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1.
Ponziani Michel Pogliotti Paolo Stevenin Hervé Ratto Sara Maria 《Natural Hazards》2020,104(2):1819-1839
Natural Hazards - Aosta Valley, an Alpine region in north-western Italy, has an early warning system (EWS) that issues hydrogeological alerts based on hydrological modelling and rainfall thresholds... 相似文献
2.
Massimiliano Burlando Emilia Georgieva Corrado F. Ratto 《Boundary-Layer Meteorology》2007,125(2):389-397
The planetary boundary-layer (PBL) parameterization is a key issue for the definition of initial wind flow fields in diagnostic
models. However, PBL theories usually treat separately stable, neutral, and convective stability conditions, so that their
implementation in diagnostic wind models is not straightforward. In the present paper, an attempt is made to adopt a comprehensive
PBL parameterisation, covering stable/neutral and unstable atmospheric conditions, which appears suitable to diagnostic models.
This parameterisation is implemented into our diagnostic mass-consistent code. A validation of the consistency between the
implemented PBL parameterisations has been checked through an analysis of the sensitivity of the vertical wind profiles to
atmospheric stability. 相似文献
3.
Blas Valero-Garcés Antonio Delgado-Huertas Norma Ratto Ana Navas Larry Edwards 《Journal of Paleolimnology》2000,24(3):343-359
The paleohydrological evolution of several high altitude, saline lakes located in the southernmost Altiplano (El Peinado and San Francisco basins, Catamarca province, NW Argentina) was reconstructed applying sedimentological, geochemical and isotopic techniques. Several playa lakes from the San Francisco basin (26° 56 S; 68° 08 W, 3800-3900 m a.s.l.) show evidence of a recent raise in the watertable that led to modern deposition of carbonate and diatomaceous muds. A 2 m - long core from El Peinado Lake (26° 29 59 S, 68°05 32 W, 3820 m a.s.l.) consists of calcitic crusts (unit 3), overlaid by an alternation of macrophyte-rich and travertine clast- rich, laminated muds (unit 2), and topped by travertine facies (unit 1). This sedimentary sequence illustrates a paleohydrological evolution from a subaerial exposure (unit 3) to a high lake stand (unit 2), and a subsequent smaller decrease in lake level (unit 1). The 13Corganic matterrecord also reflects the lake transgression between units 3 and 2. Although there is a general positive correlation between 18Ocarbonate and salinity proxies (Na, Li and B content), the large data dispersion indicates that other factors besides evaporation effects control chemical and isotopic composition of lakewater. Consequently, the oxygen isotopic composition cannot be interpreted exclusively as an indicator of salinity or evaporation ratio. The degassing of CO2 during groundwater discharge can explain the enriched 13C values for primary carbonates precipitated. The carbon budget in these high altitude, saline lakes seems to be controlled by physical rather than biological processes.The Altiplano saline lakes contain records of environmental and climatic change, although accurate 14C dating of these lacustrine sediments is hindered by the scarcity of terrestrial organic material, and the large reservoir effects. Sedimentologic evidence, a 210Pb-based chronology, and a preliminary U/Th chronology indicate a very large reservoir effect in El Peinado, likely as a result of old groundwaters and large contributions of volcanic and geothermal 14C-free CO2 to the lake system. Alternative chronologies are needed to place these paleorecords in a reliable chronological framework. A period of increased water balance in the San Francisco basin ended at about 1660 ± 82 yr B.P. (calendar yr U/Th age), and would correlates with the humid phase between 3000 and 1800 yr B.P detected in other sites of the southern Altiplano. Both, 210Pb and preliminary U/Th dating favor a younger age for the paleohydrological changes in El Peinado. The arid period reflected by subaerial exposure and low lake levels in unit 3 would have ended with a large increase in effective moisture during the late 17th century. The increased lake level during deposition of unit 2 would represent the period between AD1650 - 1900, synchronous to the Little Ice Age. This chronological framework is coherent with other regional records that show an abrupt transition from more arid to more humid conditions in the early 17th century, and a change to modern conditions in the late 19th century. Although there are local differences, the Little Ice Age stands as a significant climatic event in the Andean Altiplano. 相似文献
4.
