Trending Zone Research Articles

Quantitative Assessment of Ecological Sustainability Development in Taiwan Coastal Zone Based on the Coastal Development Index

Quantitative assessment of coastal ecological sustainability development has received increasing interest in regional sustainable development research. It has a strategic value in guiding coastal zone management. We apply the Coastal Development Index (CDI) to quantify the ecological sustainability development in Taiwan coastal zone from 2000 to 2019. The results reveal a relatively high level of ecological sustainability with an overall inverted V-shaped trend in Taiwan coastal zone during this period. The coordination between environmental protection and economic growth in Taiwan coastal zone has experienced an uncoordinated → coordinated → uncoordinated process. Tracking the index of six sub-indicators shows some issues such as over-focusing on quantity rather than quality in coastal protection and facing a "green trap" in economic development. Moderate economic growth is crucial to realize the ecological sustainability development in Taiwan coastal zone. This study demonstrates the value of CDI in the quantitative assessment of ecological sustainable development with a detailed case study in Taiwan coastal zone. It also provides long-term historical data and information on Taiwan region, which may contribute to promoting coordinated development on both sides of the Taiwan Strait.

Effect of the coal-spreading air on airflow and low-NOx combustion within a 75 t/h coal-fired grate furnace

Coal-fired grate furnaces equipped with coal throwers, which conventionally own a low-NOx combustion framework consisting of (i) the partitioned primary air for the horizontal air staging on the grate and (ii) the coal-spreading air and secondary air for the vertical air staging in the freeboard, actually suffer from poor burnout and apparently high NOx emissions at habitual operations. While comprehensive investigations on the in-furnace airflow, coal combustion, and NOx formation, which are devoted to first explaining and then improving these problems, are absent up to now. In order to unveil the airflow, combustion, and NOx emission characteristics within a 75 t/h coal-fired reverse grate furnace, evaluate its coal-spreading air impact on the low-NOx combustion performance, and determine an appropriate coal-spreading air ratio for improving the furnace performance, both industrial-scale tests and numerical simulations were performed at the coal-spreading air ratios of 2 %, 4 %, 6 %, and 8 %, respectively. The flow-field deflection and asymmetric combustion appeared in the upper furnace, with the upward gas deflecting towards the rear-wall side and the front-half furnace part dominated by a weak recirculation zone without effective combustion. With increasing the coal-spreading air, problems of the flow-field deflection and asymmetric combustion aggravated. The combustion intensity weakened in the layer combustion zone while displayed an increase-to-decrease trend in the suspension combustion zone. In terms of indexes related to the furnace performance, burnout rate decreased continuously, and NOx emissions initially raised but then decreased. A comprehensive consideration of the coal-spreading requirement via air, flow-field symmetry, low-NOx combustion, and burnout suggests that a 2 % coal-spreading air ratio should be preferred, where NOx emissions and burnout loss were gained at 249 mg/m3 (6 % O2) and 5.75 %, respectively. It reduced NOx emissions by 49 % while raised slightly burnout loss, as compared with the corresponding levels of 486 mg/m3 and 5.4 % at the habitual case. These results not only negate the air-staging function of the coal-spreading air but also highlight the novelty of this work.

Ecological perspectives on water quality and zooplankton diversity in the Ravi River

AbstractFreshwater ecosystems are intricately linked to the diversity and abundance of zooplankton assemblages, which serve as vital indicators of environmental conditions. The aim of the present study was to investigate the habitat ecology in relation to zooplankton abundance of the Ravi River. Sampling was conducted at selected sampling sites along the Ravi River basin, encompassing various habitat types and environmental gradients. A total of 13 species of zooplankton were observed during the study in which Copepoda was most dominant followed by Cladocera. Cyclops sp. (152 ind/L) and Bosmina sp. (145 ind/L) were the dominant genera throughout the study. Asplanchana sp. (44 ind/L) was observed as a rare species during the study. Some habitat ecological parameters like water temperature, dissolved oxygen, and total dissolved solids show a declining trend in Zone 3. Turbidity was highest in Zone 3 and lowest in Zone 1, and almost all zooplankton genera showed a declining trend in Zone 3. Dissolved oxygen shows a significant positive correlation and directly influences the distribution of zooplankton assemblage structure. This study concludes that certain anthropogenic activities like municipal dumping, sand mining, and altered water flow have negatively impacted water quality and zooplankton diversity in the Ravi River. So, these types of activities should be monitored regularly and controlled immediately.

