bluuebunny/crossref_metadata_2025 huggingface dataset:
Lunar secondary crater distributions and ejecta fragment size velocity distributions: implications for regolith redistribution
Authors: Singer Kelsi , Skjetne Helle , Stopar Julie , Huffman Mikayla , Chapman Clark , Ostrach Lillian , Jolliff Brad , McKinnon William
Published: February 2023

We have performed an extensive study of secondary craters associated with specific primary craters on the Moon.  These data can be used to understand aspects of both (1) the secondary craters themselves and (2) the ejecta fragments that formed them.  Studying ejecta and secondary craters are a part of understanding the overall contributions of impacts to shaping and redistributing material across the lunar surface. We produced secondary crater size-range distributions for a large range of primary crater sizes (~0.8-660 km dimeter primaries).  Our results can be used to make a map of estimated maximum secondary crater sizes across the Moon.  They can also be used to test if a specific secondary crater cluster is likely related to a given primary crater.   We also produced ejecta fragment size-velocity distributions for all our study sites.  These results can be used to understand the size and velocity of the ejecta fragments that were ejected as part of the primary impact.  This helps us understand the dynamics of the primary impact and the formation of fragments (or clusters of fragments) and how they are ejected during the passage of the shock wave through a planetary surface.  This new empirical data can be used to help constrain analytical and numerical models of dynamic fragmentation, place constraints on the largest ejecta fragments expected be ejected at escape velocity from the Moon, and used as inputs into models of regolith development and impact gardening. We will present the most current results on the above topics.  Initial results for 6 primary craters are presented in Singer et al. 2020 where we discovered a previously unrecognized trend where the size velocity distributions are dependent on the size of the impact (i.e., scale dependent).  We now have data on 10 additional primaries and further applications of the study. Singer, K. N., Jolliff, B. L., & McKinnon, W. B. (2020). Lunar secondary craters and estimated ejecta block sizes reveal a scale-dependent fragmentation trend. J. Geophys. Res., 125(8), e2019JE006313. doi:10.1029/2019JE006313
Artificial Intelligence Models for Detecting Spatiotemporal Crop Water Stress in schedule Irrigation: A review
Authors: Koohi Elham , Gumiere Silvio Jose , Bonakdari Hossein
Published: February 2023

Water used in agricultural crops can be managed by irrigation scheduling based on plant water stress thresholds. Automated irrigation scheduling limits crop physiological damage and yield reduction. Knowledge of crop water stress monitoring approaches can be effective in optimizing the use of agricultural water. Understanding the physiological mechanisms of crop responding and adapting to water deficit ensures sustainable agricultural management and food supply. This aim could be achieved by analyzing stomatal conductance, growth rate, leaf water potential, and stem water potential. Calculating thresholds of soil matric potential, and available water content improves the precision of irrigation management by preventing water limitations between irrigations. Crop monitoring and irrigation management make informed decisions using geospatial technologies, the internet of things, big data analysis, and artificial intelligence. Remote sensing (RS) could be applied whenever in situ data are not available. High-resolution crop mapping extracts information through index-based methods fed by the multitemporal and multi-sensor data used in detection and classification. Precision Agriculture (PA) means applying farm inputs at the right amount, at the right time, and in the right place. RS in PA captures images in different spatial, and spectral resolutions through in-field, satellites, aerial, and handheld or tractor-mounted such as unmanned aerial vehicles (UAVs) sensors. RS sensors receive the electromagnetic signals of plant responses in different spectral domains. Optical satellite data, including narrow-band multispectral remote sensing techniques and thermal imagery, is used for water stress detection. To process and analysis RS data, cloud storage and computing platforms simplify the complex mathematical of incorporating various datasets for irrigation scheduling. Machine learning (ML) algorithms construct models for the regression and classification of multivariate and non-linear crop mapping. The web-based software gathered from all different datasets makes a reliable product to reinforce farmers’ ability to make appropriate decisions in irrigating agricultural crops.Keywords: Agricultural crops; Crop water stress detection; Irrigation scheduling; Precision agriculture; Remote Sensing.
Sensitivity of African Easterly Waves to Dust Direct Radiative Forcing
Authors: Bangalath Hamza Kunhu , Raj Jerry , Stenchikov Georgiy
Published: February 2023

