## Current Issue 2022, Volume 42,  Issue 3

Display Method:
2022, 42(3): 333-339. doi: 10.11728/cjss2022.03.210107004
Abstract:
Sunspots are the regions with stronger magnetic field in the solar photosphere and most of solar eruptions occur in complex sunspot groups. Mount Wilson magnetic classification is one of the most popular sunspots classification methods, which is of great significance to the study of solar eruptions. In recent years, with the rapid development of China’s space industry, space physics research has entered the era of big data. Deep learning methods for processing space science data are springing up. In this study, based on the SDO/HMI SHARP continuum and magnetogram data during 2010－2017, we propose to apply deep learning for the image recognition of Mount Wilson magnetic type of sunspots. The results show that Xception has a productive performance in the identification of the sunspots magnetic types in solar active regions. The F1 score of sunspots group of α exceeds 96%, that of β is more than 93%, and that of other types is more than 84%.
2022, 42(3): 340-345. doi: 10.11728/cjss2022.03.210310025
Abstract:
Solar proton event is a space weather phenomenon caused by energetic particles ejected and propagated into near-Earth space during bursts of solar activity. These high-energy particles can cause serious harm to spacecraft and astronauts, therefore, accurate short-term forecasting of solar proton events is very necessary as part of disaster prevention for space activities. The short-time forecasting of solar proton events still faces a lot of challenges, one of which is the high false alarm rate. To solve this problem, we adopted a whole new set of methods-machine learning. As a branch of computer science, many excellent algorithms have emerged in the field of machine learning in recent years, and have achieved successful applications in many fields. In this study, an ensemble model based on 8 widely used machine learning models is established to make precise forecasting of solar proton events. An experiment on the 23rd solar cycle shows that this model gets a probability of detection of 80.95% and a false alarm rate of 19.05%.
2022, 42(3): 346-356. doi: 10.11728/cjss2022.03.210406045
Abstract:
Geomagnetic storm is an important disaster event in space weather, which can affect satellite orbit and ground power system. At present, in the solar wind-magnetosphere system, most studies focus on the linear relationships analyzed by the correlation coefficient. However, transfer entropy can provide powerful model-free directed statistics, which can be used to analyze non-linear relationships that cannot be detected by traditional correlation analysis and model hypothesis. The hourly resolution data of solar activity cycle 23 and 24 were used to analyze the large time scale. The information transmission of solar wind and geomagnetic has a bimodal distribution, which is consistent with the solar activity level. Using the minute resolution data of 93 geomagnetic storms from 2010 to 2018 for small time scale analysis, the results show that E, ${{\rm{IMF}}B}_{z}$ have strong information transmission to the geomagnetic Sym-H parameter when the time delay is 60 minutes, while ${v}_{\mathrm{s}\mathrm{w}}$, ${T}_{\mathrm{s}\mathrm{w}}$, ${D}_{\mathrm{s}\mathrm{w}}$, B, ${P}_{\mathrm{s}\mathrm{w}}$ are lower. It provides the basis for parameter selection and prediction range determination for solar wind-geomagnetic model construction.
2022, 42(3): 357-365. doi: 10.11728/cjss2022.03.210401042
Abstract:
The Total Electron Content (TEC) of the ionosphere is not only one of the key parameters to analyze the shape of the ionosphere, but also provides an important support for the navigation, positioning and other space applications to eliminate the additional ionospheric delay. Due to the temporal and spatial variation characteristics of ionospheric TEC, an ionospheric TEC hybrid deep learning model based on Causal convolution and Long Short-Term Memory network is proposed in this paper. The solar activity index F10.7, the geomagnetic activity index Dst and the historical ionospheric TEC data are used as feature inputs to predict the TEC 24 hours in advance. Using CODE TEC data covering the low and high solar activities during 2005－2013, the performance of the model is comprehensively evaluated at Beijing station (40°N, 115°E), Wuhan station (30.53°N, 114.36°E) and Haikou station (20.02°N, 110.38°E). The results show the correlation coefficients between the predicted TEC values of the three stations and the actual values under different solar activity conditions are greater than 0.87, and most root mean square errors concentrated within 1 TECU. The prediction accuracy of the model is related to latitude, solar activity, geomagnetic activity and seasonal variation. Compared with the prediction model composed of LSTM network, the root mean square error of the proposed model is reduced by 15%, which provides a valuable reference for the practical application of the ionospheric TEC prediction.