An integrated model chain for diagnosing and predicting conflicts between production-living-ecological space in lake network regions: A case of the Dongting Lake region, China

The disorderly expansion of human production-living construction activities into aquatic ecological sensitive areas has triggered severe production-living-ecological space (PLES) conflicts. However, research on the risk-triggering mechanisms of PLES conflicts in lake network regions and multidimensional scenario simulation techniques is relatively lacking. To address these issues, this study constructs an integrated model chain by coupling the Markov-GMOP-PLUS model to achieve a quantified diagnosis and simulated regulation of spatial conflict strength index (SCSI) under sustainable development goals. Applying it to the Dongting Lake region reveals that: (1) The overall PLES exhibited a distribution pattern where “ecological space encompasses production space, with living space interspersed within”. The category conversion mainly reflected the encroachment of agricultural production space on the plain water ecological space, with a conversion area of up to 899.48 km2. (2) The distinctive “high in the north, low in the south” PLES conflict pattern was closely aligned with the land use structure and water system distribution, with conflict hotspots persistently clustering in the core lake network regions amid rapid urbanization. Among these, the growth rate of severe conflicts in the last ten years was 3.86 times that of the previous ten years. (3) The sustainable development scenario showcased the most effective conflict mitigation by curtailing production-living space expansion and ecological space encroachment. This scenario reversed the growth trend in conflict high-value zones and the reduction trend in low-value zones, with change rates of −3.30 % and 7.05 %, respectively, compared to 2020. This study provides a scientific basis for formulating sustainable land-use policies in lake network regions.

Aridification and Its Impacts on Terrestrial Hydrology and Ecosystems over a Comprehensive Transition Zone in China

Abstract In China, the topography, climate, ecology, hydrology, and human environment vary greatly from southeast to northwest, and a typical natural and social environmental transition zone (i.e., comprehensive transition zone) exists near the “Hu Huanyong line,” which is a famous demographic dividing line in China, known as the Hu zone. Dry and wet climate changes in the Hu zone can have a significant impact on terrestrial ecosystems and hydrological conditions, ultimately affecting human–land relations. However, there is still a lack of clear understanding of environmental changes in the context of climate change in the Hu zone. Here, a quantitative analysis of climate change and its impacts on terrestrial hydrology and ecosystems from 1951 to 2020 is presented. The results showed that there exists a significant drying trend in the Hu zone and a dramatic decrease in terrestrial water storage (TWS), indicating that the environment has become worse. Conversely, from the perspective of significant greening, the environment has improved. This contradiction is mainly due to climate change dominating the depletion of TWS, while the increase in vegetation greenness is more driven by human activities including agricultural management and ecological restoration, offsetting to some extent the negative impact of water scarcity on vegetation growth. Significance Statement The Hu zone is a transition zone between southeast and northwest China, which is a sensitive area under climate change as well as key region for coordinated development. The purpose of this study is to reveal the long-term climate change in the Hu zone and its impacts on hydrology and ecology. Our results indicate a significant drying trend in this zone over the last 70 years, which led to a substantial reduction in water storage. However, the vegetation coverage increased due to human activities. This study provides guidance for agricultural structure adjustment and ecological protection in transition zones. Future research should focus more on the assessment and risk management of dry/wet changes in climate transition areas around the world.

