Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly charact...Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly characterized by its green abaxial leaf blade,partly connate stipules,and densely patent strigose hairs on stems and potioles.The phylogenetic analysis based on rbc L,nrDNA and rbc L+nrDNA datasets,revealed that all individuals of B.nivea var.strigosa formed a monophyletic group.The conservation status of B.nivea var.strigosa is assessed as“Near Threatened”(NT)according to IUCN evaluation criteria.The discovery of this new variety is not only crucial for the taxonomy of ramie,but also provides reference for the exploration and utilization of ramie.展开更多
Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest v...Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process involved the conversion of rotational wind energy into divergent wind energy,which in turn converted kinetic energy back into available potential energy,thereby impeding the further development and maintenance of the southwest vortex.展开更多
Meteorological disasters are some of the most serious and costly natural disasters, which have larger effects on economic and social activity. Liuchun Lake is an ecotourism area in the southwest region of Zhejiang pro...Meteorological disasters are some of the most serious and costly natural disasters, which have larger effects on economic and social activity. Liuchun Lake is an ecotourism area in the southwest region of Zhejiang province, where also has experienced meteorological disasters including rainstorm and cold wave. Understanding the temporal-spatial characteristics of meteorological disasters is important for the local tourism and economic development. Based on the daily temperature and precipitation from 18 meteorological stations in the southwest of Zhejiang province during 1953-2022 and some statistical approaches, the temporal and spatial characteristics of meteorological disasters (Freezing, Rainstorm, Cold wave) are analyzed. The results indicate that 1) Rainstorm occurred frequently around the Liuchun lake, the frequency was about 8 times/a, it can also reach about 3 times/a in the other region. Freezing and cold wave (including strong cold wave and extremely cold wave) had the same spatial distribution as rainstorm, however, except for Liuchun lake, they occurred less than one time in the other regions;2) The trend of rainstorm had larger spatial difference, it increased in all the study area, but it increased more significantly around the study area than around Liuchun lake. Freezing was on the downtrend in the whole region, with 93.3% of the stations passed the 95% significant level. Cold wave also showed a declined trend, but it was insignificantly at most of the stations, only 33% of the stations passed the 90% significant level. Compared with cold wave, strong cold wave and extremely strong cold wave had weaker decline in all the regions. In general, from 1953 to 2022 rainstorm showed an increasing trend, it was the main meteorological disaster in the study area, cold wave displayed a decreasing trend, but it still occurred about 2 - 3 times/a in most regions.展开更多
Understanding how evolutionary pressures related to climate change have shaped the current genetic background of domestic animals is a fundamental pursuit of biology. Here, we generated wholegenome sequencing data fro...Understanding how evolutionary pressures related to climate change have shaped the current genetic background of domestic animals is a fundamental pursuit of biology. Here, we generated wholegenome sequencing data from native goat populations in Iraq and Pakistan. Combined with previously published data on modern, ancient(Late Neolithic to Medieval periods), and wild Capra species worldwide, we explored the genetic population structure, ancestry components, and signatures of natural positive selection in native goat populations in Southwest Asia(SWA). Results revealed that the genetic structure of SWA goats was deeply influenced by gene flow from the eastern Mediterranean during the Chalcolithic period, which may reflect adaptation to gradual warming and aridity in the region. Furthermore, comparative genomic analysis revealed adaptive introgression of the KITLG locus from the Nubian ibex(C. nubiana) into African and SWA goats. The frequency of the selected allele at this locus was significantly higher among goat populations located near northeastern Africa. These results provide new insights into the genetic composition and history of goat populations in the SWA region.展开更多
