Elevation Changes Research Articles

Development of an Underwater Adaptive Penetration System for In Situ Monitoring of Marine Engineering Geology.

In recent years, offshore wind farms have frequently encountered engineering geological disasters such as seabed liquefaction and scouring. Consequently, in situ monitoring has become essential for the safe siting, construction, and operation of these installations. Current technologies are hampered by limitations in single-parameter monitoring and insufficient probe-penetration depth, hindering comprehensive multi-parameter dynamic monitoring of seabed sediments. To address these challenges, we propose a foldable multi-sensor probe and establish an underwater adaptive continuous penetration system capable of concurrently measuring seabed elevation changes and sediment pore water pressure profiles. The reliability of the equipment design is confirmed through static analysis of the frame structure and sealed cabin. Furthermore, laboratory tests validate the stability and accuracy of the electrical and mechanical sensor measurements. Preliminary tests conducted in a harbor environment demonstrate the system's effectiveness.

Multiple sources of elevation change during and after the 2011–2012 Cordón Caulle, Chile eruption measured by satellite topographic time series

The 2011–2012 eruption at Cordón Caulle, Chile offers an exceptional opportunity to investigate topographic evolution of a laccolith, lava flows, and tephra during and after rhyolitic eruptions using satellite TanDEM-X and Plèiades data. We find distinct phases: rapid surface uplift from the laccolith and tephra (June–August 2011) and lava (June 2011–March 2012), followed by a reduction in the elevation of the laccolith and tephra (up to 19 m yr−1) until February 2013, and slower subsidence of all deposits until 2019 (the most recent data). The spatial distribution of subsidence-to-uplift ratios shows different volcanic and geomorphological processes occurring (degassing, cooling, crystallization, lateral movement, compaction, erosion). Pre-eruptive river channels showed elevation increases of up to 10–50 m due to tephra deposition, but this tephra was largely removed within three to four years. This research shows the potential of repeating high-resolution remote sensing elevation data to elucidate volcanic landscape evolution and yields insights into the co- and post-eruptive evolution of deposits.

Decursin ameliorates neurotoxicity induced by glutamate through restraining ferroptosis by up-regulating FTH1 in SH-SY5Y neuroblastoma cells

Alzheimer’s disease (AD) is the most common form of neurodegeneration which currently has no effective treatment. Ferroptosis is a new style of programmed cell death and is widely implicated in the pathogenesis and progression of AD. Decursin has been shown widely neuroprotective effects but poorly understood about the underlying mechanisms between decursin and ferroptosis in AD. Here, the protective effect of decursin and the underlying mechanism under glutamate treatment in SH-SY5Y cells was investigated. SH-SY5Y cells were cultured with glutamate in the presence or absence of decursin. The safe concentrations of decursin on SH-SY5Y cells were measured via CCK-8. Furthermore, LDH content, antioxidant enzyme activities including GPx, CAT and SOD, MDA contents, GSH levels, ROS formation, MMP, mitochondria ultrastructure morphology change, and intracellular Fe2+ levels were measured to investigate the influence of decursin and Fer-1 on ferroptosis in glutamate-treated SH-SY5Y cells. Moreover, the expressions of ferroptosis-related proteins were determined by Western blot. As a result, glutamate-induced cell survival was markedly elevated and morphological change was improved by decursin administrated in SH-SY5Y cells. Furthermore, decursin could reversed the decreased antioxidant enzyme activities, GSH levels, GPX4n and FTH1 expression, as well as the increased iron levels, LDH, MDA, ROS formation, and MMP, which showed similar effects to Fer-1, the specific ferroptosis inhibitor. Therefore, the inhibitory effect of decursin on ferroptosis probably was partially governed by FTH1 expression to regulate the cellular iron homeostasis. Additionally, decursin facilitated the translocation of Nrf2 from the cytoplasm to the nucleus. Taken together, our data for the first time suggest that decursin could ameliorate neurotoxicity induced by glutamate by attenuating ferroptosis via alleviating cellular iron levels by up-regulating FTH1 expression which is attributing to its promotion of Nrf2 translocation into the nucleus in SH-SY5Y neuroblastoma cells. Hence, decursin might be a novel and promising therapeutic option for AD. In addition, our study also provided some new clues to potential target for the intervention and therapy of AD.

