and increasing the fishermen's catch. Fishermen might expect a good year ahead, as a strong La Niña is now dominating the Pacific Ocean.

“This is one of the strongest La Niña events in the past half century, and will likely persist into the northern hemisphere summer,” says Bill Patzert, an oceanographer and climatologist at NASA’s Jet Propulsion Laboratory. “Climatic impacts include heavy rains and flooding, which has damaged crops and flooded mines in Australia and Asia. It also has resulted in flooding in northern South America and drought conditions in Argentina. This powerful little lady is spreading her curses and blessings across the planet. She’s the real deal.”

La Niña’s cold water signal is strong in the top two images. The left image shows ocean surface temperatures on December 15, 2010, as measured by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on NASA’s Aqua satellite. In December 2010, sea surface temperatures were colder than average across the equatorial Pacific.

The right image depicts the heat content of the ocean surface between December 14 and 16, 2010, as observed by the U.S.-French Ocean Surface Topography Mission (OSTM)/Jason-2 satellite. Water expands as it warms, so warmer water has a higher surface elevation than cooler water. The blue valley streaking across the middle of the sea surface height image is the signature of La Niña. The intensity of the cold water and the depth and extent of the valley point to an intense event.

Like El Niño, La Niña comes from changes in both the ocean and the atmosphere. High pressure usually dominates the atmosphere over the eastern Pacific, while low pressure tends to reign in the west. The pressure difference creates the trade winds, which blow surface water across the equatorial Pacific to a pool of warm water in the west. Cooler deep water wells up to replace the surface water. During La Niña events, the pressure difference and the resulting trade winds are stronger. The more intense winds push more water west, where it builds up north of Australia. Meanwhile, more cold water wells up in the central and eastern Pacific.

La Niña occurs only when both the ocean and the atmosphere change together, and in 2010, they have, says oceanographer David Adamec of NASA’s Goddard Space Flight Center. The unusual ocean temperatures and imbalance in air pressures alter weather patterns across the world.

The lower image shows some of the unusual weather La Niña brought in December 2010, as observed by the Tropical Rainfall Measuring Mission (TRMM) between November 23 and December 23, 2010. The image shows rainfall totals compared to average rainfall for the period, with above-average rain in blue and less-than-average rainfall in brown.

“Weather effects are strong in the western Pacific,” says Adamec. “Australia is flooding in many areas.” La Niña rainfall patterns are also evident in the stark horseshoe-shaped region of unusually dry weather in the central Pacific.

La Niña typically affects weather patterns in North America beginning in January. “For ‘normal’ effects in the U.S., look for cold in the Upper Plains, dry and warm weather in California, dry weather in the southeast, especially Florida, and unusually soggy weather in the Northwest,“ says Adamec.

Because such a wide swath of the Pacific is cold, La Niña tends to keep a lid on global temperatures. 2010, however, was still shaping up to be the hottest year on record in spite of La Niña, according to scientists from NASA Goddard Institute for Space Studies.

1.
References
2. Climate Prediction Center/NCEP. (2010, December 20). ENSO cycle: Recent evolution, current status and predictions. National Oceanic and Atmospheric Administration.
3. Hansen, J., Ruedy, R. Sato, M., and Lo, K. (2010, December 13). 2010—Global temperature and Europe’s frigid air. NASA Goddard Institute for Space Studies. Accessed December 23, 2010.
4. NASA Earth Observatory. (n.d.) La Niña. Accessed December 21, 2010.

NASA Earth Observatory images created by Jesse Allen, using JASON-2 data provided courtesy of Akiko Hayashi (NASA/JPL), AMSR-E data processed and provided by Chelle Gentemann and Frank Wentz, Remote Sensing Systems, and near-real-time data rainfall data provided courtesy of TRMM Science Data and Information System at Goddard Space Flight Center. Caption by Holli Riebeek.

Instrument:
JASON-2
Nasa Earth Observatory del 24 dicembre 2010

A Snapshot of Particles in the Air

Tiny solid and liquid particles—some you can see, some you cannot—can be found in the air everywhere on the planet, at any time of year. The amount of particles, known to scientists as aerosols, fluctuates naturally with the seasons and natural events, as well as with human activities. Dust storms, volcanic eruptions, wildfires, and salt spray from the winds over the ocean are the most common and abundant producers of aerosols. Humans generate them, too, through the burning of fossil fuels, manufacturing processes, and fires for cooking, heating, and agricultural clearing.