Structure and Tectonic Evolution of the NW Sulu Sea Basin (SE Asia)

AbstractWe discuss the tectonic structure, seismic stratigraphy and evolution of the NW Sulu Sea using reprocessed 2D reflection profiles. The NW Sulu Sea is located between the Palawan continental shelf and the Cagayan Ridge and represents the northern part of the Sulu Sea, a marginal sea resulting from Paleogene extension and subsequent Neogene contraction due to convergence between the Palawan and the Philippine blocks. The basin consists of six seismo‐stratigraphic units overlying crystalline basement. Syn‐orogenic depocenters contain calibrated Middle Miocene to, possibly, Lower Miocene units, while rift‐related depocenters consist of uncalibrated but tentatively dated Paleogene to Lower Miocene units. Thickness and depth maps of the main units and bounding horizons differentiate the Piedra‐Blanca and the Rasa domains, separated by the NW‐Sulu‐Break major tectonic structure. Fault‐bounded rift‐related depocenters are strongly segmented. We interpret that NW‐SE and NE‐SW trending zones accommodate shape and trend variations of these depocenters. We suggest that these zones may link rift segments, recording different extensional deformation. Miocene thrusting and folding in the Piedra‐Blanca Domain and mudflow with associated gravitational structures in the Rasa Domain influenced the deposition of syn‐orogenic units. Rift structures inherited from rift segmentation may have conditioned the style and distribution of contractional deformation during the subsequent incipient reactivation during contraction. In the context of SE Asia, our results support that the timing of rifting of the NW Sulu Sea overlaps with the opening of the South China Sea and the North Palawan margin, which may indicate a common geodynamic driving force triggering extension.

Two decades of fire activity over the PEEX domain: a look from space, with contribution from models and ground-based measurements

ABSTRACT It has been suggested that forest fires will become more frequent/intense with changing climate, which would increase aerosol/gas emissions into the atmosphere. A better understanding of the relations between meteorological conditions, fires, and fire emissions will help estimate the climate response via forest fires. In this study, we use ERA5 meteorological products, including temperature, precipitation, and soil moisture, to explain the frequency of forest fires and the amount of radiant energy released per time unit by burning vegetation (fire radiative power, FRP). We explore the relationships between satellite-retrieved fire products and aerosol properties (aerosol optical depth, AOD), carbon monoxide (CO), formaldehyde (HCHO), and nitrogen dioxide (NO2) concentrations over the PEEX domain, which covers different vegetation zones (e.g. croplands/grasslands, forest, arctic tundra) of Pan-Eurasia and China. We analyse the concentrations of black carbon and absorbing organic carbon using ground-based AErosol RObotic NETwork. The analysis covers the months of May to August from 2002 to 2022. We show positive temperature trends in the Northern zone (>65°N) in June and August (1.56°C and 0.64°C, respectively); all statistically significant trends for precipitation and soil moisture are negative. This can explain increased fire activity in Siberia over the recent years (2019–2022). Over the whole PEEX domain, FC and FRP trends remain insignificant or negative; a decrease in AOD may address those negative trends. We show that intra-summer variations exist for cropland/grassland fires, which occur most often in May and August, while Siberian forest fires occur more often in July and August. We show that CO concentration has been gradually decreasing in the last two decades in May and June. CO trends are negative in May, June, and over summer for all regions, in July in Europe, China, the Southern zone (<55°N), and the PEEX domain. HCHO trends are not significant in all regions. NO2 trends are positive in May and negative in June in all zones. We calculated total column enhancement ratios for satellite observations influenced by wildfires. A common feature has been recognized with measurements and ratios utilized in SILAM (System for Integrated Modelling of Atmospheric Composition): AOD(or PM):CO and AOD(or PM):HCHO ratios for grass are clearly lower than for shrubs, opposite for AOD:NO2. We showed that emission ratios are increasing towards South and are 2–3 times higher for high (>0.5) AOD. Using a 21-year satellite record of the AOD and CO, an 18-year record of NO2, and a 16-year record of HCHO, we created background products of those variables over the PEEX domain. In the regions with low anthropogenic activity and conditions where long-range transport is not happening, anomalies in AOD, CO, and HCHO over biomass-burning areas may be assigned directly to the wildfire emissions.

