Seasonal Temperature Variations Research Articles

Combined effects of climatic change and hydrological conditions on thermal regimes in a deep channel-type reservoir

The thermal regime in large reservoirs plays a significant role in the water quality and ecosystem succession; however, little is known about the impacts of regional climate changes and hydrological conditions on a sizeable stratified reservoir with strong inflow conditions, i.e., the Xiangjiaba Reservoir. Using measured data from 2014 to 2018, the monthly and seasonal variations of the water temperature, thermal stability, and their influencing factors were addressed by using empirical models. The results showed substantial variability and seasonality in the reservoir water temperature, which correlated highly with the air temperature, inflow water temperature, and discharge. Correspondingly, there was a seasonal varying thermal stratification in the reservoir's yearly cycle, with its duration being up to 4 ~ 5months, the maximum surface-bottom water temperature difference being up to 7 ~ 10°C. There were significant positive correlations between Schmidt's stability index of the thermal structure and inflow-reservoir temperature difference and the surface-bottom temperature differences, while negative correlations with large discharge. Moreover, the inflow tends to influence thermal stability by retaining hypolimnion cold water, with its maximum bottom hysteresis residence time being up to ~ 4months. Research findings indicated that climate warming in the recent 30years (1988 ~ 2017) would cause a 0.213°C/decade and 0.153kJ/m2/decade increase in reservoir surface water temperature and Schmidt's stability index, respectively. Among these variations, the inflow temperature increase caused by climate change accounted for the largest proportion, i.e., 0.16°C/decade and 0.115kJ/m2/decade. Therefore, climate warming significantly affected the thermal regimes in this large reservoir, and the inflow water temperature increase due to warm air was the main factor altering the reservoir's thermal structure. Findings from the present study provide a fresh perspective on how to best optimize the deep channel-type reservoirs' water quality in the face of anticipated climate change.

Correction of the Temperature Effect of Muon Counts Observed at the Guangzhou Station

Muons are the main component of secondary cosmic rays, and the variation in muon intensity indicates the variation in primary cosmic ray intensity. However, before using muons to study the variation in the intensity of cosmic rays, it is necessary to eliminate the atmospheric effects, such as pressure and temperature effects. In this work, the temperature effect of the muons is corrected in terms of empirical method by using ground temperature. The temperature correction is applied to the muon data observed at the Guangzhou station during the period 2010–2021 after a barometric correction. It is found that the effect of seasonal variations in temperature on muon counts is greatly eliminated in the corrected data. Furthermore, the muon data are well correlated with the neutron data in comparison, which verifies the reliability of the corrected muon data. Our results show that the correction of muon data by using ground temperature is an effective method.

Assessment of Antarctic Amplification Based on a Reconstruction of Near-Surface Air Temperature

Polar amplification has been a research focus in climate research in recent decades. However, little attention has been paid to Antarctic amplification (AnA). We have examined the variations in annual and seasonal temperature over the Antarctic Ice Sheet and its amplification based on reconstruction covering the period 2002–2018. The results show the occurrence of annual and seasonal AnA, with an AnA index greater than 1.39 with seasonal differences, and that AnA is strong in the austral winter and spring. Moreover, AnA displays regional differences, with the greatest amplification occurring in East Antarctica, with an AnA index greater than 1.51, followed by West Antarctica. AnA is always absent in the Antarctic Peninsula. In addition, amplification in East Antarctica is most conspicuous in spring, which corresponds to the obvious warming in this season; and the spring amplification signal is weakest for West Antarctica. When considering the influence of the ocean, the AnA becomes obvious, compared to when only the land is considered. Southern Annular Mode (SAM), surface pressure and westerlies work together to affect the temperature change over Antarctica and AnA; and SAM and surface pressure are highly correlated with the temperature change over East Antarctica. The picture reflects the accelerated changes in Antarctic temperature.

Associations between temperature variations and tourist arrivals: analysis based on Baidu Index of hot-spring tourism in 44 cities in China.

