bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Simulation of Spaceborne Range-resolved Differential Absorption Lidar System For CO2 Profile Detection At 1.57μm and 2.05μm Wavelength Scenarios
Authors: Hu Luojia , Yu Zhitong , Huang Yan , Ma Rong
Published: February 2023

The increasing atmospheric carbon dioxide (CO2) is the most important factor forcing climate change. However, due to lack of observation data about large-scale range-resolved CO2, there remains substantial uncertainty in current global atmospheric CO2 budget, which hinders giving insight into CO2 cycle and modeling its forcing to climate change. Space-based range-resolved differential absorption lidar (range-resolved DIAL), is a promising and powerful means for obtaining large-scale range-resolved CO2 data, but has been rarely studied. Prior to developing spaceborne range-resolved DIAL, a preliminary study on optimization of on/off-line wavelengths must be performed to ensure high signal-to-noise (SNR), high sensitivity to near surface region and minimize the interference of atmospheric factors. This study aims to find the optimum wavelength scenarios in terms of random errors determined by SNR, weighting functions used to assess sensitivity to near-surface region, and systematic errors affected by atmospheric factors. Firstly, we find the optimal on/off-line wavelengths at 1.57μm and 2.05μm, which are widely used and show good results for measuring CO2 concentration, after estimating on-line and off-line wavenumbers separately using evaluation indexes called  and . Furthermore, we get the optimum wavelength scenarios of spaceborne range-resolved DIAL by comparing the random, systematic errors and weighting functions of optimal on-line and off-line wavelengths at 1.57μm and 2.05μm. Results show that the wavelength scenario at 2.05μm is the optimal for spaceborne range-resolved CO2 detection. To satisfy the requirement that the relative random errors are smaller than 0.01 (<1%), systems at 2.05μm wavelength scenario with vertical resolution of 0.5 km, 0.7 km, 0.8 km, 0.9 km separately require that SNR values of on-line wavelength at 0 km height are larger than 10, 9, 8, 7.
Droplet Growth and Its Impact on Visibility During Freezing Fog Events from CFACT
Authors: Durmus Onur , Gultepe Ismail , Pu Zhaoxia , Hoch Sebastian , Pardyjak Eric , Hallar Anna Gannet , Perelet Alexi
Published: February 2023

Freezing fog is a type of cold fog that forms when the air temperature (Ta) is below 0℃. Although Ta is below 0℃, the water droplets can remain in a liquid state rather than freezing. Freezing-fog conditions can pose a significant hazard to aviation and marine operations because it can reduce visibility severely, and ice accumulates rapidly on the surfaces such as aircraft, ship, and roads. Observations collected during the CFACT (Cold Fog Amongst Complex Terrain) Project from 7 January – 24 February, representing cold-fog events over Heber Valley of Utah, are used in the analysis. The objectives of this study are to characterize freezing fog microstructure in detail with respect to droplet size distribution, critical diameter related to activation, and visibility. In the analysis, freezing fog (FZFG) and droplet size spectra will be examined theoretically and experimentally. The droplet activation and critical diameter forming in frozen-fog droplets will be revealed using the Köhler curve. The effect of the droplet-growth process on visibility changes for two cold-fog cases is examined and results are discussed. Preliminary analysis suggests that freezing-fog droplet growth strongly depends on environmental conditions, including Ta, relative humidity (RH), and liquid water content (LWC) as well as droplet number concentration (Nd). It is concluded that microphysical parameterizations should investigate freezing-fog droplet formation and growth in more detail because presently it is lacking in NWP predictions. 
Using air quality sensor networks to compare variations of PM2.5 in a small town and a city in Ireland.
Authors: Byrne Rósín , Wenger John C , Hellebust Stig
Published: February 2023

High density air quality sensor (AQS) networks offer a unique opportunity to better understand the local variations and temporal patterns of air pollutant levels in a city. With the coordination of reference instrumentation and meteorological data, they are even more useful. This work compares two sensor networks that are the first or their kind in Ireland. The first is in Cork City (population ~ 220,000) in the south of Ireland, which currently has five regulatory monitoring stations, three of which monitor PM2.5. The second location is Edenderry which is a rural town (population ~ 8,000) in the Irish midlands served by one regulatory monitoring site. The Cork City AQS network is comprised solely of PurpleAir devices, while the Edenderry network combines both PurpleAir and Clarity Movement Co. devices. The networks provide increased spatial and temporal data in relation to PM2.5.Both locations experience seasonally elevated levels of PM2.5 due to higher instances of domestic solid fuel burning during the winter months. However, Edenderry generally experiences significantly higher levels, despite its much smaller size. During the winter heating period of 2020-2021 (01/10/20 - 31/0321), there were 23 instances where the PM2.5 24-hour mean at a regulatory monitoring site in Cork exceeded the WHO Global Air Quality Guidelines of 15 µg m-3, while there were 83 instances in Edenderry over the same period.A correction model was applied to the AQS data collected in both networks to align the values with respective local reference data. Multiple linear regression (MLR) models were used to calibrate the networks using data from periods of colocation of the reference instrument with air quality sensors. By combining these robustly calibrated and co-ordinated networks with local meteorological information, the data was used to investigate the local spatial and temporal variations in PM2.5 for the period 01/02/2022 to 29/07/2022. The typical daily cycle of PM pollution in Ireland was observed in both locations, with a dominant afternoon/evening peak during the colder months due to solid fuel burning for home heating. Significant PM2.5 variations between sensor locations in each network were found. The results showed that a small town in Ireland can experience PM2.5 pollution levels that are as substantially higher than more populated urban areas.This work was supported by the EU LIFE Programme through the project LIFE Emerald - LIFE19 GIE/IE/001101 and the Cork City AQS network is supported by Cork City Council.
Water vapor isotopic variations of the upper troposphere/ lower stratosphere in the N. American and Asian Summer Monsoons
Authors: KleinStern Carly , Clouser Benjamin , Bui Thaopaul , D'Amato Francesco , Viciani Silvia , Bianchini Giovanni , Thornberry Troy , Moyer Elisabeth
Published: February 2023

