bluuebunny/crossref_metadata_2025 huggingface dataset:
Swell and thunder : infrasound signatures of Mediterranean hurricanes
Authors: Listowski Constantino , Forestier Edouard , Dafis Stavros , Farges Thomas , De Carlo Marine , Grimaldi Florian , Le Pichon Alexis , Vergoz Julien , Heinrich Philippe , Claud Chantal
Published: February 2023

Infrasound detections of Mediterranean cyclones known as medicanes (for « Mediterranean hurricanes ») are demonstrated in low- and high- frequency ranges, respectively. We summarize the main findings of a recently published study [1]. We use data from the infrasound station IS48 of the International Monitoring System, in Tunisia, to investigate the infrasound signatures of these meso-cyclones, using a multi-channel correlation algorithm. We discuss cases of detections and non-detections, based on the state of the middle atmosphere and of the wind noise measured at the station. Detections and likely sources are discussed in light of other datasets, comprising satellite observations of deep convection [2] and cloud-to-ground lightning detections from a ground-based network. Detections of infrasound emitted by the cyclone-related swell are modelled using a microbarom source model [3] and are in agreement with observations, comforting the identification of the lower frequency sources. This multi-technology and modelling approach allows to discuss the various sources at plat that may contribute to the monitoring of such extreme meteorological events.[1] Listowski, C.; Forestier, E.; Dafis, S.; Farges, T.; De Carlo, M.; Grimaldi, F.; Le Pichon, A.; Vergoz, J.; Heinrich, P.; Claud, C. Remote Monitoring of Mediterranean Hurricanes Using Infrasound. Remote Sens. 2022, 14, 6162. https://doi.org/10.3390/rs14236162[2] Dafis, S.; Claud, C.; Kotroni, V.; Lagouvardos, K.; Rysman, J. Insights into the convective evolution of Mediterranean tropical-like cyclones. Q. J. R. Meteorol. Soc. 2020, 146, 4147–4169.[3] De Carlo, M.; Accensi, M.; Ardhuin, F.; Le Pichon, A. ARROW (AtmospheRic InfRasound by Ocean Waves): A new real-time product for global ambient noise monitoring. In Proceedings of the EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022 
ARCLIM: bioclimatic atlas of the terrestrial Arctic
Authors: Rantanen Mika , Kämäräinen Matti , Niittynen Pekka , Phoenix Gareth K , Lenoir Jonathan , Maclean Ilya , Luoto Miska , Aalto Juha
Published: February 2023

The warming of the Arctic and its consequences for the global climate system have become one of the strongest manifestations of human-induced climate change. Over the four decades, the Arctic has warmed three to four times faster than globally. In addition to the long-term trend in average temperatures, extreme weather events are becoming increasingly frequent causing disturbances to the Arctic terrestrial ecosystems. Many existing datasets primarily concentrate on seasonal precipitation and temperature at coarse spatial (10-100 km) and temporal (30-year average climatologies) resolutions forming the basis of current understanding of how Arctic ecosystems will respond to climate change. For this reason, the conventional datasets likely leave out many ecologically significant aspects of the Arctic climate relevant for biological or biogeochemical processes. For instance, snow cover duration, rain-on-snow events, or extreme wind events are known to be important variables for Arctic ecology that may not be adequately represented by the more widely used climate statistics.Here, we introduce a new dataset of bioclimatic indices relevant for investigating the changes of Arctic terrestrial ecosystems. The dataset, called ARCLIM, consists of several climate and event-type indices for the northern high-latitude land areas. The indices are calculated from the hourly ERA5-Land reanalysis data for 1950-2021 in a spatial grid of 0.1 degree (~9 km) resolution. We provide the indices in three subsets: (1) the annual values during 1950-2021; (2) the average conditions for the 1991-2020 climatology; and (3) temporal trends over 1951-2021. The 72-year time series of various climate and event-type indices draws a comprehensive picture of the Arctic bioclimate variability. We hope that the ARCLIM dataset opens new research opportunities aiming to better understand the impacts of climate change in Arctic terrestrial ecosystems.
Flood Impact to Urban Transport Networks Considering the Flooding Propagation
Authors: Liu Yimeng , Yang Saini , Dawson Richard , Ford Alistair , Tang Jiting
Published: February 2023

The urban transport network is threatened by urbanisation and climate change-enhanced urban flood, leading to substantial impacts on economic activities, social well-being and the environment. By taking the flood propagation process into consideration, we developed a flood-impact-assessment method to comprehensively assessed the economic impacts of traffic disruption in terms of time delay, fuel consumption and pollutant emission. The flood is simulated with CADDIES-2D flood model and the traffic flow is simulated with a microscopic model (SUMO). We applied this method to Beijing and quantified the economic damage of various flood scenarios. Comparing the baseline traffic scenario with those of three flooded scenarios yields the impacts of floods on traffic. The study revealed three key findings: (a) a rain occurring at 7 a.m. induces four times more cost than the baseline scenario, while rain of the same intensity and duration occurring at 8 a.m. or 9 a.m. lead to a traffic cost increase for 37.33% and 13.21% respectively. (b) The central and southern parts of Beijing suffer more from flooding and should be given priority for adaptation planning. (c) There is no significant spatial correlation between flood depth and traffic cost increase on a census block level. The proposed framework has the potential to assist decision-makers in prioritizing flood mitigation investments and therefore increase the resilience of transport networks to flooding impacts.  
The discovery of a Palaeozoic décollement in SW Afghanistan: orogenic events along the Tethyan edge of Gondwana-Land
Authors: Lom Nalan , Şengör A.M. Celal
Published: February 2023

