Physiological responses of the seagrass Posidonia oceanica as indicators of fish farm impact     

Pérez M  García T  Invers O  Ruiz JM 《Marine pollution bulletin》2008,56(5):869-879

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Climate extremes in South Western Siberia: past and future   总被引：1，自引：1，他引：0  

Degefie T. Degefie  Elisa Fleischer  Otto Klemm  Andrey V. Soromotin  Olga V. Soromotina  Andrey V. Tolstikov  Nikolay V. Abramov 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(8):2161-2173

In this study, the temporal and spatial trends of ten climate extreme indices were computed based on observed daily precipitation and on daily maximum and minimum temperatures at 26 weather stations in South Western Siberia during the period 1969–2011 and, based on projected daily maximum and minimum temperatures, during 2021–2050. The Mann–Kendall test was employed to analyze the temporal trend and a combination of multiple linear regressions and semivariogram functions were used to evaluate the regional spatial trends and the local spatial variability of climate extremes, respectively. The results show that the temperature-based climate extremes increase at a 0.05 significance level while none of the precipitation-based climate extremes did. Spatially, dominant gradients are observed along latitude: The northern taiga vegetation zone experiences a colder and wetter climate while the southern forest steppe zone is drier and hotter. Over time, a tendency towards homogenization of the regional climate is observed through a decrease of the spatial variability for most climate extreme indices. In the future, the most intense changes are anticipated for the bio-climate indicators “growing season length” and “growing degree days” in the north, while the warming indicators, “warm day” and “warm night” are expected to be high to the south.  相似文献   

Holocene Treeline History and Climate Change Across Northern Eurasia   总被引：1，自引：0，他引：1  

Glen M. MacDonald  Andrei A. Velichko  Constantine V. Kremenetski  Olga K. Borisova  Aleksandra A. Goleva  Andrei A. Andreev  Les C. Cwynar  Richard T. Riding  Steven L. Forman  Tom W. D. Edwards  Ramon Aravena  Dan Hammarlund  Julian M. Szeicz  Valery N. Gattaulin 《Quaternary Research》2000,53(3):302

Radiocarbon-dated macrofossils are used to document Holocene treeline history across northern Russia (including Siberia). Boreal forest development in this region commenced by 10,000 yr B.P. Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia. Treeline advance on the Kola Peninsula, however, appears to have occurred later than in other regions. During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern. The development of forest and expansion of treeline likely reflects a number of complimentary environmental conditions, including heightened summer insolation, the demise of Eurasian ice sheets, reduced sea-ice cover, greater continentality with eustatically lower sea level, and extreme Arctic penetration of warm North Atlantic waters. The late Holocene retreat of Eurasian treeline coincides with declining summer insolation, cooling arctic waters, and neoglaciation.  相似文献   

利用细菌形态多样性作生态监测     

Olga M. KOZOVA  Natalya V. DUTOVA 《湖泊科学》1998,10(S1):559-561

The Institute of Biology investigations of morphological diversity of bacteriae with the aid of electronic microscopy are used for the purposes of ecological monitoring. The results obtained allow to recommend this method to be widely applied.It has been demonstrated that for oligotrophic lake Baikal microflora consists mainly from ultra-microscopic cocci. Where the river Selenga inflows into Baikal morphological diversity of bacteriae is much wider. Bacterioplankton of Irkutsk reservoir by morphological characteristics is very similar to one of lake Baikal In meso-eutrophic Bratsh reservoir bacteriuplankton is more morphologically diversified. There are flexibacteriae, vibrios. Caulobacter sp. cells occurring in its water body.In the places of waste waters'' income to river. Angara morphological diversity of bacteriae is high and various forms with projections etc. can be observed.  相似文献   

Barriers to progress in distributed hydrological modelling          下载免费PDF全文

Olga Semenova  Keith Beven 《水文研究》2015,29(8):2074-2078

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Surface Stokes drift in the Baltic Sea based on modelled wave spectra     

