| 1. |
- Iyakaremye, Vedaste, et al.
(author)
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Increased high-temperature extremes and associated population exposure in Africa by the mid-21st century
- 2021
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 790
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Journal article (peer-reviewed)abstract
- Previous studies warned that heat extremes are likely to intensify and frequently occur in the future due to climate change. Apart from changing climate, the population's size and distribution contribute to the total changes in the population exposed to heat extremes. The present study uses the ensemble mean of global climate models from the Coupled Model Inter-comparison Project Phase six (CMIP6) and population projection to assess the future changes in high-temperature extremes and exposure to the population by the middle of this century (2041–2060) in Africa compared to the recent climate taken from 1991 to 2010. Two Shared Socioeconomic Pathways (SSPs), namely SSP2-4.5 and SSP5-8.5, are used. Changes in population exposure and its contributors are quantified at continental and for various sub-regions. The intensity of high-temperature extremes is anticipated to escalate between 0.25 to 1.8 °C and 0.6 to 4 °C under SSP2-4.5 and SSP5-8.5, respectively, with Sahara and West Southern Africa projected to warm faster than the rest of the regions. On average, warm days' frequency is also expected to upsurge under SSP2-4.5 (26–59%) and SSP5-8.5 (30–69%) relative to the recent climate. By the mid-21st century, continental population exposure is expected to upsurge by ~25% (28%) of the reference period under SSP2-4.5|SSP2 (SSP5-8.5|SSP5). The highest increase in exposure is expected in most parts of West Africa (WAF), followed by East Africa. The projected changes in continental exposure (~353.6 million person-days under SSP2-4.5|SSP2 and ~401.4 million person-days under SSP5-8.5|SSP5) are mainly due to the interaction effect. However, the climate's influence is more than the population, especially for WAF, South-East Africa and East Southern Africa. The study findings are vital for climate change adaptation.
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| 2. |
- Yang, Xiaoye, 1996, et al.
(author)
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Enhanced spring warming of the Tibetan Plateau amplifies summer heat stress in Eastern Europe
- 2024
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In: Climate Dynamics. - 0930-7575 .- 1432-0894.
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Journal article (peer-reviewed)abstract
- The Tibetan Plateau (TP), often referred to as the “Roof of the World”, has experienced rapid warming in recent decades. This warming has had significant impacts on downstream regions, while its effects on upstream regions are less well-defined. This study explores the relationship between TP warming and the occurrence of summer heat stress days in Europe, with a particular focus on Eastern Europe (EEU). Our analysis reveals a robust correlation between TP warming in both the summer and the preceding spring, and the frequency of heat stress days in EEU, demonstrating a significant interannual connection. During the spring, pronounced warming in the southern TP generates a strong local Rossby wave source, triggering a substantial divergence anomaly that amplifies the warming effect. This mechanism weakens the subtropical jet and strengthens the polar jet during the summer, setting the stage for anticyclonic anomalies over EEU. Furthermore, anomalies induced by TP warming, characterized by local upward movement and divergence at upper levels, intensify convergence and sinking airflow in the upstream region, leading to increased adiabatic heating in EEU. The dynamic response of the summer circulation anomaly, exemplified by the anticyclone anomaly over EEU, to prior TP warming is further corroborated through numerical simulations.
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| 3. |
- Yang, Xiaoye, 1996, et al.
(author)
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Interdecadal variation of winter cold surge path in east Asia and its relationship with arctic sea ice
- 2020
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In: Journal of Climate. - 0894-8755. ; 33, s. 4907-4925
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Journal article (peer-reviewed)abstract
- The paths of winter cold surge (CS) events in East Asia (EA) from 1979 to 2017 are tracked by the Flexible Particle (FLEXPART) model using ERA-Interim daily datasets, and the probability density distribution of the paths is calculated by the kernel density estimation (KDE) method. The results showed that the paths of CSs are significantly correlated with the intensity of the CSs, which shows an interdecadal transition from weak to strong around 1995. CS paths can be classified into two types, namely, the western path type and the northern path type, which were more likely to occur before and after 1995, respectively. Before 1995, the cold air mainly originated from Europe and moved from west to east, and the synoptic features were associated with the zonal wave train. After 1995, cold air accumulated over western Siberia and then invaded EA along the northern path, and the synoptic features were mainly associated with the blocking structure. The geopotential height (GPH) anomalies over the Arctic were abnormally strong. This paper further analyzes the relationship between CSs and winter sea ice concentration (SIC) in the Arctic. The results show that the intensity of CSs is negatively correlated with the Barents SIC (BSIC). When the BSIC declines, the upward wave flux over the Barents Sea is enhanced and expanded to the midlatitude region. GPH anomalies over the Arctic are positive and form a negative AO-like pattern, which is conducive to the formation of the northern path CS. Furthermore, the observed results are supported by numerical experiments with the NCAR Community Atmosphere Model, version 5.3 (CAM5.3).
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