P. Laiolo S. Gabellani N. Rebora R. Rudari L. Ferraris S. Ratto H. Stevenin M. Cauduro 《水文研究》2014,28(9):3466-3481
Probabilistic hydrometeorological forecasting systems are becoming more and more an operational tool used by civil protection centres for issuing flood alerts. One of the most important requests of decision makers is related to the reliability of such systems and to the validation of their predictive performances. For these reasons, this work is devoted to the validation of a probabilistic flood forecasting system called Flood‐PRObabilistic Operational Forecasting System (Flood‐PROOFS). The system is operational in real time, since 2008, in Valle d'Aosta, an alpine Region of northern Italy. It is used by the Civil Protection regional service to issue warnings and by the local water company to protect its facilities. The system manages and uses both real‐time meteorological and satellite data and real‐time data on the operation of the control structures in dam and river, managed by the water company. It has proven a useful tool for flood forecasting and for managing complex situations, facilitating the dialogue between civil protection and the water company during crisis periods. The system uses both a limited area model forecast and a forecast issued by regional expert meteorologists. The main outputs are deterministic and probabilistic discharge forecasts in different outlet areas of the river network. The performance of the system has been evaluated on a 25 months period with different statistical methods such as Brier score and Rank histograms. The results highlight good performances of the system as support system for emitting warnings, but there is a lack of statistics especially for huge discharge events. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
5.
M. Corazza A. Buzzi D. Sacchetti E. Trovatore C. F. Ratto 《Meteorology and Atmospheric Physics》2003,83(1-2):131-143
Summary ?A statistical analysis of two versions of BOLAM, a numerical model for mesoscale weather forecasting, is performed. The precipitation
patterns forecasted by the models are evaluated by means of the standard statistical indexes, using the precipitation values
observed in several stations of Liguria and Piedmont Regions (north-west of Italy) during 11 case studies occurred between
1984 and 1994. Results show a remarkable improvement of the performances of the last version of BOLAM, due to the recently
implemented features both in the dynamical and the physical schemes of the model.
Based on these results, the case study of 22–25 September 1993 (Brig flood) is simulated using integration domains of different
size, in order to verify the possible influence of lateral boundary conditions on the model performance. In particular, results
show that the use of larger domains improves the capability of the model in localizing the precipitation patterns correctly.
In addition, the case study is simulated by introducing a delay in the triggering of downdrafts in the Kain-Fritsh convective
parameterization scheme (CPS) as proposed by Spencer and Stensrud (1998). Results show improvements in the capability to forecast
heavy rain events, in particular in enhancing the precipitation amounts over the Ligurian area.
Received August 3, 2001; revised March 3, 2002 相似文献
6.
It is well known that in a neutrally-stratified turbulent flow in a deep constant-stress layer above a flat surface,the horizontal mean velocity varies logarithmically with height (the so-called `log-law-of-the-wall').More recently, the same logarithmic law has also been foundin the presence of non-flat surfaces, where it governs thedynamics of the areally-averagedvelocity and involves renormalized effective parameters.Here, we analyze wind profiles over two-dimensional sinusoidal hillsobtained both from numerical simulations performed with a primitiveequation model and from wind-tunnel measurements. We showthat also the local velocity profiles behave to a verygood approximation logarithmically, for a distance from the surface of the order of the maximum hill height almost to the top of the boundary layer. Such alocal log-law-of-the-wall involves effective parameters smoothly depending on theposition along the underlying topography.This dependence looks very similar to the topography itself. 相似文献
7.
Knowledge of frequency wind patterns is very important for air pollution modelling, especially in a city like La Plata (approximately
850,000 inhabitants) with high vehicular and industrial activities and no air monitoring network. An hourly wind analysis
was carried out on data from two local weather stations (points A and J). An initial result was that, in spite of differences
in data quality, the local weather stations observations were consistent with local and regional National Meteorological Service
(NMS) monthly based observations. Two non conventional multivariate statistical methods were employed to further analyse hourly
data at points A and J. Hierarchical cluster resulted in a good summarising tool to visualise prevailing hourly winds. Resultant
vectors emerging from the clustering process showed good similarity between sites and seasons; this allowed a further visualization
of the average diurnal wind development. Multidimensional scaling (MDS) permitted a pairwise comparison of a large number
of hourly wind roses. These wind roses were more similar to each other in colder seasons and at site A (the one that is closer
to the river) than in warmer seasons and at site J. Most of the observed variations regarding seasons and sites revealed by
cluster and MDS analysis are explained in terms of the sea-land breeze circulations. The methodology applied proved to be
of utility for simplifying the analysis of high dimensional data with numerous observations. 相似文献
8.
