bluuebunny/crossref_metadata_2025 huggingface dataset:
Main controlling factors of volcanic oil and gas distribution and charging capacity evaluation of Huoshiling Formation in Longfengshan area
Authors: Hou Shuai , Jiang Youlu
Published: March 2024

There are two sets of petroliferous strata developed in the Huoshiling Formation volcano in the Longfengshan area of the Changling fault Depression. The oil and gas have the characteristics of "near source gas, far source oil rich", the abundance of oil and gas decreases from the depression zone to the western tectonic belt, and is enriched in the top and middle of volcanic rocks in longitudinal direction, and widely distributed along faults in plane. In this paper, the controlling factors of hydrocarbon distribution in volcanic rocks are discussed from the perspectives of source rock development condition, reservoir physical property and transport condition by means of seismic, well logging and geochemical data, cores and microsections observation, CT scanning and inclusion analysis. The results show that the oil and gas distribution in the volcanic rock mass in Longfengshan area is mainly affected by the following factors: the thermal evolution degree of the source rock controls the oil and gas phase distribution, and the source and reservoir configuration determines the oil and gas capture probability; The distribution characteristics of high-quality volcanic rock reservoir can control the distribution range of oil and gas, and the vertical development difference of primary, secondary dissolution and fracture high-quality reservoirs determines the vertical accumulation of oil and gas. The fault and unconformity control the migration of oil and gas from the depression zone to the slope zone and the western tectonic zone, and its transport performance and the micro-transport structure of internal fractures ultimately determine the location of oil and gas accumulation. The distribution of overlying layers in and above volcanic rocks, the type of reservoir-cap combination and the configuration of broken cap prevent the oil and gas loss and control the oil and gas enrichment horizon. Based on the differences of main controlling factors of hydrocarbon accumulation in volcanic rocks, the effective source rock thickness, volcanic reservoir physical properties, reservoir-cap combination characteristics and transport conditions are taken as indicators to evaluate the hydrocarbon charging capacity of volcanic rocks, and the measured values of the above factors are divided into several intervals. According to the distribution range of the evaluation index, each interval is evaluated. Finally, according to the calculation results of the established oil and gas charging capacity evaluation formula, the evaluation results have a good correspondence with the current oil and gas distribution, and the results have certain guiding significance for determining the direction of oil and gas exploration in the later period.
Dynamic drainage reorganization in the eastern Tibetan Plateau: A perspective from the First Bend of the Yangtze River
Authors: Zhao Xudong , Zhang Huiping , Li Yifei , Lease Richard
Published: March 2024

The establishment of modern drainage patterns of large rivers in eastern Tibet is thought to have resulted from drainage reorganization by serial river capture and reversal events, but the timing and driving mechanisms are still under debate. The capture that created the First Bend of the Yangtze River (YFB) is the most well-known event but also the most controversial. Here, sedimentary provenance of Late Miocene–Quaternary Dali basin strata south of the YFB demonstrates that a south-flowing Jinsha River briefly drained the Dali basin at ~7.4–6.4 Ma. This would require the occurrence of two fluvial diversions at the YFB, before 7.4 Ma and after 6.4 Ma, respectively. Together with landscape evolution modeling results, we infer that a river-blocking landslide downstream of the YFB and resulting lake overspill may have been responsible for this drainage reorganization process. Our results highlight for the first time that river-damming landslides may be a key mechanism for driving dynamic drainage reorganization in eastern Tibet.
How accurately does L band vegetation optical depth predict aboveground biomass?
Authors: Zhang Yuan , Ciais Philippe , Wigneron Jean-Pierre , Chave Jérôme , Cong Nan , Li Xiaojun , Yang Yan , Saatchi Sassan
Published: March 2024

L band vegetation optical depth (L-VOD) is a widely used remote sensing variable for investigating the spatiotemporal variation in aboveground biomass (AGB). A key step of this method is to fit L-VOD against AGB, then use a space-for-time assumption to infer AGB change from fitted L-LOD change. In this study, we evaluated the performance of different fitting equations and explored their implications in predicting AGB. We used the SMOS-ICV2 L-VOD dataset and four AGB reference datasets. Specifically, we examined the implications of the space-for-time assumption in predicting the AGB interannual variations. We find that all the statistical fitting methods can capture the AGB spatial variation, yet introducing tree cover as a predictor significantly improves the AGB prediction, especially in regions with small and medium L-VOD values. However, these methods all fail to capture AGB spatial variation in dense forests. The AGB reference data also show large discrepancies in these regions. Our results also show that the spatial AGB sensitivities to L-VOD are much larger than the temporal AGB sensitivities to L-VOD, implying considerable uncertainties in temporal AGB changes predicted with spatially built models. By providing a comprehensive evaluation of fitting methods, our results offer a cautionary tale to the use of L-VOD data to infer AGB dynamics and the necessity of developing long-term field-based biomass change datasets for further constraining and evaluating AGB predictions from remote sensing observations.
Investigate the Effects of Compound Extreme Climate Events on Global  crop Yield from 1982 to 2
Authors: kun xiao , Xin Qin chuan xin
Published: March 2024

