Summer air temperature anomalies in Europe during the century 1811-1910

Solar cycle, volcanic eruptions, sea surface temperature anomalies (ENSO) and increase of the concentration of the greenhouse gases are the main forcing factors in the evolution of the Earth climate. Therefore, a sizeable amount of research is devoted to assess the impact of these factors on the climate parameters, as the mean air temperature. In the present work a study concerning the behaviour of the summer temperatures over Europe during the century 1811-1910 is carried out. The possible influence of the volcanic eruptions and ENSO has been also analysed. The results show the presence of a volcanic signal in the summer temperature during the year following an eruption, even if the anomalous coldest summers do not seem to be driven by the volcanic activity. The connection between thermal anomalies and ENSO events is more uncertain because of the paucity of data. Finally, the anomalous summers—both very cold and very warm—can be explained in terms of the atmospheric circulation, since cold events seem to be associated to persistent blocking systems and warm events are associated to persistent high-pressure patterns

Rainfall over the Central-Western Mediterranean basin in the period 1951-1995. Part I: precipitation trends

Climatic changes due to the anthropic enhancement of the greenhouse effect could modify the hydrological cycle, resulting in a reduction of the precipitation over the Mediterranean basin. In particular, a negative trend over the Italian peninsula could occur with prolonged periods of dryness as that recorded in the biennium 1988-1990. In order to verify if a climatic variability is already detectable, the pluviometric regime over the Central-Western Mediterranean is here analysed for the period 1951-1995. The analysis indicates that a reduction of about 20% in the total precipitation has occurred, which is statistically significant and can have serious impact on the availability of the water supplies

The application of LEPS technique for Quantitative Precipitation Forecast (QPF) in Southern Italy

International audienceThis paper reports preliminary results of a Limited area model Ensemble Prediction System (LEPS), based on RAMS, for eight case studies of moderate-intense precipitation over Calabria, the southernmost tip of the Italian peninsula. LEPS aims to transfer the benefits of a probabilistic forecast from global to regional scales in countries where local orographic forcing is a key factor to force convection. To accomplish this task and to limit computational time, in order to implement LEPS operational, we perform a cluster analysis of ECMWF-EPS runs. Starting from the 51 members that forms the ECMWF-EPS we generate five clusters. For each cluster a representative member is selected and used to provide initial and dynamic boundary conditions to RAMS, whose integrations generate LEPS. RAMS runs have 12 km horizontal resolution. Hereafter this ensemble will be referred also as LEPS_12L30. To analyze the impact of enhanced horizontal resolution on quantitative precipitation forecast, LEPS_12L30 forecasts are compared to a lower resolution ensemble, based on RAMS that has 50 km horizontal resolution and 51 members, nested in each ECMWF-EPS member. Hereafter this ensemble will be also referred as LEPS_50L30. LEPS_12L30 and LEPS_50L30 results were compared subjectively for all case studies but, for brevity, results are reported for two "representative" cases only. Subjective analysis is based on ensemble-mean precipitation and probability maps. Moreover, a short summary of objective scores. Maps and scores are evaluated against reports of Calabria regional raingauges network. Results show better LEPS_12L30 performance compared to LEPS_50L30. This is obtained for all case studies selected and strongly suggests the importance of the enhanced horizontal resolution, compared to ensemble population, for Calabria, at least for set-ups and case studies selected in this work

The meteorological model RAMS at Crati Scrl

International audienceAt Crati Scrl an operational version of RAMS 4.3 (Regional Atmospheric Modeling System) was implemented in January 2001. This paper aims to give a first assessment of model performances for quantitative precipitation forecast (QPF). In essence, the effects of enhanced horizontal grid resolution over Calabria, using a 6km spacing domain nested in a 30km resolution parent grid, is studied. To cope with this problem two integrations sets are discussed using two model resolutions. Integrations are performed daily for six months. ECMWF 12:00UTC forecast cycle is used for initial and dynamic boundary conditions. Performances are evaluated by scores computed from model outputs and raingauge measurements coming from Calabrian regional network

On the performance of a limited area model for quantitative precipitation forecast over Calabria

At Crati Scrl an operational version of RAMS 4.3 (Regional Atmospheric Modeling System), with a son grid over Calabria, was implemented in January 2001. This paper aims to give a first assessment of model performances for quantitative precipitation forecast (QPF). In particular two issues of weather forecast are discussed. First problem refers to effects introduced by enhanced resolution over Calabria, using a 6 km resolution grid nested in a 30 km parent grid. Second issue discusses forecast deterioration with increasing forecast time. To cope with these problems, two sets of integrations are discussed using two different model configurations. Differences between configurations are only due to model resolutions. Integrations are performed daily for six months. Each integration starts at 12 UTC and lasts for 60 h, with 12 h spin-up time. ECMWF 12 UTC analysis and following forecast are used as initial and dynamic boundary conditions. Models performances are evaluated computing scores by comparing model outputs with raingauges data coming from Calabria regional network. Results show better performances of finergrid resolution compared to the coarser one and confirms the usefulness of enhanced resolution over complex terrain. In addition, performances decrease with increasing forecast time with first integration day performing better than second forecast day but differences are not statistically significant at 5% level

Thermally forced mesoscale atmospheric flow over complex terrain in Southern Italy

