Search Results (146)

Background: Arthropod-borne diseases primarily affect tropical and subtropical regions, exhibiting seasonal patterns that peak during hot and rainy months when conditions favor mosquito vector proliferation. Factors such as high temperatures, elevated humidity, rainfall, urbanization, and the abundance of natural and artificial breeding sites influence Aedes vector dynamics. In this context, arboviruses pose significant public health challenges, likely worsened by global warming. In Brazil, Aedes (Stegomyia) aegypti (Linnaeus, 1762) is the primary vector for yellow fever, dengue, chikungunya, and Zika. Aedes (Stegomyia) albopictus (Skuse, 1894) is an important global arbovirus vector and is considered a potential vector in Brazil. Entomological surveillance of these species often uses oviposition traps targeting immature stages. Evaluating studies that use ovitraps to collect Ae. aegypti and Ae. albopictus egg is essential for improving mosquito surveillance strategies. This study systematically reviewed peer-reviewed articles on ovitrap-based surveillance of Aedes mosquitoes in Brazil, published in Portuguese and English from 2012 to 2022. The findings suggest that ovitraps are an effective method for detecting the presence or absence of Ae. aegypti and Ae. albopictus, serving as a reliable proxy for estimating mosquito abundance in Brazilian contexts. Full article

Meiyu is a critical component of the summer rainy season over the Yangtze–Huaihe River Basin (YHRB) in China, and the Meiyu onset date (MOD), serving as a key indicator of Meiyu, has garnered substantial attention. This article demonstrates an in-phase relationship between MOD and the preceding spring Barents–Kara Seas ice concentration (BKSIC) during 1979–2023. Specifically, the loss of spring BKSIC promotes an earlier MOD. Further analysis indicates that decreased spring BKSIC reduces the reflection of shortwave radiation, thereby enhancing oceanic solar radiation absorption and warming sea surface temperature (SST) in spring. The warming SST persists into summer and induces significant deep warming in the BKS through enhanced upward longwave radiation. The BKS deep warming triggers a wave train propagating southeastward to the East Asia–Northwest Pacific region, leading to a strengthened East Asian Subtropical Jet and an intensified Western North Pacific Subtropical High in summer. Under these conditions, the transport of warm and humid airflows into the YHRB is enhanced, promoting convective instability through increased low-level warming and humidity, combined with enhanced wind shear, which jointly contribute to an earlier MOD. These results may advance the understanding of MOD variability and provide valuable information for disaster prevention and mitigation. Full article

Paleoenvironmental knowledge holds significant scientific value for elucidating the evolutionary history of Earth’s crust and for guiding the exploration of oil and gas resources. This study presents a comprehensive analysis of sporopollen–algae fossils from Well DW-2, located in the Zhu II Depression of the eastern South China Sea. The sampled strata of the well were from 0 to 3230 m in depth, with a substantial number of sporopollen–algae fossils identified within the Enping and Zhuhai Formations spanning from 2501 to 3227 m. Two distinct sporopollen–algae assemblages were delineated from bottom to top. The sporopollen characteristics reveal a transition from tropical and subtropical to subtropical and temperate plant communities, reflecting the warm and humid climate during the formation of the Enping Formation and the relatively cool and dry climate during the formation of the Zhuhai Formation. A significant number of marine dinoflagellate fossils were identified, and the observed changes in algal characteristics suggest that the Enping Formation was accumulated in a shallow marine environment, while the Zhuhai Formation was predominantly formed in a transitional setting between marine and terrestrial conditions at the shelf margin. These findings not only enhance our understanding of the paleoenvironmental conditions in the South China Sea region but also have broader implications for reconstructing global paleoclimates and identifying potential hydrocarbon reservoirs in similar sedimentary basins. Full article

This study examines the desiccation tolerance of Aedes aegypti and Aedes albopictus eggs, two major arbovirus vectors, in a subtropical region of Argentina to understand their survival under varying relative humidity (RH) conditions (35%, 68%, and 82%). Laboratory experiments revealed that Ae. aegypti eggs exhibited significantly higher survival rates across all RH levels and exposure times compared to Ae. albopictus. After 1 month, Ae. aegypti eggs maintained 88% survival at 35% RH, while Ae. albopictus survival dropped to 38%. This disparity was more pronounced at low RH, where Ae. albopictus eggs experienced a rapid decline in survival over time. The results highlight the importance of RH as a key factor influencing the persistence of both species in the environment. The coexistence of Ae. aegypti and Ae. albopictus in Puerto Iguazú suggests that microhabitats with distinct humidity conditions may favor one species over the other. These findings provide crucial insights for predicting mosquito population dynamics under changing climate conditions and developing more effective vector control strategies to reduce arbovirus transmission in subtropical regions. Full article

