Search Results (11)

Accurate delineation of glacier extent is crucial for monitoring glacier degradation in the context of global warming. Satellite remote sensing with high spatial and temporal resolution offers an effective approach for large-scale glacier mapping. However, persistent cloud cover limits its application on the Tibetan Plateau, leading to substantial omissions in glacier identification. Therefore, this study proposed a novel sub-cloudy glacier extraction model (SCGEM) designed to extract glacier boundaries from cloud-affected satellite images. First, the cloud-insensitive characteristics of topo-graphic (Topo.), synthetic aperture radar (SAR), and temporal (Tempo.) features were investigated for extracting glaciers under cloud conditions. Then, a transformer-based generative adversarial network (GAN) was proposed, which incorporates an image reconstruction and an adversarial branch to improve glacier extraction accuracy under cloud cover. Experimental results demonstrated that the proposed SCGEM achieved significant improvements with an IoU of 0.7700 and an F1 score of 0.8700. The Topo., SAR, and Tempo. features all contributed to glacier extraction in cloudy areas, with the Tempo. features contributing the most. Ablation studies further confirmed that both the adversarial training mechanism and the multi-task architecture contributed notably to improving the extraction accuracy. The proposed architecture serves both to data clean and enhance the extraction of glacier texture features. Full article

Bigeye grunt (Brachydeuterus auritus) is a dominant fish species and mostly a major target species in both artisanal and industrial fisheries in the coastal waters of Sierra Leone. It was listed as near threatened in 2015 by the International Union for Conservation of Nature (IUCN) Red List. Although this species has been repeatedly assessed as overexploited by the Fishery Committee for the Eastern Central Atlantic (CECAF) in the majority of its range in the Eastern Central Atlantic, there have never been studies of stock assessment in the coastal waters of Sierra Leone. We conducted a study on the population dynamics of bigeye grunt in the coastal waters of Sierra Leone, which is crucial for completing the resource status of this species in the Eastern Central Atlantic. The results showed that the bigeye grunt had a wide distribution in the coastal waters of Sierra Leone, with significant spatiotemporal variation characteristics in biomass and abundance. The growth parameters of bigeye grunt varied across different months, but all E values were below 0.5, indicating that no overfishing occurred. These findings were further corroborated by the results of the Length-Based Bayesian Biomass Estimation method (LBB). The results of the Generalized Additive Model (GAM) show that there is a certain nonlinear relationship between the resource abundance of the bigeye grunt and both environmental factors and geographical locations, among which the influence of latitude is the greatest. This study posits that the bigeye grunt in Sierra Leone’s coastal waters exhibits moderate exploitation potential. The findings are anticipated to provide a scientific framework for informing evidence-based management strategies for this fishery resource. Full article

Surveillance video analytics encounters unprecedented challenges in 5G and IoT environments, including complex intra-class variations, short-term and long-term temporal dynamics, and variable video quality. This study introduces Edge-Enhanced TempoFuseNet, a cutting-edge framework that strategically reduces spatial resolution to allow the processing of low-resolution images. A dual upscaling methodology based on bicubic interpolation and an encoder–bank–decoder configuration is used for anomaly classification. The two-stream architecture combines the power of a pre-trained Convolutional Neural Network (CNN) for spatial feature extraction from RGB imagery in the spatial stream, while the temporal stream focuses on learning short-term temporal characteristics, reducing the computational burden of optical flow. To analyze long-term temporal patterns, the extracted features from both streams are combined and routed through a Gated Recurrent Unit (GRU) layer. The proposed framework (TempoFuseNet) outperforms the encoder–bank–decoder model in terms of performance metrics, achieving a multiclass macro average accuracy of 92.28%, an F1-score of 69.29%, and a false positive rate of 4.41%. This study presents a significant advancement in the field of video anomaly recognition and provides a comprehensive solution to the complex challenges posed by real-world surveillance scenarios in the context of 5G and IoT. Full article

