Search Results (17)

Flash drought (FD) is an extreme climate event that intensifies within days and exerts severe socio-environmental impacts. Its onset and evolution remain difficult to predict. Here, we quantify the spatio-temporal dynamics of FD across northern Xinjiang from 1961 to 2023 and identify the dominant driving factors. We apply linear trend detection, wavelet analysis, change-point detection, random forest (RF) modeling, and Pearson correlation. Results show that winter is becoming significantly wetter, whereas the annual signal and the other three seasons exhibit drying trends. After 1980, both FD frequency and FD duration increased; the longest single event lasted 40 days. Spatially, FD is concentrated in the Ili River Valley and the Altay region; the Akdala station recorded the highest count (nine events). Duration, rather than frequency, peaks on the northern slope of the Tianshan Mountains, where the maximum length reaches 40 days. RF importance ranks the Pacific Decadal Oscillation (PDO) as the leading driver (20.9%), followed by air temperature (17.8%); the sunspot index contributes only 6.1%. Full article

An overview of seasonal variations in glycaemic patterns in children and young adults with type 1 diabetes has been addressed in a previous work, which paved the way for an in-depth study involving not only traditional Multiple Dose Injection (MDI) therapy, but also a comparative analysis with the use of Advanced Hybrid Closed-Loop (AHCL) insulin pumps. The widespread use of Flash Glucose Monitoring (FGM) and Continuous Glucose Monitoring (CGM) systems, as well as dedicated platforms for synchronizing and storing CGM reports, has facilitated an efficient approach to analyzing glycaemic patterns. The effect of environmental parameters on glycemic trends undoubtedly has a clinical relevance, which however can be appropriately managed by knowing the responses in patients treated with different therapeutic approaches. In this sense, it is possible to evaluate how the glycemic trend in diabetic patients, in relation to external temperatures, responds differently to therapies. In this work, the response, in terms of glucose level, in diabetic patients was analyzed, according to the different therapeutic approaches and in relation to variations in external temperature. For the same period of the previous work (one year: Autumn 2022–Summer 2023), seasonal variations in CGM metrics (i.e., Time In Range—TIR, Time Above Range—TAR, Time Below Range—TBR and Coefficient of Variation—CV) were analyzed. The results show a better metabolic control, linked to the effect of the algorithm on the trend of glycaemia. However, the analysis focused on the heatwave of July 2023 highlights the role of extreme temperatures as a stress factor in the insulin pumps performance. A further focus was carried out on the comparison of glycaemic patterns during the school and non-school period for all patients until 21 years old. Results suggest that during the school period, glycaemic patterns, in patients treated with MDI, show a greater onset of hyperglycaemia. From all that has emerged, it appears clear that structured education on diabetes self-management for patients and their families is fundamental and must take into account multiple factors (type of therapy, daily activities, atmospheric temperature) in order to keep their effects under control. Full article

Flash droughts are a significant natural hazard, characterized by rapid onset and potential to cause substantial economic and environmental impacts. This study utilizes ERA5 soil moisture data to identify and define historical flash drought (FD) events in the Northeastern Aegean islands (specifically Chios, Lemnos, Lesvos and Samos). Hourly soil moisture data, spanning from 1990 to the present, covering three soil layers (0–7 cm, 7–28 cm and 28–100 cm), were analyzed and mapped onto a 0.1° × 0.1° grid with a native resolution of approximately 9 km. Additionally, the Standardized Precipitation Evapotranspiration Index (SPEI) was applied to the island of Lesvos, using precipitation and average temperature data from the local meteorological stations. The number and characteristics of these events—including frequency, duration, decline rate, magnitude, intensity, recovery rate and recovery duration—were produced to construct a regional overview of FD risk across the Northeastern Aegean Islands. These results reveal a considerable variability in the spatial, seasonal and temporal distribution of past FD events. Furthermore, this study highlights the value of using satellite-derived soil moisture data for identifying FD events and demonstrates that analyzing this data with field temperature and precipitation measurements enables a more localized and accurate interpretation of past events. This approach facilitates the definition of FD “hotspot” areas, which, when combined with further investigation, can lead to the development of a predictive FD model. Full article

