Drought is a recurring dry condition with below-normal precipitation and is often associated with warm temperatures or heatwaves. A drought event can develop slowly over several weeks or suddenly within days, commonly...Drought is a recurring dry condition with below-normal precipitation and is often associated with warm temperatures or heatwaves. A drought event can develop slowly over several weeks or suddenly within days, commonly under abnormal atmospheric conditions(e.g., quasi-stationary high-pressure systems), and can persist for weeks, months, or even years.展开更多
Dust storms are one of the most frequent meteorological disasters in China,endangering agricultural production,transportation,air quality,and the safety of people’s lives and property.Against the backdrop of climate ...Dust storms are one of the most frequent meteorological disasters in China,endangering agricultural production,transportation,air quality,and the safety of people’s lives and property.Against the backdrop of climate change,Mongolia’s contribution to China’s dust cannot be ignored in recent years.In this study,we used the Weather Research and Forecasting model coupled with Chemistry(WRF-Chem),along with dynamic dust sources and the HYSPLIT model,to analyze the contributions of different dust sources to dust concentrations in northern China in March and April 2023.The results show that the frequency of dust storms in 2023 was the highest observed in the past decade.Mongolia and the Taklimakan Desert were identified as two main dust sources contributing to northern China.Specifically,Mongolia contributed more than 42%of dust,while the Taklimakan Desert accounted for 26%.A cold high-pressure center,a cold front,and a Mongolian cyclone resulted in the transport of dust aerosols from Mongolia and the Taklimakan Desert to northern China,where they affected most parts of the region.Moreover,two machine learning methods[the XGBoost algorithm and the Synthetic Minority Oversampling Technique(SMOTE)]were used to forecast the dust storms in March 2023,based on ground observations and WRF-Chem simulations over East Asia.XGBoost-SMOTE performed well in predicting hourly PM10 concentrations in China in March 2023,with a mean absolute error of 33.8μg m−3 and RMSE of 54.2μg m−3.展开更多
Although Platycodon grandiflorum(Jacq.)A.DC.is a renowned medicine food homology plant,reports of excessive cadmium(Cd)levels are common,which affects its safety for clinical use and food consumption.To enable its Cd ...Although Platycodon grandiflorum(Jacq.)A.DC.is a renowned medicine food homology plant,reports of excessive cadmium(Cd)levels are common,which affects its safety for clinical use and food consumption.To enable its Cd levels to be regulated or reduced,it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant,in addition to its detoxification mechanisms.This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P.grandiflorum.The experimental results showed that Cd was mainly accumulated in the roots[predominantly in the cell wall(50.96%-61.42%)],and it was found primarily in hypomobile and hypotoxic forms.The proportion of Cd in the soluble fraction increased after Cd exposure,and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves,with a higher increase in oxalate Cd.Therefore,it is likely that root retention mechanisms,cell wall deposition,vacuole sequestration,and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P.grandiflorum.The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P.grandiflorum,and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.展开更多
This article reviews recent progress in semi-arid climate change research in China.Results indicate that the areas of semiarid regions have increased rapidly during recent years in China,with an increase of 33%during ...This article reviews recent progress in semi-arid climate change research in China.Results indicate that the areas of semiarid regions have increased rapidly during recent years in China,with an increase of 33%during 1994-2008 compared to 1948-62.Studies have found that the expansion rate of semi-arid areas over China is nearly 10 times higher than that of arid and sub-humid areas,and is mainly transformed from sub-humid/humid regions.Meanwhile,the greatest warming during the past 100 years has been observed over semi-arid regions in China,and mainly induced by radiatively forced processes.The intensity of the regional temperature response over semi-arid regions has been amplified by land-atmosphere interactions and human activities.The decadal climate variation in semi-arid regions is modulated by oceanic oscillations,which induce land-sea and north-south thermal contrasts and affect the intensities of westerlies,planetary waves and blocking frequencies.In addition,the drier climates in semi-arid regions across China are also associated with the weakened East Asian summer monsoon in recent years.Moreover,dust aerosols in semi-arid regions may have altered precipitation by affecting the local energy and hydrological cycles.Finally,semi-arid regions in China are projected to continuously expand in the 21st century,which will increase the risk of desertification in the near future.展开更多
