At the national level, in Italy, observational and forecast data are collected by various public ... more At the national level, in Italy, observational and forecast data are collected by various public bodies and are often kept in various small, heterogeneous and non‐interoperable repositories, released under different licenses, thus limiting the usability for external users. In this context, MISTRAL (the Meteo Italian SupercompuTing PoRtAL) was launched as the first Italian meteorological open data portal, with the aim of promoting the reuse of meteorological data sets available at national level coverage. The MISTRAL portal provides (and archives) meteorological data from various observation networks, both public and private, and forecast data that are generated and post‐processed within the Consortium for Small‐scale Modeling‐Limited Area Model Italia (COSMO‐LAMI) agreement using high performance computing (HPC) facilities. Also incorporated is the Italy Flash Flood use case, implemented with the collaboration of European Centre for Medium‐Range Weather Forecasts (ECMWF), which exploits cutting edge advances in HPC‐based post‐processing of ensemble precipitation forecasts, for different model resolutions, and applies those to deliver novel blended‐resolution forecasts specifically for Italy. Finally, in addition to providing architectures for the acquisition and display of observational data, MISTRAL also delivers an interactive system for visualizing forecast data of different resolutions as superimposed multi‐layer maps.
Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood... more Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region - The Mesoscale Alpine Programme (MAP, the first WWRP Research and Development Project (RDP)) is an international research initiative devoted to the study of atmospheric and hydrological processes over mountainous terrain. It aims towards expanding our knowledge of weather and climate over complex topography, and thereby to improve current forecasting capabilities. A large-scale field phase in the Alpine region took place from 7 September to 15 November 1999. D-PHASE (Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) is a WWRP Forecast Demonstration Project (FDP) and aims at demonstrating some of the many achievements of MAP, in particular the ability of forecasting heavy precipitation and related flooding events in the Alpine region. The MAP FDP will address the entire forecasting chain ranging from ...
Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood... more Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region - The Mesoscale Alpine Programme (MAP, the first WWRP Research and Development Project (RDP)) is an international research initiative devoted to the study of atmospheric and hydrological processes over mountainous terrain. It aims towards expanding our knowledge of weather and climate over complex topography, and thereby to improve current forecasting capabilities. A large-scale field phase in the Alpine region took place from 7 September to 15 November 1999. D-PHASE (Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) is a WWRP Forecast Demonstration Project (FDP) and aims at demonstrating some of the many achievements of MAP, in particular the ability of forecasting heavy precipitation and related flooding events in the Alpine region. The MAP FDP will address the entire forecasting chain ranging from ...
Numerical weather prediction models (NWP) are today the best suitable tools for temperature forec... more Numerical weather prediction models (NWP) are today the best suitable tools for temperature forecast. Nevertheless, raw model output is strongly affected by systematic errors, mostly due to the rough representation of orography; such errors can be partially corrected by Model Output Statistics techniques (MOS). In this study, aiming to operate frost alerting in Trentino, both linear and nonlinear MOS algorithms are compared in predicting minimum temperature in the middle Adige Valley area. Two NWP models have been used, one Global Circulation Model (ECMWF T511 - L60) and one Local Area Model (LAMI). The following post-processing techniques have been employed: mean bias correction, multilinear regression, neural networks, random forest (RF). The latter was selected as the best performing method, and applied to the nine points (for ECMWF) and to the 21 points (LAMI) surrounding the target area. Results show that multivariate models display the best skill, but with little difference am...
W swoim artykule proponuję spojrzenie na literaturę polską w Izraelu 1 jako na literaturę "wielki... more W swoim artykule proponuję spojrzenie na literaturę polską w Izraelu 1 jako na literaturę "wielkiego przemieszczenia"-to znaczy literaturę związaną z migracjami i tworzoną przez migrantów. Niezależnie bowiem od wszelkich innych możliwych interpretacji 2 , piśmiennictwo powstające w Izraelu w językach diasporyi związane z kolejnymi falami aliji-potraktowane być może w najszerszym kulturowym ujęciu jako twórczość, która stanowi odpowiedź na doświadczenie przemieszczenia terytorialnego i związanego z nim funkcjonowania pomiędzy różnymi kulturami 3 .
