Recent climate trends over Greece

Abstract

Temperature and humidity play a key role in climate change assessment. This study focuses on the analysis of surface and upper-air temperature and humidity trends for a domain centered over the Greek region in the Eastern Mediterranean. The main purpose of this work is to investigate whether possible changes in the climate of the greater Greek region exist over the recent years. ERA-Interim reanalysis, surface and radiosonde observational data of air temperature, specific and relative humidity are used for a 39-year period (1979–2017). Through the spatial distribution of their trends, at different atmospheric pressure levels and seasons, it is possible to detect statistically significant spatial and temporal changes in the troposphere and stratosphere above the examined domain. Statistically significant warming trends at the 99% level are found at the surface over land and at the 95% level over sea during spring and summer for Greece; less pronounced and more sparsely distributed trends are identified during autumn and winter. Additionally, positive trends prevail throughout the entire extent of the troposphere, more pronounced during summer, whereas the stratosphere is characterized by negative trends. Trends derived from the reanalysis and observational data exhibit high degree of correlation both at surface and at upper atmospheric levels. In accordance, specific humidity has generally increased in the lower troposphere. Relative humidity time series demonstrate trends, which vary seasonally and geographically, due to its relationship with specific humidity and temperature.