In the context of global climate change, extreme climate events are becoming increasingly frequent.  Extreme climate events constitute major risks to global food security. The simultaneous occurrence of multiple extreme climate events may have a much greater impact than individual extreme events in isolation. Here we quantitatively analyzed the impact of individual and combined extreme climate indices, including cold days (CD), warm degree days (WDD), precipitation, and compound hot – windy - dry (HWD), on the yields of three major crops (winter wheat, soybeans, and maize) globally by establishing a linear mixed-effects model. CD, HWD, and WDD are identified as the most significant driving factors causing yield losses in winter wheat, soybeans, and maize, respectively. During the planting to the jointing stage, per 10 days of CD account for a 3.2% reduction in winter wheat yield. During the jointing to heading stage, per 10 h of HWD and per 10 °C day-1 WDD result in a 7.5% reduction in soybean yield and a 2.7% reduction in maize yield, respectively. We quantified "yield shocks" and found that the regions experiencing yield shocks exhibit a similar spatial distribution to extreme climate indices. These extreme climate indices are likely to be the driving factors behind yield shocks for the three crops. Our findings indicate that multiple individual extreme climate factors, as well as compound heat-drought-wind (HDW) indices that have been overlooked in traditional risk assessments, impact the yield of the three major crops globally.
Global Civil Earth Observation Satellite Semantic Database
Authors: Lin Ming , Jin Meng , Li Juanzi , Bai Yuqi
Published: March 2024

The advancement of satellite remote sensing technology has transformed our capacity to monitor and address global challenges. This technology provides global coverage, frequent observation revisits, and consistent monitoring, thus providing critical data support. Since the first Earth observation satellite was launched in the 1960s, more than a thousand Earth observation satellites have been deployed by various countries and organizations. However, the substantial accumulation of Earth observation assets is maintained independently by different organizations using varying methodologies. This poses a significant challenge in effectively utilizing and maximizing the value of these global observation resources.This study introduces GEOSatDB, a comprehensive semantic database specifically tailored for civil Earth observation satellites. The foundation of the database is an ontology model conforming to standards set by the International Organization for Standardization (ISO) and the World Wide Web Consortium (W3C). This conformity enables data integration and promotes the reuse of accumulated knowledge. Our approach advocates a novel method for integrating Earth observation satellite information from diverse sources. It notably incorporates a structured prompt strategy utilizing a large language model to derive detailed sensor information from vast volumes of unstructured text.To demonstrate the capabilities of GEOSatDB, we performed a comprehensive analysis of the distribution of Earth observation satellites in 195 countries. This analysis unveiled the global distribution and diversity of these assets. Furthermore, two distinct case studies showcase the practical application and robust data mining potential of GEOSatDB. With information on 2,340 remote sensing satellites and 1,018 sensors, this database represents a significant advancement in semantically sharing and applying Earth observation resources. Its establishment encourages enhanced international cooperation and more efficient environmental monitoring and management.
Future tropospheric ozone budget and distribution over East Asia under a net-zero scenario 
Authors: Hou Xuewei , Wild Oliver , Zhu Bin , Lee James
Published: March 2024

Under future net-zero emission policies, reductions in emissions of ozone (O3) precursors are expected to alter the temporal and spatial distributions of tropospheric O3. In this study, we quantify changes in the tropospheric O3 budget and in the spatiotemporal distribution of surface O3 in east Asia and the contributions of regional emissions, intercontinental transport and climate change between the present day and 2060 under a net-zero scenario using the NCAR Community Earth System Model (CESM) with online tagging of O3 and its precursors. The results reveal that the global tropospheric O3 burden is likely to decrease by more than 20 %, from 316 Tg in the present day to 247 Tg in 2060, under a net-zero scenario. The burden of stratospheric O3 in the troposphere is expected to increase from 69 to 77 Tg. The mean lifetime of tropospheric O3 is expected to increase by 2 d (∼ 10 %). Changes in climate under a net-zero pathway are relatively small and only lead to small increases in tropospheric O3. Over eastern China, surface O3 increases in winter due to the weakened titration of O3 by NO associated with reduced anthropogenic NO emissions and due to enhanced stratospheric input. In summer, surface O3 decreases by more than 30 ppbv, and peak concentrations shift from July to May. Local contributions from anthropogenic emissions to surface O3 over east Asia are highest in summer but drop substantially, from 30 % to 14 %, under a net-zero scenario. The contribution of biogenic NO sources is enhanced and forms the dominant contributor to future surface O3, especially in summer (∼ 40 %). This enhanced contribution is mainly due to the increased O3 production efficiency under lower anthropogenic precursor emissions. Over eastern China, local anthropogenic contributions decrease from 50 % to 30 %. The decreases in surface O3 are strongly beneficial and are more than sufficient to counteract the increases in surface O3 observed in China over recent years. This study thus highlights the important co-benefits of net-zero policies that target climate change in addressing surface O3 pollution over east Asia.
Separate the impact of climate change and non-climatic factors on hydrological drought based on AdaBoost algorithm
Authors: Wang Wenyucheng , She Dunxian , Xia Jun
Published: March 2024

