Щодо питання про територіальні межі та назву земель середнього Подніпров'я

The expansion of OMZs (Oxygen Minimum Zones) due to climate change and their possible evolution and impacts on the ecosystems and the atmosphere are still debated, mostly because of the unability of global climate models to adequatly reproduce the processes governing OMZs. In this study, we examine the factors controlling the oxygen budget, i.e. the equilibrium between oxygen sources and sinks in the northern Arabian Sea OMZ using an eddy-resolving biophysical model. Our model confirms that the biological consumption of oxygen is most intense below the region of highest productivity in the western Arabian Sea. The oxygen drawdown in this region is counterbalanced by the large supply of oxygenated waters originated from the south and advected horizontally by the western boundary current. Although the biological sink and the dynamical sources of oxygen compensate on annual average, we find that the seasonality of the dynamical transport of oxygen is 3 to 5 times larger than the seasonality of the biological sink. In agreement with previous findings, the resulting seasonality of oxygen concentration in the OMZ is relatively weak, with a variability of the order of 15% of the annual mean oxygen concentration in the oxycline and 5% elsewhere. This seasonality primarily arises from the vertical displacement of the OMZ forced by the monsoonal reversal of Ekman pumping across the basin. In coastal areas, the oxygen concentration is also modulated seasonally by lateral advection. Along the western coast of the Arabian Sea, the Somali Current transports oxygen-rich waters originated from the south during summer and oxygen-poor waters from the northeast during winter. Along the eastern coast of the Arabian Sea, we find that the main contributor to lateral advection in the OMZ is the Indian coastal undercurrent that advects southern oxygenated waters during summer and northern low-oxygen waters during winter. In this region, our model indicates that oxygen concentrations are modulated seasonally by coastal Kelvin waves and westward-propagating Rossby waves. Whereas on seasonal time scales the sources and sinks of oxygen are dominated by the mean vertical and lateral advection (Ekman pumping and monsoonal currents), on annual time scales we find that the biological sink is counterbalanced by the supply of oxygen sustained by mesoscale structures (eddies and filaments). Eddy-driven advection hence promotes the vertical supply of oxygen along the western coast of the Arabian Sea and the lateral transport of ventilated waters offshore the coast of Oman and southwest India

10. Impacto del cambio climático sobre el mar peruano: tendencias actuales y futuras

El Sistema de la Corriente de Humboldt es uno de los ecosistemas de producción de peces más eficientes del mundo gracias a la abundancia de fitoplancton que aflora con aguas frías y ricas en nutrientes hacia las capas iluminadas superficiales del océano. Se ha observado que la temperatura de la capa superficial del mar muestra un enfriamiento desde hace más de 150 años, lo cual sería favorable al ecosistema. Las investigaciones actuales buscan entender si la tendencia de enfriamiento observada en la segunda parte del siglo 20 es natural o forzada por el cambio climático. También buscan elaborar diferentes escenarios posibles de cambio climático futuro y sus impactos sobre el ecosistema de afloramiento costero del Perú y sus recursos pesqueros. Para obtener proyecciones más acertadas, los modelos utilizados actualmente para simular cambios regionales futuros deben mejorar la integración de varios efectos, tanto físicos como bioquímicos (como los vientos costeros y la desoxigenación) y tener una resolución espacial más fina para representar mejor los procesos costeros en las zonas claves del afloramiento.Le système du Courant de Humboldt est l’un des écosystèmes de production de poissons parmi les plus efficaces au monde grâce à l’abondance de phytoplancton qui affleure dans les eaux froides et riches en nutriments des couches superficielles illuminées de l’océan. Un refroidissement de la couche superficielle de l’océan depuis plus de 150 ans a été observé, lequel serait favorable à l’écosystème. Les recherches actuelles cherchent à comprendre si la tendance au refroidissement observée dans la deuxième moitié du 20ème siècle est naturelle ou forcée par le changement climatique. Elles cherchent également á élaborer différents scénarios de changement climatique futur et ses impacts sur les écosystèmes d’affleurement côtier au Pérou et les ressources halieutiques. Pour obtenir des projections plus justes, les modèles utilisés actuellement pour simuler les changements régionaux futurs doivent améliorer l’intégration de plusieurs facteurs, tant physiques que biochimiques (comme les vents côtiers et la désoxygénation) et avoir une résolution spatiale plus fine pour mieux représenter les processus côtiers dans les zones clé d’affleurement.The Humboldt Current ¡s one of the most efficient fish production ecosystems of the world, thanks to the abundance of phytoplankton that surfaces with cold water and rich nutrients to the illuminated surface of the ocean. It has been observed that the temperature of the sea surface shows cooling for more than 150 years ago, which would be favorable the ecosystem. Current research seeks to understand whether the cooling trend observed in the second half of the 20th century is natural or torced by climate change. They also seek to develop possible future scenarios of climate change impacts on the Coastal ecosystem of Peru and its fishery resources. For more accurate projections, models currently used to simulate future regional changes should improve the integration of various effects, both physical and biochemical (such as Coastal winds and deoxygenation), and have a finer spatial resolution to better represent Coastal processes in key areas of outcrop

Variational analysis of drifter positions and model outputs for the reconstruction of surface currents in the central Adriatic during fall 2002

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C04004, doi:10.1029/2007JC004148.In this paper we present an application of a variational method for the reconstruction of the velocity field in a coastal flow in the central Adriatic Sea, using in situ data from surface drifters and outputs from the ROMS circulation model. The variational approach, previously developed and tested for mesoscale open ocean flows, has been improved and adapted to account for inhomogeneities on boundary current dynamics over complex bathymetry and coastline and for weak Lagrangian persistence in coastal flows. The velocity reconstruction is performed using nine drifter trajectories over 45 d, and a hierarchy of indirect tests is introduced to evaluate the results as the real ocean state is not known. For internal consistency and impact of the analysis, three diagnostics characterizing the particle prediction and transport, in terms of residence times in various zones and export rates from the boundary current toward the interior, show that the reconstruction is quite effective. A qualitative comparison with sea color data from the MODIS satellite images shows that the reconstruction significantly improves the description of the boundary current with respect to the ROMS model first guess, capturing its main features and its exchanges with the interior when sampled by the drifters.Four of the authors are supported by the Office of Naval Research, V.T. and A.G. under grants N00014-05-1-0094 and N00014-05-1-0095, P.M.P. under grant N00014-03-1-0291, and S.C. under grant N00014-05-1-0730. CNR-ISMAR activity was partially supported by P.O.R. ‘‘CAINO’’ (Regione Puglia), VECTOR (Italian MIUR) project, and ECOOP (EU project)

Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

The Peruvian upwelling system encompasses the most intense and shallowest oxygen minimum zone (OMZ) in the ocean. This system shows pronounced submesoscale activity like filaments and fronts. We carried out glider-based observations off Peru during austral summer 2013 to investigate whether submesoscale frontal processes ventilate the Peruvian OMZ. We present observational evidence for the subduction of highly oxygenated surface water in a submesoscale cold filament. The subduction event ventilates the oxycline but does not reach OMZ core waters. In a regional submesoscale-permitting model we study the pathways of newly upwelled water. About 50% of upwelled virtual floats are subducted below the mixed layer within 5 days emphasizing a hitherto unrecognized importance of subduction for the ventilation of the Peruvian oxycline