Laura Tuomi  Olga Vähä-Piikkiö  Pekka Alenius  Jan-Victor Björkqvist  Kimmo K. Kahma 《Ocean Dynamics》2018,68(1):17-33

The Stokes drift is an important component in the surface drift. We used the wave model WAM to evaluate the mean values and exceedance probabilities of the surface Stokes drift in the Baltic Sea. As there is no direct way to verify the accuracy of the modelled Stokes drift, we compared the bulk parameters calculated by the wave model against buoy measurements to ensure the quality of the wave hindcast. Furthermore, we evaluated the surface Stokes drift from measured wave spectra to assess the accuracy of the modelled surface Stokes drift. The importance of the Stokes drift as a component of the total surface drift was evaluated by calculating the hindcast mean values and percentiles of the surface Stokes drift. The mean values were between 0.08 and 0.10 ms^?1 in the open sea areas, thus being of the same order of magnitude as the mean wind shear currents. The highest values of the surface Stokes drift were slightly larger than 0.6 ms^?1. The comparison of modelled Stokes drift values to estimates obtained from measured spectra suggests that the mean values are well represented by the model. However, the higher modelled values are most likely slightly too large because the wave energy was overestimated during high wind situations in some of the sub-basins, such as the Gulf of Finland. A comparison to a drifter experiment showed that use of the Stokes drift improves the estimate of both the drift speed and the direction in the Gulf of Finland. Parameterised methods to evaluate the Stokes drift that are used, e.g. in currently available Baltic Sea drift models, overestimate the smaller values (under 0.3 ms^?1) and underestimate the larger values of the Stokes drift compared to the values calculated by the wave model. The modelled surface Stokes drift direction mostly followed the forcing wind direction. This was the case even in the Gulf of Finland, where the direction of the wind and the waves can differ considerably.  相似文献   

Threshold level approach for streamflow drought analysis in the Central Andes of Argentina: a climatological assessment     

Juan A. Rivera  Diego C. Araneo  Olga C. Penalba 《水文科学杂志》2017,62(12):1949-1964

A streamflow drought climatology was developed over the Central Andes of Argentina, a semi-arid region highly vulnerable to climatic variations, based on the analysis of daily historical streamflow records. A threshold level approach was applied on a daily basis for three different severity levels in order to depict the main characteristics of droughts – number of drought events, mean duration and mean severity – over the period 1957–2014. Based on three annual indices that summarize the frequency of drought events, their duration and severity, we identified the main regional dry periods and the main modes of variability through an empirical decomposition. These modes are linked to La Niña conditions on inter-annual time scales and the Pacific Decadal Oscillation for the decadal variations, showing the influence of the tropical Pacific Ocean in the development of streamflow drought conditions and its relevance for potential predictability of hydroclimatic variations over the region.  相似文献   

Weather noise impact on the uncertainty of simulated water balance components of river basins     

Yeugeniy M. Gusev  Vladimir A. Semenov  Olga N. Nasonova  Evgeny E. Kovalev 《水文科学杂志》2017,62(8):1181-1199

Assessments of hydrological response to climatic changes are characterized by different types of uncertainties. Here, the uncertainty caused by weather noise associated with the chaotic character of atmospheric processes is considered. A technique for estimating such uncertainty in simulated water balance components based on application of the land surface model SWAP and the climate model ECHAM5 is described. The technique is applied for estimating the uncertainties in the simulated water balance components (precipitation, river runoff and evapotranspiration) of some northern river basins of Russia. It is shown that the larger the area of a basin the less the uncertainty. This dependency is smoothed by differences in natural conditions of the basins. Analysis of the spectral densities of water balance components shows that a river basin filters out high-frequency harmonics of spectral density of precipitation (corresponding to synoptic or sub-seasonal scale) during its transformation into evapotranspiration and especially into runoff.