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Two methods for separating the magnetospheric solar wind charge exchange soft X-ray emission from the diffuse X-ray background

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Earth and Planetary Physics 2024年第1期8卷 119-132页

作者： YingJie Zhang TianRan Sun JenniferACarter WenHao Liu Steve Sembay ShuiNai Zhang Li Ji Chi Wang State Key laboratory of space weather National Space Science CenterChinese Academy of SciencesBeijing 100190China College of Earth and Planetary Sciences The University of Chinese Academy of SciencesBeijing 100190China School of Physics and Astronomy The University of LeicesterLeicesterUK Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008China

Solar wind charge exchange(SWCX)is the process of solar wind high-valence ions exchanging charges with neutral components and generating soft ***,detecting the SWCX emission from the magnetosphere is proposed as a new technique to study the magnetosphere using panoramic soft X-ray *** better prepare for the data analysis of upcoming magnetospheric soft X-ray imaging missions,this paper compares the magnetospheric SWCX emission obtained by two methods in an XMM-Newton observation,during which the solar wind changed *** two methods differ in the data used to fit the diffuse X-ray background(DXB)parameters in spectral *** method adding data from the ROSAT All-Sky Survey(RASS)is called the RASS *** method using the quiet observation data is called the Quiet method,where quiet observations usually refer to observations made by the same satellite with the same target but under weaker solar wind *** show that the spectral compositions of magnetospheric SWCX emission obtained by the two methods are very similar,and the changes in intensity over time are highly consistent,although the intensity obtained by the RASS method is about 2.68±0.56 keV cm^(-2)s^(-1)sr^(-1)higher than that obtained by the Quiet *** the DXB intensity obtained by the RASS method is about 2.84±0.74 keV cm^(-2)s^(-1)sr^(-1)lower than that obtained by the Quiet method,and the linear correlation coefficient between the difference of SWCX and DXB obtained by the two methods in diffe rent energy band is close to-1,the diffe rences in magnetospheric SWCX can be fully attributed to the diffe rences in the fitted *** difference between the two methods is most significant when the energy is less than 0.7 keV,which is also the main energy band of SWCX *** addition,the difference between the two methods is not related to the SWCX intensity and,to some extent,to solar wind conditions,because SWCX intensity typically va ries with the

关键词： solar wind charge exchange(SWCX) ROSAT All-Sky Survey(RASS) soft X-ray X-ray imaging magnetosphere

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Hourly land surface temperature retrieval over the Tibetan Plateau using Geo-LightGBM framework: Fusion of Himawari-8 satellite, ERA5 and site observations

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Advances in Climate Change Research 2024年第4期15卷 623-635页

作者： Zhao-Hua LIU Shan-Shan WENG Zhao-Liang ZENG Ming-Hu DING Ya-Qiang WANG Zhehao LIANG Civil and Surveying&Mapping Engineering Jiangxi University of Science and TechnologyGanzhou 341000China State Key laboratory of Severe weather Chinese Academy of Meteoroogical Sciences Beijing 100081China space Geodesy and Geoinformation Technical Unviersity of BerlinBerlin 10623Germany

The Tibetan Plateau(TP)is highly sensitive to even minor fluctuations in land surface temperature(LST),which can result in permafrost melting and degradation of alpine grasslands,leading to serious ecological ***,it is crucial to have high-temporal-resolution and seamless hourly estimating and monitoring of LST for a better understanding of climate change on the ***,we employed Himawari-8 satellite,Digital Elevation Model(DEM),ERA5 reanalysis and meteorological station observations data to develop a new LightGBM framework(called Geo-LightGBM)for estimating LST on the TP,and then analyzed the spatiotemporal variations of those ***-LightGBM demonstrated excellent LST estimation accuracy,with an R2(coefficient of determination)of 0.971,RMSE(root-mean-square error)of 2.479℃,and MAE(mean absolute error)of 1.510℃.The estimated LST values for the year 2020 agreed well with observed values,with remarkable differences in hourly LST ***,the estimated LST was more accurate than that from ***,there were two high LST centers,located in the Yarlung Zangbo River Basin and the Qaidam Basin,and a low LST center located in the central *** SHAP(SHapley Additive exPlanations)and correlation analyses revealed DSCS(the mean ground downward shortwave radiation under clear-sky conditions)to be the most importantly input variable for estimating *** dummy variables(e.g.,longitude,latitude,DEM)were also found to be crucial for model accuracy *** findings indicate the potential for constructing a high-precision and seamless 24-h LST real-time retrieval and monitoring platform for the TP by combining satellite and China's independently developed CLDAS(China Land Data Assimilation System)data in future.

