Drought over East Asia Zhang, Lixia; Zhou, Tianjun
Journal of climate,
04/2015, Volume:
28, Issue:
8
Journal Article
Peer reviewed
Open access
East Asia is greatly impacted by drought. North and southwest China are the regions with the highest drought frequency and maximum duration. At the interannual time scale, drought in the eastern part ...of East Asia is mainly dominated by two teleconnection patterns (i.e., the Pacific–Japan and Silk Road teleconnections). The former is forced by SST anomalies in the western North Pacific and the tropical Indian Ocean during El Niño decaying year summers. The precipitation anomaly features a meridional tripolar or sandwich pattern. The latter is forced by Indian monsoon heating and is a propagation of stationary Rossby waves along the Asian jet in the upper troposphere. It can significantly influence the precipitation over north China. Regarding the long-term trend, there exists an increasing drought trend over central parts of northern China and a decreasing tendency over northwestern China from the 1950s to the present. The increased drought in north China results from a weakened tendency of summer monsoons, which is mainly driven by the phase transition of the Pacific decadal oscillation. East Asian summer precipitation is poorly simulated and predicted by current state-of-the-art climate models. Encouragingly, the predictability of atmospheric circulation is high because of the forcing of ENSO and the associated teleconnection patterns. Under the SRES A1B scenario and doubled CO₂ simulations, most climate models project an increasing drought frequency and intensity over southeastern Asia. Nevertheless, uncertainties exist in the projections as a result of the selection of climate models and the choice of drought index.
This paper explores the linguistic features of ancient and modern Chinese, focuses on capturing the knowledge of the relevant domains of ancient and contemporary Chinese using semantic models, and ...carries out the corresponding semantic resource extraction and semantic representation through the resource expression mechanism in the framework of the Semantic Association Network Model (SANM), and then analyzes the historical evolution of the lexicalization patterns of the Chinese language and the linguistic features of the Chinese language in different periods. In the historical evolution of Chinese lexicalization patterns, it is found that the distribution of lexicalization patterns of ancient Chinese table-cutting action lexical items is action+object > action+method > action result > action+tool, and the distribution of lexicalization patterns of modern Chinese table-cutting action lexical items is action+method > action+tool > action+result > action+object. The linguistic features of different periods show that all networks have small-world properties and scale-free properties, and the statistical parameters of the networks in each period are relatively close to each other, with the modern network having the most significant C (8.59) and the smallest L (0.92) and γ (0.40). Ancient and modern Chinese words and phrases with relational word collocations in the interval 0,23 have the most extensive and densest distribution of relational words. These data present the similarities and differences between linguistic features between ancient and modern Chinese, which is significant for studying ancient and modern Chinese.
The Paris Agreement set a goal to keep global warming well below 2 °C and pursue efforts to limit it to 1.5 °C. Understanding how 0.5 °C less warming reduces impacts and risks is key for climate ...policies. Here, we show that both areal and population exposures to dangerous extreme precipitation events (e.g., once in 10- and 20-year events) would increase consistently with warming in the populous global land monsoon regions based on Coupled Model Intercomparison Project Phase 5 multimodel projections. The 0.5 °C less warming would reduce areal and population exposures to once-in-20-year extreme precipitation events by 25% (18-41%) and 36% (22-46%), respectively. The avoided impacts are more remarkable for more intense extremes. Among the monsoon subregions, South Africa is the most impacted, followed by South Asia and East Asia. Our results improve the understanding of future vulnerability to, and risk of, climate extremes, which is paramount for mitigation and adaptation activities for the global monsoon region where nearly two-thirds of the world's population lives.