Climate tracking by mountain bumblebees across a century: Distribution retreats, small refugia and elevational shifts

Cold-adapted species endangered by global change are crucial cases for understanding range dynamics and its interface with conservation and environmental decision-making. However, the study of their distribution change is either neglected or conducted at coarse resolutions at continental level, thus having little indicator value for regional and local conservation strategies. In view of climate change, it can be expected that cold-adapted insects should reduce distribution ranges by mainly concentric retreats and moving uphill. To test these hypotheses, we targeted four threatened, high-altitude bumblebees differing in subgenera and elevation ranges, and covering the main central and south European mountains. We performed species distribution models including climate and habitat at a 1 km-resolution, and we estimated elevation uphill and the year of elevation change with broken-line regressions. Results indicate that climate change will likely cause severe future range contractions across large areas, more in the Apennines (80 %–85 % ca) than the Alps and Pyrenees (24–56 % ca), with mostly concentric retreats as future extents will nearly entirely be included in the present ones. Remarkably, since the ‘80 s elevation uplift has started by about 325–535 m, a period coinciding with the beginning of the main warming, and will continue. The size and distribution of climate refugia will challenge conservation: they will be small (2–60 % of current areas) and even vary regionally, but while in the Apennines and Pyrenees they will be nearly entirely within Protected Areas, only a third will be so for the Alps. Such impressive distribution and elevation changes demonstrate that cold-adapted bumblebees can track climate change, reasons for it to be found in the specialist niches mainly requiring narrow temperature ranges and glacier presence. Overall, the distribution changes of cold specialist bumblebees driven by climate change demonstrate that conservation and policy makers should act upon the time dynamics and regional responses because future range contraction, the little availability of new areas and the movement uphill emerge as consistent patterns.

Microtopographic response of tilled loess slopes during stages of water erosion development

The tilled slopes in the loess region are characterized by artificial management practices that result in variations in microtopography, which serve as both the site of water erosion and a significant factor contributing to further slope erosion development. However, the response of microtopography during the process of erosion development on tilled loess slopes is unclear. In this study, artificial rainfall simulations were conducted to simulate the development of water erosion (splash erosion (SpE), sheet erosion (ShE), and rill erosion (RE)) under three slope gradients (5°, 10°, and 20°) and three tillage practices (artificial backhoe (AB), artificial digging (AD), and contour tillage (CT)) at a rainfall intensity of 60 mm h−1. The spatial correlation and heterogeneity of the microtopography were analysed using semivariogram functions and fractal dimensions. The response characteristics of microtopography during the water erosion development process on tilled loess slopes were analysed from three perspectives: microtopography factors, erosion equilibrium areas, and slope strips M-ΔDEM. The results indicated that the microtopography process data exhibited moderate to high spatial autocorrelation. There is a positive correlation between microtopographic factors and the slope gradient. Tilled slopes exhibit erosion equilibrium effects during the processes of splash erosion, sheet erosion, and rill erosion. These equilibrium effects are located in the longitudinal ranges of 700 to 1200 mm, 700 to 1300 mm, and 800 to 1100 mm, respectively. Soil erosion and deposition primarily occur in the middle and lower parts of the slope, with 70 % of the slope’s elevation changing within 10 mm, while the remaining changes can reach 25 mm. Among the three tillage practices, AB is the most susceptible to slope influences, which can lead to soil loss, and an optimal slope gradient exists for implementing AB measures. In the case of CT at a slope of 20°, ridge breaking is more likely to occur, but considering the combined effects of soil loss suppression and the difficulty in forming rills, it is recommended to prioritize CT as the preferred tillage practice among the three practices. This study can provide a theoretical foundation for understanding the mechanisms through which microtopography influences water erosion. Additionally, it can serve as a theoretical basis for calibrating parameters in soil erosion models for sloping cultivated lands.

