bluuebunny/crossref_metadata_2025 huggingface dataset:
Drivers of inner gorge incision in the Fraser Canyon (British Columbia, Canada)
Authors: Seagren Erin , Steelquist Aaron , Carr Julia , Dingle Elizabeth , Larimer Jeff , Wright Morgan , Heathfield Derek , Larsen Isaac , Menounos Brian , Venditti Jeremy
Published: February 2023

Bedrock inner gorges, or narrow and deeply-incised canyons set within broader valleys, are common features in post-glacial landscapes and may reflect the interaction of glacial-fluvial processes. Though widespread, the origins of bedrock inner gorges are enigmatic and have been variably attributed to subglacial meltwater during deglaciation, outburst floods, and subaerial fluvial incision as a response to base level change. It is also unclear if their morphology reflects erosion from a single deglacial period or evolution over multiple glacial-interglacial cycles.

Given widespread inner gorges, quartz-bearing rocks, and a history of multiple glaciations, the Fraser Canyon – a 375-km stretch of the Fraser River in British Columbia (Canada) characterized by alternating bedrock and non-bedrock reaches – is an ideal area to explore the drivers of inner gorge incision. Using topographic analyses to characterize the morphology of these bedrock gorges, we assess incision rates required to form the canyons since deglaciation (~14 – 11.7 ka). Using the morphology (e.g., slope) of glacio-fluvial terraces and channel long profile analyses (e.g., ksn), we evaluate whether inner gorges likely formed through 1) interaction of glacial and fluvial erosion during glaciation, 2) one or more catastrophic outburst floods, or 3) steady subaerial fluvial erosion due to isostatic uplift/base level fall since deglaciation. We conclude by exploring the relative efficacy of these erosional processes and implications for the longevity of fluvial and glacial landscapes.
Revisiting the mechanisms of ENSO response to tropical volcanic eruptions
Authors: Pausata Francesco S.R. , Zhao Yang , Zanchettin Davide , Caballero Rodrigo , Battisti David
Published: February 2023

Large explosive volcanic eruptions can have major impacts on global climate, affecting both radiative balance and inducing interannual-to-decadal dynamical alterations of the atmospheric and ocean circulation. Despite some discrepancies across studies regarding the response of ENSO to volcanism based on paleoclimate data, the majority of ENSO reconstructions  display an El Niño–like warming in the year of eruption, while none display a significant La Niña–like response, Furthermore, there has been an emerging consensus from the numerous coupled General Circulation Model studies investigating the impact of tropical volcanism on ENSO, with the overwhelming majority displaying an El Niño–like warming occurring in the year following the eruption. However, the mechanisms that trigger a change in the ENSO state following volcanic eruptions are still debated. The center of the argument is understanding how volcanism can affect the trade winds along the equatorial Pacific.Here, we shed light on the processes that govern the ENSO response to tropical volcanic eruptions through a series of sensitivity experiments with an Earth System Model where a uniform stratospheric volcanic aerosol loading is imposed over different parts of the tropics. Three tropical mechanisms are tested: the “ocean dynamical thermostat” (ODT); the cooling of the Maritime Continent; and the cooling of tropical northern Africa (NAFR). We find that the NAFR mechanism plays the largest role, while the ODT mechanism is absent in our simulations as La Niña-like rather than El-Niño-like conditions develop following a uniform radiative forcing over the equatorial Pacific.
Lagrangian pathways under the Filchner-Ronne ice shelf and in the Weddell Sea
Authors: Maderich Vladimir , Bezhenar Roman , Brovchenko Igor , Bezhenar Antonina , Dias Fabio Boeira , Uotila Petteri
Published: February 2023

The objective of the study is to construct Lagrangian pathways under the Filchner-Ronne ice shelf (FRIS) and in the Weddell Sea using the data of numerical simulation of currents and Lagrangian numerical methods. The yearly cycled results of modeling for the circulation, temperature, and salinity in the Weddell Sea and the FRIS cavity from the Whole Antarctica Ocean Model (WAOM) were used to run the particle-tracking model (Parcels) for computing Lagrangian particle trajectories. The original version of the Parcels model does not have an option for particle reflection from the solid boundaries including the ice shelf. Therefore, the corresponding kernel was developed in the current study. The Parcels model gives an error in interpolation when it cannot find enough grid nodes around the particle. To avoid these errors, the function of particle recovery was developed. To analyze the variations of movement of the water masses under the FRIS, a set of particles was released in the Ronne Depression near the ice shelf front. Particles were released at two depths: 350 m and 500 m under the sea surface. Particles were released each 4 hr within 365 days. Simulation continued for 20 years of particle movement. The results of Lagrangian analysis generally agreed with schemes based on water mass analysis. The released particles first move southward along the Ronne Trough. The flow then turns to the east reaching the passage between Berkner Island and Henry Rise after 3 years. After 10 years, the flow of transformed water reaches the Filchner Trough through which water flows out to the shelf of the southern part of the Weddell Sea. Over time, the particles penetrate into all parts of the cavity. Some of the particles cross the Ronne Shelf front, and then they are carried away by currents on the Weddell Sea shelf. In 20 years, almost the same number of particles left the cavity through the Ronne ice front (43%) and the Filchner ice front (37%) whereas the rest of the particles (20%) remained under FRIS.
Effects of denitrification on the distributions of trace gas abundances in the polar regions: Comparison of the Whole Atmosphere Community Climate Model with observations
Authors: Kinnison Douglas , Weimer Michael , Wilka Catherine , Solomon Susan
Published: February 2023

