bluuebunny/crossref_metadata_2025 huggingface dataset:
Overview of Airborne Field Campaigns under TEMPO for Calibration and Validation of Trace Gas and Aerosol Products
Authors: McDonald Brian , Cooper Owen , Warneke Carsten , Schwantes Rebecca , Rollins Andrew , Baidar Sunil , Brown Steven ,   AEROMMA / CUPiDS cal/val team
Published: March 2024

The North American component of the Geo-Ring for Air Quality, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument, began collecting measurements on August 2, 2023. Multiple airborne field-intensives were conducted over the US during this TEMPO first-light period, including the NOAA Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) and Coastal Urban Plume Dynamics Study (CUPiDS) campaigns, coordinated with the NASA Synergistic TEMPO Air Quality Sciences (STAQS) campaign. The North American cities targeted included New York City, Los Angeles, Chicago, and Toronto. Here, we present an overview of the AEROMMA / CUPiDS collected summer 2023 datasets, relevant for calibration and validation activities of TEMPO, including for ozone (O3), nitrogen dioxide (NO2), formaldehyde (CH2O), sulfur dioxide (SO2), aerosol optical depth (AOD), and aerosol layer height (ALH). Ground-based lidar and airborne in-situ vertical profiling by the NASA DC-8 and NOAA Twin Otter aircraft are available for evaluating TEMPO Level 2 O3 profile products (tropospheric and 0-2 km column retrievals). Airborne measurements of NO2 (photolytic conversion of NO2 into NO followed by laser-induced fluorescence, cavity enhanced spectroscopy, and multi-axis differential optical absorption spectroscopy (MAX-DOAS)) are available for evaluating TEMPO Level 2 NO2 vertical column density products. Airborne measurements of formaldehyde and glyoxal (in-situ and MAX-DOAS remote sensing) can be evaluated similarly as other volatile organic compounds (VOCs). Lastly, a wide array of aircraft-based in-situ measurements of composition, size distribution, optical properties can be utilized to derive aerosol optical depth (AOD) and aerosol extinction profiles for evaluating TEMPO AOD and ALH products, along with TROPOMI and stereoscopic aerosol layer height products from GOES-16/18. Preliminary evaluation of TEMPO NO2 will be presented as an initial calibration / validation test case, employing best practices to facilitate direct comparisons between airborne data with TEMPO Level 2 observations.
N2O5 heterogeneous uptake on secondary organic aerosol: the effect of organic coating thickness, relative humidity and phase state
Authors: Li Jiayin , Xie Shuyang , Xu Hengyu , Lu Keding
Published: March 2024

The heterogeneous uptake reaction of dinitrogen pentoxide (N2O5) has a great effect on generation of soluble nitrate, nocturnal atmospheric chemistry and regulating NOx. Organic matter is one of the important components of atmospheric particles, and has been proved that can significantly affect the N2O5 heterogeneous uptake coefficients (γ(N2O5)). In this study, an aerosol flow tube system was used for γ(N2O5) measurements on ammonium sulphate aerosols ((NH4)2SO4, AS) and three kinds of core-shell structured secondary organic aerosols (SOA), and explored the effects of relative humidity (RH), phase state and organic coating thickness on γ(N2O5). Three kinds of SOA with core-shell structures were generated successfully by seed particle AS, organic gas (α-pinene, isoprene and toluene) and O3, and characterized by a scanning mobility particle sizer (SMPS) and TEM. The SOA yields, i.e., organic coating thicknesses, of the three organics were ranked, given the same organic gas concentration was α-pinene (17.1±2.2, 4.8 ppm) ＞ isoprene (4.7±0.04, 4.8 ppm) ＞ toluene (1.3±0.7, 4.8 ppm). The experimental results showed that the γ(N2O5) on AS were in the range of 0.002~0.017 (RH=1~50%), whereas that of SOA were between 3.7×10-5~2.6×10-3 (RH=30~50%), and the order of γ(N2O5) at the same RH was isoprene SOA＞ toluene SOA＞ α-pinene SOA. γ(N2O5) of the SOA was reduced by 1-3 orders of magnitude when compared with that of AS, which suggests that organic coating significantly inhibits the diffusion of N2O5 on the surface and in the bulk phase of particles. However, the γ(N2O5) of these three SOA were not completely correlated with the organic coating thickness. The organic coating thickness of two BVOCs showed a nonlinear negative correlation with γ(N2O5) (R2＞0.9), while toluene SOA with the thinnest coating thickness greatly inhibited γ(N2O5) due to its greater influence on particle hygroscopicity. Therefore, due to the large number of organic species, it is not possible to generalize the degree of inhibition of γ(N2O5) only by coating thickness. It is necessary to further consider the influence of properties and structures of organics in the future, and widely applicable parameters for evaluating the effect of organic effect need to be proposed, so as to improve the accuracy of γ(N2O5) estimation.
Behavior of Green Production Technology and Impact on Technical Efficiency——Evidence from China's Apple Growers
Authors: Han Chenxi , Liu Jundi
Published: March 2024

