Extracting and parameterizing ionospheric waves globally and statistically is a longstanding problem. Based on the multichannel maximum entropy method（MMEM） used for studying ionospheric waves by previous work, we c...Extracting and parameterizing ionospheric waves globally and statistically is a longstanding problem. Based on the multichannel maximum entropy method（MMEM） used for studying ionospheric waves by previous work, we calculate the parameters of ionospheric waves by applying the MMEM to numerously temporally approximate and spatially close global-positioning-system radio occultation total electron content profile triples provided by the unique clustered satellites flight between years 2006 and 2007 right after the constellation observing system for meteorology, ionosphere, and climate（COSMIC） mission launch. The results show that the amplitude of ionospheric waves increases at the low and high latitudes（~0.15 TECU） and decreases in the mid-latitudes（~0.05 TECU）. The vertical wavelength of the ionospheric waves increases in the mid-latitudes（e.g., ~50 km at altitudes of 200–250 km） and decreases at the low and high latitudes（e.g., ~35 km at altitudes of 200–250 km）.The horizontal wavelength shows a similar result（e.g., ~1400 km in the mid-latitudes and ~800 km at the low and high latitudes）.展开更多
DArk Matter Particle Explorer(DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 Ge V to 10 Te V and hundreds of Te V ...DArk Matter Particle Explorer(DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 Ge V to 10 Te V and hundreds of Te V for nuclei. This paper provides a method using machine learning to identify electrons and separate them from gammas, protons, helium and heavy nuclei with the DAMPE data acquired from 2016 January 1 to 2017 June 30, in the energy range from 10 to 100 Ge V.展开更多
We use the latest baryon acoustic oscillation and Union 2.1 type Ia supernova data to test the cosmic opacity between different redshift regions without assuming any cosmological models. It is found that the universe ...We use the latest baryon acoustic oscillation and Union 2.1 type Ia supernova data to test the cosmic opacity between different redshift regions without assuming any cosmological models. It is found that the universe may be opaque between the redshift regions 0.35 0.44, 0.44 0.57 and 0.6-0.73 since the best fit values of cosmic opacity in these regions are positive, while a transparent universe is favored in the redshift region 0.57-0.63. However, in general, a transparent universe is still consistent with observations at the lo confidence level.展开更多
针对COSMIC(Constellation Observation System of Meteorology Ionosphere and Climate)掩星反演的大气温度和水汽压二级资料,利用常规探空观测和NCEP(National Centers for Environmental Prediction)分析资料分别进行质量检验分析,...针对COSMIC(Constellation Observation System of Meteorology Ionosphere and Climate)掩星反演的大气温度和水汽压二级资料,利用常规探空观测和NCEP(National Centers for Environmental Prediction)分析资料分别进行质量检验分析,以揭示反演资料质量的海陆差异、随纬度和高度变化等三维空间特征。结果显示:我国区域反演资料的温度略低于探空观测与NCEP分析资料,温度与水汽压相对于检验资料的均方根误差较小;全球范围内,反演大气温湿资料的质量随高度和纬度的不同而存在明显差异,而且海洋和陆地上质量的水平和垂直分布特征也存在显著不同。总体上看,COSMIC反演大气温湿资料具有良好的可靠性与精确度,可作为我国数值预报资料同化的新资料,反演温湿资料的质量特征也可为COSMIC资料同化的质量控制和垂直稀疏化方案的设计提供科学依据。展开更多
使用COSMIC数据分析和管理中心(COSMIC data analysis and archive center,CDAAC)提供的level 1b数据中的掩星事件表和观测路径上的绝对电子含量资料,在假设电离层各层电子密度相同的前提下,对Abel积分公式进行离散化,并使用最小二乘方...使用COSMIC数据分析和管理中心(COSMIC data analysis and archive center,CDAAC)提供的level 1b数据中的掩星事件表和观测路径上的绝对电子含量资料,在假设电离层各层电子密度相同的前提下,对Abel积分公式进行离散化,并使用最小二乘方法求解。其结果与COSMIC所提供的电离层廓线产品符合度较高,且二者的绝对误差的平均值和标准差分别为-1.52×103el/cm3和6.61×103el/cm3,相对误差的平均值和标准差分别为0.5%和2.9%。所使用的方法计算简便,并且精度与COSMIC产品一致。展开更多