Polar stratospheric clouds (PSCs) play a key role in the polar chemistry of the stratosphere. Nitric acid trihydrate (NAT) particles have been shown to lead to denitrification of the lower stratosphere. While the existence of large NAT particles (NAT "rocks") has been verified by many measurements, especially in the Northern Hemisphere (NH), most current chemistry-climate models use simplified parametrizations, often based on evaluations in the Southern Hemisphere where the polar vortex is stable enough that accounting for NAT rocks is not as important as in the NH. Here, we evaluate the probability density functions of various gaseous species in the polar vortex using one such model, the Whole Atmosphere Community Climate Model (WACCM), and compare these with measurements by the Michelson Interferometer for Passive Atmospheric Sounding onboard the Environmental Satellite (MIPAS/Envisat) and two ozonesonde stations for a range of years and in both hemispheres. Using the maximum difference between the distributions of MIPAS and WACCM as a measure of coherence, we find better agreement for HNO3 when reducing the NAT number density from the standard value of 1 x 10−2 cm-3 used in this model to 5 × 10−4 cm−3 for almost all spring seasons during the MIPAS period in both hemispheres. The distributions of ClONO2 and O3 are not greatly affected by the choice of NAT density. The average difference of WACCM to ozonesondes supports the need to reduce the NAT number density in the model. Therefore, this study suggests using a NAT number density of 5 × 10−4 cm−3 for future simulations with WACCM. 
A new born theory for the genesis and dynamics of Madden–Julian oscillation-like structure
Authors: Rostami Masoud , Zhao Bowen , Petri Stefan
Published: February 2023

By means of a new multilayer pseudo-spectral moist-convective thermal rotating shallow-water (mcTRSW) model in a full sphere, we present a possible equatorial adjustment beyond Gill’s mechanism for the genesis and dynamics of the Madden–Julian oscillation (MJO). According to this theory, an eastward-propagating MJO-like structure can be generated in a self-sustained and self-propelled manner due to nonlinear relaxation (adjustment) of a large-scale positive buoyancy anomaly, depressed anomaly, or a combination of these, as soon as this anomaly reaches a critical threshold in the presence of moist convection at the Equator. This MJO-like episode possesses a convectively coupled “hybrid structure” that consists of a “quasi-equatorial modon” with an enhanced vortex pair and a convectively coupled baroclinic Kelvin wave (BKW), with greater phase speed than that of dipolar structure on an intraseasonal time-scale. Interaction of the BKW, after circumnavigating the entire Equator, with a new large-scale buoyancy anomaly may contribute to excitation of a recurrent generation of the next cycle of MJO-like structure. Overall, the generated “hybrid structure” captures a few of the crudest features of the MJO, includingits quadrupolar structure, convective activity, condensation patterns, vorticity field, phase speed, and westerly and easterly inflows in the lower and upper troposphere. Although moisture-fed convection is a necessary condition for the “hybrid structure” to be excited and maintained in the proposed theory in this study, it is fundamentally different from moisture-mode theories, because the barotropic equatorial modon and BKW also exist in “dry” environments, while there are no similar “dry” dynamical basic structures in moisture-mode theories. The proposed theory can therefore be a possible mechanism to explain the genesis and backbone structure of the MJO and to converge some theories that previously seemed divergent (DOI:10.1002/qj.4388). 
Moisture with Gusto: towards moist shallow water test cases using the Gusto dynamical core toolkit
Authors: Hartney Nell , Shipton Jemma , Bendall Thomas
Published: February 2023

The shallow water equations are widely used in the development of weather and climate models, being computationally cheap while still retaining many pertinent features of atmospheric dynamics. The usual shallow water equations, however, model a ‘dry’ atmosphere and so neglect moist processes and moisture effects. Including moisture in the shallow water system offers a framework in which to develop more challenging test cases for parallel time-stepping schemes, arising through numerical complexities that moisture introduces and relevant because of changing trends in supercomputer architectures necessitating interest in parallel-in-time. This talk will discuss the implementation of moist shallow water models in the dynamical core toolkit Gusto, which mirrors the compatible finite element approach being taken in the next-generation UK Met Office model. We will highlight the advantages Gusto offers for rapid prototyping and flexible implementation of different moist shallow water models and describe progress towards running moist shallow water tests cases (both from the literature and newly-devised for this purpose) in Gusto.
Comparison of a reduced-complexity model to a full model for storm surge predictions
Authors: Veeramony Jay , van Ormondt Maarten , Kacey Edwards , Allison Penko
Published: February 2023

