The vehicles at the rising stage are susceptible to being influenced by upper atmospheric wind.The high-altitude wind shear is essential in the rocket design.The synthetical wind vector approach is used to determine the wind shear features from the ground to 30 km in the East Asia region,based on the National Centers for Environment Prediction(NCEP)reanalysis data from 2020 to 2022.The findings indicate a relationship between season,altitude,and horizontal distribution and the maximum wind direction,maximum wind speed,and wind shear.The wind shear from radiosonde observations is used to analyze the difference between true atmospheric wind shear and that from NCEP.NCEP underestimates the wind shear.The attack angles of two simulated launch vehicles in the atmosphere wind are analyzed.The results indicate that wind shear has a significant impact below 5 km and between 7～18 km.These results are helpful to grasp the distribution characteristics of high-altitude wind shear in China and provide a reference for the accurate and safe rocket design.

GNSS ionospheric radio occultation (IRO) is an important technique for remote sensing of Earth’s ionosphere. Previous validation of GNSS IRO has often been based on comparisons with ground-based observations, such as ionosondes or in-situ observations, which are assumed to be true representations of the real ionospheric state. But these reference observations commonly used for validation also have errors of their own, which are often neglected in such comparisons. In this study, we employ the three-cornered hat (3CH) method to analyze error statistics and separate errors present in Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) IRO foF2 observations. This provides a better characterization of the errors since it avoids the need to know the true value of the quantity of interest. To form the necessary triplet datasets, ionosondes, International Reference Ionosphere (IRI), NeQuick, and the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) data are used in addition to COSMIC. To verify the feasibility of this method under the error conditions of the data used in this paper, we initially verified the method using simulated data. The error characteristics are analyzed according to local time and geomagnetic latitude. IRO electron density error characteristics are found to be primarily related to inversion assumptions. The COSMIC IRO errors are smallest in summer and largest in winter, and the errors in high solar activity years are larger than the errors in low solar activity years. When understanding error results derived from the 3CH method, special attention should be given to the impact of error correlation and representativeness errors. The results show that the 3CH method provides a better characterization of the errors in COSMIC IRO observations, is helpful for the specification of errors in data assimilation systems, and is suitable for estimating errors in geospace observations.

Precise characterization of the thermospheric neutral wind is essential for comprehending the dynamic interactions within the ionosphere-thermosphere system, as evidenced by the development of models like HWM and the need for localized data. However, numerical models often suffer from biases due to uncertainties in external forcing and the scarcity of direct wind observations. This study examines the influence of incorporating actual neutral wind profiles from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) on the Ionospheric Connection Explorer (ICON) satellite into the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM) via an ensemble-based data assimilation framework. To address the challenges of assimilating real observational data, a robust background check Quality Control (QC) scheme with dynamic thresholds based on ensemble spread was implemented. The assimilation performance was evaluated by comparing the analysis results against independent, unassimilated observations and a free-running model Control Run. The findings demonstrate a substantial improvement in the precision of the thermospheric wind field. This enhancement is reflected in a 45–50% reduction in Root Mean Square Error (RMSE) for both zonal and meridional components. For zonal winds, the system demonstrated effective bias removal and sustained forecast skill, indicating a strong model memory of the large-scale mean flow. In contrast, while the assimilation exceptionally corrected the meridional circulation by refining the spatial structures and reshaping cross-equatorial flows, the forecast skill for this component dissipated rapidly. This characteristic of “short memory” underscores the highly dynamic nature of thermospheric winds and emphasizes the need for high-frequency assimilation cycles. The system required a spin-up period of approximately 8 h to achieve statistical stability. These findings demonstrate that the assimilation of data from ICON/MIGHTI satellites not only diminishes numerical inaccuracies but also improves the representation of instantaneous thermospheric wind distributions. Providing a high-fidelity dataset is crucial for advancing the modeling and understanding of the complex interactions within the Earth’s ionosphere-thermosphere system.