2022, 42(3): 366-375. doi: 10.11728/cjss2022.03.210325037
Abstract:
A method to calculate the Total Electron Content (TEC) of the global ionosphere is proposed based on the Automatic Identification System (AIS) for ships on board. Specifically, The Faraday rotation angle of AIS signal passing through the ionosphere is measured by carrying two mutually perpendicular linearly polarized antennas on the satellite, and then estimate TEC by the relationship between the Faraday rotation angle and the TEC. The experimental validation based on the AIS data from Tiantuo V satellite is carried out, and the effects of hardware equipment errors and observation parameter errors on the results are analyzed. Experiments show that the difference between the TEC value measured by the method and by the Global Positioning System (GPS) is 0.762 TECU on average, which proves the feasibility of this method. Compared with the existing TEC measurement methods, this method only needs to use the existing AIS system without deploying ground stations, which can significantly improve the data update rate.
2022, 42(3): 376-382. doi: 10.11728/cjss2022.03.210406043
Abstract:
Based on the statistical analysis of the dataset recorded by ionosonde at Wuhan station (114.61°E, 30.53°N) in 2018, characteristics of sporadic E layer over Wuhan area are studied. It is found that the critical frequency of sporadic E layer was the highest in summer, a secondary enhancement in winter, and it was very low in spring and autumn; and it was highest around noon, a secondary enhancement at sunset and the lowest before sunrise. Using the specified dynamics Whole Atmosphere Community Climate Model-extended (SD-WACCM-X) to simulate the average wind field over Wuhan at a height of 90～140 km in 2018, to reveal the formation mechanism of sporadic E layer. The results show that the semi-diurnal tidal component may induce a semi-diurnal change in the critical frequency of the sporadic E layer, and the diurnal tidal component induces a diurnal change in the critical frequency of the sporadic E layer. It is also found that the intensity of the sporadic E layer may be related to the wind shear at a height of 120 km in the zonal wind field.
2022, 42(3): 383-395. doi: 10.11728/cjss2022.03.210303022
Abstract:
The Quasi-zero Wind Layer is a transition region with low zonal wind speed in the lower stratosphere, which is important reference for the development and utilization of the near space (20~100 km) and has been attracting worldwide interest. In this paper, the whole country (China) is divided into five regions (15°N－20°N, 20°N－25°N, 25°N－30°N, 30°N－40°N, and 40°N－50°N) based on the L-band radar soundings secondly data of stations from January 2010 to December 2019. The structural characteristics of the Quasi-zero Wind Layer in China and its variations with latitude and season are analyzed. The single/double Quasi-zero Wind Layer is defined according to the different observed wind fields from the data. Results show that the overall distribution of the single/double Quasi-zero Wind Layer in the five regions is generally different distinguished from the separating latitude of 25°N: The single Quasi-zero Wind Layer mainly appears in summer to the north of 25°N. The double Quasi-zero Wind Layer mainly appears to the south of 25°N from October to May of the next year. The average maintenance heights of the single/double Quasi-zero Wind Layer increase with the increasing latitude, and its thickness shows mainly bimodal variation. The occurrence and maintenance days of the single Quasi-zero Wind Layer are more than that of the double Quasi-zero Wind Layer , and the maintenance days in the north of 30°N are significantly prolonged.
2022, 42(3): 396-402. doi: 10.11728/cjss2022.03.210527065
Abstract:
Data obtained from near space meteorological rocket sounding in northwest China in winter compared with that from empirical model MSIS00, MERRA reanalysis and satellite TIMED/SABER in order to analyze the meteorological rocket data reliability. Different kinds of temperature correction were calculated. Analysis shows temperature and density variation trends from all data sources are almost the same. However, compared with MSIS00, data from rockets and satellites are more accurate and have many similar details. Meteorological rocket’s wind data matches MERRA well. Deviation of these two data sources changes around 0. However, measured wind data is different from HWM07, and obviously stronger in the middle stratosphere. Besides, meteorological rocket observes strong wind changes around 22 km and 45 km. Among all kinds of temperature error, air heating, temperature hysteresis, heat transfer and current heating contributes a lot, reducing as altitude decreases. Comprehensive comparison results show that meteorological rocket data is effective and reliable, but the data processing method especially error correction needs to be improved.