The ability to anticipate the changes in water levels, waves and current velocities associated with storms is critical to determining the storm damages including morphological changes and coastal structure interaction. Typically, storm surge forecasts are generated using complex modeling systems such as ADCIRC, COAWST or Delft3D which solve the Navier-Stokes equations driven by the wind and wave forcing. These models often take time and effort to set up and needs significant computational resource to produce results at the required resolutions. The advantages are obvious – all the relevant physics are represented with a high degree of accuracy in these models. However, the accuracy of the models is often overshadowed by the uncertainties in the forecast of the storm itself. To capture the effects of these uncertainties, we need to resort to ensemble simulations, which brings us to the main disadvantage of these systems – they require significant computational effort to execute even one of the scenarios. Thus, to get timely information about the surge, it is necessary to either reduce the number of members in the ensemble or reduce the resolution at which the model simulates the event, thereby reducing the confidence in the model results. Here we investigate an alternative approach to storm surge predictions – use a reduced complexity model to compute the surge and compare the results to a full model as well as to data to assess the effectiveness of the models. As a case study, we will compare the two approaches using the forecasts from Hurricane Ida (2021) which impacted Louisiana. We will use the Delft3D FM system as representative of the full physics model and compare the results to that produced by SFINCS, which is a reduced complexity model. Comparisons of water levels at available NOAA tide stations are used to validate the model and quantify errors in the system. Wave statistics are compared against available buoys.
Assessment of Saildrone Wind Measurements in Tropical Cyclones using Microwave Satellite Sensors
Authors: Ricciardulli Lucrezia , Foltz Gregory , Manaster Andrew , Meissner Thomas
Published: February 2023

In-situ measurements of extreme winds within hurricanes are challenging and scarce at the global level. They are mostly provided by risky reconnaissance flights, most often in the tropical North Atlantic. In 2021, a novel NOAA project deployed 5 Saildrones (SDs) to monitor the tropical Atlantic storm-track areas. One of these missions, SD-1045, crossed Hurricane Sam (Cat. 4) on September 30, 2021, providing an unprecedented view of ocean surface conditions within a major hurricane, reporting surface winds as high as about 40 m/s.  New SD missions for the 2022 Atlantic hurricane season were also able to intercept the tracks of Hurricane Fiona and Ian.Here we present a comprehensive analysis and interpretation of the Saildrone ocean surface wind measurements in these hurricanes, using the following datasets for comparison: NDBC buoys in the path of the storms, microwave (MW) radiometer wind retrievals and tropical cyclone (TC) winds from SMAP and AMSR2, wind retrievals from the ASCAT scatterometers, from the high-resolution Synthetic Aperture Radars, and the HWRF model winds. The methodology for adjusting the SD wind measurements to a 10m reference height and to the different spatial scales of satellite observations will be described in detail. In this presentation, we will address the consistency of the SD observations with the satellite data at all wind speed regimes, with special focus at extreme winds.This study can serve as foundation for planning and monitoring the quality of wind measurements from SD missions in the tropics and extra-tropics using satellite data.  Additionally, if properly interpreted, future SD missions can provide a unique and much needed reference source of calibration/validation for satellite observations at wind speeds above 20 m/s, for which buoy data are less accurate.
From hot air to environmental injustice: end to end event attribution
Authors: Wehner Michael , Smiley Kevin , Sampson Christopher
Published: February 2023

The human influence on many classes of extreme weather events has been made very clear by extreme weather event attribution studies. However, this is only the first step to quantify the human influence on the actual impacts from these events. Using Hurricane Harvey as a storyline example, we illustrate the causal chain from increased temperatures to increased precipitation to increased flooding to increased structural damages. Detailed geographical information about the effect of climate change on the flood leads to an attribution statement about damages and is combined with census data revealing profound disparities across socioeconomic groups. We leave the listener with rhetorical questions: Can one quantify environmental injustice? If so, can an end to end attribution statement about climate change induced loss and damages provide a defensible claim for reparations?
Mineralogical and isotopic studies in the Gol-Cheshmeh copper deposit, NE Iran
Authors: Bakhshandeh Behrooz , Entezari Harsini Azam , Masoumi Rahim , Bakhshandeh GharehTapeh Farahnaz , Babaei Asgar
Published: February 2023

The studied area is situated as a narrow strip NE Iran and belongs to Central Iran structural zone and also the Kavir-Sabzevar magmatic zone which is related to continental arc subduction zone of NE Iran. The mineralization is hosted in Eocene andesite-basalt, trachyandesite, andesite, and monzodiorite with high potassic shoshonite affinities that have undergone propylitic alteration. The disseminated copper oxide and sulfide mineralization occurs in the form of stratabound, vein-veinlet and open space filling, resulted from replacement of volcanic units simultaneously with sericitization and silicification of the host rocks. Two stages of mineralization have been recognized, namely a hydrothermal stage and supergene enrichment stage. Chalcocite, covellite, chalcopyrite, bornite, digenite, and tetrahedrite are the main hypogene minerals, that were altered during the supergene enrichment into bornite, secondary chalcocite, and Cu-carbonates. The range of δ34S values in primary chalcocites (-7.7‰-9.3‰) and the δ34S H2S (-3.5‰-5.2‰) indicate that the source of sulfur in ore forming fluids was most likely sedimentary. The hypogene ore minerals are enriched in Ag, As, Ba, Sr, Fe, Mn, Zn, and Ce compared to their supergene counterparts. The enrichment of Cu took place during the supergene stage. The study of hornblende pyroxene olivine andesite basaltic zircons, show the average age of 5.47 ± 0.22 my for this unit. Also, based on the study of zircons, the average age of the pyroxene hornblende monzodiorite is 2.44 ± 0.79 my.