Hot-spring tourism refers to entertainment, health preservation, commercial conferences, and other leisure activities at hot-spring locations. This tourism often shows periodic variability, which may be due to seasonal temperature variations. However, studies on the effects of temperature variations on tourist arrivals at hot springs are limited. Therefore, this study aimed to evaluate this relationship in 31 provincial capital cities and 13s-tier cities in China. Using the Baidu Index, we obtained data for tourist arrivals to hot springs in each city and constructed a generalised additive model to explore the associations between temperature variations and tourist arrivals. We also analysed the statistical significance of the estimated effects during different seasons to explore potential effect modification. A 1°C increase in temperature was associated with a 1.81% (95% confidence interval (CI): 1.69-1.93) decrease in daily tourist arrivals for hot-spring tourism. Significant positive associations between the abovementioned factors were observed in summer (2.18% change, 95% CI: 1.32-3.04). The effect of temperature on the volume of tourist arrivals may last for approximately 2months. Robustness analysis confirmed the data reliability. The results indicate that significant relationships exist between temperature variations and hot-spring tourism arrivals, which vary seasonally. This study has significant implications for travel agencies to effectively manage tourist visits to hot spring locations.

Global photosynthetic capacity of C3 biomes retrieved from solar-induced chlorophyll fluorescence and leaf chlorophyll content

The maximum Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax) has been widely used to help determine the photosynthetic capacity for carbon cycle modelling. Field measurements of Vcmax are very limited, so fixed Vcmax values over growing seasons are often used, causing considerable uncertainties in modelled results. Also, the lack of a global Vcmax dataset with seasonal variations limits our understanding of the spatial and temporal patterns of Vcmax, and hence photosynthesis. This study proposes a refined data assimilation scheme to retrieve daily Vcmax using remotely sensed solar-induced chlorophyll fluorescence (SIF) and leaf chlorophyll content (LCC) data. Using the refined method, we produced a global Vcmax dataset with daily 0.1° × 0.1° resolutions. The seasonal variations in Vcmax have been successfully retrieved. Vcmax retrieved in this study was compared with field-measured Vcmax from past literature. Good agreements were achieved in relation to Vcmax measured at 201 sites (R2 is 0.78, and relative RMSE is 34%) and the seasonal variation in Vcmax measured at 9 sites (R2 ranges from 0.57 to 0.99, and the relative RMSE ranged from 6% to 28%). Our method effectively utilizes the information from both SIF and LCC, showing advantages over previous approaches that estimate Vcmax based solely on using SIF or LCC. Our results suggest that the spatial distribution of Vcmax depends on the spatial distribution of biomes, along with air temperature and absorbed photosynthetically active radiation (APAR). Higher seasonal mean air temperature and APAR tend to lead to higher seasonal mean Vcmax. The seasonal variation in Vcmax is driven by the seasonal variations in air temperature and APAR, rather than their seasonal means. We also derived and analyzed Vcmax25, which is Vcmax normalized to 25 °C (Vcmax25) and has been found to be more closely related to the Rubisco content. Vcmax25 also has considerable spatiotemporal variations, and the variations differ to that in Vcmax. Different biomes have different ratios of Vcmax25 to LCC. Air temperature and APAR exert weak but positive effects on the seasonal variation in Vcmax25. Vcmax retrieved in this study enhances our understanding of the spatiotemporal pattern of leaf photosynthetic capacity on the global scale and is potentially useful to terrestrial carbon cycle modelling.