为研究COSMIC(constellation observing system for meteorology,ionosphere and climate)掩星反演湿温廓线的质量,需对数据误差特性进行量化研究。首先采用线性插值的方法,以时间窗3 h、水平距离300 km为匹配准则,对0.2~30 km各高度层...为研究COSMIC(constellation observing system for meteorology,ionosphere and climate)掩星反演湿温廓线的质量,需对数据误差特性进行量化研究。首先采用线性插值的方法,以时间窗3 h、水平距离300 km为匹配准则,对0.2~30 km各高度层温度的平均偏差和标准差进行统计分析,研究随海拔高、季节和纬度带变化的温度平均偏差特性。然后采用2016年的全球探空数据集分析全球区域的COSMIC湿温廓线质量,以及北温带COSMIC湿温廓线质量随季节变化的特点,探究不同纬度带地区COSMIC掩星湿温廓线质量随纬度变化的特点。结果表明,全球范围内温度平均偏差为-0.16 K,掩星数据和探空站资料精度相当;季节变化的统计量F=0.999 6>0.05,该因素对COSMIC湿温廓线质量影响不显著;纬度带变化的统计量F=0.024 4<0.05,该因素对COSMIC湿温廓线质量有显著影响,尤其是热带地区受水汽影响较大,温度平均偏差处于峰值,偏差高于0.25 K,南温带地区次之。展开更多
电离层foF2是短波通信、天波超视距雷达系统所需的关键环境参数,使用2006—2014年COMSIC(constellation observing system for meteorology,ionosphere,and climate)掩星电离层数据和多项式方法,自主构建了高精度全球电离层foF2经验模型...电离层foF2是短波通信、天波超视距雷达系统所需的关键环境参数,使用2006—2014年COMSIC(constellation observing system for meteorology,ionosphere,and climate)掩星电离层数据和多项式方法,自主构建了高精度全球电离层foF2经验模型,并使用2015—2019年观测数据进行独立检验。本模型结果与建模及独立检验时段电离层foF2观测数据的相关系数分别为0.948和0.937,平均偏差分别为2.38%和3.08%,相对误差分别为11.72%和12.69%。利用该模型研究了电离层foF2时空变化特征,结果表明电离层foF2日夜变化幅度随纬度增加而变大,春秋分季期间南半球日夜变化幅度显著高于北半球,而夏季半球则远低于冬季半球。电离层foF2季节变化幅度随纬度增加而变大,夜间电离层foF2的季节变化以年特征为主,白天则包含了显著的年、半年特征,夜间季节变化幅度明显高于白天,南半球显著高于北半球。电离层foF2中纬槽现象主要出现在春秋分季夜间,经度方向四波结构主要出现在太阳活动低年和春秋分季期间。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 41774158,41474129 and 41704148the Chinese Meridian Projectthe Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No2011324
文摘Extracting and parameterizing ionospheric waves globally and statistically is a longstanding problem. Based on the multichannel maximum entropy method（MMEM） used for studying ionospheric waves by previous work, we calculate the parameters of ionospheric waves by applying the MMEM to numerously temporally approximate and spatially close global-positioning-system radio occultation total electron content profile triples provided by the unique clustered satellites flight between years 2006 and 2007 right after the constellation observing system for meteorology, ionosphere, and climate（COSMIC） mission launch. The results show that the amplitude of ionospheric waves increases at the low and high latitudes（~0.15 TECU） and decreases in the mid-latitudes（~0.05 TECU）. The vertical wavelength of the ionospheric waves increases in the mid-latitudes（e.g., ~50 km at altitudes of 200–250 km） and decreases at the low and high latitudes（e.g., ~35 km at altitudes of 200–250 km）.The horizontal wavelength shows a similar result（e.g., ~1400 km in the mid-latitudes and ~800 km at the low and high latitudes）.
基金supported by the State Key Project of Research and Development Plan (2016YFA0400204)the National Natural Science Foundation of China (U1738133)+3 种基金Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS)Youth Innovation Promotion Association of CASMinistry of Science and Technology of Jiangsu Province (17KJD510001)Changzhou Institute of Technology (YN1611)
文摘DArk Matter Particle Explorer(DAMPE) is a general purpose high energy cosmic ray and gamma ray observatory, aiming to detect high energy electrons and gammas in the energy range 5 Ge V to 10 Te V and hundreds of Te V for nuclei. This paper provides a method using machine learning to identify electrons and separate them from gammas, protons, helium and heavy nuclei with the DAMPE data acquired from 2016 January 1 to 2017 June 30, in the energy range from 10 to 100 Ge V.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175093,11222545,11435006 and 11375092the K.C.Wong Magna Fund of Ningbo University
文摘We use the latest baryon acoustic oscillation and Union 2.1 type Ia supernova data to test the cosmic opacity between different redshift regions without assuming any cosmological models. It is found that the universe may be opaque between the redshift regions 0.35 0.44, 0.44 0.57 and 0.6-0.73 since the best fit values of cosmic opacity in these regions are positive, while a transparent universe is favored in the redshift region 0.57-0.63. However, in general, a transparent universe is still consistent with observations at the lo confidence level.
