Long-term Trends Research Articles

Long-term trends in total administered radiation dose from brain [18F]FDG-PET in children with drug-resistant epilepsy.

To assess the trends in administered 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) doses, computed tomography (CT) radiation doses, and image quality over the last 15years in children with drug-resistant epilepsy (DRE) undergoing hybrid positron emission tomography (PET) brain scans. We retrospectively analyzed data from children with DRE who had [18F]FDG-PET/CT or magnetic resonance scans for presurgical evaluation between 2005 and 2021. We evaluated changes in injected [18F]FDG doses, administered activity per body weight, CT dose index volume (CTDIvol), and dose length product (DLP). PET image quality was assessed visually by four trained raters. Conversely, CT image quality was measured using region-of-interest analysis, normalized by signal-to-noise (SNR) and contrast-to-noise ratio (CNR). We included 55 children (30 male, mean age: 9 ± 6years) who underwent 61 [18F]FDG-PET scans (71% as PET/CT). Annually, the injected [18F]FDG dose decreased by ~ 1% (95% CI: 0.92%-0.98%, p < 0.001), with no significant changes in administered activity per body weight (p = 0.51). CTDIvol and DLP decreased annually by 16% (95% CI: 9%-23%) and 15% (95% CI: 8%-21%, both p < 0.001), respectively. PET image quality improved by 9% year-over-year (95% CI: 6%-13%, p < 0.001), while CT-associated SNR and CNR decreased annually by 7% (95% CI: 3%-11%, p = 0.001) and 6% (95% CI: 2%-10%, p = 0.008), respectively. Our findings indicate stability in [18F]FDG administered activity per body weight alongside improvements in PET image quality. Conversely, CT-associated radiation doses reduced. These results reaffirm [18F]FDG-PET as an increasingly safer and higher-resolution auxiliary imaging modality for children with DRE. These improvements, driven by technological advancements, may enhance the diagnostic precision and patient outcomes in pediatric epilepsy surgery.

The first satellite measurements of HFC-125 by the ACE-FTS: Long-term trends and distribution in the Earth’s upper troposphere and lower stratosphere

HFC-125 (CF3CHF2, pentafluoroethane) volume mixing ratios (VMRs) have been determined for the first time using infrared absorption spectra from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) from 2004 to 2024. These VMRs provide global altitude-latitude VMR distributions. A VMR time series for HFC-125 has also been calculated and compared to values from in situ discrete flask measurements conducted by the National Oceanic and Atmospheric Administration Earth System Research Laboratory. The abundance of HFC-125 is currently experiencing exponential growth. ACE data shows a growth rate of 3.47 ± 0.05 ppt/year in the past six years.

The Accelerating Loss of Resilience in Suburban Woodlands Can Largely Be Attributed to the Changes in Urban Precipitation Patterns.

Vegetation resilience holds significant importance for stabilizing ecosystem service functions in a changing climate. While global land surface vegetation resilience changes have been extensively studied, the impact of urbanization on the resilience of suburban woodlands remains inadequately understood. In this study, we utilized two critical slowing down (CSD) indicators, namely lag-one autocorrelation (LOA) and variance (VA), to assess the vegetation resilience, its long-term trends, and influencing factors in suburban woodlands across 1356 cities worldwide. The recovery rates estimated by LOA ( ) and VA ( ) showed close alignment in suburban woodlands with low suburban forest coverage (SFC) areas (correlation coefficient (r) = 0.95). However, a notable divergence was observed in areas with high SFC (r = 0.73). Suburban woodlands with high SFC typically exhibited lower recovery rate estimates, thus indicating greater vegetation resilience compared to areas with lower SFC. From 1986 to 2022, the recovery rates of suburban woodland areas in over 83% of the cities demonstrated a significant upward trend, with an average of 3.23 × 10-3 year-1 for both and , signifying a widespread decline in vegetation resilience. The accelerating pace of urbanization led to higher rising rates of and during 2010-2022 (5.11 × 10-3 year-1) compared to 1986-1999 (0.49 × 10-3 year-1). The notable decrease in resilience of forestland was primarily attributed to reduced precipitation in urban suburbs, which can be explained by urbanization-induced heat island and building barrier effects, causing a shift of precipitation center from urban suburbs to central cities. In summary, this study revealed that urbanization diminishes the vegetation resilience of urban suburban woodlands by altering urban precipitation patterns. These findings underscore the necessity of augmenting water availability in urban suburbs to restore resilience in these woodlands, thereby enhancing their ecosystem service value.