Palo Blanco is an approximately 1600 year old archaeological site located in Fiambalá Valley, in the Andean region of Argentina. Pioneer archaeological studies published in the 70s reported the existence of five residential units in this site. Also a small cemetery which included three circular tombs was discovered near to these buildings. Since that time, a profuse sedimentation covered the zone, so nowadays there are no evidences of most of these buildings on surface. Because of an imprecise location of the structures, most of the buildings became in fact missed. Then, in this work we aimed to re-localize two of the missed buildings, a residential unit and a tomb, by applying ground penetrating radar (GPR) methodology. We used fast fixed offset GPR configurations to investigate two areas in which these buildings could be expected. We used experimental and synthetic patterns to aid the identification of the characteristic signals due to the archaeological targets. We applied migration to the data to better define and resolve unclear anomalous signals. The employed methodology revealed the location of both buildings. Also a number of new non-reported structures were predicted and confirmed. 相似文献
9.
Massimiliano Burlando Luigi Carassale Emilia Georgieva Corrado F. Ratto Giovanni Solari 《Boundary-Layer Meteorology》2007,125(3):417-439
In spite of recent progress in the prognostic numerical simulation of the atmospheric boundary layer, the explicit simulation
of turbulent flows in actual complex terrain is generally still very complicated and time consuming for many environmental
applications. In an attempt to develop simpler and more efficient application oriented techniques, although less refined,
we propose a multi-step procedure for simulating wind fields. Once obtained the necessary meteorological input, the mass-consistent
modelling technique is used to perform high-resolution mean wind flow simulations taking into account recent developments
in the atmospheric boundary-layer theory. Besides, a procedure based on a generalisation of the local logarithmic law-of-the-wall
over complex terrain is used to estimate the effective parameters characterising the simulated wind profiles. Turbulence intensities
and spectral properties are then calculated through the estimated effective parameters, in particular through the effective
friction velocity parameter. Finally, time series of the instantaneous velocity field are simulated by the Monte Carlo technique.
Two applications of the proposed approach are discussed briefly: the first one is related to a coastal area in southern Italy
(the Messina Straits), where the construction of the world’s longest central span bridge is being planned; the second one
corresponds to the flow in a mountainous area in northern Italy (the Albenga Airport). 相似文献
10.
A unified approach to environmental systems modeling 总被引：1，自引：0，他引：1
P. C. Young Marco Ratto 《Stochastic Environmental Research and Risk Assessment (SERRA)》2009,23(7):1037-1057
The paper considers the differences between hypothetico-deductive and inductive modeling: between modelers who put their primary
trust in their scientific intuition about the nature of an environmental model and tend to produce quite complex computer
simulation models; and those who prefer to rely on the analysis of observational data to identify the simplest form of model that can represent these data. The tension that sometimes arises because of the different philosophical outlooks
of these two modeling groups can be harmful because it tends to fractionate the effort that goes into the investigation of
important environmental problems, such as global warming. In an attempt to improve this situation, the paper will outline
a new Data-Based Mechanistic (DBM) approach to modeling that tries to meld together the best aspects of these two modeling philosophies in order to develop
a unified approach that combines the hypothetico-deductive virtues of good scientific intuition and simulation modeling with
the pragmatism of inductive data-based modeling, where more objective inference from data is the primary driving force. In
particular, it demonstrates the feasibility of a new method for complex simulation model emulation, in which the methodological
tools of DBM modeling are used to develop a reduced dynamic order model that represents the ‘dominant modes’ of the complex
simulation model. In this form, the ‘dynamic emulation’ model can be compared with the DBM model obtained directly from the
analysis of real data and any tensions between the two modeling approaches may be relaxed to produce models that suit multiple
modeling objectives. 相似文献