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HF waves heating ionosphere F-layer

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Chinese Science Bulletin 2012年第31期57卷 4036-4042页

作者： fang hanxian WANG SiCheng SHENG Zheng Institute of Meteorology PLA University of Science and TechnologyNanjing 211101China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China

为了预言并且评估 ionospheric 修正份量上，电子温度和密度的效果，不安以不同加热条件被分析，基于包括动量方程，连续性方程和精力方程的一个发达模型。(1 ) 强大的 HF 收音机波浪能引起电子温度显著地增加的结果表演，和最大的不安... 详细信息

为了预言并且评估 ionospheric 修正份量上，电子温度和密度的效果，不安以不同加热条件被分析，基于包括动量方程，连续性方程和精力方程的一个发达模型。(1 ) 强大的 HF 收音机波浪能引起电子温度显著地增加的结果表演，和最大的不安在思考层附近，但是电子密度在这个区域减少；(2 ) 越多在电离层降低中立煤气的密度，越电子温度和密度的 larger 骚乱；越高收音机频率，越多降低电子温度的增长；并且越高收音机力量，越电子温度和密度的 larger 骚乱被引起，但是在收音机力量和骚乱振幅之间没有线性关系；(3 ) 在夜间的不安比在 HF 加热的白天无线电与一样的力量飘动的大；在太阳的最小的电子温度不安在太阳的最大值比那大；并且在春天和秋天的电子温度不安比在冬季和夏天大；(4 ) 与相比低纬度，中间纬度有更小的不安，最大的电子温度不安是 30%( 在冬季的白天) ，并且密度是 5% 。

关键词：电离层F层波加热电子温度扰动分析电子密度 HF 无线电波温度扰动

Determine the physical mechanism and source region of beat wave modulation by changing the frequency of high-frequency waves

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Chinese Physics B 2022年第2期31卷 308-313页

作者： Zhe Guo hanxian fang Farideh Honary College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China Department of Physics Lancaster UniversityLancasterLA14YBUK

This paper introduces a new approach for the determination of the source region of beat wave(BW)*** type of modulation is achieved by transmitting high-frequency(HF)continuous waves with a frequency difference f,where f is the frequency of modulated ELF/VLF(extremely low frequency/very low frequency)waves from two sub-arrays of a high power HF *** the advantages of BW modulation in terms of generating more stable ELF/VLF signal and high modulation efficiency,there exists a controversy on the physical mechanism of BW and its source *** this paper,the two controversial theories,i.e.,BW based on D-E region thermal nonlinearity and BW based on F region ponderomotive nonlinearity are examined for cases where each of these two theories exists exclusively or both of them exist *** to the analysis and simulation results presented in this paper,it is found that the generated VLF signal amplitude exhibits significant variation as a function of HF frequency in different source ***,this characteristic can be utilized as a potential new approach to determine the physical mechanism and source location of BW.

关键词： powerful HF waves ionospheric modulated heating beat wave modulation ELF/VLF waves

Spectra of L-band ionospheric scintillation over Nanjing

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Chinese Science Bulletin 2012年第25期57卷 3375-3380页

作者： fang hanxian YANG ShengGao WANG SiCheng Institute of Meteorology PLA University of Science and TechnologyNanjing 211101China State Key Laboratory of Space Weather Chinese Academy of SeiencesBeijing 100190China

We report the spatiotemporal statistical characteristics of amplitude scintillation over Nanjing.A FFT method for computing scintillation intensity power spectra is briefly *** this method,the data with ISATM in Nanjing is *** characteristic is presented and the irregularities property is discussed *** results reveal that the power spectra obtained for Nanjing is consistent with theoretical *** frequencies below the Fresnel frequency,the power density plotted on log-log scale is almost constant whereas above it asymptotes to a straight *** spectral index ranges from 1.71 to 1.92,which has positive correlation with the S 4 ***,the average drift velocity of irregularities is computed assumably and compared with that obtained for Xinxiang and Haikou.

