The Long-Term ERA5 Data Series for Trend Analysis of Rainfall in Italy

Abstract

Nowadays, the Mediterranean region is generally recognized as a climate change hot spot given its strong response to global warming, with relevant impacts on rainfall amount and distribution. Within this context, in this work the temporal variability of rainfall at annual, seasonal and monthly scale was analyzed in Italy using rainfall data extracted from the reanalysis dataset ERA5-Land during the period 1950–2020. In particular, rainfall trend magnitude and significance have been estimated by means of non-parametric tests applied to 3215 grid points falling within the Italian territory. The main results of this analysis evidenced only a few relevant trends at the annual scale, mostly involving northern Italy (positive trend) and the Sardinia region (negative trend). At seasonal scale, the results showed a marked negative trend in winter, characterizing almost all the Italian territory, while in the other seasons a positive trend was identified in the majority of grid points, especially in the Alps. Finally, at the monthly scale, September was identified as the month of the year with the highest percentage of grid points with positive trends mainly located in central, southern, and north-eastern Italy.

On the Use of Gridded Data Products for Trend Assessment and Aridity Classification in a Mediterranean Context: The Case of the Apulia Region

“…The analysis with station data then confirmed the weak changes in precipitation observed in neighboring areas of central and southern Italy over the last years, with a more evident reduction during the winter season [41][42][43][44][45][46][47]. This tendency was not captured by E-OBS data, which described nonsignificant positive trends in all seasons, while CRU data showed a better agreement with the pattern depicted by observational data, although with a markedly reduced variability in the results.…”

“…The analysis with station data then confirmed the weak changes in precipitation observed in neighboring areas of central and southern Italy over the last years, with a more evident reduction during the winter season [41][42][43][44][45][46][47]. This tendency was not captured by E-OBS data, which described nonsignificant positive trends in all seasons, while CRU data On annual scale, about 95% of the gauging network exhibited a nonsignificant trend for total precipitation, almost equally distributed between positive and negative signs, with a larger variability in the results observed at the stations located above 300 m a.s.l.…”

Spatio-Temporal Interpolation and Bias Correction Ordering Analysis for Hydrological Simulations: An Assessment on a Mountainous River Basin

“…Although ERA5-Land is a new released product of current climatic variables, its utilization as reference data is justified by the numerous studies indicating their accuracy and applicability. Chiaravalloti et al [70] used the ERA5-Land for the precipitation spatial distribution analysis over Italy, while Gleixner et al [71] show that the annual cycle of the precipitation over the East Africa is well represented by the ERA5, diminishing the discrepancies during the rainy season. Tarek et al [72] demonstrate the reduction of the ERA5 temperature and precipitation biases against the ERA-Interim product.…”

Climate Scenarios for Coastal Flood Vulnerability Assessments: A Case Study for the Ligurian Coastal Region

“…ERA5-derived data on climate variables relevant to the development of flood events has previously been used to study climate change impacts in the Mediterranean Sea and over the Italian territory [54]. When it comes to the description of sea-level changes, previous literature highlighted how ERA5's horizontal resolution might lead to poor results in particularly narrow regional seas [55].…”