This map shows the global distribution of aerosols in August 2010, and the proportion of those aerosols that are large or small. Yellow areas are predominantly coarse particles, like dust and sea salt, while red areas are mainly fine aerosols from smoke or pollution. Gray indicates areas with no data. The brighter or more intense the color, the higher the concentration of aerosols.

The map was compiled from data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites.

Yellow bands—larger, coarse particles—around the Middle East, North Africa, and western North America likely indicate dust and sand storms as the northern hemisphere reaches the driest time of year. The bright red areas in Russia and much of South America reveal the intense wildfires and some agricultural burning, which coincided with hot summers and drought in several regions. The red patches in western Canada spring from summer wildfires, while China was likely coping with a combination of fire, dust, and pollution events. It is unclear what was happening in western Africa.

Of all the particles that fill our lungs on any given day, the most dangerous are the small ones. Aerosol particles smaller than 2.5 micrometers pose the greatest risk to human health because they are small enough to be breathed deep into the lungs and, in some cases, enter the blood stream. These fine particles, about 30 times smaller than the width of a human hair, are also a major cause of poor visibility.

NASA map by Robert Simmon, based on MODIS data from NASA Earth Observations. Caption by Mike Carlowicz.

Instrument:
Terra - MODIS
Nasa Earth Observatory del 25 dicembre 2010

Hole Punch Clouds over West Virginia

Looking up on a chilly December morning in 2009, residents of rural West Virginia (southwest of Charleston) would have seen a halo of light bursting through the thin bank of clouds that hung overhead. The light was streaming through hole-punch clouds and canals, most likely created by passing airplanes. This image, taken by the Landsat-5 satellite on December 11, 2009, shows the unique conditions in which such holes form.

When airplanes, particularly propeller aircraft, pass through the clouds, they disturb the air. The air expands in the turbulence created by the propellers and wings. As the air expands, it cools, and the supercooled water droplets in the clouds freeze into ice. These ice crystals act as seeds for other water droplets to freeze onto. Over time, the water clouds around the disturbed area disappear and an ice cloud grows.

The clouds created in this manner take two different forms: hole-punch clouds and canals. The hole-punch clouds consist of an ice cloud surrounded by a halo of clear sky where the water in the clouds has frozen into ice and disappeared. Canals resemble contrails. They are long streaks where ice clouds are continuously being formed as the aircraft travels in the altocumulus cloud layer.

The image above was made with both infrared and visible light, in a combination that makes it possible to distinguish between water and ice clouds. The even cloud blanket is pale blue and pink, the warmer tones of water clouds. In the hole-punch clouds, however, we see the iridescent blue signature of ice, surrounded by a halo of clear sky. A similar blue streak from a canal runs across the top left.

The surrounding cloud bank is made up of altocumulus clouds, sitting at an altitude of 2,000 to 7,000 meters (6,600 – 23,000 feet), where temperatures ranged between minus five and minus twenty degrees Celsius, according to radiosonde data taken nearby. Despite the chill, this image reveals that the clouds were made of water, not ice.

1.
References
2. Heymsfield, A.J., Kennedy, P.C., Massie, S., Schmitt, S., Schmitt, C., Wang, Z., Haimov, S., and Rangno, A. (2010, June). Aircraft-induced hole punch and canal clouds, inadvertent cloud seeding. Bulletin of the American Meterological Society, 91 (6), 753-766.
3. NASA Earth Observatory. (2007, January 31). Hole punch clouds in Acadiana. Accessed November 15, 2010.
4. University of Wyoming Department of Atmospheric Science. (2009, December 11). Radiosonde data 72318 RNK Blacksburg observations at 00Z Dec 2009. Accessed November 15, 2010.

NASA image by Rob Simmon using Landsat 5 data from the USGS Global Visualization Viewer. Caption by Holli Riebeek with image interpretation courtesy Andrew Heymsfield.

Instrument:
Landsat 5
Nasa Earth Observatory del 28 dicembre 2010

Arctic Oscillation Chills US and Europe Posted

The first week of December was a chilly one for much of Europe and parts of the United States. This image shows the temperature of the land surface for December 3-10, 2010, compared to the average temperature for the same period between 2002 and 2009. The measurements are from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite.