The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SM... more The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on five selected members of ECMWF EPS. For the in- vestigated case studies, two different limited-area models (one hydrostatic and one non-hydrostatic) are used to generate LEPS and the forecast sensitivity to the type of limited-area model is studied for ranges between 72 and 120 hours. The attention is focused on the probabilistic prediction of total precipitation, so as to assess the possi- bility to issue flood alerts on the basis of probability maps generated by the limited- area models. Different model configurations are tested and the impact of enhanced horizontal resolution on quantitative precipitation forecast is studied. In all configura- tions, LEPS turns out to perform better than EPS to predict small scales, local severe events, thanks to the higher horizontal resolution and to the m...
Tellus A: Dynamic Meteorology and Oceanography, 2011
In this work, the main characteristics of COSMO-LEPS, the Limited-area Ensemble Prediction System... more In this work, the main characteristics of COSMO-LEPS, the Limited-area Ensemble Prediction System developed in the framework of the COnsortium for Small-scale MOdelling, are presented. The present status of the system is shown with the description of the methodology and of the main upgrades which took place during its years of activity. The performance of COSMO-LEPS for the probabilistic prediction of precipitation is assessed in terms of both time-series and seasonal scores over a 7-yr period. A fixed number of stations are selected and observations are compared to short and early medium-range forecasts. Different verification indices are used to assess the skill of COSMO-LEPS and to identify the impact of system modifications on forecast skill. The different system upgrades are found to impact positively on COSMO-LEPS performance, with a gain of 2 d of predictability in the last 4 yr of operational forecasts. This holds when the skill of the system is assessed both for single events (e.g. precipitation surpassing a fixed threshold) and for multi-event situations. Scores for fixed forecast ranges but varying thresholds confirm increasingly better performance of the system. For a few seasons, the performance of COSMO-LEPS is also assessed in terms of probabilistic prediction of some upper-air variables. Then, the skill of COSMO-LEPS is compared to that of the global-ensemble system providing the boundaries, to identify the extent to which skill improvements may relate to those of the driving ensemble. Finally, the main streams of development for COSMO-LEPS system are discussed with future possible upgrades and methodology modifications.
As commonly known, the initialisation of soil properties (temperature, moisture content and land ... more As commonly known, the initialisation of soil properties (temperature, moisture content and land coverage) can strongly affect the quantitative precipitation forecast of a numerical model, particularly in those cases in which the moisture supply is provided by local evaporation. Nevertheless, widely routine observations of soil surface properties (i.e. soil moisture content) are not available in real time. This is the reason for which we planned to use the output of a Soil-Vegetation-Atmosphere Transfer (SVAT) scheme, named LSPM (Land Surface Process Model, Cassardo et al., 1995 and 1998), to simulate soil surface temperature and moisture fields which can be also used as suitable initial conditions of a LAM integration (Balsamo et. al, 1999). The frame of the work is CLIPS (CLImatology of Parameters at the Surface) project The use of LSPM can provide realistic estimates of surface energy, thermal and hydrological budgets (Cassardo et al., 1977, and Ruti et al., 1997). Using this procedure for a long time period (several months), another goal of CLIPS experiment is to create a climatological archive of surface data on the MAP area, including also mountain stations. Precipitation Evaporation Runoff Drainage Figure 3-Components of hydrological budget cumulated on September 1995, in mm.
Presso ARPA-SIM viene utilizzato da alcuni anni il modello di previsione meterologica ad area lim... more Presso ARPA-SIM viene utilizzato da alcuni anni il modello di previsione meterologica ad area limitata Lokal Modell (LM), sviluppato inizialmente dal servizio meteorologico tedesco DWD e attualmente gestito dal Consorzio COSMO a cui partecipano, tra gli altri, vari servizi meteorologici nazionali europei. Si tratta di un modello meteorologico di ultima generazione, non idrostatico e adatto per sistemi di calcolo parallelo a memoria distribuita mediante la libreria MPI. La suite previsionale operativa di LM presso ARPA-SIM copre tutto il territorio nazionale con una griglia dal passo di 7 km circa ed effettua 2 previsioni al giorno fino a 72 ore di scadenza. Recentemente la suite operativa e stata portata su un sistema Linux/GNU installato presso ARPA-SIM, utilizzato come backup della suite principale attiva su IBM SP4 al Cineca. Il sistema, costruito con hardware comunemente disponibile e software quasi tutto open-source, comprende 44 processori Intel Xeon, interconnessi da una rete...
Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2000
ABSTRACT The development of efficient remote sensing tools, satellite and ground-based, calls for... more ABSTRACT The development of efficient remote sensing tools, satellite and ground-based, calls for an integrated use of the newly available data and NWP techniques to produce very-short-range operational forecasts. The Local Analysis and Prediction System (LAPS) has been developed by NOAA-FSL as an integrated system to ingest and analyse meteorological data from different observational sources, i.e. mesonet and regular surface data, radar and profiler data, and satellite imagery. The resulting 3-D data-set contains all relevant meteorological parameters, that is temperature, pressure, humidity, wind, clouds, and other derived variables. Radar data play a key role in accurately describing the mesoscale wind pattern, when no others observational sources are available, particularly at low level where the correlation coefficient between radar analysis vs raob analysis grew at 0.99-0.95. The resulting fields are used in a continuous assimilation cycle with a limited area model for improving the forecast skill over a meso-β domain. The overall system is presented highlighting the impact of Doppler radar data in the reconstruction of missing features and comparing the different scenarios that can be foreseen.
This paper describes an attempt to de®ne mesoscale daily precipitation and temperature regimes ov... more This paper describes an attempt to de®ne mesoscale daily precipitation and temperature regimes over Sardinia and their relation to different synoptic patterns. In order to address this task an extensive Cluster Analysis was performed on the whole data set using a number of methods, each including several distance measures. Thirty years of daily data, for the period ranging from 1951 to 1980 for the 114 stations with precipitation and 20 with temperature, were used in the study. In order to retrieve homogeneous clusters, non-hierarchical methods were found to be more effective and the use of a correlation-like distance was more effective for precipitation. To discriminate between the different clusters, the corresponding mean mass ®elds for the 500 hPa height and sea level pressure were used and an analysis of synoptic situations linked to mesoscale regimes was performed. The results show that at least two mean surface patterns exist corresponding to clearly different synoptic situations. Nevertheless, physical considerations led us to consider three distinct clusters, two of which correspond to speci®c synoptic circulations with slight, but meteorologically signi®cant, differences.
Numerical simulations of idealized stratified flows over obstacles at different spatial scales de... more Numerical simulations of idealized stratified flows over obstacles at different spatial scales demonstrate the very general applicability and the parallel efficiency of a new nonhydrostatic dynamical core for simulation of mesoscale flows over complex terrain.
Three diverse methods of initializing soil moisture and temperature in limited-area numerical wea... more Three diverse methods of initializing soil moisture and temperature in limited-area numerical weather prediction models are compared and assessed through the use of nonstandard surface observations to identify the approach that best combines ease of implementation, improvement in forecast skill, and realistic estimations of soil parameters. The first method initializes the limited-area model soil prognostic variables by a simple interpolation from a parent global model that is used to provide the lateral boundary conditions for the forecasts, thus ensuring that the limited-area model's soil field cannot evolve far from the host model. The second method uses the soil properties generated by a previous limited-area model forecast, allowing the soil moisture to evolve over time to a new equilibrium consistent with the regional model's hydrological cycle. The third method implements a new local soil moisture variational analysis system that uses screen-level temperature to adjust the soil water content, allowing the use of high-resolution station data that may be available to a regional meteorological service. The methods are tested in a suite of short-term weather forecasts performed with the Consortium for Small Scale Modeling (COSMO) model over the period September-November 2008, using the ECMWF Integrated Forecast System (IFS) model to provide the lateral boundary conditions. Extensive comparisons to observations show that substantial improvements in forecast skills are achievable with improved soil temperature initialization while a smaller additional benefit in the prediction of surface fluxes is possible with the soil moisture analysis. The analysis suggests that keeping the model prognostic variables close to equilibrium with the soil state, especially for temperature, is more relevant than correcting the soil moisture initial values. In particular, if a local soil analysis system is not available, it seems preferable to adopt an ''open loop'' strategy rather than the interpolation from the host global model analysis. This appears to be especially true for the COSMO model in its current operational configuration since the soil-vegetation-atmosphere transfer (SVAT) scheme of the ECMWF global host model and that of COSMO are radically diverse.
The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SM... more The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on five selected members of ECMWF EPS. For the in- vestigated case studies, two different limited-area models (one hydrostatic and one non-hydrostatic) are used to generate LEPS and the forecast sensitivity to the type of limited-area model is studied for ranges between 72 and 120 hours. The attention is focused on the probabilistic prediction of total precipitation, so as to assess the possi- bility to issue flood alerts on the basis of probability maps generated by the limited- area models. Different model configurations are tested and the impact of enhanced horizontal resolution on quantitative precipitation forecast is studied. In all configura- tions, LEPS turns out to perform better than EPS to predict small scales, local severe events, thanks to the higher horizontal resolution and to the m...