The 2022 ACCLIP (Asian summer monsoon Chemical and CLimate Impact Project) high-altitude aircraft campaign has provided a sampling of the diversity of processes that affect moisture transport in the upper troposphere / lower stratosphere (UT/LS). We report here on ACCLIP observations of water vapor isotopologues, which trace the origin and microphysical history of water vapor. Measurements with the Chicago Water Isotope Instrument (ChiWIS) show isotopic variations in the UT/LS that correlate with airmass history, and 100-150 ‰ variation even at the same water content. ACCLIP flights out of Osan, South Korea sampled monsoon anticyclone outflow with CO values over 200 ppb, recent local convection, extensive in-situ cirrus, and an overflight of tropical cyclone Hinnanmor showing strong isotopic depletion. Flights out of Houston, TX  sampled week-old remnants of sublimated ice from deep convection, producing enriched vapor, and possible mixing of convective overshoots with stratospheric air before sinking. We show through case studies from both Asia and North America that isotopologues provide a sensitive diagnostic of ice sublimation, and demonstrate how different meteorological contexts produce distinct isotopic signatures.
The development of a detailed mineralogical database from satellite remote sensing products, towards an improved representation of dust transport in NWP simulations.
Authors: Bartsotas Nikolaos S. , Sykioti Olga , Spyrou Christos , Douvis Kostas C. , Amiridis Vassilis , Zerefos Christos , Solomos Stavros
Published: February 2023

A broad spectrum of environmental processes such as radiation, cloud formation, ocean fertilization and human health are affected from the presence of mineral dust. The transport of dust particles is dictated by the prevailing meteorological conditions as well as the composition and physiochemical properties of the particles themselves. Which, in turn, are bound to the soil mineralogy at the source region.Numerical weather prediction models can estimate the transport of dust particles, yet a more refined mineralogical categorization can significantly improve the dust transport estimations and  increase preparedness for implications on weather, biogeochemistry and health. This novel mineralogical representation is derived from multi-spectral satellite remote sensing sensors (Sentinel 2A) over a limited area around Lake Chad in Sahara desert by taking into account dust particle characteristics such as size, composition and optical properties. The mineralogy map will be implemented in WRF/CHEM model to improve the accuracy of atmospheric simulations. The final product will be juxtaposed against current state-of-the-art mineralogical products such as the NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) mission. Dust transport simulations will be compared against field measurements from Antikythera PANGEA station in the Mediterranean and ASKOS campaign in the Atlantic Ocean.
Time Series Change Analysis of Urban Heat Mitigation Capacity Using the InVEST Urban Cooling Model : Focused on Jeju Special Self-Governing Province
Authors: Lee Eunsun , Lee Eunjeong , Jang Raeik , Sung Hyun Chan , Jeon Seong-Woo
Published: February 2023

Urban heat island is a phenomenon in which the temperature of urbanized areas is higher than that of other surrounding areas. Urban heat islands are caused by artificialization of surface cover, changes in urban shape, and increase in artificial arrangement, while Green space reduce the heat by lowering surface temperature due to reflection and evaporation of solar radiation.

This study targeted Jeju Island, which had the most heat waves and tropical nights in South Korea ,and evaluate the heat mitigation ability under the biological mechanism between the physical environment that generates urban heat and green space that reduce urban heat. In addition, the change in heat mitigation according to the change in the type of land cover over 30 years (late 1980s to late 2010s) was analyzed.

In this study, the InVEST urban cooling model was used to evaluate the heat mitigation ability in the city. The InVEST urban cooling model calculates an index of heat mitigation based on shade, evapotranspiration, and albedo, as well as distance from cooling islands.

