bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in ENSO characteristics in CESM1 simulations with considerably altered background climate states
Authors: Lübbecke Joke , Siuts Thea , Bayr Tobias
Published: March 2022

Changes in the tropical Pacific background state can affect interannual variability, i.e. the El Niño-Southern Oscillation (ENSO) by altering feedbacks that control ENSO’s characteristics. Here, the sensitivity of ENSO to the background climate is investigated utilizing two Community Earth System Model version 1 (CESM1) simulations in which the solar constant is altered by ±25 W/m2. The resulting stable warm and cold climate mean state simulations differ in terms of ENSO characteristics such as amplitude, frequency, asymmetry and seasonality. Under warm mean state conditions, ENSO reveals a larger amplitude and occurs at higher frequencies than in the cold mean state and control run. The warm run also features an increased asymmetry and a stronger seasonal phase-locking. We relate these changes to the differences in the mean state and the amplifying and damping feedbacks. In the warm run, a shallower mean thermocline results in a stronger subsurface-surface coupling while the cold run reveals reduced ENSO variability due to a reduced Bjerknes Feedback in accordance with a deeper mean thermocline and enhanced mean surface wind stress. A strong zonal advective and Ekman feedback further contribute to the large ENSO amplitude in the warm mean state run. However, in light of the large temperature contrast between the simulations of up to 6 K in the tropical Pacific, the results also highlight the robustness of ENSO dynamics under vastly different climate mean states.
 Positive feedback loop between burrowing earthworms and soil pH reinforces litter effects on belowground functioning
Authors: Desie Ellen , Van Meerbeek Koenraad , De Wandeler Hans , Bruelheide Helge , Domish Timo , Jaroszewicz Bogdan , Joly François-Xavier , Vancampenhout Karen , Vesterdal Lars , Muys Bart
Published: March 2022

In many terrestrial ecosystems, earthworms operate at the interface between plants and soil. Their incidence and abundance depends on several soil properties, yet simultaneously they also impact soil properties themselves. The existence of a positive feedback loop in which earthworm activity maintains their own niche — by promoting turnover rate in the forest floor, thereby increasing topsoil pH and creating suitable living conditions for themselves — has been suggested before, yet lacks supporting evidence. In our European study we found that in forests where moisture is not limiting, soil acidity is an important factor determining the context of belowground interactions, and we were able to confirm the hypothesized feedback loop for forest ecosystems with soil pH ≤ 5. This indicates that the activity of burrowing earthworms is pivotal in belowground functioning, amplifying external drivers (e.g. tree species effects) on biochemical cycling and triggering potential regime shifts in the abiotic compartment. In acidified soils (e.g. pH ≤ 5), forest management is often focused on counteracting acidification and restoring the soil nutrient status. In that regard, managing soil fauna is a promising avenue to steer belowground functioning and may even be necessary upon restoration.
Operational hydraulic flood impact forecasting with RIM2D for improved disaster management 
Authors: Apel Heiko , Vorogushyn Sergiy , Merz Bruno
Published: March 2022

The disastrous flood of July 2021 in Germany has shown that forecasts of river discharge or water levels at selected gauges do not provide sufficient information for timely and location specific warning of the population and targeted disaster management actions. The gauge forecasts as well as the available flood hazard maps were insufficient to assess the flood severity in downstream areas. In order to provide more actionable flood forecasts, the hydraulic model RIM2D was developed and setup for the Ahr river. It solves the inertial formulation of the shallow water equations on a regular grid, and is highly parallelized on Graphical Processor Units (GPUs). Moreover, the modelling concept is parsimonious and allows for fast model setup. We show that hydraulic simulations driven by the available hydrological gauge forecasts would have been feasible with short simulation duration. It would be possible to provide spatially explicit forecasts of inundation depths and flow velocities with sufficient lead time. Moreover, we also show that impact forecasts indicating human instability in water and building failure hazard can be additionally provided in operational mode. We argue that using these hydraulic and impact forecasts would have had a substantial impact on the flood alertness of the population and responsible authorities, enabling a better early warning and disaster management. This could eventually save lives during future extreme flash floods.
Evidence of wave–wave coupling between frequency harmonic bands of magnetosonic waves
Authors: Zou Zhengyang , Gao Zhonglei , Zuo Pingbing , Ni Binbin
Published: March 2022

Previous studies demonstrated that frequency harmonic structures of fast magnetosonic (MS) waves are usually excited by the hot proton instability. Here, we present an unusual event of MS waves with more than six harmonics wavebands (n = 1–6) in which their high harmonic bands are highly phase-coupled with their fundamental waveband. While calculations of the wave growth rates indicate that the local instability of the hot protons can excite the fundamental waveband (n = 1) as well as only a part of wave branches in the second and third wavebands (n = 2, 3), the bicoherence index adopted to analyze the phase coupling between different wavebands provides evidence that the wave–wave coupling between the low-frequency parts of MS waves can contribute to the generation of their higher harmonics (n > 1). Such wave–wave coupling processes have the potential to additionally redistribute the energy of MS waves and then broaden the frequency range of wave–particle interactions, which has important implications for a better understanding of the generation, distribution, and consequence of space plasma waves.
Present-day and future global economic losses associated with physical climate risks to ports
Authors: Verschuur Jasper , Koks Elco , Hall Jim
Published: March 2022