Multiscale investigations on RDI-SPI teleconnections of Çoruh and Aras Basins, Türkiye using Time Dependent Intrinsic Correlation

This paper proposes a multiscale dynamic correlation framework based on time-dependent intrinsic correlation (TDIC) to investigate the teleconnections between reconnaissance drought index (RDI) and standardized precipitation index (SPI). The SPI and RDI indices were calculated at 3-, 6-, and 12-month time scales using data from six stations in the Çoruh and Aras (CA) basins in Turkey for the 1969 - 2020 period. The spatial variability of the evaluation of the drought class demonstrated that, with the exception of the northwestern region (Bayburt station), the correlation between RDI and SPI exceeded 97% and the difference in occurrence between drought classes is found to be marginal. In the multiscale analysis of the two indices, firstly, the Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (I-CEEMDAN) was employed to decompose the series. The modes of RDI and SPI at different process scales exhibited a strong positive linear correlation, however, the association in their long-term trends may not be of the same nature. The TDIC analysis captured the long-range correlations between the modes of RDI and SPI at diverse process scales, and the newly proposed average significant correlation (ASC) measure could quantify their strength. Within the basin, there exists strong interconnections between SPI and RDI, with the exception of the observed alterations in their nature and strength at short time spells in some inter-annual scales. The proposed TDIC based framework is a generic and robust alternative for multiscale investigation studies while ASC can quantify the strength of non-linear associations at distinct process scales.

Long-term Trends In Step Counts Among Non-working Adults: National Health And Nutrition Survey Japan 2001-2019

Long-term Trends In Step Counts Among Non-working Adults: National Health And Nutrition Survey Japan 2001-2019

Development of over 30-years of high spatiotemporal resolution air pollution models and surfaces for California

California’s diverse geography and meteorological conditions necessitate models capturing fine-grained patterns of air pollution distribution. This study presents the development of high-resolution (100 m) daily land use regression (LUR) models spanning 1989–2021 for nitrogen dioxide (NO2), fine particulate matter (PM2.5), and ozone (O3) across California. These machine learning LUR algorithms integrated comprehensive data sources, including traffic, land use, land cover, meteorological conditions, vegetation dynamics, and satellite data. The modeling process incorporated historical air quality observations utilizing continuous regulatory, fixed site saturation, and Google Streetcar mobile monitoring data. The model performance (adjusted R2) for NO2, PM2.5, and O3 was 84 %, 65 %, and 92 %, respectively.Over the years, NO2 concentrations showed a consistent decline, attributed to regulatory efforts and reduced human activities on weekends. Traffic density and weather conditions significantly influenced NO2 levels. PM2.5 concentrations also decreased over time, influenced by aerosol optical depth (AOD), traffic density, weather, and land use patterns, such as developed open spaces and vegetation. Industrial activities and residential areas contributed to higher PM2.5 concentrations. O3 concentrations exhibited no significant annual trend, with higher levels observed on weekends and lower levels associated with traffic density due to the scavenger effect. Weather conditions and land use, such as commercial areas and water bodies, influenced O3 concentrations.To extend the prediction of daily NO2, PM2.5, and O3 to 1989, models were developed for predictors such as daily road traffic, normalized difference vegetation index (NDVI), Ozone Monitoring Instrument (OMI)–NO2, monthly AOD, and OMI-O3. These models enabled effective estimation for any period with known daily weather conditions.Longitudinal analysis revealed a consistent NO2 decline, regulatory-driven PM2.5 decreases countered by wildfire impacts, and spatially variable O3 concentrations with no long-term trend. This study enhances understanding of air pollution trends, aiding in identifying lifetime exposure for statewide populations and supporting informed policy decisions and environmental justice advocacy.