As a result, From the late 1980s to the late 1990s, the area of Grade1 decreased by 63.79㎢ , while the area of Grade2(17.68㎢), Grade3(32.92㎢) , Grade4(8.10㎢), Grade 5(5.01㎢) are increased. And from the late 1990s to the late 2000s, the area of Grade1(37.51㎢), Grade3(0.88㎢), Grade4(1.35㎢) are decreased, while the area of Grade2(31.37㎢), Grade5(8.38㎢) are increased. Further more the late 2000s to the late 2010s, the area of Grade1 rapidly decreased by 501.57㎢, while the area of Grade2(368.59㎢), Grade3(102.46㎢) , Grade4(22.16㎢), Grade5(8.36㎢) are increased. Under the time series analysis, areas that are constantly vulnerable or show rapid grade changes can be viewed as vulnerable areas. It is necessary to establish the urban heat reduction policy, such as land cover changes and expanding green areas, in consideration of environmental characteristics, focusing on these vulnerable areas.

 

※ This work was supported by Korea Environment Industry &Technology Institute (KEITI) through "Climate Change R&D Project for New Climate Regime.", funded by Korea Ministry of Environment (MOE) (No. 202201344001)

 
The legacy effect of long-term management on greenhouse-gas fluxes in European croplands.
Authors: Esparza-Robles Ulises Ramon , Díaz-Pinés Eugenio , Lagomarsino Alessandra
Published: February 2023

In the frame of climate change mitigation, the effect of agricultural practices on soil organic carbon (SOC) stocks has been widely studied in different pedoclimatic conditions across Europe. Practices that have been identified as generally having a positive effect on SOC stocks include those increasing carbon inputs to the soil via external organic matter or via incorporation of crop residues. These practices also modify the soil N2O and CH4 fluxes; this is highly relevant for estimating the overall effect of management strategies on the soil greenhouse gas (GHG) balance, but so far, this aspect has not been assessed comprehensively. In this work, we make use of long-term experiments covering a large range of soil and environmental conditions in Europe. Further, the experiments were selected based on the management practices under investigation (addition of organic matter, crop residue management) and access to data on SOC stock changes as affected by management. Undisturbed soil samples were investigated for non-CO2 fluxes under controlled conditions. As research within the scope of global change, soils underwent a drying-and-rewetting cycle to study the soil response to extreme events in relation to the organic matter inputs. Our lab data provide relevant information on soil non-CO2 fluxes, which will be integrated with SOC stock change data, field GHG flux data and ancillary soil information. Overall, we will increase our understanding of soil processes towards identifying and promoting win-win scenarios between greenhouse gas fluxes and soil carbon storage in European croplands.
Experiences from co-designing a national soil policy with researchers, policy teams and farmers in Wales
Authors: Hannam Jacqueline , Sánchez-García Carmen , Button Erik
Published: February 2023

Since withdrawal from the European Union a series of reforms of agricultural policy are under development in the United Kingdom. There is currently no dedicated soil policy in Wales and the reforms provide an opportunity to devise a new position on soils that sets an ambition for the sustainable use of soils for future generations. To maximise soil policy adoption, we learnt from previous unsuccessful attempts to launch soil policies and developed a completely different approach to co-designing soil policy. We reflect on our experiences as researchers working in placements directly within government policy teams as a mechanism for soil policy development. This involved several different aspects of policy development and a wide range of actors. Key activities included an independent evidence review to ensure current scientific knowledge provided the foundation for the draft soil policy statement. The embedded nature of the researchers within the policy teams meant effective and fluid dialogue, building trusted relationships and the opportunity to challenge the potential bias within the policy teams regarding key evidence. Building consensus towards a draft soil policy statement was a major barrier to overcome. We used the concept of co-design with the policy team and other stakeholders (other policy teams, regulatory bodies, non-governmental organisations, and farmers) to further the development of the draft soil policy statement and to select key objectives for sustainable soil management relevant to Wales. The main outcomes from the placements were: understanding the policy context and mechanisms for policy development; presenting clear and concise evidence; managing complex relationships and challenging institutional structures.
Validation of coupled water, vapor and heat flow models with evaporation experiments
Authors: Iden Sascha , Blöcher Johanna , Diamantopoulos Efstathios , Durner Wolfgang
Published: February 2023

Evaporation from bare soil is an important hydrological process and part of the water and energy balances of land surfaces. Comprehensive modelling of this process must include coupled liquid, vapor and heat fluxes. Model concepts of varying complexity have been proposed to predict water loss from soil through evaporation. The objective of our study was to test a coupled water, vapor and heat flow model with data from laboratory evaporation experiments under different boundary conditions. Laboratory evaporation experiments were conducted with a sand and a silt loam under three atmospheric forcings. Pressure heads, soil temperature and the evaporation rates were monitored and the experiments were simulated with a coupled water, vapour and heat flow model which solves the surface energy balance and predicts the evaporation rates. The evaporation dynamics was well captured, in particular the onset of stage-two evaporation and the evaporation rates during stage-two. A valid description of the observed data required the use of a comprehensive model of the soil hydraulic properties which accounts for water adsorption and film flow. However, a slow continuous decrease in the measured evaporation rate during stage-one could not be described with the model under the assumption of a constant aerodynamic resistance. While the addition of established empirical soil resistance parametrizations significantly degraded model performance, the use of a boundary layer resistance improved the evaporation rate predictions for the sandy soil but not for the silt loam. Care should be taken when using resistance parametrizations in coupled modelling of bare soil evaporation.
Quantification of glacier flow velocities using time-lapse photogrammetry in conjunction with high-resolution digital elevation models
Authors: Mayrhofer Franziska , Grasemann Bernhard , Schöpfer Martin
Published: February 2023

