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In this study, global satellite data were analyzed to determine trends in oceanic wind speed and significant wave height over the 33-year period from 1985 to 2018. The analysis uses an extensive database obtained from 31 satellite missions comprising three types of instruments—altimeters, radiometers, and scatterometers. The analysis shows small increases in mean wind speed and significant wave height over this period, with larger increases in extreme conditions (90th percentiles). The largest increases occur in the Southern Ocean. Confidence in the results is strengthened because the wind speed trends are confirmed by all three satellite systems. An extensive set of sensitivity analyses confirms that both the mean and 90th percentile trends are robust, with only small impacts caused by satellite calibration and sampling patterns.

The Arctic warms nearly four times faster than the global average, and aerosols play an increasingly important role in Arctic climate change. In the Arctic, sea salt is a major aerosol component in terms of mass concentration during winter and spring. However, the mechanisms of sea salt aerosol production remain unclear. Sea salt aerosols are typically thought to be relatively large in size but low in number concentration, implying that their influence on cloud condensation nuclei population and cloud properties is generally minor. Here we present observational evidence of abundant sea salt aerosol production from blowing snow in the central Arctic. Blowing snow was observed more than 20% of the time from November to April. The sublimation of blowing snow generates high concentrations of fine-mode sea salt aerosol (diameter below 300 nm), enhancing cloud condensation nuclei concentrations up to tenfold above background levels. Using a global chemical transport model, we estimate that from November to April north of 70° N, sea salt aerosol produced from blowing snow accounts for about 27.6% of the total particle number, and the sea salt aerosol increases the longwave emissivity of clouds, leading to a calculated surface warming of +2.30 W m−2 under cloudy sky conditions.Fine sea salt aerosols produced by blowing snow in the Arctic impact cloud properties and warm the surface, according to observations from the MOSAiC expedition.

Polyether block amide (PEBA) is an important thermoplastic polyester elastomer (TPE) owing to its low density and high resilience. Microcellular foaming can endow PEBA with significant potential in sports, medical, and industrial applications. However, with the current microcellular foaming technology, it remains challenging to obtain PEBA foams with stable shapes, which are critical for their mechanical properties. Therefore, microcellular foaming with CO2 and N2 as co‐blowing agents is utilized in this study to achieve mechanically robust PEBA foams by reducing the dimensional shrinkage. The introduction of N2 can effectively slow the diffusion rate of blowing agents into the air, providing support for the foam to resist external atmospheric pressure and effectively reducing the dimensional shrinkage of PEBA foams. Consequently, a stable foam shape is achieved with an expansion ratio of 7.9. Finally, the PEBA foams with excellent shrinkage resistance and mechanical properties are prepared, and the cell shrinkage mechanism is analyzed to study the effects of blowing agents and foaming methods on the structural evolution of TPE foams. This promising outcome paves way for their practical industrial applications. Microcellular foaming with CO2 and N2 as co‐blowing agents is developed to achieve mechanically robust PEBA foams by reducing the dimensional shrinkage. Compared with pure CO2 as blowing agents, the co‐blowing agents leads to significantly reduced shrinkage of PEBA foams after foaming and hence improved mechanical performance. The promising outcome paves way for developing high‐performance thermoplastic elastomer foams.

Parallel protection gap has the advantages of simple structure, good economy, and so on. It is widely used in lightning protection. However, the problem is that the arc’s self-extinguishing ability of the protection gap is poor and prone to tripping the line, hindering its further development. To address this problem, this paper proposes a method of connecting an electromagnet in series next to a protection gap and installing an arc-breaking grid at the gap. By changing the magnetic field distribution in the protective gap, while the arc is stretched, the arc is deflected to break on the arc-breaking grids, thus causing the arc to extinguish quickly. Through a finite element simulation platform, the arc simulation model of this protective gap was established based on the theory of magnetohydrodynamic (MHD) approach. The results of the study show that a fast arc quenching method for parallel protection gaps based on the magnetic blowing principle can extinguish the arc within 5 ms, an 89.4 percent reduction in arc extinguishing time compared to the traditional parallel spark gap. Its arc temperature plummeted to below 2000 K in a short time, which greatly reduces the arc energy and effectively improves the arc extinguishing effect of the protection gap.