Reliable port infrastructure is essential to facilitate maritime trade across global supply-chains. Physical climate risks can disrupt port operations, which, apart from infrastructure damages (i.e. direct impacts), can have domestic and cross-border economic losses through transport dependencies on ports (i.e. systemic impacts). For instance, Hurricane Katrina (2005) disrupted operations in multiple ports in New Orleans, resulting in more than USD800 million export losses and price spikes of food products, affecting supply-chains globally (Trepte and Rice, 2014). Both climate change and changes in global trade flows (in absolute terms and trade patterns) can increase systemic risks to ports and economies in the future. In order to improve the resilience of the transport and supply-chain networks, present-day and future climate-induced systemic risks to ports need to be quantified on a global scale.

Here we present a global analysis of present-day and future systemic risk to ports due to physical climate impacts (cyclones, fluvial flooding, coastal flooding, pluvial flooding). To do this, we combine multi-hazard risk estimates of global port infrastructure (Verschuur et al. 2021, under review), covering ~1400 ports, with the output of a newly developed global maritime freight model that quantifies the dependencies of sectors and nations on ports. We show how climate-induced port disruptions can initiate economic ripple effects across geographies, although the vulnerability to these impacts differ across countries and sectors. Moreover, we project how systemic risk would increase by 2050 under various climate and trade scenarios, supporting the business case for adaptation.  

These results can help inform resilience strategies at the port-level (e.g. port elevation) , as well as the supply-chain level (e.g. diversification of transport and import). Moreover, it can support national port infrastructure planning to reduce the systemic risk.  
Non-local eddy-mean kinetic energy transfers in submesoscale-permitting ensemble simulations
Authors: Jamet Quentin , Leroux Stephanie , Dewar William K. , Penduff Thierry , Le Sommer Julien , Molines Jean-Marc , Gula Jonathan
Published: March 2022

Understanding processes associated with eddy-mean flow interactions helps our interpretation of the ocean energetic balance, and guides the development of parameterizations. Here, we focus on the non-local nature of Kinetic Energy (KE) transfers between mean (MKE) and turbulent (EKE) reservoirs. Following previous studies, we interpret these transfers as non-local when the energy extraction from the mean flow does not locally sustain energy production of the turbulent flow, or vice versa. The novelty of our approach is to use ensemble statistics, rather than time averaging or coarse-graining methods, to define the mean and the turbulent flow. Based on KE budget considerations, we first rationalize the eddy-mean separation in the ensemble framework, and discuss the interpretation of a mean flow (<u>) driven by the prescribed (surface and boundary) forcing and a turbulent flow (u') driven by non-linear dynamics sensitive to initial conditions. Our results, based on the analysis of 120-day long, 20-member ensemble simulations of the Western Mediterranean basin run at 1/60o, suggest that eddy-mean kinetic energy exchanges are largely non-local at small scales. Our main contribution is to recognize the prominent contribution of the cross energy term (<u>.u') to explain this non-locality, providing a strong constraint on the horizontal organization of eddy-mean flow KE exchanges since this term vanishes identically for perturbations (u') orthogonal to the mean flow ( Our results also highlight the prominent contribution of vertical turbulent fluxes for energy exchanges within the surface mixed layer. Analyzing the scale dependence of these non-local energy exchanges supports the local approximation usually made in the development of meso-scale, energy-aware parameterizations for non-eddying models, but points out to the necessity of accounting for these non-local effects in the meso-to-submeso scale range.
Towards an astrochronological tuned age model for the upper Pliocene–lower Pleistocene Western Foreland Basin of Taiwan
Authors: Vaucher Romain , Zeeden Christian , Hsieh Amy , Kaboth-Bahr Stefanie , Lin Andrew T. , Horng Chorng-Shern , Dashtgard Shahin E.
Published: March 2022

The stratigraphic records of shallow-marine environments are not commonly regarded as excellent climate archives because of their presumed temporal incompleteness. However, a recent study of lower Pleistocene strata in the Western Foreland Basin, Taiwan, reveals high-resolution records of past climate oscillations preserved within shallow-marine strata. Deriving such narratives is made possible because of the high accommodation and sedimentation rates in the basin, which enhanced the completeness of the stratigraphic record.

Here, we astrochronologically tune the Chinshui Shale and the lower part of the Cholan Formation of the Western Foreland Basin from approximately 3.5 to 2 Ma. These strata are calibrated to global deep-sea stable oxygen isotope (δ18O) records with established time scales detailing global climate change during the studied time period. The Chinshui Shale is mudstone-dominated and was deposited mostly in offshore settings, while the Cholan Formation comprises mainly heterolithic strata deposited in shallower settings (i.e., offshore transition, nearshore) of the paleo-Taiwan Strait. The data used herein are two borehole gamma-ray profiles through the Chinshui Shale and the Cholan Formation that have a proximal-distal relation to Taiwan. High gamma-ray values reflect clay-rich intervals and correlate to lower values of δ18O in the global reference records. Low gamma-ray values point to sand-rich packages and correlate with higher values of δ18O.