Key words: Gol-Cheshmeh; Manto-type; Cu mineralization; sulfur isotopes; Nd-Sr isotopes; NE Iran.

 
Nonlinear intensification of monsoon low pressure systems by the BSISO
Authors: Hunt Kieran , Turner Andrew
Published: February 2023

More than half of the rainfall brought to the Indian subcontinent by the summer monsoon is associated with low-pressure systems (LPSs). Yet their relationship with the Boreal Summer Intraseasonal Oscillation (BSISO) – the dominant intraseasonal forcing on the monsoon – is only superficially understood. Using reanalysis data, we explore the relationship between the BSISO and LPS intensity, propagation, and precipitation, and associated underlying mechanisms.The BSISO has a large impact on mean monsoon vorticity and rainfall as it moves northward – maximising both in phases 2-3 over southern India and phases 5-6 over northern India – but a much weaker relationship with total column water vapour. We present evidence that LPS genesis also preferentially follows these phases of the BSISO.We identify significant relationships between BSISO phase and LPS precipitation and propagation: for example, during BSISO phase 5, LPSs over north India produce 51% heavier rainfall and propagate northwestward 20% more quickly.Using a combination of moisture flux linearisation and quasigeostrophic theory, we show that these relationships are driven by changes to the underlying dynamics, rather than the moisture content or thermodynamic structure, of the monsoon.Using the example of LPSs over northern India during BSISO phase 5, we show that the vertical structure of anomalous vorticity can be split into contributions from the BSISO background circulation and the nonlinear response of the LPS to anomalous BSISO circulation. Complementary hypotheses emerge about the source of this nonlinear vorticity response: nonlinear frictional convergence and secondary barotropic growth. We show that both are important. The BSISO imparts greater meridional shear on the background state, supporting LPS intensification. The BSISO background and nonlinear LPS response both contribute significantly to anomalous boundary layer convergence, and we show through vortex budget arguments that the former supports additional LPS intensification in boundary layer while the latter supports faster westward propagation.This work therefore yields important insights into the scale interactions controlling one of the dominant synoptic systems contributing to rainfall during the monsoon.
Simulating atmospheric dust and its radiative impact with a global variable-resolution model
Authors: Zhao Chun , Feng Jiawang , Du Qiuyan , Xu Mingyue , Gu Jun , Hu Zhiyuan
Published: February 2023

In this study, a global variable-resolution modeling framework of atmospheric dust and its radiative feedback is introduced and evaluated. In this model, atmospheric dust is simulated simultaneously with the meteorological fields, and dust-radiation interaction is included. Five configurations of global mesh with the refinement at different resolutions and over different regions of interest are used to explore the impacts of regional refinement on modeling dust lifecycle at regional and global scales. The model produces reasonably the overall magnitudes and spatial variabilities of global dust metrics such as surface mass concentration, total deposition, AOD, and radiative forcing compared to observations and previous modeling results. Two global variable-resolution simulations with mesh refinement over major deserts of North Africa (V16km-NA) and East Asia (V16km-EA) simulates less dust emissions and smaller dry deposition rate inside the refined regions due to the weakend near-surface wind speed caused by better resolved topographic complexity at higher resolution. Dust mass loading over North Africa is close to each other between V16km-NA and U120km, while over East Asia, V16km-EA simulates higher dust mass loading. Over the non-refined areas with the same resolution, the difference between global variable-resolution and uniform-resolution experiments also exist, which is partly related to their difference in dynamic time-step and the coefficient for horizontal diffusion. Refinement at convection-permitting resolution around the Tibet Plateau (TP) leads to significantly different dust and precipitation around the TP against coarse resolution, which implies that dust-precipitation interaction over this area deserves further investigation with this  global variable-resolution modeling framework in future. 
Improving single particle ICP-TOFMS using a desolvation sample introduction system and collision cell technology
Authors: Lee Geunwoo , Erhardt Tobias , Hendriks Lyndsey , Tanner Martin , Delmonte Barbara , Fischer Hubertus
Published: February 2023

Inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) is increasingly used in various disciplines, especially for the characterization of single particles, because it allows truly simultaneous determination of isotopes over full mass range without sacrificing analytical sensitivity (Baalousha et al., 2021; Erhardt et al., 2019; Goodman et al., 2022). In particular, the extremely high time resolution of TOFMS allows us to detect individual mineral dust particles in the water stream obtained from Continuous Flow Analysis of Greenland Ice cores. Even though collision cell technology (CCT) and high-sensitivity sample introduction have been applied to the ICP-MS systems to overcome analytical limitations in spectral interferences and sensitivity (Burger et al., 2019; Lin et al., 2019), the impact of CCT and high-sensitivity desolvation sample introduction on analysis of single particles, unlikely to bulk analysis, are still relatively poorly understood. We investigated the effects of CCT and high-sensitivity desolvation sample introduction (individually and in combination) on the capability of single particle (sp) ICP-TOFMS including sensitivity and transport/transmission efficiency. To do so, we systemically investigated differences in the sensitivity of total Au, the transport efficiency of Au nano particles as well as the signal amplitude above the background of these nano particles. Application of the desolvation unit without CCT led to a significant improvement of the transport efficiency (number of particles introduced into the plasma) by a factor of about 5 but to a reduction of sensitivity (counts per particle) by about 30 percent. When CCT was used for sp-ICP-TOFMS without the high-sensitivity sample introduction system, the sensitivity for gold ion in particle signals increased by only about six percent. This is similar to the sensitivity improvement for gold ions in dissolved background signals from the ion focusing effect after the collision cell. However, when CCT was used in combination with the high-sensitivity sample introduction system, the sensitivity for gold ion in particle signals increased by another up to about 33 percent compared to the desolvation system without CCT. This could be because the collisional ion focusing is more effective under the high sample transport condition of the high-sensitivity sample introduction system. In conclusion, the high-sensitivity sample introduction system increased the number of detected particles by about 5 times while drying the sample and applying CCT enhanced the sensitivity of analyte ions in the ion optics of sp-ICP-TOFMS by about a third for gold particle signals and a factor of 2 for multi-elemental dissolved background signals. These enhancements will help us to analyze trace isotopes in ice core mineral dust particle analysis and to characterize the chemical composition of detected particles by sp-ICP-TOFMS.
The global distribution and trends of ozone health-based metrics: New results from the TOAR-II Database
Authors: Cooper Owen , Chang Kai-Lan , Schröder Sabine , Selke Niklas , West J. Jason , Serre Marc
Published: February 2023

The first phase of the Tropospheric Ozone Assessment Report (TOAR-I), an activity of the International Global Atmospheric Chemistry Project (IGAC), provided the first comprehensive view of surface ozone’s global distribution and trends, based on all available surface ozone observations.  TOAR-I focused on a present-day period of 2010-2014, and calculated trends for a range of periods, but primarily focused on the most recent years of 2000-2014, plus long-term trends from the 1970s/1980s through 2014.  Subsequent studies of ozone trends using data after the TOAR-I cut-off of 2014, have shown a wide range of trends, both positive and negative, at monitoring sites around the world.  To keep up with the rapid changes of ozone at urban, rural and remote locations this study provides current world-wide ozone trends using observations through 2021, archived in the newly updated TOAR-II Database of Surface Observations.  Focus is placed on two ozone metrics relevant to human health impacts:  1) the annual peak of the 6-month running mean of maximum daily 8-hour average ozone; this metric is used by Global Burden of Disease (GBD) to estimate mortality due to long-term ozone exposure; 2) the number of days per year that exceed 70 ppbv, based on the maximum daily 8-hour average ozone value; this value corresponds to the primary U.S. National Ambient Air Quality Standards for ozone and is relevant to short-term ozone exposure.  Global maps will indicate the regions of the world where the potential for ozone impacts on human health are greatest (and least), and will show regions where ozone air quality is either improving or degrading.  Despite our effort to use all available surface ozone observations, large data gaps exist across many regions of the world, especially in developing nations, and GBD maps generated by data fusion will be used to identify, and to estimate ozone levels in the data-poor regions. 
The Non-Linearity of Cascades and Feedbacks Between The Biosphere and Society: Risk Ethics for a Climate Change Technofix
Authors: Wodak Joshua
Published: February 2023

In light of the hysteresis and acceleration of the climate crisis, climate overshoot has only recently been acknowledged as inevitable. As the IPCC belatedly reports, current pledges are not even remotely on track to limit global warming to 1.5°C above pre-industrial levels (Anderson 2015, IPCC 2018). Further, no amount of future emissions reductions can suffice to avert climate overshoot. Hence, this presentation critically analyses the proposition that a climate change technofix – namely Negative Emission Technologies (NETs) – is the only potentially efficacious means to avert runaway climate change (Carton 2020, Reynolds 2015).However, not only is the efficacy of NETs to reduce sufficient greenhouse gas concentrations highly dubious, but any such technofix requires gambling on a host of unknown unknowns – namely, the inexorable complexity of the Earth System, coupled with planetary-scale interventions in the crisis. Therein, this presentation explores the linkages between extreme climate and societal dynamics surrounding risk, offering a theoretical study from the fields of social sciences and humanities as to the non-linearity of cascades and feedbacks between the biosphere and society.To do so, I put forth a critique of how normative ethics remains anchored in rigid positions of anachronistic risk aversion, given how any attempted climate technofix entails unprecedented realms of risk and uncertainty. Using the frameworks of the Environmental Humanities, and Science & Technology Studies, I critically engage with the risk ethics of imminent climate overshoot, in relation to the interventionist gambles proposed by NETs through Synthetic Biology and Climate Engineering. Given the scale of the unknown unknowns unleashed by the Anthropocene, I present gambling as the most apt analogy for both the absurdity (and denied imminence) of the existential predicament, as well as the sheer improbability that any technofix can be invented in a sufficiently short time and implemented on a sufficiently large scale.Given the profound social, cultural and ethical dimensions that this entails, discussion will include an overview of outreach activities I have undertaken as a Chief Investigator at the Australian Research Council Centre for Excellence in Synthetic Biology, including the At Risk in the Climate Crisis symposium and podcast series that I co-produced in 2021-22. Overall, in the context of the rapidly diminishing prospect for any efficacious environmental action, the presentation contemplates the unthinkable questions that our current situation demands we ask, and perhaps even try to answer.
Potential value of combining CNN, GEDI and multi-source remote sensing data to improve the estimate of aboveground forest carbon storage in northeast China
Authors: Lv Guanting
Published: February 2023