Using observations from a meteor radar chain, the Aura satellite, and reanalysis data, this study investigates the characteristics of quasi‐5‐day waves (Q5DWs) in the mesosphere and lower thermosphere (MLT) region of the Northern Hemisphere during the January 2021 Arctic sudden stratospheric warming (SSW) event. After the SSW onset, westward‐propagating Q5DWs were detected in the MLT region at Mohe (53.5°N), Beijing (40.3°N), Wuhan (30.5°N), and Ledong (18.3°N). Hough function calculation and satellite observations reveal that the Q5DWs observed in meteor radar winds at Mohe and Beijing consist of both westward wavenumber 1 (W1) and westward wavenumber 2 (W2) components, whereas the W1 component dominates at Wuhan and Ledong. The key findings of this study include: (a) both meteor radar and satellite observations identified the weakest Q5DW activity at low latitudes during the SSW event, and (b) in addition to a mesospheric wave source for W1 and W2 components around 55°N, an additional mesospheric wave source for the W1 component around 35°N was identified, likely contributing to its broader latitudinal coverage compared to the W2 component. These results offer valuable insights into the latitudinal evolution of Q5DWs in the MLT region during SSW events.

Artificial intelligence (AI) weather forecasting has advanced rapidly owing to its high prediction accuracy and exceptional computational efficiency. However, research on stratospheric forecasting and multi-step prediction strategies remains relatively underdeveloped compared to studies focused on the troposphere or model architecture improvements. Stratospheric wind plays a crucial role in the flight performance of balloon experiments. Although Numerical Weather Prediction can generate forecasts by solving atmospheric partial differential equations, its expensive computational cost fundamentally limits the capability of short-term prediction. In recent years, artificial intelligence technology has been increasingly applied to atmospheric predictions. In this study, we build convolutional neural network (CNN) and long and short-term memory (LSTM) network models for single point (95.5° E, 37.5° N) and area (90–100° E, 30–40° N) predictions of the short-term zonal wind in the stratosphere. The convolution architecture is found to outperform the LSTM models. Four prediction strategies including multi-input multi-output (MIMO), DirRec, and hierarchical time aggregation (HTA) and DirRec are implemented and compared to achieve multi-step forecasting. MIMO, DirRec, and HTA strategies are found to have higher prediction accuracy than the recursive strategy, and the DirRec strategy requires significantly higher computational costs. Hence HTA and MIMO are considered more suitable in stratospheric wind pre-diction. The HTA strategy is better for forecasts in 1-6th steps, while the MIMO strategy is optimal for forecasts in 7-12th steps. The HTA performs faster in training time than multi-input multi-output, but slower inference time. Our comparison is helpful for selecting appropriate strategies for different neural network–based forecast scenarios.

The stellar occultation technique detects Earth’s atmospheric components by measuring the absorption of the stellar spectrum. In this paper, A method of air density retrieval using stellar occultation transmission data in oxygen absorption A band is studied. In this method, the average single-band transmission in oxygen A-band is used to calculate the effective optical depth of each layer of atmosphere by using the peeling onion algorithm. Then, the effective optical depth of each layer and prior atmospheric temperature data are used to obtain the oxygen number density profile by using the retrieval method. Finally, the stable proportion of oxygen in the atmosphere is taken into account. By introducing the iterative algorithm of atmospheric static equilibrium and ideal gas state equation, the accuracy of air density retrieval is improved under the condition of deviation of prior temperature. The results of simulation retrieval are presented in this paper. This method overcomes the negative influence of prior temperature deviation on the retrieval accuracy, and provides a new method and theoretical basis for stellar occultation detection and air density detection.