Long-term outcomes and trends in elbow arthroplasty with Coonrad-Morrey prosthesis: a retrospective study in large group of patients.

Total Elbow Arthroplasty (TEA) was first developed to treat severe rheumatoid arthritis, but its uses have grown to encompass end-stage osteoarthritis, post-traumatic arthritis, and distal humeral fractures. This study analyzes indications changes, long-term survival, complications, and post-operative functional results of the Coonrad-Morrey prostheses, enhancing the existing literature on this technique and substantial case history. We included 122 arthroplasties in 117 patients, 28 males and 89 females (mean age of 67 years) treated in our hospital between 2002 and 2016. Minimum follow-up was four years. We collect functional parameters of 48 patients (51 elbows), due to death of patients due to old age and loss at follow-up. Survival rate at five years was 90%, 85% at 10 years and 83% at 15 years. The overall medium Mayo elbow score was 79.7 ± 18.3 with the highest result in osteoarthritis patients (p < 0.005); QuickDASH score was 33.1 ± 25.5 with the worse result in rheumatoid group. Average post-operative arc of motion (ROM) was 95°±27°. There were complications in 46 out of 122 cases (37.7%) and revision surgeries were performed in 12 of them (9.8%): seven aseptic loosening, four late septic loosening, one bushing wear. In 27 instances (22.1%) was reported ulnar nerve involvement. Coonrad-Morrey prosthesis has shown satisfactory clinical results in the treatment of a wide range of pathologies. The long-term implant survivorship was satisfactory, yet the occurrence of failures and complications cannot be overlooked, above all the ulnar nerve paresthesia. There was a good recovery in quality of life, pain-free with limited residual limb disability.

Independent Media, Propaganda, and Religiosity: Evidence from Poland

Exploring a drastic change in media landscape in Poland, we show that mainstream media can significantly affect religious participation. After nationalist populist party PiS came to power in 2015, news on state and private independent TV diverged due to propaganda on state TV, resulting in a switch of some of its audience to independent TV. Municipalities with access to independent TV continued to follow a long-term secularization trend, while municipalities with access only to state TV experienced a reversal of this trend. An online experiment sheds light on the mechanisms underlying the effect of exposure to independent news on religiosity. (JEL D12, D83, L82, Z12)

Cross-sectional study of assessment of lung cancer (LC) screening awareness in an underserved community in the Bronx, New York.

155 Background: LC remains the second most diagnosed cancer but is the leading cause of cancer death in the USA, accounting for 21% of all cancer deaths. Despite advances in screening and treatment, it remains the principal cause of cancer mortality worldwide. Notably, survival rates have improved from 21% to 25% over the past 5 years. However, LC screening with low-dose computed tomography (LDCT) is underutilized, with only 5.8% of eligible individuals screened in 2021. Methods: A prospective 29-question survey was conducted at St. Barnabas Health Care System in the Bronx, NY, from February to April 2024. The survey included patients aged 50-80, both former and active smokers. Data on demographics, social determinants, and knowledge of LC and LDCT screening were collected and processed using JASP Version 0.18.3. The study aimed to assess the community's knowledge of lung cancer screening, with demographic characteristics as secondary outcomes. Results: From all the surveys collected, 115 met the inclusion criteria, 53% male (61) and 47% female (54), with no significant difference between proportions (p=0.576). The median age was 63 years. Race: 73% were Hispanic, 22% Black, and 5% White, with significant differences from an equal distribution (p&lt; 0.001). Legal Status, citizens (74%), followed by green card holders (17%). Most of the patients lived in the USA for over 20 years (90%), with very few having lived for less than five years (1%), indicating a long-term residency trend (p &lt; 0.001). Education Level: high school education was the most common (58%), followed by middle school (17%) and elementary school (15%). Doctorate and graduate degrees were less common (7%). 91% of patients were aware of the relationship between cigarette smoking and LC, while 9% did not (p&lt;0.001). On the other hand, 66% believed there was a relationship between e-cigarette use and LC, while 44% believed there was not. Patients with an income greater than $50,000 have significantly more knowledge of the screening tool for LC (STLC), as indicated by a Chi-square value of 50.87 (p &lt; 0.05, with a critical value of 5.99). Patients with low education levels have less knowledge of the existing STLC, with a Chi-square of 143.587 (p&lt;0.05 and a critical value of 9.488). Conclusions: Our study highlights critical disparities in LC awareness and knowledge of screening tools among different demographic groups. There is a clear need for targeted educational initiatives, especially for lower-income and less-educated populations, to improve understanding of LC risks associated with both traditional and electronic cigarette use. The significant presence of long-term Hispanic residents suggests that culturally tailored interventions could be particularly effective. Addressing these gaps is essential for enhancing lung cancer prevention and early detection efforts across diverse communities.