The virus SARS-CoV2,which causes the Coronavirus disease COVID-19 has become a pandemic and has spread to every inhabited continent.Given the increasing caseload,there is an urgent need to augment clinical skills in o...The virus SARS-CoV2,which causes the Coronavirus disease COVID-19 has become a pandemic and has spread to every inhabited continent.Given the increasing caseload,there is an urgent need to augment clinical skills in order to identify from among the many mild cases the few that will progress to critical illness.We present a first step towards building an artificial intelligence(AI)framework,with predictive analytics(PA)capabilities applied to real patient data,to provide rapid clinical decision-making support.COVID-19 has presented a pressing need as a)clinicians are still developing clinical acumen given the disease’s novelty,and b)resource limitations in a rapidly expanding pandemic require difficult decisions relating to resource allocation.The objectives of this research are:(1)to algorithmically identify the combinations of clinical characteristics of COVID-19 that predict outcomes,and(2)to develop a tool with AI capabilities that will predict patients at risk for more severe illness on initial presentation.The predictive models learn from historical data to help predict specifically who will develop acute respiratory distress syndrome(ARDS),a severe outcome in COVID-19.Our experimental results based on two hospitals in Wenzhou,Zhejang,China identify features most predictive of ARDS in COVID-19 initial presentation which would not have stood out to clinicians.A mild increase in elevated alanine aminotransferase(ALT)(a liver enzyme)),a presence of myalgias(body aches),and an increase in hemoglobin,in this order,are the clinical features,on presentation,that are the most predictive.Those two centers’COVID-19 case series symptoms on initial presentation can help predict severe outcomes.Predictive models that learned from historical data of patients from two Chinese hospitals achieved 70%to 80%accuracy in predicting severe cases.展开更多
Three approaches,i.e.,the harmonic analysis(HA) technique,the thermal diffusion equation and correction(TDEC) method,and the calorimetric method used to estimate ground heat flux,are evaluated by using observations fr...Three approaches,i.e.,the harmonic analysis(HA) technique,the thermal diffusion equation and correction(TDEC) method,and the calorimetric method used to estimate ground heat flux,are evaluated by using observations from the Semi-Arid Climate and Environment Observatory of Lanzhou University(SACOL) in July,2008.The calorimetric method,which involves soil heat flux measurement with an HFP01SC self-calibrating heat flux plate buried at a depth of 5 cm and heat storage in the soil between the plate and the surface,is here called the ITHP approach.The results show good linear relationships between the soil heat fluxes measured with the HFP01SC heat flux plate and those calculated with the HA technique and the TDEC method,respectively,at a depth of 5 cm.The soil heat fluxes calculated with the latter two methods well follow the phase measured with the HFP01SC heat flux plate.The magnitudes of the soil heat flux calculated with the HA technique and the TDEC method are close to each other,and they are about 2 percent and 6 percent larger than the measured soil heat flux,respectively,which mainly occur during the nighttime.Moreover,the ground heat fluxes calculated with the TDEC method and the HA technique are highly correlated with each other(R2 = 0.97),and their difference is only about 1 percent.The TDEC-calculated ground heat flux also has a good linear relationship with the ITHP-calculated ground heat flux(R2 = 0.99),but their difference is larger(about 9 percent).Furthermore,compared to the HFP01SC direct measurements at a depth of 5 cm,the ground heat flux calculated with the HA technique,the TDEC method,and the ITHP approach can improve the surface energy budget closure by about 6 percent,7 percent,and 6 percent at SACOL site,respectively.Therefore,the contribution of ground heat flux to the surface energy budget is very important for the semi-arid grassland over the Loess Plateau in China.Using turbulent heat fluxes with common corrections,soil heat storage be-tween the surface and the heat flux plate can improve the surface energy budget closure by about 6 to 7 percent,resulting in a clo-sure of 82 to 83 percent at the SACOL site.展开更多
Previous studies have reported that, before or after occurrences of strong earthquakes, some low earth orbit satellites recorded ionospheric disturbances, including electromagnetic emissions and plasma fluctuations ov...Previous studies have reported that, before or after occurrences of strong earthquakes, some low earth orbit satellites recorded ionospheric disturbances, including electromagnetic emissions and plasma fluctuations over the epicenter region or its conjugate point.Theoretically speaking, due to some electromagnetic coupling effect, electromagnetic emissions from the earthquake preparation zone could propagate from the lithosphere to the atmosphere, and could reach the ionosphere, even up to the inner magnetosphere. This paper introduces the electric field detector(EFD) onboard the ZhangHeng-1 satellite(ZH-1). The EFD is designed to measure electric field fluctuations within the broad frequency range of DC to 3.5 MHz, divided into 4 channels: ULF(DC–16 Hz), ELF(6 Hz–2.2 kHz), VLF(1.8 kHz–20 kHz) and HF(18 kHz–3.5 MHz). The sampling rates of the channels are 125 Hz, 5 kHz, 50 kHz and 10 MHz, respectively. The EFD includes4 spherical probes mounted on a over 4.5 m boom and an electronic box inside the satellite module. The resolution of the EFD is 1μV·m-1·Hz-1/2 at frequencies from DC to 16 Hz, and the sensitivity is 0.1 μV·m-1·Hz-1/2 at frequencies from 6 Hz to 2.2 kHz, 0.05 μV·m-1·Hz-1/2 in the band 1.8 kHz to 20 kHz, and 0.1μV·m-1·Hz-1/2 from 20 kHz to 3.5 MHz. The dynamic range from DC to 20 kHz is over 120 dB, and over96 dB from 20 kHz to 3.5 MHz. The EFD has two observation modes: survey mode and burst mode. The survey mode concentrates primarily on electric field power density values; the burst mode provides high sampling rate waveform data. The detailed configuration of the EFD onboard the ZH-1 is also introduced in this paper. During the six months' orbit test phase, the EFD recorded a number of natural electromagnetic emissions. Preliminary analysis of these data suggests that the EFD performs well onboard the ZH-1 and is meeting the requirements of the scientific objectives of ZH-1.展开更多
