Pronounced Seasonal Patterns Research Articles

Spatio-temporal evolution of land subsidence and susceptibility zonation of associated ground fissures in the urban area of loess plateau: a case in Xianyang city, China

For over 50 years, the Xianyang city on the Chinese loess plateau, has been deeply affected by land subsidence and its associated ground fissures. In this study, 67 Sentinel-1A images from 2015 to 2022 were analysed to obtain the spatio-temporal evolution of land subsidence. Subsidence centers identified in Yunyang town and Luqiao town exhibit annual subsidence rates of −31 mm/a and −26.7 mm/a, respectively, culminating in total subsidence of −258 mm in Yunyang town and −139 mm in Luqiao town. Moreover, time series analysis revealed that both towns exhibit pronounced seasonal subsidence patterns. It is believed that human cultivation and groundwater overuse, combined with the effects of active faults, have led to uneven land subsidence. Then, the gradient of land subsidence and its potential relation to ground fissure hazards were evaluated. The results highlight a strong spatial correlation between high subsidence gradient areas and dense ground fissure distribution. Therefore, we proposed for the first time to introduce the land subsidence gradient factors for the susceptibility mapping of ground fissures using the artificial neural network algorithm. The susceptibility zonation results show that integrating the gradient factor can improve the rationality of the susceptibility evaluation. The above understanding provides valuable support for disaster prevention and mitigation in urban areas affected by land subsidence and ground fissures in loess regions.

Into the wild: coupling otolith and archival tag records to test assumptions underpinning otolith chemistry applications in wild fish

Chronological records of elemental concentrations in fish otoliths are a widely used tool to infer the environmental conditions experienced by individual fish. To interpret elemental signals within the otolith, it is important to understand how both external and internal factors impact ion uptake, transport and incorporation. In this study, we have combined chronological records from otoliths and archival data storage tags to quantify the influence of internal (sex, size, age, growth) and external (temperature, depth, salinity) conditions on otolith elemental chemistry of cod (Gadus morhua) in natural settings of the Baltic Sea. This study focused on elements primarily under physiological control: Phosphorus (P), magnesium (Mg) and zinc (Zn); and elements under environmental control: Strontium (Sr), barium (Ba) and manganese (Mn). Based on known spatial and temporal patterns in environmental conditions and fish size, growth, and maturity, we posed a series of hypotheses of expected otolith element patterns. Partial effects of internal and external drivers on element concentration were analyzed using a Linear Mixed Model approach with random variables (fish and year). Predicted effects of otolith concentrations of all elements under physiological control (P, Mg, Zn) showed similar trends, with distinct seasonal patterns (lowest concentration in late spring, highest concentrations in winter), and a positive correlation with water temperature, in addition to higher Zn and lower P in spawning individuals. Predicted effects of otolith concentrations of elements expected to be predominantly under environmental control showed the predicted geographic and depth-related trends based on ambient salinity (Ba) and coastal hypoxia (Mn). However, contrary to expectation, Sr was unrelated to salinity. Predicted otolith Ba, Sr and Mn concentrations also exhibited pronounced seasonal patterns that were out of phase with each other but appeared to be partly explained by spawning/feeding migrations. While performing laboratory validation studies for adult fish is typically not possible, these results highlight the importance of assessing local water chemistry and freshwater endmembers in one’s study system before otolith elemental chemistry can be reliably used to reconstruct fish habitat use and environmental histories.

Snow-corrected vegetation indices for improved gross primary productivity assessment in North American evergreen forests