Redistribution of debris‐flow sediment following severe wildfire and floods in the Jemez Mountains, New Mexico, USA

AbstractSevere fire on steep slopes increases stormwater runoff and the occurrence of runoff‐initiated debris flows. Predicting locations of debris flows and their downstream effects on trunk streams requires watershed‐scale high‐resolution topographic data. Intense precipitation in July and September 2013 following the June 2011 Las Conchas Fire in the Jemez Mountains, New Mexico, led to widespread debris flows in the watershed of Rito de los Frijoles. We differenced lidar Digital Elevation Models (DEMs) collected in 2010 and 2016 to map subwatersheds experiencing debris flows and changes in elevation of the trunk stream. Debris flow occurrence was well predicted by previous assessments of debris‐flow hazard; debris flows occurred in 7 of 9 sub‐basins where the debris‐flow hazard was above 60% for the 25‐year rainfall event, and in 0 of 21 basins where debris flow hazard was less than 60%. Debris flows resulted in fan deposition at the confluence with the trunk stream followed by transport during three documented floods. The bed of the 22 km trunk stream increased in elevation by a mean of 0.29 m, but the local change in thalweg elevation was controlled by inputs of water and sediment and longitudinal variation in gradient. Downstream of the mouths of tributaries with debris flows, the thalweg of the trunk stream rose as much as 2 m. Downstream of the mouths of tributaries without debris flows the thalweg of the main stem degraded by as much as 2 m, mobilizing sediment that was then deposited further downstream where the gradient of the trunk stream decreases. In conclusion, the transport of sediment generated by debris flows was predictably related to spatial variation in sediment supply, discharge and gradient.

Resistance and resilience: Tidal freshwater marsh response and recovery to acute and chronic saltwater intrusion

The ability to both resist and recover from disturbances like storm surge and saltwater intrusion plays a key role in shaping the structure and function of tidal marshes. In this study, porewater chemistry, vegetation, and soil elevation change were measured in field plots of a tidal freshwater marsh exposed to four years of experimental press (chronic) and pulse (acute) brackish water additions followed by five years of recovery to assess their resistance and resilience to saltwater intrusion. Press additions produced significant, widespread changes in marsh structure and function including increased porewater N and P, reduced macrophyte cover and species richness, and loss of soil surface elevation whereas pulse additions had little effect. Once dosing ceased, porewater chemistry, vegetation and soils in press plots recovered at differing rates, with porewater N and P declining to background levels after one year, plant cover and species richness increasing within two to four years, and soil surface elevation increasing to similar levels found in control plots after five years. The plant community in the press treatment converged with the other treatments after 3–4 years, though macrophyte species exhibited varying rates of recovery. Ground cover (Ludwigia repens) and soft stem species (Persicaria) that declined first, recovered faster than Zizaniopsis miliacea that was more resistant but less resilient to brackish water intrusion. While tidal freshwater marshes are resistant and resilient to pulses such as those that stem from hurricanes and storm surges, continued long-term intrusion events like sea level rise (SLR) will likely lead to conversion into brackish marsh. Understanding long-term responses and tradeoffs in resistance and recovery as shown in this experiment offers insight into the future trajectory of tidal freshwater marshes as well as broader ecosystem responses to disturbance and recovery crucial to management and restoration.

Climate factors dominate the elevational variation in grassland plant resource utilization strategies.