A cross-analysis matrix comparing multi-site Local Climate Zone trends: Application to identify sustainable built morphologies improving summer daytime urban microclimate

Sustainable urban planning must address multi-criteria issues, like urban heat island and outdoor thermal comfort. The Local Climate Zone (LCZ) classification links microclimatic measurements with morphological metadata, but multi-site comparisons are hindered by differences in background climates and landscapes. This study resolves this issue developing a methodology to identify common trends across LCZs worldwide. An application during summer daytime allowed to compare LCZ trends of air temperatures and outdoor thermal sensations. Urban vegetation emerges as a powerful means to reduce both. Generalizable LCZ insights provided by this methodology would prove highly valuable to help practitioners to identify efficient urban designs.

Сhanges in the Thermal Condition Trends in the Tropical Zone of the Pacific Ocean in 1982–2021

Сhanges in the Thermal Condition Trends in the Tropical Zone of the Pacific Ocean in 1982–2021

Impacts of changing climate and topography on snow cover variability of Parvati River Basin, western Himalayas, India.

Snow cover is an essential element of the Himalayan region (Third Pole), and it represents the impacts induced by climate change. Recently, studies have reported significant variations in the Himalayan snow cover area, which may impact the livelihood of a large portion of the global population. Therefore, in this study, efforts were made to estimate the association between key climate stressors (CSs), i.e., temperature and precipitation, topography, and temporal variability of snow cover area (SCA) in the Parvati River basin (PRB) of the Indian western Himalayas. In this regard, the PRB has been classified into different elevation zones, i.e., zone I to zone V, ranging from 1100 to 6200 amsl. The databases such as MODIS, MEERA-2, and ASTER DEM V2 have been used to estimate the changes in the SCA and the CSs with changes in elevation and seasons. The linear regression analysis of the dataset from 2001 to 2017 revealed a significant association and increasing trend in the SCA of zone III. However, a significant association could not be established between the elevation and the SCA for the rest of the zones. A zonal seasonal trend investigation of the SCA observed an increasing trend in zones IV and V during the summer season due to a momentous rise in snowfall and a decline in temperature. The SCA has shown a significant declining trend only during the monsoon season in zones IV and V, which is due to a strong negative relationship between the SCA and the temperature of the region. These results demonstrate the amount of SCA in zones of high elevation of the PRB has been declining at an alarming rate, which could negatively influence glaciers' retreat in the near future. Hence, it can be estimated that the outcomes of the study will act as a base for future studies, regional policy formulation, and climate modelling that can further prevent future drastic or extreme events.

Continuous vs. discontinuous garnet growth in mylonitic micaschists from northeastern Sardinia, Italy: Evidence from LA-ICPMS trace element mapping

Garnet with complex, discontinuous zoning is a common occurrence in metamorphic terrains, and the relationship between major and trace element zoning can provide insight into the metamorphic evolution of the host rock. Mylonitic micaschists along the Posada-Asinara Shear Zone in the Axial Zone of the Sardinia Variscan chain contain garnet porphyroblasts, enveloped by the S2 schistosity, with distinct core and rim domains. A large garnet porphyroblasts was investigated by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS) mapping. The major element compositional variation follows a bell-shaped zoning, with Ca and Mn contents progressively decreasing, and Fe and Mg increasing, from the core to the outer rim. LA-ICPMS mapping revealed a thin and sharp annular enrichment zone in Y, Sc, Dy, Ho, Er, Tm at the mantle-rim boundary. The trace element (TE) compositional profiles show a central enrichment area for HREE (Tm, Yb, Lu). This enrichment decreases progressively, as a function of atomic number, for Er, Ho and Dy. Elements with even lower atomic number (Tb, Gd, Eu and Sm), are depleted in this central domain, but their content increases in broad shoulders towards the garnet rim. The position of these lateral shoulders migrates progressively rimwards with decreasing atomic number. The REE distribution, trend and behavior in the growth zones of the garnet is an example of TE control during a continuous growth ruled by diffusion-limited REE uptake. The Y + HREE annular enrichment zone, interpreted as resulting from a decrease in the garnet growth rate, reflects a short-lived episode in the garnet growth history.