African Easterly Waves (AEWs) are the most important precipitation-producing dynamic systems in tropical Africa and Atlantic, where dust in the atmosphere is abundant. But the past studies lack consensus on the sign and magnitude of the dust radiative forcing impact on AEWs primarily because of the disagreement in calculating dust solar radiation absorption. The incapability of coarse-resolution models to represent various dust-AEW interactions is another source of uncertainty. The present study uses a high-resolution atmospheric general circulation model, HiRAM, to investigate the sensitivity of AEWs to the dust direct radiative forcing when dust shortwave absorption varies within the observed limits. Global simulations are conducted with the 25 km grid spacing to adequately simulate AEWs and associated circulation features. Four 10-year experiments are conducted: One control experiment without dust and three others with dust assuming dust is an inefficient, standard, and very efficient shortwave absorber. The results show that AEWs are highly sensitive to dust shortwave absorption. As dust shortwave absorption increases, AEW activity intensifies and broadens the wave track shifting it southward. The 6-9 day waves are more sensitive to dust shortwave absorption than the 3-5 day waves, where the response in the former has a stark land-sea contrast. The sensitivity of AEW to dust solar radiation absorption arises from a combination of energy conversion mechanisms. Although baroclinic energy conversion dominates the energy cycle, the responses to dust shortwave heating in barotropic and generation terms are comparable to that in baroclinic conversion. 
Molards as proxies of mountain permafrost degradation: direct comparison of experimental studies and field observations
Authors: Beck Calvin , Font Marianne , Conway Susan , Philippe Meven , Magnarini Giulia , Morino Costanza
Published: February 2023

Mountain permafrost is increasingly retreating due to climate change. This retreat leads to positive climatic feedback loops and poses safety risks due to more frequent slope instabilities. Therefore, assessing the condition and evolution of permafrost is critical. However, mapping the extent and retreat of permafrost is not as straightforward as for other elements of the cryosphere because permafrost cannot be directly mapped by remote sensing. In some mountain landslides there are cones of loose debris, which are remnants of formerly ice-cemented blocks. These cones are called “molards” and they indicate the presence of an area of discontinuous permafrost at the level of the detachment zone. The initial ice-cemented blocks range in height from 50 cm to 15 meters. The goal of this project is to use molards as proxies of mountain permafrost degradation. Therefore, we have to understand the physical processes leading to the formation of molards as well as how these processes determine the final molard shape. To achieve this goal we recreate molards by using physical modeling and we have investigated molards at several Icelandic field sites. For the physical modeling it is necessary to downscale the molards to an initial cube size of ~30 cm due to current laboratory limitations. The initial blocks are created by freezing fully water saturated sediment in a wooden mold at -20°C for 48 hours. Sediment from actual Icelandic molards is used as well as other reduced complexity simulants with different grain sizes, grain shapes, and clay content.We let the blocks degrade for 72 hours under a controlled and monitored laboratory environment with constant temperature and humidity conditions. We use a photogrammetric time-lapse system to create a digital elevation model of the degrading block to detect changes in hourly time-steps. Our initial results show that increasing clay content strongly influences the degradation speed and the final molard shape because it increases cohesion. In the field we have identified conical and trapezoidal cross-sections as the predominant shape for molards. But in the laboratory setting, high clay content means that the blocks do not degrade into this characteristic shape (without further meteorological influence). In this case,  landslide-like processes and single rockfall events dominate the molard formation process. For coarser grain sizes and low clay contents, rockfall is the dominant process, and both the conical and trapezoidal cross-sections can be reproduced in the experiments.
Effect of the Coastal Large-Scale Environment on the Tropical Diurnal Cycle
Authors: Maloney Eric , Natoli Michael , Riley Dellaripa Emily , Bui Hien , DeMott Charlotte , Short Ewan
Published: February 2023

Environmental conditions supporting offshore propagation of diurnal precipitation near tropical coastlines are examined. In particular, the effect of the near-coastal background wind, moisture, and surface wind speed and fluxes on offshore precipitation propagation is assessed for the Philippines, northern Australia, and Panama Bight region near Colombia. Reanalysis fields, satellite precipitation, surface wind speed (from the CYGNSS satellite), and flux observations, and the Cloud Model 1 (CM1) are used in this work. In general, a moist offshore environment and enhanced wind-driven surface fluxes support offshore propagation of strong diurnal convective disturbances. Near the west coast of Luzon, a weak offshore wind in the lower free troposphere also supports offshore propagation, as often occurs in the transition phases of the boreal summer intraseasonal oscillation from suppressed to enhanced daily mean convection. Vertically-integrated moist static energy budget analysis is used to support these results. Sensitivity tests with the CM1 verify the importance of weak offshore flow and a moist offshore environment for supporting offshore propagation of diurnal precipitation.
Formation of Transient Foreshock Structures Upstream of Mars and Earth: A Comparative Study
Authors: Madanian Hadi
Published: February 2023

In the foreshock region of planetary and terrestrial bow shocks, interaction of reflected solar wind ions with the incident solar wind and the interplanetary magnetic field gives rise to a variety of transient plasma structures and instabilities, and the ion dynamics and ion kinetic scale processes drive the foreshock environment. In this comparative study, we consider specific examples of transient foreshock structures upstream of Mars and Earth and contrast differences between theri formation process, contributing ion populations, and source region of ion populations. Due to the smaller size of Mars and its bow shock compared to Earth and with respect to upstream ion convective gyroradius, reflected ions with hybrid trajectories that straddle between the quasi-perpendicular and quasi-parallel bow shocks can contribute to formation of foreshock transients. The size of transient foreshock structures upstream of Mars differs compared to Earth, which influences their propagation and impact through the magnetosheath and lower plasma boundaries.
On the Entrainment of Glacial Meltwater by the Gulf Stream
Authors: Marchal Olivier , Condron Alan
Published: February 2023