The stratigraphy of the southern half of Afghanistan has been studied and the timing of first order events have been established in some detail. By contrast, the structural evolution has not been treated with the same discernment. We here report the existence of a marginal fold and thrust belt within the Logar Syncline (western Afghanistan) that was detached along a décollement surface at the base of the Cambrian, mainly between Zargaran dolomites and polymictic conglomerates filling the underlying depressions. The basement consists of Pan-African magmatic and metamorphic rocks including volcanic tuffs making up the Loy Khwar Series. Some of this material has been worked into the conglomerates of the Loy Khwar. The overlying sedimentary package reaches from the Cambrian to the Permian and has been deformed into concentric folds. Nowhere do these folds expose the underlying Pan-African basement which crops out in the extreme SW, in a kind of root zone wherein the décollement separating the sedimentary package from the basement seems to root. Having a décollement within dolomites seems unexpected due to their presumed strength but a similar case has been reported from the Keystone Thrust of the Sevier Belt in Nevada. This phenomenon seems to be more widespread than previously thought.
Airborne observations over the North Atlantic Ocean reveal the first gas-phase measurements of urea in the atmosphere
Authors: Matthews Emily , Bannan Thomas , Khan M. Anwar , Shallcross Dudley , Stark Harald , Browne Eleanor , Archibald Alexander , Bauguitte Stéphane , Reed Chris , Thamban Navaneeth , Wu Huihui , Lee James , Carpenter Lucy , Yang Ming-xi , Bell Thomas , Allen Grant , Percival Carl , McFiggans Gordon , Gallagher Martin , Coe Hugh
Published: February 2023

Despite the reduced nitrogen (N) cycle being central to global biogeochemistry, there are large uncertainties surrounding its sources and rate of cycling. Here, we present the first observations of gas-phase urea (CO(NH₂)₂) in the atmosphere from airborne high-resolution mass spectrometer measurements over the North Atlantic Ocean. We show that urea is ubiquitous in the marine lower troposphere during the Summer, Autumn and Winter flights but was found to be below the limit of detection during the Spring flights. The observations suggest the ocean is the primary emission source but further studies are required to understand the processes responsible for the air-sea exchange of urea. Urea is also frequently observed aloft due to long-range transport of biomass-burning plumes. These observations alongside global model simulations point to urea being an important, and as yet unaccounted for, component of reduced-N to the remote marine environment.  Since we show it readily partitions between gas and particle phases, airborne transfer of urea between nutrient rich and poor parts of the ocean can occur readily and could impact ecosystems and oceanic uptake of CO2, with potentially important atmospheric implications.  
Impact of individual meteors on the midlatitude ionosphere during the Leonids and Geminids meteor showers, 2019
Authors: Barta Veronika , Szárnya Csilla , Kouba Daniel , Koucka Knizova Petra , Podolska Katerina , Igaz Antal , Mosna Zbysek
Published: February 2023

The impact of individual meteors on the lower ionosphere (90-150 km height) has been investigated during wintertime meteor showers using measurements of two DPS-4D Digisondes installed at Sopron (47.63°, 16.72°) and at Pruhonice (50°, 14.5°). The optical measurements of meteors have been performed by a zenith camera installed next to the digisonde at Sopron. It provided the opportunity to compare high cadence ionograms measured during meteor showers parallel with the optical data to determine the plasma trails of individual meteors. Campaign measurements with two ionograms/minute have been performed at Sopron station during the Leonid (16-18 November) and Geminid (10-15 December) meteor showers in 2019. Furthermore, skymaps (1/min) detected by the Digisonde at Sopron during the campaign were also investigated.In the 20-25% of the observed meteors faint, short-lived (20-120 sec) Es layers were detected on the ionograms during and after (< 2 min) the optical record, which are typical signal of individual meteor trails on the ionogram based on previous studies. There was no observed Es activity at the same height on the ionograms detected before and after these events. Furthermore, the direction of the echo can be also defined on the ionograms of the DPS-4D Digisonde thanks to the multi-beam observation technique. The direction of the detected Es layers agreed well with the optical observations in most of the cases. The maximum frequency of the observed faint layers (foEs) varied between 1,6 and 4,5 MHz, while their height was between 85 and 136 km. Points on the skymaps were also detected at the time of the faint Es layers in 40 % of the cases. The height and direction of the observed points agreed with these parameters of the plasma traces on the ionograms.Comparing the ionograms with the closest ionosonde observation at Pruhonice station at the same time, we could conclude that the detected faint Es layers were local plasma irregularities, no Es activity at the same height was observed there. This strengthens the hypothesis that the observed trails on the ionograms represents the echo of the optically recorded meteors. 
Comparative study of the surface energy and mass balance of Kersten Glacier on Mt. Kilimanjaro: COSIPY versus previous modeling
Authors: Schramm Marlene , Mölg Thomas
Published: February 2023