North American evergreen forests cover large areas and influence the global carbon cycle. Satellite remote sensing has been used to track the phenology of ecosystem photosynthesis of these forests by detecting variation in vegetation optical properties associated with physiological and structural features, and most of these methods have been closely tied to vegetation greenness. However, in evergreens, the application of satellite data to monitor photosynthetic phenology is often limited by the lack of sensitivity of greenness-based indices. In this study, we identified 47 evergreen forest flux sites in North America that had MODIS observation overlapping with the flux tower records. We then calculated four vegetation indices using MODIS MAIAC data (MCD19A1), including NDVI, CCI, NIRv, and kNDVI, for the 47 flux sites and evaluated relationships between gross primary productivity (GPP) and vegetation indices across the North American evergreen forests. Our results showed that snow had substantial effects on the performance of all vegetation indices in tracking GPP phenology, particularly in the early spring when rapid changes occurred to both GPP and snow cover. Different vegetation indices were affected differently, indicating contradictory and confounding effects of snow on these indices. After correcting for the snow effects, both CCI and NIRv performed well in tracking GPP phenology, albeit for different reasons. CCI is sensitive to seasonal changes in the relative levels of chlorophyll and carotenoid pigments, which are closely tied to GPP phenology in evergreens. NIRv is sensitive to the absorbed photosynthetically active radiation and to the contribution of deciduous components to the overall optical properties. We also found that correlations between GPP and vegetation indices varied among ecoregions and climate classes. In general, regions with pronounced seasonal GPP patterns had stronger correlations between GPP and greenness-based indices than regions with weaker seasonal GPP patterns. These biome differences were less pronounced for CCI. The snow artifacts and complementary vegetation index effects reported here should be considered in any large-scale studies of GPP using reflectance-based indices from optical satellites.

Behavioural patterns in zoo-housed Humboldt penguins (Spheniscus humboldti) revealed using long-term keeper-collected data: Validation of approaches and improved husbandry

Given the increasing obligation to elevate animal welfare beyond minimum expectations, zoos need robust mechanisms to monitor physical activity and species-appropriate behaviours. This is not without challenge as animal behaviour can vary seasonally or be influenced by external factors such as weather and visitors. In theory, keepers who work with animals year-round are ideally situated to collect behavioural data. However, time pressure often means any data collection is minimal, ad-hoc, or skewed towards particular times of day. Here we compare infrequent low-intensity ad-hoc data on activity and behaviour of zoo-housed Humboldt penguins (Spheniscus humboldti) collected by keepers with simultaneous high-intensity systematic data collected by a researcher. Once out-of-sight records (more frequent in researcher data) were excluded from both datasets, we found excellent agreement between keeper and researcher data. After this validation step, we collected extensive multi-year keeper data (diurnal hourly scan samples; 262 days across a 5-year study period) to assess potential influence of time of day, time of year, visitors, and weather on penguin behaviour. There were pronounced seasonal patterns: aquatic active behaviours were highest in autumn (38.9% in October) compared to early spring and late summer (February = 16.7%; August = 19.4%). Time of day was also important: terrestrial inactive behaviours increased throughout the day and this pattern was significantly more pronounced in summer than winter. Aquatic active behaviours were more frequent during warmer/sunnier conditions compared to cooler/wetter conditions, while the reverse was true for terrestrial inactive behaviours. Birds were much less active on days when the site was closed to visitors. Overall, we demonstrate that where keeper-collected data are validated and found to be robust and representative, there are real opportunities to study long-term behavioural patterns that can quickly translate to tangible husbandry benefits and improved animal welfare.

Consistent trajectories of rhinitis control and treatment in 16,177 weeks: The MASK-air® longitudinal study.

Data from mHealth apps can provide valuable information on rhinitis control and treatment patterns. However, in MASK-air®, these data have only been analyzed cross-sectionally, without considering the changes of symptoms over time. We analyzed data from MASK-air® longitudinally, clustering weeks according to reported rhinitis symptoms. We analyzed MASK-air® data, assessing the weeks for which patients had answered a rhinitis daily questionnaire on all 7 days. We firstly used k-means clustering algorithms for longitudinal data to define clusters of weeks according to the trajectories of reported daily rhinitis symptoms. Clustering was applied separately for weeks when medication was reported or not. We compared obtained clusters on symptoms and rhinitis medication patterns. We then used the latent class mixture model to assess the robustness of results. We analyzed 113,239 days (16,177 complete weeks) from 2590 patients (mean age ± SD=39.1 ± 13.7 years). The first clustering algorithm identified ten clusters among weeks with medication use: seven with low variability in rhinitis control during the week and three with highly-variable control. Clusters with poorly-controlled rhinitis displayed a higher frequency of rhinitis co-medication, a more frequent change of medication schemes and more pronounced seasonal patterns. Six clusters were identified in weeks when no rhinitis medication was used, displaying similar control patterns. The second clustering method provided similar results. Moreover, patients displayed consistent levels of rhinitis control, reporting several weeks with similar levels of control. We identified 16 patterns of weekly rhinitis control. Co-medication and medication change schemes were common in uncontrolled weeks, reinforcing the hypothesis that patients treat themselves according to their symptoms.