Preliminary results show that the alternating clay-rich to sand-rich deposits during the late Pliocene to early Pleistocene are orbitally paced. The results allow us to i) tune the upper Pliocene–lower Pleistocene Chinshui Shale and lower part of the Cholan Formation, ii) refine the magneto-biostratigraphic framework established for this time interval in the Western Foreland Basin of Taiwan, and iii) lay the groundwork for connecting climatic changes in Taiwan during this time period to the wider frame of global climate change. 
The Sacred Waterscape of Ancient Egyptian Temples - The Example of the Temple of Bastet at Bubastis, Nile Delta (Egypt)
Authors: Meister Julia , Garbe Philipp , Trappe Julian , Ullmann Tobias , Es-Senussi Ashraf , Baumhauer Roland , Lange-Athinodorou Eva , Abd El-Raouf Amr
Published: March 2022

The temple areas in ancient Egypt were most sacred and characterized by a multitude of elements that emphasized their importance and enabled daily cultic activities. Very specific and important features of such temples were sacred water canals or lakes, the so-called Isheru, which provided water for all kinds of purification rites and activities. In addition to textual records, preliminary sedimentological analyses of core drillings and geophysical surveys provided geoarchaeological evidence of a sacred water body at the Temple of Bastet in the ancient city of Bubastis. To further explore the location, shape, or course of the already detected canal and to find evidence on the existence of a second waterway described by Herodotus in the 5th century BCE, 34 drillings and five 2D geoelectrical measurements were carried. Drilling and sediment analyses revealed loamy to clayey deposits with a thickness of up to five meters near the northern and southern enclosures of the Temple of Bastet. 2D electrical surveying conﬁrmed the drilling results, indicating trench-formed layers of low resistivity values. The recovered deposits were interpreted as fluvial sediments, most likely deposited in a very low energy system, e.g. a canal or lake. Evidence of these fluvial sediments in numerous boreholes allows the reconstruction of two separate sacred canals both north and south of the Temple of Bastet. In addition to the course, the width of the canals of about 30 m can also be confirmed according to Herodotus' writings. The presence of numerous artefacts in the fluvial deposits, such as ceramic and limestone fragments, proves the anthropogenic use of the ancient canals. Presumably, these waterways were connected to the Nile via a tributary or canal located west or northwest of Bubastis.
Does Plant Growth accelerate Rock Weathering?
Authors: von Blanckenburg Friedhelm
Published: March 2022

A common paradigm holds that, to satisfy mineral nutrient demand, plants and associated soil microbiota accelerate rock weathering which in turn aids to regulate the silicate weathering – CO2 cycle. However, from investigating the dependence of ecosystem nutrition on 1) erosion rate; 2) biomass growth a more complex picture emerges. To derive this picture, novel metrics for budgeting element fluxes were employed in a global gradient of field sites (refs 1,2,3) that differ in erosion rate and precipitation (and thus plant growth). The metrics are based on weathering zone geochemical composition, soil production rates from cosmogenic nuclides, biomass growth, and plant stochiometry.

1) Dependence on erosion rate: From sites that differ in erosion rate it is found that in slowly eroding mountain landscapes mineral grains that contain nutrients in the regolith are depleted. As a consequence, plants are nourished by recycling, and losses are replaced by atmospheric inputs. In fast-eroding regimes, permanent natural erosion rejuvenates the weathering zone. Erosion exerts the principle control over weathering.

2) Dependence on biomass growth: Because these sites also differ in climate and biomass growth neither the degree of weathering nor the weathering rates increase systematically with precipitation or biomass growth along the gradient. A nutrient recycling factor can be quantified that increases inversely with erosion rate and shows that the increase in nutrient demand with increasing biomass growth is accommodated by faster nutrient recycling between plants and soil.

If weathering does not impact biomass growth and biomass growth does not impact weathering, what then is the influence of biota on element Critical Zone budgets? I hypothesize that plant growth might in fact dampen weathering rates. Deepening the rooting depth, modifying subsurface water flux, or reduction of porosity by precipitation of secondary minerals after enhanced mineral dissolution may induce such a negative feedback.

1. von Blanckenburg, F., Schuessler, J.A., Bouchez, J., Frings, P.J., Uhlig, D., Oelze, M., Frick, D.A., Hewawasam, T., Dixon, J., Norton, K., 2021. Rock weathering and nutrient cycling along an erodosequence. American Journal of Science 321, 1111-1163.

2. Oeser, R.A., von Blanckenburg, F., 2020. Do degree and rate of silicate weathering depend on plant productivity? Biogeosciences 17, 4883-4917.

