Volando en la grieta de un glaciar/Flying through a crack in the ice

El glaciar Pine Island es una corriente de hielo que fluye en dirección oeste-noroeste a lo largo del lado sur de las montañas Hudson, desembocando en la bahía de Pine island en el Mar de Amundsen. Su superficie constituye alrededor del 10% de la capa de hielo de la Antártida occidental, y es la cuenca glaciar que más hielo aporta al mar en todo el mundo, algo que se ha incrementado en los últimos años debido a la aceleración del flujo de hielo.
En octubre de 2011 los investigadores de la NASA participantes en la operación IceBridge llevaron a cabo, en dicho glaciar, las primeras medidas aéreas del nacimiento de un gran iceberg (iceberg calving) mientras se producía el evento. La grieta producida en la capa de hielo tiene más de 30 km de largo, una anchura media de 80 metros y una anchura máxima de 250 metros. El cañón tiene una profundidad entre 50 y 60 metros  y el fondo está más o menos al nivel del agua en el mar de Amundsen. El espesor de la capa de hielo parece ser de 500 metros, de los que solo entre 50 y 60 metros sobresalen del agua, estando el resto sumergido.
Los científicos esperan que la grieta se propague a través del resto de la capa de hielo liberando un iceberg que podría tener una superficie de hasta 900 kilómetros cuadrados. No obstante, si esto no se produce pronto, el invierno austral hará que el mar se hiele de nuevo, soldando el trozo de hielo contra la costa por más tiempo.
La imagen de arriba es una instantánea tomada de un vuelo virtual a través de la grieta del glaciar Pine Island, y pertenece al siguiente video sido montado a partir de los datos tomados por los científicos de la NASA

Pine Island Glacier  is a large ice stream flowing west-northwest along the south side of the Hudson Mountains into Pine Island Bay, Amundsen Sea, Antarctica. The area drained by Pine Island Glacier comprises about 10 percent of the West Antarctic Ice Shee, and has the greater net contribution of ice to the sea than any other ice drainage basin in the world, a fact increased due to recent acceleration of the ice stream.
In October 2011, researchers flying in NASA’s Operation IceBridge campaign made, in that glacier, the first-ever detailed, airborne measurements of a major iceberg calving event while it was in progress. The rift formed in an ice shelf extends from more than 30 km (18 miles) in length, an average width of 240 feet (about 80 meters) and was 820 feet (250 meters) at its widest. The canyon ranged from 165 to 190 feet deep (50 to 60 meters), with the floor being roughly at the water line of the Amundsen Sea. Radar measurements suggested the ice shelf is about 1,640 feet (500 meters) feet thick, with only 165 to 190 feet of that floating above water and the rest submerged.
Scientists have been waiting for the crack to propagate through the rest of the ice shelf and release an iceberg, which they estimate could span 300 to 350 square miles (up to 900 square kilometers). If it does not split off soon, however, the sea ice that forms with the onset of southern winter might keep the ice chunk trapped against the coast for a while.
The above image is a still frame captured from a three-dimensional, virtual flight through the new rift in the Pine Island Glacier, created from the data acquired by the NASA's scientists.

Tomado de/Taken from NASA

A los fans de la Guerra de las Galaxias, el vuelo virtual por la grieta del glaciar les recordará el vuelo a través de la trinchera de la Estrella de la Muerte. ¡Disfrutad de las diferencias y similitudes entre la realidad y la ficción!

To the fans of the 'Star Wars' saga the virtual flight above the rift will seem very similar to the fly through the trench in the Death Star. Enjoy the differences and similarities between reality and fiction!

Tucanes con GPS ayudan a estudiar la dispersión de las semillas/Toucans Wearing GPS Help to Study Seed Dispersal