Climate change stands as the new challenge for whale watching and North Pacific gray whales (Eschrichtius robustus) in Bahia Magdalena, Mexico, after their recovery from overexploitation

IntroductionSocial-ecological systems (SES) recognize the intricate relationship between human activities and the environment and advocate for comprehensive approaches to address complex environmental issues. This study investigates the factors influencing whale watching, particularly the gray whale (Eschrichtius robustus) in northern Mexico, after significant recovery following overexploitation. Despite reaching a peak in 2015, the eastern North Pacific gray whales experienced unusual mortality events (UME), the most recent from 2019 to 2023, leading to a population decline and historically low calf production in 2022. This decline is evident in the reduced presence of whales and calves in winter breeding lagoons. Concurrently, whale watching has become a significant tourist attraction in these areas.MethodsOur objective was to develop a mental model of the SES of gray whale watching, integrating ecological and socioeconomic data to identify key variables and interactions that support system resilience. From an ecological perspective, we analyzed the long-term temporal trends of eight years of gray whale counts in the southernmost breeding and nursing lagoons within the Bahía Magdalena–Bahía Almejas Complex, Mexico. Additionally, we incorporated the current discussion in the literature about the potential impact of global climate change on gray whale populations. In the socioeconomic subsystem, we used participatory methods, including interviews, surveys, and workshops with government officials, tourism operators, and visitors. We also added on-site assessments of compliance with welfare regulations to understand tourism dynamics. ResultsOur findings identified as main external stressors the changes in ice levels in feeding areas and sea warming in breeding areas, and as internal stressors the compliance with official regulations and the number of vessels observing whales at the same time. The key socioeconomic factor of the system was tourist satisfaction, influenced by factors such as the quality of the information provided by operators. DiscussionUltimately, our mental model provides a framework for further exploration of relevant interactions and trajectories, offering insights for developing effective management strategies.

Trends in malignant neoplasm of bone and articular cartilage related mortality among older adults in United States (1999 to 2020)

Introduction: Malignant neoplasms of bone and articular cartilage, although rare, are associated with substantial morbidity and mortality, posing a serious health burden. Understanding the trends in mortality related to these cancers is crucial for developing targeted interventions and improving patient outcomes. This study aims to analyze long-term mortality trends, identify demographic and geographic disparities, and uncover potential factors driving changes in mortality rates. Methods: This retrospective study analyzed mortality rates among individuals aged 65 and older from 1999 to 2020 using CDC WONDER death certificate data, abstracting demographics, geographic factors, and urban/rural status. Results: From 1999 to 2020, 18,205 adults aged 65 and older died from malignant neoplasms of bone and cartilage. The age-adjusted mortality rate (AAMR) started at 20 per 100,000 in 1999 and steadily declined until 2012 (APC: -1.12). However, from 2012 onwards, there was a notable reversal, with the AAMR rising sharply to 23.8 by 2020 (APC: 4.73). Men had higher mortality rates than women, with NH Black individuals showing the highest rates among races. Southern states and non-metropolitan areas had elevated AAMRs, suggesting targeted interventions for better outcomes and lower death rates. Conclusion: The findings highlight significant inequities, with Southern states and non-metropolitan areas showing elevated age-adjusted mortality rates (AAMRs). These geographic disparities underscore the urgent need for targeted public health interventions in these regions to improve cancer outcomes and reduce mortality. Addressing these gaps is essential for achieving more equitable health outcomes, particularly in high-risk populations.