Under the common requirements of ensuring food security and agricultural green development goals, how to explore a way of coordinated development of cultivated land protection and utilization, and effectively achieve "storing grain in the land and storing grain in technology" is the focus of sustainable agricultural development in China. Based on the field survey data of 233 apple growers in typical apple growing areas of Shaanxi and Shanxi in China, this paper used the Super-SBM model to measure agricultural technical efficiency and the propensity score matching (PSM) method to analyze the impact of green production technology adoption behavior on agricultural technical efficiency, and the dimension of green production technology adoption was further expanded to analyze the impact of different technology adoption conditions on technical efficiency. The results showed that the average production technical efficiency of apple growers in typical apple growing areas of Shaanxi and Shanxi was 0.513, which had a large room for improvement on the whole. After eliminating sample selection bias by using PSM method, adopting green production technology could significantly improve the technical efficiency of apple growers. According to the results, the corresponding policy suggestions were provided to promote the adoption of technology by apple growers, protect the health of soil, improve the production efficiency of apple growers and realize the green development of agriculture.
The Potential Role of Anomalous Geothermal Flux for Enhanced Basal Melting and Suppressed Ice Velocity at Haynes Glacier, West Antarctica
Authors: Bott Jason , Blankenship Don , Yan Shuai , Beem Lucas , Young Duncan
Published: March 2024

In NASA’s MEaSUREs Ice Velocity Data, a distinctive 8.5km diameter patch of slow-moving to stationary ice (0-15m/year) can be observed near the grounding line of Haynes Glacier, amidst much faster-flowing ice (300-1300 m/year). Additionally, a number of anomalously drawn-down englacial radar reflections are observed in multiple aerogeophysical surveys with the McCORDs (Multichannel Coherent Radar Depth Sounder) Instrument upstream of this ice velocity anomaly. The potential source of this velocity anomaly is hypothesized to be either anomalous geothermal flux or high frictional heat upstream, coupled to a thinning of the ice column as it nears the grounding line. These factors, taken together, imply a scenario where the warmer ice at the base of the ice column melts away while colder ice enters from above at the accumulation rate along the flowline. Upstream, with the ice column's relatively high thickness (~1000m), the basal ice experiences sufficient pressure to induce significant down draw of layers from substantial melting that is consistent with basal friction and/or a source of anomalous geothermal flux; the result is significant thermal advection of the much colder surface accumulation deep into the ice column. Downstream, where the ice thins, the  reduced pressure results in freezing of the anomalously cold ice to the bed, leading to the observed velocity anomaly.The testing of this hypothesis requires reconciling of the vertical velocity profile necessary to produce the down draw with either expected frictional melt or anomalous geothermal flux along the flowline (given the accumulation gradient). We present here this coupled thermal and kinematic modeling of Haynes Glacier from the site of the down draw to the sticky spot near the grounding line. With our models of temperature variations and ice flow characteristics within the Haynes Glacier system, we can further refine our understanding of the importance of heterogeneous geothermal flux for cryosphere evolution  - which may prove to be vitally important to fully understand fast-flowing and vulnerable ice streams in the Amundsen Embayment of West Antarctica. This, in turn, may have further implications for the study of heterogeneous heat flux and volcanic activity within the broader context of West Antarctica.
Maximum summer temperatures for the Western Tianshan Mountains of China inferred from tree rings over the past 300 years
Authors: Ren Meng , Liu Yu
Published: March 2024

    The trend of global climate warming is strengthening. During the 20th century, climate warming has increased more than it was at any other time in history, seriously affecting water security and food supply. With global climate warming, extreme temperature events have occurred continuously in many regions of the world and have seriously damaged the ecological environment and human health. In this context, it is crucial to strengthen the understanding of regional extreme temperatures, analyze their changing characteristics and understand their impact on global climate warming. As one of the regions most affected by climate warming, the Tianshan Mountains has suffered several ecological crises, including retreating glaciers and water deficits. The climate warming in the Tianshan Mountains is considered to be mostly caused by increases in minimum temperature and winter temperature, while the influence of the maximum temperature is unclear. Here, a 300-year tree-ring chronology developed from Western Tianshan Mountains, China was used to reconstruct the summer (June–August) maximum temperature (Tmax6-8) variations from 1718 to 2017. The reconstruction explained 53.1% of the variance in the observational records. Over the past 300 years, the Tmax6-8 reconstruction showed obvious interannual and decadal variabilities and experienced roughly six warm periods (1723–1732 AD, 1768–1785 AD, 1818–1834 AD, 1841–1898 AD, 1911–1929 AD and 1973–2012 AD) and five cold periods (1733–1767 AD, 1786–1817 AD, 1835–1840 AD, 1899–1910 AD, and 1930–1972 AD). Our reconstructed Tmax6-8 showed a significant warming trend (0.183℃/decade) after the 1950s, which was close to the increasing rates of the minimum temperature and mean temperature. We found that this significant warming of maximum temperature was also present in the whole Tianshan Mountains. The impact of the maximum temperature on climate warming has increased and cannot be ignored. Our reconstruction was found to be reliable and representative according to spatial correlation analysis. Additionally, the extremely cold years in the Tmax6-8 reconstruction were due to the cooling effect of strong volcanic eruptions. The reconstructed Tmax6-8 series was positively correlated with solar activity and negatively correlated with the summer North Atlantic Oscillation (SNAO) index. Combined with the periodic analysis, these results demonstrated that the Tmax6-8 variations in the Western Tianshan Mountains, China was influenced by volcanic eruptions at high frequency and synergistically influenced by solar activity at low frequency. This study revealed the significant influence of maximum temperature variability on global climate warming and clarified the climate mechanism, which will aid in future climate change prediction.
A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey
Authors: Chen Bo Rui , Chao Wei An
Published: March 2024