The determination of the wave turbopause is vital for understanding the dynamics of atmospheric processes in the Mesosphere and Lower Thermosphere (MLT). In this study, we introduce a novel approach for identifying the wave turbopause, using SABER/TIMED temperature data and number density data, addressing the limitations associated with traditional linear fitting methods that can lead to ambiguities in results. Our approach is grounded in the conservation-of-energy principle, which facilitates the introduction of an energy index to effectively delineate the boundaries of the turbopause layer. This method allows us to define several key parameters: the lower boundary height, upper boundary height, turbopause height, and turbopause layer thickness. Analyzing long-term SABER data specifically over Beijing, we observed that the turbopause layer exhibited significant seasonal and inter-annual variations. Our findings indicated that the average height of the lower boundary was approximately 69.17 km, while the average height of the upper boundary was around 93.85 km. The energy index provided a comprehensive assessment of atmospheric wave activity, revealing periodic variations at different altitudes within the turbopause layer. The proposed method not only offers a more precise and applicable characterization of the turbopause but also enhances our capacity for atmospheric modeling and empirical investigations. Future work will focus on extending this methodology, to analyze the comprehensive SABER data collected globally. We aim to uncover insights into the seasonal characteristics of the turbopause across various geographic regions, allowing for a more detailed understanding of its behavior under different climatic conditions, ultimately contributing to a deeper understanding of MLT dynamics.

Abstract. Horizontal wind observational data by the dual-frequency Stratosphere-Troposphere-Meteor (ST-M) radar at Langfang Observatory from March 2023 to February 2024, was used to investigate spatiotemporal variations, and propagation characteristics of planetary waves, as well as the relationship between planetary waves in the troposphere and stratosphere (ST) and the mesosphere and lower thermosphere (MLT) over Langfang mid-latitude regions. The quasi-16-day planetary wave’s activities are obtained by applying band-pass filtering on the daily averaged horizontal wind. Simultaneous MERRA-2 reanalysis wind data are used to derive the dominant zonal wavenumbers of 16-day waves in ST and mesosphere, and also the background zonal winds through which the planetary may propagate vertically. Results show that 16-day wave activity occurs all the year, its zonal component is stronger than the meridional component, and it is characterized by being strong in winter and weak in summer. It is newly found that the vertical phase propagation direction of 16-day wave got changed during autumn and winter that in autumn August–September it is upward in ST and downward in MLT, and upward in ST but upward in MLT in November–December, and downward in ST and upward in MLT after later December. The dominant zonal wavenumbers for the 16-day wave are (ST: -1, MLT: 2) in August–September, and (ST: 2, MLT: 4) in November–December, and (ST: -1, MLT: 4) in December–January respectively in MERRA-2 data. It can be derived with the information of vertical phase velocity and zonal wavenumber that the group velocity of the 16-days in radar data is downward in ST and downward in MLT in August–September, and upward in ST and upward in MLT in November–December, and downward in ST and Upward in MLT in December–January, respectively. Together with the zonal background winds from MERRA-2 and radar over the field site which provide the vertical propagation condition for planetary waves, it can infer that the observed 16-day wave in ST may be triggered by the jet at about 14km altitude and hence propagated downward in August–September, and the background wind do not allow upward propagating of the wave. So, the observed wave in MLT in August–September may be trigged by another unknown source above or refracted from low-or-high latitude regions. The observed 16-day wave in ST in November–December is not the same as that before, was generated in the lower atmosphere and propagated through the background winds upward maybe into the MLT regions as observed. In December–January, the observed 16-day wave in ST gets changed zonal wavenumber again, it is also generated in the lower atmosphere and propagate upward. However, its upward propagation will be blocked by the above winds and therefore cannot penetrate into the MLT above. The observed wave in MLT in December–January could be the one already existed there before. The newly observations and interpretations help us to further understanding the vertical coupling among the ST and MLT by planetary waves.