2022, 42(3): 403-413. doi: 10.11728/cjss2022.03.210531066
Abstract:
At present, research on the fair-weather atmospheric electric field are mostly carried out on a single region or on a 2～3 years time scale, while the analysis and comparison on multiple observation stations with different longitude and latitude and large time scale are few. In this study, the observational data of near-surface fair-weather atmospheric electric field from five stations of the Meridian Project in recent ten years were compared and analyzed on three different time scales: annual variation, seasonal variation and diurnal variation. The results show that the peak and valley types of the average daily fair-weather atmospheric electric field are different at different latitudes, and the wave peaks at Zhaoqing Station in Guangzhou, Jiufeng Station in Wuhan and Mohe Station in Heilongjiang tend to shift to the left or the right year by year. Located in the low latitudes in Zhaoqing, Guangzhou, Wuhan, Chengdu PI county stand the Jiufeng station sites, such as nearly a decade of sunny overall atmospheric electric field amplitude shows the characteristics of the change of the reduced year by year, while the electric field amplitude of Changchun Nong'an Station and Heilongjiang Mohe Station in the middle and high latitudes showed an annual increase in the overall trend, and the annual changes were linear. The occurrence time of maximum crest is negatively correlated with geographical longitude, but positively correlated with geographical latitude. There was no obvious latitude effect at each station in the last ten years. The daily average level of the fair-weather atmospheric electric field is higher in winter and lower in summer, and the minimum and maximum values of the daily average fair-weather electric field are approximately normally distributed in all seasons; the variation of the minimum and maximum values is generally consistent on both annual and seasonal time scales. The results reveal the variation characteristics of fair-weather atmospheric electric fields on different time scales.
2022, 42(3): 414-421. doi: 10.11728/cjss2022.03.210513053
Abstract:
Atmospheric electric field is closely related to the thunderstorm, climate change, air pollution and solar activity. The detection of atmospheric electric field altitude distribution on special terrain is of great significance for the research of atmospheric electricity. On 12 September 2020, the Honghu special team of Chinese Academy of Sciences mounted the atmospheric electric field instrument on the air sounding balloon, and carried out the detection experiment of the high distribution of atmospheric electric field in the Dachaidan area of Haixi Mongolian-Tibetan Autonomous Prefecture in Qinghai Province. This paper has introduced the electric field instrument, experimental process, experimental results and discussion. The convex part in the middle of the atmospheric electric field curve corresponds to the electric field instrument passing through the clouds. The curve was devided into three sections. These three sections were fitted respectifly. The results show that the main influencing factors of the atmospheric electric field at different altitudes are different, and their distribution laws are also different. In addition, charged clouds can make the overall intensity of the atmospheric electric field increased, while the altitude distribution of the atmospheric electric field in the charged cloud layer is still in accordance with the exponential law.
2022, 42(3): 422-436. doi: 10.11728/cjss2022.03.210611069
Abstract:
Space weather events caused by solar activities such as flares and Coronal Mass Ejections (CMEs) can affect the magnetosphere of the Earth, the middle and upper atmosphere, ionosphere, the safety of satellite operation and human health directly or indirectly. Therefore, the prediction of space weather events is particularly important. In the case of sparse observation and asynchronous sampling, data assimilation can increase the prediction ability of the model, self-consistent analysis of model variables can be carried out, and the introduction of data assimilation method in numerical prediction can improve the reliability of the prediction. This paper mainly introduces the application of data assimilation in the atmosphere, ionosphere, magnetosphere, the Sun and other planets from the perspective of data assimilation methods. The potential applications of data assimilation in space weather in the future are also discussed.
