Theoretical and Applied Climatology - Gridded precipitation products from remote sensing are currently available and could potentially enhance the use of precipitation data in regions with sparse... 相似文献
The relationship of the hydrological variability of the Rio Negro in Manaus and the dominant large-scale climate variability patterns for the 1902–2007 period is investigated using the quantile method and composite analyses. Variations of the Rio Negro Level (RNL) during its 3-month high (May to July—MJJ) and low (October to December—OND) phases are examined separately. The El Niño (La Niña) related maximum warming (cooling) in the central tropical Pacific during its mature and decaying stages modulates the atmospheric circulation in the tropics and displaces the Walker circulation cell eastward (westward), so that its sinking (rising) branch occurs over western Amazon and causes negative (positive) precipitation anomalies in this region. These anomalous climate conditions occur before the Rio Negro high phase (MJJ) and contribute to reduce (increase) the RNL and lead to a very low (very high) event in the river. On the other hand, the SST variability modes in the tropical Atlantic mainly during the transition from wet to dry season modulate the precipitation variations over western Amazon in OND. The very high events are more frequent after the 1960’s decade and the very low events, before the 1930’s decade. Therefore, the occurrence of these events contains a multidecadal scale variability. The results also indicate that the variations in the rainfall in western Amazon occur up to 9 months in advance and modulate the RNL in Manaus. The results presented here might be useful for monitoring purposes of the RNL.
This study attempts to reconstruct the rainfall conditions of southern Spain from 1600 A.D. to 1650 A.D. during the so-called Little Ice Age. Weather information was taken from original documentary sources (urban annals, local and religious histories, municipal documents, letters) in two cities in the region, Seville and Granada. A numerical index was established to characterize the rainfall, its conditions, evolution and geographical distribution. Results were compared with modern precipitation data and with the results of other studies on historical climate. 相似文献
The effects of the oxygen minimum zone on the metabolism of the heterotrophic microplankton community (0.22-100 μm) in the Humboldt Current System, as well as the factors controlling its biomass production, remain unknown. Here we compare the effect of four sources of dissolved organic carbon (glucose, oxaloacetate, glycine, leucine) on microbial biomass production (such as ATP-P) and the potential enzymatic activities involved in catabolic pathways under oxic and suboxic conditions. Our results show significant differences (p < 0.05) in the ATP-P production when induced by the different substrates that are used as dissolved organic carbon herein. The induction of ATP-P production is enhanced from glucose < oxaloacetate < glycine < leucine. Nevertheless, for individual substrates, no significant differences were found between incubation under oxic and suboxic conditions except in the case of leucine. For this amino acid, the induction of ATP-P synthesis was higher under suboxic than oxic conditions. The data sets of all the substrates used showed greater potential ATP-P production under suboxic than oxic conditions. The results of the potential enzymatic activities suggest that malate dehydrogenase has the highest signal of NADH oxidization activity in the microbial assemblage. Furthermore, for all experiments, the malate dehydrogenase activity data set had a significant relationship with ATP-P production. These findings suggest that the microbial community inhabiting the oxygen minimum zone has the same or greater potential growth than the community inhabiting more oxygenated strata of the water column and that malate dehydrogenase is the activity that best represents the metabolic potential of the community. 相似文献
The reported data present the stratigraphy of several sections across a Middle-Late Jurassic Radiolaritic Unit, well exposed
in different thrust sheets pertaining to the Maghrebian chain of Southwestern Sicily. The aim was to define the chronostratigraphical
distribution of the Jurassic biosiliceous sedimentation in the Sicanian palaeogeographical zone, a deep water basin belonging
to the Southern Tethys continental margin.
The radiolarian biostratigraphy indicates that the switching from carbonate to siliceous sedimentation in the Sicanian Basin
is referable to the Bajocian, as shown by the section of Campofiorito, near Corleone. The biostratigraphical dataset allows
the correlation between the onset of biosiliceous sedimentation and the fall of biodiversity in the Sicanian basin with the
carbonate productivity crisis, indicated by the highest eutrophication that affected Western Tethys during Middle Jurassic
times.
Editorial handling: J.-P. Billon-Bruyat & M. Chiari (Guest) 相似文献
The characterization and beach morphodynamic differentiation along 620 km of Rio Grande do Sul state (RS) coastline has been principally done using beach profiles and their resulting morphometric parameters from the early 1990s through the present. The objective of the present work is to make a regional characterization, grouping the beaches with similar morphodynamic behavior along the RS coastline using multivariate statistical tools. For such purpose, a database containing topographic profiles and environment characteristics of 32 sites along the state coastline was built. A clustering analysis followed by a multidimensional scaling (MDS) analysis and an analysis of similarities (ANOSIM) was performed. The clustering and MDS results suggest that the data could be merged into six groups, one with dissipative tendencies, another with intermediate to reflective tendencies and three groups with intermediate characteristics. Each group showed distinct morphodynamic characteristics. Such differences are shown by the ANOSIM to be statistically significant. The three intermediate groups were differentiated in terms of beach mobility and percentage of medium-size sand, with higher mobility related to higher amounts of medium-size sand. The use of multivariate statistical techniques allowed a good differentiation between the RS beaches. Based on the results, it is suggested that the RS coastline can be segmented into seven different morphodynamic sectors. This approach can be used by management agencies to reduce potential oil spill impacts as well as decrease other beach hazards as well as for differentiate morphodynamical stages. 相似文献
In many circumstances, quantitative assessment of fisheries management options is either impossible due to data deficiencies or impractical given the size of the fishery. Quantitative analysis of spatial management options in particular is complicated, as information on spatial fleet and stock dynamics is often unavailable and spatial models are difficult to construct. In this paper, a qualitative framework is presented that aids in the analysis of alternative spatial management options in coastal fisheries. The framework combines expert opinion and the Analytic Hierarchy Process (AHP) to determine which options perform best taking into account the multiple objectives inherent in fisheries management. 相似文献
Stochastic methods based on time-series modeling combined with geostatistics can be useful tools to describe the variability of water-table levels in time and space and to account for uncertainty. Monitoring water-level networks can give information about the dynamic of the aquifer domain in both dimensions. Time-series modeling is an elegant way to treat monitoring data without the complexity of physical mechanistic models. Time-series model predictions can be interpolated spatially, with the spatial differences in water-table dynamics determined by the spatial variation in the system properties and the temporal variation driven by the dynamics of the inputs into the system. An integration of stochastic methods is presented, based on time-series modeling and geostatistics as a framework to predict water levels for decision making in groundwater management and land-use planning. The methodology is applied in a case study in a Guarani Aquifer System (GAS) outcrop area located in the southeastern part of Brazil. Communication of results in a clear and understandable form, via simulated scenarios, is discussed as an alternative, when translating scientific knowledge into applications of stochastic hydrogeology in large aquifers with limited monitoring network coverage like the GAS. 相似文献
The Gould Belt is the local superassociation of star formation. The age of the Belt is some few 107 yr, henceforth, its population is dominated by luminous young OB associations and low mass pre-main sequence stars. Attempts
to unveil the low mass population have been run making use of the ROSAT all-sky survey. The all sky ultraviolet survey run
by the GALaxy Evolution eXplorer (GALEX) maps several regions in the Belt. In this contribution, we present the preliminary
analysis of the UV stellar population towards the Taurus region, one of the nearest and best studied regions of star formation. 相似文献