Satellite Radio Navigation Systems Research Articles

Radio frequency interference from radio navigation satellite systems: simulations and comparison to MeerKAT single-dish data

Abstract Radio Frequency Interference (RFI) is emitted from various sources, terrestrial or orbital, and creates a nuisance for ground-based 21-cm experiments. In particular, single-dish observations will be highly susceptible to RFI due to their wide primary beam and sensitivity. This work aimed to simulate the contamination effects from the Radio Navigational Satellite System (RNSS) within the 1100-1350 (MHz) frequency band. The simulation can be divided into two parts: i) satellite positioning, emission power, and the beam response on the telescope, and ii) calibration of the satellite signals to data to improve the original model. We utilise previously observed single-dish L-band data from the Meer-Karoo Array Telescope (MeerKAT), which requires special calibration to account for regions contaminated by satellite-based RFI. We find that we can recreate the satellite contamination with high accuracy around its peak frequencies provided the satellite is not too close to the telescope’s pointing direction. The simulation can predict satellite movements and signals for past and future observations, aiding in RFI avoidance and testing novel cleaning methods. The predicted signal sits below the noise in the target cosmology window in the L-band (970 - 1015 MHz) making it difficult to confirm any out-of-band emission from satellites. However, in our simulations, this contamination still overwhelmed the 21-cm auto-power spectrum. Nevertheless it is possible to detect the signal in cross-correlations after mild foreground cleaning. Whether such out of band contamination does exist will require further characterisation of the satellite signals far away from their peak frequencies.

YOLO-RWY: A Novel Runway Detection Model for Vision-Based Autonomous Landing of Fixed-Wing Unmanned Aerial Vehicles

In scenarios where global navigation satellite systems (GNSSs) and radio navigation systems are denied, vision-based autonomous landing (VAL) for fixed-wing unmanned aerial vehicles (UAVs) becomes essential. Accurate and real-time runway detection in VAL is vital for providing precise positional and orientational guidance. However, existing research faces significant challenges, including insufficient accuracy, inadequate real-time performance, poor robustness, and high susceptibility to disturbances. To address these challenges, this paper introduces a novel single-stage, anchor-free, and decoupled vision-based runway detection framework, referred to as YOLO-RWY. First, an enhanced data augmentation (EDA) module is incorporated to perform various augmentations, enriching image diversity, and introducing perturbations that improve generalization and safety. Second, a large separable kernel attention (LSKA) module is integrated into the backbone structure to provide a lightweight attention mechanism with a broad receptive field, enhancing feature representation. Third, the neck structure is reorganized as a bidirectional feature pyramid network (BiFPN) module with skip connections and attention allocation, enabling efficient multi-scale and across-stage feature fusion. Finally, the regression loss and task-aligned learning (TAL) assigner are optimized using efficient intersection over union (EIoU) to improve localization evaluation, resulting in faster and more accurate convergence. Comprehensive experiments demonstrate that YOLO-RWY achieves AP50:95 scores of 0.760, 0.611, and 0.413 on synthetic, real nominal, and real edge test sets of the landing approach runway detection (LARD) dataset, respectively. Deployment experiments on an edge device show that YOLO-RWY achieves an inference speed of 154.4 FPS under FP32 quantization with an image size of 640. The results indicate that the proposed YOLO-RWY model possesses strong generalization and real-time capabilities, enabling accurate runway detection in complex and challenging visual environments, and providing support for the onboard VAL systems of fixed-wing UAVs.

Compact antenna device for receiving glonas signals in frequency ranges L1 and L2

