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Castel Guelfo di Bologna, Italy

Rotach M.W.,University of Innsbruck | Arpagaus M.,Federal Office for Meteorology and Climatology MeteoSwiss | Dorninger M.,University of Vienna | Hegg C.,Swiss Federal Institute of forest | And 2 more authors.
Natural Hazards and Earth System Science | Year: 2012

D-PHASE was a Forecast Demonstration Project of theWorldWeather Research Programme (WWRP) related to the Mesoscale Alpine Programme (MAP). Its goal was to demonstrate the reliability and quality of operational forecasting of orographically influenced (determined) precipitation in the Alps and its consequences on the distribution of run-off characteristics. A special focus was, of course, on heavy-precipitation events. The D-PHASE Operations Period (DOP) ran from June to November 2007, during which an end-to-end forecasting system was operated covering many individual catchments in the Alps, with their water authorities, civil protection organizations or other end users. The forecasting system's core piece was a Visualization Platform where precipitation and flood warnings from some 30 atmospheric and 7 hydrological models (both deterministic and probabilistic) and corresponding model fields were displayed in uniform and comparable formats. Also, meteograms, nowcasting information and end user communication was made available to all the forecasters, users and end users. D-PHASE information was assessed and used by some 50 different groups ranging from atmospheric forecasters to civil protection authorities or water management bodies. In the present contribution, D-PHASE is briefly presented along with its outstanding scientific results and, in particular, the lessons learnt with respect to uncertainty propagation. A focus is thereby on the transfer of ensemble prediction information into the hydrological community and its use with respect to other aspects of societal impact. Objective verification of forecast quality is contrasted to subjective quality assessments during the project (end user workshops, questionnaires) and some general conclusions concerning forecast demonstration projects are drawn. © 2012 Author(s).

Parlagreco L.,European Commission - Joint Research Center Ispra | Archetti R.,University of Bologna | Simeoni U.,University of Ferrara | Devoti S.,European Commission - Joint Research Center Ispra | And 2 more authors.
Journal of Coastal Research | Year: 2011

The response to a beach face nourishment of the Terracina barred beach (Tyrrhenian sea, Italy) is analyzed based on a bi-weekly data set of timex video-images collected during a 34-month period (January 2008 - October 2010). Proxies for shoreline and sandbar crest positions were extracted from video-images and compared with topo-bathymetric surveys. During the first 17 months part of the nourished sediments were moved seaward and a shore-parallel linear single-bar system was restored. Bar dynamic was mainly influenced by on/offshore movements in relation to storms occurrence. A cluster of southerly extreme storms with maximum wave height of 4m sharply reshaped the nearshore morphology and a new double-barred system developed. A new inner bar generated close to the shoreline and the pre-existing one migrated 50m offshore. After this morphological reset the outer bar remained inactive and preserved a linear morphology for the whole analyzed period. On the contrary, the new inner bar dynamic was characterized by limited cross-shore displacements and high alongshore morphologic variability. During the last 5 months of observations a single barred-system was restored since the outer bar crest lost its morphologic evidence. As a consequence the inner bar moved 20m offshore and straightened.

Grazzini F.,ARPA SIMC | Vitart F.,European Center for Medium Range Weather Forecasts
Quarterly Journal of the Royal Meteorological Society | Year: 2015

Historically, the objective identification of atmospheric wave-packets has been very elusive. However, interest in these important sources of atmospheric variability has recently increased, and some automated tracking methods have been proposed. The Rossby wave packet (RWP) tracking algorithms opened the way to different types of investigation, ranging from climatology and predictability to assessing the impact of climate change on wave packet characteristics. The present study investigates the relationship between predictability (intrinsic and practical, i.e. predictive skill in a numerical weather prediction model) and the properties of RWPs, such as temporal duration, spatial extension and their area of genesis. Results suggest a significant correlation between RWP length and medium-range skill over Europe and the Northern Hemisphere. Analysis of an ensemble system shows that the spread decreases when long-living RWPs are present in the forecast, supporting the hypothesis that part of the observed increase in skill could indeed be attributed to higher intrinsic predictability induced by RWPs. Higher than average medium-range forecast skill scores are often associated with the presence of long-lasting RWPs (duration of at least 8 days) in the initial conditions, with a source often located in the west Pacific. On the contrary, bad medium-range forecast skill scores tend to be associated with shorter RWPs coming from the central USA or western Atlantic. An analysis of the probabilistic skill scores confirms that predictive skill increases with the presence of long RWPs from the west Pacific, up to week 3. © 2015 Royal Meteorological Society.

Rossa A.,Centro Meteorologico Of Teolo | Haase G.,SMHI | Keil C.,German Aerospace Center | Keil C.,Ludwig Maximilians University of Munich | And 6 more authors.
Atmospheric Science Letters | Year: 2010

The COST-731 Action is focused on uncertainty propagation in hydrometeorological forecasting chains. The goals and activities of the ActionWorking Group 1 can be subdivided by (1) describing and studying the impact of imperfect observations, mostly from radar, (2) exploiting radar data assimilation as a promising avenue for improved short-range precipitation forecasts and (3) high-resolution ensemble forecasting. Activities of Working Group 1 are presented along with their possible significance for hydrological applications. Copyright © 2010 Royal Meteorological Society and Crown Copyright.

Pavan V.,ARPA SIMC | Doblas-Reyes F.J.,Catalan Institution for Research and Advanced Studies | Doblas-Reyes F.J.,Institute Catala Of Ciencies Del Clima Ic3
Climate Dynamics | Year: 2013

A statistical calibration scheme is applied to multi-model global seasonal ensemble reforecasts in order to predict the interannual variability of summer averaged surface maximum temperature over Italy. In some cases, this technique is shown to be able to improve the skill scores of the seasonal predictions during the last 35 years, with respect to the direct model output (DMO), using seasonal predictions initialised 1 month before the beginning of the season. It is shown that the presence of some skill in the DMO multi-model predictions is mostly due to the correct prediction of the observed secular trends in maximum temperature, and, partly, to the correct prediction of outliers, in particular, of the summer of 2003. At the same time, while the removal of trends produces a small reduction of skill in both the raw and calibrated predictions, the removal of outliers improves the performance of the calibration scheme. Once all trends and outliers are removed, the DMO predictions have no skill, while the calibrated predictions still present a detectable skill. The improvement introduced by the calibration are shown to be statistically significant by applying resampling techniques. It is shown that the reason of this partial success is linked to the fact that although the models present several shortcomings, some models can capture the existence of a weak large-scale signal, possibly linked with the presence of a summer teleconnection between the equatorial Pacific and Europe, with a spatial pattern substantially different from that associated with the temperature secular trend. The teleconnection is associated with a modulation of the quasi-stationary barotropic eddies in the Northern Hemisphere extra-tropics. © 2013 Springer-Verlag Berlin Heidelberg.

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