Time-lapse photogrammetry in conjunction with high-resolution digital elevation models is used to quantify the surficial velocity field and the ablation of the Pasterze, a rapidly retreating alpine valley glacier in Austria. Three automatic time-lapse cameras were installed along the orographic left valley flank, c. 150 m above the glacier’s surface, to monitor retreat and ablation from July to September 2020. Although time-lapse photogrammetry offers spatial and temporal high-resolution data, the various processing steps to calculate the glacier’s velocity field are challenging. Digital image correlation of the time-lapse series photos is achieved using a published Python library (How et al. (2020) PyTrx: a Python-based monoscopic terrestrial photogrammetry toolset for glaciology. Frontiers in Earth Science 8:21, doi:10.3389/feart.2020.00021), which was adapted for the Pasterze data set. Typical time intervals for the digital image correlation were two to ten days. Factors that hamper computing flow velocities from time-lapse series photos alone are low contrast of the glacier’s surface and ablation rates exceeding the horizontal flow velocity. The latter problem is solved with the aid of two high-resolution digital elevation models (DEMs), which were calculated using 790 drone images from flight missions on July 13 and September 15 2020. The photogrammetric (Structure from Motion) software Agisoft Metashape (v. 1.8.4) is used to calculate the two DEMs from dense point clouds with a resolution of 5 cm/pixel. Linear interpolation of the glacier’s elevation between the July and September DEM was used to provide an approximate surface for a given date within the monitoring period. With this additional processing step, we can project tracked pixels from the digital image correlation process on an adapted DEM, which reflects the absolute height on a certain date best. Our workflow illustrates that time-lapse series photos taken obliquely to the glacier’s surface can be used to compute the surficial velocity field with the aid of digital elevation models that yield the glacier’s surface at the beginning and at the end of the monitoring period. In fact, the glacier’s velocity field computed in that fashion is consistent with direct measurements from a sparse network of stakes and mapped structures.
Short-Term Dynamics of the Flowing Stream Drainage Density
Authors: Bujak Izabela , van Meerveld Ilja , Rinaldo Andrea , von Freyberg Jana
Published: February 2023

Many headwater streams are non-perennial. The flowing stream network dynamically expands and contracts during and after rainfall events, resulting in temporal changes in the flowing stream drainage density (DD). This dynamic behavior has consequences for solute transport and the organisms that live in the streams. Therefore, it is important to understand the hydrological processes responsible for these changes in DD to better predict the impacts of climate change on riverine ecosystems. However, until now, our knowledge of event-scale DD dynamics is limited because experimental data remain sparse.We monitored DD in two 5-ha catchments in the Swiss Alpine foothills from June to October 2021. We installed a dense wireless sensor network to monitor the water levels in the streams and groundwater, soil moisture, and precipitation. In addition, we did multiple mapping surveys during different hydrological conditions and developed a simple model to calculate DD from these measurements at a 10-min resolution. We used these data to explore how short-term changes in DD relate to water storage in the catchments.Our surveys showed that during the wet 2021 summer, DD varied considerably both in space and time, ranging from 2.7 to 32.2 and 7.8 to 14.6 km/km2 for the flatter and steeper catchment, respectively. The model provided reliable estimates of DD variations at 10-min resolution for both catchments (accuracies >0.94). In the flatter catchment, the relations between DD and either discharge or groundwater became steeper when DD was larger than 20 km/km2.DD increased rapidly with wetter conditions when the groundwater levels rose to 20 cm from the surface and streamflow was initiated in multiple shallow-incised channels. From analyzing multiple consecutive rainfall events, we found that the discharge-DD relationship was counterclockwise when conditions were dry. This is likely caused by the streamflow coming from nearby the outlet where the topographic wetness index is high. Surface flow in the upstream tributaries emerges only once the maximum subsurface transport capacity is exceeded, causing a rapid increase in DD. After the rainfall ends, discharge recedes quickly, whereas DD remains high due to ongoing groundwater seepage at the channel heads. For events with wetter conditions, there was no hysteresis, likely because the maximum subsurface transport capacity is exceeded faster throughout the catchment. Such threshold behavior and hysteresis were also not observed for the steep catchment, where multiple groundwater springs were flowing throughout the study period, resulting in much smaller DD variations.
Validating Satellite Radar Altimetry-Derived Greenland Near-Surface Density and Surface Roughness using in situ and Airborne Datasets
Authors: Scanlan Kirk M. , Simonsen Sebastian B. , Rutishauser Anja , Vandecrux Baptiste
Published: February 2023