In this paper we describe the results of several numerical experiments performed with the limited... more In this paper we describe the results of several numerical experiments performed with the limited area model LAMBO, based on a 1989 version of the NCEP (National Center for Environmental Prediction) ETA model, operational at ARPA-SMR since 1993. The experiments have been designed to assess the impact of different horizontal resolutions and initial conditions on the quality and detail of the forecast, especially as regards the precipitation field in the case of severe flood events. For initial conditions we developed a mesoscale data assimilation scheme, based on the nudging technique. The scheme makes use of upper air and surface meteorological observations to modify ECMWF (European Centre for Medium Range Weather Forecast) operational analyses, used as first-guess fields, in order to better describe smaller scales features, mainly in the lower troposphere. Three flood cases in the Alpine and Mediterranean regions have been simulated with LAMBO, using a horizontal grid spacing of 15...
International Journal of Climatology - INT J CLIMATOL, 2000
The interannual and decadal variability of seasonal precipitation (October through April) over Sa... more The interannual and decadal variability of seasonal precipitation (October through April) over Sardinia (Italy) is analysed for the years 1940-1995. It is shown that the area-average seasonal rainfall total can vary greatly from one year to the next. The spatial correlation of Sardinia seasonal rainfall with that of neighbouring Mediterranean regions is generally high, though the correlation is less to the south of Sardinia, suggesting other teleconnection structures may operate there.Over a slightly shorter period (1946-1993), correlations between precipitation and large-scale variables (sea level pressures (SLP), 500 hPa geopotential heights (Z500) and sea surface temperatures (SST)) are calculated and analysed. Clear connections between the North Atlantic Oscillation (NAO) and Sardinian precipitation are found and studied. Contrasting Atlantic storm tracks were found for the wet and dry seasons. In the wet years, the track is weaker over the North Atlantic (consistent with the NA...
At the national level, in Italy, observational and forecast data are collected by various public ... more At the national level, in Italy, observational and forecast data are collected by various public bodies and are often kept in various small, heterogeneous and non‐interoperable repositories, released under different licenses, thus limiting the usability for external users. In this context, MISTRAL (the Meteo Italian SupercompuTing PoRtAL) was launched as the first Italian meteorological open data portal, with the aim of promoting the reuse of meteorological data sets available at national level coverage. The MISTRAL portal provides (and archives) meteorological data from various observation networks, both public and private, and forecast data that are generated and post‐processed within the Consortium for Small‐scale Modeling‐Limited Area Model Italia (COSMO‐LAMI) agreement using high performance computing (HPC) facilities. Also incorporated is the Italy Flash Flood use case, implemented with the collaboration of European Centre for Medium‐Range Weather Forecasts (ECMWF), which exploits cutting edge advances in HPC‐based post‐processing of ensemble precipitation forecasts, for different model resolutions, and applies those to deliver novel blended‐resolution forecasts specifically for Italy. Finally, in addition to providing architectures for the acquisition and display of observational data, MISTRAL also delivers an interactive system for visualizing forecast data of different resolutions as superimposed multi‐layer maps.
Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood... more Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region - The Mesoscale Alpine Programme (MAP, the first WWRP Research and Development Project (RDP)) is an international research initiative devoted to the study of atmospheric and hydrological processes over mountainous terrain. It aims towards expanding our knowledge of weather and climate over complex topography, and thereby to improve current forecasting capabilities. A large-scale field phase in the Alpine region took place from 7 September to 15 November 1999. D-PHASE (Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) is a WWRP Forecast Demonstration Project (FDP) and aims at demonstrating some of the many achievements of MAP, in particular the ability of forecasting heavy precipitation and related flooding events in the Alpine region. The MAP FDP will address the entire forecasting chain ranging from ...
Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood... more Project: D-PHASE, Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region - The Mesoscale Alpine Programme (MAP, the first WWRP Research and Development Project (RDP)) is an international research initiative devoted to the study of atmospheric and hydrological processes over mountainous terrain. It aims towards expanding our knowledge of weather and climate over complex topography, and thereby to improve current forecasting capabilities. A large-scale field phase in the Alpine region took place from 7 September to 15 November 1999. D-PHASE (Demonstration of Probabilistic Hydrological and Atmospheric Simulation of flood Events in the Alpine region) is a WWRP Forecast Demonstration Project (FDP) and aims at demonstrating some of the many achievements of MAP, in particular the ability of forecasting heavy precipitation and related flooding events in the Alpine region. The MAP FDP will address the entire forecasting chain ranging from ...