Fingerprints of El Niño Southern Oscillation on global and regional oceanic chlorophyll-a timeseries (1997–2022)

With the advancement of present-day ocean color satellites, the spatiotemporal variations of oceanic Chlorophyll-a (Chl-a) concentration, a proxy for phytoplankton population, can be monitored at regional and global scales. Estimating long-term changes in Chl-a concentration, however, is mainly constrained by the limited availability of ocean color data and the significant influence of climate oscillations like the El Niño Southern Oscillation (ENSO). In this study, we investigate the influence of ENSO on regional and global Chl-a timeseries using two ocean color datasets spanning from September 1997 to December 2022. Our analysis found that global Chl-a concentration exhibits a significant increasing trend over the study period. Most of the increasing trends are detected in the Southern Hemisphere (SH) and high-latitudinal regions, including the Southern Ocean. In light-limited regions like the Southern Ocean, enhanced Chl-a concentration shows a strong positive correlation with warming sea surface temperature (SST). Conversely, most oceans in the Northern Hemisphere (NH) exhibit decreasing trends, which are highly correlated with warming SST and ENSO phases. Additionally, we identify distinctive fingerprints of four extreme ENSO events: two extreme El Niño events (1997–1998 and 2015–2016) and two triple La Niña events (1998–2001 and 2020–2022) in these timeseries. Furthermore, empirical orthogonal function (EOF) analysis reveals that the dominant mode of interannual Chl-a variability is associated with an ENSO-like pattern, accounting for about 13 % of the total variability. Intriguingly, this principal mode is highly correlated with the phases of ENSO (R = -0.87) and Pacific Decadal Oscillation (PDO) (R = −0.90) on an interannual scale. This study provides insights into assessing the impacts of ENSO on long-term Chl-a trend estimation.

Long Term 5G Base Station Traffic Prediction Method Based on Spatial-Temporal Correlations

In the domain of 5G network management, accurately predicting traffic volumes at base stations remains a critical yet challenging endeavor, primarily due to the complexities inherent in the spatial and temporal data interactions. Current methods often fall short in effectively harnessing long-term trends and spatial interconnections among base stations. To bridge these gaps, this paper introduces the GCformer model, a novel approach that capitalizes on both spatial relationships and temporal patterns for multi-base station traffic prediction. Spatially, the proposed model employs graph convolutional networks to integrate diverse spatial information and construct insightful adjacency matrices that includes Euclidean distances and non-Euclidean distances (area types of base station locations and similarities in traffic flow among various stations), thereby enhancing the predictability of traffic dynamics. Temporally, the application of the Transformer's attention mechanism enables better capture of long-term relational dependencies in the temporal domain of 5G base station traffic data. Additionally, a time-variant optimization module is designed to establish diurnal cycle data for each base station's traffic, replacing the traditional positional encoding with a more nuanced model that improves the learning of historical data correlations. Empirical results from exhaustive case studies confirm the superiority of the GCformer model in forecasting traffic volumes. The GCformer exhibits a 4.01% improvement in mean squared error and a 3.37% enhancement in mean absolute error compared to the best-performing baseline model, showcasing its potential to significantly improve operational strategies in 5G networks.

Continuous Health Monitoring of Reinforced Concrete Bridge Deck based on Traffic Load-induced Acoustic Emission

This paper presents continuous bridge deck monitoring based on b-value obtained from traffic load-induced acoustic emission (AE) signals. Using the self powered AE system that we developed, we have observed traffic load-induced AE on an actual bridge for five years. The developed self-powered AE system demonstrated that long-term traffic load-induced AE measurements over five years could be performed without an external power source. Traffic load-induced AEs measured irregularly by event-driven measurement were accumulated, and b-values were calculated. We used an additive regression model that accounts for piecewise linear trends and seasonality to extract long-term trends accurately. Over the past five years, the bridge has deteriorated. In addition, repairs were made during the period. As a result of this monitoring, we determined the relationship between the damage condition of the bridge and the b-value trend obtained from the traffic load-induced AEs. The results confirmed that the b-value based on traffic load-induced AE corresponds well with the damage conditions on the underside of the deck slab or in a shallow area inside it.

