bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Disaster-causing Heavy Rainfall in Taipei City and Its Application
Authors: Jung Chi-June , Hsiu Radiant Rong-Guang , Kao Yu-Cheng , Chiang Mon-Liang , Hung Wen-Bin , Wang Jing-Ting , Jou Ben Jong-Dao
Published: March 2024

The most challenging weather phenomenon for disaster response in Taipei City is localized short-duration heavy rainfall. The capacity of each administrative district to withstand rainfall intensity varies, leading to incidents of flooding even when the rainfall falls short of the designed protection standard of 78.8 mm/h for drainage systems. To enhance disaster response, the Taipei City Fire Department conducts investigations and reports based on rainfall conditions. By integrating the intelligence and reporting system and raising the dispatching standard from 20 to 40 mm/h, the "Heavy Rainfall Response Process Improvement" project has successfully reduced response operation time and alleviated service burdens, advocating for adopting higher standards.This study explores the correlation between intense rainfall and disaster occurrences, examining thunderstorm events that caused significant flooding in over three administrative districts. The study compares the earliest reported flooding time in each district with the corresponding rainfall, revealing that several districts experienced flooding with less than 60 mm/h of rainfall at the onset, indicating heightened vulnerability. Additionally, the study delves into the relationship between rainfall patterns and disaster potentials. When it accumulates 40 mm of rainfall within 30 minutes, there is a 63% chance of reaching 60 mm accumulation in the following 10 to 20 minutes. This analysis underscores the potential application of cumulative rainfall within the first 30 minutes for predicting subsequent rainfall trends and issuing disaster warnings.
Effect of bedload sheets beyond hydrograph boundary layer on alternate bar morphology
Authors: Tanabe Soichi , Iwasaki Toshiki
Published: March 2024

Sediment supply has several essential roles in downstream river morphology and grain size; however, quantifying the relationship between sediment supply effect and river morphodynamics remains difficult. This is because of our limited understanding of the spatiotemporal scale of the nonequilibrium effect caused by the imbalance between sediment supply and transport capacity on downstream river dynamics. Here, we investigate the morphology of alternate bar with mixture-sized sediment under cycled hydrographs and constant sediment supply. This upstream water and sediment supply condition results in repeated aggradation/degradation and fining/coarsening near the upstream end. Under well-sorted sediment condition, such variation of bed and grain size takes place only limited upstream reach so-called hydrograph boundary layer (HBL). On the other hand, poor-sorted sediment breaks down the concept of HBL, causing a grain-sorting wave such as bedload sheet that migrates beyond HBL. This sorting wave represents a long-distance effect of upstream sediment supply on the downstream river morphology. The amplitude of this sorting wave is generally small, but may affect downstream bar dynamics since previous experimental and numerical studies have indicated that alternate bars with mixture-sized sediment are more unstable to some disturbance than those with uniform-sized sediment. To understand this, we perform the numerical calculation by using a two-dimensional morphodynamic model, iRIC-Nays2DH, to clarify how bedload sheet migrating beyond HBL as a disturbance affects the downstream alternate bar morphology. The computational condition is determined based on the Otofuke River, Japan, a typical gravel-bed river. The river has wide grain size distribution and well-developed alternate bars, so this will be a suitable case to understand the effect of bedload sheet on the alternate bar dynamics. The numerical result shows bed elevation variation during a single hydrograph close to the upstream end corresponding to the HBL, and small-amplitude grain sorting wave migrates downstream beyond HBL. The alternate bars developed slightly downstream of HBL reach so that the upstream alternate bar is continuously affected by the migration of bedload sheet. The bedload sheets cause irregular alternate bars upstream to a certain extent, but this has a limited role in more downstream alternate bar dynamics. This will be because of the much larger sediment storage of bars than small-amplitude bedload sheet. This result may suggest that the bedload sheet can indeed migrate downstream of HBL, but, has a small effect on the downstream alternate bar dynamics.
Voluminous low-temperature S-type granite formation in the New England Orogen, eastern Australia during back arc evolution
Authors: He Xiaofang , Hand Martin , Morrissey Laura J. , Collins William J.
Published: March 2024