The margin of the Tibetan Plateau of Southwest China is one of the most seismically active regions of China and is the location of the China Seismic Experimental Site(CSES).Many studies have developed seismic velocity...The margin of the Tibetan Plateau of Southwest China is one of the most seismically active regions of China and is the location of the China Seismic Experimental Site(CSES).Many studies have developed seismic velocity models of Southwest China,but few have compared and evaluated these models which is important for further model improvement.Thus,we compared six published seismic shear-wave velocity models of Southwest China on absolute velocity and velocity perturbation patterns.The models are derived from different types of data(e.g.,surface waves from ambient noise and earthquakes,body-wave travel times,receiver functions) and inversion methods.We interpolated the models into a uniform horizontal grid(0.5° × 0.5°) and vertically sampled them at 5,10,20,30,40,and 60 km depths.We found significant differences between the six models.Then,we selected three of them that showed greater consistency for further comparison.Our further comparisons revealed systematic biases between models in absolute velocity that may be related to different data types.The perturbation pattern of the model is especially divergent in the shallow part,but more consistent in the deep part.We conducted synthetic and inversion tests to explore possible causes and our results imply that systematic differences between the data,differences in methods,and other factors may directly affect the model.Therefore,the Southwest China velocity model still has considerable room for improvement,and the impact of inconsistency between different data types on the model needs further research.Finally,we proposed a new reference shear-wave velocity model of Southwest China(SwCM-S1.0) based on the three selected models with high consistency.We believe that this model is a better representation of more robust features of the models that are based on different data sets.展开更多
The prediction of precipitation at subseasonal to seasonal(S2S)timescales remains an enormous challenge because of the gap between weather and climate predictions.This study compares three deep learning algorithms,nam...The prediction of precipitation at subseasonal to seasonal(S2S)timescales remains an enormous challenge because of the gap between weather and climate predictions.This study compares three deep learning algorithms,namely,the long short-term memory recurrent(LSTM),gated recurrent unit(GRU),and recurrent neural network(RNN),and selects the optimal algorithm to establish an S2S precipitation prediction model.The models were evaluated in four subregions of the Sichuan Province:the Plateau,Valley,eastern Basin,and western Basin.The results showed that the RNN model had better performance than the LSTM and GRU models.This could be because the RNN model had an advantage over the LSTM model in the transformation of climate indices with positive and negative variations.In the validation of test datasets,the RNN model successfully predicted the precipitation trend in most years during the wet season(May-October).The RNN model had a lower prediction bias(within±10%),higher sign accuracy of the precipitation trend(~88.95%),and greater accuracy of the maximum precipitation month(>0.85).For the prediction of different lead times,the RNN model was able to provide a stable trend prediction for summer precipitation,and the time correlation coefficient score was higher than that of the National Climate Center of China.Furthermore,this study proposed a method to measure the sensitivity of the RNN model to different input features,which may provide unprecedented insights into the nonlinear relationship and complicated feedback process among climate systems.The results of the sensitivity distribution are as follows.First,the Niño 4 and Niño 3.4 indices were equally important for the prediction of wet season precipitation.Second,the sensitivity of the snow cover on the Tibetan Plateau was higher than that in the Northern Hemisphere.Third,an opposite sensitivity appeared in two different patterns of the Indian Ocean and sea ice concentrations in the Arctic and the Barents Sea.展开更多
Conodont animal is an extinct group of marine animals.The conodont elements and their hard skeletal remains are originally from the head region of this kind of animal,and they are considered to be functioned as“teeth...Conodont animal is an extinct group of marine animals.The conodont elements and their hard skeletal remains are originally from the head region of this kind of animal,and they are considered to be functioned as“teeth”.The“multielement apparatus”can also be called the“(conodont)apparatus”,“multimembrate(skeletal)apparatus”.展开更多