The Tibetan Plateau (TP) plays an essential role in the global hydrological cycle. Unlike the well‐recognized surface warming, changes in precipitation over the TP and the underlying mechanisms ...remain ambiguous. A significant increase in the amount of precipitation over the southeastern TP in May over 1979–2014 (13.46% decade−1 of the climatology) is identified in this study, based on homogenized daily rain gauge data. Both the increased precipitation frequency and intensity have contributions. The coherent increases in soil moisture content and vegetation activities further confirm the precipitation trend, indicating a wetting and greening TP in the early summer in recent decades. The moisture budget analysis shows that this wetting trend in the past four decades is dominated by the increased water vapor convergence due to circulation changes, while increases in specific humidity play a minor role. The wetting trend over the TP in May results directly from the earlier onset of the South Asian summer monsoon (ASM) since the late 1970s associated with the phase transition of Interdecadal Pacific Oscillation around the late 1990s. The earlier onset of the ASM triggers low‐level southwesterly anomalies over the northern Indian Ocean, promoting moisture convergence and increased precipitation over the TP in May. Specifically, the increased amount of precipitation after the onset of the ASM explains 95% of the increase in the total amount of precipitation in May.
Plain Language Summary
The amount of precipitation in May over the Tibetan Plateau (TP) has increased significantly since 1979. Both the increased precipitation frequency and intensity have contributions. The coherent increases in soil moisture content and vegetation activities further confirm the precipitation trend, indicating a wetting and greening TP in the early summer in recent decades. The moisture budget analysis shows that this wetting trend in the past four decades is dominated by the increased water vapor convergence due to circulation changes, while increases in specific humidity play a minor role. The wetting trend over the TP in May results directly from the earlier onset of the South Asian summer monsoon since the late 1970s, which is fundamentally triggered by the interdecadal variability of the Pacific Ocean.
Key Points
The amount, frequency, and intensity of precipitation in May over the Tibetan Plateau have increased significantly since 1979
Soil moisture content and vegetation activities in the early summer increased as a response to the wetting trend
The wetting trend in May is a direct result of earlier onset of South Asian summer monsoon associated with the phase transition of Interdecadal Pacific Oscillation
Changes in global land monsoon (GLM) precipitation determine the local water resource, affecting two thirds of global population. The future changes in GLM summer precipitation and the sources of ...projection uncertainty under four scenarios are investigated using the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. The GLM summer precipitation is projected to increase by 1.76 ± 1.57% (2.54 ± 2.22%), 1.33 ± 1.97% (3.52 ± 3.05%), 0.96 ± 2.04% (3.51 ± 4.97%), and 1.71 ± 2.38% (5.75 ± 5.92%) in the near (long) term under Shared Socioeconomic Pathway (SSP) 1–2.6, SSP2–4.5, SSP3–7.0, and SSP5–8.5, respectively. The enhancement is caused by thermodynamic responses due to increased moisture, which is partly offset by dynamic responses due to weakened circulation. The uncertainty in GLM precipitation projection is the largest in SSP5–8.5 long‐term projection. The uncertainty of submonsoon precipitation projections is larger than that in GLM precipitation. The uncertainty of monsoon precipitation projection arises from the circulation changes, which can be partly explained by model‐dependent response to uniform sea surface temperature warming.
Plain Language Summary
The changes of monsoon rainfall under a warmer climate receive much attention. Here we revealed the future changes of summer precipitation over global and submonsoon regions in different periods under four new scenarios designed by the Coupled Model Intercomparison Project Phase 6 (CMIP6). In 2021–2040 (2080–2099), the monsoon summer rainfall will increase by about 1.76 ± 1.57% (2.54 ± 2.22%), 1.33 ± 1.97% (3.52 ± 3.05%), 0.96 ± 2.04% (3.51 ± 4.97%), and 1.71 ± 2.38% (5.75 ± 5.92%) under the low, medium, and two high emission scenarios, respectively. At the end of the 21st century, the monsoon rainfall will increase largest in the highest emission scenario with largest spread. Moreover, the spread over each submonsoon region is much larger than that of global land monsoon. The increase of rainfall is associated with the increase of water vapor but offset by the weakened circulation. The spread of rainfall changes is caused by the spread of circulation projection, which is partly caused by the model‐dependent responses of circulation to uniform sea surface temperature warming.