Kersten Glacier, a slope glacier on the southern flank of Kilimanjaro, has been observed to shrink for many decades. Quantitatively, the glacier’s mass balance has been studied by Mölg et al. (2009) with a distributed physically based mass balance model. In this study, the research question is revisited using the open-source COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY; Sauter et al., 2020). A spatially distributed simulation of the surface energy and mass balance of Kersten Glacier is performed for February 2005 to January 2008. The model is driven by hourly observations from an automated weather station in the top region of the glacier at 5873 m MSL. In this contribution, we present findings such as the different components of the mass and energy balance, their temporal variation and elevational characteristics, and compare them to the results obtained from the 2009 analysis. This should allow a first assessment of COSIPY’s skill as a future tool for simulating snow and ice variability in equatorial latitudes.
Siliciclastic sediment volumes of the South-Pyrenean pro-foreland basin: Eocene exhumation and Source to Sink approach.
Authors: Juvany Philémon , Garcés Miguel , Robin Cécile , López-Blanco Miguel , Pellen Romain , Fillon Charlotte , Muñoz De La Fuente Josep Anton
Published: February 2023

The Pyrenean system has been largely studied in its globality from the tectono-sedimentary evolution of the retro and pro-foreland basins (sinks) to the exhumation history of the Axial Zone (sources) constrained by thermochronological studies.  The present estimation of the siliciclastic sediment volumes from the entire South Pyrenean pro-foreland basin completes the recent measurements made from the Aquitanian retro-foreland basin by using the same methodology. A re-evaluated complete budget of the deposited material in the southern foreland basins (South Pyrenean zone, Ebro basin and Valencia gulf) derived exclusively from the Pyrenean domain is proposed for the Early Eocene-Holocene period (56-0 Ma). Measurement of the compacted siliciclastic sediment volume is based on isopach maps (thickness maps) from Lanaja., 1987 for the Ebro and South Pyrenean zone, while volumes of the Valencia gulf were calculated from R. Pellen 2016.The volumes from the Eocene period (56-33.9Ma) will allow comparison of deposited siliciclastic sediments in both northern and southern sinks and the eroded volumes at the scale of the entire orogen (obtained from the interpolation of compiled thermochronological data) in the light of a source to sink approach.References:Lanaja, J. M. (1987). Contribución de la exploración petrolífera al conocimiento de la geología de España. IGME.Pellen Romain (2016). Géodynamique et impact de la crise d'érosion et de salinité Messinienne sur les transferts sédimentaires (bassins de Valence et Adriatique). PhD Thesis, Université Bretagne Loire. https://archimer.ifremer.fr/doc/00406/51714/
Global coronal structure and possible new insights in the upcoming perihelia of Parker Solar Probe
Authors: Badman Samuel , Rivera Yeimy , Bale Stuart , Stevens Michael
Published: February 2023

 The global structure of the Sun’s extended corona is governed by the physical processes which represent some of the biggest outstanding questions in heliophysics. These include the nature of coronal heating and solar wind acceleration. NASA’s Parker Solar Probe (PSP) offers unique new opportunities to probe this structure directly through its unprecedented orbit which takes it closer to the Sun than any prior spacecraft. As of Spring 2023, PSP has achieved perihelia of 13.3 Rs, but will continue to dive deeper to an eventual closest approach of 9.8Rs at the end of 2024. Already PSP is starting to offer tantalizing glimpses into the sub-alfvenic corona. The most recent orbits exhibit hints of an imminent global plasma regime change on multiple fronts: As well as unambiguous crossings of the Alfven critical surface, PSP sees significant solar wind deceleration, possible global magnetic field reorganization, and proton core temperatures hot enough to be comparable to isothermal solar wind models. In this talk, we will discuss how these exciting initial measurements may become decisive constraints in the latter orbits of the PSP mission. We trace the implications of making such direct measurements of the corona-solar wind transition to the science questions of coronal heating and solar wind acceleration.
Investigating A Potential Pathway for Gulf Stream Influence on the Extratropical Transition of North Atlantic Tropical Cyclones
Authors: Jones Evan , Wing Allison , Parfitt Rhys
Published: February 2023