The water level and discharge of river are crucial parameters to understand the variance in riverbed scour. The detail behavior of scouring can be studied by the hydraulic simulation. The grain-size distribution of riverbed is also one of crucial parameter for modeling. Thus, how to investigate the grain-size of riverbed efficiently and swiftly is the urgent issue. However, the conventional measurement methods including Wolman counts (particles sampled at a fixed interval) which are a long and laborious task cannot survey the grain-size efficiently in the large area. In recent years, with an advantage of image segmentation and recognition has been applied to the investigation of grain-size, for example, capturing images through UAV and generating orthoimage is one of commonly used image technique. Although above the method can investigate the grain-size in the large area, it does not provide the information in the field immediately. Hence, a recent study developed the low-cost portable scanner to obtain the information of grain-size distribution in the field. However, the calibrating parameters of camera (e.g., height camera capture) are necessary before survey, and the uncertainties in calculation of image resolution will significantly affect the accuracy of grain-size analysis. Therefore, this study provides the additional algorithm to analyze the grain-size by using RGB-D image as inputs. The application of RGB-D can be categorized into two-dimensional (2D) and three-dimensional (3D) spaces. In a case of 2D, it integrates depth information with traditional RGB image processing to separate the grain-size of riverbed from the background (e.g., bottomland). Furthermore, depth information is also applied for grain-size edge detection. In a case of 3D, the collected RGB-D image information is transformed into point cloud data, then extract 3D features of grain particle by Deep learning, specifically PointNet. Our study demonstrates that clustering of 3D features can achieve the automatic identification of particle. The grain-size of particle can also be estimated by fitting 3D ellipsoid geometry. In the end, results show the grain-size distribution curves with the RGB、RGB-D、PointNet recognition, and compare with the true observations. 3D image information provides the cloud points of grain object, leading the possibility of estimating the 3D geometric morphology of the object. Our study successfully overcomes the limitations of conventional RGB-based process, which could only capture size and shape information in 2D planar. RGB-D-based image recognition, is an innovative technique for the hydraulic problem, not only advances survey efficiency but also addresses the intricate steps required for field investigations. Key words: Riverbed grain size, RGB-D image, Point cloud, Deep Learning
Extending the Decision-Making Lead time of Municipal Water System Management Using Teleconnections to Support Supply and Demand Estimates
Authors: Burian Steve , Johnson Ryan , Aziz Danyal , Strong Courtenay , Brooks Paul , Wolf Margaret , Jamison Logan , Stone Luke , Briefer Laura , Stewart Jesse , Kirkham Tracie , Prue Tamara
Published: March 2024

Western United States municipal water system management requires estimates of system performance with sufficient lead time to identify and mitigate potential vulnerabilities. Given their dependence on winter snowpack and the resulting timing of surface water availability contrasting that of peak water demand, there is a need to deliver earlier estimates of system performance to increase the lead time for decision-making. Addressing this need, we develop a long to short-term water systems operations workflow that provides operators with estimates of performance with up to a ten-month lead time and demonstrate the workflow using the Salt Lake City Department of Public Utilities in Northern Utah, United States. The workflow leverages teleconnections with global climate signals to estimate the precipitation, surface water yield, and demand for up to a ten-month forecast horizon. We use the estimates of supply and demand to drive a water systems model that provides a range of likely reservoir levels, groundwater withdrawal volumes, and volume of out-of-district water needs to determine potential system vulnerabilities needed to evaluate and develop mitigation measures.
Sedimentary Evolution of the Paleocene–Eocene Carbonate Platform in the Offshore Indus Basin: Implications for Hydrocarbon Exploration
Authors: Liang Jie , Li Sen , Liao Jing , Gong Jianming , Chen Jianwen
Published: March 2024