Key Points
Global land monsoon precipitation increase is due to moisture increases, while the uncertainty is due to uncertainty of circulation changes
The uncertainty of circulation mainly comes from model spread in midterm and long‐term projections but from internal variability in near term
Model‐dependent response to uniform sea surface temperature warming is one of the uncertainty sources in land monsoon circulation projection
Extreme high‐temperature events have large socioeconomic and human health impacts. East Asia (EA) is a populous region, and it is crucial to assess the changes in extreme high‐temperature events in ...this region under different climate change scenarios. The Community Earth System Model low‐warming experiment data were applied to investigate the changes in the mean and extreme high temperatures in EA under 1.5°C and 2°C warming conditions above preindustrial levels. The results show that the magnitude of warming in EA is approximately 0.2°C higher than the global mean. Most populous subregions, including eastern China, the Korean Peninsula, and Japan, will see more intense, more frequent, and longer‐lasting extreme temperature events under 1.5°C and 2°C warming. The 0.5°C lower warming will help avoid 35%–46% of the increases in extreme high‐temperature events in terms of intensity, frequency, and duration in EA with maximal avoidance values (37%–49%) occurring in Mongolia. Thus, it is beneficial for EA to limit the warming target to 1.5°C rather than 2°C.
Plain Language Summary
Extreme heats continue to occur as global warming continues in the last several decades. These natural disasters can lead to illnesses and deaths of people and animals and great economic losses. The Paris Agreement called for limiting the global warming bellow 2°C and pursuing efforts to limit it to 1.5°C compared with preindustrial levels. We used a set of simulations to investigate the changes of the mean temperature and extreme heats in 1.5°C and 2°C warmer climates in East Asia and the benefits of limiting global warming to 1.5°C rather than 2°C. We find that the mean warming of East Asia is about 0.2°C higher than global mean. Most densely populated subregions, including eastern China, the Korean Peninsula, and Japan, will see larger extreme heats increase than the other subregions of East Asia. Compared with the 2°C warming climate, the increasing of extreme heats will be reduced over one third in the 1.5°C warming climate.
Key Points
Changes in the mean and extreme high temperatures over East Asia in response to warmings of 1.5°C and 2°C were quantified using the recently released NCAR CESM low‐warming experiment data
Most densely populated subregions, including eastern China, the Korean Peninsula, and Japan, will see larger increases in extreme high‐temperature events than the other subregions of East Asia in terms of intensity, frequency, and duration under 1.5°C and 2°C warming
The 0.5°C lower warming will help avoid 35%‐46% of the increases in the frequency, intensity, and duration of extreme high‐temperature events in East Asia with maximal avoidance values (37%‐49%) occurring in Mongolia
To elucidate the sequence, origin and structure-activity relationship of antioxidant peptides from sesame protein, sesame protein was hydrolysed by a dual-enzyme system comprised alcalase and ...trypsin, then this hydrolysate was fractionated by ultrafiltration and preparative HPLC. Subsequently, peptides in the high antioxidant activity fraction were identified by nano liquid chromatography-electrospray ionization-tandem mass spectrometry (Nano-LC-ESI-MS/MS), finally the structure-activity relationship of antioxidant peptide with the strongest activity in the sesame peptides was illustrated by comparative molecular field analysis (CoMFA). The results showed that seven novel antioxidant peptides were discovered, their sequences were as follows, RDRHQKIG, TDRHQKLR, MNDRVNQGE, RENIDKPSRA, SYPTECRMR, GGVPRSGEQEQQ and AGEQGFEYVTFR. The SYPTECRMR was the hydrolysate of 2S albumin, the others derived from 11S globulin. The SYPTECRMR whose IC50 Values of DPPH and ABTS were 0.105 mg/mL and 0.004 mg/mL respectively exhibited the highest antioxidant activity among the seven sesame peptides. The active site of SYPTECRMR tended to locate on Cys6 and Met8. A positive correlation between Cys6, Met8, the bulky C-terminal amino acid residue (Arg9), the negative charged group around sulphur-containing amino acids and the antioxidant activity of SYPTECRMR was observed from the CoMFA model. The results presented herein suggested that sesame protein hydrolysates have potential applications in functional food due to their high antioxidant activity, the CoMFA model could provide insight into the structure-activity relationship of antioxidant peptide, which is useful to screen, identify and design the novel antioxidant peptide.