关键词：电离层闪烁光谱特性南京 L-波段违规行为 FFT方法幅度闪烁统计特征

Long-term trends in foF2 over Moscow ionosonde station: Its estimate and origins

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Chinese Science Bulletin 2012年第12期57卷 1443-1448页

作者： fang hanxian WENG LiBin YANG ShengGao WANG SiCheng Institute of Meteorology People＇s Liberation Army University of Science and Technology Nanjing 211101 China State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing 100190 China

We introduce a new approach,using the International Reference Ionosphere 2007(IRI-2007)model and observations from the Moscow ionosonde station,to analyze the long-term trends of ionospheric *** origins,whether natural or manmade, are discussed.A small but significant residual foF2 trend is found,with-0.76 MHz over the past 50 years,but-0.2 MHz after eliminating the most variations caused by solar and geomagnetic activities and the variational earth's magnetic *** find that this slope depends on local time and *** is a pronounced diurnal negative variation in k(annual mean slope of diurnal variations),with much larger absolute values in the morning than during afternoon or evening;the largest k is about-0.0018 per year in spring,and the smallest trend of about-0.0012 per year occurs in ***,the evidence of crucial influences of geomagnetic activity and the earth's magnetic field on the observed trends,as emphasized by the IRI-2007 empirical model,is confirmed,and the effect of CO2 contributions to the trend is also discussed,by cooling the thermospheric temperature or recombining the electron density.

关键词：参考电离层探测仪莫斯科起源估计地球磁场地磁活动临界频率

A new sequential data assimilation method

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Science China(Technological Sciences) 2009年第4期52卷 1027-1038页

作者： HAN YueQi ZHANG YaoCun WANG YunFeng YE Song fang hanxian Department of Atmospheric Sciences Nanjing UniversityNanjing 210093China Institute of Meteorology PLA University of Science and TechnologyNanjing 211101China Institute of Heavy Rain China Meteorological AdministrationWuhan 430074China

A new sequential data assimilation method named "Monte Carlo H ∞ filter" is introduced based on H ∞ filter technique and Monte Carlo method in this paper. This method applies to nonlinear systems in condition of lacking the statistical properties of observational errors. In order to compare the as- similation capability of Monte Carlo H ∞ filter with that of the ensemble Kalman filter (EnKF) in solving practical problems caused by temporal correlation or spatial correlation of observational errors, two numerical experiments are performed by using Lorenz (1963) system and shallow-water equations re- spectively. The result is that the assimilation capability of the new method is better than that of EnKF method. It is also shown that Monte Carlo H ∞ filter assimilation method is effective and suitable to nonlinear systems in that it does not depend on the statistical properties of observational errors and has better robustness than EnKF method when the statistical properties of observational errors are varying. In addition, for the new method, the smallest level factor founded by search method is flow-dependent.

关键词： sequential data assimilation Monte Carlo H∞ filter correlation of observational errors robustness flow-dependent

Investigation of the mesospheric temperature over Fort Collins region

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Science China(Technological Sciences) 2014年第8期57卷 1562-1567页

作者： FAN Xin WENG LiBin ZHANG JianBin fang hanxian XIE YanQiong Institute of Meteorology and Ocean PLA University of Science and Technology Sate Key Laboratory of Space Weather Chinese Academy of Sciences Unit 63655 of PLA

The nightly mean mesospheric temperature profiles between 80 and 107 km, observed by Na lidar, over Fort Collins, Colorado （41°N, 105°W） from 1990 to 2010, are employed to research the temporal and spatial variations and mesopause. We find that the maximum mean temperature is in summer months above 95 kin, but reverse below 95 kin, and there is a cooler region below 185 K around 97 km in August. The largest seasonal variation is 39.2 K at 81 kin, and the minimum is 6.5 K at 96.5 km. The maximum standard derivation in spring and autumn months are larger than other seasons above 105 kin, but the temperatures in March, June and September are lower than the other months between 82 km and 100 km where winter is the largest season. Moreover, the seasonal variations of the temperature are about 36, 8 and 21 K at 85, 95 and 105 km, respectively, winter is colder and summer is warmer above 97.5 km, but reverse below 92 km. The mesopause height is around 102 km in winter, but 84 km in summer, and the mean speed of decreasing or increasing of the mesopause height is about 5 km/month in spring and autumn months which are about 90 km. The lasting time of the mesopause in winter is near 6 months, longer than other seasons, and the mesopause temperature is about 165 K in cool summer, and 185 K in warm winter.