Specific leaf area (SLA) and leaf dry matter content (LDMC) are key leaf functional traits often used to reflect plant resource utilization strategies and predict plant responses to environmental changes. In general, grassland plants at different elevations exhibit varying survival strategies. However, it remains unclear how grassland plants adapt to changes in elevation and their driving factors. To address this issue, we utilized SLA and LDMC data of grassland plants from 223 study sites at different elevations in China, along with climate and soil data, to investigate variations in resource utilization strategies of grassland plants along different elevational gradients and their dominant influencing factors employing linear mixed-effects models, variance partitioning method, piecewise Structural Equation Modeling, etc. The results show that with increasing elevation, SLA significantly decreases, and LDMC significantly increases (P < 0.001). This indicates different resource utilization strategies of grassland plants across elevation gradients, transitioning from a "faster investment-return" at lower elevations to a "slower investment-return" at higher elevations. Across different elevation gradients, climatic factors are the main factors affecting grassland plant resource utilization strategies, with soil nutrient factors also playing a non-negligible coordinating role. Among these, mean annual precipitation and hottest month mean temperature are key climatic factors influencing SLA of grassland plants, explaining 28.94% and 23.88% of SLA variation, respectively. The key factors affecting LDMC of grassland plants are mainly hottest month mean temperature and soil phosphorus content, with relative importance of 24.24% and 20.27%, respectively. Additionally, the direct effect of elevation on grassland plant resource utilization strategies is greater than its indirect effect (through influencing climatic and soil nutrient factors). These findings emphasize the substantive impact of elevation on grassland plant resource utilization strategies and have important ecological value for grassland management and protection under global change.

Assessment of Nutritional Practices of Mountain Runners before and during Competitions.

Mountain running, distinct from traditional road running, involves natural trails with significant elevation changes. This study aims to analyze dietary and supplementation practices among advanced and elite Polish mountain runners. Conducted from May to October 2023, this study included 36 participants (13 women, 23 men) aged 21-43 years. A custom questionnaire assessed nutrition two days before and during a competition, focusing on macronutrient intake, hydration, and supplementation. Statistical analyses were performed to compare advanced and elite athletes. Participants consumed an average of 3164.14 kcal two days before and 3176.97 kcal the day before the competition. Carbohydrate intake averaged 7.69 g/kg two days before and 7.64 g/kg the day before the race, potentially insufficient for optimal glycogen stores. Protein intake was adequate, averaging 1.63 g/kg two days before and 1.73 g/kg the day before the race. Fluid intake averaged 2811.25 mL two days before and 2891.80 mL the day before the race. During races, carbohydrate intake averaged 58.56 g/h, with variations based on race duration. Most participants used isotonic drinks and water for hydration. Mountain runners generally adhere to proper nutrition guidelines, with adequate protein and fluid intake. However, their carbohydrate intake may be insufficient for longer races. Higher carbohydrate intake during exercise could provide additional benefits.

Header Height Detection and Terrain-Adaptive Control Strategy Using Area Array LiDAR

During the operation of combine harvesters, the cutting platform height is typically controlled using manual valve hydraulic systems, which can result in issues such as delays in adjustment and high labor intensity, affecting both the quality and efficiency of the operation. There is an urgent need to enhance the automation level. Conventional methods frequently employ single-point measurements and lack extensive area coverage, which means their results do not fully represent the terrain’s variations in the area and are prone to local anomalies. Given the inherently undulating terrain of farmland during harvesting, a control strategy that does not adjust for minor undulations but only for significant ones proves to be more rational. To this end, a sine wave superposition model was established to simulate three-dimensional ground elevation changes, and an area array LiDAR was used to collect 8 × 8 data for the header height. The effects of mounds and stubble on the measurement results were analyzed, and a dynamic process simulation model for the solenoid valve core was developed to analyze the on/off delay characteristics of a three-position four-way electromagnetic directional valve. Moreover, a physical model of the hydraulic system was constructed based on the Simscape module in Simulink, and the Bang Bang switch predictive control system based on position threshold was introduced to achieve early switching of the electromagnetic directional valve circuit. In addition, an automatic control system for cutting platform height was designed based on an STM32 microcontroller. The control system was tested on the hydraulic automatic control test rig developed by Shanxi Agricultural University. The simulation and experimental results demonstrated that the control system and strategy were robust to output disturbances, effectively enhancing the intelligence and environmental adaptability of agricultural machinery operations.

Safety assessment of coronary arteries during left bundle branch area pacing.