Crustal melting leading to the formation of S-type granite is typically considered a characteristic of collisional regimes. However, the formation of S-type granites does not necessarily require overt crustal thickening. Instead, voluminous granite generation can occur where burial of fertile H2O-rich material occurs in high heat flow environments. One obvious setting that has these attributes is rapidly developing back arc regimes. Settings such as these are ideal to generate large volumes of S-granite without necessarily requiring appreciable crustal thickening.The Bundarra and Hillgrove granite intrusions in the southern New England Orogen, eastern Australia are part of an Early Permian garnet/cordierite-bearing S-type granite batholith (>1800km2) generated in a back-arc setting linked to the easterly (outboard) migration of a W-dipping subduction zone. This setting facilitated rapid and thick accumulation of compositionally immature detritus from the active arc and the inboard continent, creating a fertile system for granite genesis driven by back arc high heat flow. Deposition of the precursor sedimentary volume occurred between 360 and 300 Ma, with partial melting and batholithic-scale melting and granite accumulation occurring between ca. 298-288 Ma. Seismic reflection data suggests the currently preserved crustal column in places comprises ~30% granite, with the current level of denudation ranging between ~ 3-5kbar.Ti in zircon and quartz, and zircon saturation temperatures suggest granite-formation temperatures may have been as low as 700-750 °C. Mineral equilibria modelling using protolith compositions considered presentative of the sedimentary protoliths suggest melting at the scale indicated by regional mapping and geophysics is only possible in a water rich environment, either from trapped water that was not expelled during burial in the back arc, or for an external source.The geochemistry of the Bundarra and Hillgrove suites shows significant variability in their maficity. When comparing the modelled magma/melt compositions at different water contents the variation in maficity shows the granites are more mafic than the modelled melt compositions, suggesting much of the mafic content is entrained from the source. This is supported by the occurrence of hexagonal shaped biotite aggregates which contain occasional garnet relics.We interpret that water-fluxed melting played an important role in the genesis of back arc hosted S-type granites in eastern Australia, and it may apply to the genesis of many other S-type granite batholiths. Variable entrainment of the residual mineral assemblage within a cool, hydrous silicic melt can probably explain the compositional range of New England and other S-type granite batholiths.
Global models overestimate streamflow induced by rising CO2
Authors: Wei Haoshan , Zhang Yongqiang , Liu Changming , Huang Qi
Published: March 2024

The global streamflow plays a crucial role in the broader water cycle, intricately linked to human activities, ecology, and agriculture. The rise in atmospheric CO2 has complex effects on global streamflow. In addition to feedbacks to climate change, CO2 impacts on streamflow result from surface changes, including reduced streamflow induced by expanding vegetation and increased streamflow induced by reduced vegetation evapotranspiration due to stomatal closure. Global models, vital for policy planning, predict increased streamflow due to dominant positive impacts of elevated CO2. More than 10 out of 14 global dynamic vegetation models concluded that increased CO2 exacerbated runoff growth over the 1981-2020 period, especially in tropical and temperate regions. Yet, studying four decades of observed streamflow data, we find these models largely overestimate the increase in streamflow induced by elevated CO2, particularly in tropical forest (tropical) and cold forest (cold), pointing to an unexpectedly drier world.
A new framework for water quality forecasting coupling causal inference, time-frequency analysis and uncertainty quantification
Authors: Zhang Chi , Nong Xizhi , Behzadian Kourosh , Campos Luiza , Shao Dongguo
Published: March 2024

Accurate forecasting of water quality variables in river systems is crucial for relevant administrators to identify potential water quality degradation issues and take countermeasures promptly. However, pure data-driven forecasting models are often insufficient to deal with the highly varying periodicity of water quality in today’s more complex environment. This study presents a new holistic framework for time-series forecasting of water quality parameters by combining advanced deep learning algorithms (i.e., Long Short-Term Memory (LSTM) and Informer) with causal inference, time-frequency analysis, and uncertainty quantification. The framework was demonstrated for total nitrogen (TN) forecasting in the largest artificial lakes in Asia (i.e., the Danjiangkou Reservoir, China) with six-year monitoring data from January 2017 to June 2022. The results showed that the pre-processing techniques based on causal inference and wavelet decomposition can significantly improve the performance of deep learning algorithms. Compared to the individual LSTM and Informer models, wavelet-coupled approaches diminished well the apparent forecasting errors of TN concentrations, with 24.39%, 32.68%, and 41.26% reduction at most in the average, standard deviation, and maximum values of the errors, respectively. In addition, a post-processing algorithm based on the Copula function and Bayesian theory was designed to quantify the uncertainty of predictions. With the help of this algorithm, each deterministic prediction of our model can correspond to a range of possible outputs. The 95% forecast confidence interval covered almost all the observations, which proves a measure of the reliability and robustness of the predictions. This study provides rich scientific references for applying advanced data-driven methods in time-series forecasting tasks and a practical methodological framework for water resources management and similar projects.
Depth-resolved model for debris flows based on a two-phase fluid
Authors: Tang Jinbo , Cui Peng , Wang Hao , Lei Yu , Wang Yu
Published: March 2024

Debris flows are prevalent natural hazards in mountainous regions, posing threats to human safety and resulting in property damage. Recent research has focused increased attention on characterizing the dynamic properties of these flows, especially in the vertical direction. The present study puts forth a mathematical model to describe the physics of debris flows. Specifically, concentration-weighted averaging is employed to represent the mass and momentum balance equations of the bulk granular-fluid mixture. Furthermore, an evolution equation for the slip velocity between the granular solid and liquid phases is derived in order to capture the separation between these constituents. The model determines the particle pressure based on frictional-collisional relations and the fluid stress via a Herschel-Bulkley rheological formulation. The coupled differential equations are solved numerically using a two-step finite difference projection method. The free surface profile is tracked using a volume of fluid approach. Favorable comparisons with experimental measurements validate the numerical model. Finally, analyses provide insight into the influence of the slip velocity on the dynamics of granular-liquid flows.
Development of stadium-specific numerical forecast guidance for weather forecast for the 2024 Gangwon Winter Youth Olympic Games
Authors: Kim Yeon-Hee , Cho Eunju , Jang Sungbin , Kim Junsu , Bok Hyejeong , Kim Seungbum
Published: March 2024