Comprehensive assessment of four volcano-hosted geothermal fields with relation to tectonics and faults in El Salvador

Geothermal systems have noteworthy prospects for replacing the reliance on fossil fuels. El Salvador, located in a tectonically active region, supplies 25 percent of the annual electricity demand from two hosted volcanic geothermal fields. This contribution may be increased by up to 40 percent by developing two additional explored geothermal areas. Although El Salvador has a high potential for geothermal energy, studies have yet to be conducted to explore the characteristics and differences of the current geothermal fields. This study summarizes current information on the leading explored geothermal areas in El Salvador. We compared the features of the four most studied geothermal areas using regional and local tectonics, representative drilled-well lithology, hydrothermal alterations, and the resistivity structure along the magnetotelluric profile. Our results show that regional tectonics and local fault systems mainly control the characteristics of the geothermal reservoirs in El Salvador. The likelihood of identifying fractured geothermal reservoirs increases significantly in areas where the local fault system differs from the El Salvador Fault Zone (ESFZ) trend. Fractured areas adjacent to volcanic structures with substantial meteoric water recharge are highly effective geothermal energy sources. Our study enhances the understanding and exploration of the geothermal resources of El Salvador.

Сhanges of Thermal Conditions Trends in the Tropical Zone of the Pacific Ocean in 1982–2021

Based on National Oceanic and Atmospheric Administration (NOAA, USA) and Japan Meteorological Agency (JMA) climate data sets for 1982–2021, regional features and trends of interannual changes of water temperature in the upper 2200-m layer of the Pacific Ocean tropical part were investigated, as well as their possible relationships with variations of climatic characteristics. Obtained results provide description of three-dimensional structure of the temperature anomalies and heat content variability in the water column and rate of warming in the various areas for specific phases of the resent global warming.

Chickens feed resources and feeding trends in Konso Zone and Derashe special district, Southern Ethiopia

The study was conducted to assess locally available chicken feed resources and feeding trends in the Karat zuria district of the Konso zone and Derashe special district. Multi-stage sampling techniques were used and a total of 120 respondent farmers from the districts who possess chicken production were involved. The data were collected by questionnaire, personal observation, and interviews. Potential cereals: sorghum (95.0±0.22% and 86.7±0.34%), teff (65±0.48% and 66.7±0.48%) from pulses haricot bean (58.3±0.50% and 45.0±0.50%); as vegetables Moringa stenopetala locally: Halako (96.7±0.18 and 91.7±0.28) in Karat zuria and Derashe special districts, respectively were identified as commonly locally promising human food as well as chicken feeds. Cooked food scraps (Fosase, Kurkufa); kitchen wastes, and protein sources (growing worms, termites, insects, grasshoppers, flies) local brewery residues (Cheka residues) were highly ranked as potential scavengeable feed resources (SFR) in both districts. However, January to May is the major month of the year severity of feed shortage (90% of respondents) mostly occurred. About 2/3 of farmers spreading the grain on the bare ground together for the whole groups of chicken once per day mainly for egg yield (41.67% of respondents) in the area was a very common trend of providing supplementary feed. Consequently, efforts have to be made to design and implement interventions, aiming at improving chicken feed resource base and feeding trends.

Analysis of the Composite Risk Grade for Multi Extreme Climate Events in China in Recent 60 Years

Much attention has been given to the change rule of a single extreme event, and there are few reports on comprehensive characteristics of multiple extreme events in a certain region. Based on the analyzes of annual frequency of extreme high temperature, extreme low temperature, extreme drought, extreme precipitation, and extreme typhoon events in China from 1961 to 2020, a multi extreme events composite risk grade index (MXCI) was constructed and applied to the comprehensive characteristics analyzes of multiple extreme events in China. The results show that the high value areas of MXCI were mainly located in southeast China and southwest China. Over the past 60 years, the MXCI has shown a decreasing trend in western China and most of southeastern China, and an increasing trend in the middle zone from southwest China to northeast China. Through comparative analysis, MXCI can objectively reflect the comprehensive characteristics of multiple extreme climate events in a region, which is helpful to understand regional extreme climate characteristics and effectively cope with extreme climate risks.

