Modern Satellite Research Articles

Інтелектуальні методи та моделі обробки супутникових даних у задачі моніторингу звалищ

Статтю присвячено розв’язанню важливої прикладної задачі пошуку сміттєзвалищ на основі методів машинного навчання з використанням супутникових даних високого просторового розрізнення. Проблема накопичення і зберігання відходів на легальних та несанкціонованих сміттєзвалищах актуальна і на сьогоднішній день. В Україні щороку утворюються мільйони тонн побутових відходів. Найбільші площі під полігони зайняті в Донецькій, Дніпропетровській, Одеській, Запорізькій областях. Так, в Донецькій області площі під сміттєзвалища займають 330 гектарів. Для моніторингу сміттєзвалищ використовуються різні технології, що базуються на супутникових даних і методах штучного інтелекту. Нині існують сервіси, за допомогою яких відстежується розташування сміттєзвалищ, але не надається інформація про територію сміттєзвалища та зміни її площі в часі. У процесі виконання досліджень розв’язано важливу задачу відокремлення полігонів від кар’єрів та штучних об’єктів шляхом поєднання попіксельної та об’єктної класифікації. Основна мета роботи полягала в розробці інтелектуальної інформаційної технології на основі нейромережевого підходу і побудові на її основі геопросторового продукту розміщення звалищ для Донецької області, а саме карти класифікації звалищ відходів. Запропонований алгоритм машинного навчання на основі історичних та сучасних супутникових даних дозволяє відстежувати площу полігону відходів та її зміни в часі. Розроблена інформаційна технологія апробована на території чотирьох територіальних громад у Донецькій області, а саме: Ольгинської, Мирноградської, Курахівської та Покровської. У результаті проведених досліджень також розроблено інформаційну панель, яка надає оперативні дані і дозволяє оцінювати динаміку змін сміттєзвалищ у регіоні в часі і просторі. Розроблена технологія має практичне значення для розробки програм керування та поводження з відходами в місцевих громадах.

Rapid ice sheet response to deglacial and Holocene paleoenvironmental changes in eastern Prydz Bay, East Antarctica

Prydz Bay lies at the terminus of one of East Antarctica's largest glacial systems and is a key region for understanding the response of the ice sheet to past and future environmental changes. In this study, we explore the dynamics and paleo-geometry of the ice sheet in eastern Prydz Bay, using a combination of bathymetric features on the seafloor to delineate past flow patterns, and cosmogenic nuclide dating of glacial deposits on land to constrain ice sheet terminus chronologies. Large streamlined bedforms on the sea floor record the existence of a primary ice stream in Svenner Channel, collecting ice from multiple tributary ice streams and discharging into the main trunk stream of the Lambert Glacier-Amery Ice Shelf system in Prydz Channel. The location and orientation of the north-eastern tributary to this ice stream also provide evidence for a substantial independent ice dome on the outer shelf at Four Ladies Bank. Exposure of ice-free areas at outer Rauer Group and Vestfold Hills indicates that grounding line retreat across eastern Prydz Bay was largely complete by ∼14 ka BP, and the ice margin had retreated to within ∼1 km of its present position by ∼10 ka BP. Onshore moraines record periods of ice margin retreat during the middle (∼6 ka BP) and very late (∼0.5 ka BP) Holocene coinciding with local warm periods. Subsidence recorded in modern Global Navigation Satellite System (GNSS) observations suggests the regional ice sheet was smaller than at present in the period between the middle and very late Holocene advances. The unusually dynamic ice sheet behaviour in this area is attributed to the smooth, reverse-slope bed characteristics of eastern Prydz Bay, which enabled rapid retreat of the ice sheet margin several hundred kilometres during deglacial events.

Contribution of longshore sand exchanges to mesoscale barrier-island behavior: Insights from the Virginia Barrier Islands, U.S. East Coast