Hydrological drought occurs frequently all over the world and has a great impact on human beings. Hydrological drought attribution contributes to a better understanding of the mechanisms of drought occurrence, improves the accuracy of predictions of drought events, and can provide a basis for drought risk reduction. At present, hydrological models which possess physical mechanisms are widely used in attribution analysis. However, this kind of models is complex in calculation, and has very limited time scale. In this study, we developed a hydrological drought attribution method via AdaBoost algorithm. The method divided the study period into natural period unaffected by non-climatic factors and impacted period. Taken the natural period as training period, the impacted period as test, the runoff was obtained to calculate the three-months standardized runoff index (SRI-3). Based on the run-length theory, we calculated average drought characteristics in the impacted period. Finally, the proportion of the average drought characteristics obtained by simulated SRI-3 series to those obtained by observed SRI-3 series is considered as the contribution of the climatic factors to the drought events.We applied this method in the Yangtze River Basin and the results showed that climatic factors are the dominate factors affecting hydrological droughts in this region, with the contributions at all the gauge stations are over 50%. Among all the drought characteristics, average drought severity is the most affected by the climatic factors, the corresponding contributions are all greater than 100%, shown as “excess contributions” (with non-climatic factors shown as negative contributions). Through the applications in various sub-basins of the Yangtze River Basin, the method was shown to provide new ideas for hydrological drought attribution, and the method can also be extended for applications such as meteorological hazards attribution, stock market volatility attribution and so on.
Why does the Signal-to-Noise Paradox Exist in Seasonal Climate Predictability?
Authors: Shivamurthy Yashas , Saha Subodh Kumar , Pokhrel Samir , Konwar Mahen , Chaudhari Hemant Kumar
Published: March 2024

Skillful prediction of seasonal monsoons has been a challenging problem since the 1800s. However, significant progress has been made in Indian summer monsoon rainfall prediction in recent times, with skill scores reaching 0.6 and beyond, surpassing the estimated predictability limits. This phenomenon leads to what is known as the “Signal-to-noise Paradox.” To investigate this paradox, we utilized 52 ensemble member hindcast runs spanning 30 years.Through the application of ANOVA and Mutual Information methods, we estimate the predictability limit globally. Notably, for the boreal summer rainfall season, the Indian subcontinent exhibited the paradox, among several other regions, while the Equatorial Pacific region, despite demonstrating high prediction skill, does not have the Signal-to-Noise paradox. We employed a novel approach to understand how sub-seasonal variability and their projection in association with predictors are linked to the paradoxical behavior of seasonal prediction skill.We propose a new method to estimate predictability limits that is free from paradoxical phenomena and shows much higher seasonal predictability. This novel method provides valuable insights into the complex dynamics of monsoon prediction, thereby creating opportunities for expanded research and potential improvements in seasonal forecasting skill in the coming years.
Last Interglacial sea level derived from U-series dated fossil corals of the Turks and Caicos Islands
Authors: Dumitru Oana , Dyer Blake , Austermann Jacqueline , D'Andrea William , Creel Roger , Bolge Louise , Goldstein Steven , Raymo Maureen
Published: March 2024

The timing, magnitude, and evolution of sea-level change during the Last Interglacial period (Marine Isotope Stage (MIS) 5e) are subjects of ongoing debate. Previous estimates of global mean sea level (GMSL) generally converged on values of 5 to 10 meters above present levels, with one or more oscillations of up to several meters. However, more recent studies suggest considerably lower GMSL that peaked below 5 meters. Ancient coral reefs play a pivotal role in providing reliable constraints on MIS 5e sea level because they are often well preserved in the fossil record and can yield precise ages through U-series dating.
Here we present a new series of high-precision U-series ages combined with detailed stratigraphic analysis and accurateelevation measurements of emergent in-situ fossil corals from Turks and Caicos Islands. We sampled well-preserved MIS 5e corals outcropping along the coastlines of North Caicos, Middle Caicos, West Caicos, and Providenciales islands. We identified corals from several paleo-habitats, including platform edge reefs and both isolated corals and patch reefs from the paleo-lagoon. The dominant coral species include Orbicella annularis, Pseudodiploria, Acropora palmata, Acropora cervicornis, and Porites porites. Many fossil corals show evidence of post-depositional alteration of their primary geochemistry. Their utility is therefore limited by their preservation. To identify unaltered corals and maximize the likelihood of closed to near-closed system behavior of our samples, we apply rigorous threshold criteria that screen samples by their mineralogy, U concentration, δ234Uinitial, and amount of detrital component. We further correct the ages for diagenetic disturbance of the U-Th isotope ratios. These results allow us to provide new sea-level constraints during MIS-5e and to assess the amount of ice melt during this period of pronounced warming.
 