3. Uhlig, D., von Blanckenburg, F., 2019. How Slow Rock Weathering Balances Nutrient Loss During Fast Forest Floor Turnover in Montane, Temperate Forest Ecosystems. Frontiers in Earth Science 7.
Characterization of transport from the Asian summer monsoon anticyclone into the UTLS via shedding of low-potential vorticity cutoffs
Authors: Clemens Jan , Ploeger Felix , Konopka Paul , Portmann Raphael , Sprenger Michael , Wernli Heini
Published: March 2022

Air mass transport within the summertime Asian monsoon circulation provides a major source of anthropogenic pollution for the upper troposphere and lower stratosphere (UTLS). In our study, we investigate the quasi-horizontal transport of airmasses from the Asian summer monsoon anticyclone (ASMA) into the extratropical lower stratosphere and their chemical evolution. For that reason, we developed a method to identify and track the air masses exported from the monsoon. This method is based on the anomalously low potential vorticity (PV) of these air masses (tropospheric low–PV cutoffs) compared to the lower-stratosphere, and uses trajectory calculations and chemical fields from the Chemical Lagrangian Model of the Stratosphere (CLaMS). The results show evidence for frequent summertime transport from the monsoon anticyclone to mid-latitudes over the North Pacific, even reaching high latitude regions of Siberia and Alaska. Particularly, the most promising region and time for measurements of transported anticyclonic air masses that cross the tropopause, is the North Pacific from July to August. Most of the low–PV cutoffs related to air masses exported from the ASMA have lifetimes shorter than one week (about 90%) and sizes smaller than 1 percent of the northern hemisphere (NH) area. The chemical composition of these air masses is characterised by carbon monoxide, ozone and water vapour mixing ratios at an intermediate range between values typical for the monsoon anticyclone and the lower-stratosphere. The chemical evolution during transport within these low–PV cutoffs shows a gradual change from characteristics of the monsoon anticyclone to characteristics of the lower stratospheric background during about one week, indicating continuous mixing with the background atmosphere.
Soil water retention curves determined in the laboratory and in the field
Authors: Pečan Urša , Pintar Marina , Kastelec Damijana
Published: March 2022

Soil water retention curves (SWRCs) provide information on the energy status of soil water and its availability to plants and are therefore important for irrigation management. SWRCs have traditionally been determined in the laboratory. With the development of new equipment that allows continuous measurement of soil water content and matric potential, it is possible to generate SWRCs in the field. The objective of our study was to determine SWRCs from continuous measurements in the field using dielectric methods and to see how SWRCs change over time. We compared them to SWRCs determined in the laboratory on undisturbed soil samples using the evaporation method (HYPROP®, METERgroup, Munich, Germany). Both the SWRCs determined in the field and in the laboratory were based on drying data only. Our results show significant differences between the SWRCs determined in the laboratory and in the field. For a given value of the matric potential, SWRCs in the laboratory often reach higher water contents, which can be attributed to the difference in soil wetting in the laboratory and in the field. The SWRCs constructed in the field also exhibit temporal variations. Therefore, we can conclude that the use of a single laboratory-constructed SWRC is not sufficient to describe the relationship between soil water content and matric potential.
Multiproxy paleoceanography from Broken Ridge pinpoints the onset of Tasman Leakage at 6.6 Ma
Authors: Lyu Jing , Christensen Beth , Auer Gerald , De Vleeschouwer David
Published: March 2022

Inter-basinal heat and water exchange play a prominent role in driving global climate change on astronomical timescales, as part of the global thermohaline circulation. Tasman Leakage connects the Pacific and Indian Oceans at an intermediate water depth, south of Australia. Therewith, Tasman Leakage advects heat toward the Indian Ocean, and ultimately toward the Agulhas system. Hence, Tasman Leakage constitutes a non-negligible part of the present-day thermohaline circulation. The onset of Tasman Leakage likely occurred sometime in the Late Miocene (Christensen et al., 2021), but precise geochronology for the establishment of this inter-basinal connection is still lacking. Moreover, Tasman Leakage sensitivity to astronomical forcing remains to be constrained in detail. To understand Tasman Leakage on astronomical timescales, we present a new Miocene-to-recent multi-proxy dataset from Ocean Drilling Program (ODP) Sites 752 and 754, cored on Broken Ridge (30°53.475’S), southeastern Indian Ocean.

The dataset consists of new X-ray Fluorescence (XRF) core scans that provide element contents for 18 different elements, along with benthic carbon and oxygen stable isotopic records at 4 cm resolution. The XRF-derived Ca/Fe record is paced by 405-kyr eccentricity between 22 Ma and 13 Ma (early-middle Miocene), but then becomes more sensitive to obliquity and precession forcing. The new high-resolution benthic δ13C record confirms the onset of Tasman Leakage in the Late Miocene, more specifically at 6.6 Ma. This is when the Broken Ridge benthic δ13C signature no longer reflects an Antarctic Intermediate Water signal. The benthic δ18O record shows a strong ~110-kyr eccentricity imprint, indicating that Tasman Leakage might be most sensitive to this astronomical parameter. We conclude that the Neogene nannofossil oozes, preserved on Broken Ridge, constitute an excellent paleoceanographic archive that allows us to fingerprint Tasman Leakage sensitivity to astronomical forcing.
Potential REE resources in shallow marine sedimentary phosphorite
Authors: Wang Jingya , Zhang Xiaoyu
Published: March 2022

