Jamali Z., Heidarizadi Z. FUTURE CHANGES IN DRY CONDITIONS USING STATISTICAL DOWNSCALING MODEL (SDSM) IN THE WESTERN REGION OF GORGAN PLAIN, IRAN // Arid Ecosystems. 2022. Vol. 28. № 4 (93). P. 4-12. | PDF
Climate indices are important tools to better understand the effects of climate change in future time periods. We collected the daily mean temperature and precipitation for the years 1961-1990 from Gorgan meteorological stations. Then, climate change scenarios were simulated for three future time intervals (2020s, 2050s and 2080s) under RCP 26, RCP 45 and RCP 85 emission scenarios using CANESM2 model. The De Martonne Aridity Index and Emberger Index change were calculated for the future time periods. Our analysis showed that based on the monthly De Martonne Aridity Index value range, April to October are arid months while the remaining months are semi-arid for RCP 26, RCP 45 and RCP 85 emission scenarios of CANESM2. This may be partly due to a decrease of precipitation with increasing temperature in April to October. Therefore, agricultural areas require irrigation during these times. During summer, humidity will decrease in all the three future time periods for RCP 26 and RCP 45 scenarios. The same is also true for RCP 85 scenario except June of 2020s during which humidity is expected to be constant. Overall, humidity is projected to increase in most of the months in the three future time periods for RCP 26, RCP 45 and RCP 85 emission scenarios. The projected Aridity index of Emberger values shows a trend similar to the De Martonne Aridity Index. The R2 indicate a high correlation between De Martonne and Emberger indices proving similar trend of the two indices for changes in all the three future time periods.
Keywords: Aridity indices, greenhouse gases, IPCC AR5.