Clearly, 2010 was cooler than average in northern Europe and the eastern United States. Greenland and parts of northern Canada, however, were exceptionally warm. This temperature pattern was caused by the Arctic Oscillation.

The Arctic Oscillation is a climate pattern that influences winter weather in the northern hemisphere. It describes the relationship between high pressure in the mid-latitudes and low pressure over the Arctic. When the pressure systems are weak, the difference between them is small, and air from the Arctic flows south, while warmer air seeps north. This is referred to as a negative Arctic Oscillation. Like December 2009, the Arctic Oscillation was negative in early December 2010. Cold air from the Arctic channeled south around a blocking system over Greenland, while Greenland and northern Canada heated up.

The unusual cold brought heavy snow to Northern Europe, stopping flights and trains early in December. Cold temperatures and snow also closed roads and schools in the eastern United States and Canada during the first week of December. The diagonal path of a powerful winter storm is visible as a streak of cold across the Upper Midwest of the United States.

1.
References
2. Associated Press. (2010, December 14). Bone-chilling cold plods into Northeast US. Accessed December 15, 2010.
3. BBC News. (2010, December 3). Europe’s deadly cold snap maintains grip. Accessed December 15, 2010.
4. Climate Prediction Center. (2010, December 15). Arctic Oscillation. NOAA National Weather Service. Accessed December 15, 2010.
5. CNN. (2010, December 2). Heavy snow creates European travel chaos. Accessed December 15, 2010.
6. NOAA National Climatic Data Center. (2010, December). State of the climate: National overview for November 2010. Accessed December 15, 2010.

NASA Earth Observatory image created by Jesse Allen, using data provided courtesy of the NASA/GSFC Distributed Active Archive Center. Caption by Holli Riebeek.

Instrument:
Aqua - MODIS

Earth Observatory Image of the Day 17th December 2010

Dust in the Wind

Tiny solid and liquid particles—scientists refer to them as aerosols—can be found in the air all over the world, and they have a global impact on weather and climate. There are many sources of aerosols, including smoke and pollution from human activities. One of the most abundant particles is the dust and sand that blows off of Earth's deserts.

This series of images, derived from a computer model, shows wind-blown dust from North Africa as it spread over the Atlantic Ocean on July 1, 2009. The model depicts aerosol optical thickness, a measure of the amount of light that the aerosols scatter and absorb, and a proxy for the number of particles in the air. An optical thickness of less than 0.1 indicates a clear sky with maximum visibility; a value of 1 or above indicates very hazy conditions. The time signatures in the model move in six-hour increments from midnight (00:00 Universal Time, or UTC) to 6 p.m. (18:00).

Although most aerosols remain suspended in the air for just short periods—typically between four days and a week—they can travel vast distances. Particles moving with the atmosphere at 5 meters (16.4 feet) per second will travel thousands of kilometers in a week.

Dust plumes from the Sahara frequently cross the Atlantic and reach the skies of the Caribbean. Scientists are particularly interested in the role of this dust transport in the formation of clouds and in influencing the development of hurricanes and typhoons.

As noted in our fact sheet, “Aerosols: Tiny Particles, Big Impact”:

Most elementary school students learn that clouds form when enough water vapor condenses. That’s true, but aerosols play a critical role in the process. In fact, most clouds owe their existence to aerosols that serve as the tiny “seeds,” called cloud condensation nuclei. Natural aerosols are the most common condensation nuclei in pristine environments.

The event depicted above comes from the Goddard Earth Observing System Model, Version 5 (GEOS-5), an atmospheric model used to study the physics of the atmosphere in both the short term (weather) and mid- to long term (climate). The GEOS-5 model uses mathematical equations that represent physical processes—such as precipitation and cloud processes—to calculate what the atmosphere will do. Actual measurements of physical properties like temperature, moisture, and winds are routinely folded in to keep the simulation as close to the real world as possible.

The millions of calculations involved in creating such a detailed global model require thousands of computer processors. The GEOS-5 model runs on the nearly 15,000 processors of the Discover supercomputer in the new NASA Center for Climate Simulation at Goddard Space Flight Center.

NASA maps by Pete Colarco and Robert Simmon, based on GEOS-5 model data. Caption by Mike Carlowicz and Adam Voiland.

