XML Persian Abstract Print


Abstract:  
Extended Abstract
Introduction: Global Climate Models (GCMs) are designed to assess climate change. These models are only able to simulate large-scale atmospheric circulation model data. Therefore, it is necessary to downscale the results of these models. There are different downscaling methods such as dynamical and statistical downscaling methods. To achieve a perspective of the future climate of the study area with the least uncertainty, the use of only one downscaling model does not seem logical. Therefore, in this study, two downscaling models of LARS-WG and Change Factor (Delta) were used and their results were compared.
The main purpose of this study is to investigate the effect of climate change on temperature, precipitation parameters and drought during 2050-2031 and 2070-2051 in Khatam city using two general circulations model namely BNU-ESM and HadGEM2 and two downscaling models namely Delta and LARS-WG under RCP2.6, RCP4.5 and RCP8.5
Material and methods: The Khatam city is located in the south of Yazd province, Iran. In this study, the data achieved from the synoptic station of Marvast were applied. The historical data from 1996 to 2017 comprised the daily temperature and precipitation. In the present study, the data of two large-scale models including HadGEM2-ES and BNU-ESM, as well as, two statistical downscaling methods of LARS-WG and Change Factor (CF) were applied to simulate precipitation and temperature variables and drought in Khatam city under three scenarios RCP2.6, RCP4.5 and RCP8.5 during the two periods of 2031-2050 and 2051-2070. Also, statistical indices such as R2, RMSE and NSE were used to evaluate the accuracy of CF method and LARS-WG model. To assess the drought in the baseline period (1996-2017) and two future periods, the standardized precipitation index (SPI) on a 24-month scale has been used.
Results: The results of temperature variations during the two periods of 2031 to 2050 and 2051 to 2070 indicated that this city has affected by global warming, so that based on the LARS-WG model, temperature changes indicate an increase of 1.75, 1.94 and 2.12 °C during 2031 to 2050 period and an increase of 2.07, 2.71 and 3.87 °C during 2051 to 2070 period under the scenarios of RCP2.6, RCP4.5 and RCP8, respectively. The results of annual precipitation variations based on the LARS-WG model showed that precipitation will decrease by 6.1, 14.2 and 35.2% during 2030 to 2051 and by 26.8%, 35.5 and 51.5% during 2051 to 2070 under RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively. Also, investigating annual temperature and precipitation changes based on the BNU-ESM model indicated a temperature increase by 1.06, 1.83 and 2.13 ° C during 2031 to 2050 period and a temperature increase by 1.084, 1.94 and 2.82 °C during 2051 to 2070 period under the scenarios of RCP2.6, RCP4.5 and RCP8, respectively. The results of annual precipitation variations based on the BNU-ESM model showed that precipitation will decrease by 14, 22.1 and 32.9% during 2030 to 2051 and by 24.2%, 33.9 and 48.1% during 2051 to 2070 under RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively. After determining the climatic parameters for future periods, the SPI values for future periods and three scenarios can be determined. The results showed the increase of meteorological drought for the HadGEM2 and BNU-ESM models in two future periods under all scenarios compared with the baseline period. The BNU-ESM showed higher drought compared to the HadGEM2 model.
Discussion and conclusion: According to the results, both downscaling models used in this study had the high accuracy in predicting precipitation and temperature in the future period, which is compatible with the results of Sadidi et al. (2020) in Kerman province and Panahi and Khorramabadi (2020) in East Azerbaijan province. The results of temperature changes during two future periods for both models indicated that the Khatam city has affected by global warming, so that temperature changes indicate an increase in temperature during 2031 to 2050 and 2051 to 2070 under RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively. Also, the study of precipitation changes for both models showed the decrease in precipitation during 2031 to 2050 and 2051 to 2070 under RCP2.6, RCP4.5 and RCP8.5 scenarios, respectively, so that the greatest decrease has occurred under RCP 8.5 scenario that is in accordance with the results of Givati et al. (2019) in the upstream of the Jordan River. The results of this study indicated the possibility of more severe droughts in future simulated periods by the LARS-WG downscaling model and CF method, that is compatible with the results of Lucas and Et al. (2008), Lebedzki (2006) and Saleh Pourjam et al. (2014). The increase in the severity of drought in future periods is due to the increase in temperature and decrease in precipitation, which is also confirmed by the results of Node Farahani et al. (2015). According to the results, between the two GCM models, the BNU-ESM model predicts the lowest precipitation, the highest temperature and the highest number of years with severe drought compared to the HadGEM2 model.
     
Type of Study: Research | Subject: Climate change
Received: 2020/12/6 | Accepted: 2021/03/14

Send email to the article author


Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

© 2021 CC BY-NC 4.0 | Desert Ecosystem Engineering Journal

Designed & Developed by : Yektaweb