As tropical cyclones (TCs) undergo extratropical transition (ET), they develop distinct frontal boundaries across the resulting extratropical cyclone. In the North Atlantic Ocean (NATL), this can often happen near the Gulf Stream (GS). Previous work has demonstrated that the GS can influence the development of fronts in midlatitude winter cyclones. The mechanisms of air-sea interactions associated with WBCs occur at multiple spatiotemporal scales, with the extent and exact nature of those interactions debated within the literature. Could the influence of the GS on frontal development in midlatitude winter storms also apply to storms undergoing ET? Here, we present both an observational-based statistical analysis, as well as results from case-study simulations, of a possible pathway for the GS to influence TCs undergoing ET via local small-scale SST gradient changes.Composites of NATL TCs indicate that the magnitude of the GS sea surface temperature (SST) gradient in the time prior to the TC passing is significantly weaker for TCs that begin the ET process but ultimately do not complete it, compared with TCs that do complete ET. Using a simple index of the GS SST gradient strength, both the sensible heat flux gradient and, to a lesser degree, lower-tropospheric diabatic frontogenesis are shown to scale with the local SST gradient used in this index. Our results suggest that there is some support for a mechanism in which the GS SST gradient influences the sensible heat flux gradient and subsequent surface diabatic frontogenesis in the region, impacting the favorability of the environment for a passing TC to complete ET.To investigate this possible mechanism more closely and establish causality, we use the Weather Research and Forecasting (WRF) model to test case study simulations of Hurricane Teddy as it undergoes ET near the GS. We analyze this by modifying the magnitude and strength of the local grid point-scale SST gradient strength associated with the GS in the North Atlantic in the days prior to Teddy passing over the GS. These different simulations are then compared to determine impacts in terms of the track, intensity, frontal development, strength of both the adiabatic and diabatic frontogenesis, during Teddy’s ET. These results provide insight into the dynamical mechanisms by which surface forcing could exert an influence on ET.
Effects of climate variability and change on cyclones in the Mediterranean
Authors: Doensen Onno , Messmer Martina , Kim Woon Mi , Raible Christoph
Published: February 2023

The Mediterranean is characterized by a high extratropical cyclone activity. These cyclones are an important source for water availability in the region, but at the same time they have the potential to cause extreme weather in the form of precipitation and wind extremes. The Mediterranean is heavily affected by the ongoing anthropogenic climate change, which is expected to have a profound effect on cyclones in this area. In this study, we investigate the effects of internal climate variability and anthropogenic climate change on the characteristics of Mediterranean cyclones. The analysis is based on two simulations from the Community Earth System Model 1.2 (CESM): a seamless simulation spanning 3500 years from 1500 BCE to 2012 CE and a simulation of future RCP8.5 scenario from 2013 to 2300 CE. The simulations have a 1.9°x2.5° horizontal resolution, and cyclones are identified using an established detection and tracking algorithm. Comparison with the ERA5 reanalysis for the period 1981–2010 shows that CESM is able to realistically represent cyclone frequency on a global scale, though it slightly underestimates cyclone activity in the Mediterranean. Our results indicate that cyclone activity in the Mediterranean varies on interdecadal to centennial time scales before 1850 CE. These variations are linked to positive and negative climate anomalies and fluctuations in strength of several modes of circulation, such as the North Atlantic Oscillation. The variations caused by internal variability are, however, of smaller magnitude than the effects of future climate change on the Mediterranean cyclones. In the RCP8.5 scenario, Mediterranean cyclones will become less frequent based on our simulation, and cyclone related precipitation will decrease in addition to that, which is contrary to what is being observed in other important storm track regions, such as the North Atlantic. We hypothesize that the changes in cyclone characteristics are more pronounced in the Western Mediterranean than in the Eastern Mediterranean. Overall, the study suggests that cyclone activity in the Mediterranean is projected to leave the bandwidth of variability of the last 3500 years near the end of the century.
Projected changes and uncertainty in cold surges over northern China using the CMIP6 weighted multi-model ensemble
Authors: Song Shuaifeng , Yan Xiaodong
Published: February 2023

Cold surge (CS) events are the most serious extreme cold events in winter in China, causing large economic losses and casualties. The occurrence of CS events has slightly increased since the 1990s. However, the possible future changes in these events remain unclear, and quantifying robust projected changes in CS events is important for developing adaptation and policy planning. Here, we project the occurrence of CS events and strong CS (SCS) events using the weighted multi-model ensemble (MME) of the Coupled Model Intercomparison Project 6 (CMIP6) through the application of the rank-based weighting (RBW) approach under three shared socioeconomic pathway (SSP126, SSP245, and SSP585) scenarios. The corresponding weights of each model were obtained depending on the comprehensive historical performance from three aspects: climatology, spatial variation, and interannual variability. The results show that the RBW approach can reduce the relative bias by approximately 50% compared to the unweighted MME. The occurrence of CS and SCS events shows a decreasing trend during 2015–2099 over northern China under the three SSP scenarios. There are also robust change projections during the long-term (2080–2099) and 2015–2099 periods under SSP245 and SSP585, especially in the NEC region, which exhibits a signal-to-noise ratio (SNR) that is >1. However, the occurrence of SCS events shows slight increases of 1.18% and 3.55% over northern China (notably western and eastern Northwest China) during the near-term (2020–2039) under SSP126 and SSP245, respectively. Obvious reductions in projected uncertainty are widespread throughout northern China after applying the RBW approach compared to the unweighted MME, which mainly depends on the scenario, region, and term variation. Then, a robust decreased frequency may contribute to projected changes in large-scale atmospheric circulation (a more positive AO and weaker SH and EAT) under SSP585. Our results emphasize that the weighted MME can be taken into account when projecting future extreme climate change in some areas to enhance reliability.
A marine record of Patagonian ice sheet changes over the past 140 ka
Authors: Hagemann Julia Rieke , Lamy Frank , Arz Helge W. , Lembke-Jene Lester , Martínez-Garcia Alfredo , Auderset Alexandra , Harada Naomi , Ho Ling , Iwasaki Shinya , Kaiser Jérôme , Lange Carina B. , Masafumi Murayama , Nagashima Kana , Nowaczyk Norbert , Tiedemann Ralf
Published: February 2023