Biotic response of deep-sea benthic foraminifera in the northeast tropical Indian Ocean at the onset of the mid-Brunhes dissolution interval
Authors: Takata Hiroyuki , Ikehara Minoru , Seto Koji , Asahi Hirofumi , Lim Hyoun Soo , Hyun Sangmin , Khim Boo-Keun
Published: March 2024

The mid-Brunhes dissolution interval (~533–191 ka) is characterized by various paleoclimatic/paleoceanographic events in the world that occurred mainly at ~400 ka during Marine Isotope Stage (MIS) 11. The duration of MIS 15–12 is important to understand a succession of various paleoclimatic/paleoceanographic events at the onset of the mid-Brunhes dissolution interval (e.g., Birth et al., 2018). For example, MIS 13 was marked by asymmetrical temperature and precipitation between the hemispheres, northward displacement of InterTropical Convergence Zone (ITCZ), and global carbon cycle changes (Ao et al., 2020). We investigated fossil deep-sea benthic foraminifera and sediment geochemistry (11 major elements by XRF analysis) during ~670–440 ka (MIS 16–12) at ODP Site 758 and core GPC03 (2925 m and 3650 m water depth, respectively) in the northeast tropical Indian Ocean (~5°N, ~90°E).Two multidimensional scaling (MDS) axes were recognized in the benthic foraminiferal faunas. MDS axis 1 is related to the specific depth habitats of benthic foraminiferal faunas possibly with trophic level, whereas MDS axis 2 may be related to the low food supply with episodic food pulses/relatively stable low food flux. The difference of MDS axis 1 between ODP Site 758 and core GPC03 was smaller during ~610–560 ka (MIS 15), whereas it was larger during ~560–480 ka (MIS 14–13). MDS axis 2 showed generally similar stratigraphic variations between the two cores during ~610–560 ka, whereas it was different during ~560–480 ka. The proportion of lithogenic matter to biogenic carbonate was also relatively low during ~610–530 ka under the highstand. Thus, both the lithogenic supply and the depth gradient of benthic foraminiferal faunas between the two cores were changed across MIS 15/14 (~570–540 ka).At ODP Site 758, the decrease of Globigerina bulloides across MIS 15/14 implies the long-term weakening of wind-driven mixing of the surface water (Chen and Farrell, 1992). It may be caused by the weakening of the Indian summer monsoon at that time, possibly with the northward displacement of the ITCZ (e.g., Ao et al., 2020). In our study area, the depth gradient of the benthic foraminiferal faunas may be controlled by the linkage between the surface and deep oceans that was altered transiently but significantly across MIS 15/14, possibly through the particulate organic matter ballasting by calcareous plankton skeletons and/or lithogenic matter.
Generation of Neoproterozoic high-silica granites by crystal-melt segregation in the northern Yangtze Block, South China: Implications for the evolution of Precambrian continental crust
Authors: Xue Wenbin , Lai Shaocong
Published: March 2024

There is a consensus that the generation of high-silica granites could undergo obvious crystal-melt separation, which is of significance for comprehending the evolution of shallow magmatic system and silicic upper crust. Although voluminous studies have paid more attention to the crystal-melt segregation mechanism acting on the Phanerozoic high-silica granites and/or rhyolites, it remains unclear whether the evolution and emplacement of Precambrian (especially the Neoproterozoic) high-silica igneous rocks are controlled by this mechanism. Herein we therefore presented comprehensive studies on the petrology, mineralogy, whole-rock geochemistry, and zircon U-Pb-Hf isotopes for the Neoproterozoic high-silica granites (biotite granites and K-feldspar granites) from the Huangling batholith in the northern Yangtze Block (South China), in order to trace their magmatic source and evolutional process. Zircon U-Pb ages reveal that the Huangling biotite granites and K-feldspar granites were formed at ca. 812–818 Ma, belonging to the contemporary Neoproterozoic magmatism. They are characterized by variable and high SiO2 (70.2–74.8 wt.%), K2O (1.3–6.4 wt. %), Rb (28–228 ppm), and Th (1.7–35.1 ppm) contents. The obviously enriched whole-rock Sr-Nd isotopes (εNd(t) = -23.4 to -18.4) and zircon Hf isotopes (εHf(t) = -44.3 to -18.4) with old two stage model ages (TNdDM2 = 2641–2987 Ma, THfDM2 = 2852–4442 Ma) indicate that they sourced from the partial melting of ancient Archean continental crust. The Huangling biotite granites display higher Ba (532–1659 ppm), Sr (450–741 ppm) and Eu/Eu* (0.84–1.40) values, but lower Rb (28–58 ppm) and Th (1.8–5.5 ppm) contents than the K-feldspar granites (Ba = 345–904 ppm, Sr = 108–152 ppm, Rb = 170–228 ppm, Th = 9.8–35.1 ppm, and Eu/Eu* = 0.31–0.46), suggesting that the biotite granites and the K-feldspar granites represent the residual cumulations and extracted high-silica melts from the crystal mush, respectively. Massive mineral aggregates of plagioclases and biotite support the residual crystal accumulations of the Huangling biotite granites, and the higher zircon Hf, Nb concentrations and lower zircon Eu/Eu* ratios of the K-feldspar granites further advocate that they were derived from the more evolved melts. This work emphasized that intensive crystal-melt segregation process in the crystal mush reservoir plays a crucial role of the generation of Neoproterozoic high-silica granites, which are therefore significant for the evolutional process of the Precambrian high-silica continental crust in the northern Yangtze Block.
Modelling convective cell lifecycle with a copula-based approach
Authors: Tseng Chien-Yu , Wang Li-Pen
Published: March 2024