Shallow marine sedimentary phosphorite has become a potential rare earth element (REE) resource because of its high REE content and existence worldwide. However, recent investigations have revealed that only a small percentage of shallow marine sedimentary phosphorites are enriched in REE, and it has been noted that the metallogenic mechanism, the material sources of the REE, and the sedimentary environment conducive to the accumulation of REE remain unclear at present, which limits the detailed exploration and resource evaluation of phosphorite-type REE deposits and the development of economically efficient extraction methods. Based on the collation of the temporal and spatial distributions of REE-rich phosphorite deposits worldwide, their REE fractionation patterns, their main host minerals, and the occurrence forms of the REE, the material sources of the REE and the deposition environment conducive to the accumulation of REE were investigated in this study. The results of this research show that the REE-rich phosphorites, which are mainly distributed along coastlines worldwide, are greatly affected by geological movements throughout their geological history. For example, the shallow marine sedimentary phosphorite in northwestern Xinjiang and southwestern Guizhou in China were both formed during the Early Cambrian, and they were greatly affected by the uplift of the Himalayas and the corresponding regression. Moreover, the REE contents of this phosphorite decrease from northwest to southeast. Furthermore, the hydrodynamic environment, especially upwelling, related to the REE supply and the deposition environment, as well as terrestrial input, may be the main factors inducing the formation of REE-rich phosphorites. Under intensive upwelling, the REE-rich phosphorite is repeatedly sorted, which increases the enrichment of the REE-rich phosphorite. The frequent volcanic activity in the post glacial period may also have provided the preliminary material sources of the REE during the formation of the phosphorite.

Keywords: Rare earth elements; Shallow marine sedimentary phosphorite; Geochemical characteristics; Accumulation mechanism; Material sources
Constraining zooplankton exposure to microplastic at the global scale: results from a new coupled physical-biogeochemical model (NEMO/PISCES-PLASTIC)
Authors: Richon Camille , Gorgues Thomas , Paul-Pont Ika , Maes Christophe
Published: March 2022

Zooplankton are among the most abundant animals in the ocean and are keystone species linking primary producers to higher trophic levels. Microplastics (MP) are becoming ubiquitous contaminants in the ocean that may spread through water layers from surface to bottom in all oceanic regions and be ingested by zooplankton. MP ingestion by zooplankton may lead to deleterious effects that may spread up the food-web to ultimately impact entire ecosystems. However, in situ quantification of MP contamination in the water and the biota is complex. As a result, global impacts of MP on zooplankton remain largely unknown. In this study, we use a global coupled physical-biogeochemical model providing realistic nutrient and plankton cycling, augmented with a 3D module for the representation of MP, in order to calculate the first global estimates of zooplankton exposure to MP. Results indicate that water contamination by MP is highest in the surface of subtropical gyres and coastal areas close to major MP sources, while sinking MP accumulates at the bottom of coastal zones close to their sources. We estimate zooplankton exposure to MP based on water concentrations of MP, particles and plankton and on zooplankton grazing rate. We found 2 main drivers favouring high zooplankton exposure to MP: 1) high water MP contamination, which increases zooplankton ingestion risk, even at low grazing rates and 2) intense grazing activity in productive regions increasing MP exposure even in moderately contaminated waters. Finally, despite low seasonal variability in [MP], buoyant MP may be seasonally transported to the mesopelagic waters (between 100and 1000m) by convective currents. Consequently, re-stratification of surface waters may lead to highest MP concentration in surface coinciding with planktonic blooms, thus periodically increasing contamination risk.
Calibration framework for derived flood frequency analysis driving a rainfall-runoff model with stochastically generated rainfall data 
Authors: Thiele Luisa-Bianca , Pidoto Ross , Haberlandt Uwe
Published: March 2022

For derived flood frequency analyses, stochastic rainfall models can be linked with rainfall-runoff models to improve the accuracy of design flood estimations when the length of observed rainfall and runoff data is not sufficient. Previous studies have shown here that for an optimal calibration of rainfall-runoff models, flood statistics should be considered and the same input data should be used for the calibration as for the application of the model. In general, however, the observed runoff data as annual maximum values are too short to follow the classical split-sampling approach and divide the sample into a calibration and validation period. To ensure an independent validation of the calibrated rainfall-runoff models with an increased sample size to enable split-sampling, this work will investigate a calibration framework using monthly maximum values of the observed runoff. The objective function takes into account flood statistics of monthly maximum flows, e.g. l-moments of the independent peaks and the ratios between peak and volume. The conceptual rainfall-runoff model HBV-IWW is driven by stochastically generated rainfall data on an hourly time step for 140 meso- and macroscale (30km² - 1500km²) catchments in Germany. The results of this calibration framework could be used as benchmarks for future studies.
Evolvement of irrigation-induced impacts on near-surface climate under future scenarios
Authors: Yao Yi , Thiery Wim
Published: March 2022