关键词： Tibetan Plateau Himawari-8 ERA5 Land surface temperature Geo-LightGBM

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Latest Scientific Results of China's Lunar and Deep space Exploration(2022–2024)

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空间科学学报 2024年第4期44卷 622-632页

作者： XU Lin LI Lei LIU Jianzhong LIN Honglei LI Yang LIU Yang XIE Lianghai ZHANG Jinhai QIAO Fuhao HAN Juanjuan ZOU Yongliao General Office of the Lunar and Deep space Exploration Chinese Academy of SciencesBeijng 100190 State Key laboratory of space weather National Space Science CenterChinese Academy of SciencesBeijing 100190 Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081 Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029

China has successfully launched six lunar probes so *** Chang'E-1 to Chang'E-4,they completed the circling,landing and roving exploration,of which Chang'E-4 was the first landing on the far side of the Moon in human ***'E-5 was launched in December 2020,bringing back 1731 g of lunar soil *** the detailed analysis of the samples,the scientists understand the history of late lunar volcanism,specifically extending lunar volcanism by about 800 million to 1 billion years,and proposed possible *** addition,there are many new understandings of space weathering such as meteorite impacts and solar wind radiation on the ***'s first Mars exploration mission Tianwen-1 was successfully launched in July *** the study of scientific data,a number of important scientific achievements have been made in the topography,water environment and shallow surface structure of *** paper introduces the main scientific achievements of Chang'E-4,Chang'E-5 and Tianwen-1 in the past two years,excluding technical and engineering *** to the large number of articles involved,this paper only introduces part of the results.

关键词： Lunar and deep space exploration of China Chang’E-4 mission Chang’E-5 mission Tianwen-1 mission

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Fusion SST from Infrared and Microwave Measurement of FY-3D Meteorological Satellite

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Journal of Tropical Meteorology 2024年第1期30卷 89-96页

作者：张淼徐娜陈林 National Satellite Meteorological Center/National Center for space weather Beijing 100081 China Innovation Center for Fengyun Meteorological Satellite(FYSIC) Beijing 100081 China Key laboratory of Radiometric Calibration and Validation for Environmental Satellites China Meteorological AdministrationBeijing 100081 China

Sea surface temperature(SST)is one of the important parameters of global ocean and climate research,which can be retrieved by satellite infrared and passive microwave remote sensing *** satellite infrared SST offers high spatial resolution,it is limited by cloud *** the other hand,passive microwave SST provides all-weather observation but suffers from poor spatial resolution and susceptibility to environmental factors such as rainfall,coastal effects,and high wind *** achieve high-precision,comprehensive,and high-resolution SST data,it is essential to fuse infrared and microwave SST *** this study,data from the Fengyun-3D(FY-3D)medium resolution spectral imager II(MERSI-II)SST and microwave imager(MWRI)SST were ***,the accuracy of both MERSIII SST and MWRI SST was verified,and the latter was bilinearly interpolated to match the 5km resolution grid of MERSI *** pretreatment and quality control of MERSI SST and MWRI SST,a Piece-Wise Regression method was employed to correct biases in MWRI ***,SST data were selected based on spatial resolution and accuracy within a 3-day window of the analysis ***,an optimal interpolation method was applied to fuse the FY-3D MERSI-II SST and MWRI *** results demonstrated a significant improvement in spatial coverage compared to MERSI-II SST and MWRI ***,the fusion SST retained true spatial distribution details and exhibited an accuracy of–0.12±0.74℃compared to OSTIA *** study has improved the accuracy of FY satellite fusion SST products in China.

关键词： SST data fusion FY3 infrared microwave

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The dawn−dusk asymmetry in mesosphere and lower thermosphere temperature disturbances during geomagnetic storms at high latitude

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Earth and Planetary Physics 2024年第2期8卷 356-367页

作者： GuanChun Wei JianYong Lu Fen Tang JingYuan Li Meng Sun Institute of space weather School of Atmospheric PhysicsNanjing University of Information Science&TechnologyNanjing 210044China College of Information and Communication National University of Defense TechnologyWuhan 430019China

Utilizing observations by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument,we quantitatively assessed the dawn-dusk asymmetry in temperature disturbances within the high-latitude mesosphere and lower thermosphere(MLT)during the main phase of geomagnetic storms in this *** analysis of five geomagnetic superstorm events indicated that during the main phase,negative temperature disturbances were more prevalent on the dawn side than on the dusk side in the high-latitude MLT *** of a statistical analysis of 54 geomagnetic storm events also revealed a notable disparity in temperature disturbances between the dawn and dusk *** high latitudes,38.2%of the observational points on the dawn side exhibited negative temperature disturbances(less than−5 K),whereas on the dusk side,this percentage was only 29.5%.In contrast,at mid-latitudes,these proportions were 34.1%and 36.5%,respectively,showing no significant *** also conducted a statistical analysis of temperature disturbances at different altitudes,which revealed an increase in the proportion of warming disturbances with ***,the proportion of cooling disturbances initially rose with altitude,reaching a peak around 105 km,and subsequently *** temperature disturbance differences could be explained by the day-night asymmetry in vertical wind disturbances during storm conditions.