The offshore Indus Basin, situated at the convergence of three major tectonic plates in the eastern sea area of Pakistan, has undergone complex tectonic-sedimentary evolution processes throughout geological history. During the Paleocene–Eocene period, the basin was equatorially positioned, hosting a large-scale carbonate platform whose sedimentary characteristics and evolution remain unclear due to limitations in well drilling, as well as the quality and quantity of seismic data. This knowledge gap hinders in-depth oil and gas exploration. This study employs a combination of existing and newly acquired two-dimensional seismic data, along with well-to-seismic calibration, to identify seismic facies of the Paleocene–Eocene carbonate platform in the offshore Indus Basin. The internal plane and vertical distribution characteristics in different periods were depicted, and the sedimentary evolution history and the main controlling factors were analyzed. Six types of seismic facies were identified, with the mound or lenticular shape-medium weak amplitude-medium low continuous-medium low frequency seismic reflections corresponds to reef facies exhibiting favorable reservoir petrophysical properties. The carbonate platform in the study area is categorized into four sedimentary evolution stages: initial development, prosperity, recession, and inundation. The study correlates these stages with changing platform characteristics such as vertical growth, increased thickness of reef shoal facies, platform edge recession, and final inundation by seawater. Considering regional tectonic evolution, sea-level fluctuations, paleoclimate evolution, and the temporal and spatial distribution characteristics of the carbonate platform, the study suggests that a pre-existing ancient highland terrain shaped by magma intrusion limited spatial distribution, shape, and scale of the carbonate platform during the Paleocene–Eocene period. Sea-level changes and paleoclimate evolution influenced the platform shape. In the hydrocarbon accumulation process of the reef reservoir, the distribution of effective source rocks, migration pathways, and the spatial arrangement of reef reservoirs emerged as key control factors. The study identifies an isolated platform in central area lacking sufficient oil and gas filling, confirmed by drilling. Conversely, the southern area features numerous reefs with various scales, connected by northeast-trending faults serving as effective channels for hydrocarbon migration. This study provides essential insights into regional sea-level changes, driving mechanisms, and supports hydrocarbon exploration in the offshore Indus Basin.
Localising Signatures of Particle Acceleration During Solar Flare in Low Solar Atmosphere Using Combined EUV, X-ray and Radio Observations
Authors: Bhunia Shilpi , Hayes Laura , Klein Karl Ludwig , Gallgaher Peter T. , Maloney Shane , Vilmer Nicole
Published: March 2024

It is well known that flare-accelerated electrons can produce hard X-ray (HXR) emission and Type-III radio bursts. The HXR emission is produced by the accelerated electrons propagating towards the chromosphere where they deposit their energy. In contrast, Type-III radio bursts are produced by the accelerated electron beams traveling toward the outer solar atmosphere. Hence a temporal correlation between these two kinds of emission may imply a common origin of the accelerated electrons providing insight into the acceleration process, and allowing us to connect electrons at the Sun to those in the heliosphere On 2022-Nov-11 11:30 - 12:00 UT, the Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter observed a highly energetic flare event with an excellent time resolution of 0.5 s. Simultaneously there were observations of multiple coronal and interplanetary Type-III radio bursts from several instruments such as WIND/WAVES, I-LOFAR, and ORFEES spanning the frequency range from 1 - 1000 MHz.We find an excellent temporal correlation between the X-ray and radio time series. We do multiwavelength imaging analysis using AIA, STIX, and NRH to locate the acceleration origin and track the electron beams during the eruption.
Co-seismic ionospheric total electron content disturbances of Turkey earthquake doublet in 2023 detected by Beidou geostationary satellites
Authors: Rao Huan , Chen Chieh-Hung
Published: March 2024

The M7.8 and M7.5 earthquakes that occurred on 6 February 2023 in Turkey caused co-seismic ionospheric disturbances, and ionospheric total electron content (TEC) disturbances can be detected by Beidou geostationary satellites. The 17 GNSS continuous observation stations from IGS Net around the epicenters receive electromagnetic wave signals emitted by two Beidou geostationary satellites located above the equator at a frequency of 1 Hz. That allows us to obtain the TEC time series at fixed ionospheric piercing points (IPPs). Disturbances triggered by the M7.5 earthquake propagate farther and have a larger amplitude in general traveling at least 1600 km northwest and 800 km south and reaching the furthest area of the study with the maximum amplitude of about 2.5 TECU. For Mw 7.8 earthquake, the disturbances can be observed about 800 km northwest of the epicenter while no significant disturbances detected further away and the maximum amplitude of the disturbances is about 0.25 TECU. The TEC disturbances propagation speeds corresponding to the M7.5 and M7.8 earthquakes are 2.77 km/s and 2.60 km/s as the results of least squares fitting performed on epicentral distances and travelling times of the disturbances with the greatest amplitude. The speeds are closer to Rayleigh waves velocity of about 3 km/s at the surface rather than acoustic waves velocity of about 1 km/s in the ionosphere. The velocity of propagation for the co-seismic ionospheric disturbances, as determined by utilizing the Beidou geostationary satellites during two earthquakes, is consistent with that of the Rayleigh waves determined from the seismometers. Meanwhile, the velocity exhibits directional disparities for M7.5 earthquake.
Physical property characterization of sand ridge sediments in the continental shelf of the South Sea, Korea
Authors: Kim Gil Young , Park Kiju , Hong Seok-Hwi , Jeong Eun Je , Lee Gwang Soo , Yoo Dong Geun , Kong Gee Soo , Yu Shin
Published: March 2024