Numerical weather prediction models (NWP) are today the best suitable tools for temperature forec... more Numerical weather prediction models (NWP) are today the best suitable tools for temperature forecast. Nevertheless, raw model output is strongly affected by systematic errors, mostly due to the rough representation of orography; such errors can be partially corrected by Model Output Statistics techniques (MOS). In this study, aiming to operate frost alerting in Trentino, both linear and nonlinear MOS algorithms are compared in predicting minimum temperature in the middle Adige Valley area. Two NWP models have been used, one Global Circulation Model (ECMWF T511 - L60) and one Local Area Model (LAMI). The following post-processing techniques have been employed: mean bias correction, multilinear regression, neural networks, random forest (RF). The latter was selected as the best performing method, and applied to the nine points (for ECMWF) and to the 21 points (LAMI) surrounding the target area. Results show that multivariate models display the best skill, but with little difference am...
W swoim artykule proponuję spojrzenie na literaturę polską w Izraelu 1 jako na literaturę "wielki... more W swoim artykule proponuję spojrzenie na literaturę polską w Izraelu 1 jako na literaturę "wielkiego przemieszczenia"-to znaczy literaturę związaną z migracjami i tworzoną przez migrantów. Niezależnie bowiem od wszelkich innych możliwych interpretacji 2 , piśmiennictwo powstające w Izraelu w językach diasporyi związane z kolejnymi falami aliji-potraktowane być może w najszerszym kulturowym ujęciu jako twórczość, która stanowi odpowiedź na doświadczenie przemieszczenia terytorialnego i związanego z nim funkcjonowania pomiędzy różnymi kulturami 3 .
The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SM... more The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on five selected members of ECMWF EPS. For the in- vestigated case studies, two different limited-area models (one hydrostatic and one non-hydrostatic) are used to generate LEPS and the forecast sensitivity to the type of limited-area model is studied for ranges between 72 and 120 hours. The attention is focused on the probabilistic prediction of total precipitation, so as to assess the possi- bility to issue flood alerts on the basis of probability maps generated by the limited- area models. Different model configurations are tested and the impact of enhanced horizontal resolution on quantitative precipitation forecast is studied. In all configura- tions, LEPS turns out to perform better than EPS to predict small scales, local severe events, thanks to the higher horizontal resolution and to the m...
Tellus A: Dynamic Meteorology and Oceanography, 2011
In this work, the main characteristics of COSMO-LEPS, the Limited-area Ensemble Prediction System... more In this work, the main characteristics of COSMO-LEPS, the Limited-area Ensemble Prediction System developed in the framework of the COnsortium for Small-scale MOdelling, are presented. The present status of the system is shown with the description of the methodology and of the main upgrades which took place during its years of activity. The performance of COSMO-LEPS for the probabilistic prediction of precipitation is assessed in terms of both time-series and seasonal scores over a 7-yr period. A fixed number of stations are selected and observations are compared to short and early medium-range forecasts. Different verification indices are used to assess the skill of COSMO-LEPS and to identify the impact of system modifications on forecast skill. The different system upgrades are found to impact positively on COSMO-LEPS performance, with a gain of 2 d of predictability in the last 4 yr of operational forecasts. This holds when the skill of the system is assessed both for single events (e.g. precipitation surpassing a fixed threshold) and for multi-event situations. Scores for fixed forecast ranges but varying thresholds confirm increasingly better performance of the system. For a few seasons, the performance of COSMO-LEPS is also assessed in terms of probabilistic prediction of some upper-air variables. Then, the skill of COSMO-LEPS is compared to that of the global-ensemble system providing the boundaries, to identify the extent to which skill improvements may relate to those of the driving ensemble. Finally, the main streams of development for COSMO-LEPS system are discussed with future possible upgrades and methodology modifications.