Although atmospheric greenhouse gas concentrations continuously increased, there was relatively little change in global-averaged surface temperatures from 1998 to 2013, which is known as atmospheric warming slowdown. ...Although atmospheric greenhouse gas concentrations continuously increased, there was relatively little change in global-averaged surface temperatures from 1998 to 2013, which is known as atmospheric warming slowdown. For further understanding the mechanism involved, we explored the energy redistribution between the atmosphere and ocean in different latitudes and depths by using data analysis as well as simulations of a coupled atmosphere–ocean box model. The results revealed that, compared with observational changes of ocean heat content (OHC) associated with rapid warming, the OHC changes related to warming slowdown are relatively larger in multiple ocean basins, particularly in the deeper layer of the Atlantic. The coupled box model also showed that there is a larger increasing trend of OHC under the warming slowdown scenario than the rapid warming scenario. Particularly, during the warming slowdown period, the heat storage in the deeper ocean increases faster than the ocean heat uptake in the surface ocean. The simulations indicated that the warming patterns under the two scenarios are accompanied by distinct outgoing longwave radiation and atmospheric meridional heat transport, as well as other related processes, thus leading to different characteristics of ocean heat uptake. Due to the global energy balance, we suggest this slowdown has a tight relationship with the accelerated heat transport into the global ocean.展开更多
The CSES(China seismic electromagnetic satellite) was launched on February 2, 2018 in a circular polar orbit at an altitude of～507 km. One of the main objectives of CSES is to search for and characterize ionospheric ...The CSES(China seismic electromagnetic satellite) was launched on February 2, 2018 in a circular polar orbit at an altitude of～507 km. One of the main objectives of CSES is to search for and characterize ionospheric perturbations that can be associated with seismic activities, to better understand the generation mechanism of such perturbations. Its scientific payload can measure a broad frequency range of electromagnetic waves and some important plasma parameters. This paper is a first-hand study of unusual observations recorded by the CSES over seismic regions prior to four earthquakes with M >7.0 since the satellite's launch. CSES detectors measured irregularities near the epicenter of these four earthquakes. It is already clear that data from instruments onboard the CSES will be of significant help in studies of characteristics of ionospheric perturbations related to earthquakes and their generation mechanisms.展开更多
Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contai...Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contain the spread of COVID-19,resulting in a significant reduction of human activities.This event presents a convenient opportunity to study the impact of human activities in the transportation and industrial sectors on air pollution.Here,we investigate the variations in air quality attributed to the COVID-19 lockdown policy in the megacities of China by combining in-situ environmental and meteorological datasets,the Suomi-NPP/VIIRS and the CO_(2)emissions from the Carbon Monitor project.Our study shows that PM_(2.5)concentrations in the spring of 2020 decreased by 41.87%in the Yangtze River Delta(YRD)and 43.30%in the Pearl River Delta(PRD),respectively,owing to the significant shutdown of traffic and manufacturing industries.However,PM_(2.5)concentrations in the Beijing-Tianjin-Hebei(BTH)region only decreased by 2.01%because the energy and steel industries were not fully paused.In addition,unfavorable weather conditions contributed to further increases in the PM_(2.5)concentration.Furthermore,CO_(2)concentrations were not significantly affected in China during the short-term emission reduction,despite a 19.52%reduction in CO_(2)emissions compared to the same period in 2019.Our results suggest that concerted efforts from different emission sectors and effective long-term emission reduction strategies are necessary to control air pollution and CO_(2)emissions.展开更多
The China Seismo-Electromagnetic Satellite, launched into orbit from Jiuquan Satellite Launch Centre on February 2 nd, 2018, is China's first space satellite dedicated to geophysical exporation. The satellite carr...The China Seismo-Electromagnetic Satellite, launched into orbit from Jiuquan Satellite Launch Centre on February 2 nd, 2018, is China's first space satellite dedicated to geophysical exporation. The satellite carries eight scientific payloads including high-precision magnetometers to detect electromagnetic changes in space, in particular changes associated with global earthquake disasters. In order to encourage and facilitate use by geophysical scientists of data from the satellite's payloads, this paper introduces the application systems developed for the China Seismo-Electromagnetic Satellite by the Institute of Crustal Dynamics, China Earthquake Administration;these include platform construction, data classification, data storage, data format, and data access and acquisition.展开更多
The high energetic particle package(HEPP) on-board the China Seismo-Electromagnetic Satellite(CSES) was launched on February 2, 2018. This package includes three independent detectors: HEPP-H, HEPP-L, and HEPP-X. HEPP...The high energetic particle package(HEPP) on-board the China Seismo-Electromagnetic Satellite(CSES) was launched on February 2, 2018. This package includes three independent detectors: HEPP-H, HEPP-L, and HEPP-X. HEPP-H and HEPP-L can detect energetic electrons from 100 keV to approximately 50 MeV and protons from 2 MeV to approximately 200 MeV. HEPP-X can measure solar X-rays in the energy range from 1 keV to approximately 20 keV. The objective of the HEPP payload was to provide a survey of energetic particles with high energy, pitch angle, and time resolutions in order to gain new insight into the space radiation environments of the near-Earth system. Particularly, the HEPP can provide new measurements of the magnetic storm related precipitation of electrons in the slot region, and the dynamics of radiation belts. In this paper, the HEPP scientific data sets are described and initial results are provided.The scientific data can show variations in the flux of energetic particles during magnetic storms.展开更多