Against the backdrop of global warming, heatwaves in China have become more frequent, posing serious risks to public health and socio-economic stability. However, existing identification methods lack precision, and the driving mechanisms of heatwaves remain unclear. This study applies the Excess Heat Factor (EHF) to characterize heatwaves across China from 2013 to 2023, analyzing their spatiotemporal patterns and exploring key drivers such as atmospheric circulation and soil moisture. Key findings reveal significant regional differences: (1) Frequency and Duration—The southeastern coastal regions (e.g., the Yangtze River Delta) experience higher annual heatwave frequencies (1.75–3.5 events) but shorter durations (6.5–8.5 days). In contrast, the arid northwest has both frequent (1.5–3.5 events per year) and prolonged (8.5–14.5 days) heatwaves, while the Tibetan Plateau sees weaker and shorter events. (2) Driving Factors—Heatwaves in the Yangtze River Delta are primarily driven by an intensified subtropical high, leading to subsidence and clear-sky conditions. In Fujian, anomalous low-level winds enhance heat accumulation, while coastal areas show strong soil moisture–temperature coupling, where drier soils intensify warming. Conversely, soil moisture has a weaker influence on the Tibetan Plateau, suggesting a dominant atmospheric control. It is important to note that the EHF index used in this study does not directly account for humidity, which may limit its applicability in humid regions. Additionally, the ERA5 and ERA5-Land reanalysis data were not systematically validated against ground observations, introducing potential uncertainties. Full article

Urban heat islands (UHIs) constitute one of the most conspicuous anthropogenic impacts on local climates, characterized by elevated land surface temperatures in urban areas compared to surrounding rural regions. This study represents a novel and comprehensive effort to characterize the spectral signature of SUHI through the lens of the two-dimensional (2D) turbulence theory, with a particular focus on identifying energy cascade regimes and their climatic modulation. The theory of two-dimensional (2D) turbulence, first described by Kraichnan and Batchelor, predicts two distinct energy cascade regimes: an inverse energy cascade at larger scales (low wavenumbers) and a direct enstrophy cascade at smaller scales (high wavenumbers). These cascades can be detected and characterized through spatial power spectra analysis, offering a scale-dependent understanding of the SUHI phenomenon. Despite the theoretical appeal, empirical validation of the 2D turbulence hypothesis in urban thermal landscapes remains scarce. This study aims to fill this gap by analyzing the spatial power spectra of land surface temperatures across 14 cities representing diverse climatic zones, capturing varied urban morphologies, structures, and materials. We analyzed multi-decadal LST datasets to compute spatial power spectra across summer and winter seasons, identifying spectral breakpoints that separate large-scale energy retention from small-scale dissipative processes. The findings reveal systematic deviations from classical turbulence scaling laws, with spectral slopes before the breakpoint ranging from ~K^−1.6 to ~K^−2.7 in winter and ~K^−1.5 to ~K^−2.4 in summer, while post-breakpoint slopes steepened significantly to ~K^−3.5 to ~K^−4.6 in winter and ~K^−3.3 to ~K^−4.3 in summer. These deviations suggest that urban heat turbulence is modulated by anisotropic surface heterogeneities, mesoscale instabilities, and seasonally dependent energy dissipation mechanisms. Notably, desert and Mediterranean climates exhibited the most pronounced small-scale dissipation, whereas oceanic and humid subtropical cities showed more gradual spectral transitions, likely due to differences in moisture availability and convective mixing. These results underscore the necessity of incorporating turbulence theory into urban climate models to better capture the scale-dependent nature of urban heat exchange. The observed spectral breakpoints offer a diagnostic tool for identifying critical scales at which urban heat mitigation strategies—such as green infrastructure, optimized urban ventilation, and reflective materials—can be most effective. Furthermore, our findings highlight the importance of regional climatic context in shaping urban spectral energy distributions, necessitating climate-specific urban design interventions. By advancing our understanding of urban thermal turbulence, this research contributes to the broader discourse on sustainable urban development and resilience in a warming world. Full article

