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The stratosphere can be a source of predictability for surface weather on timescales of several weeks to months. However, the potential predictive skill gained from stratospheric variability can be limited by biases in the representation of stratospheric processes and the coupling of the stratosphere with surface climate in forecast systems. This study provides a first systematic identification of model biases in the stratosphere across a wide range of subseasonal forecast systems. It is found that many of the forecast systems considered exhibit warm global-mean temperature biases from the lower to middle stratosphere, too strong/cold wintertime polar vortices, and too cold extratropical upper-troposphere/lower-stratosphere regions. Furthermore, tropical stratospheric anomalies associated with the Quasi-Biennial Oscillation tend to decay toward each system's climatology with lead time. In the Northern Hemisphere (NH), most systems do not capture the seasonal cycle of extreme-vortex-event probabilities, with an underestimation of sudden stratospheric warming events and an overestimation of strong vortex events in January. In the Southern Hemisphere (SH), springtime interannual variability in the polar vortex is generally underestimated, but the timing of the final breakdown of the polar vortex often happens too early in many of the prediction systems. These stratospheric biases tend to be considerably worse in systems with lower model lid heights. In both hemispheres, most systems with low-top atmospheric models also consistently underestimate the upward wave driving that affects the strength of the stratospheric polar vortex. We expect that the biases identified here will help guide model development for subseasonal-to-seasonal forecast systems and further our understanding of the role of the stratosphere in predictive skill in the troposphere., Weather and Climate Dynamics Discussions, ISSN:2698-4024

24 pages, 13 figures., Las zonas polares, principales responsables del clima de nuestro planeta, están sufriendo cambios drásticos en su naturaleza debido a su alta sensibilidad al cambio global, que afectan directamente a la dinámica climática, oceanográfica y ambiental de latitudes extrapolares. El presente libro pretende dar una visión integral y multidisciplinar del estado del conocimiento de las zonas árticas y antárticas: su evolución geológica, los acuciantes problemas de contaminación de estos territorios, la caracterización de los diversos ecosistemas terrestres y marinos, así como la evolución pasada y futura del clima polar. El objetivo final es explicar, de forma clara y amena, las similitudes y diferencias entre ambos polos y concienciar sobre las alteraciones que están sufriendo debido al cambio global. Asimismo, se dan a conocer las investigaciones, de gran relevancia científica y social, realizadas por el personal científico y técnico del Consejo Superior de Investigaciones Científicas (CSIC), acercándonos a la historia y situación actual de la investigación polar en España.

Publicado en Madrid, 174 p. : 17 cm The environmental sustainability of the Earth system is at risk, and so do human welfare because of our dependency on it. Here we present challenges dealing with the understanding of how drivers of global change work, and how to minimize their effects on natural and human managed systems, with the aid of new concepts and edge-cutting technology. Their achievement should allow us to detect, understand, forecast and mitigate global change impacts related to climate change, the biodiversity crisis, polar regions, and managed ecosystems, and to improve the health of our planet in the coming decades.

18 pages, 11 figures., Las zonas polares, principales responsables del clima de nuestro planeta, están sufriendo cambios drásticos en su naturaleza debido a su alta sensibilidad al cambio global, que afectan directamente a la dinámica climática, oceanográfica y ambiental de latitudes extrapolares. El presente libro pretende dar una visión integral y multidisciplinar del estado del conocimiento de las zonas árticas y antárticas: su evolución geológica, los acuciantes problemas de contaminación de estos territorios, la caracterización de los diversos ecosistemas terrestres y marinos, así como la evolución pasada y futura del clima polar. El objetivo final es explicar, de forma clara y amena, las similitudes y diferencias entre ambos polos y concienciar sobre las alteraciones que están sufriendo debido al cambio global. Asimismo, se dan a conocer las investigaciones, de gran relevancia científica y social, realizadas por el personal científico y técnico del Consejo Superior de Investigaciones Científicas (CSIC), acercándonos a la historia y situación actual de la investigación polar en España.