Problem statement. The article presents the material on the development of compact antenna devices designed to receive GLONASS signals in the frequency ranges L1 and L2. The basic requirements for the design and characteristics of compact antenna devices designed to receive GLONASS signals are described. Aspects of the fundamentals of the design of a compact 25x25x7.5 mm dual-frequency three-layer patch antenna, where the third layer (bottom board) is a power amplifier, which has not been used before, are discussed. Simulation results of the developed compact antenna device are presented and recommendations for the power amplifier are given. Objective. To develop a compact dual-frequency patch antenna with circular polarization, providing a high level of reception of GLONASS signals in the frequency bands L1 and L2, which includes a power amplifier. Results. On the basis of methods of electrodynamic modeling, computational methods of technical electrodynamics, methods of full-scale experimental measurements of antenna characteristics and methods of computer processing of data of full-scale experimental measurements, a compact antenna device with circular polarization is developed, providing reception of GLONASS signals in frequency ranges L1 and L2. The developed compact antenna device is made on the basis of a three-layer patch antenna, having one common point of voltage supply and located in a dielectric case on a metal base, where each layer is a printed circuit board. The upper printed circuit board provides reception of GLONASS signals in frequency ranges L2, the middle board provides reception of GLONASS signals in frequency ranges L1, the lower board - power amplifier significantly increases the gain in radiation of the compact antenna device. The use of this development for the reception of GLONASS signals in the frequency ranges L1 and L2, including as part of the antenna array, will provide significantly more space for placement of payloads, due to its small mass and dimensions. Practical significance consists in providing a high level of reception of signals of the network radio navigation satellite system GLONASS in frequency ranges L1 and L2, designed for global operational navigation of ground mobile objects. The developed compact antenna device with circular polarization and antenna arrays based on it can be used for electronic warfare and can also be used for civilian purposes.

A Software Tool for the True Height Analysis of Ionograms Using the Iterative Gradient Correction (IGC) Method

AbstractDeriving the precise true height electron density profile from the measured ionosonde virtual heights is quite a challenging problem. Recently, Ankita and Tulasi Ram (2023, https://doi.org/10.1029/2023RS007808) presented a new method, Iterative Gradient Correction (IGC) method, for true height analysis that uses HF radio wave propagation path computations to reconstruct the true height profile. Through iterative corrections on electron density gradients between successive points, the IGC method minimizes errors below a specified tolerance at each point and reconstructs a complete electron density profile. The derived profiles from the IGC method are found to be accurate when compared with Incoherent Scatter Radar and Global Navigation Satellite System—Radio Occultation observations. To facilitate true height analysis by IGC method for a wider user community, a MATLAB‐based software has been developed and is outlined in this report. The software can be installed on any Windows platform and is designed with a user‐friendly interface for easy and efficient application by the users. It can analyze multiple scaled ionograms in a single run and outputs the real height profiles in ASCII format. Further, the software also captures important ionospheric parameters such as the base altitudes and peak frequencies of E‐ and F‐layers (e.g., hE, hF, foE, and foF2) etc., from the computed true height profiles and tabulates in a separate output file for the ready use. The software also provides the option for extrapolation of true height profile into top‐side ionosphere up to a user‐specified height and reconstructs the complete vertical electron density profile.

System for delivering radio interference transmitters to receiving devices of ground-based radio electronic means of satellite radio communication and radio navigation systems

Formulation of the problem. The method of delivering radio jamming transmitters to the area where a radio-electronic device is located, based on dropping transmitters from an unmanned aerial vehicle, is characterized by a number of disadvantages: high complexity of the equipment and, accordingly, the high cost of the UAV; low efficiency of radio interference transmitters in suppressing ground-based radio electronics of satellite radio communication and radio navigation systems. Purpose. Consider the possibility of increasing the efficiency of radio-electronic suppression of ground-based radio electronics of satellite radio communication and radio navigation systems by autonomous radio jamming transmitters delivered to the work area using UAVs, while reducing the complexity of the equipment and the cost of UAVs - carriers of radio jamming transmitters. Results. A delivery system for radio interference transmitters is proposed. The system uses an uncontrolled free aerostat (balloon) filled with gas as a UAV. The volume of gas depends on the given flight altitude. The balloon, together with the transmitter and battery, is launched from a starting position placed on the earth's surface, taking into account the known direction of the wind and the known location of the suppressed weapon. The balloon is delivered to the electronic jamming work zone by moving air masses. The calculations showed that the use of the proposed system provides a gain in the required transmitter EIRP of at least 7 dB compared to a ground-based transmitter. To suppress a Starlink user terminal at a range of up to 4 km, a transmitter with an EIRP of no more than 13 dBW (20 W) is required. Practical significance. The results obtained can be used to increase the efficiency of electronic jamming of ground-based satellite radio communication and radio navigation systems.