PM_2.5 pollution has intensified with rapid urbanization and industrialization, raising concerns about its health and environmental impacts. Both meteorological factors and urban forests play crucial roles in influencing PM_2.5 concentrations. However, limited attention has been given to the direct impact of canopy structure on PM_2.5 levels at a larger scale. This study analyzes the temporal variation of PM_2.5, including seasonal and diurnal patterns, across different functional zones (park, traffic, and residential zones) in a subtropical region. It also investigates the seasonal responses of PM_2.5 to meteorological factors (temperature, humidity, and precipitation) and canopy structure characteristics, including canopy diameter (CD), canopy thickness (CT), canopy area (CA), canopy volume (CV), canopy height ratio (CH), leaf area index (LAI), and tree canopy cover (CO). The results show that among different functional zones, PM_2.5 concentrations were the highest in park zones, followed by traffic zones. Seasonal variations in PM_2.5 concentrations were the highest in winter (84.00 ± 45.97 μg/m³), with greater fluctuations, and the lowest in summer (36.85 ± 17.63 μg/m³ µg/m³), with smaller fluctuations. Diurnal variation followed an “N”-shaped curve in spring, summer, and autumn, while a “W”-shaped curve was observed in winter. Correlation analysis indicated significant negative correlations between PM_2.5 and humidity, temperature, and rainfall, while CD, CA, and CV showed positive correlations with PM_2.5. Notably, PM_2.5 exhibited greater sensitivity to changes in canopy structure in winter, followed by autumn. Despite these findings, the influence of canopy structure on PM_2.5 concentrations was considerably smaller compared to meteorological factors. In particular, every 1 m² increase in canopy area could raise PM_2.5 levels by 0.864 μg/m³, whereas an average increase of 1 mm in rainfall could raise PM_2.5 by 13.665 μg/m³. These findings provide valuable guidance for implementing protective measures, improving air quality, optimizing urban greening strategies, and enhancing public health outcomes. Full article

The risk of forest diseases is on the rise due to climate change and the consequential increase in extreme weather events, which disrupt the balance between pathogen, hosts, and the environment. This study analyzed two consecutive outbreaks of canker disease in Betula alnoides (Buch.-Ham. ex D. Don 1825) plantations and the temperature and precipitation changes in 2019 and 2020 in the northern Guangdong Province, China, to understand the impact of meteorological factors on disease outbreaks. We also examined the growth and mortality of B. alnoides with different gap sizes and reserved densities to explore how stand structure affects disease resistance in B. alnoides individuals. In both years, the disease outbreaks were preceded by periods of increasing heat and significant drops in humidity, as indicated by the z-score and relative similarity index. The mortality of B. alnoides due to canker disease was negatively correlated with seedling growth, which was optimized at a moderate reserved density of 225–300 trees per hectare in the upper layer and a gap size of 500–750 m². The findings suggest that closely monitoring meteorological changes and implementing afforestation with a well-managed upper layer can help mitigate the impact of canker disease in subtropical regions, particularly in the context of climate change. Further long-term studies with a more systemic approach are needed to assess the effects of thinning and gap creation in forest management. Full article

In response to increasing global food demand and the significant water requirements of rice cultivation, this study aims to enhance water use efficiency in rice farming. Focusing on Jiayu County, a subtropical humid region in China, where rice is grown as a single crop every year, we investigated temporal variations in rice water requirements and the influence of effective rainfall on irrigation strategies. Data were collected from an experimental station within the Sanhulianjiang Reservoir in Jiayu County. Utilizing the Mann–Kendall trend test and the Seasonal–Trend Decomposition using the LOESS (STL) method, we analyzed historical data on rice water requirement (ET_c) and effective rainfall ($R_e$ ). Our findings reveal that annual water requirements for rice range between 432 mm and 746 mm, with peaks corresponding to critical growth stages such as tillering and jointing–booting. Effective rainfall contributes significantly to meeting these needs, providing 27–35% of the total water requirement during specific periods. Developed water-saving irrigation strategies, including optimized irrigation scheduling and the introduction of drought-resistant rice varieties, demonstrate a potential reduction in irrigation demands by approximately 33.84%. This study underscores the importance of integrating effective rainfall data into irrigation practices to enhance water use efficiency and promote sustainable rice production amidst climate variability challenges. Full article