The effect of asphaltic support layers on slab track dynamics

The deployment of asphaltic support layers (ASLs) within railway track structures has the potential to increase track bending stiffness, assist moisture runoff and provide a platform for track construction. These merits have increased its usage within the rail industry, however the understanding of asphaltic track dynamics during train loading remains limited. Therefore, the primary aim of this study is the development of new knowledge into the dynamic behavior of concrete slab track systems enhanced with asphaltic underlays. To do so, a numerical simulation approach is used, comprised of two sub-models: 1) a coupled multi-body vehicle−track model, for the purpose of computing wheel/rail forces; and 2) a 3D dynamic finite element track-ground model to simulate stress wave propagation in the sub-structure. The models are validated using both analytical results and field tests, and then used to simulate slab track systems with ASL thicknesses of: 0, 0.05, 0.07, 0.10, and 0.15 m. First the dynamic response at locations both near and far from the track joints are compared to quantify the asphaltic foundation stresses, deflections, accelerations and strains. It is found that stress concentrations occur near the concrete base joints and are an important consideration for ASL design. Next, asphalt concrete durability at 400 km/h line speed is explored considering seasonal temperature variations and it is found that the expected cumulative damage meets serviceability requirements. Finally, the influence of different asphaltic layer thicknesses on reaction modulus is discussed, concluding that the optimal thickness range, considering plastic deformation and construction constraints, is between 0.07 m and 0.10 m.

Molecular breeding of barley for quality traits and resilience to climate change.

Barley grains are a rich source of compounds, such as resistant starch, beta-glucans and anthocyanins, that can be explored in order to develop various products to support human health, while lignocellulose in straw can be optimised for feed in husbandry, bioconversion into bioethanol or as a starting material for new compounds. Existing natural variations of these compounds can be used to breed improved cultivars or integrated with a large number of mutant lines. The technical demands can be in opposition depending on barley's end use as feed or food or as a source of biofuel. For example beta-glucans are beneficial in human diets but can lead to issues in brewing and poultry feed. Barley breeders have taken action to integrate new technologies, such as induced mutations, transgenics, marker-assisted selection, genomic selection, site-directed mutagenesis and lastly machine learning, in order to improve quality traits. Although only a limited number of cultivars with new quality traits have so far reached the market, research has provided valuable knowledge and inspiration for future design and a combination of methodologies to achieve the desired traits. The changes in climate is expected to affect the quality of the harvested grain and it is already a challenge to mitigate the unpredictable seasonal and annual variations in temperature and precipitation under elevated [CO2] by breeding. This paper presents the mutants and encoded proteins, with a particular focus on anthocyanins and lignocellulose, that have been identified and characterised in detail and can provide inspiration for continued breeding to achieve desired grain and straw qualities.

Seasonal variation in diet and isotopic niche of nominally herbivorous fishes in subtropical rocky reefs

Herbivorous fishes can be sensitive to environmental fluctuations, which influence both availability of food resources and metabolic rate, and thus nutritional requirements. Impacts on herbivore nutritional ecology may result from seasonal variations in temperature and meteoceanographic shifts such as wind-induced upwelling events. We evaluated the effects of seasonal changes on the nutritional ecology of 3 nominally herbivorous fishes (Acanthurus chirurgus, Sparisoma axillare and Kyphosus vaigiensis) in a subtropical rocky reef on the southeastern Brazilian coast using a combination of gut content analysis (at 2 scales of magnification) and stable isotope analysis. Sampling of in situ water temperature covered both patterns of seasonal variation in sea surface temperature, and seasonal occurrence of upwelling. Local upwelling occurred throughout the year but less frequently in winter. Diet and isotopic niche displayed little seasonal variation. Species-specific patterns of seasonal variation indicated distinct responses to environmental fluctuations. Temperature alone cannot explain the locality-specific variation in the nutritional ecology of herbivorous reef fish, and contrary to predictions that digestion in herbivorous fishes is impaired by cooler temperatures, no significant shifts in species’ nutritional ecology were detected.