The utilisation of spatial-temporal rainfall generators for urban drainage design or operational planning has largely increased for better reflecting the hydrological response of the catchment. However, a significant challenge that persists within these models is their inadequate representation convective storms. More specifically, the overall variation in spatial and temporal rainfall modelling comprises those resulting from advection and evolution. Most of the generators however neglect the modelling of cell evolution. This deficiency poses difficulties to precise convective storm simulations, consequently leading to potential underestimations of flood risk.In addressing the challenge of modelling convective storms, this study proposes a statistical-based algorithm that enables the generation of convective cell lifecycles accounting for the evolution of cell properties. To develop the algorithm, we first chose an area of approximately 431 km2, centred at Birmingham city, as our study area. A total of 176 effective convective storm events, spanning from 2005-2017, were then identified using ground rain gauge records within the study area. We then utilised the enhanced TITAN storm tracking algorithm, proposed by Munoz et al (2018), to extract convective cell lifecycles for the selected events. Finally, a total of 116,287 lifecycles, comprising 354,855 individual cells, were retrieved, with an average of 660 per storm event.We then investigated these cell lifecycles in three stages. The initial stage was to statistically characterise individual properties of convective cells, including rainfall intensity, spatial extent, and movement velocity. Following this, an investigation of the inter-correlations among these cell properties was conducted. Similar to the findings outlined in the literature, strong correlations could be found between cells’ intensity and their lifespans and between cells’ intensity and their spatial extents. The final stage focused on examining the evolution of these cell properties during their lifetimes. An interesting finding here is that the growth and decay rates of these cell properties are in fact correlated with cell properties themselves. This observation points to the need to incorporate this correlation structure into the process of sampling convective cells.To resolve the complex correlation structure within convective cell evolution, we employed the Copula method, which is innovatively applied to statistically model the complex multi-variate interrelations among the characteristics of convective cells. The vine-copula approach, in particular, can well-reproduce the interrelations present in the dataset. The development of a novel copula-based algorithm for modeling convective cell lifecycles marks a key advancement, offering the potential for enhanced precision in spatial-temporal rainfall generators (McRobie et al., 2013), in depicting regional convective rainfall patterns.
Whole-soil warming effects on carbon cycling of an alpine grassland ecosystem on the Tibetan Plateau
Authors: Zhu Biao
Published: March 2024

The impact of warming on the carbon cycling of terrestrial ecosystems determines the carbon cycle-climate change feedback and the future climate. Specifically, how warming affects the carbon cycling in deep soils (>20 cm) remains uncertain, because most of existing manipulation experiments only warm surface soils (10 years. I will present an overview and some of the results of TEAM during the first 5 years (2018-2023), including treatment effects on plant communities, soil and microbial properties, and ecosystem processes.First, warming did not significantly affect plant richness and diversity, and above- and belowground biomass and productivity, but changed the relative proportion of plant functional groups in aboveground biomass (decrease in legumes and increase in forbs). Second, soil physico-chemical properties (including organic carbon and total nitrogen concentrations) and microbial community characteristics (such as carbon use efficiency, community diversity and composition) throughout the profile were mostly unresponsive to warming, although they changed dramatically (e.g. declined) with depth. Third, warming significantly stimulated soil respiration (and microbial respiration) and soil N2O emission, but did not significantly change root respiration and soil CH4 uptake. Lastly, warming promoted plant growth, soil microbial respiration, and soil fauna feeding by 8%, 57%, and 20%, respectively, but caused dissimilar changes in their phenology during the growing season. Overall, although ecosystem carbon stocks were not significantly affected by the whole-soil-warming, some processes and variables of the alpine grassland ecosystem showed significant responses. We will continue to monitor these processes and variables to gain a long-term mechanistic understanding of the response of ecosystem carbon cycling to whole-soil-warming in the alpine grassland.
Fine structures of magnetospheric magnetosonic waves: elementary rising-tone emissions and mini harmonics
Authors: Li Jinxing , Bortnik Jacob , Tian Sheng , Ma Qianli
Published: March 2024

The present study uncovers the fine structures of magnetosonic waves by investigating the EFW waveforms measured by Van Allen Probes. We show that each harmonic of the magnetosonic wave may consist of a series of elementary rising-tone emissions, implying a nonlinear mechanism for the wave generation. By investigating an elementary rising-tone magnetosonic wave that spans a wide frequency range, we show that the frequency sweep rate is likely proportional to the wave frequency. Furthermore, we reveal that each elementary rising-tone magnetosonic waves consist of multiple mini-harmonics spaced at O+ gyrofrequency. We reveal that O+ ions can suppress the generation of magnetosonic waves at multiples of O+ gyrofrequency, resulting in the mini-harmonic structure. The commonly observed mini-harmonics indicate an energy transfer between different ion species.
The Analysis of Different Spatial-temporal Rainfall Characteristics and Drought Disaster Risk Assessment in Penghu Area
Authors: Hsin-Wen Pai , Yuan-Chien Lin
Published: March 2024

