Elevation Changes Research Articles

SmoothRide: A Versatile Solution to Combat Cybersickness in Elevation-Altering Environments.

Cybersickness continues to bar many individuals from taking full advantage of virtual reality (VR) technology. Previous work has established that navigating virtual terrain with elevation changes poses a significant risk in this regard. In this paper, we investigate the effectiveness of three cybersickness reduction strategies on users performing a navigation task across virtual elevation-altering terrain. These strategies include static field of view (FOV) reduction, a flat surface approach that disables terrain collision and maintains constant elevation for users, and SmoothRide, a novel technique designed to dampen a user's perception of vertical motion as they travel. To assess the impact of these strategies, we conducted a within-subjects study involving 61 participants. Each strategy was compared against a control condition, where users navigated across terrain without any cybersickness reduction measures in place. Cybersickness data were collected using the Fast Motion Sickness Scale (FMS) and Simulator Sickness Questionnaire (SSQ), along with galvanic skin response (GSR) data. We measured user presence using the IGroup Presence questionnaire (IPQ) and a Single-Item Presence Scale (SIP). Our findings reveal that users experienced significantly lower levels of cybersickness using SmoothRide or FOV reduction. Presence scores reported on the IPQ were statistically similar between SmoothRide and the control condition. Conversely, terrain flattening had adverse effects on user presence scores, and we could not identify a significant effect on cybersickness compared to the control. We demonstrate that SmoothRide is an effective, lightweight, configurable, and easy-to-integrate tool for reducing cybersickness in simulations featuring elevation-altering terrain.

Performance Assessment of Three Living Shorelines in Cedar Key, Florida, USA

A community-driven effort in Cedar Key, Florida, USA, resulted in the construction of three living shoreline retrofits intended to bolster failing coastal infrastructure and restore habitat functions in Daughtry Bayou. A multi-year monitoring program tracked changes in elevation and vegetation communities across the entire shoreline profile from lower-intertidal to upland/transitional zones and measured wave attenuation during typical and extreme (hurricane) conditions. Overall, these living shoreline retrofits served to soften more than 30% of the bayou’s shoreline, dramatically reducing the extent of armored shoreline in direct contact with tidal influence. The extent of vegetated habitat area has increased at all three sites, despite sediment export from higher elevation zones driven largely by repeated impacts from hurricanes and tropical storms. These living shorelines reduced wave energy by 33 to 79% in typical conditions and by up to 28% in hurricane conditions, consistently outperforming armored shorelines, even during an extreme event (Hurricane Idalia). Our monitoring efforts were sufficient to capture project trajectories and assess performance relative to project goals, but our program had limitations that could have been overcome with additional resources and increased focus on capturing spillover effects. The living shoreline retrofit projects assessed here have persisted through and shown signs of recovery after multiple tropical storms and hurricanes, while providing important energy reduction services. Thus, living shoreline retrofits continue to be a cost-effective shoreline management strategy in the short term for this area. However, our analyses suggest that persistence of these shorelines could be threatened by the combination of sea-level rise (by 2040), upland armoring, and an increasing risk of more intense tropical systems. Therefore, future interventions should more carefully consider these threats in conjunction with habitat enhancement goals.

Elevation, Soil and Environmental Factors Determine the Spatial and Quantitative Distribution of Qinghai Spruce Recruitment Biomass in Mountainous (Alpine) Watersheds