The 2024 Gangwon Winter Youth Olympic Games (GANGWON 2024) will be held in the province of Gangwon in the Republic of Korea from January 19 to February 1, 2024, which already hosted the Olympic Winter Games PyeongChang 2018. In order to successfully host these first Winter YOG to be held in Asia, which will be held for the first time in Asia, it is necessary to provide customized weather information for decision-making in game operation and support in establishing game strategies for athletes and their teams. Accordingly, the Korea Meteorological Administration develops point-specific numerical forecast guidance for major stadiums and provides it to the field to support successful hosting of YOG and improvement of performance. Numerical forecast guidance is the final data delivered to consumers or forecasters as post-processed numerical model data that has been corrected by applying altitude correction and statistical methods to produce highly accurate forecasts. For a total of 13 forecast elements (temperature, minimum/maximum temperature, humidity, wind direction/speed, precipitation, new snow cover, sky conditions, precipitation probability, precipitation type), we developed user-customized numerical forecast guidance specialized for competition points  (Gangneung Olympic Park, Pyeongchang Alpensia Venue, Biathlon Center, Olympic Sliding Center departure/arrival, Wellyhilli departure/arrival, High1 departure/arrival). Through the process of Perfect Prognostic Method (PPM), Model Output Statistics (MOS), optimization, and optimal merging, the systematic errors inherent in the numerical model are removed, and the optimal data (BEST) with improved forecasting performance is provided as customized numerical forecast guidance specific to stadium locations.  In the prediction performance evaluation for the period of December 2023, the accuracy (improvement rate) compared to the average of available models was temperature 1.49℃ (18%), humidity 12% (25%), wind speed 1.87m/s (33%), and visibility 12.8km (17%).
The Development of precipitation model modifed with ECMWF IFS and XGBoost and its performance verification
Authors: Cho Eunju , Kim Yeon-Hee , Kim Seungbum , Kwon Young Cheol
Published: March 2024

This study was conducted to develop a modified precipitation model for its amount and existence by combining machine learning method, Extreme Gradient Boosting(XGBoost), with ECMWF IFS(Integrated forecasting system) and, finally, estimate the related performance.According to the analysis of regional precipitation characteristic, prior to its development, the ratio of precipitation existence was various on a basis of a forecast’s district and its season. These different patterns on each district makes it necessary to develop the regional and seasonal model respectively.And, the first attempt at the machine learning showed the importance of each feature as input-variables, as a result of which cloud physics-related features, for example large-area precipitation, total precipitation, visibility and what not, proved so significant. However, the insufficient amount of these feature’s data seemed to result in overfitting. And therefore, the feasible features, except for cloud physics-related things, of IFS data were used. In addition, auxiliary features and their gradient for every lead-time were calculated and added: relative vorticity, divergence, equivalent potential temperature, main 6 patterns for Korean summer and so on. The number of features amounted to around 144 with which for the 9-year training set, 2013~2021, based learning to be conducted regionally, followed by using validation-set of 2022.As a result of validation for precipitation existence and its amount up to 135 hours ahead on the 10 regions at 00UTC in summer of 2022, Critical Success Index(CSI) was more improved by 10.3% than before. Accuracy(ACC) for each lead-time rose by 6% and its fluctuation also decreased. And the correction by this machine learning alleviated the overfitting trend of precipitation forecast amount produced by the original model, and improved correlation and linearity between observation and forecast. In particular, while the machine learning prevailed over the original model up to 100 hours ahead, from then on, both of them showed similar performance or that of the former was downward slightly. If the above-mentioned cloud physics features are used to further sharpen machine learning technique, its performance should be enhanced more and more.
Exploring pathways to sustain a stable transboundary cooperation for Lancang-Mekong River Basin under changing hydrological conditions
Authors: Zhang Bingyao , Li Yu , Zhang Chi
Published: March 2024

