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| 1 | Using the GPS observations to reconstruct the ionosphere three-dimensionally with an ionospheric data assimilation and analysis system(IDAAS)显示文摘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 Asia.The 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 reconstruction.The inversed NmF2 and vertical TEC both demonstrate great improvement of agreement with those observed from ionosondes and TOPEX satellite independently. | YU Tao MAO Tian WANG YunGang ZENG ZhongCao WANG JingSong FANG HanXian | 2014 | Science China(Technological Sciences)2014，57，11： | 6 |
| 2 | HF waves heating ionosphere F-layer显示文摘为了预言并且评估 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% 。 | FANG HanXian WANG SiCheng SHENG Zheng | 2012 | Chinese Science Bulletin2012，57，31： | 2 |
| 3 | A new sequential data assimilation method显示文摘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. | HAN YueQi ZHANG YaoCun WANG YunFeng YE Song FANG HanXian | 2009 | Science China(Technological Sciences)2009，52，4： | 1 |
| 4 | Long-term trends in foF2 over Moscow ionosonde station: Its estimate and origins显示文摘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 foF2.Possible 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 field.We find that this slope depends on local time and seasons.There 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 winter.Finally,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. | FANG HanXian WENG LiBin YANG ShengGao WANG SiCheng | 2012 | Chinese Science Bulletin2012，57，12： | 1 |
| 5 | Application of ERA5 Reanalysis to the Construction of Initial Conditions for WACCM Simulations显示文摘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. | WANG Yegui JING Wenqi CUI Yuanyuan CAI Qifa LAN Weiren FANG Hanxian WENG Libin NIU Jun | 2018 | 空间科学学报2018，38，4： | 1 |
| 6 | Establishment of N_mF_2 empirical model in the northern hemisphere based on COSMIC occultation data显示文摘Ionospheric peak value of F2 layer(Nm F2)is an important parameter in the ionosphere,which has important applications in short-wave communication,ionospheric modeling and so on.In this paper,the empirical orthogonal function(EOF)decomposition method is used to analyze the Nm F2obtained from the occultation data.Daily spatial distribution of Nm F2at the same time is relatively even.Variance of first modal is much larger than the other modals.A local wavelet power spectrum(LWPS)method is applied to analysis the cycle of F10.7index and time coefficient of first modal.The result shows that they have similar cycle distribution,indicating that F10.7index is the main factor affecting variation of Nm F2.A function is established between the tine coefficient of first modal and F10.7index,average F10.7index value of early 81 days fp by least squares method.The results show that contribution coefficient of fp is negative which indicates that fp has an inert effect existing in the ionosphere.Contribution coefficient of F10.7is positive,which is consistent with the fact that it has an anomaly in winter/spring seasons.In summary,it is feasible to establish a mid-latitude empirical Nm F2model in northern hemisphere based on occultation data and EOF decomposition method. | NIU Jun FANG HanXian WENG LiBin | 2014 | Science China(Technological Sciences)2014，57，2： | 1 |
| 7 | Investigation of the mesospheric temperature over Fort Collins region显示文摘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 km,but reverse below 95 km,and there is a cooler region below 185 K around 97 km in August.The largest seasonal variation is 39.2 K at 81 km,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 km,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. | FAN Xin WENG LiBin ZHANG JianBin FANG HanXian XIE YanQiong | 2014 | Science China(Technological Sciences)2014，57，8： | 0 |
| 8 | Spectra of L-band ionospheric scintillation over Nanjing显示文摘We report the spatiotemporal statistical characteristics of amplitude scintillation over Nanjing.A FFT method for computing scintillation intensity power spectra is briefly described.Using this method,the data with ISATM in Nanjing is analyzed.Spectra characteristic is presented and the irregularities property is discussed preliminarily.The results reveal that the power spectra obtained for Nanjing is consistent with theoretical modeling.At frequencies below the Fresnel frequency,the power density plotted on log-log scale is almost constant whereas above it asymptotes to a straight line.The spectral index ranges from 1.71 to 1.92,which has positive correlation with the S 4 index.Finally,the average drift velocity of irregularities is computed assumably and compared with that obtained for Xinxiang and Haikou. | FANG HanXian YANG ShengGao WANG SiCheng | 2012 | Chinese Science Bulletin2012，57，25： | 0 |
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