Terrestrial glacial records from the Patagonian Andes and New Zealand Alps document quasi-synchronous southern hemisphere-wide glacier advances during the late Quaternary. Although detailed, these records are inherently incomplete. Here, we provide a continuous marine record of Patagonian Ice Sheet (PIS) extent over a complete glacial/interglacial cycle back to the previous glacial (~140 ka). Sediment core MR16-09 PC03, located at 46° S and ~150 km offshore Chile, received high terrestrial sediment input when the PIS advanced westward. We use biomarkers, foraminiferal oxygen isotopes, and major element data for reconstructing terrestrial sediment and freshwater input related to PIS variations. Our sediment record documents four major intervals of general PIS advance, during Marine Isotope Stage (MIS) 6 (135 – 140 ka), late MIS 5 (~85 – 95 ka), MIS 4 (~60 – 70 ka) and late MIS 3 to MIS 2 (~18 – 40 ka). These higher terrigenous input intervals occur during sea-level low stands when the western PIS covered most of the Chilean fjords which today retain glaciofluvial sediments. Superimposed, high amplitude phases of enhanced sediment supply reoccur at millennial time scales and reflect marine-based phases of the PIS with direct sediment discharge to the continental slope. We assign the late MIS 3 to MIS 2 phases and, by inference, also older advances to Antarctic stadials, consistent with the terrestrial record. Concomitantly, we observe enhanced meltwater release and conclude that the temperature-controlled PIS advances during southern hemisphere cold phases were likely reinforced by higher precipitation through enhanced westerly winds at the northwestern margin of the PIS.
On the opportunities of co-location in space for envisaged space-tie satellite missions
Authors: Glaser Susanne , Schreiner Patrick , Mammadaliyev Nijat , König Rolf , Schuh Harald
Published: February 2023

Co-location in space is an alternative combination strategy of the four main space geodetic techniques. All four of them, namely DORIS, GNSS, SLR, and VLBI, currently contributing to the determination of the terrestrial reference frame (TRF) can be combined using a so-called space-tie satellite, ideally equipped with receivers and/or transmitters for all of the techniques. The early GRASP and E-GRASP satellite mission proposals to NASA and ESA had not been recommended for the next phase, but recently, the GENESIS mission got green light from ESA which opens a unique opportunity for geodesy. We perform simulations and subsequent precise orbit determination (POD) of all four space geodetic techniques and solving also for the TRF, and combine them at one satellite using the space tie. Real data analysis including POD to prominent satellite missions like LAGEOS, TOPEX, and Sentinel-6A MF was done for most realistic simulations. In particular, the impact of biased space ties is investigated in terms of 14-parameter Helmert transformations compared to a perfect modeling solution. We will also present first simulation results of the GENESIS mission.
Divergent Response of Ocean Regions to Temporarily Overshooting Paris Agreement Warming Levels
Authors: Lacroix Fabrice , Burger Friedrich , Silvy Yona , Froelicher Thomas
Published: February 2023

Under current mitigation implementations, it is of increasing likelihood that global warming will exceed the target set by the Paris Agreement (PA) of “well below 2°C”. Correcting for this overshoot through intense carbon dioxide removal could reverse global warming back to safe levels, but the biophysical impacts associated with pathways exposing the planet to dangerous warming levels is essentially unknown. This is particularly the case for the ocean ecosystem, where peak warming could lead to ecosystem threshold exceedance and non-reversible changes. Here, we investigate spatial asymmetries in the response of surface ocean ecosystem stressors to temporarily overshooting the PA target using a novel model framework.To advance the knowledge on temporary overshoots, we utilized the Adaptive Emission Reduction Approach to design first-order emission pathways to reach given stabilization and overshoot peak temperature targets. With the help of this framework, we performed simulations with the Earth System Model GFDL-ESM2M that overshoot by 0.5°C and 1.5°C, and thereafter returns to the quasi-stabilized warming level of a simulation that respects the PA target.  Our preliminary analysis shows important differences in regional ocean characteristics between simulations that overshoot the PA target and a simulation that stabilizes at the PA target, despite ultimately reaching the same global surface temperature. For instance, regional sea surface temperatures can differ by over 0.5°C in the extreme overshoot of 1.5°C in comparison to the PA stabilization simulation, even following the overshoot. This spatial heterogeneity is illustrated through the divergent oceanic response of the polar oceans; In northern latitudes, cooler temperatures are simulated through the expansion of the North Atlantic cold spot during the overshoot, which arises through decrease of heat transport of the Gulf Stream owing to the weakening of the Atlantic Meridional Overturning Circulation (AMOC) of around 6 Sv or 30 %. In turn, the Southern Ocean is substantially warmed regionally in the overshoot simulations versus the stabilization, likely originating from increasing cross-ocean transport of heat during the overshoots, an implication that is ongoing even after the temporary overshoots return to the PA warming level. Similar spatial heterogeneities are also found for other ecosystem stressors such as O2 and pH, hinting at potential disruption of regional ecosystems. Our analysis indicates that increased assessment of regional ocean responses to temporary warming exceedance levels and their impacts for regional ecosystems are urgently needed in the scope of fully evaluating trade-offs associated with delaying climate action and overshooting the PA.      
Transmission of foreshock waves through Earth's bow shock
Authors: Turc Lucile , Roberts Owen W. , Verscharen Daniel , Dimmock Andrew P. , Kajdic Primoz , Palmroth Minna , Pfau-Kempf Yann , Johlander Andreas , Dubart Maxime , Kilpua Emilia K.J. , Takahashi Kazue , Takahashi Naoko , Battarbee Markus , Ganse Urs
Published: February 2023