In order to continuously promote water conservation efforts to alleviate the pressure of water diversion, water footprint (WF) is used as an effective tool to measure water utilization in the water-receiving areas of the Middle Route and Eastern Route of the South-to-North Water Diversion Project (SNWDP). The tempo-spatial variations of WF and spatial equilibrium of water footprint intensity (WFI) in the study area are quantified using the Mann–Kandle trend test, Sen’s slope, and Dagum Gini coefficient decomposition method for the years of 2005–2020. The results show that WF has a significant decreasing trend (Sen’s slop < 0, significant level < 0.05) in 17 cities in the study area, whereas WF shows a significant increasing trend (Sen’s slop > 0, significant level < 0.05) in 10 cities. Cities in the water-receiving areas are categorized into three types based on the contribution of the water utilization sector to changes in WF as follows: agriculture water-dominated city (AD), domestic and ecological water-dominated city (DED), and virtual water trade-dominated city (VWTD). Accordingly, targeted water conservation recommendations are made for these three kinds of cities, and it is suggested that AD, DED, and VWTD cities need to focus on advanced irrigation technologies, water reuse, and trade restructuring, respectively. The overall Gini coefficient of WFI fluctuates between 0.219 and 0.267 in the water-receiving areas of the Middle Route, which is dominated by the differences in city level. However, it fluctuates between 0.412 and 0.278 in the water-receiving areas of the Eastern Route, which is dominated by the differences in provincial level. Accordingly, water conservation hotspots are determined at the city level in the Middle Route and at the provincial level in the Eastern Route with different water management policies. These results provide a scientific support for water conservation management in the water-receiving areas of the SNWDP, as well as a methodological reference for the tempo-spatial characteristics of WF and their implications for water conservation. Full article

Agriculture is one of the dominant industries in the Mun River Basin, but farmlands are frequently affected by floods and droughts due to the water resource management mode of their rainfed crop, especially in the context of climate change. Drought risk assessment plays an important role in the Mun River Basin’s agricultural sustainable development. The objective of this study was to identify the tempo-spatial variation in dryness and wetness patterns; the drought intensity, frequency, and duration; and the potential causes behind drought using the methods of the standardized precipitation evapotranspiration index (SPEI), ensemble empirical mode decomposition (EEMD), correlation analysis, and the Pettitt test over the basin. Results showed that the Mun River Basin underwent a drying climate pattern, which is explained by the significant decreasing trend of SPEI_12M during the study period. In addition, the downstream area of the Mun River Basin was subjected to more intense, extreme dryness and wetness events as the decreased amplitude of SPEI_12M and SPEI_3M was higher than that over the upper and middle reaches. Drought intensity presented a remarkable decadal variation over the past 36 years, and an average 7% increase per decade in the drought intensity was detected. Besides, there have been more mild and moderate droughts frequently appearing over the Mun River Basin in recent decades. For the underlying causes behind the drought condition, on the one hand, the shortened precipitation day over the rainy season accounted more for the intense drought events than the precipitation amount. On the other hand, El Nino Southern Oscillation (ENSO)-brought sea surface temperature anomalies aggravated the potential evapotranspiration (ETr), which might be closely related to the drought intensity and frequency variation. These tempo-spatial maps of dryness and wetness and drought occurrence characteristics can be conducive to local stakeholders and agricultural operators to better understand the agriculture industry risks and vulnerabilities and properly cope with pre-disaster planning and preparedness and post-disaster reconstruction over the Mun River Basin. Full article

The Taklamakan Desert and the Gobi Desert in East Asia constitute the second-largest sources of dust in the world. In particular, dust originating from the Gobi Desert is more susceptible to long-range transport, with consequent impacts in downwind Asian countries and the Northwest Pacific region. Two intensive dust events (the 3·15 dust event and the 3·28 dust event) were experienced in North China in March 2021. The 3·15 dust process was rated as the most intensive dust process in China in the past 10 years. In this study, by using a combination of spaceborne remote sensing datasets from geostationary and polar-orbiting satellites, ground-based columnar observations of aerosol optical parameters, meteorological reanalysis data, and backward trajectory simulations of air masses, the transport pathways and the three-dimensional structure characteristics of dust aerosols during the transport of the two dust events in March 2021 were cross-validated. The results of the study indicated that the two dust events were induced by the Mongolian cyclone. Due to the different configurations of the ground meteorological system conditions, a backflow process occurred during the 3·15 dust event transmission process. After passing over North China and the Bohai Sea, the direction of transport of the dust plume was reversed. The wind deflected from northwest to northeast, and the dust reached the eastern coastal areas of China and was finally deposited on land. The 3·28 dust event exhibited aerosol stratification in the transport path, the higher pure dust layer reached up to 9 km height, and the lower layer underwent aerosol mixing and became a polluted dust aerosol. This study implies that the investigation of dust aerosol transport and the deposition processes, the impact on the ocean, and the impact of marine aerosols on land also needs to be taken into consideration; the integration of advanced satellites and ground-based remote sensing data, the meteorological reanalysis data and the backward trajectories simulation, which complemented and verified each other, can enhance the ability to delineate the transport pathways and the three-dimensional structural characteristics of dust events. Full article