Bioturbation Intensity Modifies the Sediment Microbiome and Biochemistry and Supports Plant Growth in an Arid Mangrove System.

ABSTRACTIn intertidal systems, the type and role of interactions among sediment microorganisms, animals, plants and abiotic factors are complex and not well understood. Such interactions are known to promote nutrient provision and cycling, and their dynamics and relationships may be of particular importance in arid microtidal systems characterized by minimal nutrient input. Focusing on an arid mangrove ecosystem on the central Red Sea coast, we investigated the effect of crab bioturbation intensity (comparing natural and manipulated high levels of bioturbation intensity) on biogeochemistry and bacterial communities of mangrove sediments, and on growth performance of Avicennia marina, over a period of 16 months. Along with pronounced seasonal patterns with harsh summer conditions, in which high sediment salinity, sulfate and temperature, and absence of tidal flooding occur, sediment bacterial diversity and composition, sediment physicochemical conditions, and plant performance were significantly affected by crab bioturbation intensity. For instance, bioturbation intensity influenced components of nitrogen, carbon, and phosphate cycling, bacterial relative abundance (i.e., Bacteroidia, Proteobacteria and Rhodothermi) and their predicted functionality (i.e., chemoheterotrophy), likely resulting from enhanced metabolic activity of aerobic bacteria. The complex interactions among bacteria, animals, and sediment chemistry in this arid mangrove positively impact plant growth. We show that a comprehensive approach targeting multiple biological levels provides useful information on the ecological status of mangrove forests.IMPORTANCE Bioturbation is one of the most important processes that governs sediment biocenosis in intertidal systems. By facilitating oxygen penetration into anoxic layers, bioturbation alters the overall sediment biogeochemistry. Here, we investigate how high crab bioturbation intensity modifies the mangrove sediment bacterial community, which is the second largest component of mangrove sediment biomass and plays a significant role in major biogeochemical processes. We show that the increase in crab bioturbation intensity, by ameliorating the anoxic condition of mangrove sediment and promoting sediment bacterial diversity in favor of a beneficial bacterial microbiome, improves mangrove tree growth in arid environments. These findings have significant implications because they show how crabs, by farming the mangrove sediment, can enhance the overall capacity of the system to sustain mangrove growth, fighting climate change.

Habitat and weather influence body condition in white‐tailed deer, Wisconsin, USA

AbstractIn temperate and northern ecosystems where there are pronounced seasonal patterns in weather and available energy, there are corresponding patterns of body condition among white‐tailed deer (Odocoileus virginianus). Body condition of white‐tailed deer can affect survival and reproduction, which has large repercussions for state‐level natural resource agencies that allocate hunting permits. In this study, we investigated how variation in winter weather, spring phenology, habitat composition, and browse quantity affected white‐tailed deer body condition across a large spatial scale. Several body condition indicators (e.g., carcass mass, heart fat, antler size) were measured by hunters for 795 deer during September–December 2016–2018 in Wisconsin, USA. Winter severity in the previous year was an unreliable predictor of fall body condition of deer when winters were considered mild or moderate. The timing of spring green‐up had a consistent effect on the body condition of all age and sex classes of deer. Earlier spring green‐up resulted in heavier fawns and larger antlers among adult males. Region and spring green‐up interacted to affect the heart fat of adult females. Earlier springs resulted in adult females in northern and central Wisconsin having a higher probability of heavy heart fat, whereas spring green‐up had no effect on adult female heart fat in southern Wisconsin. Effects of habitat differed by age and sex class of deer, and by the body condition metric being evaluated, indicating that there are important physiological differences among age and sex classes of deer that are affected by the environment. Our study demonstrates that the hunting public can contribute large‐scale, cost‐effective, and quality data to deer monitoring and research projects. It is important that natural resource agencies be able to identify and recruit highly engaged members of the hunting public to ensure project success. The timing of spring green‐up can have lasting effects on deer health that can be consistently observed the following fall, which is in contrast to the effects of winter severity that did not appear to persist when previous winters were mild or moderate. We encourage managers in northern or temperate regions to consider measures of spring green‐up timing in conjunction with traditional winter severity when making deer population management decisions, such as antlerless tag allocation.