El éxito reproductivo de cualquier frutal depende de la eficacia de la dispersión de sus semillas , pero el seguimiento y mapeado de las semillas individuales llevadas por el viento o ingeridas por los animales es casi imposible. Hoy, por hoy los ecólogos que estudian la dinámica del bosque confían sobre todo en modelos teóricos para determinar el área de distribución de semillas para plantas específicas. Las nuevas tecnologías de seguimiento están cambiando eso.
En la primera fase de un experimento llevado a cabo por científicos del Smithsonian Tropical Research Institute de Panamá , se recogieron semillas frescas de un árbol de nuez moscada común panameño (Virola nobilis) on las que se alimentó a tucanes (Ramphastos sulfuratus) cautivos del zoológico de Rotterdam. El tucán se traga entera la semilla de nuez moscada: la pulpa externa es digerida mientras que la pepita interna es regurgitada. Cinco tucanes del zoológico que se comieron 100 semillas de nuez moscada tardaron una media de 25.5 minutos para procesar y regurgitar las pepitas.
Después, en Panamá, los científicos capturaron seis tucanes salvajes ( cuatro R. sulfuratus y dos R. swainsonii) que se alimentaban de un enorme árbol de nuez moscada en la selva tropical de Gamboa. Les colocaron mochilas ligeras que contenían dispositivos GPS (que registraban la localización exacta del pájaro cada 15 minutos) y con acelerómetros que pueden medir la actividad diaria de las aves.
Al comparar con el tiempo medio de regurgitación de los tucanes del zoo, los datos GPS indicaron que los tucanes salvajes regurgitaban las pepitas una distancia media de 155 m del árbol madre. Cada semilla tenía un 56% de probabilidades de ser regurgitada como mínimo a 100 m del árbol y un 18% de serlo a 215 m
Además, el acelerómetro reveló que el pico de actividad y movimiento de los tucanes se producía por la mañana con un descanso a mediodía. un pico secundario de actividad por la tarde, e inactividad completa en la noche. Este es un patrón normal para los pájaros tropicales.
Según los científicos: “ La hora de la alimentación tenía una fuerte influencia en la dispersión de la semilla, Las semillas injgridas por la mañana (desayuno) y por la tarde (cena) tenían más probabilidad de ser dispersadas significativamente que las ingeridas al mediodía (almuerzo)."
Esta observación explica porqué los árboles de nuez moscada tropicales son "especialistas de la madrugada” y dan frutos que maduran a la madrugada y a la media mañana de manera que sean fácilmente ingeridos por los pájaros”.
El video corresponde a la canción 'El Tucán' del grupo español Esclarecidos

The reproductive success of any fruiting plant depends upon how effectively its seeds are dispersed, yet tracking and mapping individual seeds carried off by the wind or ingested by animals is nearly impossible. Today, ecologists studying forest dynamics rely mostly on theoretical models to calculate the area of seed distribution for specific plants. New tracking technology is changing that.
During the first stages of an experiment carried out by scientists at the Smithsonian Tropical Research Institute in Panama, fresh seeds from a common Panamanian nutmeg tree (Virola nobilis) were collected and fed them to captive toucans (Ramphastos sulfuratus) at the Rotterdam Zoo. Toucans gulp nutmeg seeds whole, the outer pulp is processed in the bird's crop, and the hard inner seed is then regurgitated. Five zoo toucans fed 100 nutmeg seeds took an average of 25.5 minutes to process and regurgitate the seeds.
Next, in Panama, the scientists netted six wild toucans (four R. sulfuratus and two R. swainsonii) that were feeding from a large nutmeg tree in the rainforest at Gamboa. They fitted the birds with lightweight backpacks containing GPS tracking devices (these devices recorded the birds' exact location every 15 minutes) and accelerometers which can measure a bird's daily activity level.
When matched with the seed-regurgitation time of the zoo toucans, the GPS data indicated the wild toucans were probably dropping nutmeg seeds a distance of 472 feet, on average, from the mother tree. Each seed had a 56 percent probability of being dropped at least 328 feet from its mother tree and an 18 percent chance of being dropped some 656 feet from the tree.
In addition, the accelerometer revealed that the toucans' peak activity and movement was in the morning followed by a lull at midday, a secondary activity peak in the afternoon, and complete inactivity at night. This is a normal pattern of tropical birds.
"Time of feeding had a strong influence on seed dispersal," the scientists write. "Seeds ingested in morning (breakfast) and afternoon (dinner) were more likely to achieve significant dispersal than seeds ingested mid-day (lunch)."
This observation explains why tropical nutmegs are "early morning specialists" with fruits that typically ripen at early and mid-morning so they are quickly removed by birds.
The video is the song 'El Tucán (The Toucan)' by the spanish band 'Esclarecidos'

