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| 33. |
- Bu, Lulei, 1997, et al.
(författare)
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Upstream Evaporation is the Key to Extreme Summertime Heat Stress in North China
- 2024
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Ingår i: EARTH SYSTEMS AND ENVIRONMENT. - 2509-9426 .- 2509-9434. ; 8, s. 437-447
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Tidskriftsartikel (refereegranskat)abstract
- Humidity plays a critical role in amplifying temperature impact, leading to reduced heat dissipation efficiency and severe heat stress in humans. In the specific context of North China, this study explored different sensitivities of extreme heat stress (measured by wet-bulb temperature, TW) to humidity and temperature, and analyzed the influence of upstream variables on extreme heat stress. It is found that in the past four decades, extreme heat stress in North China increased rapidly at a maximum rate of over 0.4 celcius/decade, accompanied by the influence of humidity on extreme heat stress surpasses that of temperature. Even slight fluctuations in humidity can result in substantial variations in heat stress levels, unlike equivalent changes in temperature. This study is the first to find that for extreme heat stress, changes in temperature can only increase TW by up to 0.5 celcius, while increase in humidity can increase TW by 3 celcius. Notably, both humidity and temperature begin to rise approximately three days prior to extreme days, coinciding with intensified humidity transport and temperature advection from the upstream region. This study is also the first to find that intensified humidity transport is primarily driven by remarkably high evaporation originating from the western extension of the Northwest Pacific Subtropical High, while the strengthened temperature advection stems from a north-south temperature gradient during extreme days. This mechanism, wherein upstream variables impact downstream conditions, holds significant value for accurate prediction and timely response strategies.
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| 34. |
- Burauskaite-Harju, Agne, et al.
(författare)
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Characterizing and visualizing spatio-temporal patterns in hourly precipitation records
- 2012
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer. - 0177-798X .- 1434-4483. ; 109:3-4, s. 333-343
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Tidskriftsartikel (refereegranskat)abstract
- We develop new techniques to summarize and visualize spatial patterns of coincidence in weather events such as more or less heavy precipitation at a network of meteorological stations. The cosine similarity measure, which has a simple probabilistic interpretation for vectors of binary data, is generalized to characterize spatial dependencies of events that may reach different stations with a variable time lag. More specifically, we reduce such patterns into three parameters (dominant time lag, maximum cross-similarity, and window-maximum similarity) that can easily be computed for each pair of stations in a network. Furthermore, we visualize such threeparameter summaries by using colour-coded maps of dependencies to a given reference station and distance-decay plots for the entire network. Applications to hourly precipitation data from a network of 93 stations in Sweden illustrate how this method can be used to explore spatial patterns in the temporal synchrony of precipitation events.
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| 35. |
- Bustamante, Mercedes, et al.
(författare)
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Ten new insights in climate science 2023
- 2023
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Ingår i: Global Sustainability. - : CAMBRIDGE UNIV PRESS. - 2059-4798. ; 7
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Forskningsöversikt (refereegranskat)abstract
- Non-technical summary We identify a set of essential recent advances in climate change research with high policy relevance, across natural and social sciences: (1) looming inevitability and implications of overshooting the 1.5 degrees C warming limit, (2) urgent need for a rapid and managed fossil fuel phase-out, (3) challenges for scaling carbon dioxide removal, (4) uncertainties regarding the future contribution of natural carbon sinks, (5) intertwinedness of the crises of biodiversity loss and climate change, (6) compound events, (7) mountain glacier loss, (8) human immobility in the face of climate risks, (9) adaptation justice, and (10) just transitions in food systems.Technical summary The Intergovernmental Panel on Climate Change Assessment Reports provides the scientific foundation for international climate negotiations and constitutes an unmatched resource for researchers. However, the assessment cycles take multiple years. As a contribution to cross- and interdisciplinary understanding of climate change across diverse research communities, we have streamlined an annual process to identify and synthesize significant research advances. We collected input from experts on various fields using an online questionnaire and prioritized a set of 10 key research insights with high policy relevance. This year, we focus on: (1) the looming overshoot of the 1.5 degrees C warming limit, (2) the urgency of fossil fuel phase-out, (3) challenges to scale-up carbon dioxide removal, (4) uncertainties regarding future natural carbon sinks, (5) the need for joint governance of biodiversity loss and climate change, (6) advances in understanding compound events, (7) accelerated mountain glacier loss, (8) human immobility amidst climate risks, (9) adaptation justice, and (10) just transitions in food systems. We present a succinct account of these insights, reflect on their policy implications, and offer an integrated set of policy-relevant messages. This science synthesis and science communication effort is also the basis for a policy report contributing to elevate climate science every year in time for the United Nations Climate Change Conference.Social media summary We highlight recent and policy-relevant advances in climate change research - with input from more than 200 experts.
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| 40. |
- Cai, Z., et al.
(författare)
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Amplified wintertime Barents Sea warming linked to intensified Barents oscillation
- 2022
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9318 .- 1748-9326. ; 17:4
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Tidskriftsartikel (refereegranskat)abstract
- In recent decades, the Barents Sea has warmed more than twice as fast as the rest of the Arctic in winter, but the exact causes behind this amplified warming remain unclear. In this study, we quantify the wintertime Barents Sea warming (BSW, for near-surface air temperature) with an average linear trend of 1.74 °C decade-1 and an interdecadal change around 2003 based on a surface energy budget analysis using the ERA5 reanalysis dataset from 1979-2019. Our analysis suggests that the interdecadal change in the wintertime near-surface air temperature is dominated by enhanced clear-sky downward longwave radiation (CDLW) associated with increased total column water vapor. Furthermore, it is found that a mode of atmospheric variability over the North Atlantic region known as the Barents oscillation (BO) strongly contributed to the BSW with a stepwise jump in 2003. Since 2003, the BO turned into a strengthened and positive phase, characteristic of anomalous high pressure over the North Atlantic and South of the Barents Sea, which promoted two branches of heat and moisture transport from southern Greenland along the Norwegian Sea and from the Eurasian continent to the Barents Sea. This enhanced the water vapor convergence over the Barents Sea, resulting in BSW through enhanced CDLW. Our results highlight the atmospheric circulation related to the BO as an emerging driver of the wintertime BSW through enhanced meridional atmospheric heat and moisture transport over the North Atlantic Ocean.
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