Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 20, 3777-3788, 2016
http://www.hydrol-earth-syst-sci.net/20/3777/2016/
doi:10.5194/hess-20-3777-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
13 Sep 2016
Spatio-temporal trends in the hydroclimate of Turkey for the last decades based on two reanalysis datasets
Mustafa Gokmen 1The Ministry of Environment and Urbanization, Ankara, Turkey
2The Research Association of Rural Environment and Forestry, Ankara, Turkey
Abstract. We present a regional assessment of the spatiotemporal trends in several hydro-climate variables from 1979 to 2010 in Turkey, one of the countries of the eastern Mediterranean vulnerable to climate change, using the two reanalysis products of the ECMWF: ERA-Interim and ERA-Interim/Land. The trend analysis revealed that an average warming of 1.26 °C [0.8–1.8] occurred in Turkey from 1979 to 2010, with high confidence intervals (95–99 %, mostly). Geographically, the largest warming (up to 1.8 °C) occurred in the western coastal areas next to the Aegean Sea and in the southeastern regions. The air temperature trends were generally confirmed by the in situ data from about 100 weather stations around the country, though in situ data indicated slightly higher trends ranging from 1 to 2.5°. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures: the ERA-Interim dataset indicated that there have been significant decreasing trends of precipitation, snow water equivalent (SWE) and runoff in some parts of inner/southeastern Anatolia (a total decrease of up to 250 mm in the upstream of the Euphrates, Kizilirmak and Seyhan basins), while ERA-Interim/Land showed no or minor trends in the same areas. Based on the extensive comparisons with precipitation and SWE gauge data, we can suggest that the hydrological trends shown by the ERA-Interim/Land dataset, which is said to be a model improvement, are relatively closer to the observations. From the hydrological trends revealed by the ERA-Interim/Land dataset, we can conclude that, despite the strong warming trends over Turkey from 1979 to 2010, there have been no widespread and strong hydrological trends for the same period throughout the country. In this regard, we can suggest that the impacts of global warming on the water cycle are not straightforward, especially at the regional scale, and future climate simulations indicating considerable reductions in precipitation along with the significant increases in temperatures throughout the Mediterranean and the Middle East by the end of the twenty-first century need to be dealt with cautiously.

Citation: Gokmen, M.: Spatio-temporal trends in the hydroclimate of Turkey for the last decades based on two reanalysis datasets, Hydrol. Earth Syst. Sci., 20, 3777-3788, doi:10.5194/hess-20-3777-2016, 2016.
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Short summary
Based on ECMWF's two reanalysis datasets, our assessment of the spatiotemporal trends revealed an average warming of 1.26 °C [0.8 to 1.8] in Turkey from 1979 to 2010. With respect to the regional trends in hydrological variables, ERA-Interim and ERA-Interim/Land revealed quite different pictures. Based on ERA-Interim/Land, which was closer to the observations, there have been no widespread and strong hydrological trends for the same period throughout the country despite the strong warming.
Based on ECMWF's two reanalysis datasets, our assessment of the spatiotemporal trends revealed...
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