Transboundary river cooperation is crucial to maintaining regional security and achieving sustainable development. However, the stability of cooperation is challenged by changing external hydrological conditions, hindering the enormous benefits sharing foreseen from basin-wide cooperation. This paper focuses on the solution idea and pathway on how to lead a stable cooperation in the Lancang-Mekong River Basin (LMRB). The Nash equilibrium concept is introduced to illustrate the premise of stable cooperation, in which no party has the motivation to defect under all possible situations. Considering the passive acceptance of the hydrological conditions, we suggest that proactive negotiation in the electricity trade provides a viable pathway for stable cooperation. Following this solution idea and pathway, we present the Lancang-Mekong River Basin as a case and propose a normalized dual water-electricity cooperation (NDWEC) framework. The impacts of hydrological uncertainties on cooperation and the corresponding electricity trade negotiation space are investigated within the NDWEC framework. The negotiation space implies thresholds of acceptability, consisting of the bottom line (the starting point of negotiation) and the ceiling (the expectations of the negotiation). The results from the negotiation space show that Thailand and Vietnam are active advocators with considerable benefits in basin-wide cooperation. In contrast, Laos and Cambodia face limited negotiation space, suggesting the need for additional incentives from other interested areas, such as financial channels. Moreover, stress-tests under future climate models indicate a warning of approximately 3~6% failure risk in negotiations. This work can provide valuable insights into the decision-making processes of riparian countries in today’s changing world.
Revisiting Tabular Machine Learning and Sequential Models to Advance Climate Downscaling
Authors: Hobeichi Sanaa , Shao Yawen , Rampal Neelesh , Bittner Matthias , Abramowitz Gab
Published: March 2024

Recent advancements in the empirical downscaling of climate fields using Machine Learning have predominantly leveraged computer vision approaches. These methods treat a climate field as an image channel, applying image processing techniques to automatically extract features for the downscaling model from its latent space embeddings. In contrast, this work aims to revisit and validate the potential of tabular and sequential models in the context of grid-by-grid downscaling, where each grid cell in a map is individually downscaled and input features for the downscaling model are selected manually by a climate expert. We present downscaling results for precipitation and evapotranspiration using three distinct models: Long Short-Term Memory (LSTM), Multi-layer Perceptron (MLP), and a hybrid approach that combines Linear Regression with Random Forest. Our discussion includes the setup and optimization strategies for these models to enhance their ability to capture extremes. The merits of this grid-by-grid approach are highlighted, focusing not only on performance and effectiveness in preserving spatial features but also on its flexibility, spatial transferability, ease of model fine-tuning, and training efficiency.
POC export fluxes across the Seychelles-Chargos Thermocline Ridge in the western Indian Ocean based on 234Th as a tracer
Authors: Seo Junhyeong , Kim Intae , Lee Hyunmi , Kim Suk Hyun
Published: March 2024

We investigated the export flux of particulate organic carbon (POC) using 234Th as a tracer in the western Indian Ocean along 60°E and 67°E transects in 2017 and 2018. The Seychelles-Chagos Thermocline Ridge (SCTR), where production is relatively high due to nutrient replenishment by upwelling of subsurface water, was observed at 3°S – 12°S in 2017 and 4°S – 13°S both 60°E and 67°E in 2018. POC fluxes in 2017 showed no differences between the SCTR and non-SCTR regions. However, in 2018, the POC fluxes in the SCTR regions (8.52 ± 7.89 mmol Cm–2 d–1) were one order of magnitude higher than those observed in the non-SCTR regions (0.63 ± 0.07 mmol C m–2 d–1), which appeared to be related to the strong upwelling of subsurface water. These POC fluxes were comparable to those observed under bloom conditions, and thus, are important for estimating the efficiency of carbon sequestration in the ocean.
Numerical modeling and analysis of GNSS carrier-phase diffraction error in high occlusion environments
Authors: Xi Ruijie
Published: March 2024

In city canyons or natural valleys, diffraction effect occurs when Global Navigation Satellite System (GNSS) signal approaches to the edge of buildings, trees and slopes etc., resulting in a large diffraction error, which is the dominant error source for the low ambiguity fixing rate (AFR), the reduction of positioning accuracy and the frequent gross error in real-time kinematic positioning and high precise static positioning. However, the theoretical formula derivation and the numerical modeling of the diffraction error has been rarely studied, and the diffraction error mostly processed with the multipath processing methods in present. Therefore, in this study, we derived the theoretical formula of the diffraction error based on ray-tracing, i.e., using satellite-reflector-antenna geometries to model the diffraction errors according to the theory of diffraction effect. After that, we estimated and extracted the realistic diffraction error from the GNSS data collected in high occlusion environments to study the time-varying characteristics of diffraction errors and the effectiveness of the diffraction numerical modeling formulas. The results show that the time-varying characteristics of diffraction error can be precisely simulated with the vertical and horizontal diffraction formulas proposed, and the diffraction error estimated with double-differencing (DD) model generally has a linear character of positive increasing or negative decreasing monotonously, and according to the sign of the error, we can identify which station the diffraction effect occurs at. The amplitude of the diffraction error could be larger than 50mm to 200mm, and even larger, which is extremely larger than the multipath effect. Large diffraction error usually corresponds to a low SNR, with less than 40 dB/Hz, and the differenced SNR of the reference station and the monitoring station is generally greater than 5 dB/Hz. Based on this, we proposed the diffraction error removal strategies with SNR mask and SNR differencing threshold between stations. The results of GNSS data processing in two groups of high-occlusion complex environments show that the SNR mask and SNR differencing strategies can effectively eliminate the influence of large diffraction errors. The single epoch AFR can achieve to more than 90%, and millimeter-level positioning accuracy can be realized in the real-time kinematic positioning mode. The SNR differencing strategy is more effective in practical monitoring applications. The numerical modeling formulas and conclusions in this study will have important practical applications in high-precision positioning area, such as IGS data processing, deformation monitoring and vehicle navigation, etc.
Advanced Lithofacies Analysis by Using X-Ray Computed Tomography
Authors: Wu Yen-Hsi , Huang Jyh-Jaan , Yu Neng-Ti , Yen Jiun-Yee , Chyi Shyh-Jeng , Chen Jia-Hong
Published: March 2024