Sand ridges are more developed around the continental shelfs with the strong tide current. Various sand ridges are distributed in the continental shelf of the South Sea, Korea. The deep core samples from the sand ridges of South Sea were collected and analyzed to characterize physical property with sedimentary depth. Laboratory analysis (compressional velocity, physical properties, and grain size) was conducted on core samples. Wet bulk densities are mostly ranges from 1.75 to 2.15 g/cm3. Grain densities are dominant between 2.55 g/cm3 and 2.65 g/cm3. Velocities are distributed between 1650 m/s and 1850 m/s. Whereas, porosities are low less than 50% (mostly 40%) compared to muddy sediments. The sand ridge sediments are mostly composed of sandy materials (less than 4Ø in mean grain size). Shell fragments and are intermittently included in the sediments. Muddy sediments are also frequently observed. The lithology of deep core samples with sedimentary depth are various, reflecting changes of sedimentary environments during deposition. The physical property data were readily classified in good agreement with the lithological units alternating sand and muddy sand with sedimentary depth. The sand ridge sediments in study area were largely originated and redistributed from paleo-Seomjin River, caused by sea-level changes during the Quaternary. These results suggest that the physical properties of these sediments are mainly controlled by depositional processes in the vicinity of the paleo-Seomjin River, and that sea-level change specifically was a dominant sedimentary process in the study area during the Quaternary.
An update on the perturbations in stratospheric composition and climate following the Hunga Tonga-Hunga Ha'apai volcanic eruption
Authors: Wang Xinyue , Randel William , Yu Wandi , Zhu Yunqian , Zhang Jun
Published: March 2024

The Hunga Tonga-Hunga Ha'apai (HTHH) volcanic eruption on January 15th 2022 injected unprecedented amounts of H2O as well as modest amounts of aerosol precursor sulfur dioxide into the stratosphere. Satellite observations have shown strong stratospheric cooling and circulation changes throughout 2022. Large ozone reduction in the Southern Hemisphere wintertime midlatitudes and springtime Antarctic ozone losses are also observed. In addition, a chemistry-climate model (WACCM) can track the evolving HTHH plumes and capture observed responses to the volcanic eruption till the end of 2023. We will present a comprehensive update regarding the perturbations in stratospheric composition and their effects on large-scale circulation since the HTHH eruption. We will also examine the longer-term evolution of HTHH H2O burden and will quantify the contributions of polar dehydration, stratosphere-troposphere exchange of mass, and chemical process.
Improved interrill erosion prediction by considering the impact of the near-surface 
Authors: Wang Bin , Wang Yujie , Wang Chenfeng
Published: March 2024

The mechanism of the interrill erosion process is still unclear under complex conditions. Spatio-temporal variations of the near-surface hydraulic gradient are a common occurrence; however, few attempts have been made to characterize the near-surface hydraulic gradient for erosion prediction. Therefore, the objective of this study is to determine the influence of exogenic erosional forces (rainfall, overland flow, and seepage) on interrill erosion processes by considering the impact of the near-surface hydraulic gradient. Five near-surface hydraulic gradients (70% of field capacity, field capacity, saturated, artesian seepage at 20 cm and 40 cm of the hydrostatic pressure head) were applied in clay loam soil at two representative slope gradients of 8.75% and 17.63% under three rainfall intensities of 30, 60, and 90 mm h-1. The results showed that the near-surface hydraulic gradient was the dominant factor in the interrill erosion process in addition to rainfall intensity (I), runoff (Q), and slope gradient (S). There was a significant improvement in the prediction accuracy of the interrill erosion rate when the factor of near-surface hydraulic gradient was introduced into the interrill erosion prediction equation based on the Water Erosion Prediction Project (WEPP) concept. The R2 and NSE values were 22.36% to 210.00% higher than those of existing empirical equations (main parameters: I, I&S, I&Q, I&S&Q). The correlation matrix results indicated that the flow velocity was a key hydraulic parameter for predicting the interrill erosion rate. The interrill erosion rate was predicted well by a simple power function of the flow velocity, although this relationship lacks clear physical meaning. We also found that the interrill erosion rate increased as a power function with the runoff depth, rainfall intensity, hydrostatic pressure head and slope gradient. Considering the integrated effect of the exogenic erosional dynamics on the interrill erosion, a power function that included the physical description of the hydrodynamic parameters, rainfall intensity and hydrostatic pressure head was used to predict the interrill erosion rate. The results of this research provide new insights into developing process-based and mechanistic models for interrill erosion processes.
Simulating Mass Balance and Dynamics of Mountain Glaciers within an Earth System Modeling Framework
Authors: Minallah Samar , Lipscomb William , Swenson Sean , Leguy Gunter
Published: March 2024

