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The ionosphere plays a critical role in the electromagnetic waves in communication systems such as the global positioning system (GPS). However, it is suspected that the strong convection during the tropical cyclone (TC) events can be a trigger to anomalous electron density variation in the ionosphere. This study analyzed the variation of three ionosphere-related parameters based on the GPS data including scintillation index S4, cycle slips, and total electron content (TEC) rate (TECR) during the tropical cyclone event (the 2013 TC Usagi) in the Hong Kong region. The results showed that the ionosphere-related parameters had a consistent significant increase on the second day after the Usagi made landfall near Hong Kong. Consequently, the positioning performance of GPS precise point positioning (PPP) and relative positioning modes was degraded. The degradation was ~ 138%, ~ 181%, and ~ 460% in the east (root mean square (RMS) 0.050 m), north (RMS 0.045 m), and up (RMS 0.185 m), respectively, compared with the RMS of 0.021 m in the east, 0.016 m in the north, and 0.033 m in the up on the normal day. Regarding the relative positioning, the positioning errors in the east (RMS 0.134 m) and north (RMS 0.118 m) directions were ~ 7.1 and ~ 7.9 times, respectively, as large as the RMS of 0.019 m in the east and 0.015 m in the north on the normal day. The positioning errors in the up (RMS 0.513 m) direction were ~ 12.2 times larger than the RMS of 0.042 m on the normal day.

Precipitable water vapor (PWV) is one of the crucial driving forces for tropical cyclone (TC) genesis. Under the impact of global warming, TCs have changed their way to concentrate PWV from the ambient atmosphere. This study starts with the asymmetric characteristics of PWV in the TC's north and south sides using altimetry‐satellite‐based PWV profiles paired with 367 TCs over the western Pacific Ocean between 2008 and 2020. The results suggest that the TC‐concentrated PWV has a north‐leaning and south‐leaning property over the western North Pacific (WNP) and western South Pacific (WSP), respectively. Moreover, it is observed that the radius of TC‐concentrated PWV has broadened by 5.44% (5.83%) over the WNP (WSP) from 2008 to 2020. In contrast, the PWV gradient has decreased by 23.5% (17.5%) over the WNP (WSP). Our findings highlight that the TC‐concentrated PWV can be used as an important indicator of TC responses to global warming. Plain Language Summary Global warming has deepened people's impression in tropical cyclone (TC) in the recent decades. For instance, the asymmetrical properties of precipitable water vapor (PWV) in the TC's north and south sides have a sensitive response to global warming. The sea surface temperature warmed at a rate of 0.047 (0.045) °C per year over the western North (South) Pacific Ocean between 2008 and 2020, which directly results in an increase of 0.16 (0.31) kg·m−2 yr−1 in PWV. This makes it easier for TCs to concentrate more water vapor into the TC's vortex area. Statistically, the TC‐concentrated PWV radius expanded by 5.44% (5.83%) or 4.0 (4.7) km·yr−1 over the western North (South) Pacific Ocean during the period 2008–2020. This finding provides another clue to TC's slowdown of translation speed and the increased TC‐induced flood risk in the recent decades. Key Points The tropical cyclone (TC)‐concentrated precipitable water vapor (PWV) features a north‐leaning (south‐leaning) property for TCs over western North Pacific (WNP) (western South Pacific (WSP)) ocean basins The TC‐concentrated PWV area outstretches by 5.44% (5.83%) between 2008 and 2020 over WNP (WSP) ocean basins The spatial gradient of TC‐concentrated PWV decreased by 23.5% (17.5%) between 2008 and 2020 over WNP (WSP) ocean basins