Temporal variation of speciated atmospheric Hg and characteristics of size-fractioned HgP at a suburban site in Shijiazhuang City, North China

Atmospheric mercury (Hg) species were determined at a suburban site near Shijiazhuang, China from May 2016 to January 2017 to ascertain their seasonal and diurnal patterns, to identify the relationship with other parameters, and furthermore to elucidate their potential sources areas. The gaseous elemental Hg (GEM) concentration (3.66 ± 2.62 ng m−3) was about 2 times higher than the background level in the Northern Hemisphere, and the fine particulate bound Hg (HgP2.5) concentration (92.4 ± 59.6 pg m−3) was comparable to those at urban sites, while the gaseous oxidized Hg (GOM) level was quite low (5.7 ± 5.6 pg m−3). GEM and HgP2.5 concentrations exhibit pronounced seasonal (January > May > October > August) and diurnal (nighttime > daytime) patterns. In contrast, the seasonal and diurnal patterns of GOM were just opposite to those of GEM and HgP2.5. The significant positive relationship among GEM, HgP, CO, SO2, and NO2 reveals that they have similar anthropogenic sources. Interestingly, the size distributions of HgP in PM10 were observed to be unimodal during the four study periods, and peaks were all located in the fine mode (0.7–2.1 μm), and fine HgP contributed ∼70% (38.2–81.5%) of HgP10, indicating that the fine mode was the dominant size. The potential source contribution function (PSCF) result suggests that GEM level at the sampling site was highly impacted by regional sources rather than the long-range transport, and the potential source areas were predominantly located in southern Hebei and western Shandong. The results of wind rose and cluster analyses were consistent with the PSCF results.

Combining culturomic sources to uncover trends in popularity and seasonal interest in plants.

Culturomic tools enable the exploration of trends in human-nature interactions, although they entail inherent biases and necessitate careful validation. Furthermore, people may engage with nature across different culturomic data sets differently. We evaluated people's digital interest and engagement with plant species based on Wikipedia and Google data and explored the conservation implications of these temporal interest patterns. As a case study, we explored the digital footprints of the most popular plant species in Israel. We analyzed 4 years of daily page views from Hebrew Wikipedia and 10 years of daily Google search volume in Israel. We modeled popularity of plant species in these 2 data sets based on a suite of plant attributes. We further explored the seasonal trends of people's interest in each species. We found differences in how people interacted digitally with plants in Wikipedia and Google. Overall, in Google, searches for species that have utility to humans were more common, whereas in Wikipedia, plants that serve as cultural emblems received more attention. Furthermore, in Google, popular species attracted more attention over time, opposite to the trend in Wikipedia. In Google, interest in species with short bloom duration exhibited more pronounced seasonal patterns, whereas in Wikipedia, seasonality of interest increased as bloom duration increased. Together, our results suggest that people's digital interactions with nature may be inherently different depending on the sources explored, which may affect use of this information for conservation. Although culturomics holds much promise, better understanding of its underpinnings is important when translating insights into conservation actions.

Intra-Annual and Interannual Dynamics of Evaporation Over Western Lake Erie.

Evaporation (E) is a critical component of the water and energy budget in lake systems yet is challenging to quantify directly and continuously. We examined the magnitude and changes of E and its drivers over Lake Erie—the shallowest and most southern lake of the Laurentian Great Lakes. We deployed two eddy‐covariance tower sites in the western Lake Erie Basin—one located nearshore (CB) and one offshore (LI)—from September 2011 through May 2016. Monthly E varied from 5 to 120 mm, with maximum E occurring in August–October. The annual E was 635 ± 42 (±SD) mm at CB and 604 ± 32 mm at LI. Mean winter (October–March) E was 189 ± 61 mm at CB and 178 ± 25 mm at LI, accounting for 29.8% and 29.4% of annual E. Mean daily E was 1.8 mm during the coldest month (January) and 7.4 mm in the warmest month (July). Monthly E exhibited a strong positive linear relationship to the product of wind speed and vapor pressure deficit. Pronounced seasonal patterns in surface energy fluxes were observed with a 2‐month lag in E from R n, due to the lake's heat storage. This lag was shorter than reports regarding other Great Lakes. Difference in E between the offshore and nearshore sites reflected within‐lake spatial heterogeneity, likely attributable to climatic and bathymetric differences between them. These findings suggest that predictive models need to consider lake‐specific heat storage and spatial heterogeneity in order to accurately simulate lake E and its seasonal dynamics.

