DATE2016-06-02 11:14:52
AUTHORSRusso A. (1), Ramos A.M. (1), Gouveia C. M. (1), Ramos P. (1), Trigo R.M. (1)
  1. Idl Lisbon (Portugal)
ABSTRACTThe Mediterranean is often affected by drought events with strong influences in ecosystems and the related social and economic impacts [1,2]. In the last decades the severity of droughts in Iberia has increased due to the higher atmospheric evaporative demand [3]. Moreover, Europe has also experienced multiple and unprecedented mega heat waves, namely Western Europe in 2003 [4] and Eastern Europe in 2010 [5]. In Southern Europe droughts and heat waves are two of the most frequent EW events [6], having negative impacts on several economic and social activities. As global warming increases, the likelihood of hot extremes also rises [7]. In this context it is becoming increasingly relevant to improve the predictability of such events. A number of diagnostic and modelling experiments have confirmed that hot extremes in Europe and USA are often preceded by surface moisture deficits in some regions. Thus, in this study, we propose to assess the strength of such a relationship throughout the entire Mediterranean area. In order to achieve this purpose, the number of hot days in the regions’ hottest month will be associated with a drought indicator. The evolution and characterization of drought in the Mediterranean was analyzed using the Standardized Precipitation Evaporation Index (SPEI) as obtained from CRU TS3.21 database for the period 1901-2012. We have used SPEI for different time scales between 3 and 18 months, using a spatial resolution of 0.5º. The number of hot days per month (NHD) was determined based on the ECAD-EOBS daily dataset using a spatial resolution of 0.5º. The NHD was calculated as the number of days with a maximum temperature exceeding the 90th percentile. In the main analyses, the most frequent hottest months in the Mediterranean are July and August and results were developed on a regional basis (e.g. Iberia, France, Balkans) evaluating the identification of the regions of strongest correlation between surface moisture deficits and temperature extremes. [1] Gouveia et al, 2012. NHESS, 12, 3123-3137. [2] Trigo et al., 2013. BAMS, 94 (9), S41-S45. [3] Vicente-Serrano S.M. et al., 2014.Env. Res. Letters, 9, 044001, 2014. [4] Garcia-Herrera R. et al., 2007. J. Hidrom., 8, 483-498. [5] Bastos A. et al., 2014. Biogeosciences, 11, 3421-3435, doi:10.5194/bg-11-3421-2014, 2014. [6] Hov Ø et al., 2013. ISBN (electronic) 978-82-7144-101-2. [7] Fischer and Knutti, 2015. Nature Climate Change, 5, 560–564.