Transient high-resolution regional climate simulation for Greece over the period 1960-2100: Evaluation and future projections

Abstract

A transient regional climate model simulation with a spatial grid resolution of 10 km (RCM10), nested to a regional simulation with 25 km resolution (RCM25), was carried out over Greece with RegCM3 for the period 1960-2100 under the IPCC A1B scenario. RCM10 precipitation and temperature fields depict the finer regional characteristics over the complex Greek terrain compared to RCM25, but a station-based evaluation for the period 1975-2000 does not reveal a considerable improvement in RCM10 compared to RCM25. Future projections for the early-future period 2021-2050 indicate small changes, with annual temperature increasing mostly over land by less than 1.8°C and precipitation changing by ±15%, being mostly negative in the southern part of the domain. At the end of the century (2071-2100), the projected changes become larger, with mean annual temperature increasing by about 3.4 to 4.2°C over land and by 2.6 to 3.4°C over the sea and precipitation decreasing by 10 to 40%, with a positive gradient from the north to the south. Summer presents the largest future increase in mean near-surface temperature over the Greek mainland, while winter and spring show the largest decreases in precipitation rate. The number of hot days, warm nights, night frosts and continuous dry spell days and length of the growing season are projected to increase slightly in the near-future period, but markedly and consistently in the late 21st century future period in accordance with the generally warmer and drier climate projected from the RCM10 simulation.