Soil heterogeneity observed in the alpine environment plays a very important role in the growth of forest recruitment. However, the mechanisms by which the biomass accumulation and allocation patterns of forest recruitment respond to such environmental differences are unclear, which hinders a thorough understanding of climate change’s impact on forest biomass. We hypothesized that soil heterogeneity influences the distribution of Qinghai spruce recruitment biomass along with elevation. In the frame of this study, carried out in the northern Tibetan Plateau, forest Qinghai spruce recruitment data were combined with soil data derived from 24 sample plots, while permutation multifactor ANOVA and multiple linear regression were utilized to reveal the characteristics of forest recruits’ above- and below-ground biomass and their allocation patterns in response to soil heterogeneity. According to the results, the soil heterogeneity mainly affected the distribution characteristics of recruits’ above- and below-ground biomass at different elevations, while the recruits’ root–shoot ratio variability was influenced by a combination of soil and other environmental factors. Soil organic carbon (SOC) had the greatest effect on the variability of the above- and below-ground biomass of spruce recruits, with R2 of 0.280 and 0.257, respectively. Soil organic carbon and soil moisture content (SMC) had a significant effect on the variability of the root–shoot ratio, with R2 of 0.168 and 0.165, respectively. Soil total nitrogen (TN) and soil organic carbon were the main influencing factors of the above-ground biomass of forest recruits, with contribution rates of 43.15% and 35.28%, respectively. Soil total nitrogen and soil organic carbon were also the main factors influencing the below-ground biomass of forest recruits, with contribution rates of 42.52% and 37.24%, respectively, and both of them had a positive effect on biomass accumulation, and the magnitude of the influence varied with the elevation gradient. Soil moisture content was the main influence factor of spruce recruits’ root–shoot ratio, with a contribution rate of 54.12%. Decreasing soil moisture content would significantly increase the root–shoot ratio of spruce recruits and promote plants to allocate more biomass to root growth. Changes in elevation not only affected the intensity of the effect of soil factors on spruce recruitment biomass and its allocation pattern but even led to a change in the positive and negative effects.

Assessing hydrodynamic impacts of tidal range energy impoundments in UK coastal waters

Tidal range energy comprises a vast theoretical resource of 9,220 TWh per year, globally, with advantageous characteristics of predictability, generation flexibility and reliability. Approximately 13% of this resource lies within the United Kingdom’s (UK) coastal waters, where it could supply up to 12% of annual electricity demand. Tidal range energy conversion traditionally involves constructing and operating large-scale coastal or offshore impoundments (O10-100 km2), which will redefine near and far-field water levels and flow patterns. The relationship between the scale of the impoundment area and hydrodynamic impact has not been investigated for UK sites. To address this, we develop a two-dimensional (depth-averaged) TELEMAC model of the Irish Sea, and simulate six scenarios involving tidal range schemes of increasing basin area, from 25 to 150 km2, located on the North Wales coast in an open coastal basin setting. Results indicate that far-field (30−150 km) changes to the amplitude of the semi-diurnal (M2) tidal constituent exhibit a linear relationship with impoundment area and volume (correlation coefficient R=0.95 and R=0.96, respectively). The largest impoundment (150 km2) caused far-field changes in maximum surface elevation (2<ηmax<3 cm); near-field surface elevation was reduced (ηmax>3 cm).

Validation and Analysis of the ICESat-2 ATL11 Product: A Case Study of Lake Vostok

Elevation changes are crucial input data for mass balance assessment based on satellite altimetry. However, due to the accuracy limitations of altimetry data and mass conversion models, a significant uncertainty remains in estimating the mass balance of the Antarctic ice sheet, especially in East Antarctica. The ICESat-2 photon altimetry satellite enhances the precision of ice sheet surface elevation measurements to an accuracy of 2–4 cm. This improvement is particularly beneficial for detecting subtle elevation changes in East Antarctica. The ATL11 product from ICESat-2 offers a time series of ice surface elevations across Antarctica, enabling direct calculation of elevation change rates. To evaluate the capability of the ATL11 product in accurately depicting detailed elevation changes within the local terrain, we selected the Vostok Subglacial Lake as the validation region. Our research involves comparing fitted surface elevation change rates with in-situ data, while also considering surface mass balance, wind, and surface elevation to analyze the factors contributing to small differences in elevation changes within the local lake area. This analysis aims to identify the factors contributing to the minor variations in elevation changes within the local lake area. According to our analysis, the Vostok Lake surface elevation change rate is 2.00 ± 0.77 cm yr−1 from April 2019 to June 2023, with an average period of 356 ± 81 days. The results demonstrate that the ATL11 elevation product sequence has the potential to accurately characterize subtle elevation changes and seasonal variations in the Antarctic ice sheet.