Spatial distribution of drinking and irrigation water quality in different climatic zones of Baluchistan, Pakistan.

Baluchistan's water profile was developed by dividing it into seven zones (Northern Highlands-NH, Southern Highlands-SH, Quetta Valley-QV, Desert-D, Sibbi Plains-SP, Coastal Lasbella-CL, Coastal Gwadar-CG) based on geography, water availability, and climate of the area. A total of 106 water samples were collected from karaiz, spring water, and tube wells. Spatial distribution of EC, TDS, TH, SO42-, Cl-, Na+, and K+ showed an increasing trend in concentration from the highlands towards the desert and coastal zones. For anion, HCO3- is predominant in NH, SH, and QV, Cl- in D, CL, and CG and only SO42- in SP, whereas the cationic trend in overall zones is Na+>Ca2+>Mg2+>K+. In the NH, SH, QV, and SP zones, the physicochemical parameters met the drinking water quality guidelines; however, D, CL, and CG exceeded in almost all quality parameters. Furthermore, the drinking water quality index (WQI) shows excellent to good water quality in NH, SH, QV, and D zones, while CL and CG fall in poor to unsuitable water classes. In terms of hydrogeochemical facies, maximum water samples from NH fall in Ca-Mg-HCO3, and SH, QV, and SP in Ca-Mg-Cl type, where major ion chemistry is controlled by rock-weathering, while D, CL, and CG fall in the NaCl type, where evaporation is dominant. Similarly, irrigation water quality parameters (EC, SAR, RSC, Na%, MH%, PI, SSP, and KR) reveal that NH, SH, QV, and SP have suitable water for irrigation, and D, CL, and CG require proper treatment. Additionally, USSL and Wilcox's diagrams indicated that NH, SH, QV, and SP have "excellent to permissible"; however, D, CL, and CG have "permissible to unsuitable" class water, requiring special management practices. Consequently, appropriate control measures and targetedwater purification programmes should be implemented to protect the publichealth and sustainability of water resources inBaluchistan.

Seismicity at the intersection of the Coast Shear Zone and Anahim Volcanic Belt near Bella Coola, British Columbia, Canada

In the Coast Mountains of western British Columbia, an anomalous seismicity concentration exists near the intersection of the Coast Shear Zone, a major northwest–southeast trending Eocene-age shear zone that accommodated deformation between the Pacific and North America plates, with the Anahim Volcanic Belt, an east-northeast–west-northwest trending zone of volcanic features that decrease in age to the east. To better characterize seismicity in the Coast Mountains, we augment the existing Natural Resources Canada seismicity catalogue by applying an automatic detection and location algorithm to both permanent Canadian National Seismic Network stations and temporary stations from the 2005–2006 BATHOLITHS deployment, resulting in 837 relocated events with at least three paired P- and S-phase picks. Double-difference relocation reveals several small-scale linear strands subparallel to the Coast Shear Zone and within the Anahim Volcanic Belt and three clusters of events striking at a high angle to the Coast Shear Zone that occurred as swarms in 2015 and 2017. First-motion focal mechanisms exhibit extensional and strike-slip faulting. Our observations indicate that most of these events are not associated with surficial processes such as landslides, but rather, we hypothesize that the interaction of the Anahim Volcanic Belt and Coast Shear Zone has weakened the lithosphere in this region, leading to current-day strain localization and high heat flow that manifest seismicity, including swarm-like activity.