Drought represents one of the most critical environmental hazards in arid and semi-arid regions, exerting profound impacts on ecological security and sustainable development. Nevertheless, many existing drought indices exhibit delayed responses to precipitation and soil moisture anomalies, thereby constraining their ability to characterize the rapid onset and evolution of drought events. To address this limitation, we propose the Standardized Temperature–Vegetation Drought Index (STVDI), which integrates precipitation, evapotranspiration, temperature, and vegetation dynamics within a Euclidean space framework and explicitly incorporates lag-response analysis. Taking the Mongolian Plateau (MP)—a key transition zone from taiga forest to desert steppe—as the study region, we constructed a 1 km resolution STVDI dataset spanning 2000–2021. Results reveal that over 88% of the MP is highly susceptible to flash droughts, with an average lag time of only 0.52 days, underscoring the index’s capacity for rapid drought detection. Spatial analysis indicates that drought severity peaks during March and April, with moderate drought conditions concentrated in central Mongolia and severe droughts prevailing across southwestern Inner Mongolia. Although trend analysis suggests a slight long-term alleviation of drought intensity, nearly 70% of the MP is projected to experience further intensification in the future. This study delivers the first high-resolution, low-lag drought monitoring dataset for the MP and advances theoretical understanding of drought propagation and lag mechanisms in arid and semi-arid ecosystems. Full article

Flash droughts, characterized by their rapid onset and severe impacts, have critical implications for the ecological environment and water resource security. However, inconsistent definitions of flash droughts have hindered scientific assessments of drought severity, limiting efforts in disaster prevention and mitigation. In this study, we propose a new method for explicitly characterizing flash drought events, with particular emphasis on the process of soil moisture recovery. The temporal and spatial evolution of flash droughts over the Yangtze River Basin was analyzed, and the severity of the extreme flash drought in 2022 was assessed by comparing its characteristics and impacts with those of three typical dry years. Additionally, the driving factors of the 2022 flash drought were evaluated from multiple perspectives. Results indicate that the new identification method for flash droughts is reasonable and reliable. In recent years, the frequency and duration of flash droughts have significantly increased, with the Dongting Lake and Poyang Lake basins being particularly affected. Spring and summer were identified as peak seasons for flash droughts, with the middle reaches most affected in spring, while summer droughts tend to impact the entire basin. Compared to 2006, 2011, and 2013, the flash drought in 2022 affected the largest area, with the highest number of grids experiencing two flash drought events and a development rate exceeding 15%. Moreover, the summer heat in 2022 was more extreme than in the other three years, extending from spring to fall, especially during July–August. Its evolution was driven by the Western Pacific Subtropical High, which suppressed precipitation and elevated temperatures. The divergence of water vapor flux intensified water shortages, while anomalies in latent and sensible heat fluxes increased surface evaporation and heat transfer, further disturbing the regional water cycle. This study provides valuable insights for flash drought monitoring and early warning in the context of a changing climate. Full article

Flash droughts, characterized by their abrupt onset and rapid intensification, are predicted to increase in frequency and severity under global warming. Understanding the incidence and progression of a flash drought and its impact on maize growth is crucial for maize production to withstand flash drought events. This study used the evaporative demand drought index (EDDI) method to evaluate the incidence of summer drought in Liaoning during the period 1961–2020. It examined the incidence and characteristics of summer flash droughts in Liaoning Province in the period of 1961–2020 and evaluated the factors responsible and the impact on maize during the critical development period. The ratio of the number of stations recording a disaster to total number of stations (IOC) curve, i.e., the ratio of the number of stations recording disasters and total stations, for summer flash droughts in Liaoning showed an upward trend during the period of 1961–2020, with large-scale, regional, and local flash droughts occurring in 8, 10, and 31 years, respectively. Summer flash droughts in Liaoning were mainly in the extreme drought category and ranged in frequency from 10% to 20% in most areas. Before the flash drought occurrence in three typical years (1989, 1997, and 2018), a precipitation deficit without large-scale high-temperature events was observed, and the cumulative water deficit caused the flash drought. Regional or large-scale high-temperature events were often accompanied by flash droughts, and the drought intensified rapidly, owing to the influence of heat waves and water deficits. Summer flash droughts caused a reduction in total primary productivity (GPP) of maize by more than 20% in most areas in the three typical years. The yield reduction rate in 1989, 1997, and 2018, was 27.6%, 26.4%, and 5%, respectively. The degree of decline in maize productivity and yield was associated with the onset and duration of the flash drought. The atmospheric conditions of summer flash droughts were characterized by high-pressure anomalies and atmospheric subsidence, which were unconducive for precipitation but conducive to flash drought occurrence. The continuous high-pressure anomaly promoted the maintenance of the flash drought. Full article

Flash drought is characterized by rapid onset and short-duration drought conditions caused by a combination of factors, including high evaporation, high temperature, and prolonged periods of little to no precipitation, leading to a sudden and severe decrease in soil moisture levels. In comparison to conventional drought, it is more susceptible to the effects of global warming and has the potential to become a common drought phenomenon in the coming years, necessitating further research. In this paper, we focused on flash drought events, specifically in forest parts of northeastern China that are included within the Greater Khingan Mountains (GKM), Lesser Khingan Mountains (LKM), and Changbai Mountains (CM), using daily soil moisture data as well as SPOT- VEGETATION NDVI satellite data from 2000 to 2020 and determined their impact on the forest NDVI. Our major findings are as follows. (1) The forest within GKM had the maximum area being affected by flash drought events. (2) The frequency ranged from 1 to 2 times, whereas the total duration varied between 20 and 55 days over the study area in a 21-year period. (3) Flash drought was most common in the plant-growing seasons. (4) The flash drought events had a negative influence on the forest NDVI. Our study contributes to a deeper understanding of the flash drought dynamics in forest areas of northeast China for flash drought monitoring, prediction, and management strategies in this region. Full article

