National Weather Forecasting and Climate Research Centre, Nigerian Meteorological Agency, Nnamdi Azikiwe International Airport, Abuja, PMB 615, Nigeria.
North Carolina A&T State University, Greensboro, NC, 27411, USA.
Environ Monit Assess. 2024 Mar 1;196(3):328. doi: 10.1007/s10661-024-12492-7.
We conducted an analysis of 16 historical simulations from the High-Resolution Model Intercomparison Project (HighResMIP) as part of the Coupled Model Intercomparison Project (CMIP) phase 6 (CMIP6). These simulations encompass both high- and low-resolution models and aim to investigate the impact of improved horizontal resolution on mean and extreme precipitation in West Africa between 1985 and 2014. Six Expert Team on Climate Change Detection and Indices (ETCCDI) were used to charactererize extreme indices. Bias adjustment was used to detect and adjust the biases in the models. Our observations indicate that the southeastern and southwestern regions of West Africa experience the most significant precipitation, which aligns with the simulations from HighResMIP. The enhanced horizontal resolution notably influences the simulation of orographically induced rainfall in elevated areas and intensifies precipitation in various aspects. When examining the highest 1-day precipitation, our observations reveal that most of the Guinea Coast region had 1-day rainfall exceeding 100 mm. However, this was overestimated and in some simulations underestimated by HighResMIP simulations. Furthermore, an increase in horizontal resolution appears to enhance the ability of high-resolution models to replicate the observed patterns of heavy precipitation (R10mm) and very heavy rainfall (R20mm) days. Spatial and temporal analysis suggests that uncertainty exists in the simulation of extreme precipitation in both high- and low-resolution simulations over West Africa. Also, bias adjustment shows a significant bias in the simulations. To address this issue, we employed a bias adjustment approach.
我们分析了耦合模式比较计划第六阶段（CMIP6）中高分辨率模式互比较计划（HighResMIP）的 16 个历史模拟结果。这些模拟涵盖了高分辨率和低分辨率模型，旨在研究在 1985 年至 2014 年期间，提高水平分辨率对西非平均和极端降水的影响。我们使用了六个气候变化检测和指数专家小组（ETCCDI）来描述极端指数。偏差调整用于检测和调整模型中的偏差。我们的观测结果表明，西非的东南和西南部地区经历了最显著的降水，这与 HighResMIP 的模拟结果一致。增强的水平分辨率显著影响了对地形引起的降雨的模拟，并在各个方面增强了降水。在检查最高的 1 天降水时，我们的观测结果显示，几内亚海岸地区的大部分地区 1 天的降雨量超过 100 毫米。然而，这一结果在 HighResMIP 的模拟中被高估了，在某些模拟中则被低估了。此外，水平分辨率的提高似乎增强了高分辨率模型复制观测到的强降水（R10mm）和特大暴雨（R20mm）日的能力。时空分析表明，在高分辨率和低分辨率模拟中，西非的极端降水模拟存在不确定性。此外，偏差调整显示模拟中存在显著偏差。为了解决这个问题，我们采用了偏差调整方法。