The development of coastal adaptation pathways along sandy barrier-island coasts requires an understanding of multi-decadal barrier morphodynamics in response to forcings such as sea-level rise, sediment fluxes, and storminess. Long- and cross-shore sand exchanges among barrier-system compartments (shorefaces, beaches, dunes, tidal inlets, backbarrier lagoons) and between adjacent barrier islands can play a fundamental role in barrier-system morphology and resilience to sea-level rise. We explore these dynamics through investigation of historical areal changes within the 13 largely undeveloped Virginia Barrier Islands of the United States Mid-Atlantic Coast. We pair subaerial island areas mapped from historical surveys and modern aerial and satellite imagery with representative island thicknesses determined from stratigraphic and lidar-derived elevation data to estimate volumetric changes through time. Overall, the Virginia Barrier Islands lost ~3.4% (16 × 106 m3) of their 1887 C.E. volume between 1887 and 2017 C.E. The loss from three central islands (Parramore, Hog, and Cobb)—historically characterized by rotational behavior—was 43% (79 × 106 m3). In particular, Parramore Island continuously decreased in volume over the 20th and 21st centuries. In contrast, growth of Assateague and northern Wallops islands (located at the northern, updrift end of the island chain) from 1887 to 2017 C.E. resulted in a volume increase of ~59 × 106 m3. Whereas the Virginia Barrier Islands as a whole modestly decreased in size (and thus volume) directly in response to storm impacts and accelerating relative sea-level rise since the mid-1800s, the differential behavior of islands south of Assateague suggests more regional controls on coastal geomorphic behavior. Specifically, we identify the roles of antecedent substrate, sand trapping and changing wave-refraction patterns associated with the growth of Assateague Island, and inter-island sand exchanges in response to changing updrift barrier-scale behaviors. These findings help to better understand the underlying mechanisms behind state changes of barrier islands; in particular, the mechanisms by which geomorphic change along one barrier island influences those located several to tens of kilometers downdrift. This highlights the need to consider coastal beach and sand management over long reaches, even in systems which are largely unaffected by development, nourishment, and shoreline hardening.

Notes on misconceptions in the application of geographical names of the tepuis on the borderlands of Guyana and Venezuela and a clarification of the location of Waukauyengtipu and Cerro Venamo

Abstract A review of recent publications concerning the South American Pantepui biogeographic region revealed recurring mistakes in the naming of several table mountains (known locally as ‘tepui’, ‘tipu’ or ‘tepuy’) located around the Guyana-Venezuela border, close to the transection of the so-called Schomburgk Line and the course of Rio Venamo. The mistakes are believed to have arisen and have been repeated as a result of a noticeable scarcity of detailed maps of the region, its short history of exploration and ongoing inaccessibility. An extensive analysis of modern satellite data and records of past research expeditions, supplemented by first-hand observations and assessment made during an expedition to Waukauyengtipu in the Cuyuni-Mazaruni Region in Guyana in January 2019, are used to clarify the nomenclatural confusion regarding the tepuis of the area. We determine that the tepuis known as Cerro Venamo and Waukauyengtipu should be treated as separate and distinct geographic formations.

Performance Evaluation of Adaptive Tracking Techniques with Direct-State Kalman Filter.

This paper evaluates the performance of robust adaptive tracking techniques with the direct-state Kalman filter (DSKF) used in modern digital global navigation satellite system (GNSS) receivers. Under the assumption of a well-known Gaussian distributed model of the states and the measurements, the DSKF adapts its coefficients optimally to achieve the minimum mean square error (MMSE). In time-varying scenarios, the measurements’ distribution changes over time due to noise, signal dynamics, multipath, and non-line-of-sight effects. These kinds of scenarios make difficult the search for a suitable measurement and process noise model, leading to a sub-optimal solution of the DSKF. The loop-bandwidth control algorithm (LBCA) can adapt the DSKF according to the time-varying scenario and improve its performance significantly. This study introduces two methods to adapt the DSKF using the LBCA: The LBCA-based DSKF and the LBCA-based lookup table (LUT)-DSKF. The former method adapts the steady-state process noise variance based on the LBCA’s loop bandwidth update. In contrast, the latter directly relates the loop bandwidth with the steady-state Kalman gains. The presented techniques are compared with the well-known state-of-the-art carrier-to-noise density ratio ()-based DSKF. These adaptive tracking techniques are implemented in an open software interface GNSS hardware receiver. For each implementation, the receiver’s tracking performance and the system performance are evaluated in simulated scenarios with different dynamics and noise cases. Results confirm that the LBCA can be successfully applied to adapt the DSKF. The LBCA-based LUT-DSKF exhibits superior static and dynamic system performance compared to other adaptive tracking techniques using the DSKF while achieving the lowest complexity.