Rice cultivation in the low-lying basin-like wetlands, known as the Haor, is often affected by early flash floods during the first two weeks of April. The flooding is mainly caused by heavy rainfall and water surging downstream from the Meghalaya hills in India. This flash flood poses a significant threat to rice production, risking the country’s food security. Dry winter (Boro) rice is the primary food source throughout the year in the Haor region. Flash floods are the most catastrophic, affecting about 80% or even the entire rice yield. In 2017, a loss of 0.88 million metric tons of Boro rice in Haor regions cost the nation USD 450 million. To escape flash floods, it is recommended to sow Boro rice earlier, between the last week of October and the first week of November, instead of around 15 November so rice may be harvested by the last week of March before the onset of flash floods. However, early sowing has a possibility of causing grain sterility due to cold spells when the booting and heading stages of rice inevitably coincide with the cold period between 15 January and 7 February. The minimum temperature in the Haor regions ranges from 11 to 15 °C during this time. Rice is especially susceptible to low average temperatures (<20 °C) during the reproductive stage, leading to pollen abortion and the malformation of immature microspores. Low temperatures mainly impact rice cultivation in Haor regions during the reproductive phase, resulting in the degeneration of the spikelets, partial panicle exertion, and increased spikelet sterility, leading to a decrease in grain yield. Over two million hectares of Boro rice have been damaged by extreme cold spells in recent years, resulting in partial or total yield loss. To overcome the threats of flash floods and cold injury, breeding short-duration and cold-tolerant rice varieties is crucial. We assume that an economic benefit of USD 230 million per year could be achieved through the development and adoption of short-duration and cold-tolerant high-yielding rice varieties in the Haor regions of the country. In this review article, the authors summarized the problems and outline a way forward to overcome the flash flood and cold injury of Boro rice cultivation in the Haor districts of the country. Furthermore, the authors discussed the various forms and scenarios of cold damage and the global existence of cold-tolerant rice cultivars. Based on the available data from earlier research, a potential way of mitigating flash floods and cold devastation was suggested. Full article

Lig-FC is a network depolymerization mechanism for the rapid primary devolatilization of mineral-free lignins that has already been validated with test data on 16 lignin samples. This paper expands the validation with an additional 13 lignins, including cases that applied different lignin preparations to the same feedstock. The validations reported here cover 27 mineral-free lignins for temperatures to 1150 °C, heating rates from 30 to 8000 °C/s, contact times after heatup to 90 s, and pressures from vacuum to 0.13 MPa. Lig-FC accurately depicts the impacts of lignin quality, heating rate, temperature, contact time, and pressure on the major products and oils’ molecular weight distributions (MWDs). All raw lignins contain abundant oil precursors that are released as oils via flash distillation as soon as a flow of noncondensables carries them into the free stream. Consequently, lignin MWD is an essential aspect of lignin constitution because it determines the inventory of inherent volatile chains subject to unhindered flash distillation. Lighter lignin MWDs have larger inherent inventories and therefore produce more oils than heavier MWDs at the onset of devolatilization. Oil yields diminish and char yields increase for progressively heavier MWDs and heavier mean monomer weights and for lignins with relatively less H and more O compared to C. Full article

The rapid intensification of drought, commonly known as flash drought, has recently drawn widespread attention from researchers. However, how the characteristics and drivers, as well as the ecological impacts of rapidly intensified droughts, differ from those of slowly intensified ones still remains unclear over the globe. To this end, we defined three types of droughts based on the root zone soil moisture (RZSM) decline rates, flash droughts, general droughts, and creep droughts, and then implemented a comparative analysis between them across the globe and the 26 Intergovernmental Panel on Climate Change Special Report on Extremes (IPCC-SREX) regions. The ensemble of RZSM from multiple reanalysis datasets was used to reduce the uncertainties. According to the frequency analysis, our findings suggest that flash droughts contributed to the majority of drought events during 1980–2019, indicating the prevalence of rapid transition from an energy-limited to a water-limited condition in most of the regions. The comparative results of vegetation responses show that flash droughts are more likely to happen in the growing season, leading to faster but relatively minor vegetation deterioration compared to the slowly intensified ones. By analyzing the precipitation and temperature anomalies in the month of drought onset, we found the role of temperature (precipitation) on drought intensification can be generalized as the warmer (drier) the climate is or the faster the drought intensifies, but the main driving forces vary by region. Unlike temperature dominating in midwestern Eurasia and northern high latitudes, precipitation plays a prominent role in the monsoon regions. However, the temperature is expected to be the decisive driver in the warming future, given its monotonically increased contribution over the past four decades. Full article