Assessment of satellite images terrestrial surface temperature and WVP using GNSS radio occultation data

Abstract Land Surface Temperature (LST) and Water Vapor Pressure (WVP) contour maps can be produced using cameras aboard satellites, for instance, under the name “Remote Sensing (RS)”. Satellite image observations should be verified before using based on a reliable data. Global Navigation Satellite System Radio Occultation (GNSS-RO) method is observing accurate Earth atmosphere parameters continuously. In the present research, LST and WVP differences between Landsat 8 (LC08), Sentinel-3 (S3), and MODIS (Terra and Aqua) images and GNSS-RO are assessed in Egypt depending on the satellites operating periods and data availability during the years from 2015 to 2020. Statistically, S3 and Terra have insignificant differences with RO temperature with an average bias of 3.48 °C and 1.47 °C, respectively, but LC08 and Aqua have significant differences with it. For WVP, Aqua and LC08 have insignificant differences with an average bias of 0.02 kg/m2 and 2.31 kg/m2, respectively, but S3 and Terra have significant differences with RO observations. When comparing LC08 LST data to other satellites, it was found that there were insignificant differences between LC08 and S3 as well as Terra. However, significant differences were observed when comparing LC08 LST data to Aqua. Additionally, significant differences were noted when comparing LC08 WVP data to other satellites. In response to these differences, improvement models have been developed to enhance the estimation of terrestrial data through remote sensing, particularly for satellites that exhibited significant disparities when compared to reference observations (RO).

Structure and variations of global planetary boundary layer top from 2008-2022 multiple GNSS RO observations

The structural changes at the planetary boundary layer (PBL) top are very complex and closely related to climate and environmental changes. With the development of Global Navigation Satellite System Radio Occultation (GNSS RO), it provides a good opportunity to estimate and study PBL variations. In this paper, long-term variations and structures of planetary boundary layer height (PBLH) from 2008 to 2022 are investigated by the Wavelet Covariance Transform (WCT) method based on refractivity profiles from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and Korea Multi-purpose Satellite-5 (KOMPSAT-5). Furthermore, the temperature and pressure of PBL top are detected using the temperature and pressure profiles from COSMIC and KOMPSAT-5 occultation data. The results demonstrate the latitudinal distribution of the PBL top height, temperature, and pressure, with the more apparent temperature's latitudinal characteristics. The pressure is more strongly correlated with PBL height than temperature. The PBL height in most land and oceans is high in summer and low in winter, and the PBL pressure is low in summer and high in winter, according to seasonal variation characteristics. The global PBL temperature is high in summer and low in winter, which is more obvious in high latitude region. A positive correlation between latitude and the magnitude of seasonal variation in PBL temperature is observed worldwide. Seasonal variation is less pronounced in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH) due to sea-land differences. The annual average value of the global PBL height, temperature, and pressure do not change significantly over the long term, and also there is no a discernible upward or downward trend.

On the Kalman Smoother Interpolation Error Distribution in Collocation Comparison of Atmospheric Profiles

The intercomparison between different atmospheric monitoring systems is key for instrument calibration and validation. Common cases involve satellites, radiosonde and atmospheric model outputs. Since instruments and/or measures are not perfectly collocated, miss-collocation uncertainty must be considered in related intercomparison uncertainty budgets. This paper is motivated by the comparison of GNSS-RO, the Global Navigation Satellite System Radio Occultation, with ERA5, the version 5 Reanalysis of the European Centre for Medium-range Weather Forecasts. We consider temperature interpolation observed at GNSS-RO pressure levels to the ERA5 levels. We assess the interpolation uncertainty using as ‘truth’ high-resolution reference data obtained by GRUAN, the Reference Upper-Air Network of the Global Climate Observing System. In this paper, we propose a mathematical representation of the interpolation problem based on the well-known State-space model and the related Kalman filter and smoother. We show that it performs the same (sometimes better) than linear interpolation and, in addition, provides an estimate of the interpolation uncertainty. Moreover, with both techniques, the interpolation error is not Gaussian distributed, and a scaled Student’s t distribution with about 4.3 degrees of freedom is an appropriate approximation for various altitudes, latitudes, seasons and times of day. With our data, interpolation uncertainty results larger at the equator, the Mean Absolute Error being MAE≅0.32 K, and smaller at a high latitude, MAE≅0.21 K at −80° latitude. At lower altitudes, it is close to the measurement uncertainty, with MAE<0.2 K below the tropopause. Around 300 hPa, it starts increasing and reaches about 0.8 K above 100 hPa, except at the equator, where we observed MAE about 1 K.