Sudden stratospheric warmings (SSWs) are dramatic events in the polar winter stratosphere that are accompanied by atmospheric parameter anomalies in the stratosphere and mesosphere. Microwave Limb Sounder and Global Navigation Satellite System Occultation Sounder observations on board the Chinese FengYun 3 satellites indicate a rapid increase of over 50 % in the mesospheric density at high latitudes around the onset date during the 2021 major SSW event. The amplification of the zonal mean density around the onset is proportional to the latitude increase with a maximum increment of 83.3 % at 59 km above 80° N, which is more than 3 times larger than the climatological standard deviation (23.1 %). The horizontal density distributions are influenced by the changing polar vortex fields. A simulation using a specified dynamics version of the Whole Atmosphere Community Climate Model reproduces the global circulation and presents a severe change in the planetary wave forcing and residual meridional circulation mass flux followed by a change in the density tendency. These results demonstrate that the observed enhanced density is primarily attributed to the altered planetary waves and residual circulation during the SSW event. The observations and simulations also indicate that the density anomalies could extend to middle latitudes. Obvious density disturbances in the upper stratosphere and mesosphere were observed by the lidar deployed in Beijing (40.3° N, 116.2° E).

The ICON satellite provides new data for environmental characterization,modeling,and forecasting in near space.In this paper,the ICON/MIGHTI and TIMED/SABER temperature datasets were compared and analyzed in the range of 90～105 km,and the mean temperature deviation and root-mean-square error of both were calculated.The distribution of monthly mean temperature deviation with altitude and latitude in different months was also analyzed,which is useful for applying the MIGHTI and SABER temperature data in the model and forecast.The results showed that the MIGHTI and SABER vertical profile detections agreed.In the range of 12°S-42°N,the MIGHTI probe temperature is lower than that of SABER in the range of 90～93 km,with a maximum deviation of about 2.5 K,and higher in the range of 93～105 km,with a maximum absolute value of the deviation of about 10 K.The deviation was usually higher during the day than at night.The mean temperature deviation varied sig-nificantly with season and latitude and had the largest mean deviation range and the largest root-mean-square temperature error in summer.

Geomagnetic storms can cause large variations in the ionosphere, but their impacts on the mesosphere and lower thermosphere (MLT) are not well understood. Based on the Total Electron Content (TEC) data and the meteor neutral winds data over Mohe (53.5°N, 122.3°E) and Beijing (40.3°N, 116.2°E), we analyze the tidal variations during six intense geomagnetic storms from 2016 to 2021. According to the six intense geomagnetic storms, we found that intense geomagnetic storms can lead to diurnal and semidiurnal tidal enhancements in TEC, while their influences on tidal variations in the MLT region are not always captured. Responses of tidal enhancement in the MLT region to the intense geomagnetic storms are more obvious at a lower latitude at Beijing, but the tidal amplitude changes are not proportional to the Dst indices. Some semidiurnal tides are significantly enhanced prior to the onset of geomagnetic storms, which needs to be statistically investigated in the future based on additional observations.

High precision inter-satellite velocity measurement technology is one of the key technologies for realizing integration of satellite laser communication measurements and autonomous navigation.We propose an inter-satellite coherent optical communication link velocity measurement method based on modulated code element Doppler measurement.The method adopts a one-way unidirectional approach to obtain phase-continuous code element Doppler signals by using the phase and symbol information of code element symbol synchronization and verdict at the receiver side and by removing the phase modulation information in the baseband sampling data.This can aid in realizing the real-time high accuracy of satellite relative motion velocity while completing inter-satellite communication.The simulation results verify that this method can achieve the relative velocity measurement from 0 to 11.625 km/s at a communication rate of 1 Gbit/s and bit error rate(BER)of 10-9.Furthermore,the velocity measurement uncertainty exceeds 10.00 mm/s.

The satellite ozone data of ENVISAT-1/GOMOS(Global Ozone Monitoring by Occulta-tion of Stars)and TIMED/SABER(Sounding of the Atmosphere using Broadband Emission Radiome-try)are analyzed to provide a statistical analysis of the distribution of ozone in the tropical mesosphere(60～110 km)at night(20:00 LT-24:00 LT)and explore its correlation with the 27-day solar cycle with HAMMONIA(Hamburg model of the neutral and ionized atmosphere).Both observations and model in-dicate that the nighttime ozone in the mesosphere peaks at 95 km and there is a semiannual oscillation in the upper mesosphere;Comparison with Lyman-α solar radiative forcing data over the same period shows that upper mesospheric(above 80 km)ozone may be inversely correlated with solar forcing,and lower mesospheric ozone may be positively correlated with solar forcing..In order to better explore the correlation with solar activity,the ozone data were processed by filtering,and it was found that the in-verse correlation between ozone at 95 km and Lyman-α was more significant.This correlation is more pronounced when long-term and short-term fluctuations are removed,especially in the months before and after the period of maximum amplitude of the 27-day solar radiative forcing cycle(around January and July 2004).Although the observations and the model results share some common features in the temporal and spatial distribution of ozone variations with months,large differences are found in the val-ues of the peaks where the amplitude of ozone sensitivity is greatly underestimated by the model.

