| 11. |
- Ren, Zhihui, et al.
(författare)
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Temporal Scaling Characteristics of Sub-Daily Precipitation in Qinghai-Tibet Plateau
- 2024
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Ingår i: EARTHS FUTURE. - 2328-4277. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- The Qinghai-Tibet Plateau (QTP) is highly susceptible to destructive rainstorm hazards and related natural disasters. However, the lack of sub-daily precipitation observations in this region has hindered our understanding of rainstorm-related hazards and their societal impacts. To address this data gap, a new approach is devised to estimate sub-daily precipitation in QTP using daily precipitation data and geographical information. The approach involves establishing a statistical relationship between daily and sub-daily precipitation based on data from 102 observation sites. This process results in a set of functions with six associated parameters. These parameters are then modeled using local geographical and climatic information through a machine learning algorithm called support vector regression. The results indicated that the temporal scaling characteristics of sub-daily precipitation can be accurately described using a logarithmic function. The uncertainty of the estimates is quantified using the coefficient of variance and coefficient of skewness, which are estimated using a logarithmic and linear curve, respectively. Additionally, the six parameters are found to be closely linked to geographical conditions, enabling the creation of a 1-km parameters data set. This data set can be utilized to quantitatively describe the probabilistic distribution and extract key information about maximum precipitation duration (from 1 to 12 hr). Overall, the findings suggest that the generated parameters data set holds significant potential for various applications, including risk analysis, forecasting, and early warning for rainstorm-related natural disasters in QTP. The innovative method developed in this study proves to be an effective approach for estimating sub-daily precipitation and assessing its uncertainty in ungauged regions. As one of famous hotspots for natural disaster studies on Earth, the Qinghai-Tibet Plateau (QTP) is highly vulnerable to destructive rainstorm hazard and related natural disasters, causing significant damage to property, infrastructure, agriculture, and resulting in extensive loss of life. Short-duration heavy precipitation at sub-daily scales is an important trigger for flash flood, debris flows and other disasters in QTP. However, it is a poorly gauged high mountain region, observed data for sub-daily precipitation is extremely limited. Although there have been several satellite products and reanalysis data for sub-daily precipitation in QTP, their quality has large bias and uncertainty compared to observations. It leaves a large data gap of sub-daily precipitation, hindering the studies of rainstorm-related natural disasters in the region. In this work, we develop a new strategy to quantify the temporal scaling characteristics of sub-daily precipitation, as a basis of temporal downscaling. Then we use the new strategy to generate a parameters data set, to fill the data gap of sub-daily precipitation in QTP. The parameters data set generated provides an effective way to estimate sub-daily precipitation and its uncertainty, which can effectively serve for the rainstorm-related natural disasters study in QTP. A high-resolution gridded parameters data set is generated to estimate sub-daily precipitation and its uncertainty in QTP The temporal scaling characteristics of sub-daily precipitation in QTP is well described by a logarithmic function Spatial heterogeneity in the temporal scaling characteristics of sub-daily precipitation in QTP is closely related to geographical conditions
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| 12. |
- Rockström, Johan, et al.
(författare)
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Identifying a Safe and Just Corridor for People and the Planet
- 2021
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Ingår i: Earth's Future. - 2328-4277. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Keeping the Earth system in a stable and resilient state, to safeguard Earth's life support systems while ensuring that Earth's benefits, risks, and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a safe and just corridor that meets these goals. Although safe and just Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.
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| 13. |
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| 15. |
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| 16. |
- Tian, Shangjie, et al.
(författare)
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Magnetic topological insulator MnBi6 Te10 with a zero-field ferromagnetic state and gapped Dirac surface states
- 2020
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Ingår i: Physical Review B. - 2469-9950. ; 102:3
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic topological insulators (TIs) with nontrivial topological electronic structure and broken time-reversal symmetry exhibit various exotic topological quantum phenomena. The realization of such exotic phenomena at high temperature is one of the central topics in this area. We reveal that MnBi6Te10 is a magnetic TI with an antiferromagnetic ground state below 10.8 K whose nontrivial topology is manifested by Dirac-like surface states. The ferromagnetic axion insulator state with Z4=2 emerges once spins are polarized at a field as low as 0.1 T, accompanied with saturated anomalous Hall resistivity up to 10 K. Such a ferromagnetic state is preserved even with an external field down to zero at 2 K. Theoretical calculations indicate that the few-layer ferromagnetic MnBi6Te10 is also topologically nontrivial with a nonzero Chern number. Angle-resolved photoemission spectroscopy experiments further reveal three types of Dirac surface states arising from different terminations on the cleavage surfaces, one of which has insulating behavior with an energy gap of ∼28 meV at the Dirac point. These outstanding features suggest that MnBi6Te10 is a promising system to realize various topological quantum effects at zero field and high temperature.
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| 17. |
- von Salzen, Knut, et al.