The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean...The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean and atmosphere(i.e.air-sea O_(2)flux),which is one of the major contributors to uncertainties in the O_(2)-based estimations of the carbon uptake.Here,we explore the variability of air-sea O_(2)flux with the use of outputs from Coupled Model Intercomparison Project phase 6(CMIP6).The simulated air-sea O_(2)flux exhibits an obvious warming-induced upward trend(~1.49 Tmol yr−2)since the mid-1980s,accompanied by a strong decadal variability dominated by oceanic climate modes.We subsequently revise the O_(2)-based carbon uptakes in response to this changing air-sea O_(2)flux.Our results show that,for the 1990−2000 period,the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively,overall consistent with estimates derived by the Global Carbon Project(GCP).An enhanced carbon uptake is found in both land and ocean after year 2000,reflecting the modification of carbon cycle under human activities.Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.展开更多
The Langmuir Probe(LAP), onboard the China Seismo-Electromagnetic Satellite(CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measu...The Langmuir Probe(LAP), onboard the China Seismo-Electromagnetic Satellite(CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measurement technology in the field of space exploration. The two main parameters measured by LAP are electron density and temperature. In this paper, a brief description of the LAP and its work mode are provided. Based on characteristics of the LAP, and assuming an ideal plasma environment, we introduce in detail a method used to invert the I-V curve; the data products that can be accessed by users are shown. Based on the LAP data available, this paper reports that events such as earthquakes and magnetic storms are preceded and followed by obvious abnormal changes. We suggest that LAP could provide a valuable data set for studies of space weather, seismic events, and the ionospheric environment.展开更多
Four levels of the data from the search coil magnetometer(SCM) onboard the China Seismo-Electromagnetic Satellite(CSES)are defined and described. The data in different levels all contain three components of the wavefo...Four levels of the data from the search coil magnetometer(SCM) onboard the China Seismo-Electromagnetic Satellite(CSES)are defined and described. The data in different levels all contain three components of the waveform and/or spectrum of the induced magnetic field around the orbit in the frequency range of 10 Hz to 20 kHz; these are divided into an ultra-low-frequency band(ULF,10–200 Hz), an extremely low frequency band(ELF, 200–2200 Hz), and a very low frequency band(VLF, 1.8–20 kHz). Examples of data products for Level-2, Level-3, and Level-4 are presented. The initial results obtained in the commission test phase demonstrated that the SCM was in a normal operational status and that the data are of high enough quality to reliably capture most space weather events related to low-frequency geomagnetic disturbances.展开更多
Doubly charged positive ions(dications)are an important component of planetary ionospheres because of the large energy required for their formation.Observations of these ions are exceptionally difficult due to their l...Doubly charged positive ions(dications)are an important component of planetary ionospheres because of the large energy required for their formation.Observations of these ions are exceptionally difficult due to their low abundances;until now,only atomic dications have been detected.The Neutral Gas and Ion Mass Spectrometer(NGIMS)measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications,CO2^++in this case,in a planetary upper atmosphere.The NGIMS data reveal a dayside averaged CO2^++distribution declining steadily from 5.6 cm^−3 at 160 km to below 1 cm^−3 above 200 km.The dominant CO2^++production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2^+at higher altitudes;CO2++destruction is dominated by natural dissociation,but reactions with atmospheric CO2 and O become important below 160 km.Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4.Finally,we report a much stronger solar control of the CO2^++density than of the CO2+density.展开更多
Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parame...Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well.The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence.MS magnitude has the strongest correlation with the co-seismic water level changes comparing to MW and ML magnitudes.There exists strong correlation between the maximum amplitude, step size and the oscillation duration.The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves.Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves.The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.展开更多
文摘Drought is a recurring dry condition with below-normal precipitation and is often associated with warm temperatures or heatwaves. A drought event can develop slowly over several weeks or suddenly within days, commonly under abnormal atmospheric conditions(e.g., quasi-stationary high-pressure systems), and can persist for weeks, months, or even years.
基金This work was jointly supported by a project supported by the Joint Fund of the National Natural Science Foundation of China and the China Meteorological Administration(Grant No.U2242209)the National Natural Science Foundation of China(Grant No.42175106).