Background: Acute abdomen is one of the commonest reasons for presentation at the emergency department. The physiologic changes of pregnancy increase the chances of developing acute abdomen. The global incidence of ac...Background: Acute abdomen is one of the commonest reasons for presentation at the emergency department. The physiologic changes of pregnancy increase the chances of developing acute abdomen. The global incidence of acute abdomen in pregnancy range from 1 in 500 to 1 in 635 pregnant women. In 2018, a study in Azerbaijan reported a prevalence of 25%. However, to the best of our knowledge, very few studies have been carried out on this subject in Cameroon. Objectives: To determine the prevalence, assess the aetiologies, and review clinical profile of acute abdomen in pregnancy in the Southwest Cameroon. Methods: We conducted a 5-year retrospective study at the Obst/Gyn and Surgical units of Kumba, Buea, and Limbe Regional Hospitals. We included all files of pregnant women that were admitted for acute abdomen within the study period (1<sup>st</sup> Jan 2017 to 31<sup>st</sup> Dec 2021). Data was collected using a structured checklist adapted from previous studies. Descriptive statistics and statistical testing was done using SPSS version 25.0. Chi-square was used to compare categorical variables. p Results: Over 14,106 pregnant women were admitted to the aforementioned hospitals within the study period. 335 (2.4%) met our inclusion criteria. The patients’ age ranged from 17 to 43 years. The mean age was 27 years. Acute abdomen was more frequent (65%) in the first trimester. Ectopic pregnancy was the commonest obstetric aetiology while appendicitis was the commonest non obstetric surgical aetiology. Abdominal pain and tenderness were the most common presentation. Conclusion: The prevalence of acute abdomen in pregnancy in the Southwest Cameroon is 10 times higher than the global prevalence. Our study also confirmed the numerous aetiologies and varied clinical presentations of acute abdomen in pregnancy. Hence a wake-up call for primary care physicians.展开更多
Based on the daily precipitation from 17 meteorological stations in the southwest of Zhejiang from 1953 to 2022, 11 extreme precipitation indices were calculated, and the temporal-spatial characteristic of extreme pre...Based on the daily precipitation from 17 meteorological stations in the southwest of Zhejiang from 1953 to 2022, 11 extreme precipitation indices were calculated, and the temporal-spatial characteristic of extreme precipitation were analyzed. The results indicate that 1) Except for the number of consecutive dry days (CDD), all the other extreme precipitation indices had low values in the northeast of the study area and high value around Liuchun Lake;2) CDD had a decreasing trend in most part of study area, while the other indices were on the rise, especially at Suichang (SC) and Tonglu (TL) stations, the change was significant (p 0.05);3) The annual variation showed that CDD declined with the trend of 0.83 d/10a, however, all the other indices increased, especially after 2000, the increase was more obvious. In general, the extreme precipitation mount, the extreme precipitation days showed an increasing trend, drought was less likely to happen, and the possibility of heavy precipitation is less, however, at some individual station such as SC, heavy precipitation and storm is much more likely to occur.展开更多
The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previ...The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previous studies have shown that sulfides in the YHF formed during different mineralization episodes and the YHF has the greatest potential for the formation of large-scale seafloor massive sulfide deposits.However,the sulfide chronology and hydrothermal activity of the YHF remain poorly constrained.In this study,mineralogical analyses and 230Th/U dating were performed.Hydrothermal activity may start about(35.9±2.3)ka from the southwest part of the YHF and may cease about(708±81)a ago from the northeast part of the YHF.The 74 nonzero chronological data from hydrothermal sulfide samples provide the first quantitative characterization of the spatial and temporal history along the SWIR.Hydrothermal activity in the SWIR has been relatively active over the past20 ka.In contrast,between 40 ka and 100 ka,hydrothermal activity was relatively infrequently and short in duration.The maximum activity occurred at 15–11 ka,9–7 ka,6–0.2 ka.There was a slight positive correlation between the maximal age and estimated surface area or estimated tonnage.The minimum mass accumulation rate of YHF is about 278 t/a,which is higher than most HFs related to ultramafic systems.The ultraslow spreading SWIR has the greatest potential to form large-scale seafloor massive sulfides(SMS)deposits.The results of this study provide new insights into the metallogenic mechanism of hydrothermal sulfides along ultraslow-spreading ridges.展开更多
Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing fa...Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing factors and mechanisms of remote and local evaporation remain to be further investigated.Using clustering analysis and Hybrid Single-Particle Lagrangian Integrated Trajectory version 5 model,we analyze the contributions of remote moisture transport and local evaporation to summer precipitation in the ESWC and their causes.There are mainly five remote moisture channels in the ESWC,namely the Arabian Sea channel,Bay of Bengal channel,western Pacific channel,Northwest channel 1 and Northwest channel 2.Among the five channels,the western Pacific channel has the largest number of trajectories,while the Bay of Bengal channel has the largest contribution rate of specific humidity(33.33%)and moisture flux(33.14%).The amount of regional average precipitation is close to that of the precipitation caused by remote moisture transport,and both are considerably greater than the rainfall amount caused by local evaporation.However,on interannual time scales,precipitation recirculation rates are negatively correlated to regional average precipitation and precipitation caused by remote moisture transport but are consistent with that caused by local evaporation.An apparent"+-+"wave train can be found on the height anomaly field in East Asia,and the sea surface temperature anomalies are positive in the equatorial Middle-East Pacific,the South China Sea,the Bay of Bengal and the Arabian Sea.These phenomena cause southwest-northeast moisture transport with strong updrafts,thereby resulting in more precipitation in the ESWC.展开更多
Karst environmental issues have become one of the hot spots in contemporary international geological research. The same problem of water shortage is one of the hot spots of global concern. The peak-cluster depression ...Karst environmental issues have become one of the hot spots in contemporary international geological research. The same problem of water shortage is one of the hot spots of global concern. The peak-cluster depression basins in southwest of Guangxi is an important water connotation and ecological barrier areas in the Pearl River Basin of China. Thus, studying the spatial and temporal variations and the influencing factors of its water yield services is critical to achieve the sustainable development of water resources and ecological environmental protection in this region. As such, this paper uses the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model to assess the spatial and temporal variabilities of water yield services and its trends in the peak-cluster depression basins in southwest of Guangxi from 2000 to 2020. This work also integrates precipitation(Pre), reference evapotranspiration(ET), temperature(Tem), digital elevation model(DEM), slope, normalized difference vegetation index(NDVI), land use/land cover(LULC) and soil type to reveal the main factors that influence water yield services with the help of Geodetector. Results show that: 1) in time scale,the total annual water yield in the study area show a fluctuating and increasing trend from 2000 to 2020, with a growth rate of 7.3753 × 10^(8)m^(3)/yr, and its multi-year average water yield was 538.07 mm;2) in spatial pattern, with high yield areas mainly distributed in the south of the study area(mainly including Shangsi County, Pingxiang City, Ningming County, Longzhou County and Jingxi County), and low yield areas mainly distributed in Baise City and Nanning City;3) the dominant factor of water yield within karst and non-karst landforms is not necessarily controlled by precipitation, and the explanation degree of DEM factors in karst areas is significantly higher than that in non-karst areas;4) amongst the climatic factors, Pre, ET and Tem are dominant in the spatial pattern of region water yield capacity. among which Pre has the highest explanatory power for the spatial heterogeneity of annual water production, with q values above0.8, and each driver showed a significant interaction on the spatial distribution of water yield, with Pre exhibiting the strongest interaction with LULC.展开更多
利用多源观测资料及ERA5(ECMWF reanalysis version 5)再分析资料,从气候统计、天气分析及物理量诊断等角度,分析2023年8月2—4日黑龙江省东南部一次极端强降水过程。高空持续辐散、副热带高压和东北北部冷涡稳定少动、西南低空急流持...利用多源观测资料及ERA5(ECMWF reanalysis version 5)再分析资料,从气候统计、天气分析及物理量诊断等角度,分析2023年8月2—4日黑龙江省东南部一次极端强降水过程。高空持续辐散、副热带高压和东北北部冷涡稳定少动、西南低空急流持续水汽输送等有利条件是此次强降水过程持续时间较长的主要原因。该过程可分为两个阶段:第1阶段,经向水汽净收入层和大气饱和层深厚,大气层结为弱对流不稳定;中层受西北气流控制,低层西南急流发展、伴随弱低涡东移,形成水平风速辐合及系统性上升运动,产生大范围持续性降水;该阶段以层积混合云为主,降水效率高,个别时段伴有列车效应,造成极端小时降水量及较大累积降水量。第2阶段,经向水汽净收入集中在对流层低层,且中心强度较大,对流层低层暖湿、饱和,中高层干冷,大气具有较强对流不稳定;在中层槽和低层暖式切变的系统性抬升以及地形辐合抬升的共同作用下,局地有积云发展,引发短时强降水,降水强度分布不均。展开更多
文摘Boehmeria nivea var.strigosa Zeng Y.Wu&Y.Zhao,a new variety of B.nivea(Urticaceae)from Southwest China,is here described based on evidence from morphology and molecular phylogeny.This new variety is mainly characterized by its green abaxial leaf blade,partly connate stipules,and densely patent strigose hairs on stems and potioles.The phylogenetic analysis based on rbc L,nrDNA and rbc L+nrDNA datasets,revealed that all individuals of B.nivea var.strigosa formed a monophyletic group.The conservation status of B.nivea var.strigosa is assessed as“Near Threatened”(NT)according to IUCN evaluation criteria.The discovery of this new variety is not only crucial for the taxonomy of ramie,but also provides reference for the exploration and utilization of ramie.