As commonly known, the initialisation of soil properties (temperature, moisture content and land ... more As commonly known, the initialisation of soil properties (temperature, moisture content and land coverage) can strongly affect the quantitative precipitation forecast of a numerical model, particularly in those cases in which the moisture supply is provided by local evaporation. Nevertheless, widely routine observations of soil surface properties (i.e. soil moisture content) are not available in real time. This is the reason for which we planned to use the output of a Soil-Vegetation-Atmosphere Transfer (SVAT) scheme, named LSPM (Land Surface Process Model, Cassardo et al., 1995 and 1998), to simulate soil surface temperature and moisture fields which can be also used as suitable initial conditions of a LAM integration (Balsamo et. al, 1999). The frame of the work is CLIPS (CLImatology of Parameters at the Surface) project The use of LSPM can provide realistic estimates of surface energy, thermal and hydrological budgets (Cassardo et al., 1977, and Ruti et al., 1997). Using this procedure for a long time period (several months), another goal of CLIPS experiment is to create a climatological archive of surface data on the MAP area, including also mountain stations. Precipitation Evaporation Runoff Drainage Figure 3-Components of hydrological budget cumulated on September 1995, in mm.
Presso ARPA-SIM viene utilizzato da alcuni anni il modello di previsione meterologica ad area lim... more Presso ARPA-SIM viene utilizzato da alcuni anni il modello di previsione meterologica ad area limitata Lokal Modell (LM), sviluppato inizialmente dal servizio meteorologico tedesco DWD e attualmente gestito dal Consorzio COSMO a cui partecipano, tra gli altri, vari servizi meteorologici nazionali europei. Si tratta di un modello meteorologico di ultima generazione, non idrostatico e adatto per sistemi di calcolo parallelo a memoria distribuita mediante la libreria MPI. La suite previsionale operativa di LM presso ARPA-SIM copre tutto il territorio nazionale con una griglia dal passo di 7 km circa ed effettua 2 previsioni al giorno fino a 72 ore di scadenza. Recentemente la suite operativa e stata portata su un sistema Linux/GNU installato presso ARPA-SIM, utilizzato come backup della suite principale attiva su IBM SP4 al Cineca. Il sistema, costruito con hardware comunemente disponibile e software quasi tutto open-source, comprende 44 processori Intel Xeon, interconnessi da una rete...
Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2000
ABSTRACT The development of efficient remote sensing tools, satellite and ground-based, calls for... more ABSTRACT The development of efficient remote sensing tools, satellite and ground-based, calls for an integrated use of the newly available data and NWP techniques to produce very-short-range operational forecasts. The Local Analysis and Prediction System (LAPS) has been developed by NOAA-FSL as an integrated system to ingest and analyse meteorological data from different observational sources, i.e. mesonet and regular surface data, radar and profiler data, and satellite imagery. The resulting 3-D data-set contains all relevant meteorological parameters, that is temperature, pressure, humidity, wind, clouds, and other derived variables. Radar data play a key role in accurately describing the mesoscale wind pattern, when no others observational sources are available, particularly at low level where the correlation coefficient between radar analysis vs raob analysis grew at 0.99-0.95. The resulting fields are used in a continuous assimilation cycle with a limited area model for improving the forecast skill over a meso-β domain. The overall system is presented highlighting the impact of Doppler radar data in the reconstruction of missing features and comparing the different scenarios that can be foreseen.
This paper describes an attempt to de®ne mesoscale daily precipitation and temperature regimes ov... more This paper describes an attempt to de®ne mesoscale daily precipitation and temperature regimes over Sardinia and their relation to different synoptic patterns. In order to address this task an extensive Cluster Analysis was performed on the whole data set using a number of methods, each including several distance measures. Thirty years of daily data, for the period ranging from 1951 to 1980 for the 114 stations with precipitation and 20 with temperature, were used in the study. In order to retrieve homogeneous clusters, non-hierarchical methods were found to be more effective and the use of a correlation-like distance was more effective for precipitation. To discriminate between the different clusters, the corresponding mean mass ®elds for the 500 hPa height and sea level pressure were used and an analysis of synoptic situations linked to mesoscale regimes was performed. The results show that at least two mean surface patterns exist corresponding to clearly different synoptic situations. Nevertheless, physical considerations led us to consider three distinct clusters, two of which correspond to speci®c synoptic circulations with slight, but meteorologically signi®cant, differences.
Numerical simulations of idealized stratified flows over obstacles at different spatial scales de... more Numerical simulations of idealized stratified flows over obstacles at different spatial scales demonstrate the very general applicability and the parallel efficiency of a new nonhydrostatic dynamical core for simulation of mesoscale flows over complex terrain.