Recent observation-based and modelling studies have highlighted the impacts of irrigation on near-surface climate, and it has been stressed that irrigation can alleviate hot extremes, change precipitation patterns and increase air moisture. However, most of the previous studies only focused on historical periods, while potential climate change, land cover conversions and irrigation method advances may alter both the magnitudes and patterns of irrigation-induced effects, thus the influence of irrigation in the future remains uncertain. To address this question, we will employ version 2 of the Community Earth System Model (CESM2) with an updated irrigation scheme considering different irrigation techniques, to detect the impacts of irrigation on near-surface climate under different future scenarios. To include the influence of climate, land cover and irrigation method, several Representative Concentration Pathways (RCP) and Shared Socio-economic Pathways (SSP) scenarios will be selected, and different scenarios of Irrigation Method Distribution (IMD) evolvement will be designed in line with SSP scenarios for this study. Different combinations of RCP, SSP and IMD scenarios will be used to force the model, and the outputs of these experiments will be analysed and compared. We anticipate that our results will reveal how irrigation-induced impacts on near-surface climate will evolve under different scenarios.
Assessing the potential of the downscaled far-red solar-induced chlorophyll fluorescence from canopy to leaf level for drought monitoring in winter wheat
Authors: Lin Jingyu , Shen Qiu , Wu Jianjun , Liu Leizhen , Zhao Wenhui
Published: March 2022

Solar-induced chlorophyll fluorescence (SIF) from the ground, airborne to satellite-based observations has been increasingly used in drought monitoring recently, due to its close relationship with photosynthesis. SIF emissions do respond rapidly to drought, relative to the wide used vegetation indices (VIs, e.g., Normalized Difference Vegetation Index (NDVI)), thus indicating its potential for early drought monitoring. The response of SIF to drought can be attributed to the confounding effects of both physiology and canopy structure. In order to reduce the re-absorption and scattering effects, total emitted SIF (SIFtot) was proposed and served as a better tool to estimate GPP compared with top-of-canopy SIF (SIFtoc) in some studies. However, the response time and response magnitude of SIFtot to drought and its relationships with environmental parameters and soil moisture, that is, the knowledge of drought monitoring using SIFtot remains unclear. Here the continuous ground data of F760toc (SIFtoc at 760 nm) in nadir view that was downscaled to F760tot (SIFtot at 760 nm), surface soil moisture at 20cm soil layer (SM), meteorological and crop growth parameters, were measured from four winter wheat plots with different intensities of drought (well-watered treatment, moderate drought, severe drought and extreme drought) over two months. By analyzing these data, we found that F760tot was indeed more closely related to physiological and was less subjected to canopy structure than that of F760toc, but this relationship was reversed under extreme drought. It was more closely correlated with SM than VIs at short time lags, but weaker at longer time lags. The daily mean values of F760tot were able to distinguish the differences in drought gradients and respond quickly to the onset of drought, especially for the moderate drought, which appears to have the most decrease. These results demonstrate that F760tot has potential for early drought monitoring.
Peripheral and near field relative sea-level predictions using GIA models with 3D and regionally adapted 1D viscosity structures
Authors: Bagge Meike , Klemann Volker , Steinberger Bernhard , Latinovic Milena , Thomas Maik
Published: March 2022

Glacial isostatic adjustment (GIA) describes the viscoelastic response of the solid Earth to ice-sheet and ocean loading. GIA models determine the relative sea-level based on the viscoelastic deformations of the Earth interior including self-gravitation due to the loading of the water redistribution between ocean and ice and rotational effects. Choosing an Earth structure that adequately reflects the viscoelastic behavior of a region remains a challenge. For a specific region, the viscosity stratification can be inferred from present-day geodetic measurements like sea-level, gravity change and surface displacements or from paleo observations of former sea level. Here, we use a suite of geodynamically constrained 3D Earth structures that are derived from seismic tomography models and create regionally adapted 1D Earth structures to investigate to what extent regional, radially symmetric structures are able to reproduce the solid Earth response of a laterally varying structure. We discuss sea-level variations during the deglaciation in the near field (beneath the former ice sheet) and peripheral regions (surrounding the ice sheet) with focus on North America and Antarctica as well as Oregon and Patagonia. The suite of 3D Earth structures vary in transfer functions from seismic velocity to viscosity, i.e., in Arrhenius law and viscosity contrast between upper mantle and transition zone. We investigate how the relative sea-level predictions of the model suite members are affected due to the simplification of the Earth structure from 3D to 1D.

In general, our results support previous studies showing that 1D models in peripheral regions are not able to reproduce the 3D models’ predictions, because the response depends on the deformational behavior beneath the adjacent ice sheet and the local structure (superposition). Furthermore, the analysis of the model suite members shows different response behaviors for the 1D and 3D cases, e.g., suite members with weaker dependence of viscosity on seismic velocity can predict lowest RSL for the 3D case, but largest RSL for the 1D case. This indicates the relevance of the 3D structure in peripheral regions. 1D models in the near field are more capable to reproduce 3D model response behavior. But also here, deviations indicate that the lateral variations in the Earth structure beneath the ice sheet influence local relative sea-level predictions. 
Momentum- & heat- flux parameterization over the Greenland Ice Sheet
Authors: van Tiggelen Maurice , Smeets Paul C. J. P. , Reijmer Carleen H. , van den Broeke Michiel R. , van As Dirk , Box Jason E. , Fausto Robert S.
Published: March 2022

The turbulent exchange of heat at the surface, including the sensible heat flux (SHF), is an important component of the surface energy balance (SEB) over glaciers and ice sheets. Yet, the turbulent heat fluxes are parameterized in all SEB models, which makes their contribution to the modelled ice ablation uncertain.