The environmental sustainability of the Earth system is at risk, and so do human welfare because of our dependency on it. Here we present challenges dealing with the understanding of how drivers of global change work, and how to minimize their effects on natural and human managed systems, with the aid of new concepts and edge-cutting technology. Their achievement should allow us to detect, understand, forecast and mitigate global change impacts related to climate change, the biodiversity crisis, polar regions, and managed ecosystems, and to improve the health of our planet in the coming decades.

19 pages, 1 figure, The Arctic and the Antarctic are the regions where temperature has raised most and faster than any other Earth’s place, producing a large number of impacts and feedback to the polar/climate system. Moreover, since polar oceans play a fundamental role in the Earth’s climate and global ecosystem, those changes produce climate consequences at mid latitudes . The study and monitoring of the poles from a global perspective and holistically is fundamental to better assess and understand the changes the polar regions are facing and its consequences on ocean circulation and climate, changes on the oceanic biogeochemistry composition and consequences on the oceanic living beings. Understanding the past to infer the future is another important leg to understand how the whole system is changing. The revision of the going on transformation and the continuous monitoring can be achieved with the combination of large amounts of observations (in situ and remote sensing) and numerical models

CSIC SCIENTIFIC CHALLENGES: TOWARDS 2030, Vol. 7: GLOBAL CHANGE IMPACTS, CHALLENGE 4, The Polar Regions are key Earth’s climate regulators and, hence, any perturbation in their baseline conditions can have global repercussions. Owing their intrinsic particularities such as the presence of huge amounts of sea and continental ice, their terrestrial and marine ecosystems are highly sensitive to temperature fluctuations. In fact, both the Arctic and the Antarctic Peninsula are the regions where temperature has raised most and faster than any other Earth’s place. Moreover, other environmental issues related to anthropogenic changes such as the occurrence of contaminants, invasive species, emerging diseases and exploitation of living marine resources are also affecting the Polar Regions. Therefore, sound, detailed and long-term knowledge of the polar systems functioning, interactions and feedbacks is of paramount importance to establish and characterize the main impacts and consequences in both polar and extra-polar latitudes. Only then, efficient and environmentally friendly measures would be established both to mitigate the negative effects of current anthropogenic impacts

The purpose of this study is the characterization of the synoptic circulation patterns leading to extremely warm periods (EWPs) over the Kurdistan province of Iran. Daily maximum temperature data from 27 meteorological stations were used for the period 1962–2012. Data were interpolated to a 6 × 6 km grid using the geospatial Kriging method. EWPs were defined as a period of at least 6 consecutive days with maximum temperature above the local daily‐based 95th percentile of the 1971–2000 period, with additional criteria for spatial extension. The identified EWPs are distributed through the whole year, with maximum frequencies in winter and summer. Interestingly, the decade 1988–1997 did not record any extreme episode and summer extremes were recorded only before 1983. The associated synoptic patterns were classified into four clusters by applying the Ward's hierarchical clustering method to sea level pressure and Z500 data. Four clusters are identified: two represent warm periods in winter, one those occurring spring, especially in March, and another one mainly reflecting summer heat waves. In general, it is found that EWPs are associated with statistically significant anomalies in regional circulation. A deep trough of geopotential height in 500 hPa over North Africa and a ridge directly over the study area were the more important causes for the occurrence of EWPs. Other synoptic configurations that favour extreme periods in winter and summer include, respectively, the northward expansion of the Sudan low pressure with an associated southerly wind advection and the persistence of anticyclonic circulation at all tropospheric levels enhancing subsidence and adiabatic heating. The spring pattern is the most frequent one (nearly 48% of all cases) and reflects a southeastward extension of the subpolar low pressure that leads to the displacement of the Siberian high to south and southwestern Asia and the accompanied northward expansion of the Sudan low.

Theenvironmentalsustainability of the Earth systemisat risk, and so do human welfare because ofour dependency on it.Here we presentchallengesdealingwith the understanding of how drivers of global change work, andhow to minimize their effectson natural and human managed systems, with the aid of new concepts and edge-cutting technology. Their achievement should allow usto detect, understand, forecast and mitigate global change impacts related to climate change, the biodiversity crisis, polar regions, and managed ecosystems, and toimprove the health of our planet in the coming decades.