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151.
Intraseasonal variability in subtropical South America as depicted by precipitation data 总被引：1，自引：1，他引：0
Daily precipitation data from three stations in subtropical Argentina are used to describe intraseasonal variability (20–90 days) during the austral summer. This variability is compared locally and regionally with that present in outgoing longwave radiation (OLR) data, in order to evaluate the performance of this variable as a proxy for convection in the region. The influence of the intraseasonal activity of the South American Seesaw (SASS) leading convection pattern on precipitation is also explored. Results show that intraseasonal variability explains a significant portion of summer precipitation variance, with a clear maximum in the vicinity of the SASS subtropical center. Correlation analysis reveals that OLR can explain only a small portion of daily precipitation variability, implying that it does not constitute a proper proxy for precipitation on daily timescales. On intraseasonal timescales, though, OLR is able to reproduce the main features of precipitation variability. The dynamical conditions that promote the development of intraseasonal variability in the region are further analyzed for selected summers. Seasons associated with a strong intraseasonal signal in precipitation variability show distinctive wet/dry intraseasonal periods in daily raw data, and are associated with a well defined SASS-like spatial pattern of convection. During these summers, strong large-scale forcing (such as warm El Niño/Southern Oscillation (ENSO) events and/or tropical intraseasonal convective activity), and Rossby-wave-like circulation anomalies extending across the Pacific Ocean, are also observed. 相似文献
152.
Developing carbon budgets for UK agriculture, land-use, land-use change and forestry out to 2022 总被引：1，自引：0，他引：1
Dominic Moran Michael MacLeod Eileen Wall Vera Eory Alistair McVittie Andrew Barnes R. M. Rees Cairistiona F. E. Topp Guillaume Pajot Robin Matthews Pete Smith Andrew Moxey 《Climatic change》2011,105(3-4):529-553
This paper derives a notional future carbon budget for UK agriculture, land use, land use change and forestry sectors (ALULUCF). The budget is based on a bottom-up marginal abatement cost curve (MACC) derived for a range of mitigation measures for specified adoption scenarios for the years 2012, 2017 and 2022. The results indicate that in 2022 around 6.36 MtCO2e could be abated at negative or zero cost. Furthermore, in the same year, over 17% of agricultural GHG emissions (7.85 MtCO2e) could be abated at a cost of less than the 2022 Shadow Price of Carbon (£34 (tCO2e)???1). The development of robust MACCs faces a range of methodological hurdles that complicate cost-effectiveness appraisal in ALULUCF relative to other sectors. Nevertheless, the current analysis provides an initial route map of efficient measures for mitigation in UK agriculture. 相似文献
153.
Vera Potop 《Theoretical and Applied Climatology》2011,105(3-4):469-483
Droughts in Moldova were evaluated using meteorological data since 1955 and a long time series (1891?C2009). In addition, yields for corn (Zea mays L.), a crop widely grown in Moldova, were used to demonstrate drought impact. The main aim is to propose use of the S i (S i-a and S i-m) drought index while discussing its potential use in studying the evolution of drought severity in Moldova. Also, a new multi-scalar drought index, the standardized precipitation?Cevapotranspiration index (SPEI), is tested for the first time in identifying drought variability in Moldova while comparing it with the commonly used standardized precipitation index (SPI). S i-m, SPI, SPEI, and S i-a indices show an increasing tendency toward more intensive and prolonged severely dry and extremely dry summer months. Drought frequency increased through six decades, which included long dry periods in the 1990s and 2000s. Moreover, the evolution of summer evapotranspiration recorded a positive and significant trend (+3.3?mm/year, R 2?=?0.46; p????0.05) between 1955 and 2009. A yield model based on the S i-a agricultural index and historic corn yields explained 43% of observed variability in corn production when drought occurred in May, July, and August. Increasing severity of the 20-year drought during the critical part of the growing season is raising corn yield losses, as net losses have so far exceeded net gains. 相似文献
154.
Dieter Stöffler Gerda Horneck Sieglinde Ott Ulrich Hornemann Charles S. Cockell Ralf Moeller Cornelia Meyer Jean-Pierre de Vera Jörg Fritz Natalia A. Artemieva 《Icarus》2007,186(2):585-588
Bacterial spores (Bacillus subtilis), cyanobacteria (Chroococcidiopsis sp.), and lichen (Xanthoria elegans) embedded in martian analogue rock (gabbro) were exposed to shock pressures between 5 and 50 GPa which is the range of pressures observed in martian meteorites. The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chroococcidiopsis sp. up to 10 GPa supports the possibility of transfer of life inside meteoroids between Mars and Earth and it implies the potential for the transfer of life from any Mars-like planet to other habitable planets in the same stellar system. 相似文献
155.