Three diverse methods of initializing soil moisture and temperature in limited-area numerical wea... more Three diverse methods of initializing soil moisture and temperature in limited-area numerical weather prediction models are compared and assessed through the use of nonstandard surface observations to identify the approach that best combines ease of implementation, improvement in forecast skill, and realistic estimations of soil parameters. The first method initializes the limited-area model soil prognostic variables by a simple interpolation from a parent global model that is used to provide the lateral boundary conditions for the forecasts, thus ensuring that the limited-area model's soil field cannot evolve far from the host model. The second method uses the soil properties generated by a previous limited-area model forecast, allowing the soil moisture to evolve over time to a new equilibrium consistent with the regional model's hydrological cycle. The third method implements a new local soil moisture variational analysis system that uses screen-level temperature to adjust the soil water content, allowing the use of high-resolution station data that may be available to a regional meteorological service. The methods are tested in a suite of short-term weather forecasts performed with the Consortium for Small Scale Modeling (COSMO) model over the period September-November 2008, using the ECMWF Integrated Forecast System (IFS) model to provide the lateral boundary conditions. Extensive comparisons to observations show that substantial improvements in forecast skills are achievable with improved soil temperature initialization while a smaller additional benefit in the prediction of surface fluxes is possible with the soil moisture analysis. The analysis suggests that keeping the model prognostic variables close to equilibrium with the soil state, especially for temperature, is more relevant than correcting the soil moisture initial values. In particular, if a local soil analysis system is not available, it seems preferable to adopt an ''open loop'' strategy rather than the interpolation from the host global model analysis. This appears to be especially true for the COSMO model in its current operational configuration since the soil-vegetation-atmosphere transfer (SVAT) scheme of the ECMWF global host model and that of COSMO are radically diverse.
The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SM... more The predictability of some MAP IOPs is investigated by considering the performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on five selected members of ECMWF EPS. For the in- vestigated case studies, two different limited-area models (one hydrostatic and one non-hydrostatic) are used to generate LEPS and the forecast sensitivity to the type of limited-area model is studied for ranges between 72 and 120 hours. The attention is focused on the probabilistic prediction of total precipitation, so as to assess the possi- bility to issue flood alerts on the basis of probability maps generated by the limited- area models. Different model configurations are tested and the impact of enhanced horizontal resolution on quantitative precipitation forecast is studied. In all configura- tions, LEPS turns out to perform better than EPS to predict small scales, local severe events, thanks to the higher horizontal resolution and to the m...
In this paper we describe the results of several numerical experiments performed with the limited... more In this paper we describe the results of several numerical experiments performed with the limited area model LAMBO, based on a 1989 version of the NCEP (National Center for Environmental Prediction) ETA model, operational at ARPA-SMR since 1993. The experiments have been designed to assess the impact of different horizontal resolutions and initial conditions on the quality and detail of the forecast, especially as regards the precipitation field in the case of severe flood events. For initial conditions we developed a mesoscale data assimilation scheme, based on the nudging technique. The scheme makes use of upper air and surface meteorological observations to modify ECMWF (European Centre for Medium Range Weather Forecast) operational analyses, used as first-guess fields, in order to better describe smaller scales features, mainly in the lower troposphere. Three flood cases in the Alpine and Mediterranean regions have been simulated with LAMBO, using a horizontal grid spacing of 15...
International Journal of Climatology - INT J CLIMATOL, 2000
The interannual and decadal variability of seasonal precipitation (October through April) over Sa... more The interannual and decadal variability of seasonal precipitation (October through April) over Sardinia (Italy) is analysed for the years 1940-1995. It is shown that the area-average seasonal rainfall total can vary greatly from one year to the next. The spatial correlation of Sardinia seasonal rainfall with that of neighbouring Mediterranean regions is generally high, though the correlation is less to the south of Sardinia, suggesting other teleconnection structures may operate there.Over a slightly shorter period (1946-1993), correlations between precipitation and large-scale variables (sea level pressures (SLP), 500 hPa geopotential heights (Z500) and sea surface temperatures (SST)) are calculated and analysed. Clear connections between the North Atlantic Oscillation (NAO) and Sardinian precipitation are found and studied. Contrasting Atlantic storm tracks were found for the wet and dry seasons. In the wet years, the track is weaker over the North Atlantic (consistent with the NA...
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Papers by Davide Cesari