Геоінформаційні системи для створення геодезичної основи і побудови генеральних планів населених пунктів

The use of geoinformation systems in conducting geodetic activity is a modern method of geodetic production. The development of a master plan for the territory of a settlement begins with the implementation of geodetic measurement works and the construction of a geodetic cartographic base. Geodetic measuring works are now carried out with modern geodetic devices that provide high accuracy of results, which meets the modern requirements of conducting geodetic activities in our country. With the help of modern software, they process the results of geodetic measurements and further build cartographic material. The application of Remote Sensing of the Earth data makes it possible to spatially link to terrain contours and determine the scope of geodetic measurement works for the further development of general plans of settlements. Modern requirements for the development of urban planning and land management documentation require the use of the latest devices and technologies. The use of high-precision electronic tacheometers and satellite radio navigation systems makes it possible to perform geodetic measurement work quickly and qualitatively in compliance with modern requirements for them. The use of GIS technologies, remote sensing of the Earth and modern programming makes it possible to create cartographic products in digital and paper form. The main purpose of using GIS technologies and DZZ data is to quickly identify the territory of the geodetic survey, find the points of the State Geodetic Network according to the data of the geoportal of Ukraine as a GIS technology system for linking to the starting points and obtaining initial information about them. The use of information layers of the Public Cadastral Map can help to find the source information about the territories of geodetic measurements as quickly as po The use of geodetic software enables the processing of the results of geodetic measurements and the construction of maps, plans, schemes and other cartographic products in symbols of the appropriate scale quickly and accurately. The construction of such cartographic materials serves as a geodetic basis for the development of general plans for the settlement. Our study was the territory of the village of Ivano-Shychyne, Bogodukhiv district, Kharkiv region, which belongs to the forest-steppe zone of Ukraine. To develop a master plan for the village of Ivano-Shychyne with complex relief conditions and the development of degradation processes of the soil cover had to perform a geodetic cartographic basis in digital form. And only after that, develop a master plan, since the old cartographic materials have long since lost their weight. The whole situation has changed a long time ago, new building blocks have appeared, the street and road network has developed. To compare the situation, we used the data of the DZZ, where we found significant changes, which were reflected on the constructed cartographic materials, which simplifies the solution to the problem.

The accuracy of determining the coordinates of an unmanned aerial vehicle with a navigation complex integrating an electro-optical positioning system

The article proposes the approaches to updating a strapdown inertial navigation system (SINS) based on data of the airborne electro-optical system (EOS) of an unmanned aerial vehicle (UAV). It is specified that the EOS is presented as a navigation data sensor. The rationale for the feasibility of such an approach is formed, especially in the terms of signal lack or suppression of satellite radio-navigation systems. It is proposed to ensure the accuracy of self-contained navigation by assigning an UAV route, including waypoints with terrestrial references (TRs). Notably, TR-associated image information is preliminarily downloaded into the flight management computer (FMC). The automated TR identification system with denoted coordinates at next waypoints, using airborne data, in fact, allows for alternative global positioning. The reliable operation of such an integrated navigation system over sufficiently extended legs of flight path, first, depends on the accuracy of its constituent elements. Taking into consideration the fact that conventional sensors of navigation information, such as a SINS and an altimeter, are quite well studied in numerous contributions. The article focuses on the UAV airborne electro-optical system and, specifically, on its application features as a navigation sensor. The factors influencing the accuracy of the UAV positioning data determination at waypoints according to the data of the airborne EOS are considered. The developed mathematical model of errors for the UAV inertial optical navigation complex (IONC) is presented. The analysis of the impact of airborne altimeter inaccuracies, earth’s surface features and the shift of the onboard digital camera optical axis, caused by random evolutions of the carrier body in turbulent atmosphere on the positioning accuracy, was conducted. The results of calculating lapses in determining the UAV positioning data, equipped with IONC, are given.

Identification of Anomalous Measurements of Radio Signals by a Satellite Radio Navigation System by the Method of Statistical Processing of Measurement Discharges

Identification of Anomalous Measurements of Radio Signals by a Satellite Radio Navigation System by the Method of Statistical Processing of Measurement Discharges

Модель влияния ошибок эфемерид на точность навигационного изменения координат робототехнических комплексов