Characteristics of dynamic thickness change across diverse outlet glacier geometries and basal conditions

Abstract Outlet glaciers in Greenland are undergoing retreat and diffusive thinning in response to external forcings, but the rates and magnitudes of these responses differ from glacier to glacier for unclear reasons. We test how changes in ice overburden pressure and basal lubrication affect diffusive thinning rates and their spatial patterns by conducting numerical experiments over various idealized Greenland-like glacier domains. We find that ~10 km frontal retreat over a decade can produce sustained thinning rates as large as 16 m a−1 due to ice overburden pressure changes, at outlet glaciers with high basal drag (&gt;60 kPa) and lateral resistive stress (&gt;70 kPa). Localized basal lubrication perturbations induce upstream thinning and downstream thickening up to 12 m a−1; the duration of the lubrication forcing generally has a greater effect than its intensity on induced thickness changes. Lastly, episodic grounding line retreats over a rough bed produce a stepped time series of thinning broadly consistent with observations of dynamic elevation change on multiple Greenland glaciers. Our findings highlight the critical role of the total grounding zone – not ice front position – through the resistive stress change in relation to total glacier thinning.

An Acoustic Sensor System to Measure Aeolian Ripple Morphology and Migration Rates.

Acoustic distance sensors have a long history of use to detect subaqueous bedforms. There have been few comparable applications for aeolian bedforms such as ripples. To address this, we developed a simple and reliable apparatus comprising a pair of distance sensors, a bracket upon which they are mounted, and a base upon which the bracket can slide. Our system relies on two Senix Corporation (Hinesburg, VT, USA), ToughSonic® model 14-TSPC-30S1-232 acoustic distance sensors: one to measure surface elevation changes (in this case, ripple morphology) and a second to measure horizontal location. The ToughSonic® vertical resolution was 0.22 mm and the horizontal scan distance was about 0.60 m with a locational accuracy of 0.22 mm. The measurement rate was 20 Hz, but we over-sampled at 1 KHz. Signal processing involves converting volts to meters, detrending the data, and removing noise. Analysis produces ripple morphologies and migration rates that conform with independent measurements. The advantages of this system relative to terrestrial laser scanning or structure from motion are described.

Environmental risks associated with quarry activities and its anthropogenic changes in Weija Hills, Ga South Municipal, Ghana

Quarrying has become an important socio-economic activity in many societies as it provides several services for human well-being. Weija Hills at the Ga South Municipality in Ghana has been witnessing quarrying activities at various sections of the hills causing a series of environmental problems. The study examined the changes that have occurred in the geological structure of the Weija Hills and its environmental hazards. The study employed the mixed method approach following the exploratory sequential research design. The primary data were collected directly from field observation during which much data was gathered including photographs. The Digital Elevation Model (DEM) was used for elevation changes between 2007 and 2014. The Limit Equilibrium Method (LEM) was used for slope stability analysis. The study found that the Weija Hills's local geology is still stable. However, serious environmental problems such as erosion taking place and large quantities of weathered and eroded sediments being carried downslope any time it rains blocking the Mallam-Kasoa Highway making it risky for road users. We recommended that the Minerals Commission and other stakeholders should collaborate and reclaim the land.

A Binned Multilevel Regression Fitting Method for Monitoring Geladandong Glacier Elevation Changes from ICESat-2 Data

ABSTRACT Studying glacier changes is essential for understanding global glacier mass balance, patterns in climate change, and the potential consequences they may have. The glaciers of Geladandong Mountain serve as a crucial water source for the Yangtze River and its downstream regions. Any changes in the glacier at the river source will directly impact the ecological environment and water recycling process downstream. This study presents an approach for monitoring Geladandong Mountain glacier elevation changes using ICESat-2 data combined with a Binned Multilevel Regression Fitting Method (BMRFM). We analysed multi-year ICESat-2 data, considering various topographic features, to understand glaciers’ annual and seasonal elevation changes. Our research reveals significant spatial heterogeneity in glacier elevation changes, influenced by altitude, slope, and aspect factors. It demonstrates the effectiveness of ICESat-2 in glacier monitoring, offering insights into the impacts of climate change on glacier dynamics. Moreover, the results indicate a predominant trend of ongoing melting at lower altitudes, with a small amount of accretion at higher elevations. Over the last two decades, the overall elevation change rate is −0.23 ± 0.12 metres per year. Seasonal analysis shows substantial glacier thickening from April to August, primarily due to increased precipitation offsetting elevated temperatures. This study offers a robust method for monitoring glaciers using satellite data, thereby advancing the precision and reliability of glacier research.