Aiming at the problems of low accuracy and large computation in the task of PCB defect detection. This paper proposes a lightweight PCB defect detection algorithm based on YOLO. To address the problem of large numbers of parameters and calculations, GhostNet are used in Backbone to keep the model lightweight. Second, the ordinary convolution of the neck network is improved by depthwise separable convolution, resulting in a reduction of redundant parameters within the neck network. Afterwards, the Swin-Transformer is integrated with the C3 module in the Neck to build the C3STR module, which aims to address the issue of cluttered background in defective images and the confusion caused by simple defect types. Finally, the PANet network structure is replaced with the bidirectional feature pyramid network (BIFPN) structure to enhance the fusion of multi-scale features in the network. The results indicated that when comparing our model with the original model, there was a 47.2% reduction in the model’s parameter count, a 48.5% reduction in GFLOPs, a 42.4% reduction in Weight, a 2.0% reduction in FPS, and a 2.4% rise in mAP. The model is better suited for use on low-arithmetic platforms as a result.

The reduction of Arctic sea ice concentration (SIC) is a key indicator of global warming. In September 2012, SIC reached its lowest recorded value. Since then, sea ice melt has slowed down, showing a linear trend of only −0.4±6.8%/decade from 2012 to 2023, compared to −11.3±3.3%/decade from 1996 to 2011. Here, we demonstrate that the recent slowdown in September sea ice melt is closely coupled with the multi-decadal variability of the preceding summer North Atlantic Oscillation (NAO), which has transitioned from the lowest point of its negative phase in the early 2010s to a positive phase. During this shift, decreased heat and moisture, along with reduced downward longwave radiation, have contributed to offsetting the long-term decline, leading to a slowdown in Arctic sea ice melting. Additionally, the Atlantic Multidecadal Oscillation plays a primary role in driving the interdecadal variability of the NAO and Arctic sea ice by modulating wave-mean flow interactions. This study shows that the slowdown in September Arctic sea ice loss is linked to the shift towards a positive phase of the North Atlantic Oscillation, which reduces heat and moisture transport and longwave radiation, partially offsetting the long-term decline of Arctic sea ice.

Space weather can impede normal aviation operations through communication blackouts, GNSS‐based navigation and surveillance failures, and elevated cosmic radiation, consequently resulting in necessary flight plan adjustments and considerable economic costs. Although space weather effects have been heavily emphasized, the literature on the economic effects on aviation is limited. In this study, we estimate the economic impacts from the perspective of air traffic management, assuming an extremely strong space weather event like the 2003 Halloween solar storm would occur in 2019 with a booming air transport industry in recent years. We find that (a) as the high‐frequency communication blackouts may lead to polar flight rerouting and cancellations, possible daily economic costs could range from €0.21 million to €2.20 million per day; (b) during the satellite navigation failure period in the continental United States, as aircraft utilizes ground navigation aids as a backup, the increased flying time and disrupted descent approach operations may lead to additional cost of €2.43 million; (c) a surveillance failure can reduce airspace capacity and increase the workload of air traffic controllers, resulting in fatigue and perhaps risking flight safety; (d) to prevent massive cosmic radiation exposure, the economic costs of flight cancellations can be from €2.77 million to €48.97 million, depending on the cosmic radiation dose limits for a given plan. Our study indicates that severe space weather events may briefly disrupt normal aviation operations and cause substantial economic losses if future aviation equipment and technology are fragile to its effects.

As demand for flights increases, the global aviation industry must transform to become more sustainable. Here we propose six pathways to set aviation on a path to a greener future that include innovations in aviation fuel, management, and regulations.

This study employs numerical simulation methods to systematically analyze the multiphase flow and heat transfer characteristics in a circulating fluidized bed flue gas desulfurization (CFB-FGD) reactor handling ascharite ore roasting flue gas. Based on the simulation results, key structural optimization strategies are proposed. A three-dimensional mathematical model was developed based on the Fluent 19.1 platform, and the multiphase flow process was simulated using the Eulerian-Lagrangian method. The study examined the effects of venturi tube structure, atomized water nozzle installation height, and gas injection disruptor configuration on reactor performance. Optimization strategies for key structural components were systematically evaluated. The results show that the conventional inlet structure leads to significant non-uniformity in the velocity field. Targeted adjustments to the dimensions of venturi tubes at different positions markedly improve the velocity distribution uniformity. Reducing the atomized water nozzle installation height from 1.50 m to 0.75 m increased the temperature distribution uniformity index in the middle part of the straight pipe section by 5.5%. Moreover, a gas injection disruptor was installed in the upper part of the straight pipe section of the CFB-FGD reactor. Increasing the gas injection velocity from 15 m/s to 30 m/s increased the average residence time of desulfurization sorbents by 17.0%. This increase effectively enhances gas–solid mixing within the CFB-FGD reactor. The optimization strategies described above significantly reduced the extent of flow dead zones and low-temperature regions in the CFB-FGD reactor and improved flow conditions. This study provides important theoretical and technical support for the optimization and industrial application of CFB-FGD technology for ascharite ore roasting flue gas.