文摘Dust storms are one of the most frequent meteorological disasters in China,endangering agricultural production,transportation,air quality,and the safety of people’s lives and property.Against the backdrop of climate change,Mongolia’s contribution to China’s dust cannot be ignored in recent years.In this study,we used the Weather Research and Forecasting model coupled with Chemistry(WRF-Chem),along with dynamic dust sources and the HYSPLIT model,to analyze the contributions of different dust sources to dust concentrations in northern China in March and April 2023.The results show that the frequency of dust storms in 2023 was the highest observed in the past decade.Mongolia and the Taklimakan Desert were identified as two main dust sources contributing to northern China.Specifically,Mongolia contributed more than 42%of dust,while the Taklimakan Desert accounted for 26%.A cold high-pressure center,a cold front,and a Mongolian cyclone resulted in the transport of dust aerosols from Mongolia and the Taklimakan Desert to northern China,where they affected most parts of the region.Moreover,two machine learning methods[the XGBoost algorithm and the Synthetic Minority Oversampling Technique(SMOTE)]were used to forecast the dust storms in March 2023,based on ground observations and WRF-Chem simulations over East Asia.XGBoost-SMOTE performed well in predicting hourly PM10 concentrations in China in March 2023,with a mean absolute error of 33.8μg m−3 and RMSE of 54.2μg m−3.
基金This work was supported by the Major Science and Technology Projects in Inner Mongolia Autonomous Region(No.2019ZD005)the National Natural Science Foundation of China(No.81903751)+1 种基金by the Natural Science Basic Research Project of Shaanxi Science and Technology Department(No.2019JQ-877)by the Scientific Research Project of Shaanxi Administration of Traditional Chinese Medicine(No.2019-ZZ-ZY018).
文摘Although Platycodon grandiflorum(Jacq.)A.DC.is a renowned medicine food homology plant,reports of excessive cadmium(Cd)levels are common,which affects its safety for clinical use and food consumption.To enable its Cd levels to be regulated or reduced,it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant,in addition to its detoxification mechanisms.This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P.grandiflorum.The experimental results showed that Cd was mainly accumulated in the roots[predominantly in the cell wall(50.96%-61.42%)],and it was found primarily in hypomobile and hypotoxic forms.The proportion of Cd in the soluble fraction increased after Cd exposure,and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves,with a higher increase in oxalate Cd.Therefore,it is likely that root retention mechanisms,cell wall deposition,vacuole sequestration,and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P.grandiflorum.The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P.grandiflorum,and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.
基金supported by the National Science Foundation of China(Grant Nos.41521004,41722502 and91637312)the China University Research Talents Recruitment Program(111 project,B13045)
文摘This article reviews recent progress in semi-arid climate change research in China.Results indicate that the areas of semiarid regions have increased rapidly during recent years in China,with an increase of 33%during 1994-2008 compared to 1948-62.Studies have found that the expansion rate of semi-arid areas over China is nearly 10 times higher than that of arid and sub-humid areas,and is mainly transformed from sub-humid/humid regions.Meanwhile,the greatest warming during the past 100 years has been observed over semi-arid regions in China,and mainly induced by radiatively forced processes.The intensity of the regional temperature response over semi-arid regions has been amplified by land-atmosphere interactions and human activities.The decadal climate variation in semi-arid regions is modulated by oceanic oscillations,which induce land-sea and north-south thermal contrasts and affect the intensities of westerlies,planetary waves and blocking frequencies.In addition,the drier climates in semi-arid regions across China are also associated with the weakened East Asian summer monsoon in recent years.Moreover,dust aerosols in semi-arid regions may have altered precipitation by affecting the local energy and hydrological cycles.Finally,semi-arid regions in China are projected to continuously expand in the 21st century,which will increase the risk of desertification in the near future.
文摘The virus SARS-CoV2,which causes the Coronavirus disease COVID-19 has become a pandemic and has spread to every inhabited continent.Given the increasing caseload,there is an urgent need to augment clinical skills in order to identify from among the many mild cases the few that will progress to critical illness.We present a first step towards building an artificial intelligence(AI)framework,with predictive analytics(PA)capabilities applied to real patient data,to provide rapid clinical decision-making support.COVID-19 has presented a pressing need as a)clinicians are still developing clinical acumen given the disease’s novelty,and b)resource limitations in a rapidly expanding pandemic require difficult decisions relating to resource allocation.The objectives of this research are:(1)to algorithmically identify the combinations of clinical characteristics of COVID-19 that predict outcomes,and(2)to develop a tool with AI capabilities that will predict patients at risk for more severe illness on initial presentation.The predictive models learn from historical data to help predict specifically who will develop acute respiratory distress syndrome(ARDS),a severe outcome in COVID-19.Our experimental results based on two hospitals in Wenzhou,Zhejang,China identify features most predictive of ARDS in COVID-19 initial presentation which would not have stood out to clinicians.A mild increase in elevated alanine aminotransferase(ALT)(a liver enzyme)),a presence of myalgias(body aches),and an increase in hemoglobin,in this order,are the clinical features,on presentation,that are the most predictive.Those two centers’COVID-19 case series symptoms on initial presentation can help predict severe outcomes.Predictive models that learned from historical data of patients from two Chinese hospitals achieved 70%to 80%accuracy in predicting severe cases.
