The Paleocene–Eocene Thermal Maximum (PETM) is associated with climatic change and biological turnover. It shares features with the Oceanic Anoxic Events (OAEs) of the Mesozoic, such as transient global warming and biogeochemical perturbations. However, the PETM experienced a more muted expansion of marine anoxia compared to the Mesozoic OAEs (especially OAE 2), with benthic deoxygenation being geographically restricted and limited evidence for photic zone euxinia. We explore the extent and drivers of marine deoxygenation during the PETM using biomarkers for water column euxinia and anoxia and data-constrained biogeochemical climate model (cGENIE) simulations. These reveal that the water column in the North-East Peri-Tethys became anoxic during the PETM, with euxinic conditions reaching the photic zone. Our simulations show that this developed due to a global increase in the ocean nutrient inventory, similar to findings for OAE 2. The particularly strong regional response in the NE Peri-Tethys appears to arise from a combination of global forcing and regionally restricted circulation. Unlike OAE 2, anoxia and PZE do not become widespread in our PETM simulations, consistent with geochemical and biological indicators. This globally muted response could result from a reduced oceanic phosphate inventory prior to the PETM and/or a smaller increase during it relative to the mid-Cretaceous ocean. Our observations suggest that similar feedback mechanisms operated in response to disparate Cenozoic (PETM) and Mesozoic (OAEs) transient global warming events, while also highlighting that background conditions such as geography and nutrient status are crucial in modulating the sensitivity of Earth’s system to them.

We apply three different methods based on the analysis of the multi-component seismic data to detect seismovolcanic tremors and other seismovolcanic signals, to propose an approach to classify them and to locate their sources. We use continuous seismograms recorded during one year by 21 stations at the Piton de la Fournaise volcano (La Réunion, France). The first method allows to detect seismovolcanic signals based on stability in time of the inter-components cross-correlations function. Two other methods based on the simultaneous analysis of the whole network can be used to detect seismovolcanic signals and to locate their sources. In a second approach, the seismic wavefield is analyzed by calculating the width of the network covariance matrix eigenvalue distribution. The third method consists in performing the 3D back-projection of the inter-stations crosscorrelations in order to calculate the network response function. Simultaneous analysis of the parameters measured by the three different methods can be used to classify different types of seismovolcanic tremors. Our results demonstrate that all three methods efficiently detect seismovolcanic tremors accompanying the 2010 eruptions and the preceding pre-eruptive seismic swarms. Furthermore, methods 2 and 3 based on simultaneous analysis of the whole network detect a large number of volcanic earthquakes. Our location results show that each seismovolcanic tremor is located in a distinct region of the volcano, close to the eruptive site at a shallow depth and the preceding seismic crisis is located deeper at about the sea level under the summit crater.

The evolution of subduction zones influences the rise and demise of forearc and back-arc basins on the overriding plate. We conducted 2D elasto-visco-plastic numerical models of oceanic subduction and subsequent continental collision which include erosion, sedimentation, and hydration processes. The models show the evolution of wedge-top and retro-forearc basins in the continental overriding plate, separated by a forearc high. These forearc regions are affected by repeated compression and extension phases. Higher subsidence rates are recorded in the syncline structure of the retro-forearc basin when the slab dip angle is higher and the subduction interface is stronger and before the slab reaches the 660 km upper-lower mantle discontinuity. The 3-4 km negative residual topographic signal is produced by the gradually steepening slab, which drags down the overlying upper plate. Extensional back-arc basins are either formed along inherited crustal or lithospheric weak zones at large distance from the arc region or are created above the hydrated mantle wedge originating from arc rifting. Back-arc subsidence is primarily governed by crustal thinning controlled by slab roll-back. Onset of collision and continental subduction is linked to the rapid uplift of the forearc basins; however, the back-arc region records ongoing extension during the initial phase of soft collision. Finally, during subsequent hard collision both the forearc and back-arc basins are ultimately affected by compression. Our modelling results provide insights into the evolution of Mediterranean subduction zones and propose that the Western-Eastern Alboran, Paola-Tyrrhenian, Transylvanian-Pannonian Basins should be considered as genetically connected forearc –back-arc basins, respectively.

