本文研究了2000年10月5日磁暴主相两个不同时段期间环电流的变化速度与相应太阳风参数的关系.研究发现,磁暴主相期间环电流的变化速度并不取决于行星际磁场南向分量的平均值和最大值,也不取决于太阳风电场的平均值和最大值.本文的研究证...本文研究了2000年10月5日磁暴主相两个不同时段期间环电流的变化速度与相应太阳风参数的关系.研究发现,磁暴主相期间环电流的变化速度并不取决于行星际磁场南向分量的平均值和最大值,也不取决于太阳风电场的平均值和最大值.本文的研究证明,磁暴环电流增强期间环电流的变化速度,不仅取决于行星际磁场南向分量和太阳风的速度,还取决于太阳风的动压,而且太阳风的动压起着非常重要的作用.研究还发现,采用Burton et al.(1975)方程和O′Brien,McPherron (2000a)方程估算得到的2000年10月5日的两次地磁活动的强度远低于实际的观测值.展开更多
The Global Precipitation Measurement(GPM)dual-frequency precipitation radar(DPR)products(Version 07A)are employed for a rigorous comparative analysis with ground-based operational weather radar(GR)networks.The reflect...The Global Precipitation Measurement(GPM)dual-frequency precipitation radar(DPR)products(Version 07A)are employed for a rigorous comparative analysis with ground-based operational weather radar(GR)networks.The reflectivity observed by GPM Ku PR is compared quantitatively against GR networks from CINRAD of China and NEXRAD of the United States,and the volume matching method is used for spatial matching.Additionally,a novel frequency correction method for all phases as well as precipitation types is used to correct the GPM Ku PR radar frequency to the GR frequency.A total of 20 GRs(including 10 from CINRAD and 10 from NEXRAD)are included in this comparative analysis.The results indicate that,compared with CINRAD matched data,NEXRAD exhibits larger biases in reflectivity when compared with the frequency-corrected Ku PR.The root-mean-square difference for CINRAD is calculated at 2.38 d B,whereas for NEXRAD it is 3.23 d B.The mean bias of CINRAD matched data is-0.16 d B,while the mean bias of NEXRAD is-2.10 d B.The mean standard deviation of bias for CINRAD is 2.15 d B,while for NEXRAD it is 2.29 d B.This study effectively assesses weather radar data in both the United States and China,which is crucial for improving the overall consistency of global precipitation estimates.展开更多
One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific object...One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.展开更多
Early detection of convective clouds is vital for minimizing hazardous impacts.Forecasting convective initiation(CI)using current multispectral geostationary meteorological satellites is often challenged by high false...Early detection of convective clouds is vital for minimizing hazardous impacts.Forecasting convective initiation(CI)using current multispectral geostationary meteorological satellites is often challenged by high false-alarm rates and missed detections caused by limited resolution.In contrast,high-resolution earth observation satellites offer more detailed texture information,improving early detection capabilities.The authors propose a novel methodology that integrates the advanced features of China’s latest-generation satellites,Gaofen-4(GF-4)and Fengyun-4A(FY-4A).This fusion method retains GF’s high-resolution details and FY-4A’s multispectral information.Two cases from different observational scenarios and weather conditions under GF-4’s staring mode were carried out to compare the CI forecast results based on fused data and solely on FY-4A data.The fused data demonstrated superior performance in detecting smaller-scale convective clouds,enabling earlier forecasting with a lead time of 15–30 minutes,and more accurate location identification.Integrating high-resolution earth observation satellites into early convective cloud detection provides valuable insights for forecasters and decision-makers,particularly given the current resolution limitations of geostationary meteorological satellites.展开更多
Partitioning the solar cycle into ascending and descending phases,we examine the solar cycle distribution of the north-south(N-S)asymmetry in the source locations of super geomagnetic storms(SGSs;Dst≤-250 nT)during 1...Partitioning the solar cycle into ascending and descending phases,we examine the solar cycle distribution of the north-south(N-S)asymmetry in the source locations of super geomagnetic storms(SGSs;Dst≤-250 nT)during 1932-2018.We found that during the ascending phases,SGS source locations were predominantly in the northern hemisphere(NH),exhibiting significant N-S asymmetry.For the SGSs in the descending phases,source locations of the SGSs dominated in the NH and N-S asymmetry was only significant in the western hemisphere.For the period from 1932 to 2018,the source locations of SGSs were predominantly in the NH,and the N-S asymmetry was significant.The cumulative numbers of SGSs originating from the two hemispheres were strongly anticorrelated during the ascending phases,descending phases,and the entire period from 1932 to 2018.For the source locations of SGSs with different intensities,significant N-S asymmetries were observed in the source location distribution.Specifically,for