Lithofacies, defined as distinctive assemblages of sedimentary characteristics, necessitate a comprehensive understanding of their past depositional environments to facilitate paleoenvironmental reconstructions, resource explorations, and effective hazard assessments. To unravel the complexities of texture variety and other sedimentary features, along with physicochemical properties, conventional methods such as core description, grain size analysis, and well logging have been widely utilized. However, these approaches have limitations due to observer-dependence, time-consuming processes, discrete sampling, and the restriction to subsurface observations, which may impede the accurate distinction of lithofacies. X-ray Computed Tomography (X-ray CT), a rapid, non-destructive, and high-resolution technique, offers an unbiased and continuous approach. It provides three-dimensional visualization of samples and allows for qualitatively and quantitatively statistical analysis in stratigraphy, addressing the limitations of conventional methods. In this study, X-ray CT was employed to examine five sediment cores containing diverse sedimentary features and distinctive materials near Dapeng Bay in southwestern Taiwan. The research aimed to evaluate the feasibility of X-ray CT in characterizing different lithofacies within this region through a structured three-step workflow, involving systematic X-ray CT scanning, extraction of CT-derived intensity and statistical data, and analogy of lithofacies of cores with modern samples of known depositional conditions. The comparative analysis of CT-derived parameters within the cores was used to distinguish the features of different lithofacies. Furthermore, organic and biological substances such as charcoals and shells were observed and defined by given radio-density, characterizing other unique lithofacies with their presence combination. The classified lithofacies in CT-derived parameters may also correspond to specific depositional processes or events. By demonstrating how the application of X-ray CT quantitatively aids in characterizing and distinguishing various lithofacies, this research may ultimately contribute to providing an analogical foundation for subsequent lithofacies analysis within comparable sedimentary settings and extended time spans in future research.
Submerged aeolian dunes on the flat-topped Dokdo seamount in the East (Japan) Sea, Korea
Authors: Bahk Jang-Jun , Kim Soo-Jin , Kim Chang Hwan , Sohn Young Kwan , Park Chan Hong
Published: March 2024

This study examines subaqueous dunes located on the southern periphery of the flat top of Dokdo Seamount at water depths from 120 to 170 meters, where the present ocean currents are incapable of generating such large bedforms. To determine their origin, we conducted a comprehensive analysis of the geomorphic characteristics using high-resolution multi-beam bathymetry and the grain-size characteristics of seafloor sediments. The analysis of the dune spacing in relation to height, as well as their migration and growth pattern, indicates that the Dokdo subaqueous dunes (DSDs) originally formed as aeolian dunes. These were shaped by northerly winter winds that carried sands from the wave erosion surfaces on the northern part of the flat top. The DSDs are believed to have transitioned to their current submerged state without experiencing significant erosion or reactivation. Considering the variations in the Plio-Pleistocene global mean sea level, we estimate the possible subsidence rate of the flat top to be approximately 130 m/myrs, aligning with the conditions required for the formation of DSDs. This study highlights how relict features such as submerged aeolian dunes on seamount summits can be utilized to precisely estimate the subsidence rate of oceanic volcanoes.
Sensitivity analysis of coastal storm surge forecasting using NEMO-based CTSM model
Authors: La Nary , Chang Pil-Hun
Published: March 2024

The present study introduces a high-resolution Coastal Tide/Storm surge model (CTSM). Recently, the NIMS (National Institute of Meteorological Sciences) developed the CTSM, based on the NEMO ocean model to enhance forecasting capabilities for sea conditions and storm surges. The CTSM is constructed with a two-dimensional barotropic sigma coordinates and has a 1 km horizontal resolution. It consists of Tide/Surge model and Tide model, and their residual is used as surge forecasts. The surge forecasts are then added to the harmonically predicted tides to give forecasts of total water level at the 30 tidal stations around Korea Peninsula. Based on the sensitivity studies, the constant values of 0.0275 and 1024 hPa are adopted as the Charnock coefficient, bottom friction and reference pressure of the model, respectively.In addition, this study investigated the effect of temporal and spatial variations of Charnock coefficient on the surge forecasts during Typhoon HINNAMNO, which caused substantial damage to the Korean Peninsula in 2022. For this, the 2-D Charnock coefficients derived from an operational Coastal wave model are added to the CTSM. It was found that the Charnock values generally exceeded the model’s constant value of 0.0275 during typhoon period. This alteration in Charnock coefficient impacts on the surge forecasts especially near the coastal regions, showing about 10% increase in the sea level.
Thermohaline Circulation Determines the Multi-centennial Variability of Earth's Climate System
Authors: An Fengli , Tong Mingjun , Yang Haijun
Published: March 2024