Simulating mass changes and ice dynamics for mountain glaciers using Earth System Models (ESMs) is challenging due to their small size, sheer number, and spatial discontinuities in the ground ice coverage. This has resulted in a knowledge and representational gap in ESMs. However, there is a need for scaling ESMs from global to regional domains for comprehensive glacio-hydrological and hydroclimatic assessments.We introduce new developments for simulating the mass balance and dynamic evolution of mountain glaciers within the Community Earth System Model (CESM). We provide an overview of this work across two spatiotemporal scales related to: (1) the dynamic evolution of the Central European glaciers under the GlacierMIP3 protocol using the Community Ice Sheet Model (CISM) and (2) the energy and water balance of the Upper Indus glaciated basins at daily-monthly timescales using the Hillslope Hydrology configuration of the Community Land Model (CLM).
Wet atmospheric depositional fluxes of organic carbon: Global Dynamics of Fossil Derived Brown Carbon
Authors: Lee Min-Young , Kim Tae-Hoon
Published: March 2024

To estimate the annual wet depositional fluxes of dissolved organic carbon (DOC) and particulate organic carbon (POC) and the global wet depositional flux of Brown Carbon (BrC) from fossil-fuel derived, we conducted an analysis of BrC in rainwater samples collected throughout 2018, from January to December in Jeju, volcanic island of Korea.. We calculated the annual wet depositional fluxes of DOC and POC in Jeju to be 0.7 g C m-2 yr-1 and 0.4 g C m-2 yr-1, respectively. Notably, the global magnitude of BrC from fossil fuels deposited through wet processes was estimated to be around 2.0±0.6 Tg C yr-1, based on the ratio of humic-like substances to OC fluxes. The contribution of organic carbon (OC) from these deposits to the ocean is approximately 53 ± 35% of the total global wet depositional OC flux. The flux of BrC derived from fossil fuels is comparable to about 1.6% of the total wet deposited OC in the world's oceans. Therefore, our results suggest that current estimates might significantly underrepresent the global organic carbon pool in coastal oceans, given the more resistant nature of the majority of fossil-fuel-derived organic carbon.
Spatial coherence as a key metric for interpreting marine records of Holocene temperature variability
Authors: Cleveland Stout Rebecca , Proistosescu Cristian , Roe Gerard
Published: March 2024

Constraining forced and unforced climate variability impacts interpretations of past climate variations and predictions of future warming. However, comparing general circulation models (GCMs) and Holocene hydroclimate proxies reveals significant mismatches between simulated and reconstructed low-frequency variability on multi-decadal to multi-centennial timescales. Using a combination of GCMs and energy balance models, we have previously identified robust differences in the spatial pattern and magnitude of forced and unforced temperature variability on these long timescales. Our work suggests that not only is it important to understand variance, but also the spatial correlation between temperature at different sites. In principle, the spatial correlation at low frequencies is strongly related to the nature of variability. Now, we apply this dynamical understanding to the proxy record—specifically, across 49 globally-distributed Holocene sediment core sites with Mg/Ca and Uk37-based temperature reconstructions. We identify spatiotemporal statistics of forced and unforced variability using GCMs, and then use proxy-system models to assess how variability and spatial correlation are filtered by Mg/Ca and Uk37. Understanding these spatial correlations provides extra targets for interpreting these cores. Ultimately, we seek to characterize the forced and unforced components of slow modes of climate adjustment across the Holocene. 
Unfolding Multivariate Drought Risk in Large River Basins accounting Onset Seasonality and Event Magnitude
Authors: Raut Aparna , Ganguli Poulomi
Published: March 2024

The frequency and severity of droughts are expected to increase in the warming climate. Understanding mutually interacting drought properties, such as their severity (deficit volume) and time to onset, is crucial for managing reservoir operations and low flows. Previous studies have performed bivariate drought frequency analysis considering drought severity and duration across different climate regions. However, little is known about the role of drought seasonality in shaping drought severity. This study aims to investigate the dependence between onset time (i.e., directional occurrence date) and deficit volume and evaluate the impact of drought seasonality on the deficit volume distributions in disparate climate regions across the global tropics. Leveraging streamflow observations from representative catchments in the northern and southern hemispheres and considering the nonlinear dependence strengths between onset time and deficit volume, we implemented a multivariate drought frequency model that yields a conditional probability of drought severity given the timing of peak drought intensity. We consider multiple univariate probability functions for modelling drought deficit volume, whereas drought onset time is modelled using von Mises distribution. Further, the joint dependence between drought onset and deficit volume is modeled using a bivariate Archimedean class of copulas. First, we show temporal variations of exceedance probabilities of drought deficit volume and their seasonal clustering behavior during dry/wet phases and then explore any possible shift in the risk of peak drought intensity based on its seasonality. Finally, employing a flexible multivariate probabilistic tool, we demonstrate different scenarios of drought characteristics combinations and a seasonality-informed drought probability model, aiding understanding complex processes of drought propagations across disparate climate regimes and assessing possible climatic shifts to drought frequency.
Sediment remobilization over subaqueous sand waves: Insights from in-situ observation in the northern South China Sea
Authors: Zhao Yulong , Zhang Yanwei , Ma Pengfei , Zhang Xiaodong , Liu Zhifei
Published: March 2024