This study aimed to assess the safety of left bundle branch area pacing (LBBAP) by measuring the distance from the tip of the electrode to the nearby coronary artery with anine-partition grid method. From January 2019 to October 2020, patients who underwent LBBAP and postoperative coronary angiography in the Second Affiliated Hospital of Nanchang University were included in the study. The patients' fluoroscopic images of LBBAP and coronary angiography were collected and analyzed. Changes in the ST‑T segment in the electrocardiogram (ECG), serum troponin, and myocardial enzyme profiles were observed before and after the LBBAP procedure. Atotal of 50patients were included in this study, of whom 46patients underwent implantation with apacemaker and 4patients received an implantable cardioverter defibrillator (ICD). The pacing electrodes were confined to the posterior-middle (PM), median (M), Posterior inferior (PI), and middle inferior (MI) positions of the two-dimensional nine-square grid or in the junction area of the above positions, and were concentrated in the rectangle formed by the line of the center points of the four positions. The average vertical distances from the electrode tip to the left anterior descending branch artery (LAD), posterior descending branches (PD) and the left posterior ventricular branches (PL) were 19.69 ± 8.72 mm, 26.09 ± 8.02 mm, and 21.11 ± 7.86 mm, respectively; the minimum was 5.28 mm, 9.51 mm, and 8.69 mm, respectively. Coronary angiography in all patients showed no significant injury to the ventricular septal branch; however, we observed elevated serum troponin and changes in ST‑T segment in ECG. The study demonstrates that pacing electrodes in LBBAP can be safely implanted over awide range. Coronary arteries are likely to be safe when the pacing electrodes are located within the rectangle formed by the line connecting the PM, M, PI, and MI zone centroids. The left bundle branch can be quickly captured and the safety of the coronary artery can be improved by locating the electrode in the posterior-mid zone. The potential risk of injury to the LAD from the electrode is greater compared with the PD.

Land surface response to groundwater drawdown and recovery in Taiyuan city, Northern China, analyzed with a long-term elevation change measurements from leveling and multi-sensor InSAR

In recent years, a comprehensive program of groundwater management was adopted in Taiyuan city, Northern China, with the aim to prevent the lowering of groundwater level and manage land subsidence due to excessive groundwater pumping in the past decades. Groundwater recovery has been observed in this city following the termination of groundwater pumping. While the link between land subsidence and groundwater pumping is well documented, how the land surface responds to the recovery of groundwater has not been studied in detail. In this study, we analyzed the leveling data from 1956 to 2000 to investigate changes in ground elevation in response to groundwater drawdown prior to the termination of groundwater pumping and combined them with InSAR (Interferometric Synthetic Aperture Radar) displacement data during 2003–2020 to evaluate the effect of groundwater recharge after the termination of groundwater pumping. A method was proposed to merge InSAR time series of displacement derived from multiple satellites (ENVISAT, COSMO-SkyMed, TerraSAR-X, and Sentinel-1) to achieve a consistent, long-term continuous deformation. We found that previous groundwater depression cones in Taiyuan (Xizhang, Wanbailin, Wujiabao, and Xiayuan) have turned into groundwater recovery and the corresponding subsidence centers have switched to land uplift. The subsidence center of Xizhang, north of Taiyuan city, experienced a total subsidence of 749 mm by Aug 2003; it then turned into uplift with an amount of rebound of 9.2 % of previous subsidence by the end of 2020. In central area of Taiyuan, the cumulated subsidence is 1127 mm in Wanbailin, 1817 mm in Xiayuan, and 3343 mm in Wujiabao. Beginning in Aug 2010, they all turned into land uplift, with a rebound of 7.9 %, 4.8 % and 3.6 % of the previous subsidence in each center, respectively. An analysis of the correlation between groundwater level and ground displacement suggests that the ground uplift is related to the poro-elastic rebound mechanism in the porous aquifer system, which is caused by the rise in pore pressure with groundwater recovery, and the amount of subsidence/uplift is controlled by the stratigraphic properties. The adverse impacts on the built environment due to the rising groundwater level were discussed. The findings improve our understanding of anthropogenic ground deformation in complex urban aquifers influenced by groundwater pumping and recharge and provides essential information that can contribute to future groundwater management and groundwater-related hazard mitigation over the Taiyuan city.