J. Urrutia‐Fucugauchi A. M. Soler‐Arechalde M. Rebolledo‐Vieyra P. Vera‐Sanchez 《Meteoritics & planetary science》2004,39(6):843-856
Abstract— Results of a detailed paleomagnetic and rock magnetic study of samples of the impact breccia sequence cored in the Yaxcopoil‐1 (Yax‐1) borehole between about 800 m and 896 m are presented. The Yax‐1 breccia sequence occurs from 794.63 m to 894.94 m and consists of redeposited melt‐rich, clast‐size sorted, fine‐grained suevites; melt‐rich, no clast‐size sorting, medium‐grained suevites; coarse suevitic melt agglomerates; coarse melt‐rich heterogeneous suevites; brecciated suevites; and coarse carbonate and silicate melt suevites. The low‐field susceptibility ranges from ?0.3 to 4018 times 10?6 SI, and the NRM intensity ranges from 0.02 mA/m up to 37510 mA/m. In general, the NRM intensity and magnetic susceptibility present wide ranges and are positively correlated, pointing to varying magnetic mineral contents and textures of the melt‐rich breccia sequence. The vectorial composition and magnetic stability of NRM were investigated by both stepwise alternating field and thermal demagnetization. In most cases, characteristic single component magnetizations are observed. Both upward and downward inclinations are present through the sequence, and we interpret the reverse magnetization as the primary component in the breccias. Both the clasts and matrix forming the breccia appear to have been subjected to a wide range of temperature/pressure conditions and show distinct rock magnetic properties. An extended interval of remanence acquisition and secondary partial or total remagnetization may explain the paleomagnetic results. 相似文献
156.
157.
158.
ABSTRACTSeveral satellite-based precipitation estimates are becoming available at a global scale, providing new possibilities for water resources modelling, particularly in data-sparse regions and developing countries. This work provides a first validation of five different satellite-based precipitation products (TRMM-3B42 v6 and v7, RFE 2.0, PERSIANN-CDR, CMORPH1.0 version 0.x) in the 1785 km2 Makhazine catchment (Morocco). Precipitation products are first compared against ground observations. Ten raingauges and four different interpolation methods (inverse distance, nearest neighbour, ordinary kriging and residual kriging with altitude) were used to compute a set of interpolated precipitation reference fields. Second, a parsimonious conceptual hydrological model is considered, with a simulation approach based on the random generation of model parameters drawn from existing parameter set libraries, to compare the different precipitation inputs. The results indicate that (1) all four interpolation methods, except the nearest neighbour approach, give similar and valid precipitation estimates at the catchment scale; (2) among the different satellite-based precipitation estimates verified, the TRMM-3B42 v7 product is the closest to observed precipitation, and (3) despite poor performance at the daily time step when used in the hydrological model, TRMM-3B42 v7 estimates are found adequate to reproduce monthly dynamics of discharge in the catchment. The results provide valuable perspectives for water resources modelling of data-scarce catchments with satellite-based rainfall data in this region.
Editor M.C. Acreman; Associate editor N. Verhoest 相似文献
159.
Roberto Pizarro Mauricio Vera Rodrigo Valdés Bridget Helwig Claudio Olivares 《水文科学杂志》2013,58(2):300-311
AbstractIn determining the possible influence of climate change, it is important to understand the temporal and spatial variability in streamflow response for diverse climate zones. Thus, the aim of this study was to determine the presence of changes in annual maximum peak flow for two climate zones in Chile over the past few decades. A general analysis, a flood frequency analysis and a trend analysis were used to study such changes between 1975 and 2008 for a semi-arid (29°S–32°S) and a temperate (36°S–38°S) climatic zone. The historic annual maxima, minima and mean flows, as well as decadal mean peak flow, were compared over the period of record. The Gumbel distribution was selected to compare the 30-year flood values of two ±15-year intervals, which showed that streamflow decreased by an average of 19.5% in the semi-arid stations and increased by an average of 22.6% in the temperate stations. The Mann-Kendall test was used to investigate the temporal changes in streamflows, with negative trends being observed in 87% of the stations analysed in the semi-arid zone, and positive trends in 57% of those analysed in the temperate zone. These differences in streamflow response between climate zones could be related to recent documented increases in altitude of the zero-degree isotherm in the Andes Mountains of Chile, since most of the significant positive and negative changes were detected in first-order rivers located closer to this mountain range.Editor D. Koutsoyiannis; Associate editor H. LinsCitation Pizarro, R., Vera, M., Valdés, R., Helwig, B., and Olivares, C., 2013. Multi-decadal variations in annual maximum peak flows in semi-arid and temperate regions of Chile. Hydrological Sciences Journal, 59 (2), 300–311. 相似文献
160.
Michael E. Böttcher Herta S. Effenberger Peer-Lennart Gehlken Georg H. Grathoff Burkhard C. Schmidt Patrizia Geprägs Rainer Bahlo Olaf Dellwig Thomas Leipe Vera Winde André Deutschmann Alexander Stark David Gallego-Torres Francisca Martinez-Ruiz 《Chemie der Erde / Geochemistry》2012,72(1):85-89
Following a tentative evidence for the occurrence of low-temperature barium manganese(II) carbonates in brackish sediments of the Baltic Sea, a stoichiometric double carbonate, BaMn[CO3]2, was synthesized from aqueous solutions at ambient temperature for the first time. Here we report the results of a multi-method approach, including scanning electron microscopy (SEM–EDX) investigations, the chemical composition, and, in particular, the diagnostic powder X-ray diffraction pattern, as well as diagnostic parts of the FT infrared absorption and Raman spectra for future identification of this new carbonate in low-temperature environments, like brackish sediments. 相似文献