Tomado de/Taken from Science daily

Resumen de la publicación/Abstract of the paper
The effect of feeding time on dispersal of Virola seeds by toucans determined from GPS tracking and accelerometers
Roland Kaysa, Patrick A. Jansenb,Elise M.H. Knechtc, Reinhard Vohwinkele and Martin Wikelskib
Acta Oecologica http://dx.doi.org/10.1016/j.actao.2011.06.007
Abstract
Seed dispersal is critical to understanding forest dynamics but is hard to study because tracking seeds is difficult. Even for the best-studied dispersal system of the Neotropics, Virola nobilis, the dispersal kernel remains unknown. We combined high-resolution GPS/3D-acceleration bird tracking, seed-retention experiments, and field observations to quantify dispersal of V. nobilis by their principal dispersers, Ramphastos toucans. We inferred feeding events from movement data, and then estimated spatio-temporally explicit seed-dispersal kernels. Wild toucans moved an average of 1.8 km d−1 with two distinct activity peaks. Seed retention time in captive toucans averaged 25.5 min (range 4–98 min). Estimated seed dispersal distance averaged 144 ± 147 m, with a 56% likelihood of dispersal >100 m, two times further than the behaviour-naive estimate from the same data. Dispersal was furthest for seeds ingested in the morning, and increased with seed retention time, but only up to 60 min after feeding. Our study supports the long-standing hypothesis that toucans are excellent dispersers of Virola seeds. To maximize seed dispersal distances trees should ripen fruit in the morning when birds move the most, and produce fruits with gut-processing times around 60 min. Our study demonstrates how new tracking technology can yield nuanced seed dispersal kernels for animals that cannot be directly observed

Predicen ciclones mediterráneos de forma rápida y barata/ Simple and fast prediction of Mediterranean cyclones

Científicos de la Universidad de Islas Baleares han desarrollado una nueva metodología para mejorar la predicción entre 48 y 24 horas antes de los ciclones que ocurren en el Mar Mediterráneo. Los investigadores han aplicado un cálculo estadístico de sensibilidades de la atmósfera real para predecir los ciclones desde una perspectiva climatológica precisa y de bajo coste.

La región mediterránea es una área de ciclones muy activa que con frecuencia se ve afectada por estos fenómenos atmosféricos severos que producen vientos fuertes y lluvias intensas. Aunque la comunidad científica se esfuerza en mejorar la predicción numérica de los ciclones, los sistemas habituales siguen siendo costosos. Los estudios de sensibilidad son una propuesta de bajo coste y eficiente para determinar las estrategias de observación óptimas.

Con este método, los científicos son capaces de mejorar la predicción de la evolución y el impacto de los ciclones entre 48 y 24 horas antes de su formación completa. La temperatura y la velocidad del viento son factores importantes para la predicción del fenómeno.

Según Garcies y Homar del Grupo de Meteorología de la Universidad de las Islas Baleares (UIB) , "los resultados para ciclones mediterráneos intensos muestran coherencia dinámica, espacial y temporal de los campos de sensibilidad, y pueden competir con resultados análogos obtenidos con técnicas mucho más costosas”,

Scientists of the University of the Balearic Islands have developed a new methodology to improve the prediction between 48 and 24 hours before the apparition of the cyclones that happen in the Mediterranean Sea. The researchers have applied a statistical calculation of sensitivities of the real atmosphere to predict cyclones from a low cost and precise climatologic perspective.

The Mediterranean region is a very active cyclone area frequently affected by these severe atmospherics phenomena, that produce strong winds and intense rains. Although the scientific community strives in improving the numerical prediction of cyclones, the habitual systems continue being expensive. The sensitivity studies are a efficient and low-cost proposal to determine the optimal strategies of observation.

With this method, the scientists will be able to improve the prediction of the evolution and the impact of cyclones between 48 and 24 hours before their complete formation. The temperature and the wind speed are important factors for the prediction of the phenomenon.

According to Garcies and Homar from the Metereology Research Group of the University of Balearic Islands (UIB) , “the results for intense Mediterranean cyclones show dynamic, space and temporal coherence of the sensitivity fields, and are coherent with analogous results found by using much more expensive techniques"

Tomado de/ Taken from Plataforma SINC

Resumen de la publicación/ Abstract of the paper
L. GARCIES and V. HOMAR, Ensemble sensitivities of the real atmosphere: application to Mediterranean intense cyclones, Tellus Series A- Dynamic Meteorology and Oceanography, 61(3) : 394-406 (2009. )
DOI 10.1111/j.1600-0870.2009.00392.x

ABSTRACT
Ensemble sensitivity has been recently proposed as an alternative cheap approach to sensitivity analysis. We adapt it to compute climatological sensitivity estimates of intense Mediterranean cyclones using a climatology based of the ECMWF ERA-40 fields. A catalogue of 1202 events, objectively detected and classified in 25 clusters, is used in this study. Sensitivity fields are derived for each intense Mediterranean cyclone type by correlating the precursor conditions with the mature cyclones depths. Corrections to the raw sensitivity estimates are applied by means of the correlation coefficient. Further, a normalization based on the climatological spatial variability of the variance of the precursor conditions is used to derive the final sensitivity fields. The 24 h sensitivity information derived for each intense Mediterranean cyclone type is easily interpretable both in amplitude and distribution. A synthetic result combining the sensitivity fields for all 25 intense Mediterranean cyclone classes shows that the evolution of these high-impact systems 24 h prior to its maturity stage depends largely on structures located over Western Europe, the Northern African lands and parts of east North Atlantic. These results are in agreement and complement with previous results obtained with the expensive adjoint model, although further work is needed to objectively verify the results.