The mitochondrial genome of Bottapotamon fukienense (Brachiura: Potamidae) is fragmented into two chromosomes

BackgroundChina is the hotspot of global freshwater crab diversity, but their wild populations are facing severe pressures associated with anthropogenic factors, necessitating the need to map their taxonomic and genetic diversity and design conservation policies.ResultsHerein, we sequenced the mitochondrial genome of a Chinese freshwater crab species Bottapotamon fukienense, and found that it is fragmented into two chromosomes. We confirmed that fragmentation was not limited to a single specimen or population. Chromosome 1 comprised 15,111 base pairs (bp) and there were 26 genes and one pseudogene (pseudo-nad1) encoded on it. Chromosome 2 comprised 8,173 bp and there were 12 genes and two pseudogenes (pseudo-trnL2 and pseudo-rrnL) encoded on it. Combined, they comprise the largest mitogenome (23,284 bp) among the Potamidae. Bottapotamon was the only genus in the Potamidae dataset exhibiting rearrangements of protein-coding genes. Bottapotamon fukienense exhibited average rates of sequence evolution in the dataset and did not differ in selection pressures from the remaining Potamidae.ConclusionsThis is the first experimentally confirmed fragmentation of a mitogenome in crustaceans. While the mitogenome of B. fukienense exhibited multiple signs of elevated mitogenomic architecture evolution rates, including the exceptionally large size, duplicated genes, pseudogenisation, rearrangements of protein-coding genes, and fragmentation, there is no evidence that this is matched by elevated sequence evolutionary rates or changes in selection pressures.

Holocene thinning in central Greenland controlled by the Northeast Greenland Ice Stream

Ice-core records from the interior of the Greenland ice sheet suggest widespread thinning during the Holocene. However, the recurring underestimation of this thinning in numerical models raises concerns about both the veracity of such reconstructions and the reliability of glaciological models. Recent work suggests the 8000-year-old Northeast Greenland Ice Stream (NEGIS), including a now-extinct northern tributary, may have been an early influence on Greenland ice-sheet dynamics. Yet, the inaccurate reproduction of NEGIS-like dynamics in most models hampers investigation of whether this feature played a role in Holocene ice-sheet thinning. Here we show that grounding-line retreat in northeast Greenland triggers elevation changes at the northern summit via ice-dynamic effects modulated by the paleo NEGIS system. In our simulations, fast ice-stream flow caused by transiently imposed reduced basal shear stress following the northeast retreat explains 55% ( ± 18%) of the estimated ice thinning, showing that ice-stream dynamics is one of the main drivers of the NGRIP Holocene surface elevation drop. Our findings show that the ice-flow in northeast Greenland plays a large role in ice-surface elevation changes in central Greenland.

Skill assessment of a total water level and coastal change forecast during the landfall of a hurricane