基金supported by the National Natural Science Foundation of China (GrantNo. 40725015)
文摘Three approaches,i.e.,the harmonic analysis(HA) technique,the thermal diffusion equation and correction(TDEC) method,and the calorimetric method used to estimate ground heat flux,are evaluated by using observations from the Semi-Arid Climate and Environment Observatory of Lanzhou University(SACOL) in July,2008.The calorimetric method,which involves soil heat flux measurement with an HFP01SC self-calibrating heat flux plate buried at a depth of 5 cm and heat storage in the soil between the plate and the surface,is here called the ITHP approach.The results show good linear relationships between the soil heat fluxes measured with the HFP01SC heat flux plate and those calculated with the HA technique and the TDEC method,respectively,at a depth of 5 cm.The soil heat fluxes calculated with the latter two methods well follow the phase measured with the HFP01SC heat flux plate.The magnitudes of the soil heat flux calculated with the HA technique and the TDEC method are close to each other,and they are about 2 percent and 6 percent larger than the measured soil heat flux,respectively,which mainly occur during the nighttime.Moreover,the ground heat fluxes calculated with the TDEC method and the HA technique are highly correlated with each other(R2 = 0.97),and their difference is only about 1 percent.The TDEC-calculated ground heat flux also has a good linear relationship with the ITHP-calculated ground heat flux(R2 = 0.99),but their difference is larger(about 9 percent).Furthermore,compared to the HFP01SC direct measurements at a depth of 5 cm,the ground heat flux calculated with the HA technique,the TDEC method,and the ITHP approach can improve the surface energy budget closure by about 6 percent,7 percent,and 6 percent at SACOL site,respectively.Therefore,the contribution of ground heat flux to the surface energy budget is very important for the semi-arid grassland over the Loess Plateau in China.Using turbulent heat fluxes with common corrections,soil heat storage be-tween the surface and the heat flux plate can improve the surface energy budget closure by about 6 to 7 percent,resulting in a clo-sure of 82 to 83 percent at the SACOL site.
基金This work was jointly supported by the National Natural Science Foundation of China[grant numbers 41521004 and 41875083]the Gansu Provincial Special Fund Project for Guiding Scientific and Technological Innovation and Development[grant number 2019ZX-06].
基金supported by the civil space research project (ZH-1 data validation: Ionospheric observatory theory)NFSC grants 41574139 and 41874174
文摘Previous studies have reported that, before or after occurrences of strong earthquakes, some low earth orbit satellites recorded ionospheric disturbances, including electromagnetic emissions and plasma fluctuations over the epicenter region or its conjugate point.Theoretically speaking, due to some electromagnetic coupling effect, electromagnetic emissions from the earthquake preparation zone could propagate from the lithosphere to the atmosphere, and could reach the ionosphere, even up to the inner magnetosphere. This paper introduces the electric field detector(EFD) onboard the ZhangHeng-1 satellite(ZH-1). The EFD is designed to measure electric field fluctuations within the broad frequency range of DC to 3.5 MHz, divided into 4 channels: ULF(DC–16 Hz), ELF(6 Hz–2.2 kHz), VLF(1.8 kHz–20 kHz) and HF(18 kHz–3.5 MHz). The sampling rates of the channels are 125 Hz, 5 kHz, 50 kHz and 10 MHz, respectively. The EFD includes4 spherical probes mounted on a over 4.5 m boom and an electronic box inside the satellite module. The resolution of the EFD is 1μV·m-1·Hz-1/2 at frequencies from DC to 16 Hz, and the sensitivity is 0.1 μV·m-1·Hz-1/2 at frequencies from 6 Hz to 2.2 kHz, 0.05 μV·m-1·Hz-1/2 in the band 1.8 kHz to 20 kHz, and 0.1μV·m-1·Hz-1/2 from 20 kHz to 3.5 MHz. The dynamic range from DC to 20 kHz is over 120 dB, and over96 dB from 20 kHz to 3.5 MHz. The EFD has two observation modes: survey mode and burst mode. The survey mode concentrates primarily on electric field power density values; the burst mode provides high sampling rate waveform data. The detailed configuration of the EFD onboard the ZH-1 is also introduced in this paper. During the six months' orbit test phase, the EFD recorded a number of natural electromagnetic emissions. Preliminary analysis of these data suggests that the EFD performs well onboard the ZH-1 and is meeting the requirements of the scientific objectives of ZH-1.
基金supported by the National Science Foundation of China (Grant Nos. 41521004, 41575006 and 41705047)the China 111 project (Grant No. B13045)the Foundation of the Key Laboratory for Semi-Arid Climate Change of the Ministry of Education in Lanzhou University from the Fundamental Research Funds for the Central Universities (Grant No. lzujbky-2017-bt04)
文摘Although atmospheric greenhouse gas concentrations continuously increased, there was relatively little change in global-averaged surface temperatures from 1998 to 2013, which is known as atmospheric warming slowdown. For further understanding the mechanism involved, we explored the energy redistribution between the atmosphere and ocean in different latitudes and depths by using data analysis as well as simulations of a coupled atmosphere–ocean box model. The results revealed that, compared with observational changes of ocean heat content (OHC) associated with rapid warming, the OHC changes related to warming slowdown are relatively larger in multiple ocean basins, particularly in the deeper layer of the Atlantic. The coupled box model also showed that there is a larger increasing trend of OHC under the warming slowdown scenario than the rapid warming scenario. Particularly, during the warming slowdown period, the heat storage in the deeper ocean increases faster than the ocean heat uptake in the surface ocean. The simulations indicated that the warming patterns under the two scenarios are accompanied by distinct outgoing longwave radiation and atmospheric meridional heat transport, as well as other related processes, thus leading to different characteristics of ocean heat uptake. Due to the global energy balance, we suggest this slowdown has a tight relationship with the accelerated heat transport into the global ocean.