Atmospheric gravity waves are one of the important dynamic processes in near space and are widely present in the atmosphere. They play a crucial role in the transfer of energy and momentum between different regions of the atmosphere. The Sun, as the ultimate source of gravity wave energy, significantly influences the intensity of gravity wave disturbances through its activity variations. This paper utilizes data from the Global Navigation Satellite System Occultation Sounder (GNOS) onboard the Fengyun-3C (FY-3C) satellite to invert global stratospheric gravity wave disturbances. It provides the global stratospheric gravity wave distribution from 2015 to 2023, nearly covering one solar activity cycle, and focuses on analyzing the response of gravity waves at different latitudes, altitudes, and wavelengths to the solar activity cycle. We found that short-wavelength gravity waves respond more noticeably to solar activity compared to long-wavelength gravity waves. Through analyzing the intensity of stratospheric gravity wave disturbances across different latitude bands, we found that in high-latitude regions, stratospheric gravity wave disturbances are most sensitive and respond most quickly to variations in solar activity. Furthermore, the Southern Hemisphere exhibits a stronger response to the current year’s solar activity changes compared to the Northern Hemisphere. In the mid-latitude and equatorial regions, the response to changes in solar activity intensity is delayed. The correlation gradually strengthens with this lag, reaching a very strong level after a 2-year lag. Additionally, the correlation between the Southern Hemisphere and solar activity is generally higher than that of the Northern Hemisphere.

A new dual-frequency, dual-mode reconfigurable digital receiver based on Field-Programmable Gate Array (FPGA) dynamic reconfiguration is proposed, which is based on a common hardware platform of high-bandwidth RF front-end, high-speed data acquisition, and real-time signal processing. The receiver adopts the design of dynamically reconfigurable down-conversion, filter extraction, and matched filtering in the digital domain. In this study, we completed the design and development of the digital receiver, experimental platform construction, and field detection test with hardware and software cooperation. The experimental results show that the receiver achieves full digital reception and signal processing for 53.8 MHz stratosphere–troposphere (ST) detection and 35.0 MHz meteor detection and successfully acquired the number of meteors versus time, the meteor trail, and low-altitude atmospheric radial winds. This dual-frequency, dual-mode reconfigurable digital receiver can be applied to new-generation multifunction integrated radar systems such as dual-frequency ST/meteor radars.

AbstractThis study compares the ozone valleys over the Tibetan Plateau (TP) and the Rocky Mountains (RM) using the ERA5 reanalysis data set. The dynamical transport of the ozone over these two regions is analyzed using the Lorenz circulation decomposition method. The ozone content valley over TP is observed around 200–50 hPa (upper troposphere and lower stratosphere, or UTLS), and that over RM is around 300–100 hPa. It is shown that the TP ozone content is smaller than that over RM. By analyzing the spatiotemporal distribution of the ozone content and the general circulation, the anticyclone over Southern Asian (SAH) plays a significant role in existence of the TP ozone valley, and the ozone content flux reaches its maximum in July. Large‐scale terrain and related general circulation determine the ozone valley appearance. Further analysis suggests that stationary transport has a larger impact on the ozone valley formation than the transient transport. The transport by the zonal circulation nearly cancels out most of that by the meridional circulation, due to the fact that the zonal transport magnitude is nearly equal to the meridional transport. The transport center over the RM is much weaker than that over the TP. Furthermore, the contrasts between transient and stationary transports are less evident over RM than over TP. The eddy‐driven stationary ozone transport flux significantly impacts the development of the two low ozone centers across these large terrains.