In this study, we present several years of continuous, daily, in situ observations of SHF (eddy-covariance) and ice ablation, taken at multiple contrasting sites across the ablation area of the Greenland ice sheet. We then compare these measurements to several SEB models with different settings for the surface roughness lengths.

We show that it is possible to accurately model the SHF and the daily ice ablation, provided that the prescribed surface roughness lengths, for both heat and momentum, are accurate. We propose a simple parameterization of these roughness lengths, based on both in-situ measurements and remotely sensed data (UAV, ICESat-2).  This updated parameterization can be implemented in SEB- and climate- models for improved simulations of ice sheet ablation and surface mass balance.
Pathways of resilience in complex systems.
Authors: Rietkerk Max
Published: March 2022

The concept of tipping points and critical transitions helps inform our understanding of the catastrophic effects that global change may have on ecosystems, Earth system components, and the whole Earth system. The search for early warning indicators is ongoing, and spatial self-organization has been interpreted as one such signal. Here, we review how spatial self-organization can aid complex systems to evade tipping points and can therefore be a signal of resilience instead. Evading tipping points through various pathways of spatial pattern formation may be relevant for many ecosystems and Earth system components that hitherto have been identified as tipping prone, including for the entire Earth system.

M. Rietkerk, R. Bastiaansen, S. Banerjee, J. van de Koppel, M. Baudena and A. Doelman. 2021. Evasion of tipping in complex systems through spatial pattern formation. Science 374 (169): abj0359.
Foehn air warming in six Alpine valleys: Lagrangian heat budget analysis and relation to airstreams
Authors: Jansing Lukas , Sprenger Michael
Published: March 2022

Foehn air parcels are typically associated with a pronounced warming within lee-side valleys. While the physical mechanism of this warming has been disputed for over a century, recent studies emphasize the key role of both adiabatic descent (isentropic drawdown), but also turbulent mixing and upstream latent heating in clouds, depending on the Foehn case and the region. This study aims to attribute the warming to adiabatic descent and key diabatic processes for six major Alpine Foehn valleys in Switzerland and Austria. To this end, a mesoscale model simulation including online trajectories is combined with a Lagrangian heat budget to investigate how relevant the different processes are for an intense and long-lasting South Foehn event in November 2016.

In agreement with earlier findings for the Alpine Foehn, adiabatic descent constitutes the most important process for the majority (57%) of air parcels arriving within the six Foehn valleys. Nonetheless, upstream latent heating in clouds is more important for a considerable number (35%) of air parcels. On the one hand, the Lagrangian analysis reveals a clear difference between western and eastern Alpine valleys, as adiabatic warming gradually becomes more important for the eastern valleys. On the other hand, a distinct temporal evolution is identified, where diabatic processes emerge as the main warming mechanism for the western valleys during the central phase of the Foehn event.

As the contribution for diabatic heating varies strongly for the different Foehn valleys, it is used to subdivide the Foehn trajectories into three different airstreams. Air parcels associated with intense diabatic heating are typically advected within a low-level easterly barrier jet in the Po Valley before traversing the Alps. Diabatically cooled air parcels, on the other hand, originate at higher levels and are quasi-horizontally advected from the south towards the Alpine crest. Hence, the varying intensity of the contributing airstreams dictates the dominating warming mechanism. The results prevent a clear separation into ‘Swiss Foehn’ and ‘Austrian Foehn’, as, in our case study, both varieties either simultaneously occur in the different valleys, or distinct time periods of the Foehn within a valley are more or less dominated by either or the other airstream.
Surface ocean biogeochemistry regulates the impact of anthropogenic aerosol Fe deposition on iron and iron isotopes in the North Pacific
Authors: König Daniela , Conway Tim , Hamilton Douglas , Tagliabue Alessandro
Published: March 2022