This study evaluates the application of an expert opinion-based fuzzy method for reservoir operation in humid subtropical climate/hot-summer Mediterranean climatic classes (Cfa/Csa in the Köppen–Geiger climate classification system), which are characterized by humid subtropical to Mediterranean conditions with ample rainfall and seasonal water availability challenges. Effective reservoir management in these regions is critical for balancing water storage and downstream release and maintaining ecosystem health under variable hydrological conditions. The performance of the fuzzy method was compared to two meta-heuristic algorithms: gravitational search algorithm (GSA) and shuffled frog leaping algorithm (SFLA). System performance was assessed using key indices such as the reliability index as a measure of meeting water demands. The fuzzy method achieved the highest reliability index of 0.690, outperforming GSA (0.677) and SFLA (0.688), demonstrating its superior ability to ensure consistent water supply downstream. The fuzzy method, leveraging expert knowledge, not only enhanced downstream water supply reliability but also reduced computational time compared to the meta-heuristic approaches. The incorporation of expert opinions provides a practical, robust, and efficient framework for reservoir management in challenging climate conditions such as Cfa/Csa classes. Additionally, the fuzzy solution demonstrated superior adaptability to diverse hydrological conditions, balancing ecological and water supply needs effectively. These findings highlight the potential of using expert opinions to support sustainable reservoir operations by achieving optimal trade-offs between competing objectives and addressing challenges in water resource management under varying climatic conditions. Full article

This study presents a high-resolution palaeoclimate reconstruction based on a radiocarbon-dated 240 cm deep trench profile from Renuka Lake, Northwestern Himalaya, India. The palynological analysis provides insight into the palaeovegetation and palaeoclimatic dynamics of a subtropical, dense, mixed deciduous forest, predominantly characterized by Sal (Shorea robusta). The fossil pollen reveals the presence of tropical Sal mixed deciduous taxa, including Shorea robusta, Emblica officinalis, Murraya koenigii, Toona ciliata, Syzygium cumini, and Terminalia spp., which indicate that the region experiences a warm and humid climate with the strong Indian Summer Monsoon (ISM) during ~7500–4460 cal yr BP. Subsequently, Sal-mixed deciduous forests were replaced by highland taxa, viz., Pinus roxburghii and Abies pindrow, suggesting dry and cold conditions during ~4460–3480 cal yr BP. Additionally, warm and humid (~3480–3240, ~3060–2680, ~2480–2270 cal yr BP) and cold and dry conditions (~3240–3060, ~2680–2480, ~2270–1965 cal yr BP) recorded alternatively in this region. Improved ISM prevailed ~1965–940 cal yr BP, followed by cold and dry conditions ~940–540 cal yr BP. From ~540 cal yr BP to present, the appearance of moist deciduous taxa alongside dry deciduous and highland taxa in similar proportions suggests moderate climate conditions in the region. Environmental reconstructions are supported by the Earth System Palaeoclimate Simulation (ESPS) model, providing an independent validation of the pollen-based interpretations. This research contributes to our understanding of long-term vegetation dynamics in the Northwestern Himalaya and offers valuable insights into the historical variability of the Indian Summer Monsoon, establishing a foundation for future investigations of climate-driven vegetation changes in the region. Full article

The semi-humid evergreen broadleaved forest (SEBF) is the zonal vegetation type of western subtropical regions in China. Under human and natural disturbance, the area of SEBFs is severely shrinking, with remaining fragments scattered across mountains of the Central Yunnan Plateau. To explore the mechanisms of community assembly and species maintenance in the severely fragmented SEBFs, we selected three sites—Jinguangsi Provincial Nature Reserve, Huafoshan Scenic Area, and Qiongzhusi Forest Park—across the range of this vegetation type, and sampled a total of 42 plots of forest dominated by Castanopsis orthacantha Franch., the most widely distributed community type of SEBFs. We compared the species richness and composition of the communities of different age classes, employed the net relatedness index to characterize the phylogenetic structure of communities, and used Mantel tests and partial Mantel tests to quantify the impacts of spatial distance, age class, and habitat factors (including climate, topography, and soil) on species turnover across different spatial scales (i.e., intra- and inter-site) for trees, shrubs, and herbs, respectively. The results indicated the following: (1) In the young stage, the C. orthacantha communities exhibited a species richness statistically lower than those in middle-aged and mature communities. Notably, the difference in species richness among age classes was merely significant for shrub and herb species. Moreover, the phylogenetic structure changed towards over-dispersion with increasing community age. (2) The age class of the community played a pivotal role in determining taxonomic β diversity in the tree layer, while climate and soil factors significantly influenced β diversity in the shrub and herb layers of the communities. (3) Environmental filtering emerged as the predominant force shaping community assembly at the intra-site scale, whereas spatial distance was the primary determinant at the inter-site scale. Meanwhile, dispersal limitation versus biological interaction seemed to dominate the community dynamics of the C. orthacantha communities in the early versus middle and old ages, respectively. Our results highlight the variability in community assembly processes across different spatial and temporal scales, providing insights into the priority of the conservation and restoration of severely degraded zonal SEBFs. Expanding research to broader scales and other SEBF types, as well as considering the impacts of climate change and human activities, would provide further insights into understanding the mechanisms of community assembly and effective conservation strategies. Full article