Trends in Adolescent Depression Screening Outcomes Over the COVID-19 Pandemic at a Large, Integrated Health Care System in Southern California

PurposeLittle is known about changes in depression screening outcomes among adolescents in primary healthcare across the COVID-19 pandemic. We describe trends in depression screening outcomes within a large integrated health care system in Southern California. MethodsRetrospective electronic health record data from preventative healthcare visits of 11–12-year-olds and 13–17-year-olds screened for depression from March 1, 2017, to August 31, 2022, were extracted in 6-month blocks. The percentages of screens meeting “threshold depression” were reported overall, and by sex, race or ethnicity, and median household income quintiles. We used Poisson regression to estimate rate ratios of threshold depression in 3 winter blocks (September to February) comparing lockdown (2020), reopening (2021) to a pre-COVID (2019) period, and reopening relative to lockdown. Disparities in trends by sex, race, or ethnicity and household income were tested using interaction terms. ResultsOf 735,333 visits with complete screening (183,550 for 11–12-year-olds and 551,783 for 13–17-year-olds), 4.6%, 6.5%, and 7.4% of 11–12-year-olds had “threshold depression” during winter blocks of pre-COVID, lockdown and reopening, respectively. The corresponding rates were 5.8%, 8.5%, and 9.8% for 13–17-year-olds. The rates were higher during lockdown and reopening relative to pre-COVID and higher during reopening relative to lockdown for both age groups (all p-values <.001). Trends differed by sex in both age groups (p-values <.001) and by race or ethnicity (p = .001) in the 13–17-year age group. DiscussionCalifornian adolescents demonstrated an increase in threshold depression since COVID lockdown starting March 2020 with further increase observed during reopening in September 2021. Future studies are needed to determine the long-term trends.

Fluctuations and extreme events in the public attention on Italian legislative elections

The share of social media attention to political candidates was shown to be a good predictor of election outcomes in several studies. This attention to individual candidates fluctuates due to incoming daily news and sometimes reflects long-term trends. By analyzing Twitter data in the 2013 and 2022 election campaign we observe that, on short timescales, the dynamics can be effectively characterized by a mean-reverting diffusion process on a logarithmic scale. This implies that the response to news and the exchange of opinions on Twitter lead to attention fluctuations spanning orders of magnitudes. However, these fluctuations remain centered around certain average levels of popularity, which change slowly in contrast to the rapid daily and hourly variations driven by Twitter trends and news. In particular, on our 2013 data we are able to estimate the dominant timescale of fluctuations at around three hours. Finally, by considering the extreme data points in the tail of the attention variation distribution, we could identify critical events in the electoral campaign period and extract useful information from the flow of data.

A nonstationary stochastic simulator for clustered regional hydroclimatic extremes to characterize compound flood risk

Traditional approaches to flood risk management assume flood events follow an independent, identically distributed (i.i.d.) random process from which static risk measures are computed. Modern risk accounting strategies also consider nonstationarity or long-term trends in the mean and moments of the associated flood probability distributions. However, few approaches consider how extreme hydroclimatic events cluster in both space and time, compounding damage risks. Here we introduce a compound flood risk simulator that models and conditionally forecasts future variability in regional flooding events that cluster in time, given trends and oscillations in a variable climate signal. A modular, novel integration of wavelet signal processing, nonstationary time series forecasting, k-nearest neighbor (KNN) bootstrapping, multivariate copulas, and modified Neyman-Scott (NS) event clustering process provides users the ability to model interannual and sub-annual clustering of flood risk. Our semi-parametric flood generator specifically targets the clustered temporal dynamics of jointly modeled flood intensity, duration, and frequency over a finite future period of a decade or more, thereby providing a foundation for adaptation approaches that integrate temporally clustered flood risk into planning, response and recovery.

Health-safety inspection and organisational performance of female-owned enterprises in China.

