On the individual calibration of hailpads     

Covadonga Palencia  Claude Berthet  Marta Massot  Amaya Castro  Jean Dessens  Roberto Fraile   《Atmospheric Research》2007,83(2-4):493-504

This paper is a comparative study between the two most common hailpad calibration systems: one annual calibration of a whole consignment of material, and the individual calibration of each plate after a hailfall. Individual calibration attempts to minimize errors due to differences in sensitivity to the impact of hailstones between plates from the same consignment, or due to differences in the inking process before the actual measurement.The comparison was carried out using calibration data from the past few years in the hailpad network in south-western France, and data from an individual calibration process on material provided by the hailpad network in Lleida (Spain). The same type of material was used in the two cases.The results confirm that the error in measuring hailstone sizes is smaller in the case of an individual calibration of hailpads than when one single calibration process was carried out for a whole consignment. The former is approximately 80% of the latter. However, this error could have been higher if it had not been the same person carrying out the single calibration process and the measuring of the dents: it has been found that differences in the inking process may account for up to 20% of the error in the case of small hailstones. Calibration errors affecting other variables, e.g. energy or parameter λ of the exponential size distribution are generally higher (5% and 18%, respectively) than errors due to the spatial variability of the hailstones. However, the calibration method does not influence the maximum size, since the relative error attributed to the spatial variability is about 8 times the calibration error.In conclusion, if errors in determining energy or parameter λ are to be reduced to a minimum, it is highly advisable to be consistent in applying the measuring procedure (if possible with the same person carrying out the measurements all the time), and even to use individual calibration on each plate, always bearing in mind that technicians have to be trained appropriately in order to achieve the highest possible degree of uniformity.  相似文献   

Areal versus linear evaluation of relationship between drainage basin lithology and geochemistry of stream and overbank sediments in low-order mountainous drainage basins     

Zoran Peh  Slobodan Miko  Marta Mileusnic 《Environmental Geology》2006,49(8):1102-1115

The comparison of two multiple regression models is based on the assumption that geochemical composition of the drainage basin alluvial sediments is derived primarily from the underlying bedrock lithology. The parent material is integrated with both stream sediment and overbank sediment geochemistry via the two essentially different approaches as regards the drainage basin geomorphological data: (1) as the relative area of influence representing a portion of the catchment basin occupied by a specific rock type and (2) as the relative “line” of influence representing a narrow zone of the underlying bedrock traversed by the perennial streams which form the active stream network. The model comparison is established on the goodness-of-fit test for both experimental designs and for the same set of data. Both experiments converge on the linear approach as the more appropriate model in evaluating the lithologic influence on the analysed sample media in small mountainous watersheds.  相似文献   

Determination of the apparent copper complexing capacity of seawater by anodic stripping voltammetry     

Marta Plavšić  Damir Krznarić  Marko Branica 《Marine Chemistry》1982,11(1):17-31

A new experimental technique using differential pulse anodic stripping voltammetry with a thin-film mercury electrode and efficient mixing of the electrolyte for the apparent copper complexing capacity of seawater is proposed. The effects of some factors such as type of electrode and cell, pH of the solution, potential of deposition, time of equilibration, and influence of a non-ionic surface active agent on the measurements are examined. Experimental results for the apparent copper complexing capacity of seawater are calculated presuming 1:1 inert complex formation. By using EDTA as a model ligand, it is shown that the proposed procedure with efficient mixing of the solution excludes any appreciable kinetic influence upon the electroanalytical results.  相似文献   

Diffuse Component Spectra of Solar Active Regions at Submillimeter Wavelengths     

Adriana?V.?R.?SilvaEmail author  Tatiana?F.?Laganá  C.?Guillermo?Gimenez?De?Castro  Pierre?Kaufmann  Joaquim?E.?R.?Costa  Hugo?Levato  Marta?Rovira 《Solar physics》2005,227(2):265-281

Solar maps at 212 and 405 GHz obtained by the Solar Submillimetric Telescope (SST) show regions of enhanced brightness temperature, which coincide with the location of active regions. A statistical study of the radio emission from these active regions was performed for the first time at such high frequencies during 23 days on June and July 2002, when the atmospheric opacity was low. The brightest regions on the maps were chosen for this study, where the brightness excess observed varies from 3 to 20% above quiet Sun levels (i.e., 200–1000 K) at both wavelengths. Sizes of the regions of enhanced emission calculated at half the maximum value were estimated to be between 2′ and 7′. These sizes agree with observed sizes of active regions at other wavelengths such as Hα and ultraviolet. An important result is that the flux density spectra of all sources increase toward submillimeter frequencies, yielding flux density spectral index with an average value of 2.0. The flux density of the active region sources were complemented with that from maps at 17 and 34 GHz from the Nobeyama Radio Heliograph. The resulting spectra at all four frequencies were fit considering the flux density to be due to thermal bremsstrahlung from the active region. In the calculations, the source radius was assumed to be the mean of the measured values at 212 and 405 K. The effective temperatures of the radio emitting source, assumed homogeneous, obtained from this fit were 0.6–2.9 × 10⁴ K, for source diameters of 2′–7′.  相似文献   