基金Key Project of Joint Meteorological Fund of the National Natural Science Foundation of China (U2242202)Key Project of the National Natural Science Foundation of China (42030611)+1 种基金Innovative Development Special Project of China Meteorological Administration (CXFZ2023J016)Innovation Team Fund of Sichuan Provincial Meteorological Service (SCQXCX7D-202201)。
文摘Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process involved the conversion of rotational wind energy into divergent wind energy,which in turn converted kinetic energy back into available potential energy,thereby impeding the further development and maintenance of the southwest vortex.
文摘Meteorological disasters are some of the most serious and costly natural disasters, which have larger effects on economic and social activity. Liuchun Lake is an ecotourism area in the southwest region of Zhejiang province, where also has experienced meteorological disasters including rainstorm and cold wave. Understanding the temporal-spatial characteristics of meteorological disasters is important for the local tourism and economic development. Based on the daily temperature and precipitation from 18 meteorological stations in the southwest of Zhejiang province during 1953-2022 and some statistical approaches, the temporal and spatial characteristics of meteorological disasters (Freezing, Rainstorm, Cold wave) are analyzed. The results indicate that 1) Rainstorm occurred frequently around the Liuchun lake, the frequency was about 8 times/a, it can also reach about 3 times/a in the other region. Freezing and cold wave (including strong cold wave and extremely cold wave) had the same spatial distribution as rainstorm, however, except for Liuchun lake, they occurred less than one time in the other regions;2) The trend of rainstorm had larger spatial difference, it increased in all the study area, but it increased more significantly around the study area than around Liuchun lake. Freezing was on the downtrend in the whole region, with 93.3% of the stations passed the 95% significant level. Cold wave also showed a declined trend, but it was insignificantly at most of the stations, only 33% of the stations passed the 90% significant level. Compared with cold wave, strong cold wave and extremely strong cold wave had weaker decline in all the regions. In general, from 1953 to 2022 rainstorm showed an increasing trend, it was the main meteorological disaster in the study area, cold wave displayed a decreasing trend, but it still occurred about 2 - 3 times/a in most regions.
基金supported by the National Natural Science Foundation of China(32050410304,32002140,31822052,91431572381)National Thousand Youth Talents Plan to Y.J。
文摘Understanding how evolutionary pressures related to climate change have shaped the current genetic background of domestic animals is a fundamental pursuit of biology. Here, we generated wholegenome sequencing data from native goat populations in Iraq and Pakistan. Combined with previously published data on modern, ancient(Late Neolithic to Medieval periods), and wild Capra species worldwide, we explored the genetic population structure, ancestry components, and signatures of natural positive selection in native goat populations in Southwest Asia(SWA). Results revealed that the genetic structure of SWA goats was deeply influenced by gene flow from the eastern Mediterranean during the Chalcolithic period, which may reflect adaptation to gradual warming and aridity in the region. Furthermore, comparative genomic analysis revealed adaptive introgression of the KITLG locus from the Nubian ibex(C. nubiana) into African and SWA goats. The frequency of the selected allele at this locus was significantly higher among goat populations located near northeastern Africa. These results provide new insights into the genetic composition and history of goat populations in the SWA region.
基金supported by Open Fund from Sino Probe Laboratory (No. Sinoprobe Lab 202201)the National Natural Science Foundation of China (No. U1939204)the Special Fund of the Institute of Geophysics, China Earthquake Administration (No. DQJB21B32)
文摘The margin of the Tibetan Plateau of Southwest China is one of the most seismically active regions of China and is the location of the China Seismic Experimental Site(CSES).Many studies have developed seismic velocity models of Southwest China,but few have compared and evaluated these models which is important for further model improvement.Thus,we compared six published seismic shear-wave velocity models of Southwest China on absolute velocity and velocity perturbation patterns.The models are derived from different types of data(e.g.,surface waves from ambient noise and earthquakes,body-wave travel times,receiver functions) and inversion methods.We interpolated the models into a uniform horizontal grid(0.5° × 0.5°) and vertically sampled them at 5,10,20,30,40,and 60 km depths.We found significant differences between the six models.Then,we selected three of them that showed greater consistency for further comparison.Our further comparisons revealed systematic biases between models in absolute velocity that may be related to different data types.The perturbation pattern of the model is especially divergent in the shallow part,but more consistent in the deep part.We conducted synthetic and inversion tests to explore possible causes and our results imply that systematic differences between the data,differences in methods,and other factors may directly affect the model.Therefore,the Southwest China velocity model still has considerable room for improvement,and the impact of inconsistency between different data types on the model needs further research.Finally,we proposed a new reference shear-wave velocity model of Southwest China(SwCM-S1.0) based on the three selected models with high consistency.We believe that this model is a better representation of more robust features of the models that are based on different data sets.