Monitoring of seasonal variations in ground temperature at the observation site of Lomonosov MSU

The paper considers the problem of monitoring seasonal variations of ground temperature in northern and mountainous areas in the light of ongoing climate changes. To study seasonal variations of ground temperature, a model site of the Moscow State University Meteorological Observatory was used with the ability to monitor air temperature, snow cover thickness, and ground freezing temperature and depth, which was a prototype of a system for monitoring the state of permafrost soils used in the Arctic and mountain territories. The paper presents the results of monitoring seasonal variations of ground temperature based on the results of numerical modelling of the propagation of seasonal fluctuations of ground temperature in 2014-2017 in MATLAB environment which are in good agreement with the thermometry data and, therefore, the developed calculation scheme shows fairly good simulation results. This makes it possible to use the calculation scheme to assess the thermal state of frozen grounds and the stability of foundations and buildings and linear constructions located on them in the conditions of the North and mountainous territories. Therefore, the presented methodology can serve as a good help for monitoring and preventing the destruction of the observed structures in the conditions of climate warming.

Spatio-temporal patterns of different tree species response to climatic factors in south Kyrgyzstan

Understanding forest phenology is essential for monitoring global carbon budgets and managing vegetation resources in a changing climate. In southern Kyrgyzstan, walnut and wild apple trees dominate the forest landscape. These forests contain unique genetic diversity and offer potential for the development of climate-resilient crop varieties. They also support local communities through activities such as grazing, firewood collection, and fruit harvesting. However, these practices pose a threat to natural regeneration. Climate change exacerbates these challenges by altering their ecological niche. Despite this, few studies have examined forest phenology and its relationship to climate in Kyrgyzstan. To address this gap, we collected ecological data from forest plots in several protected areas and one forestry unit. This included tree species coordinates and landscape. Time series of vegetation indices, land surface temperature and precipitation were generated from remote sensing data. Regression analyses showed that temperature trends had limited predictive power for vegetation, while seasonal temperature variations had a positive effect on vegetation until excessive heat was reached, which had a negative effect. Precipitation trends and seasons had the most significant effects on vegetation, with lagged effects. Regression models were developed for Juglans regia L. (R2=0.8) and Malus spp. (R2=0.75) to predict vegetation index from temperature and precipitation data with high accuracy. Spatial heterogeneity in species response to climatic factors was evident within a small area. The study highlights the influence of landscape and climatic diversity on forest dynamics and emphasizes the importance of seasonal climate patterns over interannual trends.

Large-scale and regional climatic influences on surface temperature and precipitation in the South Shetland Islands, northern Antarctic Peninsula.

Using data from SCAR observations, ERA5 reanalysis, and regional climate model simulations (RACMO), we examined the influence of large- and regional-scale climate forcing on temperature and precipitation variations in the South Shetland Islands (SSI). Specifically, we focused on understanding how regional climate indices influence the temporal variability of temperature and precipitation on the SSI. Our findings indicate that both large- and regional-scale climate indices significantly impact the interannual and seasonal temperature variability in the SSI. For instance, the Amundsen Sea Low, characterised by low-pressure systems over the Amundsen Sea, and sea ice extent in the northwestern part of the Weddell Sea, exert a strong influence on temperature variability (r from -0.64 to -0.87; p < 0.05). In contrast, precipitation variability in this region is primarily controlled by regional climatic indices. Particularly, anomalies in atmospheric and surface pressure over the Drake Passage region strongly regulate the interannual variability of precipitation in the SSI (r from -0.46 to -0.70; p < 0.05). Large-scale climatic indices demonstrate low but statistically significant correlations, including the Southern Annular Mode and deep convection in the central tropical Pacific. Given the importance of temperature and precipitation in the glacier changes, we recommend assessing the impact of the Drake region on SSI glaciers.

Seasonal and interannual variations in sea surface temperature in the Tatar Strait according to satellite data

The aim of the work was to conduct a systematic statistical analysis of the spatial and temporal variability of sea surface temperature (SST) in the waters of the Tatar Strait based on satellite data accumulated in the Sakhalin branch of VNIRO using the TeraScan receiving station for 1998‒2021. It was revealed that in different seasons of the year the SST structure is similar and characterized by the highest values in the southeast and the lowest in the northwest of the strait. An important new result was obtained by expanding of the SST field in terms of the EOF, which is associated with a sharp change in the nature of the time function of the third mode, which occurred in 2013–2014. Such changes can be considered as a climatic shift in the studied area most pronounced in the northwestern part of the strait and near the southwestern coast of Sakhalin Island, where the change was about 1 °C. This circumstance can have a noticeable effect on the state of populations of several species of shrimp and commercial fish.

