Future predictions of precipitation and temperature in Iraq using the statistical downscaling model
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ORIGINAL PAPER
Future predictions of precipitation and temperature in Iraq using the statistical downscaling model Mustafa Al-Mukhtar 1
&
Mariam Qasim 1,2
Received: 9 October 2018 / Accepted: 21 December 2018 # Saudi Society for Geosciences 2019
Abstract Iraq is facing a critical water crisis that has ever experienced. This necessitates a wise management for present and future water resources. Future water availability is mainly influenced by the impacts of climate changes and to dams in Turkey, Syria, Iran, and northern Iraq. The meteorological parameters obtained from global circulation models (GCM) cannot be used to assess the impacts of future climate changes on the water resources availability at catchment scale. The dynamical or statistical downscaling is employed to transfer the coarse resolution of GCM into a finer. In this study, the future maximum/minimum temperature and precipitation for 12 stations of Iraq were projected for three future periods 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100) from the Canadian GCM model (CanESM2) under different scenarios (RCP2.5, RCP4.5, and RCP8.5) using statistical downscaling model (SDSM). The model was set up utilizing partial correlation and significance level of 0.05 between National Center for Environmental Prediction/Atmospheric Research (NCEP/NCAR) parameters as predictors and the local station data as predictand. Subsequently, the model was calibrated and validated against daily data by using 70% of the data for calibration and the remaining 30% for the validation. Thereafter, the calibrated model was applied to downscale future scenarios of CanESM2 predictors. The study proved a satisfactory performance of SDSM for simulation of maximum-minimum temperatures and precipitation for future periods. All considered stations and the scenarios were consistent in predicting increasing trend of maximum-minimum temperature and decreasing trend of precipitations. RCP8.5 scenario shows the worst trend of precipitation and temperature. Keywords Statistical downscaling . Projections . Precipitation . Temperature . Iraq
Introduction Due to human interventions and the use of fossil fuels, the greenhouse gas concentration in the atmosphere has increased and resulted in a global energy disparity (Wentz et al. 2007; Chu et al. 2010; Huang et al. 2011). This in turn has led to what is called climate changes. Change in the climate means a state within a certain period where the statistical distribution of weather patterns is changeable due to the radiative forcing (RF) variations (Al-Mukhtar 2018; Moussa et al. 2018). The sources of these variations arise from the natural, anthropogenic, and
* Mustafa Al-Mukhtar [email protected] 1
Civil Engineering Department, University of Technology-Baghdad, Baghdad, Iraq
2
Department of Civil Engineering, Al-Kufa University, Najaf, Iraq
environmental process, which influence on the earth’s energy budget (Khadka and Pathak 2016). The RFs are embedding to the climate models as boundary conditions to simulate future sc
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