Purpose. The purpose of the study is to quantify the effect of ephemeris errors on the accuracy of the navigation determination of coordinates of robotic systems involved in the performance of special works by units of EMERCOM, using a specially developed mathematical model and a computer program for its implementation. Limitations in the development of the model are formulated. Its block diagram is presented with purpose description and calculation algorithms performed in each of the functional blocks included in its structure. Methods. Research methods are based on the theory of information support for the dynamic objects control using satellite radio navigation systems. Findings. The results of the study show the following. 1. If the ephemeris errors are the same for all navigation spacecrafts that form a “constellation” during navigation measurements of robotic system coordinates, then without taking measures to allow for the errors, the calculated robotic system location point will be determined by parallel transfer of the original coordinate system from the starting point to a distance equal to the value of this error. This conclusion is confirmed by the calculation results. 2. If the ephemeris errors for all navigation spacecrafts that form a “constellation” during navigation measurements of robotic system coordinates are different, the calculated robotic system location point will also differ from its true position in different ways. 3. The calculations show that at various points of the robotic system location, the deviation of the calculated trajectory from its true one in absolute value approaches the absolute ephemeris error. This result indicates that a priori known ephemeris errors can be used to judge the error they introduce into the navigation determination of robotic system coordinates if the ephemeris errors are not compensated or algorithmically excluded from the results of navigation measurements. For other unmanned aerial vehicle (UAV) trajectories, the effect of ephemeris errors on the accuracy of their navigation measurement can be estimated using this program. Research application field. In practice, the results of the study can be used when planning special work carried out by fire and rescue units of EMERCOM of Russia. Conclusions. According to the initial data on the required quality of controlling robotic systems involved in special works, it will be possible to take the necessary measures in advance to consider ephemeris errors contained in transmitted navigation messages, or to neglect them if their effect on the control accuracy can be neglected.

On the development of satellite geodetic networks using mobile monitoring and control stations

The article gives an overview of the structural elements of geodetic networks of various types. For satellite geodetic networks, a promising method of using mobile monitoring and control stations is considered. This method provides an increase in the reliability and stability of the orbital constellation, however, when implementing it, it is necessary to pay special attention to the issue of geodetic referencing of the antennas of mobile monitoring and control stations. The problem of geodetic support for the phased deployment of the GLONASS satellite radio navigation system is described. It is shown that the developed methods of geodetic work on the binding of trajectory tracking stations of artificial Earth satellites provide the necessary accuracy, but can be improved in the process of experimental work.

An accurate orientation measurement system of self-propelled artillery barrel based on coordinate system mapping

Barrel orientation accuracy is an essential factor affecting the hit rate of self-propelled artillery, which comprehensively reflects the working state of the self-propelled artillery fire control system. An accurate self-propelled artillery orientation measurement system based on the coordinate system mapping is proposed to reduce the axis simulation error and introduce the north datum. The measurement system uses Radio Navigation Satellite System orientation technology to determine the measurement area’s standard north orientation. Based on the standard north orientation, a coordinate measurement system is established. The total station and self-propelled artillery positions are unified to the coordinate measurement system. The total station measures the coordinates of the marked points on the barrel. According to the coordinates of the marker points under different datums, the mapping relationship of different coordinate systems can be obtained. The total station measures the azimuth and elevation angle of the line connecting the marked points. Based on the coordinate system mapping relationship, the accurate orientation of the self-propelled artillery barrel can be calculated. The combined standard uncertainty evaluation is performed, and the uncertainties of the azimuth and elevation angles are and , respectively. A particular type of self-propelled artillery is selected for experiments. The results show that the system’s measurement accuracy can be guaranteed within .

Investigation of the Potential Saturation of Information from Global Navigation Satellite System Radio Occultation Observations with an Observing System Simulation Experiment

Abstract The potential impact of large numbers of Global Navigation Satellite System radio occultation (GNSS-RO) observations on numerical weather prediction is investigated using a global observing system simulation experiment (OSSE). The hybrid four-dimensional ensemble variational Gridpoint Statistical Interpolation (GSI) data assimilation system and Global Earth Observing System (GEOS) model are used to ingest up to 100 000 GNSS-RO soundings per day in addition to the current suite of conventional and radiance data. Analysis quality, forecast skill, and forecast sensitivity to observation impact are examined with differing quantities of additional GNSS-RO profiles. It is found that saturation of information from additional RO soundings has not been reached with 100 000 soundings per day. There are some indications of suboptimal performance of the GSI in handling GNSS-RO observations particularly in the middle- and lower-tropospheric extratropics.