As crystallization behavior has a great effect on the injection molding process, the flash differential scanning calorimetry (FSC) method was employed to study the influence of cooling rate on the crystallization behavior of a semi-crystalline polypropylene (PP). As the experimental results show, crystallization temperatures (onset crystallization temperature and maximum crystallization temperature) and crystallinity decrease as the cooling rate increases. In addition, the corresponding mathematical models were established to describe the relationship between the crystallization temperatures/crystallinity and the cooling rate. A revised Tait equation was also carried out based on the mathematical models. Full article

When heat and electric field are applied to the sample, sintering takes place within a short time of a few seconds by the flash phenomenon that occurs. In what condition flash does occur is a main issue for the flash sintering technique. In this study, the effect of processing conditions such as sintering atmosphere, sample size, density and grain size on the flash onset of hydroxyapatite was investigated. In a vacuum atmosphere, a flash occurred at a lower temperature by 50–100 °C than in air. The smaller the thickness of the sample, the higher the flash onset temperature due to the larger specific surface area. Flash was also observed in samples which were presintered, having a density of 86–100% and a grain size of 0.2–0.9 μm. When the density and grain size of the sample were higher and larger, the flash onset temperature was higher. It was because the diffusion and conduction path through the grain boundary and the inner surface of the pores with high defect concentration are blocked with an increase of density or grain size. When an electric field was applied during flash sintering, a color change of the sample was observed and the reason was discussed. Full article

The need for sustainable solutions to reduce the carbon footprint of the ceramics and glass industry leads towards the development of new electric current-assisted technologies. Flash sintering-like processes in glasses allow a reduction of the softening temperature and could pave the way for new shaping technologies. Herein, we investigated the flash transition in soda-lime silicate glass using two different electrode materials, silver, and platinum. The high dielectric strength registered on samples tested with platinum electrodes undergoes a significant reduction when silver is used. In other words, in the case of silver electrodes, the flash ignition takes place at a lower onset field. Moreover, the Joule heating developed during the process can be turned from being highly inhomogeneous with Pt electrodes to homogeneous when Ag electrodes are used. Full article

Flash drought is a type of drought that develops quickly (usually within 2–4 weeks) in contrast to conventional, slowly evolving drought. Due to its sudden onset, flash drought is more difficult to predict and can cause major agricultural losses if it is not forecasted in a timely manner. To improve our ability to predict flash drought, we develop a subseasonal tool to predict areas susceptible to flash drought development using the Phase 2 of the North American Land Data Assimilation System (NLDAS-2) data. The tool calculates the rapid change index (RCI) using 7-day mean evapotranspiration anomalies. RCI is the accumulated magnitude of moisture stress changes (standardized differences) occurring over multiple weeks, and drought is likely to develop when RCI is negative. Since RCI changes with time, like all drought variables, it is difficult to capture drought development signals by monitoring RCI maps. In order to create an intuitive drought prediction map that directly depicts drought tendency, we use a threshold method to identify grid points with large decreases of 7-day mean evapotranspiration anomaly (i.e., RCI less than −0.5) in the last 30 days and under the condition that 3-month standardized precipitation index is less than −0.4. The real-time tool started running on 1 April 2018 at the NOAA Climate Prediction Center (CPC) and has been used to support CPC’s Monthly Drought Outlook efforts. The performance of the tool is evaluated using both retrospective and real-time predictions. The assessment shows promising results in predicting potential flash drought development, and the interplay between precipitation and high temperatures appears to be a challenge for flash drought prediction. Full article

Flash Joule-heating was applied to the Cu_47.5Zr_47.5Al₅ metallic glass for designing fully crystalline metastable nanocomposites consisting of the metastable B2 CuZr and low-temperature equilibrium Cu₁₀Zr₇ phases. The onset of crystallization was in situ controlled by monitoring resistivity changes in the samples. The effect of heating rate and annealing time on the volume fraction of the crystalline phases and mechanical properties of the nanocomposites was studied in detail. Particularly, an increase of the heating rate and a decrease of the annealing time lead to a lower number of equilibrium Cu₁₀Zr₇ precipitates and an increase of tensile ductility. Tailoring of these non-equilibrium microstructures and mechanical properties may not be possible unless one starts with a fully glassy material that opens new perspectives for designing metastable nanomaterials with unique physical properties. Full article