Existential threats to pastoralism in an arid environment: the fate of Gujii pastoralists in Southern Ethiopia

&lt;span lang="EN-GB"&gt;The pastoralists of Gujii have faced numerous risks, with their pastoralism system facing serious challenges. With the technically inconsistent and timely unmanaged interventions, several pastoral households are facing unreserved challenges. As a result, the future of pastoralists appears to be in great danger. The objective of this study is to investigate the ongoing challenges of Gujii pastoralism, as well as the fate of pastoralists in southern Ethiopia who are suffering from unrelenting drought. Ethiopian Meteorological Agency provided monthly rainfall and temperature data from 1986 to 2016. A household survey was conducted with 340 household heads randomly chosen from the study area to examine the challenges of the pastoralists have been facing. Moreover, a key informant interview and a focus group discussion were employed to collect qualitative data. Each watershed unit held one round of focus group discussions, with an average of 7-10 participants. The coefficient of variation (CV) was used to detect the temporal variability of seasonal rainfall and temperature. To detect trends, the Mann Kendall (MK) and Sen's slope estimator were used to determine the trends and magnitude of the change. Political and tenure insecurity seriously affected the pastoral system in different ways. Autumn and spring had high variability in rainfall, with CV = 48.76% and 32.43%, respectively. Both winter and spring temperatures show a significant increase at (a = 0.1). Climate variability has made the already fragile pastoral households even more vulnerable. Pastoralist’s future would be difficult with all of these problems, and its resilience would be doubtful. As a result, in order to ensure the pastoral's long-term survivability, the government.&lt;/span&gt;

ТЕМПЕРАТУРА И ХИМИЧЕСКИЙ СОСТАВ ТЕРМОМИНЕРАЛЬНЫХ ВОД ДАГИНСКИХ ИСТОЧНИКОВ (о. САХАЛИН) ПОСЛЕ ПРОВЕДЕНИЯ РЕКОНСТРУКЦИИ КАПТАЖНЫХ СООРУЖЕНИЙ В 2019–2020 гг.

The paper presents the results of the study of physical and chemical characteristics of thermo-mineral waters of the Daginsky field (Sakhalin Island) after the reconstruction of the captation structures in 2019–2020. The analysis of the data indicates the stability of the chemical composition of thermo-mineral waters before and after reconstruction works on the territory of springs. The thermo-mineral waters had a typical Cl-Na composition, and the values of the hydrogeochemical indicators did not exceed the range of values established by the analysis of data for these waters over a multi-year period (1958–2019). However, for most of the springs whose captation structures underwent reconstruction, a significant drop in the surface temperatures of thermo-mineral waters (by 5–15°C) was recorded. The indicated temperature anomaly is not related to changes in the origin of discharged thermo-mineral waters or to seasonal air temperature variation. The observed drop in temperatures may be a consequence of a decrease in the flow rates of the springs after construction work, as well as technically incorrect design of the thermal baths.