Long-term proxy data have shown that there is significant multi-centennial variability in Earth's climate system. However, the causes and mechanisms of this variability are still a major scientific problem for climate scientists and archaeologists. From the middle of the Holocene until the Industrial Revolution, there was little change in the Earth's external forcing, so it is important to study the long-term natural oscillations of our climate system during this period. In our research, we designed a series of experiments using CESM1.0 to explore the sources of multi-centennial variability of climate system. In some experiments, the thermohaline circulation was turned off to see if its presence would affect the oscillation of climate system. We finally conclude that thermohaline circulation is likely to determine the multi-centennial variability of Earth's climate system.
Progressive ocean acidification will reduce foraminiferal shell volume and density: results from laboratory experiments using microCT analysis
Authors: Kuroyanagi Azumi , Irie Takahiro , Kinoshita Shunichi , Kawahata Hodaka , Suzuki Atsushi , Nishi Hiroshi , Takashima Reishi , Fujita Kazuhiko
Published: March 2024

The rapid increase in anthropogenic atmospheric CO2 partial pressure have resulted in a decrease in the pH of seawater. Calcifying organisms generally respond negatively to ocean acidification. Foraminifera are one of the major carbonate producers in the ocean, however, whether calcification reduction due toocean acidification affects either foraminiferal shell volume or density, or both, has yet to be investigated. In the study, asexually reproducing specimens of Amphisorus kudakajimensis, a dinoflagellate endosymbiont-bearing large benthic foraminifera (LBF), were cultured under different pH conditions (pH 7.7–8.3, NBS scale) and determined their shell volume and density using micro X-ray computed tomography (microCT). The results showed that both the volume and density of the foraminiferal shells decreased with lowering pH. This suggests that changes in seawater pH would affect not only the quantity (i.e., shell volume) but also the quality (i.e., shell density) of foraminiferal calcification. Previous LBFs culturing study have reported that temperature affects only the shell volume, not the density. We proposed that pH and temperature affect these growth parameters differently because 1) they have differences in the contribution to the calcification process (e.g., Ca2+-ATPase and Ω) and 2) pH mainly affects calcification and temperature mainly affects photosynthesis. It implies that shell volume and density of LBFs can be considered reliable proxies for pH and temperature. Our findings also suggest that, under the IPCC RCP8.5 scenario, (pCO2 = 1250 ppm and global mean temperature +3.7°C in 2100), both ocean acidification and warming will have a significant impact on reef foraminiferal carbonate production by the end of this century, even in the tropics.
The Feasible Study of Detecting High-Degree Coseismic Gravitational Changes
Authors: Ji Yuting , Tenzer Robert , Tang He , Sun Wenke , Lu Wei
Published: March 2024

Aiming to detect the high-degree coseismic deformation of the gravitational anomaly. Gravity Recovery and Climate Experiment (GRACE) is designed as satellite-to-satellite tracking (SST) to recover the time-varying gravity field, and Gravity Field and Steady State Ocean Circulation Explorer (GOCE) carries a set of satellite gravity gradiometry (SGG) to obtain the gravity gradient change. As the GOCE mission directly measures the gravity gradient change which is a high-frequency physics, it contains unique short-wavelength information that GRACE lacks. The SST and SGG are combined to recover the coseismic gravitational deformation up to degree 200, although the SGG was originally designed to recover static fields with high precision. The least squares spectral combination method is used in our study to combine two kinds of data in a spherical harmonic domain. The approach of detecting the high-degree coseismic gravitational deformation is proposed though the current SGG data are not accurate enough to extract coseismic information. Coseismic gravitational deformation in four independent seismic sources is calculated to discuss the minimum requirement of the observation based on the spherical earthquake dislocation. Furthermore, with the remarkable improvement of the accuracy of GRACE-FO, the next-generation gravity mission will probably provide sufficient precision to allow us to obtain high-degree gravitational deformation of the coseismic.
Adaptive sidelobe suppression to mitigate interference from hard targets in EISCAT_3D
Authors: Hashimoto Taishi
Published: March 2024

EISCAT_3D is an international research infrastructure consisting of multiple phased-array incoherent-scatter radars in the northmost areas of Norway, Finland, and Sweden. Since EISCAT_3D is capable of rapid and flexible beam steering with a high transmission power, it is considered to be potentially dual-use, as it could be used to track any objects in orbit, including military satellites. Hence, the radar system has a software component that automatically filters out the echoes from hard targets in real-time, called Hard Target Echo Removal (HTER). There are many satellites and space debris in orbit nowadays, and a large amount of data would be discarded if the HTER procedure was too simple just to throw data packets with hard target echoes.Meanwhile, each antenna array of EISCAT_3D is composed of multiple receivers, enabling adaptive array signal processing. The direction of arrivals for the incoherent scatter and interference from hard targets would be different, as the former comes from the main lobe while the latter from the sidelobe; hence, the interference would be efficiently suppressed with the directionally-constrained minimization of power (DCMP) approach with a constraint to the loss of the signal-to-noise ratio for the incoherent scattering signal.In this presentation, the effectiveness of the adaptive array signal processing is demonstrated on a simulation with realistic settings of the standard experiment of the EISCAT_3D to mitigate the number of discarded data with the HTER processing.
Generation of the Equatorial Intermediate Current in the eastern Pacific Ocean
Authors: Terada Yusuke , Masumoto Yukio
Published: March 2024