This study mainly investigates the effect of the bottom-blowing regime of the ladle on the mixing time of the molten pool and the removal of inclusions, providing a process optimization scheme for the development of high-quality clean steel materials. In this study, a hydraulic model was first established at a 1:4 scale, and water modeling experiments were conducted. Based on the water modeling experiments, the optimal positions of the two bottom-blowing plugs were determined to be at 0.7R and 0.4R (R is the radius of the ladle bottom), with a relative angle of 90° between the two plugs. Further CFD (Computational Fluid Dynamics) simulation experiments were conducted, combined with the results of the water modeling experiments, to determine that under a total bottom-blowing argon flow of 800 L/min, when the flow rate of the plug at 0.7R is 600 L/min and at 0.4R is 200 L/min, the shortest mixing time of 36 seconds can be achieved, forming a more uniform flow field and an extended circulation zone. Under the optimized bottom-blowing regime, the removal rate of alumina inclusions in the molten steel increased from 82.8% (original scheme) to 97.5%.

Wind shapes high‐altitude winter snow mass balance and influences water resources by controlling snow accumulation, erosion, and sublimation loss, yet accurately quantifying these processes remains challenging in high‐altitude regions like the Tibetan Plateau due to complex wind‐snow interactions and extreme measurement conditions. To address these challenges, we present an integrated observation system to monitor wind‐blown snow processes and develop a Gaussian kernel‐based probabilistic classification method that incorporates measurement uncertainties to identify wind‐driven snow events. This method enables more robust analysis of rapid snow mass changes compared to traditional classification. The study site is in the northeastern Tibetan Plateau at 4,147 m elevation with strong winds and frequent winter snowfall. Our results show that wind‐driven snow deposition and erosion events account for 68.5% of observed snow mass changes, while purely precipitation‐driven accumulation events only contribute 3.1% of total changes, with the remaining 28.4% being mixed events involving both precipitation and wind‐driven processes. Our results provide observational evidence that blowing snow sublimation is amplified when wind speeds exceed approximately 8 m s−1 ${\\mathrm{s}}^{-1}$, highlighting the pivotal role of suspended particles in enhancing evapotranspiration losses. This continuous wind‐driven reshaping of the snowpack leads to rapid changes in snow depth, density, and even thermal properties, challenging traditional modeling approaches that assume more gradual layer evolution. This study provides a robust method for identifying wind‐driven snow events and quantifying their influences on snow mass balance. Our findings emphasize the importance of incorporating wind‐driven processes in high‐altitude snow models and monitoring systems to better understand snow dynamics.

Reinforcement learning is applied to the development of control strategies in order to reduce skin friction drag in a fully developed turbulent channel flow at a low Reynolds number. Motivated by the so-called opposition control (Choi et al., J. Fluid Mech., vol. 253, 1993, pp. 509–543), in which a control input is applied so as to cancel the wall-normal velocity fluctuation on a detection plane at a certain distance from the wall, we consider wall blowing and suction as a control input, and its spatial distribution is determined by the instantaneous streamwise and wall-normal velocity fluctuations at distance 15 wall units above the wall. A deep neural network is used to express the nonlinear relationship between the sensing information and the control input, and it is trained so as to maximize the expected long-term reward, i.e. drag reduction. When only the wall-normal velocity fluctuation is measured and a linear network is used, the present framework reproduces successfully the optimal linear weight for the opposition control reported in a previous study (Chung & Talha, Phys. Fluids, vol. 23, 2011, 025102). In contrast, when a nonlinear network is used, more complex control strategies based on the instantaneous streamwise and wall-normal velocity fluctuations are obtained. Specifically, the obtained control strategies switch abruptly between strong wall blowing and suction for downwelling of a high-speed fluid towards the wall and upwelling of a low-speed fluid away from the wall, respectively. Extracting key features from the obtained policies allows us to develop novel control strategies leading to drag reduction rates as high as 37 %, which is higher than the 23 % achieved by the conventional opposition control at the same Reynolds number. Finding such an effective and nonlinear control policy is quite difficult by relying solely on human insights. The present results indicate that reinforcement learning can be a novel framework for the development of effective control strategies through systematic learning based on a large number of trials.