关键词： dawn dusk asymmetry SABER(Sounding of the Atmosphere using Broadband Emission Radiometry) geomagnetic storms mesosphere and lower thermosphere

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Physics-informed Neural Network for Force-free Magnetic Field Extrapolation

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Research in Astronomy and Astrophysics 2024年第10期24卷 159-169页

作者： Yao Zhang Long Xu Yihua Yan State Key laboratory of space weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 101408China Faculty of Information Science and Engineering Ningbo UniversityNingbo 315211China

In this paper,we propose a physics-informed neural network extrapolation method that leverages machine learning techniques to reconstruct coronal magnetic *** enhance the classical neural network structure by introducing the concept of a quasi-output layer to address the challenge of preserving physical constraints during the neural network extrapolation ***,we employ second-order optimization methods for training the neural network,which are more efficient compared to the first-order optimization methods commonly used in classical machine *** approach is evaluated on the widely recognized semi-analytical model proposed by Low and *** results demonstrate that the deep learning method achieves high accuracy in reconstructing the semianalytical model across multiple evaluation *** addition,we validate the effectiveness of our method on the observed magnetogram of active region.

关键词： Sun:magnetic fields Sun:corona magnetohydrodynamics(MHD)

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Consecutive narrow and broad quasi-periodic fast-propagating wave trains associated with a flare

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 200-211页

作者： Xinping Zhou Yuandeng Shen Chengrui Zhou Zehao Tang Ahmed Ahmed Ibrahim College of Physics and Electronic Engineering Sichuan Normal UniversityChengdu 610068China State Key laboratory of space weather Chinese Academy of SciencesBeijing 100190China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Department of Physics and Astronomy College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

The excitation mechanism of coronal quasi-period fast-propagating(QFP)wave trains remains *** Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory observations,we study a narrow and a broad QFP wave trains excited one after another during the successive eruptions of filaments hosted within a fan-spine magnetic system on October 20,*** consecutive occurrence of these two types of QFP wave trains in the same event provides an excellent opportunity to explore their excitation mechanisms and compare their physical *** observational results reveal that narrow and broad QFP wave trains exhibit distinct speeds,periods,energy fluxes,and relative intensity amplitudes,although originating from the same active region and being associated with the same GOES C2.9 *** wavelet analysis,we find that the narrow QFP wave train shares a similar period with the flare itself,suggesting its possible excitation through the pulsed energy release in the magnetic reconnection process that generated the accompanying *** the other hand,the broad QFP wave train appears to be associated with the energy pulses released by the successive expansion and unwinding of filament ***,it is plausible that the broad QFP wave train was also excited by the sequential stretching of closed magnetic field lines driven by the erupting *** findings shed light on the different excitation mechanisms and origins of the QFP wave trains.

关键词： narrow wave excitation

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Improving Satellite-Retrieved Cloud Base Height with Ground-Based Cloud Radar Measurements

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Advances in Atmospheric Sciences 2024年第11期41卷 2131-2140页

作者： Zhonghui TAN Ju WANG Jianping GUO Chao LIU Miao ZHANG Shuo MA College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China State Key laboratory of Severe weather Chinese Academy of Meteorological SciencesBeijing 100081China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China Key laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration School of Atmospheric PhysicsNanjing University of Information Science&TechnologyNanjing 210044China National Satellite Meteorological Center(National Center for space weather) China Meteorological AdministrationBeijing 100081China