Recent research has demonstrated how Greenland Ice Sheet (GrIS) near-surface density and wavelength-scale surface roughness can be estimated from satellite radar altimetry surface echo powers by way of the Radar Statistical Reconnaissance (RSR) technique, the adoption of a radar backscattering model (i.e., the small perturbation model, SPM) and calibration using in situ density profiles. Patterns in the estimated density results 1) highlight an inter-annual variability that covaries with known climatic drivers (e.g., extremely warm 2012 Greenland summer temperatures) and 2) suggest that density estimates derived from different frequency radar echoes (Ku-band from ESA CryoSat-2 and Ka-band from CNES/ISRO SARAL) correspond to different depths in the near-surface (with Ku-band densities being deeper than those from Ka). When expressed as fractions of their respective signal wavelengths, the CryoSat-2 and SARAL surface roughness estimates 1) exhibit good agreement, 2) recover anticipated surface roughness conditions (i.e., a smooth GrIS interior and rougher margin) and 3) demonstrate minimal temporal variability.Here we present on-going work directed at validating both the use of the small perturbation model as well as the implied density-depth sensitivity in these new remote sensing observations. First, the suitability of the SPM is evaluated using the in situ density cores as well as airborne radar/laser altimetry measurements acquired along the EGIG line during the 2017 and 2019 ESA CryoVEx campaigns. Second, to quantify the depth range to which the satellite radar altimetry Ku- and Ka-band density estimates apply, we compare them against more than 400 contemporaneous (2011-2019) measured in situ density cores across the GrIS. These validation exercises are crucial to understanding the nature of these new satellite-based observations of the near-surface properties of the GrIS that, in turn, will facilitate more accurate estimations of the current and future GrIS mass balance.
Potential vorticity and surface layer stability in hurricane movement: case studies of Hurricanes Harvey and Ida
Authors: Khani Sina , Dawson Clinton N.
Published: February 2023

It has been known that potential vorticity (PV) diagnostics can be employed to (a) evaluate large-scale dynamics of hurricane movement, and (b) assess the storm’s influence on its own track. Moreover, PV variations and temperature adjustments at the tropospheric interior and the associated general circulation theory are closely related to the surface PV. Diagnosis of the surface PV is, however, complicated due to data availability/coarse-resolution configurations across the wide terrain in topographic regions. In this work we develop a high-resolution configuration for the Gulf of Mexico (GoM) region for employing in the Weather Research and Forecasting (WRF) model to study Hurricanes Harvey and Ida. The new configuration includes horizontal resolutions of 5 km and 1.67 km in the main and nest domains, respectively; 55 vertical heights (potential pressure levels) are also considered. Forecasts of Hurricane Harvey for 132-hours (5days + 12 hrs), and Hurricane Ida for 78-hours (3days + 6 hrs) are performed, and outputs are stored at every 15 minutes. It is shown that surface PV changes its sign when the Hurricane Harvey/Ida arrives over the land while PV at high altitudes are conserved. We show that the surface PV change is due to the change of vertical temperature gradient at the surface (i.e. change of surface layer stability). These dynamical evolutions are coincident with an increase in precipitation rate and accumulated precipitation of hurricane aftermath. We discuss how these meteorological processes can possibly influence hurricane movements.
A sedimentary and foraminiferal record of early to mid-Holocene environmental change from Singapore
Authors: Yan Yu Ting , Switzer Adam D. , Fontainer Christophe , Culver Stephen J. , Chua Stephen , Morgan Kyle , Dixit Yama , Horton Benjamin P.
Published: February 2023

In the context of warming climate and rising sea level, records from the early-to-mid Holocene provide important analogues to investigate how the environment responds to such changes. The Sunda shelf provides favourable conditions to reconstruct past environmental change as the presence of numerous large paleo-valley systems and high sedimentation rates allow transgressive deposits from the early-mid Holocene sea-level rise to accumulate continuously in topographic depressions.  To this end, we analysed the sedimentological, geochemical and micropaleontological characteristics of a sediment core (GRBH03) to investigate early-to-mid Holocene environmental changes in southern Singapore. We constrained the chronology with ten radiocarbon dates that were placed in Bchron age-depth model. Using a multi-proxy approach (e.g., grain size distribution, loss on ignition and XRF core-scanning), supported by benthic foraminifera, three sedimentary units were identified in GRBH03. Sedimentary unit I was found at the base of the core. This unit was characterised by a dark grey sandy silt unit deposited from about 9.0 to 8.9 cal ka BP. Few or no foraminifera were found in this unit, likely due to degradation of organic material. Sedimentary unit II was a blue-grey marine mud that was deposited between 8.8 and 5.8 cal ka BP. Within the marine mud unit, foraminiferal assemblages show a transition to shallow marine environment from about 8.8 to 6.4 cal ka BP as open marine species (e.g., Murrayinella murrayi and Bulimina sp. cf. B. marginata) become more abundant up-core. Subsequently, brackish species such as Muyrrayinella globosa and Ammonia veneta started to dominate mud unit assemblages, reflecting a transition from shallow marine to brackish environments, likely associated with decelerating sea level rise. The marine unit is then overlain by the sedimentary unit III, which is a shelly-silt unit deposited after 5.9 cal ka BP. This unit was mostly barren of foraminifera, which may be attributed to a high-energy marginal marine environment where conditions were unfavourable for foraminiferal preservation. Our study show that changes in sedimentary units and foraminiferal assemblages present in GRBH03 are linked to varying rate of relative sea-level rise during the early-to-mid Holocene. 
A new gap-filling method to avoid systematic bias in carbon balance estimates in northern ecosystems
Authors: Vekuri Henriikka , Tuovinen Juha-Pekka , Kulmala Liisa , Papale Dario , Kolari Pasi , Aurela Mika , Liski Jari , Laurila Tuomas , Lohila Annalea
Published: February 2023