The foreshock, extending upstream of the quasi-parallel shock and populated with shock-reflected particles, is home to intense wave activity in the ultra-low frequency range. The most commonly observed of these waves are the '30-second' waves, fast magnetosonic waves propagating sunward in the plasma rest frame, but carried earthward by the faster solar wind flow. These waves are thought to be the main source of Pc3 magnetic pulsations (10-45 s periods) in the dayside magnetosphere, but how the waves can transmit through the bow shock and across the magnetosheath had remained unclear. Global hybrid-Vlasov simulations performed with the Vlasiator model provide us with the global view of foreshock wave transmission across near-Earth space. We find that the foreshock waves modulate the plasma parameters just upstream of the bow shock, which in turn periodically changes the shock compression ratio and the downstream pressure. This launches fast-mode waves propagating through the magnetosheath all the way to the magnetopause, where they can further transmit into the dayside magnetosphere. We compare our numerical results with MMS observations near the subsolar point, where we identify earthward-propagating fast-mode waves at the same period as the foreshock waves, consistent with our simulation results. Our findings show that the wave propagation across the bow shock is much more complex than the simple direct transmission of the foreshock waves which was inferred in early studies.
A petrophysical model for the spectral induced polarization of clays
Authors: Leroy Philippe , Maineult Alexis , Mendieta Aida , Jougnot Damien
Published: February 2023

Clays are sedimentary minerals that are ubiquitous in the Earth’s continental crust. They have remarkable adsorption, catalytic and containment properties due to their high surface charge and very large specific surface area. However, their microstructural and electrochemical properties are not completely understood. In this study, we have developed a new petrophysical model to interpret laboratory spectral induced polarization measurements on kaolinite, illite and montmorillonite muds when salinity increases (from around 0.01 mol L-1 to 1 mol L-1 NaCl initially). Our model considers electrical conduction in the bulk and diffuse layer waters as well as polarization of the Stern layers of illite aggregates and Stern layers and interlayer spaces of Na-montmorillonite aggregates with different shapes and sizes. Maxwell-Wagner polarization was considered as well. By fitting predicted to measured SIP spectra, we found that the basal surface of clays controls Stern layer polarization and that the interlayer space of Na-montmorillonite may polarize in the mHz to kHz frequency range. Our study is a step forward to better understand the high surface conductivity response of clays inferred from resistivity and induced polarization measurements.
The temperature sensitivity of mono- and sesquiterpene emissions from terrestrial vegetation: Insights from a meta-analysis
Authors: Bourtsoukidis Efstratios , Pozzer Andrea , Williams Jonathan , Makowski David , Peñuelas Josep , Matthaios Vasileios , Economou Theo , Lazoglou Georgia , Yañez-Serrano Ana Maria , Nölscher Anke , Lelieveld Jos , Ciais Philippe , Vrekoussis Mihalis , Daskalakis Nikos , Sciare Jean
Published: February 2023

The emission of mono- and sesquiterpenes from terrestrial vegetation plays a significant role in ecological interactions and atmospheric chemistry. Previous research has suggested that global emissions of these hydrocarbons are largely driven by responses to abiotic stress and can be simulated using a fixed exponential relationship (β coefficient) between different forest ecosystems and environmental conditions. However, our meta-analysis of published emission data (89 studies/835 β coefficients) reveals that the relationship between mono- and sesquiterpene emissions and temperature is more complex than previously thought. We have found that co-occurring environmental stresses can amplify the temperature sensitivity of monoterpene emissions, which is primarily related to the specific plant functional type (PFT). In contrast, the temperature sensitivity of sesquiterpene emissions decreases over the years. On average, warmer ecosystems appear more sensitive, indicating that plants adjust their emission rates in response to thermal stress. When a PFT-dependent β coefficient for monoterpenes was implemented in a biogenic emission model and coupled with a chemistry-climate model, it was found that atmospheric processes are highly sensitive to this coefficient and subject to amplified variations under rising temperatures.
Polar climate variability during the Holocene as archived in ice core water isotopes
Authors: Hirsch Nora , Hörhold Maria , Laepple Thomas
Published: February 2023

Understanding natural climate variability, its fluctuations throughout the Holocene, and its dependency on the mean climate state can provide valuable insights into driving mechanisms and potentially allow for a better prediction of a plausible range of future climates. However, polar climate variability and its changes remain uncertain due to a lack of thorough analysis across the Holocene. Ice core water isotope records are a temperature proxy which covers both high resolutions as well as long timescales and thus enable us to resolve variability changes across a large range of frequencies. By consolidating a multitude of such records from Greenland and Antarctica and using our knowledge how the ice-core signal is recorded, we distinguish signal from noise in the spectral domain. Based on this, we examine spatial and temporal changes of the polar climate signal variability, its relationships to earth system processes and its representation in climate models.
The seasonal cycles of land biosphere N2O fluxes and atmospheric N2O
Authors: Sun Qing , Lienert Sebastian , Joos Fortunat
Published: February 2023