This study examines the impact of health and safety inspections on the organizational performance of female-owned enterprises in China, utilizing data from the "Health Safety and Inspection - China - 2023" dataset. The research addresses three key objectives: assessing the prevalence and outcomes of health and safety inspections among female-owned firms, analysing the average performance and sales growth, and evaluating the performance differences between inspected and non-inspected firms. The study applied descriptive analysis comprising graphs. Findings reveal that a significant majority (94.5%) of female-owned firms undergo inspections, with over half receiving formal reports. The analysis shows variable short-term performance with an average annual sales figure of 31,600,000 Chinese yuan (¥), but a positive long-term growth trend of 3% over three years. Firms subjected to health and safety inspections demonstrate better performance compared to non-inspected counterparts, with increasingly pronounced benefits over time. The study concludes that health and safety inspections positively impact long-term organizational performance. We recommend policies for increasing the frequency and quality of inspections, providing targeted support for female entrepreneurs, and conducting longitudinal and sector-specific studies to further understand the sustained effects of inspections.

Climate and topography control variation in the tropical dry forest-rainforest ecotone.

Ecotones are the transition zones between ecosystems and can exhibit steep gradients in ecosystem properties controlling flows of energy and organisms between them. Ecotones are understood to be sensitive to climate and environmental changes, but the potential for spatiotemporal dynamics of ecotones to act as indicators of such changes is limited by methodological and logistical constraints. Here, we use a novel combination of satellite remote sensing and analyses of spatial synchrony to identify the tropical dry forest-rainforest ecotone in Area de Conservación Guanacaste, Costa Rica. We further examine how climate and topography influence the spatiotemporal dynamics of the ecotone, showing that ecotone is most prevalent at mid-elevations where the topography leads to moisture accumulation and that climatic moisture availability influences up and downslope interannual variation in ecotone location. We found some evidence for long-term (22 year) trends toward upslope or downslope ecotone shifts, but stronger evidence that regional climate mediates topographic controls on ecotone properties. Our findings suggest the ecotone boundary on the dry forest side may be less resilient to future precipitation reductions and that if drought frequency increases, ecotone reductions are more likely to occur along the dry forest boundary.

Characteristics of extreme hourly precipitation induced by tropical cyclones in Zhejiang, China: A comparative analysis based on two different datasets

This study investigates the characteristics of tropical cyclones (TCs) that cause extreme hourly precipitation (EXHP) in Zhejiang, China, using datasets from 67 national stations (Con-ST) and 1551 surface stations (All-ST), spanning 1973–2020 and 2011–2020, respectively. Our analysis revealed notable variations in the EXHP caused by individual TCs. The top 10 % of TCs contributed 37.2–38 % of the total TC-induced EXHP amount, while the bottom 50 % only accounted for 5.8–22.7 %. Using sparse stations may overestimate the impact of TCs causing EXHP in the lower to middle rankings. Long-term trend analysis suggested a consistent increase in TC-induced EXHP despite a decreasing trend in the number of TCs affecting Zhejiang. High-value EXHP centers tended to be concentrated in mountainous areas within 0–50 km from the coastline, where Con-ST stations are sparse and can significantly underestimate EXHP. The maximum amount of EXHP per TC increased logarithmically with the number of observation stations. In Zhejiang, EXHP predominantly occurred northeast of the TC centers (50.4–61.7 %) and within 500 km from the TC center (69.5–81.5 %). High-frequency EXHP centers exhibited a clockwise rotation with increasing distance from the TC center–a pattern resembling a “spiral rainband.” A key area where most EXHP in Zhejiang occurred when TC centers remained within this area was identified. The TC intensity within the key area was a key factor influencing EXHP occurrence in Zhejiang, whereas the duration of TC center residence within the key area and the distance of its movement were crucial predictors of significant EXHP occurrence. The analysis of large-scale environmental fields revealed that high-EXHP TCs are characterized by strong upper-level divergence, intense upward motion, and an expanded subtropical high. The southeasterly steering airflow drives these TCs northwestward, prolonging their impact on Zhejiang and resulting in significant moisture accumulation and EXHP.