Precipitation variability and change in the Calabria region (Italy) from a high resolution daily dataset

Abstract

The present study aims at improving data availability and quality for the last 80-90 years for daily precipitation in the Calabria region (southern Italy). First, the original database was homogenised and the gaps filled in for 129 daily rain gauges for the 1916-2006 period. Then, precipitation variability and change were evaluated at an adequate spatial resolution. Monthly and annual total precipitation (P), number of wet days (WDs), and precipitation intensity (PI) were calculated for each series. With regard to the monthly total precipitation a general negative trend, albeit not everywhere significant, was detected, in particular for the autumn-winter period, while in summer the tendency was toward an increase in total precipitation. The monthly behaviour of WDs was not very different from that observed for P: a diffuse negative trend was detected in most months, particularly evident and significant in January, with the exception of April and the summer months, for which the tendency was toward an increase. Regarding the PI, a general negative and often significant trend was found for the entire region and for almost all the months, except summer. Attention was also focused on tendencies in the different PI categories, revealing negative trends in high-intensity categories, especially coming from the winter season.Finally, running trend analysis revealed that the previously discussed tendencies were not persistent throughout the series length, but depended on the period examined. This important aspect should be taken into account when different results based on different time windows are compared.

Phytoclimatic map of Calabria (Southern Italy)

“…Particular attention was paid to problems arising from inhomogeneities of these data series. Specifically, the homogenization approach applied in this work to temperature series was similar to that discussed in Brunetti et al (2012), who performed a multiple application of the Craddock test (Craddock, 1979) for the precipitation field to remove inhomogeneities, but adapted to temperature. The homogenization procedure was applied to both maximum and minimum temperature series.…”

Changes in daily precipitation extremes in the Mediterranean from 1951 to 2010: the Basilicata region, southern Italy

“…Outliers were identified by the comparison of daily values among neighbouring observatories and then manually assessed as performed by other authors such as Brunetti et al (2001) in Italy, Griffiths et al (2003) and Manton et al (2001) in the South Pacific, Aguilar et al (2005) The second step tested the homogeneity of the reconstructed series. As argued by Brunetti et al (2004bBrunetti et al ( , 2012, series of daily precipitation could be affected by two kinds of inhomogeneities: (1) in the precipitation amount and (2) in the number of rainy days (WDs), with the latter being able to generate inhomogeneity also in the precipitation amount series. Periods with missing data might be interpreted as periods with an underestimation of total precipitation and might be corrected roughly by increasing each single rainy day and originating some erroneous extreme events.…”

“…The test is based on the hypothesis of the constancy of precipitation ratios. After the identification of the inhomogeneities, and once it has been decided to correct one break, we choose the series to estimate the adjustments among the neighbouring series that result homogeneous in a sufficiently long sub-period centred on the break year, and that correlate well with the candidate one as proposed by Brunetti et al (2012).…”

Effects of Climate Change on the Irrigation Scheduling Parameters in Calabria (South Italy) during 1925-2013

“…Measured meteorological variables (minimum and maximum air temperature and precipitation) and the derived agro meteorological index ET 0 were analyzed in order to evaluate if any time trend does exist and how it affects the irrigation scheduling parameters (irrigation amount and frequency) for citrus and tomato groves. The area studied is a region characterized by highly complex precipitation and temperatures patterns [7,8,11,16,[23][24][25]. The studies cited have analyzed spatial and temporal distribution of precipitation, temperature and drought within this region; however the effects of climate change on irrigation scheduling parameters discussed in the present paper have not been the subject of previous investigation.…”