Un método sencillo para predecir las crecidas del Ebro/Simple method to predict Ebro River level rises

Un equipo de investigadores de la Universidad de Castilla-La Mancha (UCLM) ha desarrollado un nuevo modelo matemático que permite predecir de forma sencilla las crecidas del río Ebro en Zaragoza a partir del flujo de agua que se registra en Castejón (Navarra). En una predicción a 20 horas, el sistema acierta el 97,5% de los casos.
El estudio, que se publicará en abril en la revista Environmental Modelling & Software, aborda el problema de cómo modelizar y predecir los flujos y niveles del Ebro en la capital aragonesa, a partir del análisis de un tramo de 110 km que comienza en la localidad navarra de Castejón.
Los investigadores han desarrollado el sistema predictivo en dos etapas. Primero han utilizado una función matemática“de transferencia” para dimensionar el modelo e identificar de forma aproximada el retardo con el que el flujo del agua en Castejón afecta al nivel de las aguas en Zaragoza.
“Pero la dinámica del río no se comporta de forma lineal”, apunta Pedregal. El profesor señala, por ejemplo, que el agua circula más rápido cuando el caudal es medio o bajo, que las tormentas no afectan por igual a un lecho seco (absorbe más el agua) que a uno húmedo, o que los deshielos rápidos arrastran un aguanieve que se comporta de forma diferente al agua líquida.
Todos estos factores, además de la propia física de los fluidos, hacen que la dinámica de los ríos sea “no lineal”, por lo que los investigadores han aplicado sistemas matemáticos de este tipo y han propuesto un algoritmo específico que recoja la influencia de las variables.
La capacidad predictiva del modelo se ha contrastado con la información de la base de datos histórica de la Confederación Hidrográfica del Ebro, produciendo unos errores medios del 2,5% en un horizonte de predicción de 20 horas.

A team of researchers from the University of Castilla-La Mancha (UCLM) has developed a new mathematical method to easily predict rises in the level of the Ebro River in Zaragoza based on water flow recorded in Castejón (Navarre). The system has a 97.5% success rate for 20-hour predictions.
The study, to be published in April in the journal Environmental Modelling & Software, looks at the problem of how to model and predict the flow and levels of the Ebro in the regional capital of Aragon, based on analysis of a 110km section that starts in the town of Castejón, in Navarre.
The researchers developed the predictive system in two stages. First of all they used a mathematical “transfer” function to determine the scale of the model and get an approximate idea of the time delay before the water flowing through Castejón has an impact on water levels in Zaragoza.
“But the river’s dynamics don’t behave in a linear way,” points out Pedregal: the water flows more quickly when it is at an average or low level, that storms do not have the same effect on a dry river bed (which absorbs more water) as a wet one, and that rapid thawing of snow introduces slushy water into the river, which behaves in a different way than liquid water.
All these factors, along with the physics of fluid itself, means that the dynamics of rivers are “not linear”, resulting in the researchers having had to use mathematical systems to reflect these factors and produce a specific algorithm to incorporate the impact of all these variables.
The predictive ability of the model has been contrasted with information from the historical database of the Hydrographic Confederation of the Ebro River, resulting in an average error rate of 2.5% over a 20-hour prediction timescale.

Tomado de/Taken from Plataforma SINC/Science Daily

Resumen de la publicación/Abstract of the paper
D.J. Pedregal, R. Rivas, V. Feliu, L. Sánchez y A. Linares. A non-linear forecasting system for the Ebro River at Zaragoza, Spain. Environmental Modelling & Software, 2009; 24 (4): 502
Abstract
This paper addresses the problem of modelling and forecasting river flows and levels based on flood routing type models. Though this is generally considered as a non-linear problem, very often it is treated by linear models. A forecasting system is built for the level and flow measurements registered in the Ebro River at the station of Zaragoza (Spain), with the main purpose of preventing floods in an early stage of development. The model takes advantage of the wealth of data available at the Ebro Hydrographical Confederation and is non-linear in essence. The system is obtained by application of system identification tools, starting from a linear specification and relating the parameters of the model estimated to some transformation of the input in the system. Such transformation requires the application of a Kalman Filter in a particular set up and the full estimation algorithm involves an iterative procedure. The model is fully developed on a data set and is thoroughly validated on a different span of data