The fate of glacial meltwater introduced into the ocean is an important problem both in paleoceanography and in modern oceanography. A long-standing question in paleoceanography concerns the evolution and consequences of the glacial meltwater delivered from the great ice sheets which covered a large fraction of North America and Europe during glacial periods. Although the associated rise in mean sea level of about 130 m has long been estimated, the pathways and impacts of the glacial meltwater for ocean circulation and climate remain poorly understood. Notably, the ocean components of climate models do not generally have a spatial resolution that is fine enough to properly simulate coastal phenomena which are known to contribute to the offshore export of shelf water in the modern ocean.Here we apply a regional eddy-revolving numerical model of ocean circulation in order to explore the pathways of glacial meltwater emanating from the St. Lawrence Channel – a major ice stream of the Laurentide Ice Sheet of North America during the last glacial period. Emphasis is placed on the offshore entrainment of glacial water by the Gulf Stream (GS), which according to paleoceanographic observations detached from the continental slope near Cape Hatteras, as it does today. First, a simulation of the eddying circulation in the glacial western North Atlantic is obtained by integrating the regional model to statistical steady state under glacial atmospheric forcing. Second, a series of glacial water discharge experiments are conducted for various assumptions about the discharge, including its volume transport, its density, and its seasonal timing. Mechanisms of glacial water export away from the slope are identified, such as the eastward entrainment by (anticyclonic) warm core rings and the subsequent incorporation of the glacial water into the GS offshore. The implications of our results for the interpretation of sediment records from the Laurentian Fan and for the simulation of glacial water discharges in paleoclimate models are then clarified.
Assessment of remote sensed data for weed species recognition in agricultural fields.
Authors: Nxumalo Gift
Published: February 2023

Accurate geographical and temporal information is provided in large part by remote sensing. Advanced crop protection plans can be created by gathering and analysing data at various scales and resolutions to create emergency models, identification patterns, and site mapping. Recent developments in remote sensing enable the analysis and diagnosis of crop problems based on reflectance data through visible, multispectral, or hyperspectral detection utilizing very high-resolution satellites.The strenuous physical removal of weed species based on field scouting is one management technique. The optimization method based on remote sensing predictions, fed by meteorological data, but also using vegetation information from several high-resolution remote sensing products and spectral data from different sensor types, combining them by data assimilation, is a novel aspect of the research. This method is used to optimize accurate weed detection and reliable discrimination between weeds and crop plants. By examining the spatial and spectral properties of the agricultural field, I will analyse the function of LIDAR and other time series remote sensing data in the field scouting (partly based on field surveys at the Hungarian case study site). The findings will establish a link between water, energy, and food production in agriculture and serve as the foundation for the creation of practical strategies for gathering data on target areas and making spatially selective weed control decisions.
Strategies for karst groundwater flow characterization in remote, mountainous, snowmelt-dominated catchments
Authors: Lilley Sara , Hayashi Masaki
Published: February 2023

The Front Ranges of the Canadian Rockies are home to extensive carbonate assemblages that host karst aquifers. New caves and karst springs have recently been discovered in the mountains from Banff, Alberta extending all the way to the United States border, although little research has been conducted on them due to the challenging terrain. In this study, we focus on the Watridge Karst Spring, which is located on a forested hillside in a mountain range that reaches an elevation of 3400 m. This perennial spring can discharge up to 3000 L/s. Karst catchments in these snowmelt-dominated, glacierized areas have sparse vegetation, heavy snowfall, and high hydraulic gradients, leading to efficient groundwater infiltration. As a result, the hydrochemistry of these springs often exhibits strong and rapid fluctuations. The effects of rapid conduit flow are expressed at the Watridge Karst Spring by an increase in discharge followed by a lagged decrease in electrical conductivity (EC), occurring over a diurnal-scale and a longer-scale (e.g., episodic snowmelt or heavy storm). This research aims to use hydrologically relevant metrics to understand the recharge, flow paths, and storage capacity of the aquifer. Particularly, we used signal processing of the fluctuations in discharge, EC and air temperature to estimate groundwater response time, defined here as the lag time between a hydrologic event and a resulting change in hydrochemistry. Response time can be used to approximate celerity in the case of discharge, and velocity in the case of EC. Additionally, automatic water sampling allowed for the observation of rapid changes in major ion chemistry.The results yielded an estimated groundwater conduit velocity on the order of 0.1 m/s that steadily decreases with diminishing flow. It was also found that a distinct shift in the EC signal phase and an associated change in mineral dissolution marks the drainage of an overflow conduit path. This is supported by dye tracer experiments of up to 14 km distance where a maximum velocity of 0.14 m/s has been recorded. Our results show that continuous hydrochemical monitoring of discharge and meteorological conditions at a high-temporal resolution can be used as a first step in characterizing conduit system response. For alpine karst springs with strong hydrochemical fluctuations, this strategy may limit the need to conduct tracer tests involving laborious field work in remote, mountainous locations.
Geo-tourism and Geodiversity of geoparks – a demonstration at Penghu Marine Geopark
Authors: Lin Jiun-Chuan
Published: February 2023