Nitrous oxide (N2O) is a greenhouse gas and ozone-depleting agent that is predominately emitted from the land biosphere, linking to the yet only poorly understood carbon-nitrogen cycle. The seasonal cycle of the tropospheric N2O mixing ratio (aN2O), measured at globally distributed air sampling sites, offers an observational model constraint. Recent studies attribute the aN2O seasonality to exchange with N2O-depleted stratospheric air. Yet, how land biosphere N2O fluxes contribute to the seasonal amplitude, phasing, and amplitude growth of aN2O has not been well understood at global scales.Here we apply surface-atmosphere fluxes from global simulations of the Nitrogen/N2O Model Inter-comparison Project (NMIP) and the Bern3D ocean model to atmospheric transport matrices to simulate aN2O at air sampling sites. Land N2O fluxes from eight NMIP models show broad agreement on seasonal phasing. In contrast, seasonal amplitudes of regionally averaged fluxes differ severalfold across models. For example, seasonal amplitudes range from 2.2 to 5.4 TgN yr­-1 (median: 3.7) for 20oN-40oN and from 1.1 to 4.5 TgN yr­-1 (2.3) for 40oN-60oN during 2001 to 2020. The amplitudes for these two regions increased on average by 155% and 84%, respectively, over the industrial period. The increase predominantly results from anthropogenic activities, e.g, fertilizer application. The seasonal amplitude of regional ocean-atmosphere fluxes (0.2 to 1.1 TgN yr-1) and their changes are comparably small.The NMIP land fluxes result in seasonal amplitudes of aN2O on average ranging from 0.27 to 0.84 ppb (observed: 0.23 to 0.91 ppb) at six selected stations (Alert and Barrow, Ascension Island, Ragged Point, and Samoa, and Cape Grim). The model spread in aN2O amplitude is up to 0.55 ppb and, thus, large in comparison with observations. The contributions from Bern3D ocean fluxes to aN2O seasonality at the six stations (0.13 to 0.26 ppb) are generally smaller than from land. Substantial data-model mismatches in aN2O seasonal amplitudes and phasing are likely due to neglecting stratospheric fluxes in our models.Our results demonstrate significant contributions of land biosphere N2O emissions to aN2O seasonality. Model uncertainties in land biosphere fluxes translate into large uncertainties in aN2O seasonality, calling for land biosphere model improvements. In situ aN2O observations, in combination with atmospheric transport and chemistry models, potentially provide a novel top-down constraint for global land biosphere models towards improved projections of C-N coupling, the land carbon sink, and atmospheric CO2 and N2O.
Deriving hydro-meteorological thresholds for landslide early warning using multi-layer soil moisture information
Authors: Palazzolo Nunziarita , Peres David Johnny , Creaco Enrico , Cancelliere Antonino
Published: February 2023

A key component for Landslide early warning systems (LEWS) is constituted by thresholds that provide the conditions under which landslide events can be potentially triggered. Traditionally, thresholds based on rainfall characteristics have been proposed, but recently, the hydro-meteorological approach, combining rainfall with soil moisture or catchment storage information, is increasingly gaining attention. Usually, the hydro-meteorological thresholds proposed in the literature rely on soil moisture information relating to a single layer (i.e., depth or depth range). Nevertheless, multi-layered soil moisture information can be readily provided by in-situ observations, reanalysis projects, or hydrological models. Approaches based on this multi-layered information are lacking, probably because simpler thresholds, e.g., two-dimensional, are preferred and better understood by decision makers. This study, thus, proposes a methodology, based on principal component analysis (PCA), to derive two-dimensional hydro-meteorological thresholds that use multi-layer soil moisture information. Furthermore, a piece-wise linear equation is also suggested as threshold’s shape, which can be more flexible than the traditional power-law or bi-linear thresholds. Overall, results for Sicily Island (Italy), obtained using reanalysis soil moisture data at four different depths, corroborate the advantages of the hydro-meteorological approach with respect to the traditional rainfall thresholds. Specifically, a True Skill Statistic Index (TSS) equal to 0.5 is obtained for the traditional precipitation intensity-duration threshold, while a significantly higher one is obtained for the proposed hydro-meteorological thresholds using multi-layer information condensed in one variable by PCA (TSS = 0.71). Furthermore, comparing single- vs. multi-layer threshold performances provides insights on whether shallow or deep soil depth hydrological processes are more or less influent on landslide triggering. In this regard, for the analyzed study area, the multi-layer approach provides performances in terms of TSS are similar to those obtained with single-layer soil moisture at the upper depths, 0-7 cm and 7-28 cm, pointing out that landslide occurrences in Sicily are mostly driven by surface soil moisture.  
The production of N2O from sheep urine patches is influenced by soil properties.
Authors: Hunt Danielle , Cardenas Laura , Jones Davey , Chadwick David
Published: February 2023