Seasonal distribution of abundance, biomass and secondary production of free-living nematodes and their community composition in different stream micro-habitats

Summary The nematode communities of four different micro-habitats in an unpolluted first-order stream were investigated over a 13-month period in a study of the sediment and the biofilms on dead wood, macrophytes and leaf litter. Nematode abundances, biomass and secondary production were analysed, together with the species composition, proportion of feeding types and diversity of the nematode communities of the micro-habitats. Differences between the investigated micro-habitats in terms of seasonal variations, species composition, proportion of feeding types and diversity were expected. The annual mean values of nematode abundance, biomass and secondary production differed significantly between the micro-habitats. Abundances were highest on dead wood, whereas biomass and secondary production were highest in sediment. In the sediment and on leaf litter, nematode abundance and biomass showed pronounced seasonal patterns. The largest contribution to the total secondary production of the stream was from sediment nematodes. In total, 108 nematode species were detected in the micro-habitats during the 13-month study. Comparisons between them revealed differences in nematode species composition. The annual mean species number was significantly higher in sediment and on leaf litter than on dead wood and macrophytes, whereas the annual mean Shannon-Wiener index was significantly higher in sediment than at all other micro-habitats. All micro-habitats in the studied stream, as well as the stream as a whole, were dominated by nematode species belonging to the deposit feeders. Our study clearly showed that the composition of nematode communities from different micro-habitats within a single stream reach can differ markedly.

Import vulnerability in the Middle East: effects of the Arab spring on Egyptian wheat trade

The ‘Arab Spring’ spilled over to Egypt from neighbouring Arab countries in the first half of 2011. General chaos during the political instabilities suddenly caused high uncertainty for consumers and traders, and temporarily rendered institutions dysfunctional. This eventually might have led to a negative market shock, impeding economic activity in general and, in particular, trade. Wheat is the main ingredient in the Egyptian diet and is heavily subsidised in the country. The general availability of cheap wheat flour creates a very high domestic demand for wheat. Therefore, Egypt is highly dependent on wheat imports from other countries for ensuring food security. This dependency makes the country vulnerable to increasing food prices and other shocks to the world market which might challenge flows of imports. This paper investigates the effects of domestic political instability on the wheat trade in Egypt. We analysed monthly trade data for wheat from the Comtrade Database of the United Nations, particularly imports and exports of wheat and wheat flour in Egypt from 2010 to 2014. The analysis showed pronounced and stable seasonal patterns whereby the pattern of 2011, the year of most intensive political turmoil in Egypt, was found to differ significantly from other years. We found robust evidence for a strong, negative demand shock in the second half of 2011 caused by the substantial and enduring political instabilities in the country which resulted from the Arab Spring.

Spatio-temporal distributions of piscivorous birds in a subarctic sound during the nonbreeding season

Understanding bird distributions outside of the breeding season may help to identify important criteria for winter refuge. We surveyed marine birds in Prince William Sound, Alaska, USA over nine winters from 2007 to 2016. Our objectives were twofold: to examine the seasonal patterns of piscivorous species overwintering in Prince William Sound, and to explore the relationships between spatial covariates and bird distributions, accounting for inherent spatial structure. We used hurdle models to examine nine species groups of piscivorous seabirds: loons, grebes, cormorants, mergansers, large gulls, small gulls, kittiwakes, Brachyramphus murrelets, and murres. Seven groups showed pronounced seasonal patterns. The models with the most support identified water depth and distance to shore as key environmental covariates, while habitat type, wave exposure, sea surface temperature and seafloor slope had less support. Environmental associations are consistent with the available knowledge of forage fish distribution during this time, but studies that address habitat associations of prey fish in winter could strengthen our understanding of processes in Prince William Sound.