AbstractThe aims of this study is to demonstrate the adaptation of geopark concept for the geo-tourism and geodiversity at Penghu Marine Geopark.By adopting the idea of geopark from the UNESCO, Taiwan revised the Cultural heritage preservation law to add geopark concept in 2016. Penghu Archipelago was designed as marine geopark since 2020. By law, it is a way toward to local sustainable development.To promote geo-tourism, the Penghu National Scenic Area Administration, as management agency of geopark, is trying to introduce landscape explanation software and to improve the knowledge of local community associations, tour guides and volunteers. The goals are to transform the Penghu Islands into a high-quality geopark and ensure sustainability. This paper tries to discuss what is the way for local geo-tourism. Penghu Marine Geopark is a typical example. The methodology used in this paper are:To review the natural background and potential hazards of the environment. Because of tropical marine environment, Penghu owns unique basaltic landscape and a kind of geodiversity. However, it is important to find a way for landscape conservation, to prevent and reduce the impact of natural hazards, such as coastal erosion and landslide.
To promote local community to enhance the capability of promoting geo-product. Penghu is famous for its marine environment and good quality fish product. It is an important natural resource for whole community.
 This paper tries to demonstrate:How Penghu islands adapt winter monsoon and summer tropical cyclone. During extreme weather condition, the needs for water resources, electricity and food will be the first priority.
Coastal erosion is another issue. To reduce the impact of coastal hazards, how local people and government try to introduce such concepts through environmental education to raise the capability of resilience.
For water resources, desalination facilities are getting more and more important engineering for the Penghu islands. It is a necessary to prepare such engineering works in advance. Local geo-tourism can only achieve after the problems are solved. For local sustainable development, it will need technical support including water, energy and food resources. It is also need to reduce the damage from the impact of climate change and natural hazards to meet the SDGs goals.
 
Enhancing protected areas for climate refugia in the Qinghai-Tibet Plateau
Authors: Hua Ting , Zhao Wenwu , Cherubini Francesco , Hu Xiangping , Pereira Paulo
Published: February 2023

Protected areas (PAs) are the critical societal tool to conserve biodiversity, while rapid climate change potentially threatens the ecological outcomes of PAs. Therefore, targeting conservation and adaptation efforts necessitate a well-understand of the relationship between PAs and climate refugia. it is defined as buffer regions for species against exposure to climate change. Previous studies to identify climate refugia mainly relied on terrain-based metrics or climatic velocity, which ignore the ecosystem’s internal processes. To promote more biologically meaningful climate adaptation solutions, efforts need to be made to incorporate internal and external ecological processes to improve climate refugia identification. This work identified climate refugia in the Qinghai-Tibet Plateau (QTP), based on environmental diversity, phenology stability, and climatic velocity. It highlights the capacity to cope with extreme weather events, synchronization with plant growth cycles, and future climate adaptation, respectively. The results show that the climate refugia identified by environmental diversity, climatic velocity, and phenology stability indicators differed substantially, indicating the possible absence of functional complementarity of climate adaptation. Furthermore, existing PAs have notable conservation gaps for these refugia identified, particularly in the southeastern part of QTP. It highlighted the urgency of strengthening PAs for climate refugia in the QTP. Our work provides a comprehensive understanding of climate refugia, which can support better climate-driven conservation policies in the face of global warming.
Analysis of the diurnal and seasonal variations of NEE exchange over a large lake, a small lake and meadow surface of Lake Nam Co basin, Tibetan Plateau
Authors: Li Weimo , Wang Binbin
Published: February 2023

Saline lakes play an important role in the global carbon cycle by burying carbon in sediments and emitting CO2 to the atmosphere. A series of recent studies have found that Saline lakes of the Tibetan Plateau (TP) have a strong carbon sink function, which exhibits very different characteristics from lakes in other regions of the world.A period of five-year data recorded by the eddy covariance (EC) systems built at Lake Nam-Co (“large lake”, area: more than 2000 km2), Lake small Nam-Co (“small lake”, area: 1.4 km2) and Nam-Co land site (“land station”, plateau meadow) have been used to study on net ecosystem exchange (NEE) characteristics over the different underlying surfaces at Lake Nam-Co Basin. The results revealed that significant differences exist in their carbon exchange processes at diurnal and seasonal variations. (1) CO2  uptake in “large lake” occurs mainly during the freeze period, and the NEE uptake at the “land station” appears mainly in spring and summer, while “small lake” has no significant CO2 uptake during the winter ice covered season。(2) “Large lake” has significant intra-day variation during the ice-forming season; the “land station” has close to zero values in winter but shows significant intra-day variation in spring and summer for the NEE exchange, while the “small lake” shows significant differences for wind direction from the water and from the surrounding land. Under global climate change, the lakes over the TP have expanded a large proportion right now and will continue to enlarge in the future. Our study revealed that there are significant differences in the functions of CO2 source/sink between lakes and land, and even in different sizes of lakes on the TP. This will provide an important reference for the prediction and estimation of the carbon function changes of lakes on the TP.
Impact ejecta glass records atmospheric columnar disruption and strong E-field
Authors: Harris Thomas
Published: February 2023