Later Holocene vegetation history of the Isles of Scilly,UK: coastal influence and human land use in a small island context          下载免费PDF全文

Marta Perez  Ralph M. Fyfe  Dan J. Charman  W. Roland Gehrels 《第四纪科学杂志》2015,30(8):764-778

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‘Non‐European’ palaeomagnetic directions from the Carpathian Foredeep at the southern margin of the European plate     

Emő Márton  Antek K. Tokarski  Oldřich Krejčí  Marta Rauch  Barbara Olszewska  Pavla Tomanová Petrová  Antoni Wójcik 《地学学报》2011,23(2):134-144

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Water flow and solute transport model of potentially toxic elements through unsaturated zone at regional wellfield Kosnica          下载免费PDF全文

Stanko Ružičić  Marta Mileusnić  Kristijan Posavec  Zoran Nakić  Goran Durn  Vilim Filipović 《水文研究》2016,30(22):4113-4124

The objective of this work was to build a prognostic water flow model and potentially toxic elements (lead, cadmium, zinc) transport model in the unsaturated zone. Research was conducted in the catchment area of Kosnica regional wellfield, where the unsaturated zone is characterised by Fluvisol. Lower sorption capacities were determined in the first horizons for all three potentially toxic elements. Correlation coefficient of the measured and simulated values of tracer concentration is 0.58 for the AC horizon and 0.84 for the 2C/C1 horizon. Based on calibrated water flow and transport parameters, a prognostic water flow model and potentially toxic elements (lead, cadmium, zinc) transport model in the unsaturated zone was built. In case of an accidental spill of potentially toxic elements with concentrations of 1000 mg/l, the risk of contamination of the aquifer is present. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Climate variability and Alpine glaciers evolution in Northwestern Italy from the Little Ice Age to the 2010s     

Guido Nigrelli  Stefania Lucchesi  Stefania Bertotto  Gianfranco Fioraso  Marta Chiarle 《Theoretical and Applied Climatology》2015,122(3-4):595-608

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Present and future climatologies in the phase I CREMA experiment   总被引：1，自引：0，他引：1  

Erika Coppola  Filippo Giorgi  Francesca Raffaele  Ramon Fuentes-Franco  Graziano Giuliani  Marta LLopart-Pereira  Ashu Mamgain  Laura Mariotti  Gulilat Tefera Diro  Csaba Torma 《Climatic change》2014,125(1):23-38

We provide an overall assessment of the surface air temperature and precipitation present day (1976–2005) and future (2070–2099) ensemble climatologies in the Phase I CREMA experiment. This consists of simulations performed with different configurations (physics schemes) of the ICTP regional model RegCM4 over five CORDEX domains (Africa, Mediterranean, Central America, South America, South Asia), driven by different combinations of three global climate models (GCMs) and two greenhouse gas (GHG) representative concentration pathways (RCP8.5 and RCP4.5). The biases (1976–2005) in the driving and nested model ensembles compared to observations show a high degree of spatial variability and, when comparing GCMs and RegCM4, similar magnitudes and more similarity for precipitation than for temperature. The large scale patterns of change (2070–2099 minus 1976–2005) are broadly consistent across the GCM and RegCM4 ensembles and with previous analyses of GCM projections, indicating that the GCMs selected in the CREMA experiment are representative of the more general behavior of current GCMs. The RegCM4, however, shows a lower climate sensitivity (reduced warming) than the driving GCMs, especially when using the CLM land surface scheme. While the broad patterns of precipitation change are consistent across the GCM and RegCM4 ensembles, greater differences are found at sub-regional scales over the various domains, evidently tied to the representation of local processes. This paper serves to provide a reference view of the behavior of the CREMA ensemble, while more detailed and process-based analysis of individual domains is left to companion papers of this special issue.  相似文献   

Implementation of the European Marine Strategy Framework Directive: a methodological approach for the assessment of environmental status, from the Basque Country (Bay of Biscay)     

Borja A  Galparsoro I  Irigoien X  Iriondo A  Menchaca I  Muxika I  Pascual M  Quincoces I  Revilla M  Germán Rodríguez J  Santurtún M  Solaun O  Uriarte A  Valencia V  Zorita I 《Marine pollution bulletin》2011,62(5):889-904

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