all SGSs,SGSs with-400 nT<Dst≤-300 nT,and SGSs with Dst≤-300 nT,the NH exhibited a higher number of events compared to the southern hemisphere(SH),indicating a dominance of SGSs in the NH.From the perspective of the evolution of N-S asymmetry with the solar cycle,the source locations of the SGSs always dominated in the NH during the ascending phases.However,during solar cycles 17-19 and 21,the source locations of the SGSs dominated in the NH,while during solar cycles 20,22,and 23 the source locations of the SGSs dominated in the SH.From the perspective of N-S asymmetry for Solar Cycles 17-23,solar activity across the two hemispheres is largely balanced.However,the solar activities manifested by CMEs that can trigger SGSs during Solar Cycles 17-23 were predominantly in the NH.Therefore,factors beyond solar activity,such as the propagation of the CMEs from the Sun to the Earth,likely contribute to the observed N-S asymmetric distribution of the source locations of SGSs.展开更多
We examined the heliolatitude distribution and North-South(N-S)asymmetry of Ground Level Enhancement(GLE)event source locations from 1942 to 2024,finding distinct patterns between the periods 1942–1979 and1980–2024....We examined the heliolatitude distribution and North-South(N-S)asymmetry of Ground Level Enhancement(GLE)event source locations from 1942 to 2024,finding distinct patterns between the periods 1942–1979 and1980–2024.Between 1942 and 1979,33 GLE events were recorded:5 from the southern hemisphere within[S3,S11]and 28 from the northern hemisphere within[N7,N37].The southeast quadrant was devoid of any source locations for GLE events.45.4%of the source locations of the GLE events were within the latitudinal range of[S15,N15].The remaining source locations of the GLE events were distributed at latitudes above 15°in the northern hemisphere.Between 1980 and 2024,43 GLE events were recorded:25 from the southern hemisphere and 18 from the northern hemisphere,with all events above 30°latitude originating from the northern hemisphere.Approximately 44.2%of the source locations of the GLE events were distributed within the latitudinal band[S15,N15].Over the period from 1942 to 2024,44.7%within[S15,N15],63.2%within[S20,N20],80.3%within[S25,N25],88.2%within[S30,N30],and 11.8%at latitudes above 30°.N-S asymmetry was significant at latitudes above 0°,5°,10°,15°,20°and 30°,with northern hemisphere dominance.Moreover,a strong inverse correlation exists between the number of GLE events from the northern and southern hemispheres at latitudes above 0°,5°,10°,15°,20°,25°and 30°.展开更多
文摘本文研究了2000年10月5日磁暴主相两个不同时段期间环电流的变化速度与相应太阳风参数的关系.研究发现,磁暴主相期间环电流的变化速度并不取决于行星际磁场南向分量的平均值和最大值,也不取决于太阳风电场的平均值和最大值.本文的研究证明,磁暴环电流增强期间环电流的变化速度,不仅取决于行星际磁场南向分量和太阳风的速度,还取决于太阳风的动压,而且太阳风的动压起着非常重要的作用.研究还发现,采用Burton et al.(1975)方程和O′Brien,McPherron (2000a)方程估算得到的2000年10月5日的两次地磁活动的强度远低于实际的观测值.
基金funded by the National Key Research and Development Program of China(Grant No.2023YFB3907500)the National Natural Science Foundation(Grant No.42330602)the“Fengyun Satellite Remote Sensing Product Validation and Verification”Youth Innovation Team of the China Meteorological Administration(Grant No.CMA2023QN12)。
文摘The Global Precipitation Measurement(GPM)dual-frequency precipitation radar(DPR)products(Version 07A)are employed for a rigorous comparative analysis with ground-based operational weather radar(GR)networks.The reflectivity observed by GPM Ku PR is compared quantitatively against GR networks from CINRAD of China and NEXRAD of the United States,and the volume matching method is used for spatial matching.Additionally,a novel frequency correction method for all phases as well as precipitation types is used to correct the GPM Ku PR radar frequency to the GR frequency.A total of 20 GRs(including 10 from CINRAD and 10 from NEXRAD)are included in this comparative analysis.The results indicate that,compared with CINRAD matched data,NEXRAD exhibits larger biases in reflectivity when compared with the frequency-corrected Ku PR.The root-mean-square difference for CINRAD is calculated at 2.38 d B,whereas for NEXRAD it is 3.23 d B.The mean bias of CINRAD matched data is-0.16 d B,while the mean bias of NEXRAD is-2.10 d B.The mean standard deviation of bias for CINRAD is 2.15 d B,while for NEXRAD it is 2.29 d B.This study effectively assesses weather radar data in both the United States and China,which is crucial for improving the overall consistency of global precipitation estimates.
基金Supported by the National Natural Science Foundation of China(42474239,41204128)China National Space Administration(Pre-research project on Civil Aerospace Technologies No.D010301)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA17010303)。
文摘One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.