ПОДДЕРЖКА ПЕТЕЛЬ СЛЕЖЕНИЯ ЗА ФАЗОЙ В ПРИЕМНИКЕ СПУТНИКОВОЙ НАВИГАЦИИ С ПОМОЩЬЮ ИЗМЕРЕНИЙ ИНЕРЦИАЛЬНОЙ НАВИГАЦИОННОЙ СИСТЕМЫ

Satellite radio navigation systems make it possible to evaluate the user's state vector, usecoordinates, user speed and time relative to the system scale. The requirements for the characteristicsof these systems constantly depend on the fact that they have application features in theiralgorithms for processing radio navigation signals. One of the main characteristics of satelliteradio navigation systems is the accuracy of estimating the user's state vector. This characteristiccan be improved by the presence of estimates of the phase of the received radio navigation signals.In a satellite radio navigation system, phase estimation errors in the tracking loop have two components:dynamic and noise. To compensate for the noise error, it is necessary to reduce theequivalent noise band of the anti-aliasing filter of the phase tracking loop. However, the minimumpossible bandwidth of the smoothing filter is limited by the presence of consumer dynamics and thequality of the reference oscillator. As a result, in the presence of consumer dynamics, the sensitivityand reliability of phase tracking deteriorates. To compensate for the dynamic error in the phasetracking loop, information from an inertial navigation system can be used. The satellite radio navigationsystem and the inertial navigation system have complementary characteristics. The use ofsupport for phase tracking loops from an inertial navigation system makes it possible to increasethe sensitivity and reliability of its operation in the presence of consumer dynamics. It is assumedthat with such an implementation, the sensitivity of the phase tracking loops will be limited only bythe instability of the reference oscillator and the error of inertial measurements. To improve thecharacteristics of accuracy, sensitivity and reliability of the coherent mode of operation of the enddevice, an algorithm was developed to support phase tracking loops with measurements from aninertial navigation system. A study of the developed algorithm was carried out on a model thatuses real measurements of satellite and inertial navigation systems as input data. The developedalgorithm is implemented in the software of the NV216C-IMU inertial satellite navigation systemprototype. Experimental studies were carried out in the conditions of automobile dynamics in openareas. The research results are presented in the work.

An improved total station measurement method for the georeferenced orientation of self-propelled artillery barrel

Self-propelled artillery is the main suppressing weapon installed by the armies of various countries, which plays an important role in modern warfare. With the continuous development of military science and technology, modern warfare has put forward higher requirements for the autonomous combat capability and precision strike capability of self-propelled artillery. Therefore, it is necessary to measure and verify the orientation of the self-propelled artillery barrel after maintenance and before firing. Among the various methods to achieve high-precision measurement of self-propelled artillery barrel orientation, the total station measurement method has shown good results in measurement accuracy, cost-effectiveness, and applicability to complex environments. However, there are some problems in the traditional total station measuring barrel orientation method, such as the lack of a north benchmark and the barrel calibration error. Therefore, this study aimed to develop an improved method for measuring the barrel orientation of self-propelled artillery, which solved the above problems by integrating the standard north orientation and the simulated axis of the barrel using a total station. First, to establish the measurement coordinate system of the measurement area, the standard north orientation of the measurement field area is determined using a positioning orientation instrument based on the Radio Navigation Satellite System. Second, to complete the barrel calibration, two magnetic target plates are set on the barrel, and a fixed spatial positional relationship between the connection line of the magnetic target center points and the barrel axis is established. Third, the barrel of self-propelled artillery is adjusted to the measurement attitude, and the magnetic target is observed and sighted with a total station to obtain its spatial coordinates in the measurement coordinate system. Subsequently, the error analysis of the measurement plan was carried out, and it was found that the position of the total station had a great influence on the measurement accuracy of the barrel orientation. Therefore, the uncertainty model of the measurement accuracy about the location of the station is established, and the station deployment area is scanned based on the idea of the Monte Carlo method to find the optimal measurement area. Finally, a certain type of self-propelled artillery is used to carry out an installation experiment. The experiment shows that the improved method solves the problems of the traditional method which lacks a north benchmark and the barrel calibration error, and can ensure that the measurement error is within 0.2mil, which assists in the development of precision self-propelled artillery strikes.