(författare)
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Clean air policies are key for successfully mitigating Arctic warming
- 2022
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Ingår i: Communications Earth & Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- A tighter integration of modeling frameworks for climate and air quality is urgently needed to assess the impacts of clean air policies on future Arctic and global climate. We combined a new model emulator and comprehensive emissions scenarios for air pollutants and greenhouse gases to assess climate and human health co-benefits of emissions reductions. Fossil fuel use is projected to rapidly decline in an increasingly sustainable world, resulting in far-reaching air quality benefits. Despite human health benefits, reductions in sulfur emissions in a more sustainable world could enhance Arctic warming by 0.8 °C in 2050 relative to the 1995–2014, thereby offsetting climate benefits of greenhouse gas reductions. Targeted and technically feasible emissions reduction opportunities exist for achieving simultaneous climate and human health co-benefits. It would be particularly beneficial to unlock a newly identified mitigation potential for carbon particulate matter, yielding Arctic climate benefits equivalent to those from carbon dioxide reductions by 2050.
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| 18. |
- Watts, Nick, et al.
(författare)
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The 2020 report of The Lancet Countdown on health and climate change : responding to converging crises
- 2021
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 397:10269, s. 129-170
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Forskningsöversikt (refereegranskat)abstract
- The Lancet Countdown is an international collaboration established to provide an independent, global monitoring system dedicated to tracking the emerging health profile of the changing climate.The 2020 report presents 43 indicators across five sections: climate change impacts, exposures, and vulnerabilities; adaptation, planning, and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. This report represents the findings and consensus of the 35 leading academic institutions and UN agencies that make up The Lancet Countdown, and draws on the expertise of climate scientists, geographers, engineers, experts in energy, food, and transport, economists, social, and political scientists, data scientists, public health professionals, and doctors.
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| 19. |
- Wu, Zhaofei, et al.
(författare)
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The sensitivity of ginkgo leaf unfolding to the temperature and photoperiod decreases with increasing elevation
- 2022
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923. ; 315
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Tidskriftsartikel (refereegranskat)abstract
- Climate change substantially affects plant phenology, resulting in earlier vegetation onset across temperate and boreal regions. Phenological shifts caused by warming may alter species interactions across trophic levels because of species-specific responses, and influence the reproductive success of dioecious species if the phenological sensitivity to warming (ST) differs between genders. We used twigs collected from male and female gingko trees at three elevations on Tianmu Mountain in eastern China. The twigs were cultivated in climate chambers to determine the effects of three temperatures (10, 15, and 20 °C) and two photoperiods (8 and 16 h). We observed slightly earlier leaf unfolding dates in male twigs (1 day), and a higher heat requirement (growing degree hours) for leaf unfolding in female (14,334 ± 588 °C) compared to male twigs (13,874 ± 551 °C). Similar responses to temperature (ST = 3.7 days °C−1), photoperiod and elevation were observed across genders. The long photoperiod treatment shortened the time to leaf unfolding by 9.1 days, but temperature and photoperiod effects on leaf unfolding differed significantly depending on the elevation of the donor trees. Specifically, ST was higher (4.17 days °C−1) and the photoperiod effect on ST was larger (decreased by 1.15 days °C−1) at the lowest elevation than at the higher elevations (ST = 3.26 days °C−1; decreased by 0.48 days °C−1). This may be related to environment-induced local adaptations and self-protection mechanisms of trees at high elevations to avoid frost damage. Our results indicate that the photoperiod and genetic adaptations to local environments influenced the warming-induced phenological responses in ginkgo, but these responses were generally similar between the genders. For a given species, individuals in different climates may exhibit different phenological responses to higher temperatures, with individuals in warmer regions likely becoming increasingly limited by the photoperiod as the climate warms further.
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| 20. |
- Xiong, Zhifang, et al.
(författare)
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Intensified aridity over the Indo-Pacific Warm Pool controlled by ice-sheet expansion during the Last Glacial Maximum
- 2022
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The magnitude, direction and cause of precipitation changes across the Indo-Pacific Warm Pool (IPWP) during the Last Glacial Maximum (LGM) remain elusive. In particular, it is still inconclusive whether tropical or extra-tropical factors controlled such precipitation changes. Determining the spatio-temporal distribution of precipitation in the IPWP during the LGM is a valid strategy to address this issue, but the existing precipitation records are dominantly from maritime continents and marginal seas, with few data from pelagic oceans. In order to fill this gap, we analyzed the oxygen isotopic compositions of single Ethmodiscus rex diatom frustules (δ18OE. rex) from a sediment core (WPD-03) consisting of laminated diatom mats (LDMs) in the eastern Philippine Sea (EPS). δ18OE. rex was controlled mainly by sea-surface salinity variation and, thus, can reflect open-ocean precipitation changes across the IPWP. Our precipitation proxy records, in combination with existing published data, reveal spatial patterns of precipitation change that indicate overall drying across the IPWP during the LGM. Based on a comparison of paleoclimatic records with modeling results, we propose that extra-tropical factors (ice-sheet size) controlled precipitation variability in the IPWP during the LGM through a combination of zonal shifts of ENSO and meridional migration of the ITCZ. Strong aridity during the LGM prevented formation of a subsurface barrier layer and, hence, allowed accessing of sufficient nutrients to surface waters, stimulating blooms of E. rex and subsequent formation of LDMs in the IPWP. These findings suggest an important role for high-latitude climate in the tropical hydrological cycle during the LGM.
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