Winter cold extremes (WCEs) frequently plague densely populated areas of Asia, leading to substantial economic losses and even fatalities. It has been found that the late autumn sea ice concentration (SIC) anomalies in the northern (SICN) and southern Arctic (SICS) are significantly positively and negatively correlated with the occurrence frequency of WCE in Asia, respectively (Wang and Su 2024). Our study demonstrates that the impacts of SICN and SICS have strengthened after 1999/2000. Specifically, before 1999/2000, the influences of SICN and SICS on the Asian WCE (AWCE) were relatively weak, possibly related to the weak intensity of SICS and the limited correlation between SICN and SICS. After 1999/2000, the interannual variability of SICS became larger and anti-correlated with that of SICN, resulting in a stronger teleconnection between the Arctic SIC and AWCE. It is revealed that after 1999/2000, the greater loss of SICS modified atmospheric stability through changes in surface heat fluxes and surface upward longwave radiation fluxes. This alteration weakened the magnitudes of westerly winds and increased the frequency of blocking events over the northern Eurasian continent, leading directly to a higher occurrence of cold extremes in Asia. These interdecadal differences in the influence of Arctic SIC on AWCE may be associated with long-term climate change.

Satellite navigation systems are vulnerable to space weather disturbances, which can degrade positioning accuracy and potentially increase the collision risk of unmanned aerial vehicles (UAVs). This study investigates the influence of navigation errors caused by ionospheric scintillation on UAV encounter scenarios. Two route configurations are examined: parallel routes with varying lateral separations and crossing routes with different heading angles. Collision probabilities are estimated under both quiet and storm conditions by incorporating navigation error models representative of space weather impacts. Results show that during geomagnetic storm conditions, collision probabilities increase by several orders of magnitude compared to quiet conditions, with the magnitude of risk escalation depending on route geometry and separation distance. For parallel routes, reduced lateral spacing amplifies the effect of navigation errors, while for crossing routes, larger heading angles exacerbate the probability of close encounters. These findings demonstrate that space weather‐induced navigation degradation can meaningfully alter UAV operational safety, particularly in dense traffic environments. The study underscores the need for incorporating space weather impacts into UAV risk assessment frameworks and for developing mitigation strategies to ensure safe integration of UAVs into airspace systems.

The uncertain output of variable renewables adds significant challenges to the generation of affordable, reliable, and sustainable power sources in a country or region. Therefore, we propose a new stochastic nonlinear multi-objective model to optimize the power generation structure in 31 provinces of China. Considering variable renewable integration, we use Monte Carlo simulation to describe the randomness and uncertainty of renewable power output. The learning curve in the exponential expression is used to describe the nonlinear relationship between generation cost and installed capacity. The optimized results show that China can substitute fossil power with clean power. Renewable power will account for more than 42% of total power in the optimal power generation structure in 2040. In particular, the annual average growth rate of non-hydro renewable generation is expected to be 12.06%, with solar photovoltaic (PV) power growing the most by 17.95%. The share of renewable power exceeds that of thermal power in 14 provinces, and PV power represents the highest proportion at 30.21%. Reducing transmission capacity can promote the development of advantageous power in each region, such as wind power in the Northwest region and PV power in the South region, with the share increasing by 36.33% and 132.59%, respectively.