Investigating the Relationship Between Water Vapor and Precipitation in Northern Africa

In this study, we investigated a relationship between integrated water vapor (IWV) and standardized precipitation index (SPI), focusing on historical drought events over the northern part of Africa from 1850 to 2014. Here, monthly data was obtained from two climate models of CMCC-ESM2 and CESM2, representative models in coupled model intercomparison project phase 6 (CMIP6). The IWV was standardized with the gamma distribution for various time intervals from 2 to 12 months, and the standardized IWV (IWVs) was compared with two established drought indicators, namely SPI-6 and SPI-12. We considered Pearson correlation coefficients for evaluating their relationship. As results of correlation analysis with SPI-6, Pearson correlation coefficients were larger than 0.74 from 2 to 4 months and lower than 0.41 from 9 to 12 months. However, the coefficients for SPI-12 with the time interval of 12 months were 0.82 and 0.71 for CMCC-ESM2 and CESM2, respectively, while showing negligible relationships with lower values than 0.21 from 2 to 4 months. It shows there are intra-seasonal and annual patterns in the relationship between IWV and SPIs. Further analysis of temporal patterns in IWV may lead to the potential for improved drought prediction.