Tektites are a naturally occurring form of cosmic impact ejecta, produced in ~ 2 or 3% of impact events from melted and mixed silicate sediments that are launched into space where they devolatilize and quench to solid glass.  Australasian tektites (AAT) make up the largest and most recent of the known tektite strewnfields, covering ~1/4 of Earth’s surface with 30 to 60 billion tons of melt glass.  In southeast Asia, the Indochinite sub-family of these glassy objects appear mainly as fractured and sometimes contorted fragments of formerly hollow spheroid predecessors.  Surface textures, bulk and detailed morphometrics of Indochinite fragment-form tektites record a tortured history that is not consistent with mere hypersonic atmospheric reentry into a standard atmospheric column.  The tektites show rapid bulk reheating and surface effects consistent with high-voltage arcing disruption.  The overall region where these fragment-form tektites fell has a surface that was laterized within hours of their arrival, pulsed with heat and moisture to the point of degrading the rocks and soil the tektites lie within.  Clear ablation signatures on symmetric ablated spheroid AAT of Australia and the Central Indian Ocean basin indicate their source as the N. American Great Lakes region.  The Marine Isotope Stage MIS20 epoch (deep ice age) of the event and Michigan Basin geology suggest several thousand cubic km of disrupted Laurentide Ice Sheet may have been injected across the exosphere via oblique ricochet impact, lingering as degenerate byproducts for a day or more.  High-potential E-field and regional disruption of the atmospheric column from exosphere to surface over southeast Asia is indicated.
The spatial-temporal variations of rainfall-streamflow linkage across North America: A functional data analysis approach
Authors: Ameli Ali , Janssen Joseph , Meng Shizhe , Cao Jiguo , Welch William
Published: February 2023

Achieving improved predictions in ungauged-basins or inferring the effects of climate and land-use changes on streamflow requires hydrologists to first learn the underlying mechanisms behind streamflow generation in gauged-basins. One way to characterize streamflow generation is by quantifying how catchments filter rainfall into streamflow. A simple and popular technique that displays the rainfall-streamflow linkage is the unit hydrograph. Though one could characterize and classify catchments based on their unit hydrographs, this approach implicitly implies that the function and response-time that link rainfall to streamflow are time-invariant. The celerity, and the function that links rainfall to streamflow in a given catchment, could vary from catchment to catchment as well as from season to season. This is primarily due to variations in antecedent wetness, temperature, vegetation transpiration and the ways climatic factors interact with biophysical factors, over time and over space. In this study, we utilize sparse historical functional linear models to quantify the time-variant rainfall-streamflow response function, across hundreds of catchments in North America. The function reflects the temporally varying relationship between rainfall and streamflow and can be used to infer temporally varying response times. We then attempt to relate catchment characteristics such geology, climate, and topography to the characteristics of rainfall-streamflow response function and response time, spatially and temporally.  We argue that our study extracts generalizable and robust process understanding in a novel data-driven manner.
Research on the Annual Water Dispatch Model of the Yangtze-to-Huaihe River
Authors: Zhang Lina , Lei Xaohui , Wang Chao , Ji Yi , Sun Jiahui
Published: February 2023