It has been shown that the Equatorial Intermediate Current (EIC) in the Pacific Ocean, which is westward current along the equator at intermediated depth (from 500m to at least 2000 m), has basin wide zonally uniform structure. In addition to the EIC, intraseasonal variability (ISV) has also been observed near the equator at 1000 m depth with significant amplitude in the eastern Pacific Ocean. Although this intermediate ISV in the eastern basin is considered as an energy source for the EIC, the origin of the intermediate ISV and its relation to the EIC in the Pacific Ocean are still open questions. In this study, we use the 10-day mean horizontal velocity obtained from drift data of the Argo floats and the temperature data from Tropical Atmosphere-Ocean (TAO) moored array in the equatorial Pacific for a period from 2010 to 2022 to investigate the relationship among the EIC, the ISV at the depth of 1000 m, and the ISV in the upper layer.The meridional component of eddy kinetic energy (V-EKE) at 1000 m depth depicts large intraseasonal variability with a period of about 30 days in the equatorial eastern Pacific, showing a significant seasonality and interannual amplitude modulation. Temperature time series above 500 m depth shows the large amplitude ISV along the equator with the meridionally anti-symmetric structure, whose phase (energy) propagates upward (downward). The surface ISV signal also indicates significant seasonal and interannual variation in its magnitude, which has the highest correlation with the ISV at 1000 m depth at a time lag of 3 months. These results suggest that the ISV at a depth of 1000 m is provided by the upper layer ISV through downward propagating Yanai wave, which takes about 3 months to reach 1000 m depth from the upper layer.Argo-based zonal velocity in the equatorial Pacific Ocean is found to be westward during most of the high V-EKE season, and its magnitude varies on semiannual to interannual time scales. This suggests that intermittent Yanai wave propagation generates a westward flow at 1000 m depth, which could contribute to the generation of the EIC. Furthermore, comparison of results from two numerical simulations of idealized box ocean with or without eastern basin ISV indicates that downward propagating Yanai wave in the eastern Pacific Ocean generates westward flow locally at the intermediate depth. This may explain the observed basin-scale zonal extent of the EIC, which is unique to the Pacific Ocean. Influences of the realistic topography on the ISV and EIC at the intermediate depth will also be discussed.
Impact of Prognostic Graupel Density on Simulated Precipitating Convections
Authors: Park Sun-Young , Lim Kyo-Sun Sunny , Kim Kwonil , Lee Gyuwon , Milbrandt Jason A.
Published: March 2024

Ice particles in cloud microphysics schemes are traditionally categorized as ice crystals, snow, graupel, and/or hail. Each category is defined by static parameters that determine density, diameter-mass relationship, and diameter-fall speed relationship. Several previous studies have reported considerable sensitivity in simulated precipitation systems based on these fixed parameters. This study introduces a prognostic approach for graupel density in the Weather Research and Forecasting (WRF) Double-Moment 6-class (WDM6) microphysics scheme, based on the work of Milbrandt and Morrison (2013). This allows graupel density to vary from 100 to 900 [kg/m3]. The modified WDM6 is tested for idealized squall line and winter snowfall cases over the Korean Peninsula. In the idealized squall line case, simulation results reveal variant graupel density in time and space, according to the evolution of squall line. For winter snowfall cases, simulations using the modified WDM6 show improved statistical skill scores, such as the root mean square error and bias, compared to the original WDM6, mitigating the positive precipitation bias simulated in the original WDM6. The modified WDM6 increases surface graupel amounts and decreases graupel suspended in the atmosphere due to faster sedimentation of graupel. Therefore, the major microphysical processes that generate graupel are influenced, subsequently reducing surface snow and precipitation over mountainous regions. Importantly, the modified WDM6 adeptly captures the relationship between graupel density and fall velocity, as verified by 2D video disdrometer measurements. *This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant no. RS-2023-00272751).
Double-moment approach for snow and graupel in the WDM6 scheme and its effects on simulated precipitation
Authors: Kwon Juhee , Park Sun-Young , Lim Kyo-Sun Sunny , Kim Kwonil , Lee Gyuwon
Published: March 2024