Long-range atmospheric transport and deposition of anthropogenically-sourced aerosol iron (Fe) affects surface ocean biogeochemistry far from the emission source. However, it is challenging to establish the integrated impact of anthropogenic aerosol Fe on surface ocean dissolved Fe (dFe) cycling, due to other Fe sources and in situ cycling processes. Previous work has used a distinctively-light Fe isotopic signature (δ56Fe) associated with anthropogenic activity to track the contribution of anthropogenic Fe at the basin scale. However, this requires not only the determination of the δ56Fe endmember of all potential Fe sources, but also the assessment of how upper ocean biogeochemical cycling modulates surface ocean dFe signatures (δ56Fediss). Here we accounted for dust, fire and anthropogenic Fe deposition fields in a global ocean biogeochemical model with an integrated δ56Fecycle to quantify the impact of anthropogenic Fe on surface ocean Fe and δ56Fe, with a focus on the North Pacific. The effect of anthropogenic Fe is spatially distinct and seasonally variable in our model, depending on the biogeochemical state of the upper ocean. In the subtropical regions where Fe is not limiting, anthropogenic Fe input leads to increased dFe levels and, at times, phytoplankton Fe uptake. δ56Fediss declines due to the very light anthropogenic δ56Fe endmember, most prominently in low dFe areas of the subtropical North Pacific gyre. In Fe-limited systems, such as the subpolar gyre, anthropogenic Fe stimulates both primary production and Fe uptake with little change to summertime dFe levels. Moreover, the decrease in δ56Fediss is amplified as extra Fe dampens the impact of the fractionation effects associated with Fe uptake and complexation, whereby the overall δ56Fediss often remains positive. Overall, it is important to account for biological parameters, such as primary productivity or Fe limitation, when assessing the oceanic impact of anthropogenic Fe.
The decreasing vulnerability of French crop production to climatic hazards
Authors: Schauberger Bernhard , Makowski David , Ben-Ari Tamara , Boé Julien , Ciais Philippe
Published: March 2022

Recent adverse weather events in Europe have questioned the stability of crop production systems. We assessed the vulnerability of eleven major crops in France between 1959 and 2018 as a function of climate, crafting a novel hazard framework that combines exposure and sensitivity to weather-related hazards. Exposure was defined as the frequency of hazardous climate conditions, while sensitivity of crops was estimated by the yield response to single and compound hazards. We used reported yields available at departement (county) level. Vulnerability was computed as the exposure-weighted average of crop sensitivities. Our results do not reveal any historical evidence for an increased vulnerability of French crop production. Rather, the sensitivity to adverse weather events, and thus the overall vulnerability, has significantly decreased for six of the eleven crops between 1959 and 2018, and shown no significant decline or remained stable for the other five. Yet compound hazards can induce yield losses of 30% or more for several crops. Moreover, as heat-related hazards are projected to become more frequent with climate change, crop vulnerability may rise again in the future. Our results may support insurance design by identifying single and compound hazards that can severely affect yields.
Fidelity of the CMCC SPS model in simulating the dominant mode of tropical variability in boreal winter
Authors: Shahi Namendra Kumar , Scoccimarro Enrico , Gualdi Silvio , Peano Daniele , Navarra Antonio
Published: March 2022

The dominant modes of variability at the sub-seasonal to seasonal (S2S) time scales in the tropical atmosphere, with particular emphasis on the Madden-Julian oscillation (MJO), is investigated using the observed NOAA outgoing longwave radiation (OLR). This study focuses on the boreal winter season (November to April) of the period 1993-2016. The multi-channel singular spectral analysis (MSSA) method is introduced and used to isolate the dominant modes associated with the tropical boreal winter daily OLR anomalies. The results show that the dominant MSSA mode consists of an intraseasonal oscillation with a period of around 35-day and two seasonally persistent modes. The 35-day oscillation is related to the intraseasonal convective activity of the tropics with little contribution to the seasonal mean value, and the phase composites and propagation characteristics of the 35-day mode are almost identical to the MJO (referred to as the MJO mode). The seasonally persistent modes are characterized by large-scale patterns that prevail over most of the tropics with the same sign anomalies throughout the boreal winter season, which represent inter-annual variations and are related to the El Niño-Southern Oscillation (ENSO) pattern. In this work, the MSSA based analysis is applied to the fully coupled (atmosphere-ocean-land-cryosphere) Euro-Mediterranean Center on Climate Change (CMCC) seasonal prediction system to evaluate the model's performance in simulating observed dominant modes of the boreal winter tropical variability.
Hysteresis and orbital pacing of the early Cenozoic Antarctic ice sheet
Authors: Van Breedam Jonas , Huybrechts Philippe , Crucifix Michel
Published: March 2022

The early Cenozoic Antarctic ice sheet has grown non-linearly to a continental-scale ice sheet close to the Eocene-Oligocene boundary when environmental conditions were favourable. These favourable conditions included the movement of the continent towards the South Pole, the thermal isolation of the Antarctic continent and declining atmospheric CO2 concentrations.  Once the threshold for ice sheet growth was reached, a series of positive feedbacks led to the formation of a continental-scale ice sheet.

The thresholds for growth and decline of a continental scale ice sheet are different. The ice sheet state is dependent on the initial conditions, an effect called hysteresis. Here we present the hysteresis behaviour of the early Cenozoic Antarctic ice sheet for different bedrock elevation reconstructions. The ice sheet-climate coupler CLISEMv1.0 is used and captures both the height-mass balance and the ice-albedo feedback accurately. Additionally, the influence of the different orbital parameters on the threshold to glaciation and deglaciation is investigated in detail. It appears that the long-term eccentricity cycle has a significant influence on the ice sheet growth and decline and is able to pace the ice sheet evolution for constant CO2 concentration close to the glaciation threshold.