Malaria, a climate-sensitive mosquito-borne disease, is widespread in tropical and subtropical regions, and its elimination is a global health priority. Malaria is endemic to Vanuatu, where elimination campaigns have been implemented with varied success. In this study, climate variables were assessed for their correlation with national malaria cases from 2014 to 2023 and used to develop a proof-of-concept model for estimating malaria incidence in Vanuatu. Maximum, minimum, and median temperatures; diurnal temperature variation; median temperature during the 18:00–21:00 mosquito biting period (VUT); median humidity; and precipitation (total and anomaly) were evaluated as predictors at different time lags. It was found that maximum temperature had the strongest correlation with malaria cases and produced the best-performing linear regression model, where malaria cases increased by approximately 43 cases for every degree (°C) increase in monthly maximum temperature. This aligns with similar findings from climate–malaria studies in the Southwest Pacific, where temperature tends to stimulate the development of both Anopheles farauti and Plasmodium vivax, increasing transmission probability. A Bayesian model using maximum temperature and total precipitation at a two-month time lag was more effective in predicting malaria incidence than using maximum temperature or precipitation alone. A Bayesian approach was preferred due to its flexibility with varied data types and prior information about malaria dynamics. This model for predicting malaria incidence in Vanuatu can be adapted to smaller regions or other malaria-affected areas, supporting malaria early warning and preparedness for climate-related health challenges. Full article

Coastal lagoons play an essential role in the energy balance and heat exchange to the atmosphere. Furthermore, at mesoscale Monsoon systems and at local scales, sea breeze influences surface processes; however, there is a lack of information on such processes in arid and semiarid regions. We aimed to characterize the atmospheric conditions during sea and land breeze in different seasons and analyze at different temporal scales the variation of atmospheric stability, turbulent fluxes, lifting condensation level, and atmospheric boundary layer height. The study site is a subtropical semiarid coastal lagoon, Estero El Soldado, located in Northwestern Mexico (27°57.248′ N, 110°58.350′ W). Measurements were performed from January 2019 to September 2020 with an Eddy Covariance system (EC) and micrometeorological instruments over the water surface. Results show that there is a strong seasonality that enhances sea–land breeze dominance; sea breeze was 83% more frequent during the Monsoon, and the land breeze was 55% more frequent in the Post-Monsoon. Specific humidity (23.32 ± 3.84 g kg⁻¹, q), potential temperature (307 ± 2.98 K, θ_p), latent heat (135 W m⁻², LE), and turbulent kinetic energy (0.81 m² s⁻², TKE) were significantly higher during the Monsoon season at sea breeze events. Atmospheric boundary layer (ABL) and lifting condensation level (LCL) were higher in the Pre-Monsoon season (3250 ± 71 m and 1142 ± 565 m, respectively). During the Monsoon, surface conditions lead to lower LCL (~800 m) due to the amount of water vapor (q = 23.3 g kg⁻¹). Full article

Dengue fever, caused by the dengue virus (DENV), poses a significant global health challenge, particularly in tropical and subtropical regions. Recent increases in indigenous DENV cases in Europe are concerning, reflecting rising incidence linked to climate change and the spread of Aedes albopictus mosquitoes. These vectors thrive under environmental conditions like temperature and humidity, which are increasingly influenced by climate change. Additionally, global travel accelerates the cross-border spread of mosquito-borne diseases. DENV manifests clinically in a spectrum from asymptomatic cases to severe conditions like dengue hemorrhagic fever and dengue shock syndrome, influenced by viral serotype and host factors. In 2024, Brazil experienced a fourfold increase in dengue cases compared to 2023, accompanied by higher mortality. Conventional control measures, such as vector control, community engagement, and vaccination, proved insufficient as climate change exacerbated mosquito proliferation, challenging containment efforts. In this regard, our review analyzes prevention measures and therapeutic protocols during the outbreak while addressing DENV transmission dynamics, clinical presentations, and epidemiological shifts. It also evaluates diagnostic strategies combining clinical assessment with serological and molecular testing, providing information to improve diagnostic and preventive measures. The global expansion of dengue-endemic regions, including outbreaks in Europe, highlights the urgent need for enhanced surveillance, proactive interventions, and international collaboration to mitigate the growing threat of Dengue and other arboviruses like West Nile, Zika, Chikungunya, Oropouche, and Yellow Fever viruses. Full article