In this paper we discuss some results concerning the analysis of the local atmospheric flow over the southern part of Italy, the Calabria peninsula, using a mesoscale numerical model. Our study is focused on two different but related topics: a detailed analysis of the meteorology and climate of the region based on a data collection, reported in Colacino et al., Elementi di Climatologia della Calabria, edited by A. GUERRINI, Collana P. S., Clima, Ambiente e Territorio nel Mezzogiorno (CNR, Roma) 1997, pp. 218, and an analysis of the results based on the simulated flow produced using a mesoscale numerical model. The Colorado State University mesoscale numerical model has been applied to study several different climatic situations of particular interest for the region, as discussed in this paper. In particular, the effects on the circulation over the region, due to the variation of different physical parameters as large-scale flow intensity, vertical potential temperature gradients, soil moisture, have been studied, and the seasonal variability of the Thermally Forced Mesoscale Circulations (TFMCs) is presented. The results show that thermally forced mesoscale circulation in the region is rather complex, and more pronounced than in regions located at the same latitude. The cells are strongly supported by the presence of the two breeze systems (sea-land and mountain-valley), and their location, shape and intensity are affected by the intensity of the large-scale flow, while atmospheric stability and soil moisture have a weaker influence on the TFMC structure. This study of the dynamics and thermodynamics of the atmosphere in this region, and particularly the analysis of the wind field, is preliminary for other related topics of research as agrometeorology, wind energy exploitation, environmental impact assessment, and for research related to tourism

Application of the LEPS technique for Quantitative Precipitation Forecasting (QPF) in Southern Italy: a preliminary study

International audienceThis paper reports preliminary results for a Limited area model Ensemble Prediction System (LEPS), based on RAMS (Regional Atmospheric Modelling System), for eight case studies of moderate-intense precipitation over Calabria, the southernmost tip of the Italian peninsula. LEPS aims to transfer the benefits of a probabilistic forecast from global to regional scales in countries where local orographic forcing is a key factor to force convection. To accomplish this task and to limit computational time in an operational implementation of LEPS, we perform a cluster analysis of ECMWF-EPS runs. Starting from the 51 members that form the ECMWF-EPS we generate five clusters. For each cluster a representative member is selected and used to provide initial and dynamic boundary conditions to RAMS, whose integrations generate LEPS. RAMS runs have 12-km horizontal resolution. To analyze the impact of enhanced horizontal resolution on quantitative precipitation forecasts, LEPS forecasts are compared to a full Brute Force (BF) ensemble. This ensemble is based on RAMS, has 36 km horizontal resolution and is generated by 51 members, nested in each ECMWF-EPS member. LEPS and BF results are compared subjectively and by objective scores. Subjective analysis is based on precipitation and probability maps of case studies whereas objective analysis is made by deterministic and probabilistic scores. Scores and maps are calculated by comparing ensemble precipitation forecasts against reports from the Calabria regional raingauge network. Results show that LEPS provided better rainfall predictions than BF for all case studies selected. This strongly suggests the importance of the enhanced horizontal resolution, compared to ensemble population, for Calabria for these cases. To further explore the impact of local physiographic features on QPF (Quantitative Precipitation Forecasting), LEPS results are also compared with a 6-km horizontal resolution deterministic forecast. Due to local and mesoscale forcing, the high resolution forecast (Hi-Res) has better performance compared to the ensemble mean for rainfall thresholds larger than 10mm but it tends to overestimate precipitation for lower amounts. This yields larger false alarms that have a detrimental effect on objective scores for lower thresholds. To exploit the advantages of a probabilistic forecast compared to a deterministic one, the relation between the ECMWF-EPS 700 hPa geopotential height spread and LEPS performance is analyzed. Results are promising even if additional studies are required

Extreme events in Italy from documentary sources: Venice as a case study

Venice risks to be submerged as a consequence of two problems: local land subsidence and sea level rise due to global warming. They both contribute to what is referred as Apparent Sea Level Rise (ASLR). Flooding Tides (locally: Acqua Alta) submerge Venice with an exponentially increasing frequency. The Acqua Alta is generated by a number of factors, the main of them being the Sirocco wind blowing over the Adriatic Sea, that ultimately displaces waters towards Venice. These extreme events have been investigated by using the documentary description of past floods, accurately reported over the last millennium, and tide gauge records for the recent period. A fundamental problem is to know the trend of the ASLR, possibly distinguishing between land subsidence and sea level components. Instrumental data go back to 1872 and a key point is to extend ourkno wledge back in time. Long-term ASLR has been investigated with the help of a biological indicator, i.e. the height of the green belt of the algae that live in the tidal range and whose upper front shows the average high tide level. Fortunately, in the first half of the 18th century, this indicator was accurately drawn by the famous painter Antonio Canaletto (1697-1768) and his pupils, mainly Bernardo Bellotto (1722-1780), in their photographic paintings made with an optical camera obscura. It has been possible to compare the tidal level, as it was in the 1700s and today. After careful spot investigation and minor corrections for some changes to the hydrological system occurred in the meantime, the bulk submersion of Venice estimated from the paintings is 61 ± 11 cm with average yearly trend 1.9 mm y−1

Mechanochemistry: New Tools to Navigate the Uncharted Territory of “Impossible” Reactions

Mechanochemical transformations have made chemists enter unknown territories, forcing a different chemistry perspective. While questioning or revisiting familiar concepts belonging to solution chemistry, mechanochemistry has broken new ground, especially in the panorama of organic synthesis. Not only does it foster new “thinking outside the box”, but it also has opened new reaction paths, allowing to overcome the weaknesses of traditional chemistry exactly where the use of well-established solution-based methodologies rules out progress. In this Review, the reader is introduced to an intriguing research subject not yet fully explored and waiting for improved understanding. Indeed, the study is mainly focused on organic transformations that, although impossible in solution, become possible under mechanochemical processing conditions, simultaneously entailing innovation and expanding the chemical space