Quantifying forest biomass carbon (C) stock is critical for determining the regional carbon balance, but, a lack of both field observations spanning large climatic gradients and proper upscaling methods which take the spatial pattern into account, means there is little knowledge regarding forest C stock at high spatial resolutions. Here, we address this problem by combining a deep convolutional neural network (CNN) algorithm with in situ measurements, Global Ecosystem Dynamics Investigation (GEDI) observations, and Landsat and PALSAR-2 images to develop a new, spatially explicit estimate of forest aboveground carbon density (ACD) circa 2020 at a 30 m spatial resolution for northeast China, home to nearly one-third of China’s forested area. The result yields a high coefficient of determination (R2) of 0.83 and a relatively low root mean squared error (RMSE) of 5.28 MgC ha-1, and is superior to traditional pixel-based and in situ based methods. Through linking in situ measurements with nearly 0.13 million GEDI observations, we obtained important samples across spatially variable environmental conditions, and in remote and rugged regions (when increasing the number of GEDI samples, RMSE decreased by 73.5%). CNN was able to extract important spatial patterns and performed well in capturing the spatial variation of forest carbon density. We also propose a CNN-based perturbation method to rank variable importance, which shows that the distribution of forest C storage is mainly determined by precipitation and forest age. Based on the proposed method, the local forest aboveground biomass C stock is estimated to be 3.52 ± 0.10 PgC, with an age-related forest aboveground biomass C sink of 7.94 TgC year-1 before 2060. Terrestrial ecosystem models generally underestimate the regional C stock, partially because of biases in forest age simulations. The study highlights the importance of using deep learning methods to gain further process understanding of forest carbon dynamics under climate change.
Integration optimal irrigation schedule with biochar applications can economize water and maintain yield in cotton&sugarbeet monoculture and intercropping
Authors: Wang Xiaofang , Li Yi , Biswas Asim , Sang Honghui , Feng Hao , Yu Qiang , He Jianqiang
Published: February 2023

Arid areas in the world are pressed to grow more crop per drop of water to meet food security. Soil salinity, an unavoidable challenges in arid areas is exacerbating the situations. Management practices such as use of salt tolerant crops including cotton and sugarbeet, plastic mulched drip irrigation, intercropping and application of biochar are often recommended and adopted in many arid areas including Xinjiang, one of the northwestern provinces in China with arid climate. Studying the effectiveness of these management practices, however, are often difficult, costly and time-consuming. For example. difficulty in obtaining information on the dynamics of soil water and salt restricts comprehensive understanding on the effectiveness of soil amendments such as biochar’s impact in increasing yield and optimizing irrigation schedules, while numerical simulations show promise. The objectives of this study were to simulate the dynamics of soil water, salt and root water update (RWU) of cotton and sugarbeet in monoculture and intercropping systems in an arid climatic condition to minimize soil water loss through optimal irrigation under plastic mulched drip irrigation systems. A 3-year field experimental results from a cotton and sugarbeet monoculture and intercropping systems from Xinjiang, China was used to calibrate and validate HYDRUS-2D model. Soil water and salt dynamics were measured at fields with biochar applied at 0 t ha-1 (CK), 10 t ha-1 (B10) and 25 t ha-1 (B25) and the soil hydraulic and solute transport parameters were optimized in HYDRUS-2D, that was calibrated and validated to satisfy the requirements of minimum simulation accuracy (R2>0.75, RRMSE<14.2% and NSE>0.73). Simulation showed that the application of biochar increased storage of soil water and salt. The RWU ranked as B10> B25> CK, which was consistent with soil water storage (SWS) and yield. Soil water balance components indicated that the application of biochar at 10 t ha-1 increased RWU, reduced Ea and water drainage. to the results were helpful to understand the mechanisms of biochar and intercropping in increasing crop yield. The adjusted irrigation schedule can save up to 50 mm of irrigation water and 50 Yuan costs per hectare for farmers. The research provides a reference for agricultural production in arid and semi-arid areas.
The lifecycle of snow in the Sierra Nevada USA: from snowfall to snowmelt and effects on endangered bighorn sheep
Authors: Qian Yun , Huang Huilin , He Cenlin , Bair Ned , Rittger Karl
Published: February 2023