Changes in vegetation greenness related to climatic and non-climatic factors in the Sudano-Sahelian region

The potential drivers of vegetation changes in the Sudano-Sahelian region of Africa remain poorly understood due to complex interactions between climatic and anthropogenic processes. In this study, we analyzed the vegetation greenness trends in relation to rainfall variability that we considered the essence of climatic effects on vegetation in a well-known water-limited environment by using time series of satellite data in the Sudano-Sahelian region during 2001–2020. We quantified in more detail the relative contributions of rainfall variability (climatic factor), land use/land cover (LULC) change, and fire occurrence change (non-climatic factors) to vegetation greenness trends in selected sub-regions. The results showed that vegetation greening was widespread (26.9% of the total study area), while vegetation browning was more clustered in central West Africa (5% of the total study area). About half of the vegetation greening area can be explained by long-term rainfall variability during 2001–2020, but most of the area characterized by a browning trend was unrelated to rainfall variability. An analysis of the relative importance showed that LULC changes had significant local effects on vegetation greenness and that these changes were characterized by a strong spatial heterogeneity in specific sub-regions. Gains in cropland and natural vegetation related to positive land management were probably the dominant drivers of greening in Senegal and Ethiopia. Also, the combined impacts of rainfall variability and LULC changes contributed to greening trends in the arid zone, particularly in Mali and Sudan. In contrast, vegetation browning in central West Africa appeared to be driven by cropland gain and natural vegetation loss associated with extensive agricultural production activities. Furthermore, we found that repeated fires for agricultural expansion in central West Africa intensified vegetation browning. These results advanced our understanding of vegetation dynamics in response to climatic and non-climatic factors in Sudano-Sahelian drylands characterized by increasing pressures on land resources.

DUACS DT2021 reprocessed altimetry improves sea level retrieval in the coastal band of the European seas

Abstract. More than 29 years of altimeter data have been recently reprocessed by the multi-satellite Data Unification and Altimeter Combination System (DUACS) and made available under the name of DT2021 through the Copernicus Marine Service (CMEMS) and the Copernicus Climate Change Service (C3S). New standards have been applied and various geophysical correction parameters have been updated compared to the previous release in order to improve the product quality. This paper describes the assessment of this new release through the comparison of both the all satellites and the two satellites product with external in situ tide gauge measurements in the coastal areas of the European seas for a time period from 1 January 1993 to 31 May 2020. The aim is to quantify the improvements on the previous DT2018 processing version for the retrieval of sea level in the coastal zone. The results confirmed that the CMEMS product in the new DT2021 processing version better solves the signal in the coastal band. The all satellites dataset showed a reduction of 3 % in errors when compared with tide gauges and of 5 % in the variance of the differences between the datasets compared to DT2018 reprocessing. Moreover, the all satellites dataset provided more accurate sea level measurements when making a comparison with tide gauges with respect to the climatic two satellites dataset due to the better performance of the former for the assessment of higher than climatic frequency signals. By contrast, the two satellite dataset is the most suitable product for the assessment of long-term sea level sea surface height (SSH) trends in the coastal zone due to its larger stability to the detriment of the all satellites dataset.

Geochemical precursory characteristics of soil gas Rn, Hg, H2, and CO2 related to the 2019 Xiahe Ms5.7 earthquake across the northern margin of West Qinling fault zone, Central China

The Xiahe Ms5.7 earthquake occurred in Xiahe county, Gannan prefecture, China (35.10°N, 102.69°E) on October 28, 2019, with a source depth of 10 km. This study investigates the spatial and temporal evolution characteristics of cross-fault soil gas concentrations prior to the Xiahe Ms5.7 earthquake by analyzing Rn, Hg, H2, and CO2 data collected from 11 profiles across the northern margin of the West Qinling fault zone from 2016 to 2019. The spatial distribution of these gases showed varying trends, with Rn concentration intensity decreasing from the Wushan segment to the east and west sections, while Hg, H2, and CO2 all broke the trend in the West Qinling fault zone's northern margin. The soil gas concentration intensity demonstrated a significant response to the Xiahe Ms5.7 earthquake, particularly in the west Ganjia sections. By integrating the seismogenic model and numerical simulation results, we explored the physical mechanism underlying these abnormal trends. Our findings suggest that the continuous decline characteristic of fault gas could be a valuable indicator of fracture tectonic activity, while an upward trend after continuous decline may signal a medium and short-term seismogenic event in the source area. These results provide a foundation for improved tracking of earthquake location and timing in a fault zone through cross-fault soil gas methods, highlighting the importance of enhancing deep fluid flow monitoring and seismogenic model research in fault zones.