关键词： Na lidar mesospheric temperature mesopause

Using the GPS observations to reconstruct the ionosphere three-dimensionally with an ionospheric data assimilation and analysis system(IDAAS)

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Science China(Technological Sciences) 2014年第11期57卷 2210-2219页

作者： YU Tao MAO Tian WANG YunGang ZENG ZhongCao WANG JingSong fang hanxian National Center for Space Weather China Meteorological Administration Institute of Geophysics and Geomatics China University of Geosciences College of Meteorological PLA University of Science & Technology

Using an international reference ionosphere(IRI)model as a background ionosphere and applying the Kalman filter to update the state with observations,we develop an ionosphere data assimilation analysis system(IDAAS)to reconstruct a three-dimensional(3D)ionosphere with the GPS slant TEC and ionosonde data over east-south *** preliminary results with the GPS data collected over east-south Asia on 30 June 2005 showed that inversed slant TEC has very good correlation with the observations both for the GPS sites being and not being involved in *** inversed NmF2 and vertical TEC both demonstrate great improvement of agreement with those observed from ionosondes and TOPEX satellite independently.

关键词： ionosphere data assimilation GPS TEC

Application of ERA5 Reanalysis to the Construction of Initial Conditions for WACCM Simulations

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空间科学学报 2018年第4期38卷 460-468页

作者： WANG Yegui JING Wenqi CUI Yuanyuan CAI Qifa LAN Weiren fang hanxian WENG Libin NIU Jun College of Meteorology and Oceanography National University of Defense Technology Nanjing 211101 Institute of Atmospheric Physics Chinese Academy of Science Beijing 100029 Meteorological Observatory of 94758 Troops Ningde 355103 Hebei Met

This study uses ECMWF fifth-generation reanalysis, ERA5, which extends to the mesopause, to construct the Initial Conditions(IC) for WACCM(Whole Atmosphere Community Climate Model) simulations. Because the biases between ERA5 and Sounding of the Atmosphere using Broadband Emission Radiometry(SABER) temperature data are within ±5 K below the lower mesosphere,ERA5 reanalysis is used to construct IC in the lower atmosphere. Four experiments are performed to simulate a Stratospheric Sudden Warming(SSW) event from 5 to 15 February 2016. The simulation using the WACCM default climatic IC cannot represent the sharp meteorological variation during SSW. In contrast, the 0～4 d forecast results driven by ERA5-constructed IC is consistent with ERA5 reanalysis below the middle mesosphere. Comparing with WACCM climatology ICs scheme, the ICs constructing method based on ERA5 reanalysis can obtain 67%, 40%, 22%, 4% and 6% reduction of temperature forecast RMSE at 10 hPa, 1 hPa, 0.1 hPa, 0.01 hPa and 0.001 hPa respectively. However,such improvement is not shown in the lower thermosphere.

关键词： ERA5 reanalysis SABER WACCM Initial Condition Stratospheric Sudden Warming(SSW)

不同波长初始电子密度扰动对扩展F触发效应对比研究

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电波科学学报 2016年第5期31卷 933-940页

作者：高泽方涵先汪四成解放军理工大学气象海洋学院南京211101

基于适合描述中低纬电离层扩展F发展的控制方程组,首次对比分析了不同波长初始电子密度扰动对电离层Spread-F的触发影响,讨论了电离层泡状结构和块状结构不规则体对不同电子密度扰动波长的响应效果.结果发现:无论是以泡状结构为主体还... 详细信息

基于适合描述中低纬电离层扩展F发展的控制方程组,首次对比分析了不同波长初始电子密度扰动对电离层Spread-F的触发影响,讨论了电离层泡状结构和块状结构不规则体对不同电子密度扰动波长的响应效果.结果发现:无论是以泡状结构为主体还是以块状结构为主体的不规则体,短波长扰动相对于长波长扰动更有利于Spread-F的激发;当初始电子密度减弱扰动存在于一侧,而增强扰动存在于另一侧时,与只存在一种情况相比,泡状结构和块状结构同时出现,能够增进彼此的扰动幅度,并且泡状结构不规则体的抬升速度大于块状结构;相同电离层背景下,初始扰动所引起的泡状不规则体和块状不规则体不一定都能得到抬升和发展,两者发展趋势并不一致.

关键词：电子密度扰动 Spread-F 触发泡状不规则体块状不规则体数值模拟