Climate change mitigation requires – besides greenhouse gas emission reductions – actions to increase carbon sinks and storages in terrestrial ecosystems. However, quantification of sources and sinks of carbon depends on reliable estimates of the net ecosystem exchange of carbon dioxide (CO2). This also involves the eddy covariance technique (EC), a key method to directly measure the CO2 fluxes between ecosystems and the atmosphere. Various methods have been used to impute, or gap-fill, missing EC data and previous comparisons have shown that the accuracy of the best-performing methods, e.g. the widely-used marginal distribution sampling (MDS), is reaching the noise limit of measurements. However, knowledge on the performance of gap-filling methods is lacking from northern ecosystems.By analyzing an extensive global data set, we show that MDS causes significant carbon balance errors for northern ecosystems. MDS systematically overestimates the carbon dioxide (CO2) emissions of carbon sources and underestimates the CO2 sequestration of carbon sinks. We discuss reasons for the errors and show how a machine learning method called extreme gradient boosting or a modified version of MDS can be used to minimize the northern site bias.
Glaciers’ role as water resource in the Swiss Alps
Authors: Farinotti Daniel , Cremona Aaron , van Tiel Marit , Huss Matthias
Published: February 2023

In high-mountain environments such as the European Alps, glaciers are an important component of the water cycle. With ongoing climate change, this role seems in jeopardy though: glaciers in Switzerland, for example, have lost more than 30% of their volume since the year 2000, and future projections indicate a future with ice-free landscapes if society was to fail in taking immediate and stringent climate action.In this contribution, the role of glaciers as water resource will be reviewed. By taking the Swiss Alps as an example, their contribution to regional water supplies and usage will be quantified. A focus will be on the glaciers’ role in providing water during dry periods, as well as the relevance of glacier melt in the context of hydropower production.Based on both extended glaciological measurements collected in the frame of the Glacier Monitoring Switzerland (GLAMOS) program and daily glacier melt data retrieved through automated methods, we will for example quantify the meltwater contribution that glaciers had in the extremely hot summer 2022. The year saw a record-high 6% glacier volume loss and we show that individual heat waves contributed over-proportionally to this amount: 35% of the total summer ice loss, for example, occurred in the 25 hottest days, delivering a water amount that corresponds to 56% of the total summer melt seen on average for the past decade.Such phases of extreme melt can also be challenging for water resource management. In high-alpine rivers, where annual glacier contributions to streamflow were up to 80% in 2022, existing hydropower infrastructure can for example be overwhelmed. For a country that sees some 2.1kWh of hydro-electricity being produced for every cubic meter of glacier melt, this raises questions about future management strategies, and calls for robust projections of future streamflow.
Resistivity imaging of Mendocino Fracture Zone using marine magnetotelluric data
Authors: Wang Shunguo , Constable Steven , Reyes-ortega Valeria , Sandwell2 David T.
Published: February 2023