Stereo Plume Height and Motion Retrievals for the Record‐Setting Hunga Tonga‐Hunga Ha'apai Eruption of 15 January 2022

AbstractStereo methods using GOES‐17 and Himawari‐8 applied to the Hunga Tonga‐Hunga Ha'apai volcanic plume on 15 January 2022 show overshooting tops reaching 50–55 km altitude, a record in the satellite era. Plume height is important to understand dispersal and transport in the stratosphere and climate impacts. Stereo methods, using geostationary satellite pairs, offer the ability to accurately capture the evolution of plume top morphology quasi‐continuously over long periods. Manual photogrammetry estimates plume height during the most dynamic early phase of the eruption and a fully automated algorithm retrieves both plume height and advection every 10 min during a more frequently sampled and stable phase beginning 3 hr after the eruption. Stereo heights are confirmed with Global Navigation Satellite System Radio Occultation bending angles, showing that much of the plume was lofted 30–40 km into the atmosphere. Cold bubbles are observed in the stratosphere with brightness temperature of ∼173 K.

MODERN CHANGES COUNTOUR OF COASTLINE SPITS OF THE SEA OF AZOV

Problem Statement and Purpose. At present the studying of the shores and their dynamics configuration and especially the most active parts – the heads of the Azov spits, is caused by both reasons dynamic and geopolitical changes as well. A large number of spits is a characteristic feature of the shores of the Azov Sea. There are spits all over the coast of the Azov Sea. However, spits oriented deep into the Azov Sea shore line there are just on the northern sea area. The reason of intense lithodynamic processes in the coastal zone of the Azov is the high velocities of currents in the bottom layer as a result of storm winds. In the coastal zone of the sea the cycle of abrasion rate from 1 to 4 m per year (sometimes up to 15m per year) was established. Fluctuations in the level of the Azov Sea are provides by many natural factors acting simultaneously and input to abrasion processes. The largest range of fluctuations is associated with wind activity phenomena. Data & Methods. In the paper takes into account the regular field studies of the position of the coastline of the distal parts – the streamer heads using of satellite radio navigation systems – GPS receivers. The radio navigation equipment recorded the exact route along the interaction zone. The sampling was carried out in a calm period on the sea surface. The data in situ (recorded routes) were compared with retrospective data of GIS systems. Cartographic materials, various specialized sources of information and satellite images were also used for the further analysis. Results. In fact, this paper is an attempt for the first time analysis of the available retrospective, modern and satellite monitoring data for the comparing of the dynamics of the Azov spits in frame of Ukraine area. As an example the dynamics of the coast line of the spits: Biryuchiy Island, Obitochnaya, Berdyanskaya and Belosaraiskaya were done. The study of the modern state of the Ukrainian coast line in the Azov Sea, the possible degradation of the coastal part of the sea and the reasons causes of it isessential for the sustainable development of the economy, the recreational potential of the region, the social level of the population and the geopolitical situation in the event of delimitation in the Azov Sea.

Comparison of different machine learning approaches for tropospheric profiling based on COSMIC-2 data

Precise and reliable information on the tropospheric temperature and water vapor profiles play a key role in weather and climate studies. Among the sensors supporting the observations of the troposphere, one can distinguish the Global Navigation Satellite System Radio Occultation (RO) technique, which provides accurate and high-quality meteorological profiles. However, external knowledge about temperature is essential to estimate other physical atmospheric parameters. To overcome this constraint, I trained and evaluated four different machine learning models comprising Artificial Neural Network (ANN) and Random Forest regression algorithms, where no auxiliary meteorological data is needed. To develop the models, I employed 150,000 globally distributed (45°S–45°N) RO profiles between October 2019 and December 2020. Input vectors consisted of bending angle or refractivity profiles from the Formosa Satellite-7/Constellation Observing System for Meteorology, Ionosphere, and Climate-2 mission together with the month, hour, and latitude of the RO event. While temperature, pressure, and water vapor profiles derived from the modern ERA5 reanalysis and interpolated to the RO location served as the models’ targets. Evaluation on the testing data set revealed a good agreement between all model outputs and ERA5 targets, where slightly better statistics were noted for ANN and refractivity inputs. Vertically averaged root mean square error (RMSE) did not exceed 1.7 K for the temperature and reached around 1.4 hPa and 0.45 hPa for the total and water vapor pressures. Additional validation with 477 co-located radiosonde observations and the operational one-dimensional variational product showed slightly larger discrepancies with the mean RMSE of around 1.9 K, 1.9 hPa, and 0.5 hPa for the temperature, pressure, and water vapor, respectively.Graphical