Dynamic fluid flow model for phosphate slurry pipeline: OCP main pipeline as case study

The transportation of phosphate slurry through large-scale pipelines presents significant challenges due to the complex behavior of multiphase flows, particularly with varying solid content, density, and dynamic viscosity. Efficient and accurate prediction of flow behavior is critical for optimizing the operation of such pipelines. This work aims to develop a dynamic computational model to simulate phosphate slurry flow in pipelines. The case study focuses on the OCP Group’s main slurry pipeline, which links the mining sites at Khouribga to the industrial plants at Jorf Lasfar, Morocco. This pipeline system spans a total length of 187.124 km, consisting of 5237 pipes with an inner diameter ranging from 0.8546 m to 0.8578 m, and features several elevation changes along its ground level. Using a section-averaged, dynamic approach and the Finite Volume scheme, the model computes essential flow parameters, including density, dynamic viscosity, and pressure, for the incompressible and non-Newtonian slurry and process water flows. The model’s accuracy is validated against on-site measured data, showing an average deviation of ±0.32% for outlet density, and below 10% for pressure along the pipeline, underscoring the model’s reliability. Additionally, a sensitivity analysis was conducted to illustrate the impact of key parameters on the predicted head losses and pressures along the pipeline. This analysis shows that the slurry viscosity is the most critical parameter, significantly influencing these predictions. This model provides high accuracy and reasonable CPU time for real-time simulation and monitoring, while also offering significant potential for optimizing pipeline operations and ensuring the reliability of phosphate transport.

Standing on Elevated Platform Changes Postural Reactive Responses during Arm Movement.

Background/Objectives: This study investigated the behavior of postural adjustments throughout the entire action: from the preparatory phase (anticipatory postural adjustment, APA), the focal movement phase (online postural adjustments, OPA), to the compensatory phase (compensatory postural adjustment, CPA) while raising the arms in a standing position, both with eyes opened and closed. The goal was to analyze the effects of reduced sensorial information and different heights on postural muscle activity during these three phases. Methods: Eight young women performed rapid shoulder flexion while standing on the ground and on a 1-m elevated platform. The EMG activity of the trunk and lower limb muscles was recorded during all three phases. Results: Although average muscle activity was similar on the ground and the elevated platform, the pattern of postural muscle activation varied across the motor action. During OPA, all postural muscle activity was the highest, while it was the lowest during APA. On the elevated platform postural muscles have increased their activation during APA. In the most stable condition (standing on the ground with eyes opened), muscle activity showed a negative correlation between APA and OPA, but there was no correlation between OPA and CPA. Conclusions: Our results suggest postural control adapts to sensory, motor, and cognitive conditions. Therefore, the increased demand for postural control due to the height of the support base demands greater flexibility in postural synergies and alters muscle activity.

Effects of Climate, Soil, Topography and Disturbance on Liana Prevalence.

Lianas (woody vines and climbing monocots) are increasing in abundance in many tropical forests with uncertain consequences for forest functioning and recovery following disturbances. At a global scale, these increases are likely driven by disturbances and climate change. Yet, our understanding of the environmental variables that drive liana prevalence at regional scales is incomplete and geographically biased towards Latin America. To address this gap, we present a comprehensive study evaluating the combined effects of climate, soil, disturbance and topography on liana prevalence in the Australian Wet Tropics. We established 31 20 × 20 m vegetation plots along an elevation gradient in low disturbance (canopy closure ≥ 75%) and high disturbance (canopy closure ≤ 25%) forest stands. In these plots, all tree and liana (defined as all woody dicot vines and climbing monocots, i.e., rattans) stems ≥ 1 cm DBH were measured and environmental data were collected on climate, soil and topography. Generalised linear models were used with multi-model averaging to quantify the relative effects of the environmental variables on measures of liana prevalence (liana-tree basal area ratio, woody vine basal area and stem density and rattan stem density). Liana prevalence decreased with elevation but increased with disturbance and mean annual precipitation. The increase in the liana-tree ratio with precipitation was more pronounced for highly disturbed sites. Like other tropical regions, disturbance is an important driver of liana prevalence in Australian rainforests and appears to interact with climate to increase liana-tree ratios. The observed increase in liana-tree ratio with precipitation contrasts findings from elsewhere but is confounded by correlated changes in elevation and temperature, which highlights the importance of regional studies. Our findings show that forests with high disturbance and climatic conditions favourable to lianas are where lianas most likely to outcompete trees and impede forest recovery.