基金the National Natural Science Foundation of China(Nos.U20A2097,42175042)the Natural Science Foundation of Sichuan(Nos.2022NSFSC1056,2023NSFSC0246)+3 种基金the China Scholarship Council(No.201908510031)the Plateau and Basin Rainstorm,Drought and Flood Key Laboratory of Sichuan Province(Nos.SCQXKJZD202102-6,SCQXKJYJXMS202102)the Innovation Team Fund of Southwest Regional Meteorological Center,China Meteorological Administration(No.XNQYCXTD202201)the Sichuan Science and Technology Program(No.2022YFS0544).
文摘The prediction of precipitation at subseasonal to seasonal(S2S)timescales remains an enormous challenge because of the gap between weather and climate predictions.This study compares three deep learning algorithms,namely,the long short-term memory recurrent(LSTM),gated recurrent unit(GRU),and recurrent neural network(RNN),and selects the optimal algorithm to establish an S2S precipitation prediction model.The models were evaluated in four subregions of the Sichuan Province:the Plateau,Valley,eastern Basin,and western Basin.The results showed that the RNN model had better performance than the LSTM and GRU models.This could be because the RNN model had an advantage over the LSTM model in the transformation of climate indices with positive and negative variations.In the validation of test datasets,the RNN model successfully predicted the precipitation trend in most years during the wet season(May-October).The RNN model had a lower prediction bias(within±10%),higher sign accuracy of the precipitation trend(~88.95%),and greater accuracy of the maximum precipitation month(>0.85).For the prediction of different lead times,the RNN model was able to provide a stable trend prediction for summer precipitation,and the time correlation coefficient score was higher than that of the National Climate Center of China.Furthermore,this study proposed a method to measure the sensitivity of the RNN model to different input features,which may provide unprecedented insights into the nonlinear relationship and complicated feedback process among climate systems.The results of the sensitivity distribution are as follows.First,the Niño 4 and Niño 3.4 indices were equally important for the prediction of wet season precipitation.Second,the sensitivity of the snow cover on the Tibetan Plateau was higher than that in the Northern Hemisphere.Third,an opposite sensitivity appeared in two different patterns of the Indian Ocean and sea ice concentrations in the Arctic and the Barents Sea.
文摘Conodont animal is an extinct group of marine animals.The conodont elements and their hard skeletal remains are originally from the head region of this kind of animal,and they are considered to be functioned as“teeth”.The“multielement apparatus”can also be called the“(conodont)apparatus”,“multimembrate(skeletal)apparatus”.
文摘Background: Acute abdomen is one of the commonest reasons for presentation at the emergency department. The physiologic changes of pregnancy increase the chances of developing acute abdomen. The global incidence of acute abdomen in pregnancy range from 1 in 500 to 1 in 635 pregnant women. In 2018, a study in Azerbaijan reported a prevalence of 25%. However, to the best of our knowledge, very few studies have been carried out on this subject in Cameroon. Objectives: To determine the prevalence, assess the aetiologies, and review clinical profile of acute abdomen in pregnancy in the Southwest Cameroon. Methods: We conducted a 5-year retrospective study at the Obst/Gyn and Surgical units of Kumba, Buea, and Limbe Regional Hospitals. We included all files of pregnant women that were admitted for acute abdomen within the study period (1<sup>st</sup> Jan 2017 to 31<sup>st</sup> Dec 2021). Data was collected using a structured checklist adapted from previous studies. Descriptive statistics and statistical testing was done using SPSS version 25.0. Chi-square was used to compare categorical variables. p Results: Over 14,106 pregnant women were admitted to the aforementioned hospitals within the study period. 335 (2.4%) met our inclusion criteria. The patients’ age ranged from 17 to 43 years. The mean age was 27 years. Acute abdomen was more frequent (65%) in the first trimester. Ectopic pregnancy was the commonest obstetric aetiology while appendicitis was the commonest non obstetric surgical aetiology. Abdominal pain and tenderness were the most common presentation. Conclusion: The prevalence of acute abdomen in pregnancy in the Southwest Cameroon is 10 times higher than the global prevalence. Our study also confirmed the numerous aetiologies and varied clinical presentations of acute abdomen in pregnancy. Hence a wake-up call for primary care physicians.