Seafloor fracture zones are the inactive extensions of transform faults that represent a discontinuity in seafloor age, temperature, and bathymetry. Their structures and tectonic features provide important information about lithospheric evolution. The age contrast across the fracture zone produces differential subsidence resulting in lithospheric flexure with uplift on the young side and subsidence on the old side. There is still debate on whether a fracture zone is significantly weaker than the surrounding lithosphere.  Some models predict small-scale convection beneath the FZ due to the sharp thermal contrast. A magnetotelluric (MT) survey over the Mendocino fracture zones (MFZ) was carried out 600 km away from the US west coast in 2018. The primary objective is to determine whether changes in the electrical resistivity across the MFZ are caused by temperature variations or other factors at the LAB. There is a strong crust age contrast at different sides of the MFZ. The northern side, younger with a crust age of 6.5 Ma, is formed at the Gorda Ridge with depths of about 3 km. The southern side, older with a crust age of 33 Ma, is part of the Pacific plate with depths of about 4 km. On both sides of MFZ, seamounts are observed in the study region, which indicates off-axis magma upwelling. Two-dimensional (2D) inversion of MT data was done to construct a 2D resistivity model across MFZ. The inversion can fit the data to an RMS of 1.8 with an error floor of 5 % on the MT impedance tensor. The model shows strong resistivity contrasts at the depths of 30-80 km on both sides of MFZ. The resistivity contrast at such depths is likely attributed to partial melt and temperature since composition is most likely similar at both sides of MFZ. Other conductive anomalies are also observed at shallow depths along the profile, which collocates with seamounts at the study region, especially near the southern end of our MT profile. Therefore, the conductive anomalies at the shallow depths likely present partial melts driven by upwelling magma.
Platinum-group elements of the Kuhjoch section (Austria) link the onsets of weathering of the Central Atlantic Magmatic Province and the end-Triassic mass extinction
Authors: Mortensen Heiðrikur , Andreasen Rasmus , Bodin Stéphane , Sanei Hamed , Ulrich Thomas , Richoz Sylvain , Lindström Sofie , Luguet Ambre , Tanner Lawrence , Tegner Christian
Published: February 2023

The end-Triassic mass extinction (ETME; c. 201.6 Ma), one of the so-called “big-five” mass extinctions in the Phanerozoic era, is associated with widespread marine anoxia, ocean acidification, global warming, carbon cycle perturbations (δ13C) and an extinction of diverse marine and terrestrial groups. This extinction is frequently linked to the volcanic activity in the Central Atlantic Magmatic Province (CAMP) which is often cited to explain e.g., the correlative negative carbon excursions across many sections, mutagenesis of land plants by Hg-toxicity, and enrichment of Hg/TOC. Despite this, the exact identification of a volcanic signal in many of these sections is not well constrained. In this study we present high-precision platinum group element (PGE: Ir, Ru, Pt, Pd) and Re data for the Triassic-Jurassic boundary succession at the Kuhjoch section (Austria). These are the first results from our new analytical setup using high-pressure asher digestion, isotope dilution and multi-collector inductively-coupled plasma mass spectrometry for precise determination in low concentration (e.g. ppt) samples such as sediments. The PGE and Re concentrations and patterns vary significantly with stratigraphy. The c. 13 m of clayey sediments above the onset of the extinction (marked by the c. 16 cm thick T-bed) show pronounced enrichment in Pt, Pd and Ir concentrations relative to the under- and overlying carbonate dominated stratigraphy. Their PGE patterns are non-chondritic with Pd/Ir and Pt/Ir similar to CAMP basalts. Normalised for lithology (Al2O3), however, there are no significant variations in Pt, Pd and Ir values below, within and above the clayey sediments. Re and Ru are, however, depleted compared to the other PGEs in the clayey interval, something also observed in some CAMP basalts. One possibility is therefore to interpret the PGE-rich, clayey sediments, including the main extinction interval in the basal portion, as recording increased weathering of CAMP basalts. As the PGE enrichment increases up through the T-bed, this could show that the onset of CAMP weathering and mass extinction would have therefore coincided. However, further work is needed to identify the relative role of CAMP volatile emission during volcanic activity versus post-eruption weathering of basalts.
Integrate human dynamics in disaster risk management: An agent-based approach to evaluate policy effectiveness
Authors: Lei Yu , Wu Shengnan
Published: February 2023

Although DRR (disaster risk reduction) policies have been proved effective in some regions, policy implementation lacks a sufficient evidence-based evaluation process. This study aimed to evaluate the effectiveness of DRR policies, including setting up early warning systems, constructing disaster shelters, and incentive mechanisms. By using the agent-based modeling (ABM) approach, a policy evaluation model was developed to integrate human individual differences during disaster events. The model was calibrated to simulate the DRR policy implementation in a debris flow event at Longchi town, China. The main findings are: 1) setting up an early warning system was the most effective measures and fundamental of community-based disaster risk management as the system had contributed to a 30.06% casualties reduction in the case of Longchi town; 2) individual perception on DRR policies was at large variance which influenced the policy effectiveness; 3) marginal benefits of policies to raise public willingness might decrease quickly. Therefore, individual perception and behaviors have a significant impact on the effectiveness of DRR. This study provided an evidence-based approach to the policy-makers to formulate the most cost-effective DRR policies.
Has the redressal mechanism for air pollution-related cases in India evolved since the inception of the National Green Tribunal?
Authors: Sekar Abinaya , Samad Muhammed Siddik Abdul , Varghese George K
Published: February 2023