Cloud base height(CBH) is a crucial parameter for cloud radiative effect estimates, climate change simulations, and aviation guidance. However, due to the limited information on cloud vertical structures included in passive satellite radiometer observations, few operational satellite CBH products are currently available. This study presents a new method for retrieving CBH from satellite radiometers. The method first uses the combined measurements of satellite radiometers and ground-based cloud radars to develop a lookup table(LUT) of effective cloud water content(ECWC), representing the vertically varying cloud water content. This LUT allows for the conversion of cloud water path to cloud geometric thickness(CGT), enabling the estimation of CBH as the difference between cloud top height and CGT. Detailed comparative analysis of CBH estimates from the state-of-the-art ECWC LUT are conducted against four ground-based millimeter-wave cloud radar(MMCR) measurements, and results show that the mean bias(correlation coefficient) is0.18±1.79 km(0.73), which is lower(higher) than 0.23±2.11 km(0.67) as derived from the combined measurements of satellite radiometers and satellite radar-lidar(i.e., Cloud Sat and CALIPSO). Furthermore, the percentages of the CBH biases within 250 m increase by 5% to 10%, which varies by location. This indicates that the CBH estimates from our algorithm are more consistent with ground-based MMCR measurements. Therefore, this algorithm shows great potential for further improvement of the CBH retrievals as ground-based MMCR are being increasingly included in global surface meteorological observing networks, and the improved CBH retrievals will contribute to better cloud radiative effect estimates.

关键词： cloud base height passive radiometer ground-based cloud radar remote sensing

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Cloud-Type-Dependent 1DVAR Algorithm for Retrieving Hydrometeors and Precipitation in Tropical Cyclone Nanmadol from GMI Data

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Advances in Atmospheric Sciences 2024年第3期41卷 407-419页

作者： Linjun HAN Fuzhong WENG Hao HU Xiuqing HU School of the Environment China University of Geosciences(Wuhan)Wuhan 430074China Chinese Academy of Meteorological Sciences Beijing 100081China CMA Earth System Modeling and Prediction Centre Beijing 100081China Key laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center(National Center for Space Weather)of CMABeijing 100081China

Understanding the structure of tropical cyclone(TC)hydrometeors is crucial for detecting the changes in the distribution and intensity of *** this study,the GMI brightness temperature and cloud-dependent 1DVAR algorithm were used to retrieve the hydrometeor profiles and surface rain rate of TC Nanmadol(2022).The Advanced Radiative Transfer Modeling System(ARMS)was used to calculate the Jacobian and degrees of freedom(△DOF)of cloud water,rainwater,and graupel for different channels of GMI in convective *** retrieval results were compared with the Dual-frequency Precipitation Radar(DPR),GMI 2A,and IMERG *** is shown that from all channels of GMI,rain water has the highest△DOF,at *** to the radiance Jacobian to atmospheric state variables,cloud water emission dominates its *** rain water,the emission of channels 1–4 dominates *** with the GMI 2A precipitation product,the 1DVAR precipitation rate has a higher correlation coefficient(0.713)with the IMERG product and can better reflect the location of TC *** the TC eyewall,the highest radar echo top indicates strong *** the melting layer where Ka-band attenuation is strong,the double frequency difference of DPR data reflects the location of the *** DPR drop size distribution(DSD)product shows that there is a significant increase in particle size below the melting layer in the spiral rain ***,the particle size may be one of the main reasons for the smaller rain water below the melting layer retrieved from 1DVAR.

关键词： cloud-dependent 1DVAR hydrometeor precipitation GMI DPR

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Recognition of Organizational Morphology of Mesoscale Convective Systems Using Himawari-8 Observations

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Journal of Tropical Meteorology 2024年第3期30卷 289-305页

作者： SHOU Yi-xuan ZHANG Su-zhao LU Feng Key laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center(National Center for Space Weather)China Meteorological AdministrationBeijing 100081 China Innovation Center for FengYun Meteorological Satellite(FYSIC) Beijing 100081 China Key laboratory for Meteorological Disaster Monitoring and Early Warning and Risk Management of Characteristic Agriculture in Arid Regions Yinchuan 750002 China Ningxia Key laboratory of Meteorological Disaster Prevention and Mitigation Yinchuan 750002 China

The onset,evolution,and propagation processes of convective cells can be reflected by the organizational morphology of mesoscale convective systems(MCSs),which are key factors in determining the potential for heavy *** paper proposed a method for objectively classifying and segmenting MCSs using geosynchronous satellite *** of the product relative to the classification in radar composite reflectivity imagery indicates that the algorithm offers skill for discriminating between convective and stratiform areas and matched 65%of convective area identifications in radar imagery with a false alarm rate of 39%and an accuracy of 94%.A quantitative evaluation of the similarity between the structures of 50 MCSs randomly obtained from satellite and radar observations shows that the similarity was as high as 60%.For further testing,the organizational modes of the MCS that caused the heavy precipitation in Northwest China on August 21,2016(hereinafter known as the“0821”rainstorm)were *** was found that the MCS,accompanied by the“0821”rainstorm,successively exhibited modes of the isolated cell,squall line with parallel stratiform(PS)rain,and non-linear system during its life *** them,the PS mode might have played a key role in causing this *** findings are in line with previous studies.

关键词： mesoscale convective system satellite organizational morphology extremely heavy precipitation

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