文摘Based on the daily precipitation from 17 meteorological stations in the southwest of Zhejiang from 1953 to 2022, 11 extreme precipitation indices were calculated, and the temporal-spatial characteristic of extreme precipitation were analyzed. The results indicate that 1) Except for the number of consecutive dry days (CDD), all the other extreme precipitation indices had low values in the northeast of the study area and high value around Liuchun Lake;2) CDD had a decreasing trend in most part of study area, while the other indices were on the rise, especially at Suichang (SC) and Tonglu (TL) stations, the change was significant (p 0.05);3) The annual variation showed that CDD declined with the trend of 0.83 d/10a, however, all the other indices increased, especially after 2000, the increase was more obvious. In general, the extreme precipitation mount, the extreme precipitation days showed an increasing trend, drought was less likely to happen, and the possibility of heavy precipitation is less, however, at some individual station such as SC, heavy precipitation and storm is much more likely to occur.
基金The National Key R&D Program of China under contract No.2022YFE0140200the National Natural Science Foundation of China under contract Nos 42127807 and 42006074+1 种基金the China Ocean Mineral Resources R&D Association Project under contract Nos DY135-S1-1-02 and DY135-S1-1-01the Macao Science and Technology Development Fund under contract No.FDCT-002/2018/A1。
文摘The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previous studies have shown that sulfides in the YHF formed during different mineralization episodes and the YHF has the greatest potential for the formation of large-scale seafloor massive sulfide deposits.However,the sulfide chronology and hydrothermal activity of the YHF remain poorly constrained.In this study,mineralogical analyses and 230Th/U dating were performed.Hydrothermal activity may start about(35.9±2.3)ka from the southwest part of the YHF and may cease about(708±81)a ago from the northeast part of the YHF.The 74 nonzero chronological data from hydrothermal sulfide samples provide the first quantitative characterization of the spatial and temporal history along the SWIR.Hydrothermal activity in the SWIR has been relatively active over the past20 ka.In contrast,between 40 ka and 100 ka,hydrothermal activity was relatively infrequently and short in duration.The maximum activity occurred at 15–11 ka,9–7 ka,6–0.2 ka.There was a slight positive correlation between the maximal age and estimated surface area or estimated tonnage.The minimum mass accumulation rate of YHF is about 278 t/a,which is higher than most HFs related to ultramafic systems.The ultraslow spreading SWIR has the greatest potential to form large-scale seafloor massive sulfides(SMS)deposits.The results of this study provide new insights into the metallogenic mechanism of hydrothermal sulfides along ultraslow-spreading ridges.
基金National Natural Science Foundation of China(41875111)Special program for innovation and development of China Meteorological Administration(CXFZ2022J031,CXFZ2021J018)National Natural Science Foundation of China(40975058)。
文摘Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing factors and mechanisms of remote and local evaporation remain to be further investigated.Using clustering analysis and Hybrid Single-Particle Lagrangian Integrated Trajectory version 5 model,we analyze the contributions of remote moisture transport and local evaporation to summer precipitation in the ESWC and their causes.There are mainly five remote moisture channels in the ESWC,namely the Arabian Sea channel,Bay of Bengal channel,western Pacific channel,Northwest channel 1 and Northwest channel 2.Among the five channels,the western Pacific channel has the largest number of trajectories,while the Bay of Bengal channel has the largest contribution rate of specific humidity(33.33%)and moisture flux(33.14%).The amount of regional average precipitation is close to that of the precipitation caused by remote moisture transport,and both are considerably greater than the rainfall amount caused by local evaporation.However,on interannual time scales,precipitation recirculation rates are negatively correlated to regional average precipitation and precipitation caused by remote moisture transport but are consistent with that caused by local evaporation.An apparent"+-+"wave train can be found on the height anomaly field in East Asia,and the sea surface temperature anomalies are positive in the equatorial Middle-East Pacific,the South China Sea,the Bay of Bengal and the Arabian Sea.These phenomena cause southwest-northeast moisture transport with strong updrafts,thereby resulting in more precipitation in the ESWC.