The Total Water Level and Coastal Change Forecast (TWL&CC Forecast) provides coastal communities with 6-day notice of potential elevated water levels and coastal change (i.e., dune erosion, overwash, or inundation) on sandy beaches that threatens safety, infrastructure, or resources. This continuously operating model provides hourly information for select regions along U.S. Gulf of Mexico and Atlantic Ocean coastlines. The objective of this work is to assess the skill of forecasts during a period of elevated water levels along the coasts of North Carolina (NC) and South Carolina, USA caused by Hurricane Isaias in August 2020, using a combination of observations and model hindcasts. Water levels and waves were observed throughout the storm at three locations near Wrightsville Beach, NC, which provided information to assess forecast skill; a wave buoy offshore, a tide gage at a local pier, and a pressure sensor deployed at the pier. In addition to observations, the non-hydrostatic phase-resolving model SWASH (Simulating WAves till SHore) was forced with hourly wave energy spectra derived from a coupled Delft3D-SWAN simulation during the peak of Isaias, to complement observations by computing nearshore wave height and wave-induced setup and runup at the shoreline. During the storm peak, SWASH-simulated water levels at the sensor position were comparable to those at the maximum landward extent (bias = −0.05 m; gain = 0.26; r2 = 0.99), suggesting that observations at the USGS sensor location were a useful proxy for total water level (TWL; sum of tide, surge and wave runup) at the shoreline that are predicted by the TWL&CC Forecast. The TWL forecast at Wrightsville Beach was consistent with observations from the USGS sensor (bias = −0.38 m and −0.74 m, scatter index = 0.22 and 0.28 for the two forecast model grids considered, respectively; weighted regression considering model uncertainty explained 95 percent of variability in observed TWL). Observed TWL was within the confidence interval of the TWL&CC Forecast for the 5 h at the storm peak. Forecast mean water levels (MWL; sum of tide, surge and wave setup) and tide gage observations were also consistent (bias = 0.07 m and 0.02 m for the forecast model grids; scatter index = 0.46; r2 = 0.80). Forecast MWL at the storm peak was within 0.06 m of the observed MWL from the tide gage for both sites. In the region where Isaias made landfall, eight additional pressure sensors were compared to the peak TWL forecast (bias = 0.14 m; scatter index = 0.18). Forecast TWL explained 90 percent of observed variability in TWL when considering uncertainty of the forecast with a weighted regression. The results demonstrate that wave-driven water levels contributed a significant portion of the forecast TWL during Isaias (52 percent during the three peak hours of the storm), and that TWL were represented using the forecast model. Mean absolute error of the coastal change forecast and observed overwash is 0.4 and 0.14 for the two forecast model grids considered. The skill demonstrated by this computationally efficient method indicates that the forecasting system can provide fast and reliable predictions of TWL across hundreds of km of coastline at sub-km resolution, days to hours in advance of when storms threaten coastal regions.

Incorporating Measurements of Vertical Land Motion in Wetland Surface Elevation Change Analyses

Incorporating Measurements of Vertical Land Motion in Wetland Surface Elevation Change Analyses

Elevation dependent change in ERA5 precipitation and its extremes

Mountain regions are recognised as hot-spots of climate change. Although the existence of an Elevation-Dependent Warming has been extensively confirmed in several mountain areas of the globe, fewer studies have analysed the elevational stratification of temporal trends of other climate variables, and particularly for precipitation. This study analyses changes in mean precipitation and its extremes in ERA5 global reanalysis data in key mountain areas of the globe, along with their elevational dependence, from 1951 to 2020. These include the Tibetan Plateau, the US Rocky Mountains, the Greater Alpine Region, and the Andes, as representative of different latitudes and climatic influences. Our analysis reveals common patterns of elevational dependent change in precipitation and its extremes in most of the mountainous areas, which emerge beyond their geographical differences. A positive elevational gradient of trends of extreme precipitation indices is found in the Tibetan Plateau, the Greater Alpine Region, and the subtropical Andes, highlighting a wetting effect (positive trends) at very high elevations. In contrast, the Rocky Mountains exhibit a negative elevational gradient, with a drying effect (negative trends) increasing with the elevation. Notably, a simple linear regression proved to be effective to describe the stratification of change in the Greater Alpine Region and the Rocky Mountains, whereas more complex vertical patterns need to be considered for the Andes and the Tibetan Plateau. Mean precipitation, heavy (≥\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ge$$\\end{document}10 mm) precipitation and the length of consecutive wet days show a consistent elevation-dependent stratification within each of the study areas, suggesting possible common driving mechanisms.