Do Constrained Liners (in a 145° onlay implant) Provide Any Benefit? A Matched Retrospective Study

The purpose of this study was to compare the outcomes of primary reverse total shoulder arthroplasty (rTSA) using constrained liners (in a 145° onlay implant, Exactech, Equinoxe) with primary rTSA using standard liners with a minimum 1-year follow-up. A total of 836 primary rTSA patients were analyzed in this study. Patients treated with constrained liners (n=209) were cross-matched 1:3 for age, gender, glenosphere diameter, and follow-up duration, and compared with 627 patients who underwent primary rTSA with standard liners. Study endpoint was at one year. Outcomes were analyzed preoperatively and at the latest follow-up. Patient characteristics, postoperative range of motion (ROM), patient reported outcomes (PROs), complications and revisions were recorded. There was no statistically significant changes in improvement in pain (-4.9 vs -5.1; p=0.356), ROM (abduction, 45.7° vs 47.9°; p=0.522) (forward elevation, 44.0 vs 50.8°; p=0.057) (internal rotation score 1.0 vs 1.1; p=0.709) (external rotation, 17.9° vs 16.7°; p=0.543), or PROs (American Shoulder and Elbow Surgeons Score, 44.5 vs 43.7; p=0.107) (Shoulder Arthroplasty Smart score, 27.5 vs 30.0; p=0.052) between the constrained and standard liner cohorts at minimum 1 year follow-up. However, the constrained liner rTSA cohort had a significantly higher rate of adverse events (6.2% vs. 2.7%; p=0.012), including a higher rate of scapular notching (15.6% vs. 8.8%; p=0.015). The utilization of constrained liners in primary rTSA demonstrated no significant difference in the change in pain, abduction, forward elevation, ER and IR scores, ASES scores, and SAS scores at minimum 1-year follow-up. There was no significant difference in forward elevation or abduction compared to standard liners. However, we observed that the overall rate of adverse events, including scapular notching were significantly higher in the constrained liner cohort. Long-term clinical and radiographic follow-up is necessary to fully elucidate the durability of these results. At this time, it is unclear if constrained liners have any benefit in rTSA.

Optimal triage of patients with acute chest pain.

Acute chest pain (ACP) is one of the most common symptoms in patients admitted to emergency departments (ED). It can be related to several life-threatening cardiovascular conditions such as acute coronary syndrome (ACS), aortic dissection, and pulmonary embolism. The optimal triage of patients with ACP is a clinical and healthcare necessity given the large number of patients daily admitted to ED with this symptom. The first contact with the patient in ED includes the clinical appraisal of the characteristics of ACP and coexisting symptoms, and the assessment of the patient's medical history. Risk scores may help stratify a patient's likelihood of having cardiac chest pain. The ECG examination allows the identification of patients with ST-segment elevation, depression, or T-wave changes, but may be normal in patients with non-ST-segment elevation ACS. Rapid protocols based on serial high-sensitivity cardiac troponin assays within one or two hours are recommended for identifying candidates for early discharge. Due to the bedside feasibility, non-invasiveness, and wide availability, transthoracic echocardiography represents the first-line imaging modality for evaluating patients with ACP. In selected cases, computed tomography angiography may also be performed. A practical approach to ACP in ED should improve patient outcomes and reduce healthcare system costs. This review aimed to provide an overview of the characteristics of patients with ACP of cardiac origin and to describe the state of the art about their management in the ED.

The impact of a storm on the microtidal flat in the Yellow River Delta

Strong hydrodynamic forces generated by storms are key in shaping coastal tidal flats. Most tidal flats achieve equilibrium by adapting to hydrodynamic conditions and sediment inputs. However, high-energy wave activity during storms disrupts this equilibrium, causing rapid and significant changes, particularly in tidal flats, especially in microtidal flats, which are characterized by low tidal ranges. In this study, we conducted an 11-d field campaign on a microtidal flat in the Yellow River Delta (YRD), capturing data during both stormy and calm weather conditions. We measured tidal currents, wave activity, suspended sediment concentrations and sediment grain sizes. The results demonstrated that the tidal flat maintained equilibrium under calm conditions, with minimal fluctuations in bed level (within ±2 mm). Contrastingly, severe erosion and sediment removal during the storm significantly altered the equilibrium of the area. The storm-induced high shear stresses, ranging from 1.02 to 1.48 , along with alongshore sediment transport, resulted in an elevation change of -10 mm. Furthermore, the subsequent bed level recovery was minimal and insufficient to offset the erosion. Compared to that of the mesotidal and macrotidal flats, post-storm recovery on microtidal flats was limited due to shorter inundation periods and weaker hydrodynamic forces. Therefore, frequent storms may lead to continuous shoreline retreat on microtidal coasts. Conclusively, the present findings underscore the significant impact of storm-induced erosion on the evolutionary processes of microtidal flats and suggest that greater attention should be given to protecting these areas during storms in the Yellow River Delta. The insights can guide the development of more effective coastal protection strategies, highlighting the need for enhanced measures to mitigate erosion and promote resilience in microtidal regions.