The National Green Tribunal (NGT) was established in accordance with the National Green Tribunal Act, 2010. NGT is the specialized judicial body, consisting of technical members and judicial members, constituted for adjudicating environmental cases and reducing the burden of litigation in other courts in the country. In matters involving air pollution, anyone seeking relief or compensation for environmental damage concerning issues included in the Air (Prevention and Control of Pollution) Act of 1981 may approach the tribunal. Before the establishment of the NGT, the country’s apex court played a vital role in delivering land-mark decisions concerning air pollution. The objective of the current study is to assess if the involvement of technical experts in the tribunal has improved the redressal mechanism. The judgments were reviewed in SCC online’s case finder and NGT official portal. The methodology involved analyzing cases decided by the NGT for five indicators that signal the use of technical expertise in decision-making. These indicators are (i) scientific/ technical content of the ratio decidendi, (ii) technical investigation of the case directly by NGT, including site visits by its technical experts, (iii) Assessment of technical reports directly by NGT, without the help of external experts (iv) insistence by NGT on studies using latest techniques as part of the investigation (v) Evaluating reversal of NGT verdict following the Supreme Court appeal on technical grounds. In general, this study assesses the role of the scientific experts as decision-makers in the environmental redress process. Reported cases, supported by existing literature show that scientific experts had a significant policy impact, which is crucial in air quality management. A guideline document, similar to the Environmental crime investigation manual of INTERPOL can improve the situation further by helping the investigator choose the suitable approach for a given scenario.  
Analysis of compound flooding in the Tapi River Basin
Authors: Beg Zafar , Gaurav Kumar
Published: February 2023

We coupled a hydrologic model Variable Infiltration Capacity (VIC) with the Hydrologic Engineering Center River Analysis System (HEC-RAS-2D) to model the compound impact of flood drivers in the Tapi River basin, India. Our modelling framework consists of two distinct phases; firstly, we calibrate and validate the VIC simulated daily stream flow of the Tapi River using the data observed at the Sarangkheda gauge (upstream of Ukai Reservoir) during the 2005-2012 and 2013-2016, respectively. Secondly, to simulate the high and low flow events, a separate HEC-RAS 2D model is forced with flood hydrograph (Ukai dam release) and stage hydrograph (Tidal level at Hazira) as upstream and downstream boundary conditions, respectively. We calibrated this hydrodynamic model for the 2012 flood event and validated it for the 2006 and 2014 flood events with the observed discharge and water level at the five gauges (Kakrapar Weir, Ghala, Kathor, Singanpur Weir and Nehru Bridge) located along the Tapi River in the Lower Tapi Basin (LTB). We observed that the VIC simulated daily stream flow accords well with the observed in-situ measurements. The Kling-Gupta and Nash Sutcliffe Efficiency values for calibration are 0.84 and 0.86, while, for validation, the values are 0.78 and 0.71, respectively. Furthermore, the hydrodynamic model analysis indicates satisfactory performance with the Root Mean Square Error (RMSE) for discharge and water levels in the range of 300-325 m3s-1 and 0.12–0.43 m, respectively. Finally, we prepare the flood hazard maps to provide critical insights for effective flood management and to enhance the flood resilience of the flood-prone regions of the LTB.
Helicopter Magnetic Field Surveys for Future Mars Missions
Authors: Mittelholz Anna , Heagy Lindsey , Johnson Catherine L. , Fraeman Abigail A. , Langlais Benoit , Lillis Rob J. , Rapin William
Published: February 2023

The recent successful flight demonstration of the Mars 2020 helicopter, Ingenuity, has opened doors for future Mars mission concepts that exploit modern technology, and promising investigations include low altitude magnetic field surveys.  The martian crustal magnetic field has been studied extensively from orbit and those data sets have allowed global studies of the magnetic field and resulted in a range of models for the crustal magnetic field which however lack short wavelength information that is not resolvable from orbital altitudes. The InSight lander and the Chinese Zhurong missions have recently acquired magnetic measurements of the local field at their respective landing sites. However, to-date no measurements at scales in between those of local surface and global orbital data have been collected.  Such measurements are key to understanding near-surface magnetizations, the processes by which they were acquired, and their interaction with magnetic fields generated above the planet’s surface. Here, we investigate data sets that a future helicopter-based magnetometer might be able to provide.We construct forward models that resemble a range of plausible subsurface geological structures that allow us to experiment with survey design, e.g., the value of multiple measurement tracks horizontally and/or vertically and their trade-offs with regional data coverage. We simulate vector magnetic field data collected by a helicopter for different geological scenarios and aim to recover our model via an inverse problem. Because such inverse problems are inherently non-unique, we investigate several approaches to find solutions, including different types of regularization, as well as modification of the model parameterization.   As one example, we investigate recovery of a magnetization signature associated with a small (~200 m diameter) crater, from a few (e.g., 3) helicopter tracks over the crater.   We show that smooth and sparse inversion solutions result in detection of the signal, with improved localization of the structure in the latter case.  Parameterized solutions improve upon sparse solutions, but require some prior knowledge, or assumption, of the geometry (in this case a magnetized half sphere) of the source.Our investigation allows us to assess the capabilities of helicopter-based magnetic field  studies in addressing some of the fundamental open questions in the field. These kinds of considerations will greatly aid in preparing for and designing future missions,  optimizing their science return and demonstrating their scientific value.
 