World Heritage is of high historical, artistic, and scientific value and represents wealth created by human beings or nature that cannot be replaced. In this paper, the tempo–spatial characteristics of World Heritage and its traffic accessibility were assessed in China using statistical and spatial analysis methods. The results showed that development of Chinese World Heritage experienced exploratory, evolution, accelerated development, and stable development phases. To date, there are 55 World Heritage Projects in China, including 37 Cultural Heritage, 14 Natural Heritage, and 4 mixed double heritage projects. Based on the spatial analysis, global spatial correlation of these heritage sites was not significant while the local spatial correlation was significant. The majority of the heritage sites were distributed in the east–central regions of China, and the hotspots were also concentrated in these regions. In addition, an assessment of inter-regional accessibility indicated that 63.18% of heritage sites could be reached within one hour from a city center and the average time taken to reach a heritage site was at 1.03 h in the local city. Time cost was low and accessibility was good. Additionally, an analysis of the overall accessibility showed that the average time cost of the World Heritage Sites was 25.51 h. Overall accessibility in the central plain region of China was very high, with a time cost of <15 h. The overall accessibility in the western mountains and northeastern regions was very limited. In general, the development of China’s World Heritage still has great potential and strong traffic accessibility, which can effectively promote the development of heritage tourism. Meanwhile, heritage tourism can also effectively promote the development of local economies under the principle of protection priority. Full article

The requirement of timeliness is increasing while obtaining precise tempo-spatial information with the development of global navigation satellite systems (GNSSs). Due to the poor network environment and communication conditions in some regions or application scenarios, it is difficult for users to receive real-time (RT) precise products. The hourly updated ultra-rapid products with low latency and high accuracy are of great interest in GNSS real-time and near-real-time fields. However, it is difficult to achieve the high-rate one-hourly updated precise clock estimation (PCE); since many ambiguity parameters need to be estimated, the computation is time-consuming. At present, the highest time resolution of ultra-rapid clock offsets is 15 min. The low samplings affect the prediction accuracy of clock offsets and the precise point positioning (PPP) performances. To meet these requirements, we proposed an efficient method and design a new framework for high-rate one-hourly updated ultra-rapid PCE. We modified the epoch-difference (ED) PCE model in the parameter estimation. According to the characteristics of the modified ED PCE model, the Open Multi-Processing (OpenMP) and Intel Math Kernel Library (MKL) technologies are used to construct a parallel system to realize the parallelism among satellites, epochs, and stations. The comprehensive assessment in the precision of clock offsets and PPP performances is conducted. The result demonstrates that the one-hourly updated multi-GNSS clock offsets with 30 s sampling can be obtained within 20 min. The estimated clock offsets accuracy increases with the improvement of the time resolution. The STD and RMS are improved by (0.97 to 9.09% and 0.12 to 5.56%) in the observation session, (2.82 to 23.08% and 0.95 to 9.09%) in the first hour of the prediction session, and (0.11 to 3.85% and 0.12 to 4.19%) in the second hour of the prediction session compared with low-rate products, respectively. The high-rate one-hourly updated ultra-rapid clock offsets significantly improves the RT-PPP performances. The positioning accuracy can be improved by 1.52~25.74%, and the convergence time can be improved by 21.96~65.75%. The RT-PPP performances are basically the same as GeoForschungsZentrum Potsdam (GFZ) rapid products and slightly better than the Center National d’Etudes Spatiales (CNES) RT products (CLK93). The one-hourly updated ultra-rapid products with low latency, high accuracy, and not limited by network conditions can be well applied to real-time or near real-time applications and research. Full article