Autobiography: A 50-Year Quest for Understanding in Geoscience

Readers will be led down a random path from continental dynamics to paleoclimate. A key to understanding continental dynamics is recognizing that differences in gravitational potential energy per unit area between high and low terrain govern much of large-scale continental deformation. Removal of mantle lithosphere, not just crustal thickening, plays a crucial, but difficult-to-test, role in changes in surface elevation. Although measuring past surface heights remains a challenge, indications of such processes suggest that surface uplift associated with such removal can affect relative plate motion. Climate change, from a warmer to cooler climate, and associated changes in erosion and sedimentation introduce further complications to determining past elevations. The phenomena that led to such cooling include a number of possibilities, but I favor the emergence of islands in the Maritime continent, which transformed the Pacific Ocean from one with a warm eastern tropical Pacific, as during El Niño events, to the present-day La Niña–like background state. Teleconnections from the eastern tropical Pacific to Canada affect the duration of summers and the potential of high-latitude ice to accumulate. ▪Lateral gradients in gravitational potential energy per unit area (GPE), a force per unit length, govern large-scale continental dynamics.▪Removal of mantle lithosphere and thickening of crust raise GPE; knowledge of mean surface elevations provides a test of these processes.▪Climate change from a warmer to cooler climate and from one with less to more erosion can give the false impression of elevation change.▪Emergence of Indonesian islands, more rain over them, a stronger Walker Circulation, and cooler eastern Pacific may have led to ice ages.

Future climate doubles the risk of hydraulic failure in a wet tropical forest.

Future climate presents conflicting implications for forest biomass. We evaluate how plant hydraulic traits, elevated CO2 levels, warming, and changes in precipitation affect forest primary productivity, evapotranspiration, and the risk of hydraulic failure. We used a dynamic vegetation model with plant hydrodynamics (FATES-HYDRO) to simulate the stand-level responses to future climate changes in a wet tropical forest in Barro Colorado Island, Panama. We calibrated the model by selecting plant trait assemblages that performed well against observations. These assemblages were run with temperature and precipitation changes for two greenhouse gas emission scenarios (2086-2100: SSP2-45, SSP5-85) and two CO2 levels (contemporary, anticipated). The risk of hydraulic failure is projected to increase from a contemporary rate of 5.7% to 10.1-11.3% under future climate scenarios, and, crucially, elevated CO2 provided only slight amelioration. By contrast, elevated CO2 mitigated GPP reductions. We attribute a greater variation in hydraulic failure risk to trait assemblages than to either CO2 or climate. Our results project forests with both faster growth (through productivity increases) and higher mortality rates (through increasing rates of hydraulic failure) in the neo-tropics accompanied by certain trait plant assemblages becoming nonviable.

Observing glacier elevation changes from spaceborne optical and radar sensors – an inter-comparison experiment using ASTER and TanDEM-X data

Abstract. Observations of glacier mass changes are key to understanding the response of glaciers to climate change and related impacts, such as regional runoff, ecosystem changes, and global sea level rise. Spaceborne optical and radar sensors make it possible to quantify glacier elevation changes, and thus multi-annual mass changes, on a regional and global scale. However, estimates from a growing number of studies show a wide range of results with differences often beyond uncertainty bounds. Here, we present the outcome of a community-based inter-comparison experiment using spaceborne optical stereo (ASTER) and synthetic aperture radar interferometry (TanDEM-X) data to estimate elevation changes for defined glaciers and target periods that pose different assessment challenges. Using provided or self-processed digital elevation models (DEMs) for five test sites, 12 research groups provided a total of 97 spaceborne elevation-change datasets using various processing approaches. Validation with airborne data showed that using an ensemble estimate is promising to reduce random errors from different instruments and processing methods but still requires a more comprehensive investigation and correction of systematic errors. We found that scene selection, DEM processing, and co-registration have the biggest impact on the results. Other processing steps, such as treating spatial data voids, differences in survey periods, or radar penetration, can still be important for individual cases. Future research should focus on testing different implementations of individual processing steps (e.g. co-registration) and addressing issues related to temporal corrections, radar penetration, glacier area changes, and density conversion. Finally, there is a clear need for our community to develop best practices, use open, reproducible software, and assess overall uncertainty to enhance inter-comparison and empower physical process insights across glacier elevation-change studies.