文摘针对COSMIC(Constellation Observation System of Meteorology Ionosphere and Climate)掩星反演的大气温度和水汽压二级资料,利用常规探空观测和NCEP(National Centers for Environmental Prediction)分析资料分别进行质量检验分析,以揭示反演资料质量的海陆差异、随纬度和高度变化等三维空间特征。结果显示:我国区域反演资料的温度略低于探空观测与NCEP分析资料,温度与水汽压相对于检验资料的均方根误差较小;全球范围内,反演大气温湿资料的质量随高度和纬度的不同而存在明显差异,而且海洋和陆地上质量的水平和垂直分布特征也存在显著不同。总体上看,COSMIC反演大气温湿资料具有良好的可靠性与精确度,可作为我国数值预报资料同化的新资料,反演温湿资料的质量特征也可为COSMIC资料同化的质量控制和垂直稀疏化方案的设计提供科学依据。
文摘使用COSMIC数据分析和管理中心(COSMIC data analysis and archive center,CDAAC)提供的level 1b数据中的掩星事件表和观测路径上的绝对电子含量资料,在假设电离层各层电子密度相同的前提下,对Abel积分公式进行离散化,并使用最小二乘方法求解。其结果与COSMIC所提供的电离层廓线产品符合度较高,且二者的绝对误差的平均值和标准差分别为-1.52×103el/cm3和6.61×103el/cm3,相对误差的平均值和标准差分别为0.5%和2.9%。所使用的方法计算简便,并且精度与COSMIC产品一致。
文摘为研究COSMIC(constellation observing system for meteorology,ionosphere and climate)掩星反演湿温廓线的质量,需对数据误差特性进行量化研究。首先采用线性插值的方法,以时间窗3 h、水平距离300 km为匹配准则,对0.2~30 km各高度层温度的平均偏差和标准差进行统计分析,研究随海拔高、季节和纬度带变化的温度平均偏差特性。然后采用2016年的全球探空数据集分析全球区域的COSMIC湿温廓线质量,以及北温带COSMIC湿温廓线质量随季节变化的特点,探究不同纬度带地区COSMIC掩星湿温廓线质量随纬度变化的特点。结果表明,全球范围内温度平均偏差为-0.16 K,掩星数据和探空站资料精度相当;季节变化的统计量F=0.999 6>0.05,该因素对COSMIC湿温廓线质量影响不显著;纬度带变化的统计量F=0.024 4<0.05,该因素对COSMIC湿温廓线质量有显著影响,尤其是热带地区受水汽影响较大,温度平均偏差处于峰值,偏差高于0.25 K,南温带地区次之。
文摘电离层foF2是短波通信、天波超视距雷达系统所需的关键环境参数,使用2006—2014年COMSIC(constellation observing system for meteorology,ionosphere,and climate)掩星电离层数据和多项式方法,自主构建了高精度全球电离层foF2经验模型,并使用2015—2019年观测数据进行独立检验。本模型结果与建模及独立检验时段电离层foF2观测数据的相关系数分别为0.948和0.937,平均偏差分别为2.38%和3.08%,相对误差分别为11.72%和12.69%。利用该模型研究了电离层foF2时空变化特征,结果表明电离层foF2日夜变化幅度随纬度增加而变大,春秋分季期间南半球日夜变化幅度显著高于北半球,而夏季半球则远低于冬季半球。电离层foF2季节变化幅度随纬度增加而变大,夜间电离层foF2的季节变化以年特征为主,白天则包含了显著的年、半年特征,夜间季节变化幅度明显高于白天,南半球显著高于北半球。电离层foF2中纬槽现象主要出现在春秋分季夜间,经度方向四波结构主要出现在太阳活动低年和春秋分季期间。
文摘多源数据同化是实现电离层天气现报和预报的重要途径.选择参数化电离层模型作为背景模型,基于地基全球卫星导航系统(Global Navigation Satellite System,GNSS)观测以及第二代气象/电离层气候卫星探测系统(Constellation Observing System for Meteorology Ionosphere and Climate 2,COSMIC 2)掩星测量,利用经验电离层模型NeQuick计算得到多源观测数据,结合水平和垂直方向分离的高斯型协方差矩阵及卡尔曼滤波方法实现了中国区域电离层多源数据同化反演.同化结果表明,多源数据同化方法能将观测资料有效地同化到背景模式中从而获得较好的同化结果.与背景模式相比,同化后得到的电离层总电子含量及电子密度误差均显著下降.