Assessment of land use change in the Thuma forest reserve region of Malawi, Africa

A study was conducted in Thuma area in central Malawi to quantify contemporary land cover and to explore the degree of land use change in the Thuma forest reserve area of Malawi by analysing and comparing satellite-derived land cover maps from 1997, 2007 and 2017. The study was carried out using Remote Sensing and Geographic Information System (GIS), focusing on analysis of Landsat 5 ETM and Landsat 8 ORI/TIRS satellite images. The classification was conducted for the following distinct classes; closed forest, open forest, shrubland, savanna grassland, agriculture fields, and water. The analysis revealed that closed forest diminished from 19% in 1997 to 10% in 2007 to 6% in 2017. Open forest reduced from 30% to 21% from 1997 to 2007 but increased to 22% in 2017. Agriculture area almost doubled from 37% in 1997 to 64% in 2017. The actual area from 1997 to 2017, shows that closed forest has reduced from 7,000 ha to 3,000 ha while open forest from 12,900 ha to 7800 ha. Savanna grassland has doubled from 5,900 ha to 13,000 ha. However, future studies should use modern satellites such as Sentinel and Landsat 9 for improved quantification of changes. The findings show that even the protected forest reserve (previously dominated by closed forest) is not fully protected from deforestation by local communities. Government and other stakeholders should devise measures to meet the needs of the surrounding communities and the ecological/biophysical needs of the reserves. Based on this study, issues of re-demarcation of the forest reserve and the accessed area should also be explored. This study serves as a reference for the management of Thuma Forest Reserve as a refuge for natural tree species, rivers that harbour endemic fish species (Opsaridium microlepis and Opsaridium microcephalis) and the sustainable management of endangered elephants in the reserve.

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The ability of personnel to navigate the terrain, determine azimuths to a target, landmarks or various characteristic objects, and timely arrival at a given area (line) is an important factor in achieving success in service and combat activities by subunits. However, in areas of magnetic anomalies, the use of magnetic orientation devices is difficult or not possible at all. Several types of magnetic anomalies differ depending on the size: global (mainland) ? the Carpathians, mountainous regions of Crimea, regional ? Krivoy Rog and Kremenchug and local ? accumulation of equipment, etc. The disadvantages of using a gyroscopic compass, which is a mechanical device, are the complexity of the design, large size, the need for continuous special maintenance and lack of autonomy. The article presents some alternative methods of tactful orientation on the terrain with high accuracy. Firstly, it is the use of signals from modern satellite systems. Based on these signals, software applications, including mobile ones, have been created. As a rule, these are military or �near military� applications. These are Google Earth, Maps.me, CrowdMag, Commander Compass, Topic (Topo), MyGun (UkropSoft), etc. The functionality and capabilities of these programs differ significantly from each other, but most are focused on exploring the area. Secondly, an improved method of orientation on the terrain of the �solar disk� type is proposed, which is based on the use of the position of the Sun (Moon). The proposed mobile device is lightweight and allows you to determine the true azimuth to the target or the direction of movement with an accuracy of up to 10 in the condition of magnetic anomalies. The use of this device is possible only in sunny weather, however, with average cloudiness (especially in summer), this problem is partially solved with the help of a lens and the formation of a sunspot.

ДИСТАНЦИОННОЕ ЗОНДИРОВАНИЕ ПАСТБИЩ ДЛЯ ПРОГНОЗИРОВАНИЯ ПРОДУКТИВНОСТИ ОВЕЦ

This article discusses the prospects for the use and rapid development of modern satellite systems and observation technologies in pasture farming. The main possibilities of constructing a predictive model for planning the productivity of pasture herbage on the basis of multivariate analysis of remote sensing are presented. The obtained data are used to build a technological map of animal grazing. Currently, the data obtained as a result of satellite observation and associated technologies are increasingly used in tasks related to obtaining reliable objective information about the state of agricultural land and the possibility of their industrial use. To solve the set tasks, specialized information systems and models of various levels of predicting the productivity of the land used and the productivity of pasture animals are rapidly being developed and implemented. As objectively observable data on the current state of pastures in our studies, we used multispectral images of the Copernicus Sentinel-2 Earth remote sensing satellite of the European Space Agency (ESA). The data obtained made it possible to establish the relationship between the productivity of rangelands and the vegetation index obtained by the remote method and verified by the contact method during field trials. Studies of the chemical composition and nutritional value of forage grazing plants made it possible to assess the yield of nutrients and energy from 1 m2. According to the results of accounting for the live weight of the controlled animals, it was found that the live weight of sheep grazed on pasture No. 1 statistically significantly exceeded this indicator by 6.2% in analogues that were grazed on pasture No. 2. Based on the results obtained, recommendations were made to substantiate the periods of optimal use of pasture areas, based on the use of digital methods of remote monitoring.