The project of the Yangtze-to-Huaihe River diversion focuses on urban and rural water supply, taking into both irrigation and water supply as well as improving the ecology of Chaohu Lake. It is a major strategic water resource allocation project across river basins and across provinces. This study used a combination of a simulation model and optimization technology to establish an annual water dispatch model based on the principle of water balance for the Yangtze-to-Huaihe River diversion project and employs genetic algorithms to optimize the proportion of the two-line river diversion for the section of Yangtze River-to-Chao lake. The possible scenarios of the annual water dispatching model were analyzed from two aspects of runoff water condition and water use planning, and typical years scheduling scenarios were established, including short-term planning and long-term planning of low flow years, short-term planning and long-term planning of normal flow years, and short-term planning and long-term planning of high flow years. The annual water dispatch model was used to simulate the annual scheduling schemes for these different scenarios, and the results of water diversion and water supply, divisional scheduling, and lake storage conditions were compared and analyzed for scheduling schemes. The simulation results showed that the water shortage in the near-term planning level year (2030) and the long-term planning level year (2040) was basically zero in the flat water year and the abundant water year, and there was a large water shortage in the dry water year in both the near-term and long-term planning level years, mainly in agriculture. The total amount of water diversions for each typical year in the scheduling scheme was thus significantly reduced compared with that in the design plan. In the far and near future planning, the abandoned water was less in the dry water year and relatively more in the rich water year and the flat water year, and the abandoned water was similar in the two lakes in the flat water year, while the abandoned water mainly occurs in Chaohu Lake in the rich water year. The northern section of the river was the main object of the water supply of the river-supply project, and the supply of this section accounts for about 57% of the total amount in the dry water year, more than 75% of the total amount in the flat water year, and more than 97% of the total amount in the rich water year. From the viewpoint of the whole section of the project, the water supply in the dry water year was the largest, the lake utilization in the flat water year was the largest, and the abandonment rate in the abundant water year is the largest under the near and long term planning. The results of this study can provide a certain foundation and reference value for the construction of project scheduling operation and scheduling system.
Mysterious geomagnetic response to minor solar wind disturbance: Observations
Authors: Dimitrakoudis Stavros , Yamauchi Masatoshi , Magnar G. Johnsen , Philippe Escoubet , Tohru Araki , Tero Raita , Ian R. Mann , Iannis Dandouras , Per-Arne Lindqvist , Christopher M. Carr
Published: February 2023

On 15 April 2022, the Kiruna magnetometer detected an isolated geomagnetic spike of 400 nT with rising time of 2 minutes. This is on the same level of large sudden commencements (historically largest one is about 1000 nT in Kiruna), but this event was not followed by any magnetic storm or substorm.  In this sense, the observed 400 nT spike is unique in the history of Kiruna magnetometer (more than 30 years of digital data). At the same time, the Kiruna riometer detected a strong absorption with short rise time, indicating a sudden increase of the electron density.  The world-wide geomagnetic observations available at IMAGE, SuperMAG and INTERMAGNET geomagnetic networks, show isolated localised geomagnetic spikes in the dawn sector in both hemispheres, but not in the dusk sector, gradually moving toward midnight with decreasing intensity.  Detailed analyses of geomagnetic deviation in the northern hemisphere indicates strong shear in the ionospheric Hall current with the sense of downward field.  Considering its location and electron density increase, this field-aligned current is most likely caused by the ring current particles, as is indicated by DMSP data. The solar wind velocity is constant with no specific variation that can cause such a unique event.  However, multi-spacecraft observations by SOHO, DSCOVR, ACE, Cluster and MMS suggest the possibility of a very localized IMF structure.  We thank magnetic stations of IMAGE, SuperMAG and INTERMAGNET network, and SOHO, DSCOVR, ACE, Cluster, DMSP and MMS team for providing data.
Experimental design for the the 2nd marine ice sheet and ocean model intercomparison project (MISOMIP2)
Authors: Jourdain Nicolas , De Rydt Jan , Nakayama Yoshihiro , Timmermann Ralph , Van Caspel Mathias
Published: February 2023

The 2nd Marine Ice Sheet and Ocean Model Intercomparison Project (MISOMIP2) is a natural progression of previous and ongoing model intercomparison exercises that have focused on the simulation of ice-sheet--ocean processes in Antarctica. The previous exercises motivate the move towards more realistic configurations and more diverse model parameters and resolutions. The first objective of MISOMIP2 is to investigate the robustness of ocean and ocean--ice-sheet models in a range of Antarctic environments, through comparisons to interannual observational data. We will assess the status of ocean--ice-sheet modelling as a community and identify common characteristics of models that are best able to capture observed features. As models are highly tuned based on present-day data, we will also compare their sensitivity to abrupt atmospheric perturbations leading to either very warm or slightly warmer ocean conditions than present-day. The approach of MISOMIP2 is to welcome contributions of models as they are, but we request standardised variables and common grids for the outputs. There will be two target regions, the Amundsen Sea and the Weddell Sea, chosen because they describe two extremely different ocean environments and have been relatively well observed compared to other parts of Antarctica. An observational "MIPkit" is provided to evaluate ocean and ice sheet models in these two regions.
An ion beam system for calibration of space low-energy ion detectors based on Kaufman ion source
Authors: Li Yiren , Miao Bin , Hao Xinjun , Liu Kai , Pan Zonghao , Zhang Tielong , Wang Yuming
Published: February 2023