Impact of seasonal warming on overwintering and spring phenology of blackcurrant

The rate of global warming varies on a seasonal timescale, with temperatures increasing faster in winter and spring than in summer or autumn. Temperature is a major driver of phenological events, but little information is available about the effects of non-uniform seasonal warming on plant development. Here we report phenological, metabolic and transcriptional responses of two Ribes nigrum cultivars to slightly elevated temperatures in winter and spring. Winter warming delayed floral bud break of ‘Narve Viking’, but advanced bud break of ‘Zusha’, implying genotypic differences in the magnitude of responses to warming during dormancy and in the heat accumulation phase in spring. Accordingly, more genes putatively associated with dormancy release, growth or development were up-regulated earlier in ‘Zusha’ than in ‘Narve Viking’ or showed significantly different transcript abundance in buds of plants at elevated or ambient temperatures. Primary metabolism of flower buds was largely unaffected by warming, but pronounced seasonal accumulation patterns of specific metabolites were evident. Especially bud break was associated with a dramatic remodeling of the metabolome, with differential seasonal regulation of metabolism between the two cultivars. Asymmetric warming did not increase the risk of freeze-induced damage to stems and flower primordia. The expression of several genes putatively related to freezing tolerance appeared coordinated during seasonal transitions in freezing tolerance. These data provide new insights into the timing of metabolic and transcriptional regulation during deacclimation, dormancy release and bud burst in a woody perennial, and contribute to our understanding of plant phenological responses to climate change.

Seasonal dynamics of ground cover in Cirsium arvense – a basis for estimating grazing losses and economic impacts

SummaryAnalysis of the economics of managing Cirsium arvense in grazed pastures worldwide has been hampered by a lack of data on the within‐year seasonal dynamics of the weed and its impact on the yield of palatable herbage. To redress this, the seasonal pattern in within‐patch percentage ground cover of the weed was determined from measurements on 39 dairy and 66 sheep and/or beef cattle farms in New Zealand during 2009–2010 and 2010–2011. This pattern was then scaled using farmer estimates of peak whole‐farm cover to derive mean monthly covers for dairy, beef, sheep/beef, sheep and deer farms. These monthly covers corresponded, respectively, to mean annual percentage covers of 2.7, 1.7, 3.0, 5.9 and 2.9% and to mean annual percentage losses in pasture growth (palatable herbage yield) of 3.6, 2.3, 4.0, 7.8 and 3.9%. The latter, in combination with 2011–2012 farm statistics, revealed that C. arvense caused a national loss in pastoral farm gross revenue in New Zealand in 2011–2012 of $685 million ($446 m dairy, $233 m sheep/beef, $6 m deer). Beyond the scope of this paper, the monthly covers and their corresponding monthly losses in pasture growth provide a basis for modelling the economic impacts of C. arvense and its management at a farm scale. More generally, the analytical method that we have developed is appropriate for evaluating the economic impact of any weed in a grazed pasture, particularly those exhibiting pronounced seasonal patterns in occupancy, such as annuals and deciduous perennials.

Excess winter mortality associated with Alzheimer’s Disease and related dementias in the UK: A case for energy justice

For more than 25 years, excess winter deaths (EWDs) have been associated with adverse respiratory and cardiovascular events. More recently, an association between EWDs and a new spectrum of morbidity has been noted by the Office for National Statistics (ONS) for England and Wales: since at least 2009, a high prevalence of excess winter mortality has also been evident among people living with Alzheimer’s Disease and related dementias (ADRD). In the present study, excess winter mortality data for all of the UK (England, Wales, Scotland and Northern Ireland) are analysed, using a longer time series (22 years). Results corroborate ONS findings related to elevated risk of death during winter for people living with ADRD. Seasonal effects have been sustained throughout the 22 year period, and people with ADRD emerge as being at greater risk of a winter death than people with cardiovascular conditions. Establishing the reasons for such pronounced seasonal mortality patterns among people with ADRD could help ensure better energy justice for people living with the severe mental impairments imposed by these conditions, guiding more effective delivery of energy efficiency and health services to people living with this increasingly prevalent disease spectrum.