The urine patch from livestock creates an active hotspot of soil nitrogen (N) cycling due to the intrinsically high N and carbon (C) loading rates. These N hotspots frequently result in N losses to the atmosphere or leaching from soil. N losses vary due to climate conditions, soil conditions, and management practices. However, we do not fully understand how these factors influence N cycling and nitrous oxide (N2O) emissions from urine patches. Intensive lowland grazing systems on mineral soils have been relatively well studied in this context, however, other grazing systems such as extensive upland systems on organic soils have been much less studied.To investigate the effect of soil type on N cycling and N2O emissions in the urine patch, soil was collected from pastures in an altitudinal gradient, from an improved lowland mineral soil with coastal influence to unimproved organic soil under acid grassland.  Depending on the position along the gradient, the soils change in properties such as pH, bulk density, organic matter content, cation exchange capacity and nutrient availability. Soil was collected for a laboratory incubation study from four sites including two lowland sites (Cambisol and Cambisol with coastal influence) and two upland sites (Podzol and Histosol). Soils were sieved and divided into four replicates of each treatment. Sheep urine from Welsh Mountain ewes was applied at an equivalent loading rate of 150 kg N ha-1 to half of the soil and the remaining half received the equivalent volume of water as a control. All the treatments were held at 70% water-filled pore space to optimise both moisture conditions for nitrification and denitrification to occur. Over 100 days, greenhouse gas emissions were monitored along with soil pore water nitrate and ammonium concentrations.Soil type had an overall significant effect on N2O emissions with the highest cumulative emissions during this period being from the Podzol and the lowest cumulative emissions being from the Histosol. The two lowland sites showed no significant differences. There was a delay in nitrification in the Podzol, with the majority of the N2O being emitted a month after urine application. The Histosol showed no evidence of nitrification as there was no build-up of nitrate concentrations over the experiment. This was probably due to differences in soil pH in the soils. There were no differences in carbon dioxide or methane emissions from the four soils, but there was a spike in methane flux on the Podzol which corresponded with increases in N2O fluxes from this soil type.This experiment has shown that certain upland soils have the potential to produce N2O emissions and cycle N under optimal conditions, although this is at a much slower rate than the lowland sites. Results from this incubation study helps improve our understanding of how soil properties in organic soils affect N cycling and contribute to knowledge gaps on the sustainability of upland grazing systems.
Sub-seasonal Variations and Predictions of Precipitation over the Asian Monsoon Area with BCC_DERF2.0 in Spring-Summer Transition Season
Authors: Li Qingquan , Wang Juanhuai , Yang Song
Published: February 2023

The sub-seasonal characteristics and prediction of rainfall over the Asian Monsoon Area during spring-summer transitional season (April-May-June) are investigated using a full set of hindcasts generated by the Dynamic Extended Range Forecast operational system version 2.0 (DERF2.0) of Beijing Climate Center, China Meteorological Administration. The onset and development of Asian summer monsoon and the seasonal migration of rain belt  over East Asia can be well depicted by the model hindcasts at various leads. However, there exist considerable differences between model results and observations, and model biases depend not only on lead time, but also on the stage of monsoon evolution. In general, forecast skill drops with  increasing lead time, but rises again after lead time becomes longer than 30 days, possibly associated with the effect of slowly-varying forcing or  atmospheric variability. An abrupt turning point of bias development appears around mid-May, when bias growths of wind and precipitation exhibit significant changes over the northwestern Pacific and South Asia, especially over the Bay of Bengal and the South China Sea. This abrupt bias change is  reasonably captured by the first two modes of multivariate empirical orthogonal function analysis, which reveals several important features associated  with the bias change. This analysis may provide useful information for further improving model performance in sub-seasonal rainfall prediction.
The carbon dioxide removal gap: current removals and country proposals versus future requirements for limiting warming to 2°C or lower
Authors: Lamb William F. , Gasser Thomas , Grassi Giacomo , Minx Jan , Gidden Matthew , Powis Carter , Geden Oliver , Nemet Gregory , Pratama Yoga , Riahi Keywan , Smith Stephen , Steinhauser Jan
Published: February 2023

Steep emissions reductions are needed in the coming decades to limit warming to 2°C or lower, followed by multiple gigatons of annual carbon dioxide removal (CDR) in the second half of the 21st century. In this presentation we make a first assessment of the “CDR gap” and ask whether countries are preparing for the CDR scale-up challenge. We find that most countries pledge only a small expansion of CDR by 2030 in their nationally determined contributions (NDCs), while only a subset have proposed CDR in their long-term mitigation strategies. There is a significant gap between these proposed CDR levels and levels in scenarios that limit warming to 2°C or lower. While some scenarios have low CDR requirements, these require even steeper emissions reductions that we are not on track to achieve. Most countries prioritize conventional CDR on land (i.e. the management of forest sinks) which has low permanence and may raise land use conflicts. Conventional CDR on land will be extremely difficult just to maintain, let alone expand to meet net zero emissions targets. By contrast, countries focus far less in their NDCs and long-term strategies on novel CDR methods such as bioenergy with carbon capture and storage, direct air capture, or blue carbon. For these technologies to make a meaningful contribution to long-term climate mitigation, urgent support is required in the formative phases of their development. Above all, rapid emissions reductions are needed to reduce our dependence on CDR and prevent a widening CDR gap by 2050.