Snow is a valuable resource in California. Snow from the Sierra Nevada sustains a diverse ecosystem and provides 3/4 of California’s Agricultural water supply. Because of its importance in water supply and global climate, snow accumulation, melt, and sublimation were ranked as the most important objectives in the 2017 Decadal Survey. This study employs a fully coupled meteorology‐chemistry‐snow model to investigate the impacts of both global warming and light‐absorbing particles (LAPs) on snow in the Sierra Nevada. Using self-organizing map (SOM) analysis with dust deposition and flux data from model and observations, we identify four typical dust transport patterns across the Sierra Nevada, associated with the mesoscale winds, Sierra barrier jet, North Pacific High, and long-range cross-Pacific westerlies, respectively. The satellite retrievals and model results show that LAPs in snow reduce snow albedo by 0.013 (0–0.045) in the Sierra Nevada during the ablation season (April-July), producing a midday mean radiative forcing of 4.5 W m−2 which increases to 15–22 W m−2 in July. LAPs in snow accelerate snow aging processes and reduce snow cover fraction, which doubles the albedo change and radiative forcing caused by LAPs. The impurity-induced snow darkening effects decrease snow water equivalent and snow depth by 20 and 70 mm in June in the Sierra Nevada bighorn sheep habitat. The earlier snowmelt reduces root-zone soil water content by 20%, deteriorating the forage productivity and playing a negative role in the survival of bighorn sheep. We also conduct the simulations using our coupled regional model to compare the impact of global warming vs. LAPs on snow melting by adopting the pseudo-global warming (PGW) approach to generate projections of future meteorological forcing. These results will be used to examine snow effects on endangered Sierra Nevada bighorn sheep and how a future climate might modify habitat and behavior.
A numerical methodology for rupture propagation at bi-material interfaces with rate- and state-dependent friction
Authors: Gupta Avinash , Kunnath Ranjith
Published: February 2023

Frictional sliding at bi-material interfaces (when contacting bodies possess different elastic properties) is important in context of earthquake dynamics. Dissimilarity in elastic materials across the interface give rises to complex rupture propagation phenomena and instabilities, compared to the case when the material is similar across the interface. This is due to the coupling between the normal stress and interfacial slip, which is absent in the homogenous case. In the literature, various numerical schemes have been proposed but still many aspects of bi-material ruptures are not well-understood such as the rupture mode, velocity selection and stability. The present work proposes a new numerical scheme to study frictional rupture at a bi-material interface governed by a rate- and state-dependent friction law. It uses a spectral form of the boundary integral equation method (BIEM) as derived in Ranjith (2015, 2022), to evaluate the field quantities at the interface. The BIEM approach computes elastodynamic convolution of traction over its temporal history at the interface only, without need to calculate in regions away from interface, making it numerically efficient, compared to other conventional approaches. In prior work, an alternative spectral form of BIEM was used by Breitenfeld and Geubelle (1998) for 2D in-plane elasticity and Morrissey and Geubelle (1997) for 2D antiplane elasticity. In their approach, time-convolution is performed of the displacement history at the interface. An advantage of Ranjith’s approach is that the convolution kernels for a bi-material interface can be expressed in closed form, whereas Breitenfeld and Geubelle (1998) had to obtain their convolution kernels numerically. Conversion between real space and spectral domain is done by the Fast Fourier Transform (FFT). Rupture propagation is studied for both in-plane and antiplane frictional sliding at a bi-material interface by coupling the BIEM with a rate- and state-dependent friction law. Such a friction law is known to be suitable for a bi-material interface because it gives rise to well-posed problems (Rice et al., 2001). In earlier studies, an alternative numerical scheme for rate- and state-dependent friction was proposed by Lapusta et al. (2001) to study earthquake sequences on a fault. The disadvantage of their approach is that convolution kernels need to be evaluated multiple times for higher order accuracy. In the present work, a simpler numerical scheme is proposed for bi-material interfaces following a rate- and state-dependent friction law which is computationally more efficient.
Gravitational raft tectonics in the Tumbes-Guayaquil forearc basin, Northern Andes (North Peru-South Ecuador)
Authors: Peuzin Andréa , Saillard Marianne , Espurt Nicolas , Michaud François , Bulois Cédric , Régnier Marc , Calderon Ysabel
Published: February 2023

