Unravelling Precipitation Trends in Greece since 1950s Using ERA5 Climate Reanalysis Data

Abstract

Precipitation is one of the most variable climatic parameters, as it is determined by many physical processes. The spatiotemporal characteristics of precipitation have been significantly affected by climate change during the past decades. Analysis of precipitation trends is challenging, especially in regions such as Greece, which is characterized by complex topography and includes several ungauged areas. With this study, we aim to shed new light on the climatic characteristics and inter-annual trends of precipitation over Greece. For this purpose, we used ERA5 monthly precipitation data from 1950 to 2020 to estimate annual Theil–Sen trends and Mann–Kendall significance over Greece and surrounding areas. Additionally, in order to analyze and model the nonlinear relationships of monthly precipitation time series, we used generalized additive models (GAMs). The results indicated significant declining inter-annual trends of areal precipitation over the study area. Declining trends were more pronounced in winter over western and eastern Greece, but trends in spring, summer and autumn were mostly not significant. GAMs showcased that the trends were generally characterized by nonlinearity and precipitation over the study area presented high inter-decadal variability. Combining the results, we concluded that precipitation did not linearly change during the past 7 decades, but it first increased from the 1950s to the late 1960s, consequently decreased until the early 1990s and, afterwards, presented an increase until 2020 with a smaller rate than the 1950–1960s.

In Search of Climate Crisis in Greece Using Hydrological Data: 404 Not Found

“…However, no such trend appears. These results do not contradict earlier studies by Stefanidis et al [40] and Varlas et al [41], both of which found climatic fluctuations rather than linear trends. The former identified precipitation decreases in 1981-2000 and increases since 2000.…”

Representation of a Post-Fire Flash-Flood Event Combining Meteorological Simulations, Remote Sensing, and Hydraulic Modeling

“…A meteorological station of the National Observatory of Athens (NOA) network at Agioi Theodoroi located approximately 8 km west-southwest of Kineta recorded 206.8 mm of 2-day rainfall on 24-25 November (daily data available from 'meteo'-a Greek weather portal [91]). This precipitation amount is extreme if one considers that the annual precipitation at this area is about 400-450 mm [92]. The WRF-ARW model simulation estimated 182.6 mm of 2-day rainfall at the same area, thus agreeing very well with the measurements.…”

Integration of Floating Solar Photovoltaic Systems with Hydropower Plants in Greece

“…The author estimated that the nominal power of the FPVs that can be installed in the existing 128 water reservoirs in the country, covering 10% to 30% of the water surface, varies between 4.77 GW to 14.31 GW while the annual solar electricity generation varies between 6,435.2 GWh to 19,305.6 GWh. Varlas et al [29] have reanalyzed the precipitation data in Greece since 1950s. The authors stated that the trends were characterized by nonlinearity and inter-decadal variability.…”