The Weather Research and Forecasting (WRF) Double-Moment 6-class (WDM6) microphysics scheme only predicts the number concentrations for CCN and liquid-phase hydrometeors such as cloud water and rain. Although the double-moment approach for the cloud ice is recently introduced in the WDM6 scheme by Park and Lim (2023), the single-moment approach, in which only mixing ratio is prognosed, is still employed for solid-phase precipitating hydrometeors such as snow and graupel. In this study, the double-moment approach is introduced to WDM6 for all hydrometeors by adding prognostic number concentration of snow and graupel. To evaluate the effects of prognostic snow and graupel number concentrations, simulated results between the new and original versions of WDM6 scheme are compared. The four summer-precipitating (cold-type and warm-type; Kim et al. 2019) and seven winter-precipitating convection cases (cold-low type and warm-low type; Ko et al. 2022) are selected to evaluate the new scheme. In comparison to the original WDM6 scheme, the new scheme exhibits increased snow mixing ratio, except for cold-type summer cases. Additionally, the new scheme reduces the graupel mixing ratio and rain number concentration for all cases. In the new scheme, the raindrop size becomes larger due to the reduced rain number concentration, which is more consistent results with the observation data from 2DVD. Furthermore, larger raindrop size in the new scheme makes the evaporation inefficient. Therefore, the new scheme produces more surface precipitation than the original one. Meanwhile, among total 11 cases, the new scheme improves the equitable treat score (ETS) for eight cases and probability of detection (POD) for seven cases. *This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government. (MSIT) (RS-2023-00208394)
Development of wildfire detection and trajectory tracking system using scanning LiDAR
Authors: Lee Dasom , Kim Kwanchul , Kim Seong-min , Park Jeong-Min , Lee Gahye , Kim Young J.
Published: March 2024

Recently, several huge wildfires in South Korea caused record-breaking damage and casualties. In addition, wildfire occurrence and the amount of damages showed an increasing trend from the 1970s to the 2020s. Moreover, wildfires have become a major concern for the public and key ministries. Thus, the Korean government has been operating various wildfire observation systems using watch towers, CCTV, sensors, observers, etc. However, these systems have spatiotemporal and technical limitations such as short effective distances and discontinuous monitoring. Despite remarkable advances in wildfire detection, it remains challenging to early detect rapidly long-range wildfire events. Here, we developed equipment for early wildfire detection based on scanning Light Detection and Ranging (LiDAR) as a proof of concept to fill that void. Existing scanning LiDAR is used to track and monitor aerosol plumes providing multi-dimensional views of atmospheric layers. An early wildfire detection system using scanning LiDAR has improved for detection of wildfire smoke within 15 minutes with an enhanced spatial distance over a 10km radius and contained both eye safety function and trajectory tracking for point of ignition using HYSPLIT-based Emissions Inverse Modeling System for wildfires (HEIMS-fire).  We showed that the enhanced system continuously detected fire and smoke in rural areas during the day and night. The developed scanning LiDAR system can likely be used for early wildfire detection to prevent large-scale disasters.Acknowledgement: This research was supported by a grant (2023-MOIS-20024324) of Ministry-Cooperation R&D Program of Disaster-Safety funded by Ministry of Interior and Safety (MOIS, Korea).
Gaseous Nitrophenols sources and their contribution to HONO formation in an urban area
Authors: Ahmed Morshad , Rappenglueck Bernhard , Ganranoo Lucksagoon , Dasgupta Purnendu K
Published: March 2024

Nitrophenols (NPs) are compounds that comprise of hydroxyl (-OH) and nitro (-NO2) functional groups attached to at least one aromatic ring. NPs have significant impacts on human health, climate, and atmospheric chemistry. Despite numerous measurements of particulate NPs, little is still known about their gaseous atmospheric sources, chemistry, and fate. In this study, four gaseous NPs - 2,4-dinitrophenol (2,4-DNP), 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), and 2-Methyl-4-nitrophenol (2-Me-4-NP) were continuously monitored during late spring in an urban area of Houston, Texas. Among the four NPs, 4-NP showed the highest abundance, followed by 2-Me-4-NP, 2-NP, and 2,4-DNP, with average concentrations of 0.47 ± 0.12 ppt, 0.41 ± 0.16 ppt, and 0.27 ± 0.09 ppt, respectively. Utilizing the Positive Matrix Factorization (PMF) model, seven sources: industrial NPs, secondary formation, phenol sources, acetonitrile source, natural gas/crude oil, traffic, and petrochemical industries/oil refineries were identified with NPs’ contributions to each factor of 83.3%, 6.6%, 3.3%, 3.2%, 2.0%, 0.9%, and 0.7%, respectively. A zero-dimensional Atmospheric Chemistry (AtChem2) box model was used to simulate the observed 2-NP and 2,4-DNP. The model revealed a 50.0% and 70.0% contribution from JNO2, aligning with measured 2-NP and 2,4-DNP, respectively. This resulted in a nitrous acid (HONO) production of 7.5 ± 2.5 ppt/h between 06:00 and 18:00 Central Standard Time (CST) from both NPs. An extrapolation including other known NPs suggests a maximum HONO formation of 13.8 ppt/h, still magnitudes lower than other known HONO formation processes. Nevertheless, it represents a non-negligible fraction and should be considered in areas with substantial primary NPs emissions, and the corresponding reaction mechanisms should be included in any such model. Combining PMF analysis with a photochemical box model provides identification of NPs sources and their atmospheric impact on HONO formation, offering policymakers insights for implementing effective control measures.