2022, 42(3): 437-447. doi: 10.11728/cjss2022.03.210123036
Abstract:
In the habitable confined space, hydrogen (H2), the by-product of water electrolysis to provide breathing oxygen to crews, and crew’s exhaled carbon dioxide (CO2) are the two surplus gases which should be eliminated for maintenance of atmospheric balance and protection of crew’s life safety. Catalytic synthesis of methanol (CH3OH) from H2 and CO2 is one of the best ways to eliminate surplus H2 and CO2 in manned confined space. The conclusions drawn through reaction modeling and characteristic analysis can guide the control of the reaction process, which is conducive to maintaining the atmospheric balance in confined space. In this paper, based on the established material calculation model and temperature one-dimensional heterogeneous model, the reaction characteristics of catalytic synthesis of methanol from H2 and CO2 under different reaction pressures, coolant temperatures, and CO2 to CO ratios were studied. Results show that the increase of reaction pressure, the growth of coolant temperature, and the decrease of CO2 to CO ratio in inlet gas can all promote the increases of reaction rate, methanol synthesis rate, and the maximum temperatures of catalyst and reactant. Besides, in order to keep the catalyst maximum temperature within a reasonable reaction range (lower than 573.15 K), the reaction pressure should not be higher than 8 MPa, the coolant temperature is not higher than 538.15 K, and the ratio of CO2 to CO is not less than 1.
2022, 42(3): 448-454. doi: 10.11728/cjss2022.03.210601027
Abstract:
Vaporized metal has been released in the ionosphere for artificially creating plasma clouds, which can realize or enhance the reflection and scattering of radio waves, thereby affecting the propagation of electromagnetic waves in the information system, and it is currently a research hotspot of emergency communication. Only the metal released in the gaseous form can sufficiently interact with the ionosphere to generate an enhanced electron density region. In the early days, a large number of studies on the release of metal gases were carried out, and the releases mainly used alkali metals and alkaline Earth metals. The mechanism by which these metals generate electron density enhancement is mainly photoionization (the effect is obvious during the day, and the nighttime effect is not obvious). In this study, lanthanide metals were selected as new releasers. Taking the lanthanide metal Samarium (Sm) as an example, a theoretical model of the self-propagating combustion synthesis reaction of Titanium Boron (Ti-B) and Titanium Carbon (Ti-C) for gasifying Sm was established. Through theoretical calculations, the pure heat release and the maximum efficiency of gasifying Sm were obtained for the two self-propagating synthesis reaction systems. According to the theoretical research results, the experimental research on the gasification of Sm in two reaction systems is carried out. The experimental results verify the correctness of the theoretical analysis. It gets rid of the disadvantage that electron density enhancement mainly relies on photoionization, and provides a kind of all-weather method of releasing electron density.
2022, 42(3): 455-462. doi: 10.11728/cjss2022.03.210611070
Abstract:
Liquid xenon has low temperature, low latent heat of vaporization and high dynamic viscosity. Due to depressurization or heating, liquid xenon is prone to phase change, forming gas-liquid two-phase flow in the pipeline and the tank, thus reducing the filling ratio of the tank. Therefore, it is necessary to understand the influence factors of the filling ratio of the tank during the refueling process. The zero dimensional lumped parameter model is used to model and simulate the liquid xenon refueling system. Based on AMESim, the filling ratio of the tank in the process of filling liquid nitrogen with no-vent filling is calculated, which is close to the previous experimental results. A liquid xenon refueling system was built based on AMESim, and the filling ratio of the tank was calculated under different inlet subcooling, inlet pressure, pipeline diameter, pipeline wall temperature and tank heat flow. Results show that under the same filling time, increasing the inlet subcooling and the inlet pressure can both improve the filling ratio of the tank, while heating of the pipeline and tank will reduce the filling ratio of the tank.
2022, 42(3): 463-475. doi: 10.11728/cjss2022.03.210126013
Abstract:
Momentum transfer factor β is the key factor to evaluate effect of kinetic impact. In this paper, theoretical model of momentum transfer factor in kinetic impact is investigated, as well as the influence of impactor properties and small body structure properties on the factor. Meanwhile, the crater effect and momentum transfer factor of small bodies with different kinetic impact schemes and structural characteristics are studied. Results show that scaling law parameter μ, a coefficient related to strength properties of target material which is obtained by ground experiment fitting, has a great effect on the factor. The velocity/density of impactor and density/surface strength of small body have a great effect on the factor for small body with a single rock structure, while radius of impactor and gravity of small body have a small effect. In the meantime, the value of β is significant. The factor is insensitive to parameters of impactor properties and small body structure properties for small body with a rubble-pile structure, and its value is close to 1. The formation of crater and momentum transfer factor in three different kinetic impact schemes indicates that the initial kinetic energy of impactor has a great influence on the factor. In the same kinetic impact scheme where gravity dominates the crater formation, the momentum transfer factor of a C-complex asteroid is largest followed by S-complex and X-complex. However, when strength dominates crater formation, the factors of all complexes are smaller and basically the same.