Low energy ion detection in space is one of the important directions of space science detection. An accurate calibration of this type of instrument is necessary to ensure the effectiveness and scientificity of the obtained data. And the ion source is the most critical equipment in a calibration facility. In this study, an ion beam system based on Kaufman ion source is designed, which can meet the ground calibration of space low-energy ion detection instrument in the low-energy range of 100-1000eV. The experimental research shows that when the beam intensity of the ion source is about 100mA, the Faraday Cup collects about 1mA of current, and the generated ion beam fluctuates less than 5% within 60 minutes, which can meet the ground calibration requirements of space low-energy ion detection instruments.
Hyper resolution hydrological modeling: the need and benefit of improving spatial resolutions of global models
Authors: van Jaarsveld Barry , Dunn Frances , Sutanudjaja Edwin H. , van Beek Rens , Bierkens Marc F. P. , Wanders Niko
Published: February 2023

If not addressed and remedied, the unsustainable use of non-renewable groundwater will negatively impact many future generations. To effectively manage global groundwater reserves, we first need accurate estimates of its current availability and how much of this we can feasibly extract. Landscape characteristics have a high impact on local groundwater recharge, groundwater-surface water interactions, and abstractions. It is therefore key to model groundwater at an appropriate spatial resolution so that landscape heterogeneities are captured. Our objective is to enable groundwater modelling at fine spatial (~ 1 km) resolution, with the final aim to assess the physical limits of groundwater withdrawal by providing the first global estimates of fresh groundwater availability (attainable volumes and supply) subject to past human water use. The first step to attaining this objective is the ability to simulate groundwater recharge and surface water levels at 1 km spatial resolution using a global hydrological model. In this study, we aim to tackle this challenge and present the first global case of the PCR-GLOBWB at the 1 km spatial resolution. To do this, we implemented a statistical downscaling routine for meteorological forcing, created a new global 1km land surface parameterization and improved the parallelization of the PCR-GLOBWB model. The meteorological downscaling approach followed here provides outputs that are at a finer resolution than the original meteorological forcing products. This approach relies on Worldclim data to provide realistic sub-grid distributions of precipitation and temperature. In addition, sub-grid distributions of potential reference evaporation were retrieved from the Global Aridity Index and Potential Evapotranspiration Climate Database, which uses Worldclim data to calculate potential reference evaporation following the Penman-Monteith formulation.We investigate whether these high-resolution meteorological fields, in combination with an improved 1km land surface parameterization, provided improved outcomes by validating against remote sensing observations (soil moisture, total water storage) and local observations of discharge and compare these to simulation at coarser 10 & 50km resolutions. Furthermore, we discuss the computational challenges encountered along the way and outline future directions and opportunities in high-resolution groundwater modelling.
Stochastic data adapted AMOC box models
Authors: Chapman Ruth , Ashwin Peter , Wood Richard
Published: February 2023

The Atlantic Meridional overturning Circulation is responsible for the comparatively temperate climate found in Western Europe, and its previous collapse thought to have triggered glacial periods seen in the paleo data. This is a system that has multiple stable states- referred to as ‘on’ when the circulation is strong as in the current climate, and ‘off’ when it is much weaker. The AMOC has tipping points between these states. Tipping points occur when a rapid shift in dynamics happens in response to a relatively small change in a parameter. Making future projections of AMOC response to the climate is essential for avoiding any anthropogenic caused tipping, but it is computationally expensive to calculate the full hysteresis for different scenarios. This work looks at a conceptual five box model of the AMOC [1] which is easy to understand and cheap to implement. Previous work has considered bifurcation and rate-dependent tipping [2] of this model. This current work looks to estimate a realistic amount of noise from various GCM data sets and apply this to the model. We compare the covariance of the salinity data for a variety of CMIP6 models, and we compare the amount of noise covariance found in each data set, and how this can be input back into the box model. We perform some analysis to suggest where in the model the largest noise sources should be found.[1] Wood, R. et.al. (2019), Climate Dynamics, 53(11), 6815-6834[2] Alkhayuon, H. et.al. (2019), Proc. R. Soc. A, 475(2225)
Long term hydrological dynamics of an Alpine glacier
Authors: Zanoni Maria Grazia , Stella Elisa , Bellin Alberto
Published: February 2023