基金supported by the National Natural Science Foundation of China (41404058)
文摘The CSES(China seismic electromagnetic satellite) was launched on February 2, 2018 in a circular polar orbit at an altitude of～507 km. One of the main objectives of CSES is to search for and characterize ionospheric perturbations that can be associated with seismic activities, to better understand the generation mechanism of such perturbations. Its scientific payload can measure a broad frequency range of electromagnetic waves and some important plasma parameters. This paper is a first-hand study of unusual observations recorded by the CSES over seismic regions prior to four earthquakes with M >7.0 since the satellite's launch. CSES detectors measured irregularities near the epicenter of these four earthquakes. It is already clear that data from instruments onboard the CSES will be of significant help in studies of characteristics of ionospheric perturbations related to earthquakes and their generation mechanisms.
基金supported by the National Science Foundation of China(Grant.No.41521004)the Gansu Provincial Special Fund Project for Guiding Scientific and Technological Innovation and Development(Grant No.2019ZX-06)the Fundamental Research Funds for the Central Universit-ies(lzujbky-2021-kb12)。
文摘Estimating the impacts on PM_(2.5)pollution and CO_(2)emissions by human activities in different urban regions is important for developing efficient policies.In early 2020,China implemented a lockdown policy to contain the spread of COVID-19,resulting in a significant reduction of human activities.This event presents a convenient opportunity to study the impact of human activities in the transportation and industrial sectors on air pollution.Here,we investigate the variations in air quality attributed to the COVID-19 lockdown policy in the megacities of China by combining in-situ environmental and meteorological datasets,the Suomi-NPP/VIIRS and the CO_(2)emissions from the Carbon Monitor project.Our study shows that PM_(2.5)concentrations in the spring of 2020 decreased by 41.87%in the Yangtze River Delta(YRD)and 43.30%in the Pearl River Delta(PRD),respectively,owing to the significant shutdown of traffic and manufacturing industries.However,PM_(2.5)concentrations in the Beijing-Tianjin-Hebei(BTH)region only decreased by 2.01%because the energy and steel industries were not fully paused.In addition,unfavorable weather conditions contributed to further increases in the PM_(2.5)concentration.Furthermore,CO_(2)concentrations were not significantly affected in China during the short-term emission reduction,despite a 19.52%reduction in CO_(2)emissions compared to the same period in 2019.Our results suggest that concerted efforts from different emission sectors and effective long-term emission reduction strategies are necessary to control air pollution and CO_(2)emissions.
基金supported by the Civil Space Research project (ZH1 data validation: Ionospheric observatory theory)NFSC grant 41574139 and 41874174
文摘The China Seismo-Electromagnetic Satellite, launched into orbit from Jiuquan Satellite Launch Centre on February 2 nd, 2018, is China's first space satellite dedicated to geophysical exporation. The satellite carries eight scientific payloads including high-precision magnetometers to detect electromagnetic changes in space, in particular changes associated with global earthquake disasters. In order to encourage and facilitate use by geophysical scientists of data from the satellite's payloads, this paper introduces the application systems developed for the China Seismo-Electromagnetic Satellite by the Institute of Crustal Dynamics, China Earthquake Administration;these include platform construction, data classification, data storage, data format, and data access and acquisition.
基金supported by a research grant from the Institute of Crustal Dynamics, China Earthquake Administration (No. ZDJ2017-20)
文摘The high energetic particle package(HEPP) on-board the China Seismo-Electromagnetic Satellite(CSES) was launched on February 2, 2018. This package includes three independent detectors: HEPP-H, HEPP-L, and HEPP-X. HEPP-H and HEPP-L can detect energetic electrons from 100 keV to approximately 50 MeV and protons from 2 MeV to approximately 200 MeV. HEPP-X can measure solar X-rays in the energy range from 1 keV to approximately 20 keV. The objective of the HEPP payload was to provide a survey of energetic particles with high energy, pitch angle, and time resolutions in order to gain new insight into the space radiation environments of the near-Earth system. Particularly, the HEPP can provide new measurements of the magnetic storm related precipitation of electrons in the slot region, and the dynamics of radiation belts. In this paper, the HEPP scientific data sets are described and initial results are provided.The scientific data can show variations in the flux of energetic particles during magnetic storms.