The stellar occultation technique is capable of atmospheric trace gas detection using the molecule absorption characteristics of the stellar spectra. In this paper, the non-iterative and iterative retrieval methods for oxygen and air density detection by stellar occultation are investigated. For the single-band average transmission data in the oxygen 761 nm A-band, an onion-peeling algorithm is used to calculate the effective optical depth of each atmospheric layer, and then the optical depth is used to retrieve the oxygen number density. The iteration method introduces atmospheric hydrostatic equilibrium and the ideal gas equation of state, and it achieves a more accurate retrieval of the air density under the condition of a priori temperature deviation. Finally, this paper analyzes the double solution problem in the iteration process and the ideas to improve the problem. This paper provides a theoretical basis for the development of a new type of atmospheric density detection method.

The sudden stratospheric warming (SSW) is dramatic event in the winter stratosphere, during which the stratospheric temperature rapidly increases and the zonal winds reverse over the Poles. The variation of the neutral air density in the middle atmosphere during the 2021 major SSW event is investigated, using the observations from Microwave Limb Sounder (MLS), the Global Navigation Satellite System (GNSS) Occultation Sounder (GNOS) on board the Chinese FengYun 3 (FY-3) and lidar deployed in Beijing (40.3° N, 116.2° E). A rapid increase of over 50% is observed by the satellites in the mesospheric density at high latitudes around the onset date and obvious density disturbances in the upper stratosphere and mesosphere were observed by lidar deployed in Beijing (40.3° N, 116.2° E). The amplification of the zonal mean density around the onset is proportional to the latitude increase with a maximum increment above 80° N, which is more than three times larger than the climatological standard deviation. The horizontal density distributions are influenced by the changing polar vortex fields. A simulation using a specified dynamics version of the Whole Atmosphere Community Climate Model is consistent overall with the observations and presents a severe change in the planetary wave forcing and residual meridional circulation mass flux followed by a change in the density tendency. These results demonstrate that the observed enhanced density is primarily attributed to the altered planetary waves and residual circulation during the SSW event. The observations and simulations also indicate that the density anomalies could extend to middle latitudes and lead the density disturbances over Beijing.

In this paper, we investigate the activity of atmospheric turbulence in the MLT region and the relationship between the activity of atmospheric turbulence and atmospheric wave activity. We use data from the Langfang MF radar (39.4∘N, 116.7∘E) from July 2019 to June 2020 and NRLMSIS 2.0 to calculate the parameters of atmospheric wave activity and atmospheric turbulence energy dissipation rate (ε). Atmospheric ε is modulated by different periods at different altitudes, and while there are 12 h and 24 h periods at all altitudes, the main period is different at different altitudes. A comparison of the ε with atmospheric tide activity shows that tides have an effect on ε, and the influence of tides on ε may be different at different altitudes. The pattern of variation in ε is similar to that of the atmospheric activity of the gravity wave, with both ε and the atmospheric activity of the gravity wave showing significant semi-annual variation.

大气经验模型是简单、快速获取临近空间大气数据的重要工具,对临近空间飞行器技术的研究和应用都有重要意义.综述了国内外典型临近空间大气经验模型的研究现状,包括美国标准大气、COSPAR参考大气系列模型、质谱仪非相干散射雷达系列模型、水平风场模型、全球参考大气模型和中国参考大气模型等,并对模型的发展历程和特点进行了总结,分析了国内外模型发展的差距.利用TIMED/SABER卫星观测数据统计获得的多年月均值,分别对常用的临近空间大气经验模型(USSA-76、CIRA-1986、MSIS2.0、GRAM-95 和GJB 5601-2006)在中国区域的适用性进行了定量评估.结果表明,模型在中国区域的适用性从高到底依次为:MSIS2.0、GJB5601-2006、GRAM-95、CIRA-86和USSA-76,所得结论为我国临近空间大气经验模型的建模、优化、选择和使用提供了参考.