Использование зимних и ранневесенних космоснимков для оценки проективного покрытия березняков на залежах

More than 40 million hectares of agricultural land were abandoned after the collapse of the Soviet Union. A significant part of the land is covered by spontaneously regenerating woody and shrubby vegetation. When identifying the forest regeneration, the stands with a tree cover of more than 50% are accurately identified. It is difficult to identify the initial stages of forest regeneration on the abandoned agricultural lands using summer satellite images because of little difference between the young trees and saplings due to their low height and low density on the one hand, and herbaceous vegetation on the other. The purpose of this work was to apply winter and early-spring satellite images for assessments of the tree cover of birch-dominated stands (Betula pen-dula Roth.) formed on the abandoned agricultural lands (See Fig. 1). We used 189 releves of birch forests on the abandoned agricultural lands in the broad-leaved forest zone of the Republic of Bashkortostan. A regression analysis of the evaluation of the tree cover was carried out using the values of the spectral reflectance of the RED, NIR, SWIR11, and SWIR12 bands, as well as the values of the NDFSI snow index from seven cloudless Sentinel-2 images taken between 04.11.2020 and 13.05.2021 (See Fig. 2, 3). When selecting optimal regression models, the values of correlation coefficients (R) and determination coefficients (R2) were used to assess the model quality. To test the possibility of using the obtained models for assessing the tree cover of the stand at earlier succession stages, we involved the data on the tree cover from 36 geobotanical releves, where the crown density of the stand was visually evaluated in July 2013. Then, the described procedure was applied to calculate the tree cover using the Landsat-8 image taken on 25.03.2014. When creating regression models to calculate the tree cover, the best results were obtained using the red band of early spring images during the period when snowpack is still solid (from mid-March to the first half of April) (See Table 1). The correlation between the tree cover and the spectral reflectance of the red band was -0.90. The model allowed us to determine accurately the tree cover of birch forests aged from 18 to 20 years which prevail in the zone of broad-leaved forests in the Republic of Bashkortostan. The accuracy of the model for determining the tree cover according to the obtained regression models for other dates is unstable and highly likely influenced by the snow depth and the seasonal dynamics of changes in the radiation intensity of the red and infrared bands (See Table 2, 3). To conclude, the equations calculated from modern satellite images can be used to assess the tree cover using retrospective images at earlier succession stages of the abandoned field recovery. When using early-spring images, the snow depth should be taken into account since the snowpack melting dates can vary greatly from year to year. The paper contains 3 Figures, 3 Tables, and 41 References. The Authors declare no conflict of interest.

Methodology of geoinformation modeling of areas affected by amber mining

The article considers modern possibilities of geoinformation technologies for geospatial modeling of areas affected by amber mining in Ukraine on the example of Rivne Region. The purpose of the study is to present a methodology for decoding satellite image materials for geoinformation modeling of the areas affected by amber mining. The use of actual materials of remote sensing of modern satellite systems in combination with geospatial models during land monitoring is analyzed. It was found that the calculation of the NDVI makes it possible to identify the contours of affected areas more clearly. An approach for assessing soil cover moisture content based on the use of norm-difference water indices is presented. It is noted that the assessment of soil moisture is one of the elements of thematic processing of satellite images which makes it possible to identify the areas where amber mining by hydraulic method was carried out. It is offered to consider the method of geoinformation modeling of areas affected by amber mining as a method of practical implementation of determining affected lands using remote sensing images, due to the regularities and features of spectral analysis of a photo image. The use of the methodology is presented on a specific example, namely on state-owned lands of Dubrovytsia Forestry of Rivne Region. The methodology will provide a technical basis for the decisions on the identification of affected land plots and their further monitoring. In addition, the methodology offered in the article will help to determine the directions of land reclamation and groups of affected lands.