基金supported by the Demonstration System for High Resolution Meteorological Application(Ⅱ)[grant number 32-Y30F08-9001-20/22]the National Natural Science Foundation of China[grant numbers 12292981 and 12292984]。
文摘Early detection of convective clouds is vital for minimizing hazardous impacts.Forecasting convective initiation(CI)using current multispectral geostationary meteorological satellites is often challenged by high false-alarm rates and missed detections caused by limited resolution.In contrast,high-resolution earth observation satellites offer more detailed texture information,improving early detection capabilities.The authors propose a novel methodology that integrates the advanced features of China’s latest-generation satellites,Gaofen-4(GF-4)and Fengyun-4A(FY-4A).This fusion method retains GF’s high-resolution details and FY-4A’s multispectral information.Two cases from different observational scenarios and weather conditions under GF-4’s staring mode were carried out to compare the CI forecast results based on fused data and solely on FY-4A data.The fused data demonstrated superior performance in detecting smaller-scale convective clouds,enabling earlier forecasting with a lead time of 15–30 minutes,and more accurate location identification.Integrating high-resolution earth observation satellites into early convective cloud detection provides valuable insights for forecasters and decision-makers,particularly given the current resolution limitations of geostationary meteorological satellites.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.41774085,41074132,41274193 and 41674166)the Special Fund of the Institute of Geophysics,China Earthquake Administration(grant Nos.DQJB22X12 and DQJB24X25)。
文摘Partitioning the solar cycle into ascending and descending phases,we examine the solar cycle distribution of the north-south(N-S)asymmetry in the source locations of super geomagnetic storms(SGSs;Dst≤-250 nT)during 1932-2018.We found that during the ascending phases,SGS source locations were predominantly in the northern hemisphere(NH),exhibiting significant N-S asymmetry.For the SGSs in the descending phases,source locations of the SGSs dominated in the NH and N-S asymmetry was only significant in the western hemisphere.For the period from 1932 to 2018,the source locations of SGSs were predominantly in the NH,and the N-S asymmetry was significant.The cumulative numbers of SGSs originating from the two hemispheres were strongly anticorrelated during the ascending phases,descending phases,and the entire period from 1932 to 2018.For the source locations of SGSs with different intensities,significant N-S asymmetries were observed in the source location distribution.Specifically,for all SGSs,SGSs with-400 nT<Dst≤-300 nT,and SGSs with Dst≤-300 nT,the NH exhibited a higher number of events compared to the southern hemisphere(SH),indicating a dominance of SGSs in the NH.From the perspective of the evolution of N-S asymmetry with the solar cycle,the source locations of the SGSs always dominated in the NH during the ascending phases.However,during solar cycles 17-19 and 21,the source locations of the SGSs dominated in the NH,while during solar cycles 20,22,and 23 the source locations of the SGSs dominated in the SH.From the perspective of N-S asymmetry for Solar Cycles 17-23,solar activity across the two hemispheres is largely balanced.However,the solar activities manifested by CMEs that can trigger SGSs during Solar Cycles 17-23 were predominantly in the NH.Therefore,factors beyond solar activity,such as the propagation of the CMEs from the Sun to the Earth,likely contribute to the observed N-S asymmetric distribution of the source locations of SGSs.
基金supported by the National Natural Science Foundation of China(grant Nos.42374092,41074132,41274193,41474166,41774195,and 41874187)the Special Fund of the Institute of Geophysics,China Earthquake Administration(Grant Number DQJB22X12)。
文摘We examined the heliolatitude distribution and North-South(N-S)asymmetry of Ground Level Enhancement(GLE)event source locations from 1942 to 2024,finding distinct patterns between the periods 1942–1979 and1980–2024.Between 1942 and 1979,33 GLE events were recorded:5 from the southern hemisphere within[S3,S11]and 28 from the northern hemisphere within[N7,N37].The southeast quadrant was devoid of any source locations for GLE events.45.4%of the source locations of the GLE events were within the latitudinal range of[S15,N15].The remaining source locations of the GLE events were distributed at latitudes above 15°in the northern hemisphere.Between 1980 and 2024,43 GLE events were recorded:25 from the southern hemisphere and 18 from the northern hemisphere,with all events above 30°latitude originating from the northern hemisphere.Approximately 44.2%of the source locations of the GLE events were distributed within the latitudinal band[S15,N15].Over the period from 1942 to 2024,44.7%within[S15,N15],63.2%within[S20,N20],80.3%within[S25,N25],88.2%within[S30,N30],and 11.8%at latitudes above 30°.N-S asymmetry was significant at latitudes above 0°,5°,10°,15°,20°and 30°,with northern hemisphere dominance.Moreover,a strong inverse correlation exists between the number of GLE events from the northern and southern hemispheres at latitudes above 0°,5°,10°,15°,20°,25°and 30°.