Dynamics and internal structure of a rock glacier: Inferring relationships from the combined use of differential synthetic aperture radar interferometry, electrical resistivity tomography and ground‐penetrating radar

AbstractRock glaciers are characteristic landforms in alpine environments originating from the movement of permanently frozen ground. Hereby, rock glacier velocity (RGV) is an important parameter for understanding the effects of climate change on mountain permafrost. Although understanding of rock glacier dynamics has increased during the last decades, linking small‐scale surface kinematics to sub‐surface properties and heterogeneities remains a challenge. To address this gap, we conducted geophysical surveys (electrical resistivity tomography [ERT] and ground‐penetrating radar [GPR]) along two profile lines of 450 and 950 m in length on a rock glacier in the Central Swiss Alps. Additionally, RGV was derived from Sentinel‐1 differential synthetic aperture radar interferometry (DInSAR) to quantify annual east–west displacement and elevation change as well as seasonal acceleration during the snow‐free summer months with a ground sampling distance of 5 m. Our results show that movement angle and seasonality are highly associated with different patterns in sub‐surface structure. These different movement patterns are linked to subunits of different morphological origins. Thereby, we can upscale the geophysical results based on the DInSAR surface movement parameters and outline an area within the study site probably affected by ice of glacial origin. Hence, DInSAR movement angle and seasonality can help to bring local sub‐surface information derived from time‐consuming geophysical investigations into the spatial domain. In this way, a better understanding of the current morphodynamics as well as the past and future evolution of the landform can be reached. Applying the approach to other sites with available geophysical investigations could enhance our knowledge about systematic links between surface kinematics and the internal structure of rock glaciers and other ice‐rich glacial and peri‐glacial landforms, as well as their response to a warming climate.

Deriving seasonal and annual surface mass balance for debris-covered glaciers from flow-corrected satellite stereo DEM time series

Abstract Glaciers in High-Mountain Asia are experiencing varying rates and patterns of mass loss due to a complex interplay between glacier surface processes, local conditions and climate forcing. Spatially distributed surface mass balance (SMB) estimates can provide valuable insight into these drivers, but observations are currently limited in both space and time. We used very-high-resolution optical stereo images acquired by commercial satellites to prepare time series of digital elevation models (DEMs), and derived contemporaneous surface velocity and elevation change products for six debris-covered glaciers in Nepal. We developed new methods to produce flow-corrected Lagrangian SMB maps to isolate local surface ablation signals with enough detail to study individual ice cliffs. Our results show reduced ablation under thick debris cover and enhanced ablation over ice cliffs. Ablating ice cliffs were responsible for $10\!-\!38\%$ of the total ablation over debris-covered areas, even though they covered $\leq \!11\%$ of the total area. Seasonal SMB products reveal the timing and patterns of summer accumulation and ablation, underscoring the importance of snow avalanches for low-elevation debris-covered glaciers in the region. Our approach can be applied to other glaciers with repeat high-resolution DEM coverage and extended for regional analyses of SMB on seasonal to interannual timescales.

Analyses of sea turtle landing behavior based on frequently observed coastal profile data - A case study in Enshu Coast, Japan

This study analyses sea turtle landing behavior along a 10 km sandy beach on the Enshu Coast, Japan, facing the Pacific Ocean. Data for the analysis are sea turtles' landing positions and crawl tracks recorded by a handheld GNSS device from May to September (2011–2016), noting spawning or no-spawning activity simultaneously, supplemented by weekly cross-shore beach profiles surveyed at four locations, satellite images, and other geographical data. At the onset, landing positions on the beach are visualized to determine local concentrations along the beach. Subsequently, we estimate the distance of spawning and no-spawning positions from the waterline during landing and evaluate beach stability through the temporal elevation change standard deviation. The study found that preferred spawning locations are 40–70 m from the waterline, above the intertidal zone, on bare sand, with a standard deviation of 0.1–0.6 m. This study also highlights the impact of beach infrastructure on sea turtle spawning failures and the influence of significant wave height on sea turtle landing.