Seasonal Changes in Tropical SST and the Surface Energy Budget under Global Warming Projected by CMIP5 Models

Abstract The seasonal changes in tropical SST under global warming are investigated based on the representative concentration pathway 8.5 (RCP8.5) and historical runs in 31 models from phase 5 of CMIP (CMIP5). The tropical SST changes show three pronounced seasonal patterns: the peak locking to the equator throughout the year and the weaker equatorial changes and stronger hemispheric asymmetric changes (HACs) in boreal autumn. The magnitude of the seasonal patterns is comparable to the tropical-mean warming and the annual-mean patterns, implying great impacts on global climate changes. The peak locking to the equator is a result of the equatorial locking of the minimum damping of climatological latent heat flux and the ocean heat transport changes. Excluding the role of ocean heat transport suggested in previous studies, the weaker equatorial warming in boreal autumn is contributed by stronger evaporation damping as a result of stronger climatological evaporation and increased surface wind speed. The seasonal variations of the HAC are driven by the variations of the damping effect of climatological evaporation. In boreal summer, the damping effect of climatological evaporation, which is greater in the Southern Hemisphere, promotes the development of the HAC. Consequently, the HAC peaks in boreal autumn when the damping effect of climatological evaporation transforms to a reverse meridional pattern, which is greater in the Northern Hemisphere. The wind–evaporation–SST feedback, as the key process of the annual-mean HAC, amplifies the seasonal variations of the HAC in tropical SST.

Mapping Threatened Dry Deciduous Dipterocarp Forest in South-East Asia for Conservation Management

Habitat loss is the primary reason for species extinction, making habitat conservation a critical strategy for maintaining global biodiversity. Major habitat types, such as lowland tropical evergreen forests or mangrove forests, are already well represented in many conservation priorities, while others are underrepresented. This is particularly true for dry deciduous dipterocarp forests (DDF), a key forest type in Asia that extends from the tropical to the subtropical regions in South-east Asia (SE Asia), where high temperatures and pronounced seasonal precipitation patterns are predominant. DDF are a unique forest ecosystem type harboring a wide range of important and endemic species and need to be adequately represented in global biodiversity conservation strategies. One of the greatest challenges in DDF conservation is the lack of detailed and accurate maps of their distribution due to inaccurate open-canopy seasonal forest mapping methods. Conventional land cover maps therefore tend to perform inadequately with DDF. Our study accurately delineates DDF on a continental scale based on remote sensing approaches by integrating the strong, characteristic seasonality of DDF. We also determine the current conservation status of DDF throughout SE Asia. We chose SE Asia for our research because its remaining DDF are extensive in some areas but are currently degrading and under increasing pressure from significant socio-economic changes throughout the region. Phenological indices, derived from MODIS vegetation index time series, served as input variables for a Random Forest classifier and were used to predict the spatial distribution of DDF. The resulting continuous fields maps of DDF had accuracies ranging from R2 = 0.56 to 0.78. We identified three hotspots in SE Asia with a total area of 156,000 km2, and found Myanmar to have more remaining DDF than the countries in SE Asia. Our approach proved to be a reliable method for mapping DDF and other seasonally influenced ecosystems on continental and regional scales, and is very valuable for conservation management in this region.

New insights into trace element wet deposition in the Himalayas: amounts, seasonal patterns, and implications.

Our research provides the first complete year-long dataset of wet deposition of trace elements in the high Himalayas based on a total of 42 wet deposition events on the northern slope of Mt. Qomolangma (Everest). Except for typical crustal elements (Al, Fe, and Mn), the concentration level of most trace elements (Sc, V, Cr, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Cs, Pb, Bi, and U) are generally comparable to those preserved in snow pits and ice cores from the nearby East Rongbuk Glacier. Cadmium was the element most affected by anthropogenic emissions. No pronounced seasonal variations are observed for most trace elements despite different transport pathways. In our study, the composition of wet precipitation reflects a regional background condition and is not clearly related to specific source regions. For the trace element record from ice cores and snow pits in the Himalayas, it could be deduced that the pronounced seasonal patterns were caused by the dry deposition of trace elements (aerosols) during their long exposure to the atmosphere after precipitation events. Our findings are of value for the understanding of the trace element deposition mechanisms in the Himalayas.

Ambient Temperature and Respiratory Virus Infection

Respiratory viruses are important pediatric pathogens with pronounced seasonal patterns of circulation. Various hypotheses have been put forth to explain the seasonality of these infections, many involving environmental factors. This review summarizes the effect of temperature on the epidemicity of respiratory viruses, with an emphasis on epidemiological findings from large-scale metanalyses, laboratory-derived data using animal models and possible mechanisms to account for viral seasonality.