The objective of the present study is to characterize a rain tunnel that is used for performance testing of aircraft windshield rain removal systems. The rain tunnel in the present study is an open jet wind tunnel with six full cone pressure swirl nozzles arranged at its outlet. Experiments are conducted with water at room temperature as the working medium. The influence of total water supply flow rate and air velocity on the blowing-rain intensity and uniformity is studied. The total water supply flow rate varies from 0.57 m 3 /h to 1.03 m 3 /h, while the pressure at the inlet of the nozzle ranges from 1.44 bar to 6.52 bar. The air velocity of 30 m/s, 40 m/s, and 50 m/s is studied. A special test setup has been designed for measurements of the blowing-rain intensity and uniformity. Experimental results indicate that the blowing-rain intensity and uniformity both increase with the increasing total water supply flow rate and decrease with the increasing air velocity.

Antarctic Bottom Water has been warming in recent decades throughout most of the oceans and freshening in regions close to its Indian and Pacific sector sources. We assess warming rates on isobars in the eastern Pacific sector of the Southern Ocean using CTD data collected from shipboard surveys from the early 1990s through the late 2010s together with CTD data collected from Deep Argo floats deployed in the region in January 2023. We show cooling and freshening in the temperature‐salinity relation for water colder than ∼0.4°C. We further find a recent acceleration in the regional bottom water warming rate vertically averaged for pressures exceeding 3,700 dbar, with the 2017/18 to 2023/24 trend of 7.5 (±0.9) m°C yr−1 nearly triple the 1992/95 to 2023/24 trend of 2.8 (±0.2) m°C yr−1. The 0.2°C isotherm descent rate for these same time periods nearly quadruples from 7.8 to 28 m yr−1. Plain Language Summary Cold winds blowing over polynyas (areas of ice‐free water) on the Antarctic continental shelf create sea ice, forming very cold and somewhat salty, hence very dense, waters. These dense shelf waters descend the continental slope to the abyss, mixing with adjacent waters to form Antarctic Bottom Water (AABW). AABW spreads northward from there, filling much of the global abyssal ocean as it mixes with warmer, lighter waters above. AABW has been warming on pressure surfaces, freshening and cooling on density surfaces, and reducing in volume (contracting). These changes are likely a result of melting Antarctic ice sheets, which freshen the shelf waters, making them less dense, hence less able to sink to the bottom. We compare profiles of ocean temperature and salinity in the eastern Pacific sector of the Southern Ocean collected in 2023 and 2024 by robotic freely drifting profilers to data collected from ships from the early 1990s to the late 2010s. We find all of the above listed changes, but also acceleration of the warming, with the rate from 2017/18 to 2023/24 being nearly triple the rate from 1992/95 to 2023/24. The contraction rate has nearly quadrupled. This acceleration has been predicted by high‐resolution climate model simulations. Key Points Antarctic Bottom Water (AABW) changes in the east Pacific sector of the Southern Ocean are assessed using Deep Argo and ship‐based CTD profiles Bottom water warming rates from 2017/18 to 2023/24 nearly triple compared to 1992/95 to 2023/24 rates, contraction rates nearly quadruple AABW cooling and freshening on isopycnals is also observed in the region, relative to older Circumpolar Deep Water

Analysis of the effect of argon bottom blowing on stirring and refining in a ladle was carried out using numerical simulation based on a 250-ton ladle. The flow field inside the ladle was calculated for different bottom-blowing hole angles and radial positions, and the influence of the distance between the bottom-blowing holes and refining effect was investigated. The results indicate that as the bottom-blowing flow rate increases, the rate of change in the dead zone inside the ladle gradually decreases and drops sharply at 950 L/min. When the angle between the two bottom-blowing holes increases from 90° to 180 ° under the same bottom-blowing flow rate, the maximum velocity at the steel-liquid interface decreases and the average flow velocity of the steel liquid increases. When the bottom-blowing aperture is at a position of r/R = 0.5, the stirring effect of the steel liquid is good, and when r/R = 0.67 is arranged. When the spacing ratio is constant, the relative position changes, and the bottom-blowing effect hardly changes. When the spacing ratio increases from 0.707 to 1, the mixing effect of the steel liquid improves, and the refining effect of the steel-liquid interface decreases.