Subaqueous sand waves are widely observed in the world′s oceans, but few in-situ observations have been performed to understand the dynamic processes of how they form and migrate. Large-amplitude subaqueous sand waves, 1.5 to 20 m in height and 55 to 510 m in length, are found on upper continental slope of the northern South China Sea, at water depths of ~ 150 to 800 m. Herein, high-resolution tripod observations were conducted in this sandwave field to understand the dynamic mechanism how sandy sediments are remobilized by oceanic dynamic processes, in particular internal solitary waves and internal tides. Our results indicate that near-critical reflection of diurnal internal tides at the continental slope can cause high suspended sediment concentration within the bottom water at a narrow belt further upslope to the observation site downslope locations. These sediments are transported downslope by the ebb tides to the observation site, forming the daily-recurring high suspended sediment concentration. The passage of episodic extreme internal solitary waves can result in much denser high sediment clouds with a thickness of up to ~ 40–50 m above the seafloor. These high suspended sediment concentration events are caused by in-situ resuspension of sediments from the seabed and upward transport of these sediments out of the boundary layer in response to passing of internal solitary waves. The two sub-processes of sediment resuspension are regulated by distinct dynamic mechanisms: incipient sediment resuspension from seafloor is controlled by current-induced strong bed shear stress, while the upward transport of sediments out of the bottom boundary layer is driven by the upwelling convergent currents at the rear of the internal solitary waves. Such results provide new insights into understanding the dynamic mechanism of the so-called ‘resuspension’ process in marine sedimentology. Our results also highlight the importance of internal solitary waves and internal tides in modulating sediment remobilization over subaqueous sandwave fields.
Tracking the jets as Lagrangian objects
Authors: Rivoire Louis , Curbelo Jezabel
Published: March 2024

Various algorithms developed to track the synoptic evolution of the subtropical jets have proved useful in diagnosing variability and trends. However, consensus about trends remains low, and issues in jet detection persist. Notably, algorithms:Frequently employ a variety of climatological parameters, making them unsuitable for long-trend analyses;
Rely on instantaneous meteorological fields (or Eulerian-averaged fields), thereby overlooking the temporal coherence of jet features. This results in the inability to systematically separate the true axis of the jets from underlying waves, affecting the characterization of variability known to affect the mean position of the jets —and long-term trends.
To address these limitations, we define the jets as Lagrangian Coherent Structures; persistent features that resist synoptic variability and thereby shape the atmospheric circulation. Using this Lagrangian definition, a new algorithm named JetLag is developed and applied to the ERA5 reanalysis. JetLag employs 2 parameters –a time scale and a spatial scale, both set by the Rossby wave dispersion relation– and is virtually insensitive to changes in those parameters, within physical bounds. Compared to wind-based methods, we show that JetLag:Locates jet features with better temporal coherence;
Has enhanced capabilities for detecting weak and highly variable jets;
Produces a different seasonal cycle of mean jet position;
Produces different decadal to multi-decadal variability, with implications for trend detection.
We also present a new jet axis dataset for use by the community.
Eddy covariance measurements of air-sea heat and momentum fluxes under tropical cyclones and hurricanes in the northwest Tropical Atlantic
Authors: Zhang Dongxiao , Foltz Gregory , Zhang Chidong , Fairall Chris , Zhang Jun , Kim Hyun-Sook , Mehra Avichal , Chiodi Andrew , Cronin Meghan , Thompson Elizabeth , Thomson Jim , Looney Lev , Chi Nan-Hsun , Schulz Hauke , Savarin Ajda , Mazza Edoardo
Published: March 2024

Tropical cyclones (TCs) and hurricanes are among the strongest Mesoscale Convection Systems originating from the tropical oceans and can cause significant loss of lives and properties when landing. Prediction of TCs, especially their rapid intensification, remains challenging for numerical forecasts. Theoretical and modeling studies have shown that the surface turbulence heat flux fuels hurricane intensification, while the momentum flux or wind stress transfers the kinetic energy from the storm to the ocean to regulate the ocean mixing and stratification which in turn affect the Sea Surface Temperature and heat flux. The balance between the surface enthalpy flux (sum of sensible and latent heat flux) and drag plays a critical role in the TC and hurricane intensification. Due to the lack of direct observations inside the TCs and hurricanes, studies largely based on numerical models, lab experiments, air-deployed dropsondes, and indirectly from momentum budget analysis, have suggested a large deviation of wind stress and drag coefficients at high wind speed of > 20 m/s in TC and hurricane conditions. During the 2021-2023 hurricane seasons, a fleet of 5-12 Saildrone Uncrewed Surface Vehicles (USVs) have been deployed each year to intercept the TCs and hurricanes to make direct observations of the extreme air-sea interaction process. They provided real-time 1-minute averages of near-surface meteorology and ocean variables (5-minute for ocean currents) to hurricane forecast centers. This study utilizes the high-resolution 20-Hz data made available once the Saildrone USVs returned from their cruises after the hurricane season to investigate direct eddy covariance (EC) measurements of wind stress for a better understanding of the drag coefficients under TC and hurricanes. The directly observed drag coefficient, as well as the EC heat transfer coefficient (for sensible heat flux), will be compared to those used in the bulk flux algorithm (COARE) and in forecast models. Particular attention will be paid to the variations in different wind and wave conditions within the mesoscale system.
The State of Global Air Initiative: Increasing Access to Data on Air Quality and its Health Impacts 
Authors: Sekar Abinaya , Wright Ada , Nthusi Victor , Pant Pallavi
Published: March 2024