Understanding the dynamics of forearc basins is a challenge to improve knowledge of their influence on subduction zone earthquakes and tsunamis. The structural architecture of the Tumbes and Guayaquil forearc depocenters in the Northern Andes is revealed by subsurface data and the construction of serial cross-sections. Seismic reflection profiles and well data reveal that the overall forearc depocenters by widespread gravitational raft tectonics instabilities. These instabilities occurred principally during the Late Neogene to Quaternary period. We emphasize kilometric-scale upper listric normal fault dip regionally basinward paired with downdip thrust wedge. These structures branch downward on a regional décollement level developed in the upper Oligocene ductile shales above subduction zone. The development of this tectonic style appears to be significantly controlled by the coeval of tectonics, high sedimentation rate in the basin and pore pressures processes. Our findings are original enough as these kinds of instabilities are much more often observed in passive margins. Finally, the large active movements of sedimentary masses could also be triggered by seismicity and could generate potential tsunamis that could reach the neighboring coastal zone, including the Guayaquil city.
Stomatal conductance invalidated not very far from boiling
Authors: Kowalski Andrew , Pérez-Priego Óscar
Published: February 2023

Limits to the validity for the stomatal conductance (gs) model of leaf gas exchanges, including CO2 gain for photosynthesis and water loss by transpiration, become evident when applying the laws of physics to the case of evaporation at the boiling point (BP). Very far from the BP, water vapor is a trace gas whose direct influence is negligible, both on air composition and dynamics; the gs paradigm is valid under such conditions. At or very near the BP, however, Dalton's law says that water vapor crowds out dry air species and thereby starves photosynthesis for CO2, and Newton's laws define gas transport as having a non-diffusive nature that is visible in the form of a steam jet. Proximity to the BP thus reduces the water-use efficiency both by impeding the ingress of CO2 and enhancing the egress of water vapor, versus the classical diffusion-only assumption of plant physiology. A derivation from first principles shows that the fraction of vapor transport that is non-diffusive is determined by water vapor's mass fraction, or specific humidity (q). Thus q is a useful measure of proximity to the BP, and ranges from <1%  (very far from the BP) in temperate environments where gs is valid, to ~100% very near the BP where gs is meaningless. Importantly in the context of global warming, with increasing frequency and intensity of heat waves, gs fails to accurately describe plant functioning for conditions that are not very far from the BP. These include very high temperatures and/or low ambient pressure (sub-stomatal q ~ 5-10%), situations that require amendment of the gs paradigm to account for the effects of non-diffusive transport.This work was supported by the projects PID2020-117825GB-C21 (INTEGRATYON3), B-RNM-60-UGR20 (OLEAGEIs) and P18-RT-3629 (ICAERSA) including European Union ERDF funds.
Influence of mixed air pollution on surface micro-meteorological characteristics in autumn and winter in Nanjing area
Authors: Wang Jiaze , Ling Xiaolu , Zhu Xinsheng , Guo Weidong , Zou Jun , Sun Jianning
Published: February 2023

Abstract: This work used the Multi-element observation data from the Station for Observing Regional Processes of the Earth System (SORPES) from November 27 to December 3, 2018. It quantitatively analyzed the influence of mixed air pollution conditions on the surface micrometeorological elements and energy balance characteristics under the combined effects of long-distance sand and dust and local emission pollution. On this basis, the response characteristics of surface meteorological elements and energy distribution under different pollution conditions in autumn and winter in Nanjing are compared by synthetic analysis. The results showed that the daytime temperature on polluted days was about 1°C lower than that on clean days, and the night temperature was about 2°C higher. Both downward/upward shortwave radiation flux decreased on polluted days, and the long-wave radiation flux at night increased. On clean days, the net radiation budget during the day was 45.6% higher than that of polluted days and the surface sensible heat flux was 75.5% higher than that of polluted days. The average Bowen ratio at night on polluted days was higher than that on clean days, indicating that the nighttime sensible heat exchange was stronger. The results help to deeply understand the influence process and mechanism of air pollution from different sources and different properties on surface energy balance and local meteorological elements in the urban agglomerations of the Yangtze River Delta, and the results also provide a verification basis for the interaction between air pollution and meteorological conditions, air quality prediction and corresponding countermeasures.
Study on the influence of seabed scour on monopile stability of offshore wind power by discrete element method
Authors: Lo Chia-Ming , Lai Yu-Sen , Ma Kai-Chin
Published: February 2023

At present, the construction technology of offshore wind power of Taiwan is mostly based on foreign case experience and related design standards. However, the long-term scour effect of the Taiwan current will take away the soil around the pile foundation with the current, thus reducing the embedding depth of the foundation and reducing the stability of the foundation. In addition to being affected by loads such as wind and waves, the offshore wind power foundation is also the key to the overall design of the interaction between the seabed soil and the offshore wind power foundation. Therefore, this study adopts the method of discrete element method coupled with fluid mechanics to deeply explore the pore water pressure and stress changes inside the seabed soil during the seabed scour process around the offshore wind power foundation, and also explores the seabed under different scour mechanism scenarios for offshore wind power foundations. The results of this study show that the sand density of the seabed has a significant impact on the development of the scouring pit. The greater the sand density, the smaller the scouring depth, and the horizontal and vertical development of the scouring pit will also be reduced. the higher the sand density of the seabed, the smaller the lateral displacement of the single pile foundation affected by the erosion effect, which means the higher the lateral bearing capacity that the seabed sand can provide to the monopile foundation.Key words: scour effect, the offshore wind power foundation, discrete element method, scour process; monopile.