Analysis of monthly, seasonal and annual air temperature variability and trends in Gujarat

Analysis of monthly, seasonal and annual air temperature variability and trends in Gujarat

Long-term patterns of hydrocarbon biodegradation and bacterial community composition in epipelagic and mesopelagic zones of an Arctic fjord

Oil spill attenuation in Arctic marine environments depends on oil-degrading bacteria. However, the seasonally harsh conditions in the Arctic such as nutrient limitations and sub-zero temperatures limit the activity even for bacteria capable of hydrocarbon metabolism at low temperatures. Here, we investigated whether the variance between epipelagic (seasonal temperature and inorganic nutrient variations) and mesopelagic zone (stable environmental conditions) could limit the growth of oil-degrading bacteria and lead to lower oil biodegradation rates in the epipelagic than in the mesopelagic zone. Therefore, we deployed absorbents coated with three oil types in a SW-Greenland fjord system at 10–20 m (epipelagic) and 615–650 m (mesopelagic) water depth for one year. During this period we monitored the development and succession of the bacterial biofilms colonizing the oil films by 16S rRNA gene amplicon quantification and sequencing, and the progression of oil biodegradation by gas chromatography – mass spectrometry oil fingerprinting analysis. The removal of hydrocarbons was significantly different, with several polycyclic aromatic hydrocarbons showing longer half-life times in the epipelagic than in the mesopelagic zone. Bacterial community composition and density (16S rRNA genes/ cm2) significantly differed between the two zones, with total bacteria reaching to log-fold higher densities (16S rRNA genes/cm2) in the mesopelagic than epipelagic oil-coated absorbents. Consequently, the environmental conditions in the epipelagic zone limited oil biodegradation performance by limiting bacterial growth.

Hydroclimate seasonality from paired coral Sr/Ca and δ18O records of Kikai Island, Southern Japan: Evidence of East Asian monsoon during mid-to late Holocene

The East Asian Monsoon (EAM) modulates the seasonal variability of sea surface temperature (SST), sea surface salinity (SSS), and rainfall in the region. However, seasonal-scale reconstructions showing the hydroclimate response to monsoon intensity shifts in Holocene are limited. We used paired coral Sr/Ca and oxygen isotope (δ18Ocoral) records from modern (1989–2015), 5.7 ka, 4.9 ka, and 3.2 ka corals from Kikai Island, Southern Japan to reconstruct past seasonal variability of hydroclimatic variables. The monthly δ18Ocoral-SSS relationship revealed a statistically significant positive linear correlation (r = 0.63; p < 0.000; n = 310) while the δ18Osw and rainfall showed a statistically significant negative linear correlation (r = 0.55; p < 0.000; n = 93).The large SST and SSS seasonality in 5.7 ka (ΔSSTmax-min = 9.5 °C; Δδ18Omax-min = 1.86‰) and 4.9 ka (ΔSSTmax-min = 10.2 °C; Δδ18Omax-min = 1.45‰) indicate an enhanced seasonal ocean warming which amplified the Western Pacific Subtropical High (WPSH) and the southwesterlies. In contrast, the small SST amplitude in 3.2 ka (ΔSSTmax-min = 7.8 °C; Δδ18Omax-min = 0.98‰) indicates a weakened WPSH and southwesterlies which led to reduced summer rainfall and positive SSS signal. The lower salinity records due to higher rainfall in 7.0 ka, 6.1 ka, 5.7 ka, and 4.9 ka coincide with the strong East Asian summer monsoon (EASM) from 8.2 to 4.7 ka in stacked sediment records. The δ18Ocoral record shows positive SSS driven by weakened summer monsoon rainfall in 4.4 ka, 4.2 ka, 3.8 ka, 3.4 ka, and 3.2 ka.The higher winter SSS (positive δ18Ocoral) and lower winter SST derived from 5.7 ka coral in Kikai Island agree with the strong East Asian winter monsoon (EAWM) intensity from 8.2 to 5.6 ka based on the stacked sediment record. The weak EAWM phase from 5.6 ka to 4.5 ka is consistent with the winter records of warm SST and lower SSS in 4.9 ka. The lower winter SSS and warmer winter SST in 3.2 ka support the evidence of a weak phase around 3.0 ka. The extratropical systems such as the intensified or weakened Siberian High and Aleutian Low have affected the northeasterly EAWM and consequently influenced the variability of winter SST and SSS in subtropical southern Japan in mid- and late Holocene.