2022, 42(3): 476-484. doi: 10.11728/cjss2022.03.210208019
Abstract:
Based on the Beidou radio occultation refractivity data of FY-3D satellite from January to March in 2018, the distribution characteristics of Beidou occultation, data accuracy and statistical characteristics of errors are studied. The Beidou Geostationary Orbit (GEO) occultation is distributed arc-shaped along the satellite orbit in the northern and southern polar regions, the Inclined Geo-Synchronous Orbit (IGSO) occultation forms one large and one small cavity respectively in the low latitude areas of the eastern and western hemispheres to form two cavities, and the Middle-Earth Orbit (MEO) occultation is distributed uniformly around the world. The accuracy of the Beidou occultion refractivity is within the range of 12~32 km in the core area. Compared with the ERA5 reanalysis data, the standard deviation of the average deviation is about 1.5%. In the range of height below 12 km and above 35 km, the standard deviation gradually increases from 1.5% to 6%. The deviation of GEO occultation over 35 km is slightly larger than that of IGSO and MEO occultation, but the standard deviation is smaller than that of these two types of occultation. The standard deviation of the descending occultation above 20 km is higher than that of the ascending occultation, but the area below 20 km is less than that of the ascending occultation. The standard deviation of the Beidou occultation is the smallest in high latitudes, followed by that in low latitudes and the largest in middle latitudes, especially in the middle and lower troposphere. The accuracy and error characteristics of the Beidou radio occultation data are consistent with the GPS radio occultation data, indicating that the Earth atmosphere occultation detection does not depend on the satellite navigation system.
2022, 42(3): 485-491. doi: 10.11728/cjss2022.03.210721079
Abstract:
With the increasing frequency of human space activities and the increasing variety and number of space targets, it is of great scientific value to identify the key features of unknown space targets. By segmentation using auxiliary graphics software, the surface coordinates of sphere, cone and cylinder with a normal vector are built. Based on the satellite simulation toolkit, the target orbit and position parameters are obtained. Combining with isotropic Phong BRDF model and attitude quaternion update model, the apparent magnitudes of these four shape space targets under ground observation conditions are simulated. Simulation results show that the target is affected by the spatial position, shape and attitude in different degrees, and each light curve has its own characteristics. Because the sphere is completely centrosymmetric, the light curve is mainly affected by the space position. Light curve waveforms of the cone, cube and cylinder are mainly influenced by shape, the curve trends are mainly influenced by position, and wave frequencies are mainly influenced by attitude angular rate. By statistical analysis of the data, a prior model can be provided for the subsequent inversion of space target position, attitude and shape.
2022, 42(3): 492-499. doi: 10.11728/cjss2022.03.210315029
Abstract:
GNSS-R interferometric altimetry can be used for meso-scale sea level observation with the advantages of high spatial resolution and high measurement accuracy. Compared with the traditional GNSS-R which uses local code tracking for altimetry, GNSS-R interferometric could effectively improve the altimetry accuracy. Although a lot of researches had been carried out in GNSS-R interferometric altimetry around the world, there are few researches in the application of interferometric altimetry using Beidou-3 signal. This article introduces the basic theory of GNSS-R interferometric altimetry technology and its advantages. Aiming at the application of Beidou-3 signal in interferometric altimetry, a GNSS interferometric altimetry instrument had been developed. The overall architecture and implementation of this new instrument is introduced in this paper. An open-field GNSS-R water surface altimetry experiments was conducted using this instrument. In the experiment, the interferometric waveforms generated from Beidou-3 B1 and B2 signal were obtained for the first time, and were compared with the traditional GPS L1 and Beidou-2 B1 local code tracking waveforms. Finally, the inversion results of the water surface height calculated by the two approaches are compared. The comparison results show that the precision of Beidou-3 system’s interferometric measurement is significantly better than that of GPS L1 and Beidou-2 B1 traditional local code altimetry.