Dramatic changes in land use/cover (LULC) patterns have taken place in the Three Gorges Reservoir Area (TGRA) after the construction of the Three Gorges Dam, which have led to hydrological and environment alterations. In this study, eight land use scenarios from 1980 to 2018 were used to evaluate the impact of LULC changes on runoff and nutrient load in the TGRA, using a validated version of the Soil & Water Assessment Tool (SWAT) model. Firstly, we analyzed the LULC characteristic. During the 38-year period, the LULC pattern showed an increase in forestland and a decrease in cropland. The cropland mainly changed into forestland. Construction land realized growth by encroaching mainly on cropland and forestland. Secondly, the temporal–spatial characteristics of runoff and nutrient load were analyzed. In the TGRA, surface runoff and nutrient load exhibited significant tempo-spatial heterogeneity. The runoff depth and the total nitrogen (TN) and total phosphorus (TP) loads increased through 1980 to 2018, and 2005 was a turning point. After 2005, the annual average change rate was larger than before 2005. The area with a larger runoff depth was mainly distributed in the head and middle region as well as on the left bank of the TGRA. The middle and tail region of the TGRA generated relatively higher TN and TP loads. Lastly, the contributions of LULC types on runoff and nutrient load were explored. Forestland had the highest contribution rate to surface runoff, followed by cropland. Cropland had the highest contribution rate to TN and TP, follow by forestland. This study can provide a better understanding of the hydrological consequences of LULC changes and help watershed management in the TGRA. Full article

Recent approaches in the research on walkable environments and wellbeing go beyond correlational analysis to consider the specific characteristics of individuals and their interaction with the immediate environment. Accordingly, a need has been accentuated for new human-centered methods to improve our understanding of the mechanisms underlying environmental effects on walking and consequently on wellbeing. Immersive virtual environments (IVEs) were suggested as a potential method that can advance this type of research as they offer a unique combination between controlled experimental environments that allow drawing causal conclusions and a high level of environmental realism that supports ecological validity. The current study pilot tested a walking simulator with additional sensor technologies, including biosensors, eye tracking and gait sensors. Results found IVEs to facilitate extremely high tempo-spatial-resolution measurement of physical walking parameters (e.g., speed, number of gaits) along with walking experience and wellbeing (e.g., electrodermal activity, heartrate). This level of resolution is useful in linking specific environmental stimuli to the psychophysiological and behavioral reactions, which cannot be obtained in real-world and self-report research designs. A set of guidelines for implementing IVE technology for research is suggested in order to standardize its use and allow new researchers to engage with this emerging field of research. Full article

Air pollution has become a critical issue in the urban areas of southeastern China in recent years. A complete understanding of the tempo-spatial characteristics of air pollution can help the public and governmental bodies manage their lives and work better. In this study, data for six criteria air pollutants (including particulate matter (PM_2.5, PM₁₀), carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃)) from 37 sites in nine major cities within Fujian Province, China were collected between January 2015 to December 2016, and analyzed. We analyzed the spatial and temporal variations of these six criteria pollutants, as well as the attainment rates, and identified what were the major pollutants. Our results show that: (1) the two-year mean values of PM_2.5 and PM₁₀ exceeded the Chinese National Ambient Air Quality Standard (CAAQS) standard I levels, whereas other air pollutants were below the CAAQS standard I; (2) the six criteria air pollutants show spatial variations (i.e. most air pollutants were higher in the city center areas, followed by suburban areas and exurban areas, except for O₃; and the concentrations of PM₁₀, PM_2.5, NO₂, O₃ were higher in coastal cities than in inland cities); (3) seasonal variations and the no attainment rates of air pollutants were found to be higher in cold seasons and lower in warm seasons, except for O₃; (4) the most frequently present air pollutant was PM₁₀, with PM_2.5 and O₃ being the second and third most frequent, respectively; (5) all the air pollutants, except O₃, showed positive correlations with each other. These results provide additional information for the effective control of air pollution in the province of Fujian. Full article