Coral Sr/Ca-derived seasonal sea surface temperature variations in the Qiongdong upwelling area of the northern South China Sea during the Medieval Climate Anomaly

Geological records of seasonal sea surface temperature (SST) records are useful for better understanding the past dynamics of coastal upwelling, and for inferring future scenarios. By using Sr/Ca records obtained from Porites lutea corals in the Qiongdong upwelling (QDU) area of the northern South China Sea (SCS), seasonal SST variations were reconstructed for the 1129–1263 CE interval of the Medieval Climate Anomaly (MCA). On an annual scale, summer SST is negatively correlated with the intensity of the East Asian Summer Monsoon (EASM), indicating a dominant role of the EASM on summer SST in the QDU area. The lack of correlation between winter SST and the East Asian Winter Monsoon (EAWM) may result from the dating errors of the climate archives and the low temporal resolution of EAWM records. Winter SST and summer SST played similarly affected the SST seasonality during the MCA. On the centennial scale, the differences in the averages of summer SST and winter SST in the QDU area between the MCA and the Current Warm Period were attributed to the different EASM and EAWM intensities. The consistent variations between the summer QDU and the winter Sumatra-Java upwelling during both climate intervals may imply that the SST variabilities in these two coastal upwelling systems responded to cross-equatorial winds originating from the Indian Ocean.

A high-resolution ocean bottom temperature product for the northeast U.S. continental shelf marine ecosystem

The northeast U.S. continental shelf is a highly productive and socio-economically important marine ecosystem in which annual and seasonal variations of bottom temperature play a major role in the distribution, phenology, and productivity of its predominately demersal marine taxa. However, bottom temperature measurements are limited spatially and temporally and thus do not provide the required resolution to assess sub-seasonal variability and trends. Here we combined three ocean products, a regional ocean model (ROMS) and two global ocean data assimilated models (GLORYS12v1 and PSY4V3R1) to build a high-resolution, long-term bottom temperature product for the northeast U.S. continental shelf between 1959 and 2021. We bias-corrected ROMS using monthly decadal climatologies from ocean observations and analyzed long-term changes in the combined time series. Model skill was assessed using a large number of in situ observations. The combined bottom temperature product showed a long-term warming of the northeast U.S. continental shelf of + 0.36 °C decade-1 over the past 63 years, with notable variations among seasons and regions. The strongest long-term warming occurred during the summer months and in the Gulf of Maine. Although biases were observed, the bottom temperature product exhibited good performance reproducing seasonal and annual variability in observed temperature. This high-resolution product could be used in a wide range of applications from local to regional spatial scales, from long-term to near-term time scales, and from fisheries to marine ecology.

Diaspore dispersal season influences root growth and seed traits, but not germination responses, of sympatric Piper species in a seasonal forest.

Seeds may differ in terms of dormancy, longevity, sensitivity to desiccation and dry mass, according to the timing (dry season/rainy season) of diaspore dispersal. In addition, seasonal variations in temperature and water availability can act as signals of the season during seed development, influencing germination responses and root growth. We evaluated the effects of temperature variations and water availability on germination parameters, root growth and seed traits of four coexisting Piper species in seasonal vegetation that differed in diaspore dispersal timing. Eight temperature treatments (15, 20, 23, 25, 28, 30, 35 °C, and alternate 30 °C-20 °C) and four induced water potentials (0, -0.3, -0.6 and -1.2 MPa) were used. The parameters germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage and dry mass of seeds were evaluated. Germination responses observed were independent of the diaspore dispersal timing, such as variations in germination onset, G% and MGT, both in temperature and water availability treatments. In contrast, root elongation, longevity and dry mass of seeds varied according to the time of diaspore dispersal. Our results corroborate the hypothesis that the timing of diaspore dispersal is an important factor in controlling the initial development of seedlings in seasonal vegetation, but not in germination responses. The predominance of negative effects of temperature increases and water deficit on root growth shows that the initial stages of plant development can be strongly impacted by these environmental factors.