Ashraf S. Zakey

Regional Climate Modeling for the Developing World: The ICTP RegCM3 and RegCNET

Regional climate models are important research tools available to scientists around the world, including in economically developing nations (EDNs). The Earth Systems Physics (ESP) group of the Abdus Salam International Centre for Theoretical Physics (ICTP) maintains and distributes a state-of-the-science regional climate model called the ICTP Regional Climate Model version 3 (RegCM3), which is currently being used by a large research community for a diverse range of climate-related studies. The RegCM3 is the central, but not only, tool of the ICTP-maintained Regional Climate Research Network (RegCNET) aimed at creating south–south and north–south scientific interactions on the topic of climate and associated impacts research and modeling. In this paper, RegCNET, RegCM3, and illustrative results from RegCM3 benchmark simulations applied over south Asia, Africa, and South America are presented. It is shown that RegCM3 performs reasonably well over these regions and is therefore useful for climate studies in...

The Regional Climate Change Hyper‐Matrix Framework

The accurate assessment of the potential impacts of climate change on societies and ecosystems requires regional and local-scale climate change information. This assessment is critical for the development of local, national, and international policies to mitigate and adapt to the threat of climate change. Characterizing uncertainties in regional climate change projections (RCCPs) is therefore crucial for making informed decisions based on quantitative risk analysis. However, information about fine-scale climate change and associated uncertainties is lacking due to the absence of a coordinating framework to improve the characterization of such uncertainties. Here we propose the inception of such a framework.

Correction to: The influence of two land-surface hydrology schemes on the regional climate of Africa using the RegCM4 model

The original version of this article unfortunately contained a mistake.

Study of aerosol direct and indirect effects and auto-conversion processes over the West African monsoon region using a regional climate model

This study assesses the direct and indirect effects of natural and anthropogenic aerosols (e.g., black carbon and sulfate) over West and Central Africa during the West African monsoon (WAM) period (June–July–August). We investigate the impacts of aerosols on the amount of cloudiness, the influences on the precipitation efficiency of clouds, and the associated radiative forcing (direct and indirect). Our study includes the implementation of three new formulations of auto-conversion parameterization [namely, the Beheng (BH), Tripoli and Cotton (TC) and Liu and Daum (R6) schemes] in RegCM4.4.1, besides the default model’s auto-conversion scheme (Kessler). Among the new schemes, BH reduces the precipitation wet bias by more than 50% over West Africa and achieves a bias reduction of around 25% over Central Africa. Results from detailed sensitivity experiments suggest a significant path forward in terms of addressing the long-standing issue of the characteristic wet bias in RegCM. In terms of aerosol-induced radiative forcing, the impact of the various schemes is found to vary considerably (ranging from −5 to −25 W m−2).摘要本研究评估了西非季风时段 (6 月-8 月) 非洲西部和中部地区自然和人为 (例如, 黑炭和硫酸盐) 气溶胶的直接和间接效应. 除了针对 RegCM 4.4.1 模式默认的 Kessler 云水自动转换方案进行评估外, 还比对了 Beheng(BH), Tripoli and Cotton (TC) 和 Liu and Daum (R6) 三种新的参数化方案. 通过比对这些方案, 分析了气溶胶对云量的影响, 对云的降水效率的影响及其相应的直接和间接辐射强迫. 在三种新的方案中, BH 方案明显减少了模拟结果中湿度的偏差, 在西非和中非区域的模拟偏差分别降低了 50%和 25%. 敏感性试验表明, 这一方案为解决 RegCM 模式一直存在的湿度偏差问题向前推进了一大步. 另外, 不同的参数化方案模拟的气溶胶辐射效应有很大差别, 在-5 至-25 W m-2浮动.