Instrument:
Model

Earth Observatory, Imge of the day 18th December 2010

Neve in arrivo su Adriatiche, Calabria e Sicilia

Anche il Sud Italia sta per assaggiare l'inverno dopo un mese di novembre generalmente con temperature sopra la media:

L'irruzione di aria gelida dai balcani e' gia' in atto da qualche giorno ed ha portato le prime nevicate, anche abbondanti sulla Turchia. Nei prossimi giorni una circolazione depressionaria interessera' anche la Grecia e le temperature molto basse favoriranno nevicate anche al livello del mare. Aspettiamoci  l'Acropoli imbiancata.

In Italia i maggiori beneficiatari di questa irruzione fredda saranno soprattutto Marchigiani, Calabresi e Siciliani che potranno contare su accumuli anche consistenti a partire da 400-600 metri con fiocchi che localmente si spingeranno anche al livello del mare specialmente sulle Marche. Di seguito la precipitazione nevosa prevista dal modello curato dall' ISAC-CNR BOLAM:

Anomalie SST di novembre 2010

Il riassunto delle anomalie termiche del mese di novembre della NASA mostra ncora un mese in anomalia globalmente positiva, nonostante in giro si leggano di tanto in tanto articoli che parlano di imminenti glaciazioni; si notano però anomalie negative localizzate sull'Australia e l'Europa, specie settentrionale ed occidentale, che sicuramente ci hanno dato l'illusione di un ritorno verso il f...reddo (anche se sull'Italia il mese, pur con la bassa risoluzione fornita, sembra circa in media).

Tornado d'epoca con Machiavelli

Spesso si sente dire che determinati fenomeni, nel nostro Paese, sono frutto solo del mutamento climatico; in particolare, ogni volta che si verifica una vera tromba d'aria, si punta il dito contro la tropicalizzazione del clima alle nostre latitudini. La dimostrazione che i tornado esistono da tempo non è difficile da trovare, già Lucrezio, nel De Rerum Natura, descrive il fenomeno. Particolarmente impressionante è però la cronaca di Machiavelli del tornado abbattutosi sul Centro Italia il 24 agosto 1456. Ecco il testo:

" Ma tornando alle cose d'Italia, dico come e' correva l'anno 1456, quando i tumulti mossi da Jacopo Piccinino finirono; donde che, posate l'armi dagli uomini, parve che Iddio le volessi prendere Egli, tanta fu una tempesta di venti che allora seguì, la quale in Toscana fece inauditi per lo addietro, e a chi per lo avvenire lo intenderà, maravigliosi e memorabili effetti. Partissi a' 24 d'agosto, una ora avanti del giorno, dalle parti del mare di sopra di verso Ancona, e attraversando per la Italia entrò nel mare di sotto verso Pisa, uno turbine d'una nugolaglia grossa e folta, la quale, quasi che due miglia di spazio per ogni verso occupava. Questa, spinta da superiori forze, o naturali o soprannaturali che le fussero, in se medesimo rotta, in se medesimo combatteva; e le spezzate nugole, ora verso il cielo salendo, ora verso terra scendendo, insieme si urtavano; e ora in giro con velocità grandissima si movevano, davanti a loro uno vento fuori di ogni modo impetuoso concitavono; e spessi fuochi e lucidissimi vampi intra loro nel combattere apparivono. Da queste così rotte e confuse nebbie, da questi così furiosi venti e spessi splendori, nasceva un romore non mai più da alcuna qualità o grandezza di tremuoto o di tuono udito; dal quale usciva tanto spavento, che ciascuno che lo sentì giudicava che il fine del mondo fusse venuto, e la terra, l'acqua e il resto del cielo e del mondo, nello antico caos, mescolandosi insieme, ritornassero. Fe' questo spaventoso turbine, dovunque passò, inauditi e maravigliosi effetti: ma più notabili che altrove, intorno al castello di San Casciano seguirono. E' questo castello posto propinquo a Firenze a otto miglia, sopra il colle che parte le convalli di Pesa e di Grieve. Infra detto castello, adunque, e il borgo di Santo Andrea, posto sopra il medesimo colle, passando questa furiosa tempesta, a Santo Andrea non aggiunse, e San Casciano rasentò in modo che solo alcuni e cammini d'acune case abbaté; ma fuori, in quello spazio che è dall'uno de' luoghi detti all'altro, molte case furono infino al piano della terra rovinate. I tetti de' templi di San Martino a Bagnolo e di Santa Maria della Pace, come sopra quelli erano, furono più che un miglio discosto portati. Un vetturale, insieme con i suoi muli, fu, discosto dalla strada, nelle vicine valli trovato morto. Tutte le più grosse querce, tutti i più gagliardi arbori, che a tanto furore non volevano cedere, furono non solo sbarbati, ma discosto molto da dove avevano le loro radici portati. Onde che, passata la tempesta e venuto il giorno, gli uomini stupiti al tutto erano rimasi. Vedevasi il paese desolato e guasto: vedevasi la rovina delle case e de' templi: sentivansi i lamenti di quelli che vedevano le loro possesioni destrutte, e sotto le rovine avevano lasciato il loro bestiame e i loro parenti morti: la qual cosa a chi vedeva e udiva recava passione e spavento grandissimo. Volle sanza dubbio Iddio piuttosto minacciare che castigare la Toscana; perchè se tanta tempesta fusse entrata in una città, infra gli abitatori assai e spessi, come la entrò infra querce e arbori e case poche e rade, sanza dubbio faceva quella rovina e fragello che si può con la mente conietturare maggiore. Ma Iddio volle, per allora, che bastasse questo poco di esemplo a rinfrescare intra gli uomini la memoria della potenza sua"