The Analysis of Different Spatial-temporal Rainfall Characteristics and Drought Disaster Risk Assessment in Penghu Area Keywords: Empirical Orthogonal Function, Wavelet Analysis, Standardized Precipitation Index, Drought Under the impact of extreme climate and the trend of global warming, the frequency of natural disasters has increased, and extreme rainfall and extreme drought events have gradually increased, causing threats to human life, food shortages, and ecological catastrophes. In recent years, with the development of tourism industry in Penghu, the demand for water resources has increased, but available surface water sources are very scarce. At present, Penghu’s freshwater source is mainly seawater desalination, but this method is likely to affect Penghu’s unique coral reef marine ecology.This study uses data mining methods to analyze rainfall characteristics and drought trends. Rainfall characteristic analysis uses empirical orthogonal function (EOF) and wavelet analysis (WA), and drought trend analysis uses the Standardized Precipitation Index (SPI) at different time scales. The results show that the rainfall characteristics of South Penghu Marine National Park and Penghu Island are different, and the rainfall difference between drought years and non-drought years is large. The drought index shows that in recent years, South Penghu Marine National Park is still in a relatively dry state, with a higher drought frequency than Penghu Island and Taiwan Island. The risk of agricultural drought and hydrological drought is high on a medium to long time scale. Therefore, special attention needs to be paid to the rainfall situation in South Penghu Marine National Park.
Remote Sensing Retriving of Dissolved Oxygen Concentration in Aquaculture Ponds in the Guangdong-Hong Kong-Macao Greater Bay Area
Authors: Mao Keming , Yang Xiankun
Published: March 2024

China has been a traditional aquaculture powerhouse, contributing over one-third of the global production. The Guangdong-Hong Kong-Macao Greater Bay Area stands out as a primary region for aquaculture. Pond aquaculture is a significant method employed in this area, benefiting from its geographical advantages with a widespread and numerous distribution of fish ponds within the Greater Bay Area. The primary production units for aquaculture ponds are predominantly household-based, decentralized, and lack a significant intensive production effect. Aquaculture personnel often rely on experiential judgment to assess water quality. In recent years, increased human factors and a lack of effective management in the aquaculture pond industry have exacerbated water pollution issues. This has resulted in a growing severity of water pollution problems, with governmental departments unable to conduct large-scale monitoring of aquaculture pond water quality. Dissolved oxygen serves as a crucial indicator reflecting the water quality of these aquaculture ponds. Only dissolved oxygen concentrations within suitable ranges can facilitate the growth of aquatic products; concentrations that are either too high or too low can adversely affect aquatic product growth. This study utilized Landsat 8/9 OLI satellite images, employing atmospheric correction based on Rayleigh reflectance. It combined machine learning and water body index methods to establish a dissolved oxygen Support Vector Regression (SVR) inversion model (R2=0.67). This model determined the trends in dissolved oxygen concentration changes and spatial distribution patterns in aquaculture ponds within the Greater Bay Area over the past decade. The results indicate that from 2013 to 2023, there was a marginal decrease of 0.04% in dissolved oxygen concentration. Concentrations decreased during 2014-2016 and 2018-2020, while they increased in other years. Seasonally, concentrations were higher in spring and autumn and lower in summer and winter. Summer exhibited the lowest dissolved oxygen concentration throughout the year, with the smallest concentration difference and relatively concentrated numerical distribution. Dissolved oxygen concentrations varied significantly in other seasons. Aquaculture ponds in low latitude coastal areas generally had lower dissolved oxygen concentrations, while those in northern mountainous and upstream river regions had relatively higher dissolved oxygen concentrations.
Subseasonal Predictability of Early and Late Summer Rainfall Over East Asia
Authors: Li Xiaojing
Published: March 2024

Considering the significant differences in the rainfall characteristics over East Asia between the early [May–June (MJ)] and late [July–August (JA)] summer, this study investigates the subseasonal predictability of the rainfall over East Asia in early and late summer, respectively. Distinctions are obvious for both the spatial distribution of the prediction skill and the most predictable patterns, that is, the leading pattern of the average predictable time (APT1) between the MJ and JA rainfall. Further analysis found that the distinct APT1s of MJ and JA rainfall are attributable to their different predictability sources. The predictability of the MJ rainfall APT1 is mainly from the boreal intraseasonal oscillation signal, whereas that of the JA rainfall APT1 is provided by the Pacific–Japan teleconnection pattern. This study sheds light on the temporal variation of predictability sources of summer precipitation over East Asia, offering a possibility to improve the summer precipitation prediction skill over East Asia through separate predictions for early and late summer, respectively.
The wedge-like ion spectral structures in the inner magnetosphere
Authors: Ren Jie , Zong Qiugang , Zhou Xuzhi , Yue Chao
Published: March 2024

