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Global change affects precipitation and small modifications in rainfall regimes could compromise water availability, especially in areas characterized by a strong seasonality and a climate ranging from dry sub‐humid to semi‐arid. Drought, in particular, is a creeping phenomenon defined as an important temporary decrease in water availability below the expected value in a certain period and a specific area. Among the different methodologies for analysing drought periods, one of the most used is the evaluation of dry spells. The aim of this study is to investigate spatial and temporal changes in dry spells in Tuscany during the period 1955–2017, by using daily precipitation data. Changes in the number of dry days, maximum duration and 75th percentile of the duration of the dry spells were investigated. Three precipitation thresholds were selected: 1, 5 and 10 mm. The analyses were carried out at annual, September–May, September–November and December–May level. Theil–Sen nonparametric method was used to estimate the slope; Mann–Kendall test and a modification of it, which applies a trend‐free pre‐whitening (TFPW) method to the series having a serial correlation, were applied to look for statistically significant trends. The drought indicators showed increasing trends (some significant) especially at December–May and to a lesser extent at the annual and September–May level; the most pronounced increases were found in the southernmost areas of Tuscany. During September–November period, on the other hand, a prevalence of decreasing trends (rarely significant), with less pronounced decreases in the south of the region, were observed. Mediterranean area is considered a climate change "hot‐spot" from the viewpoint of vulnerability. An increase in long‐lasting dry spells, especially in southern Tuscany, can exacerbate the problems linked to water management and demand. [ABSTRACT FROM AUTHOR]

Abstract

ABSTRACT: During the last few decades, weather circulation type classifications (CTCs) have been widely used to gain insight into processes at the synoptic scale, but also for studying the relationship between atmospheric circulation and surface climate variability. This study aims to evaluate the best performing CTCs based on COST733 software for the stratification of daily ground‐level precipitation and surface air temperature across Italy by means of four statistical metrics. Six classification methods belonging to the four COST733 groups (threshold‐based, PCA‐based, leader algorithms and optimization algorithms) were investigated on 32 and 26 data time series derived from Italian weather stations for daily mean temperature and daily mean precipitation, respectively. CTCs were computed using gridded mean sea level pressure and geopotential height at 500 hPa derived from the NCEP Reanalysis 2 dataset between 1979 and 2015 and tested on three different numbers of classes (8/9, 11/12 and 18 circulation types). Evaluation metrics showed an evident seasonal variability and high‐spatial heterogeneity reflecting the geographical complexity of the Italian territory. The study points out that the best classification, both for temperature and precipitation, is strongly dependent on the classification variable (mean sea level pressure and geopotential height at 500 hPa) showing relevant differences between surface temperature and precipitation. A low number of circulation types (8/9) resulted as the most appropriate grouping for the Italian domain and the Principal Component Transversal and Simulated Annealing were the best performing classification procedures for ground‐level precipitation and temperature stratification, respectively. [ABSTRACT FROM AUTHOR]

Aedes albopictus (Skuse) is an invasive mosquito species that has spread to many countries in temperate regions bordering the Mediterranean basin, where it is becoming a major public health concern. A good knowledge of the thermal features of the most productive breeding sites for Ae. albopictus is crucial for a better estimation of the mosquitoes' life cycle and developmental rates. In this article, we address the problem of predicting air temperature in three microhabitats common in urban and suburban areas and the air and water temperature inside an ordinary catch basin, which is considered the most productive breeding site for Ae. albopictus in Italy. Temperature differences were statistically proven between the three microhabitats and between the catch basin external and internal temperature. The impacts on the developmental rates for each life stage of Ae. albopictus were tested through a parametric function of the temperature, and the aquatic stages resulted as being the most affected using the specific temperature inside a typical catch basin instead of a generic air temperature. The impact of snow cover on the catch basin internal temperature, and consequently on the mortality of diapausing eggs, was also evaluated. These data can be useful to improve epidemiological models for a better prediction of Ae. albopictus seasonal and population dynamics in central-northern Italian urban areas. [ABSTRACT FROM AUTHOR]