Development of a modern global information infrastructure based on a personal satellite communication system

The information industry is the main branch of the modern economy. The processes of informatization lead to qualitative changes in society itself in the direction of acquiring sustainable features of the modern information society, the technological basis of which is the global information infrastructure (GII). GII provides free access to information resources to every inhabitant of the planet and provides a set of communication services that provide an open set of applications, covers all types of information and provides the opportunity to receive it anywhere, anytime, at an affordable price and at an affordable price quality. The creation and operation of modern satellite communication systems contributes to the creation of a global information infrastructure. Satellite communications, which is a promising component of modern cyberspace infrastructure, is qualitatively changing the entire telecommunications industry and affecting the usual way of life. Personal satellite communication systems have significant advantages over mobile communication systems. Today, the use of new spacecraft with improved characteristics is expected, which will represent almost the entire range of satellite services. According to documents submitted to the US Federal Communications Commission, satellites in space will «communicate» with each other at a frequency of more than 10 thousand GHz using a laser beam. Ground stations and user terminals will be communicated on 12 GHz radio bands. The promised data rate is 1 Gbps for each consumer. Regarding potential Starlink applications, SpaceX’s management points to the risky nature of the low-bandwidth broadband satellite business and adds that SpaceX plans to use its Starlink satellites not only to provide broadband Internet connectivity in remote areas of the world, but also to connect on other planets.

Concise Silicon Carbide DC Circuit Breaker Module for Satellite Electrical Systems

Fault protection and real-time monitoring of Satellite Electrical Power Systems (SEPS) are of importance for the advancement of modern satellite systems of high power, compact sizing and long lifespan. Conventional protection methods could handle the overcurrent faults but lack flexibility in fault clearance time. With these important considerations, a compact and programable Silicon Carbide (SiC) power MOSFET based DC circuit breaker module is developed to not only handle multiple levels of overcurrent faults with suitable time-delay protection scheme, but also provide the real-time monitoring of circuit breaker status by using the Long Range (LoRa) and Internet of Things (IoT) Technology. The proposed module has been implemented and its effectiveness was tested and confirmed in laboratory under various overcurrent fault conditions.

КОСМОС КАК ЧАСТЬ ГЛОБАЛЬНОГО ИНФОРМАЦИОННОГО ПРОСТРАНСТВА В ПЕРИОД ВОЕННЫХ ДЕЙСТВИЙ

Purpose: To identify the current possibilities of the use of artificial earth satellites for military purposes, as well as the problems of illegal destructive use of satellites during hostilities based on analysis and systematization according to various parameters of functions of satellites as part of the modern global information space and to develop proposals that can reduce the likelihood of escalation of the conflict during the crisis. Research method: analysis of open sources on the purposeful use of modern AES, synthesis and scientific forecasting, expert assessment, factological analysis of the AES within the framework of a systematic approach. Result: the article presents an analysis and systematization significant dynamic changes at the cosmic level of the global information space associated with the large-scale spread and significant increase in the number of artificial earth satellites, as well as with the growing importance of satellites for military purposes. The article pres- ents the classification of satellites performing military functions, reveals the possibilities of modern satellites in the period of crisis and military operations and the analysis of the US satellite constellation as a leader in this field. The author poses the problems of the illegal destructive use of artificial earth satellites during military conflicts, as- sociated with this increase in the risk of cyber threats and an increase in the likelihood of escalation of the conflict, threats to Russia, international security and strategic stability. The article proves the quantitative and qualitative characteristics of the satellite constellation are today one of the most important indicators of the influence and potential of the state in the world. Scientific novelty: Proposals have been developed to minimize threats to Russia, as well as to reduce the likeli- hood of an escalation of the conflict during the crisis.

The study of large-scale variability in total water storage within the context of modern satellite gravity missions

The analysis of Earth’s gravity field changes is the one of essential task of physical geodesy. So the knowledge about selected characteristics of gravity field is the basic element of the Earth shape determining process and help to find information about mass redistribution in the Earth system. Since 2002, the gravity field changes have been successfully observed by the Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission and its continued GRACE-FO (GRACE Follow-On) mission. The results obtained from GRACE/GRACE-FO observations are presented, among other, in form of mascons and they are provid-ed by three processing centers: (1) Center for Space Research (CSR; Austin, United States), (2) Jet Propulsion Laboratory (JPL; Pasadena, United States), and (3) Goddard Space Flight Center (GSFC; Maryland, United States). In the following study, we used data provided by GSFC in form of the global distribution of Total Water Storage (TWS), which are expressed in terms of Equivalent Water Height (EWH). In our study, we focused on identifying areas with significant changes in TWS. We analysed TWS fluctuations in seasonal short-term changes, i.e., amplitude of annual oscillation (the most pronounced oscillation in the land hydro-sphere) and longterm changes, i.e., trend (a key parameter for climate studies) determined using the Least Squares Method. As a result, we selected 15 areas characterised by extreme TWS changes, i.e., 11 areas for annual amplitude and 4 areas for trend parameter. We obtained seasonal changes greater than 140 mm in areas within the equator (mainly Amazon, Niger, Ganges, Brahmaputra river basin regions) and areas covered by huge ice masses (Alaska, Greenland). The greatest rate of change in water storage at ±70 is observed around West Antarctica, Patagonia or the Caspian Sea. The results also emphasize the significant human impact in continental water masses (e.g. Mexico, Indus and Ganges river basins). Keywords: GRACE, TWS, land hydrology, gravity missions