Energetic ions from the plasma sheet will be freshly injected into the inner magnetosphere during geomagnetic activities, and exhibit some spectral features named after the shapes of energy bands in the energy-time spectrograms such as the “nose-like” structure,“trunk-like” structure, and ion spectral gap. Using the ion observations from Van Allen Probes launched in 2012, my work revealed the existence of a new ion structures, which is the wedge-like structure of O+, He+, and H+ ions in the inner magnetosphere. The wedge-like structures have the energy range of eV-keV and can penetrate into deep regions (even L
Extensional tectonics at ridge-transform intersections – constraints from micro-seismicity and bathymetric data
Authors: Grevemeyer Ingo , Lange Dietrich , Ruepke Lars , Klauke Ingo , Bienest Anouk , Gómez de la Peña Laura , Ren Yu , Hilbert Helene-Sophie , Li Yuhan , Murray-Bergquist Louisa , Unger Moreno Katharina , Hansteen Thor , Devey Colin W.
Published: March 2024

Fracture zones were recognized to be an integral part of the seabed long before plate tectonics was established. Later, plate tectonics linked fracture zones to oceanic transform faults, suggesting that they are the inactive and hence fossil trace of transforms. Yet, scientist have spent little time surveying them in much detail over the last three decades. Recent evidence (Grevemeyer, I., Rüpke, L.H., Morgan, J.P., Iyer, K, and Devey, C.W., 2021, Extensional tectonics and two-stage crustal accretion at oceanic transform faults, Nature, 591, 402–407, doi:10.1038/s41586-021-03278-9) suggests that the traditional concept of transform faults as being conservative (non-accretionary) plate boundary faults might be wrong. Instead, transform faults are always deeper than the associated fracture zones and numerical modelling results suggest that transform faults seem to suffer from extensional tectonics below their strike-slip surface fault zone. In 2021, we tested this hypothesis by collecting, in a pilot study, micro-seismicity data from the Oceanographer transform fault which offsets the Mid-Atlantic Ridge by 120-km south of the Azores near 35°N. Analysis of 10-days of seismicity data recorded at 26 ocean-bottom-seismometers and hydrophones showed 10-15 local earthquakes per day. Furthermore, a sparse network recorded micro-earthquakes for three months. Joint interpretation of the data shows that earthquakes away from the ridge-transform intersections cluster along the fault trace imaged in bathymetric data and focal mechanisms support strike-slip motion. However, at the ridge-transform intersections seismicity does not mimic a right-angular plate boundary; instead, seismicity occurs below the inside corner and focal mechanism indicate extensional tectonics. In addition, we put published micro-earthquake data from surveys conducted in the 1970 to 1980s from the Oceanographer, Kane and Vema transform fault in a new context by plotting them onto modern swath-bathymetric data. In concert, micro-seismicity supports features found in numerical simulations, revealing that transform faults have an extensional as well as a strike-slip component.
Development of the fine resolution fractional vegetation cover product and its application in urban area
Authors: Song Dan-Xia , Zhong Dantong , He Tao , Gao Shuhang , Chen Ziyi
Published: March 2024

The rapid pace of urbanization has accentuated the need for precise monitoring and assessment of vegetation cover changes within urban areas. Fractional Vegetation Cover (FVC) is an important parameter used to quantify the proportion of land covered by vegetation, providing essential insights into urban vegetation change and phenological dynamics. Traditional methods for estimating FVC, often hampered by limited spatial resolution, struggle to accurately capture the intricate dynamics of urban greenspace. Addressing this gap, our study introduces an innovative approach for generating high-resolution FVC products, aiming to provide a more detailed analysis of urban vegetation cover and quantify the extent to which urban residents are exposed to greenspace. In this study, we established a framework for estimating vegetation cover at a fine spatial resolution by combining high-resolution GF-2 images with 30 m Landsat 8 images. We generated 30 m FVC training data by aggregating 1 m GF-2 FVC data collected from various regions across China. Random Forest (RF) regression, an ensemble machine learning method used for classification and regression, was employed to construct multiple models with different combinations of Landsat spectral and angular features to test the performance of various variables. The model utilizing Landsat surface reflectance and solar zenith angle as inputs proved to be the most accurate, with an R² of 0.979 and an RMSE of 0.041 and was selected for estimating the 30 m vegetation cover. The results showed that when validated using 346 independent ground measurements from 14 sites around the globe, the R² was 0.814 and the RMSE was 0.170. By comparing the Landsat vegetation cover with three satellite-based vegetation cover products over a period of five years for different vegetation types, it was further proven that Landsat vegetation cover has the highest consistency and temporal continuity with other vegetation cover products in coniferous forests, shrublands, and grasslands. Finally, through the instantaneous estimation of vegetation cover in Wuhan City, Hubei Province, the annual average of vegetation cover was obtained. The spatial distribution of vegetation cover was derived, the phenological indicators of urban vegetation were extracted, and the trends in vegetation and its phenology at a 30 m resolution were presented. Our conclusion is that, during 2000 and 2020, urban greenspace coverage has significantly increased, the length of the vegetation growing season has noticeably extended, and human exposure to urban greenspace has risen. In urban environments, the method and application proposed in this study contribute to providing detailed insights into changes in urban greenspace, thereby enabling accurate monitoring and assessment of vegetation cover in urban environments, which is crucial for urban planning and environmental management.
The Seasonal and Diurnal Variation Characteristics of SoilMoisture at Different Depths from Observational Sites over the Tibetan Plateau
Authors: Wang Ge
Published: March 2024