基金Under the auspices of National Natural Science Foundation of China (No. 42061020)Natural Science Foundation of Guangxi Zhuang Autonomous Region (No. 2018JJA150135)+3 种基金Guangxi Key Research and Development Program (No. AA18118038)Science and Technology Department of Guangxi Zhuang Autonomous Region (No. 2019AC20088)The Program of Improving the Basic Research Ability of Young and Middle-aged Teachers in Guangxi Universities (No. 2021KY0431)High Level Talent Introduction Project of Beibu Gulf University (No. 2019KYQD28)。
文摘Karst environmental issues have become one of the hot spots in contemporary international geological research. The same problem of water shortage is one of the hot spots of global concern. The peak-cluster depression basins in southwest of Guangxi is an important water connotation and ecological barrier areas in the Pearl River Basin of China. Thus, studying the spatial and temporal variations and the influencing factors of its water yield services is critical to achieve the sustainable development of water resources and ecological environmental protection in this region. As such, this paper uses the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST) model to assess the spatial and temporal variabilities of water yield services and its trends in the peak-cluster depression basins in southwest of Guangxi from 2000 to 2020. This work also integrates precipitation(Pre), reference evapotranspiration(ET), temperature(Tem), digital elevation model(DEM), slope, normalized difference vegetation index(NDVI), land use/land cover(LULC) and soil type to reveal the main factors that influence water yield services with the help of Geodetector. Results show that: 1) in time scale,the total annual water yield in the study area show a fluctuating and increasing trend from 2000 to 2020, with a growth rate of 7.3753 × 10^(8)m^(3)/yr, and its multi-year average water yield was 538.07 mm;2) in spatial pattern, with high yield areas mainly distributed in the south of the study area(mainly including Shangsi County, Pingxiang City, Ningming County, Longzhou County and Jingxi County), and low yield areas mainly distributed in Baise City and Nanning City;3) the dominant factor of water yield within karst and non-karst landforms is not necessarily controlled by precipitation, and the explanation degree of DEM factors in karst areas is significantly higher than that in non-karst areas;4) amongst the climatic factors, Pre, ET and Tem are dominant in the spatial pattern of region water yield capacity. among which Pre has the highest explanatory power for the spatial heterogeneity of annual water production, with q values above0.8, and each driver showed a significant interaction on the spatial distribution of water yield, with Pre exhibiting the strongest interaction with LULC.
文摘利用多源观测资料及ERA5(ECMWF reanalysis version 5)再分析资料,从气候统计、天气分析及物理量诊断等角度,分析2023年8月2—4日黑龙江省东南部一次极端强降水过程。高空持续辐散、副热带高压和东北北部冷涡稳定少动、西南低空急流持续水汽输送等有利条件是此次强降水过程持续时间较长的主要原因。该过程可分为两个阶段:第1阶段,经向水汽净收入层和大气饱和层深厚,大气层结为弱对流不稳定;中层受西北气流控制,低层西南急流发展、伴随弱低涡东移,形成水平风速辐合及系统性上升运动,产生大范围持续性降水;该阶段以层积混合云为主,降水效率高,个别时段伴有列车效应,造成极端小时降水量及较大累积降水量。第2阶段,经向水汽净收入集中在对流层低层,且中心强度较大,对流层低层暖湿、饱和,中高层干冷,大气具有较强对流不稳定;在中层槽和低层暖式切变的系统性抬升以及地形辐合抬升的共同作用下,局地有积云发展,引发短时强降水,降水强度分布不均。
基金the National Key Research and Development Program of China[grant number 2018YFA0606403]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA23090102]the National Natural Science Foundation of China[grant number 41822502].
基金supported by the Utah Agricultural Experiment StationUtah State University(approved as journal paper Number 9665)+1 种基金UAES Seed Grant,Water Initiative Extension Grant,the U.S.Department of Interior,Bureau of Reclamation[Grant No.R22AP00220]based upon work supported by the U.S.Geological Survey[Grant No.G21AP10623]through the Utah Center for Water Resources Research at the Utah Water Research Laboratory。