Several studies have been showing that major environmental changes will occur in mountainous regions, with dramatic effects in glacierized areas. In particular, the Alps are experiencing a sharper rising in air temperature, compared to other regions. The European Alps are water towers providing fresh water to highly populated areas in a fragile environment with ecosystems and human activities that adapted to low flow and storage in winter followed by high flow in summer. This dynamic is in phase with agricultural use and touristic needs while hydropower makes use of reservoirs to allowflexibility and increase production in the most profitable periods. Climate change may significantly impact this timing, thereby changing the scenario and introducing new challenges in water resources management.In the present work, we comprehensively analyzed the long-term (1976-2019) meteorological and streamflow time series of a small (8.5 km2) Alpine glacierized catchment, fed by the Careser glacier, in Peio valley, Italy. A Dense Deep feed-forward Neural Network (DNN) was employed to gap-fill the daily time series of the streamflow, available since 1976. Daily temperature and monthly precipitations at the glacier were obtained by interpolating the measurements at the 32 closest meteorological stations by Kriging with the External Drift.The resulting reconstructed time series were used to investigate the changes in streamflow from 1976. The analysis revealed that precipitation did not change significantly in the observed period. On the contrary, a statistically significant temperature increase was observed (∆T = 0.022, 0.052, 0.046 oC y−1 for the maximum, minimum and mean daily temperatures), which is, therefore, the main driver of the observed changes in the streamflow. Ablation, in terms of loss of glacier thickness, continued to increase, but the glacier’s contribution to summer runoff first increased, up to the middle of the nineties of the previous century, and successively decreased dramatically as an effect of the reduction of the glacier area. In addition, significant anticipation of the summer streamflow peak was observed in the last decade.The proposed analysis evidenced how the rise of temperature in the Alpine region is already having a profound impact on streamflow seasonality, which is expected to exacerbate in the near future, given the projected further increase of the temperature. More from a technical point of view, the combination of classical geostatistical methods with DNN allowed a reliable reconstruction of meteorological and hydrological missing data. The algorithms developed in this study can be easily exported in other similar situations.
Application of Ocean Bottom Seismometer: Study of the 4 Aug 2021 southernmost Okinawa Trough M6.1 event.
Authors: Wang Shiou-Ya , Hsu Shu-Kun , Wu Min-Rui , Liang Chin-Wei , Cho Yen-Yu
Published: February 2023

The Southern Okinawa Trough (SOT) is a back-arc-basin and characterized by an active normal faulting system and magmatic activity. Most seismic activities beneath the Southern Okinawa Trough at shallow depths (<30 km) are located about 50 km east of Ilan Plain (122.15°E - 122.55°E).  The seismic rate has increased significantly after May 2021. An earthquake struck offshore area of Ilan Plain on 4 August (0804 earthquake). Its magnitude of 6.1 at 7.0 km made it one of the rare, extremely powerful quakes ever before in the study area. However, the cause and mechanism are still unclear and worthy of further investigation. Furthermore, the previous study shows that submarine landslides have occurred in the northern continental margin of SOT. The frequent earthquakes will raise the risk of slope failure and may generate a local tsunami causing damage around the northeast coast of Taiwan. In order to explore the generation of 0804 earthquake, we have deployed an Ocean Bottom Seismometer (OBS) network to capture the seismicity around the study area.  In total, 852 events have been relocated and most of them are located in the high positive magnetic anomaly zone. The distributions of the earthquake show an NW-SE trending direction and may be related to the magmatic activity.  
Using information entropy to optimise and communicate certainty of continental scale tectonic models
Authors: Stål Tobias , Reading Anya M. , Cracknell Matthew J. , Ebbing Jörg , Halpin Jacqueline A. , Kelly Ian D. , MacKie Emma J. , Sobh Mohamed , Turner Ross J. , Whittaker Joanne M.
Published: February 2023

Antarctic subglacial properties impact geothermal heat, subglacial sedimentation, and glacial isostatic adjustment; critical parameters for predicting the ice sheet's response to warming oceans. However, the tectonic architecture of the Antarctic interior is unresolved, with results dependent on datasets or extrapolation used. Most existing deterministic suggestions are derived from qualitative observations and often presented as robust results; however, they hide possible alternative interpretations. Using information entropy as a measure of certainty, we present a robust tectonic segmentation model generated from similarity analysis of multiple geophysical and geological datasets. The use of information entropy provides us with an unbiased and transparent metric to communicate the ambiguities from the uncertainties of qualitative classifications. Information theory also allows us to test and optimise the methods and data to evaluate how choices impact the distribution of alternative output maps. We further discuss how this metric can quantify the predictive power of parameters as a function of regions with different tectonic settings.
Multiphase buffer theory: explanations of contrasts in atmospheric aerosol acidity and its applications
Authors: Zheng Guangjie
Published: February 2023

Acidity is one central parameter in atmospheric multiphase reactions, and strongly influences the climate, ecological and health effects of aerosols. Yet, the drivers of aerosol pH remain to be fully resolved. Here we investigated into this issue with thermodynamic models and observations. We find that aerosol pH levels in populated continental regions are widely buffered by the conjugate acid-base pair NH4+/NH3, and in aerosols an individual buffering agent can adopt different buffer pH values. To explain these large shifts of buffer pH, we propose a multiphase buffer theory, and show that aerosol water content and mass concentration play a more important role in determining aerosol pH in ammonia-buffered regions than variations in particle chemical composition. These results imply that aerosol pH and atmospheric multiphase chemistry are strongly affected by the pervasive human influence on ammonia emissions and the nitrogen cycle in the Anthropocene. We further investigated into the applications of the multiphase buffer theory. Exemplary applications include to help explain the formation of severe hazes in China, to quantify the contribution of different factors in driving the aerosol pH variations, and to provide the framework to reconstruct long-term trends and spatial variations of aerosol pH, etc. Further investigations on its applications in aerosol and cloud chemistry studies are needed.