Using observational data of soil moisture from the third Tibetan Plateau Experiment for atmospheric science (TIPEX III), the seasonal and diurnal variations characteristics of soil moisture at different depths of 5–160 cm from seven stations were analyzed, with emphasis on the comparative analysis of the differences of soil moisture between different sites and the differences of the synergistic relationship between soil moisture and temperature. The soil moisture was wet in the southeast and dry in the northwest. The studied sites were Lhari, Biru, Nyainrong, Amdo, Nagqu, Baingoin and Seng-ge Kambab in descending order, according to the soil moisture. The seasonal variation of soil moisture at the different sites showed a significant three-peak structure, which was more obvious in the shallow layer than in the deep layer. The first peak occurred from March to May, which was mainly due to the soil thawing in spring. The other two peaks corresponded to the two rainy seasons in the plateau. Soil moisture was the greatest during this rainy period. The diurnal variations of soil moisture and temperature in Amdo, Nagqu, Nyainrong and Baingoin showed a significant positive correlation in the four seasons. The soil moisture and temperature in Lhari and Biru were significantly positively correlated in winter and spring but negatively correlated in summer and autumn. The profiles of the soil moisture with depth varied greatly at different stations in different seasons. The distribution of soil water content at each observational site did not increase or decrease with depth but showed a certain high aquifer, which might be related to the types of the underlying surface and physical properties of soil. During the summer monsoon period, soil moisture in the shallow layer of 5–10 cm was higher at all observational sites. The spatial distribution of soil moisture in the plateau was more heterogeneous than that in the plain area, and only in the central part of the Tibetan Plateau, the soil moisture varied greatly from site to site. This also indicated that it was unreasonable to only use the soil moisture of several stations to represent the overall soil moisture of the region. The results provided a multi-angle observational basis for the validation of satellite data and parameterization of the numerical model of soil moisture over the Tibetan Plateau.
Assessment of Blue and Green Water Availability in the Upper Ghatprabha River Basin under Climate Change Impacts
Authors: Jain Sanjana , Jain Manoj Kumar
Published: March 2024

The study focuses on assessing the impact of climate change on water balance components in the Upper Ghatprabha River Basin in India. The Soil Water Assessment Tool (SWAT) is utilized to simulate streamflow in the basin. Calibration and validation of SWAT are performed across multiple sites using the Sequential Uncertainty Fitting Algorithm (SUFI 2). Performance assessment relied on metrics such as the Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R2). Future climate projections are based on an ensemble mean of 13 bias-corrected GCM models for the Shared Socioeconomic Pathways (SSP) scenarios SSP245 and SSP585. The simulation of future basin water balance components involves segmenting the entire timeframe into S1 (2015-2040), S2 (2041-2070), and S3 (2071-2100). Projections indicate an increase in maximum and minimum temperatures, with precipitation potentially rising by up to 47% in the basin under the SSP245 scenario by the end of the century. Hydrological simulations reveal increased surface runoff and evapotranspiration under the SSP245 scenario compared to historical data. The percentage change in blue water components under both SSP scenarios shows an increase of more than 50% compared to the historical data. In comparison, that of green water components only increases to a maximum of 8% in all the timeframes (S1, S2 and S3). Notably, the impact of climate change is more pronounced under the SSP585 scenario compared to SSP245. These changes significantly impact the water resources of the Upper Ghatprabha River Basin; necessitating focused attention on future planning and management strategies for water resources.
Laboratory Studies Relevant to the Coupled OH Meinel and O2 Atmospheric Band Emissions
Authors: Kalogerakis Konstantinos
Published: March 2024

The hydroxyl radical plays an important role in the photochemistry of the Earth's mesosphere. The OH Meinel band emission dominates the visible and near-infrared portion of the nightglow spectrum. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen is essential for understanding mesospheric OH emissions and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental methodologies to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Our previous studies have indicated that the total removal rate constant for OH(v = 9) by atomic oxygen at room temperature is more than one order of magnitude larger than that for removal by molecular oxygen. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the mesospheric OH(v) Meinel band emissions. This is a progress report on our experimental studies investigating OH(v ≥ 5) + O vibrational relaxation and the implications for mesospheric nightglow.This work is supported by the NASA Heliophysics Program under Grant 80NSSC23K0694 and the National Science Foundation (NSF) under Grants AGS-2009960 and AGS-2113888.