Gene expression plasticity in response to rapid and extreme elevation changes in Perdix hodgsoniae (Tibetan Partridge)

Abstract Phenotypic plasticity is a vital biological process facilitating the persistence of organisms amid rapid environmental changes. Investigating the genetic basis of plastic traits necessitates transplantation experiments, but much of the existing research has focused on laboratory model systems. Transplant experiments in the wild may provide better understanding of how plasticity operates in the context of real-world challenges. However, performing transplantation experiments in non-model systems, such as birds, could be challenging. In this study, we aim to develop Perdix hodgsoniae (Tibetan Partridge) inhabiting the highlands of the Tibetan Plateau as a suitable system to study genetic basis underlying short-term plastic response to rapid changes in elevation. We did a first attempt of field-based transplantation experiment by exposing P. hodgsoniae individuals to extreme change in elevation from their native elevation (3,623 m) to a low elevation outside their natural distribution range (500 m). We compared changes in gene expression in these birds at different time points, pre-transplant (Day 0), and post-transplant (Day 3 and Day 22). The birds successfully survived transplantation and exhibited well-being after 22 days. We identified a total of 715 differentially expressed genes (DEGs) across these 3 time points. Our analysis revealed a genome-wide decrease in expression following the transplantation, indicating that the birds possibly exhibited stress-induced transcriptional attenuation (SITA) because of the extreme change in elevation, suggesting a broader response at the transcriptional level, possibly as a mechanism to cope with extreme changes in the environment. Our analysis further suggested that heat stress posed an immediate challenge for the birds following the transplant, as we identified changes in expression in many genes associated with heat stress response. Our findings affirm the viability of conducting transplant experiments in the P. hodgsoniae and provides initial insights into gene expression changes associated with the plastic response to rapid changes in elevation in these birds.

How well can satellite altimetry and firn models resolve Antarctic firn thickness variations?

Abstract. Elevation changes of the Antarctic Ice Sheet (AIS) related to surface mass balance and firn processes vary strongly in space and time. Their subdecadal natural variability is large and hampers the detection of long-term climate trends. Firn models or satellite altimetry observations are typically used to investigate such firn thickness changes. However, there is a large spread among firn models. Further, they do not fully explain observed firn thickness changes, especially on smaller spatial scales. Reconciled firn thickness variations will facilitate the detection of long-term trends from satellite altimetry; the resolution of the spatial patterns of such trends; and, hence, their attribution to the underlying mechanisms. This study has two objectives. First, we quantify interannual Antarctic firn thickness variations on a 10 km grid scale. Second, we characterise errors in both the altimetry products and firn models. To achieve this, we jointly analyse satellite altimetry and firn modelling results in time and space. We use the timing of firn thickness variations from firn models and the satellite-observed amplitude of these variations to generate a combined product (“adjusted firn thickness variations”) over the AIS for 1992–2017. The combined product characterises spatially resolved variations better than either firn models alone or altimetry alone. It provides a higher resolution and a more precise spatial distribution of the variations compared to model-only solutions and eliminates most of the altimetry errors compared to altimetry-only solutions. Relative uncertainties in basin-mean time series of the adjusted firn thickness variations range from 20 % to 108 %. At the grid cell level, relative uncertainties are higher, with median values per basin in the range of 54 % to 186 %. This is due to the uncertainties in the large and very dry areas of central East Antarctica, especially over large megadune fields, where the low signal-to-noise ratio poses a challenge for both models and altimetry to resolve firn thickness variations. A large part of the variance in the altimetric time series is not explained by the adjusted firn thickness variations. Analysis of the altimetric residuals indicate that they contain firn model errors, such as firn signals not captured by the models, and altimetry errors, such as time-variable radar penetration effects and errors in intermission calibration. This highlights the need for improvements in firn modelling and altimetry analysis.