La descrizione corrisponde a quella di un tornado violento, dai danni, ben descritti, si può associare una intensità pari ai gradi EF4-EF5 della scala Fujita rivisitata (http://en.wikipedia.org/wiki/Enhanced_Fujita_Scale). L'aspetto del vortice è quello con cui più spesso si presentano i tornado di questa violenza, cioè largo, frastagliato e turbolento, accompagnato dal caratteristico rumore simile a quello di un aereo in decollo, quindi chiaramente inusuale per l'epoca. Ma la particolarità più grossa di quell'episodio è sicuramente la stormtrack: Machiavelli parla infatti di un tornado approdato sulla terraferma in quel di Ancona e giunto fino in Toscana, quindi con un moto retrogrado assolutamente atipico. Al di là del fatto che sicuramente si deve essere trattato di un outbreak di diversi tornado, vista la distanza percorsa, il fenomeno doveva essere associato ad una struttura meteorologica alla mesoscala in grado di sganciarsi dal classico flusso zonale occidentale che caratterizza le nostre latitudini, presumibilmente un TLC (Tropical Like Cyclone): si tratta di minimi di pressione a cuore caldo e dotato di un occhio, proprio come i cicloni tropicali, che saltuariamente si può presentare anche nel bacino del Mediterraneo.

(fonte: http://www.tornadoit.org/index.htm)

Flavio

Tchaikovsky - The Storm, Op. 76 (Overture in E minor)

Fu ultimata da Tchaikovsky nel 1864 ma non venne ritenuta degna di pubblicazione dall'autore stesso. Si tratta del primo importante lavoro per orchestra del compositore Russo.

Interessante notare che Tchaikovsky considerava questo come un esercizio.

Direttore: Antoni Wit
Orchestra: Polish National Radio Symphony Orchestra

Manie di protagonismo della Jet Stream..

Oggi la corrente a getto non ha certo voglia di passare inosservata! S'è scavata un bel tunnel tra le nubi ad Ovest dell'Europa, ma sul Mediterraneo, dove il cielo è sostanzialmente sereno, una stretta banda di cirri ne segnala la posizione (tra l'Algeria e la Sicilia)!

Lombardia: let it snow, let it snow, let it snow!

LINK RADAR NORD-OVEST

Dopo una domenica deludente, oggi è neve sulla Lombardia! Precipitazioni anche moderate e piccola imbiancata anche nell'immediato hinterland di Milano.

Asperatus clouds?

Questa foto è stata scattata oggi da un utente del forum del Centro Meteo Lombardo; il cielo era effettivamente spettacolare verso il Milanese occidentale e la bassa Brianza. Queste nubi sono simili a quelle che lo scorso anno furono proposte dalla The Cloud Appreciation Society per una nuova classificazione di varietà... detta "Asperatus". Voi come le classifichereste? Secondo me stratocumulus stratiformis undulatus. (Flavio)