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•Seven antioxidant peptides are identified from sesame protein hydrolysis by Nano-LC-ESI-MS/MS.•Antioxidant peptide SYPTECRMR arises from 2S albumin, the others come from 11S globulin.•SYPTECRMR shows the strongest antioxidant activity among sesame peptides.•Sulphur-containing amino acids, steric and electrostatic factors dominate the antioxidant activity of SYPTECRMR.
Quantifying source apportionment of potentially toxic elements (PTEs) in soils and associated human health risk (HHR) is essential for soil environment regulation and pollution risk mitigation. For ...this purpose, an integrated method was proposed, and applied to a dataset consisting of As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn in 273 soil surface samples. Positive matrix factorization (PMF) was used to quantitatively examine sources contributions of PTEs in soils; and the HHR arising from the identified source was determined by combining source profiles and health risk assessment; at last, sequential Gaussian simulation (SGS) was used to identify the areas with high HHR. Four sources were identified by PMF. Natural and agricultural sources affected all 9 PTEs contents with contributions ranging from 19.2% to 62.9%. 41.9% of Cd, 40.8% of Pb, 58.6% of Se, and 29.8% of Zn were controlled by industrial and traffic emissions. Metals smelting and mining explained 35.5%, 30.5%, and 24.9% of Cr, Cu, and Ni variations, respectively. Hg was dominated by atmospheric deposition from coal combustion and coking (58.7%). The mean values of the total non-carcinogenic risks of PTEs were 1.55 × 10−1 and 9.40 × 10−1 for adults and children, and the total carcinogenic risk of PTEs had an average value of 8.86 × 10−5. Based on source-oriented HHR calculation, natural and agricultural sources were the most important factor influencing HHR, explaining 51.0% and 49.1% of non-carcinogenic risks for children and adults, and 44.2% of carcinogenic risk. SGS indicated that 1.1% of the total area was identified as hazardous areas with non-carcinogens risk for children.
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•Positive matrix factorization was used to obtain potentially toxic elements sources.•Exposure risk model was used to calculate health risk of potentially toxic elements.•Geostatistics was applied to determine hazardous area with health risk.•Significant human influence was identified on all 9 potentially toxic elements.•Non-carcinogenic risk of potentially toxic elements was found for children.
Increasing evidences have shown that resveratrol could protect the brain from ischemic injury; the mechanisms underlying its neuroprotective effects are multifactorial and not fully understood. It ...remains unclear whether resveratrol could exert neuroprotection through modulating gut-brain axis, which plays important roles in stroke pathology. In this study, C57BL/6 mice underwent middle cerebral artery occlusion (60 min) followed by reperfusion for 3 days. Resveratrol, when applied immediately after MCAO onset for 3 days, promoted Th1/Th2 balance towards Th2 polarization and skewed Treg/Th17 balance towards Treg in the small intestinal lamina propria (SI-LP), and decreased small intestinal pro-inflammatory cytokines expression through modulating intestinal flora at 3 days post-ischemia (dpi). Resveratrol attenuated cerebral ischemia-induced increase in the epithelial and vascular permeability of small intestine as evidenced by reduced evans blue extravasasion and decreased protein leakage by feces/plasma albumin ratio at 3 dpi. The blood levels of pro-inflammatory cytokines at 3 dpi were also attenuated by resveratrol due to inhibiting intestinal pro-inflammatory immunity and decreasing epithelial and vascular permeability. Resveratrol robustly protected against post-stroke inflammation-induced blood–brain barrier disruption not only in the cortex but also in the striatum at 3 dpi. Furthermore, resveratrol mediated smaller cerebral infarcts and less neurological deficits via decreasing the levels of pro-inflammatory cytokines in the peri-infarct area at 3 dpi. Our results for the first time demonstrated that resveratrol may inhibit systemic post-stroke inflammation and neuroinflammation via modulating intestinal flora-mediated Th17/Tregs and Th1/Th2 polarity shift in SI-LP, which may be one of the mechanisms underlying the neuroprotective effects of resveratrol.
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