Air pollution is the leading environmental risk factor for human health, with millions of deaths annually and significant societal and economic costs. While access to the latest, reliable, and free air quality and health data is vital for informed decision-making, data on air pollution remains limited, especially in low- and middle-income countries (LMICs). The State of Global Air Initiative (SoGA), a collaboration between the Health Effects Institute and the Institute for Health Metrics and Evaluation, addresses this need by presenting comparable data on levels and trends of air quality and the associated health impacts for more than 200 countries and territories and more than 7000 cities around the world.The data are drawn from the Global Burden of Disease (GBD) Study and include data on exposure to air pollutants - fine particulate matter (PM2.5), ozone (O3) and nitrogen dioxide (NO2) and the associated burden of disease – deaths, death rate and disability adjusted life years (DALYs) as well percentage of deaths attributed to specific causes of disease and death. To enhance accessibility and reach, the information is presented in a variety of ways including reports, factsheets, an interactive data app, story maps, and videos, often in multiple languages. All the reports and data resources are accessible via https://www.stateofglobalair.org/.These estimates are produced using a variety of data - air quality estimates are produced from a combination of data from over 10,000 ground-based monitors, satellite observations, and outputs from GEOS-Chem, a chemical transport model. The disease burden estimates are produced using country-specific death and morbidity rates, other health data including disease incidence, population demographics, and exposure-response curves derived from epidemiological studies. However, since the estimates rely on available data on air quality and health, in some cases, estimates are uncertain, particularly in parts of Asia and Africa where data gaps remain. A new dataset featuring estimates for the year 2021 is set to be released shortly. Despite the caveats, such information can be used for public engagement and for making evidence-based decisions to improve air quality and public health.In 2022 alone, the SoGA initiative reached audiences in more than 50 countries, and for many countries, they are the only available estimates for air pollution levels and associated health impacts. The data have been used for public engagement, media reporting and to inform policy decisions, especially in LMICs. These data are also relevant for scientific research.Overall, the SoGA initiative serves to close the gap between scientific research and public understanding on air pollution and its health impacts. In this presentation, we will showcase data from the SoGA platform, review lessons learnt and highlight opportunities for future research and engagement.
Advancing Forecast Precision: Data-Driven Model Generation via Data Assimilation
Authors: Goodliff Michael , Miyoshi Takemasa
Published: March 2024

Data-driven models (DDMs) are mathematical or computational models built upon data, where patterns, relationships, or predictions are derived directly from the available information rather than through explicit instructions or rules defined by humans. These models are constructed by analysing large volumes of data to identify patterns, correlations, and trends. In areas such as numerical weather predictions (NWP), these DDMs are becoming increasingly popular with an aim to replace numerical models (or components of) based on real observations. Data assimilation (DA) is a process which combines observations from various sources with numerical models to improve the accuracy of predictions or simulations of a system's behaviour.
This presentation focuses on the application of DA methodologies in enhancing the precision and efficiency of DDM generation within computation models characterised by inherent observation error. The aim is to demonstrate the pivotal role that DA techniques can play in refining and optimising the process of DDM generation, thereby augmenting the accuracy and reliability of predictive models despite the presence of observational uncertainties.
Revealing cyanosphere microbial diversity of terrestrial cyanobacteria
Authors: Pietrasiak Nicole , Palmer Brianne , Couradeau Estelle , Stajich Jason
Published: March 2024

The cyanosphere contains heterotrophic microorganisms living within the exopolysaccharide sheath of cyanobacteria and serves as an interface between the cyanobacteria and their surrounding ecosystem. The symbiosis between the cyanobacterial host and its cyanosphere microbes spans the mutualistic-antagonistic spectrum. Understanding these relationships will predict the success of terrestrial cyanobacteria and the ecosystem services they provide including primary production in often oligotrophic environments. However, our understanding of the microbial diversity within the cyanosphere is limited. In this study, we used metagenomic sequencing to construct 528 metagenome-assembled genomes (MAGs) from the cyanosphere microbes associated with 50 unialgal terrestrial Cyanobacteria cultures, spanning 12 orders. We found that the composition of cyanosphere microbial communities was unique between Cyanobacteria hosts and was largely influenced by environmental (habitat, precipitation, and temperature) and phylogenetic variables (host order). Alphaproteobacteria was the most common cyanosphere microbial class and Bosea, Devosia, Hyphomicrobium, Mesorhizobium, and Sphingomonas were core genera found across all habitats. Interestingly, the nitrogen-fixing cyanobacterial order, Nostocales, contained the highest diversity of cyanosphere bacteria, many of which have the genomic potential also to fix atmospheric nitrogen. Given the observed variations in the cyanosphere microbial communities across different hosts, future considerations for ecological assessments and cyanobacterial restoration efforts must extend beyond the cyanobacteria to encompass their associated microbial communities.