Оценки влияния подстилающей поверхности на точность численного прогноза температуры воздуха на территории Беларуси с использованием модели WRF

The spatial structure of land use and biophysical characteristics of land surface (albedo, leaf index, and vegetation cover) are updated using the GLASS (Global Land Surface Satellite) and GLC2019 (Global Land Cover, 2019) modern satellite databases for mesoscale numerical weather prediction with the WRF model for the territory of Belarus. The series of WRF-based numerical experiments was performed to verify the influence of the updated characteristics on the forecast quality for some difficult to predict winter cases. The model was initialized by the GFS (Global Forecast System, NCEP) global numerical weather prediction model. It is shown that the use of high-resolution land use data in the WRF and the consideration of the new albedo and leaf index distribution over the territory of Belarus can reduce the root-mean-square error (RMSE) of short-range (to 48 hours) forecasts of surface air temperature by 16–33% as compared to the GFS. The RMSE of the temperature forecast for the weather stations in Belarus for a forecast lead time of 12, 24, 36, and 48 hours decreased on average by 0.40°С (19%), 0.35°С (10%), 0.68°С (23%), and 0.56°С (15%), respectively. The most significant decrease in RMSE of the numerical forecast of temperature (up to 2.1 °С) was obtained for the daytime (for a lead time of 12 and 36 hours), when positive feedbacks between albedo and temperature of the land surface are manifested most. Keywords: numerical weather prediction, WRF, digital land surface model, albedo, leaf area index, forecast model validation

Integrating Satellite, UAV, and Ground-Based Remote Sensing in Archaeology: An Exploration of Pre-Modern Land Use in Northeastern Iraq

Satellite remote sensing is well demonstrated to be a powerful tool for investigating ancient land use in Southwest Asia. However, few regional studies have systematically integrated satellite-based observations with more intensive remote sensing technologies, such as drone-deployed multispectral sensors and ground-based geophysics, to explore off-site areas. Here, we integrate remote sensing data from a variety of sources and scales including historic aerial photographs, modern satellite imagery, drone-deployed sensors, and ground-based geophysics to explore pre-modern land use along the Upper Diyala/Sirwan River in the Kurdistan Region of Iraq. Our analysis reveals an incredible diversity of land use features, including canals, qanats, trackways, and field systems, most of which likely date to the first millennium CE, and demonstrate the potential of more intensive remote sensing methods to resolve land use features. Our results align with broader trends across ancient Southwest Asia that document the most intensive land use in the first millennium BCE through the first millennium CE. Land use features dating to the earlier Bronze Age (fourth through second millennium BCE) remain elusive and will likely require other investigative approaches.

Adaptive Data Screening for Multi-Angle Polarimetric Aerosol and Ocean Color Remote Sensing Accelerated by Deep Learning

Remote sensing measurements from multi-angle polarimeters (MAPs) contain rich aerosol microphysical property information, and these sensors have been used to perform retrievals in optically complex atmosphere and ocean systems. Previous studies have concluded that, generally, five moderately separated viewing angles in each spectral band provide sufficient accuracy for aerosol property retrievals, with performance gradually saturating as angles are added above that threshold. The Hyper-Angular Rainbow Polarimeter (HARP) instruments provide high angular sampling with a total of 90–120 unique angles across four bands, a capability developed mainly for liquid cloud retrievals. In practice, not all view angles are optimal for aerosol retrievals due to impacts of clouds, sunglint, and other impediments. The many viewing angles of HARP can provide resilience to these effects, if the impacted views are screened from the dataset, as the remaining views may be sufficient for successful analysis. In this study, we discuss how the number of available viewing angles impacts aerosol and ocean color retrieval uncertainties, as applied to two versions of the HARP instrument. AirHARP is an airborne prototype that was deployed in the ACEPOL field campaign, while HARP2 is an instrument in development for the upcoming NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission. Based on synthetic data, we find that a total of 20–30 angles across all bands (i.e., five to eight viewing angles per band) are sufficient to achieve good retrieval performance. Following from this result, we develop an adaptive multi-angle polarimetric data screening (MAPDS) approach to evaluate data quality by comparing measurements with their best-fitted forward model. The FastMAPOL retrieval algorithm is used to retrieve scene geophysical values, by matching an efficient, deep learning-based, radiative transfer emulator to observations. The data screening method effectively identifies and removes viewing angles affected by thin cirrus clouds and other anomalies, improving retrieval performance. This was tested with AirHARP data, and we found agreement with the High Spectral Resolution Lidar-2 (HSRL-2) aerosol data. The data screening approach can be applied to modern satellite remote sensing missions, such as PACE, where a large amount of multi-angle, hyperspectral, polarimetric measurements will be collected.