基金the World Climate Recruitment Programme’s (WCRP) Working Group on Coupled Modelling (WGCM)the Global Organization for Earth System Science Portals (GO-ESSP)+2 种基金jointly supported by the National Science Foundation of China (Grant Nos. 41991231, 91937302)the China 111 project (Grant No. B13045)supported by Supercomputing Center of Lanzhou University
文摘The measurement of atmospheric O_(2)concentrations and related oxygen budget have been used to estimate terrestrial and oceanic carbon uptake.However,a discrepancy remains in assessments of O_(2)exchange between ocean and atmosphere(i.e.air-sea O_(2)flux),which is one of the major contributors to uncertainties in the O_(2)-based estimations of the carbon uptake.Here,we explore the variability of air-sea O_(2)flux with the use of outputs from Coupled Model Intercomparison Project phase 6(CMIP6).The simulated air-sea O_(2)flux exhibits an obvious warming-induced upward trend(~1.49 Tmol yr−2)since the mid-1980s,accompanied by a strong decadal variability dominated by oceanic climate modes.We subsequently revise the O_(2)-based carbon uptakes in response to this changing air-sea O_(2)flux.Our results show that,for the 1990−2000 period,the averaged net ocean and land sinks are 2.10±0.43 and 1.14±0.52 GtC yr−1 respectively,overall consistent with estimates derived by the Global Carbon Project(GCP).An enhanced carbon uptake is found in both land and ocean after year 2000,reflecting the modification of carbon cycle under human activities.Results derived from CMIP5 simulations also investigated in the study allow for comparisons from which we can see the vital importance of oxygen dataset on carbon uptake estimations.
基金supported by the National Natural Science Foundation of China (41404058)Beijing Natural Science Foundation (8184091)
文摘The Langmuir Probe(LAP), onboard the China Seismo-Electromagnetic Satellite(CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measurement technology in the field of space exploration. The two main parameters measured by LAP are electron density and temperature. In this paper, a brief description of the LAP and its work mode are provided. Based on characteristics of the LAP, and assuming an ideal plasma environment, we introduce in detail a method used to invert the I-V curve; the data products that can be accessed by users are shown. Based on the LAP data available, this paper reports that events such as earthquakes and magnetic storms are preceded and followed by obvious abnormal changes. We suggest that LAP could provide a valuable data set for studies of space weather, seismic events, and the ionospheric environment.
基金supported by the State Key R&D Project (Grant No. 2016YFE0122200)the Civil Aerospace Scientific Research Project “Data calibration and validation for CSES, ”the Central-Level Public Welfare Research Projects of the Institute of Crustal Dynamics Institute, China Earthquake Administration (Grant No. ZDJ2017-21)
文摘Four levels of the data from the search coil magnetometer(SCM) onboard the China Seismo-Electromagnetic Satellite(CSES)are defined and described. The data in different levels all contain three components of the waveform and/or spectrum of the induced magnetic field around the orbit in the frequency range of 10 Hz to 20 kHz; these are divided into an ultra-low-frequency band(ULF,10–200 Hz), an extremely low frequency band(ELF, 200–2200 Hz), and a very low frequency band(VLF, 1.8–20 kHz). Examples of data products for Level-2, Level-3, and Level-4 are presented. The initial results obtained in the commission test phase demonstrated that the SCM was in a normal operational status and that the data are of high enough quality to reliably capture most space weather events related to low-frequency geomagnetic disturbances.
基金supported by the B-type Strategic Priority Program No.XDB41000000funded by the Chinese Academy of Sciences,and the pre-research projects on Civil Aerospace Technologies No.D020105 and D020103+1 种基金funded by China's National Space Administrationthe National Science Foundation of China through grants 41525015 and 41774186 to JC,41904154 to WXS,and 41525016 to YW.
文摘Doubly charged positive ions(dications)are an important component of planetary ionospheres because of the large energy required for their formation.Observations of these ions are exceptionally difficult due to their low abundances;until now,only atomic dications have been detected.The Neutral Gas and Ion Mass Spectrometer(NGIMS)measurements made on board the recent Mars Atmosphere and Volatile Evolution mission provide the first opportunity for decisive detection of molecular dications,CO2^++in this case,in a planetary upper atmosphere.The NGIMS data reveal a dayside averaged CO2^++distribution declining steadily from 5.6 cm^−3 at 160 km to below 1 cm^−3 above 200 km.The dominant CO2^++production mechanisms are double photoionization of CO2 below 190 km and single photoionization of CO2^+at higher altitudes;CO2++destruction is dominated by natural dissociation,but reactions with atmospheric CO2 and O become important below 160 km.Simplified photochemical model calculations are carried out and reasonably reproduce the data at low altitudes within a factor of 2 but underestimate the data at high altitudes by a factor of 4.Finally,we report a much stronger solar control of the CO2^++density than of the CO2+density.
基金supported by National Natural Science Foundation of China (No. 40574020)Basic Research item of Institute of Earthquake Science, China Earthquake Administration (No. 0207690236).
文摘Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well.The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence.MS magnitude has the strongest correlation with the co-seismic water level changes comparing to MW and ML magnitudes.There exists strong correlation between the maximum amplitude, step size and the oscillation duration.The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves.Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves.The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.