Application of InSAR satellite method for mapping of active landslides in Bulgaria – opportunities and perspectives

Abstract. Landslides are geological phenomena that are spread on Bulgarian territory mainly along the northern Black Sea coast and on the right banks of the Danube in the western part of the country. Mitigation of the negative effects of these destructive geological phenomena is the compilation of inventory maps of their distribution and registers with the main characteristics of the individual landslides. Conventional methods for making such maps are time-consuming and resource-intensive. Modern satellite, air and ground-based remote sensing technologies facilitate the production of landslide maps, reducing the time and resources required to compile and systematically update them. In this paper, we demonstrate the applicability of Differential Sentinel-1A satellite SAR interferometry (DInSAR) to assess the movement activity and use the information for further updating the national landslide inventories in Bulgaria. We perform several analyses based on multi-temporal InSAR techniques of Sentinel-1A data over selected areas prone to landslides. The use of new opportunities for free access to satellite images, which can be applied in conjunction with other methods, greatly facilitates the processes of inventory, mapping and study of landslides.

An Automated Snow Mapper Powered by Machine Learning

Snow preserves fresh water and impacts regional climate and the environment. Enabled by modern satellite Earth observations, fast and accurate automated snow mapping is now possible. In this study, we developed the Automated Snow Mapper Powered by Machine Learning (AutoSMILE), which is the first machine learning-based open-source system for snow mapping. It is built in a Python environment based on object-based analysis. AutoSMILE was first applied in a mountainous area of 1002 km2 in Bome County, eastern Tibetan Plateau. A multispectral image from Sentinel-2B, a digital elevation model, and machine learning algorithms such as random forest and convolutional neural network, were utilized. Taking only 5% of the study area as the training zone, AutoSMILE yielded an extraordinarily satisfactory result over the rest of the study area: the producer’s accuracy, user’s accuracy, intersection over union and overall accuracy reached 99.42%, 98.78%, 98.21% and 98.76%, respectively, at object level, corresponding to 98.84%, 98.35%, 97.23% and 98.07%, respectively, at pixel level. The model trained in Bome County was subsequently used to map snow at the Qimantag Mountain region in the northern Tibetan Plateau, and a high overall accuracy of 97.22% was achieved. AutoSMILE outperformed threshold-based methods at both sites and exhibited superior performance especially in handling complex land covers. The outstanding performance and robustness of AutoSMILE in the case studies suggest that AutoSMILE is a fast and reliable tool for large-scale high-accuracy snow mapping and monitoring.

Vulnerability of Satellite Quantum Key Distribution to Disruption from Ground-Based Lasers.

Satellite-mediated quantum key distribution (QKD) is set to become a critical technology for quantum-secure communication over long distances. While satellite QKD cannot be effectively eavesdropped, we show it can be disrupted (or ‘jammed’) with relatively simple and readily available equipment. We developed an atmospheric attenuation and satellite optical scattering model to estimate the rate of excess noise photons that can be injected into a satellite QKD channel by an off-axis laser, and calculated the effect this added noise has on the quantum bit error rate. We show that a ground-based laser on the order of 1 kW can significantly disrupt modern satellite QKD systems due to photons scattering off the satellite being detected by the QKD receiver on the ground. This class of laser can be purchased commercially, meaning such a method of disruption could be a serious threat to effectively securing high-value communications via satellite QKD in the future. We also discuss these results in relation to likely future developments in satellite-mediated QKD systems, and countermeasures that can be taken against this, and related methods, of disruption.