Current ozone (O3) concentration levels entail significant damages in crop yields around the world. The reaction of the emitted precursors (mostly methane and nitrogen oxides) with solar radiation contribute to O3 levels that exceed established thresholds for crop damage. This paper shows current and projected (through 2080) relative yield losses driven by O3 exposure for different crops and the associated economic damages applying crop prices that are calculated per region and period. We adjust future crop yields in the Global Change Assessment Model (GCAM) to reflect the RYLs and analyse the effects on agricultural markets. We find that the projected decreases in O3 precursor emissions in a reference scenario would reduce the agricultural damages, compared to present, for most of the regions, with a few exceptions including India, where higher future O3 concentrations have large negative impacts on crop yields. The annual economic impact of O3 driven losses from 2020-2080 are 5.0-6.0, 9.8-18.8, 6.7-10.6 and 10.4-12.5 B$(2015) for corn, soybeans, rice and wheat, respectively, with the large losses for wheat and soybeans driven by their comparatively high sensitivity to O3. When O3 effects are considered, the projected change on O3 levels and the subsequent variations of yields, would directly affect future agricultural markets. Therefore, the aggregated net present value (NPV) of the crop production would be reduced around 116 B$(2015). However, these changes are not distributed evenly across regions, and the net present market value of the crops would increase up to 270 B$(2015) or decrease up to 120 B$2015 (China)

In 27 October 2012 the ULF wave in Pc4 range being Alfv'en wave was observed with Van Allen Probe A. In the event the parallel Poynting flux of the wave was directed towards the Northern ionosphere. Assuming that this may be caused by the asymmetry of ionospheric conductivity between the Northern and Southern hemispheres, its effect on the standing structure of the Alfv'en wave was investigated in this paper. For this purpose the analytical model with straight magnetic field lines was used. As a result the method for estimation of the Northern and Southern ionospheric conductivity was developed. It allows us to reconstruct the parallel structure of Alfv'en waves under various conditions of the ionospheric conductivity. With the method developed, the ionospheric conductivity for the October 27, 2012 event was evaluated and compared with ionosphere model IRI-2016.

Rapid economic development and expansion of the human population in China have made China currently the world’s largest producer and consumer of reactive Nitrogen (Nr), leading to severe damage to human and ecosystem health. In this context, managing N is fundamental to sustainable development in China. An accurate N budget is a basis for effective N management and evidence-based decision-making to tackle both food security and environmental protection challenges. However, significant disparities exist among previous estimates of N budgets and fluxes flow. This study attempts to advance understanding of uncertainties in China’s N budget using the Coupled Human And Natural Systems (CHANS) model and Monte Carlo simulation from 1980 to 2018. Results show that the spatial and temporal variations in agricultural and industrial activities and insufficient knowledge on N cycling parameterization are the two dominant causes of uncertainties in the N budget in China. Uncertainties of N inputs generally are <10%, while they are <30% for N outputs and >30% for N accumulations. Uncertainty of nitrogen oxides emission is more sensitive to energy consumption due to the large contributions from industry and transportation, while the uncertainty of ammonia emission is predominantly affected by agricultural activity. Combining surface measurements, satellite observations, and atmospheric simulation models enables cross-check of N fluxes in multiple systems and reduce uncertainties of the N budget.

We applied a polarization analysis of InSight seismic data to estimate the temporal variation and frequency dependence of the Martian ambient noise field. Low-frequency (<1 Hz) P-waves show a diurnal variation in their dominant back-azimuths that are apparently related to wind and the direction of sunlight in a distant area. Low-frequency Rayleigh waves (0.25–1 Hz) show diurnal variations and a dominant back-azimuth related to the wind direction in a nearby area. Low-frequency signals that are derived mainly from wind may be sensitive to subsurface structure deeper than the lithological boundary derived from an autocorrelation analysis. On the other hand, dominant back-azimuths of high-frequency (>1 Hz) waves point toward the InSight lander, especially in daytime, indicating that wind-induced lander noise is dominant at high frequencies. These results point to the presence of several ambient noise sources as well as geologic structure at the landing site.

The Mw 7.2 Sarez strike-slip earthquake occurred on Dec 7, 2015 in the Pamir region at the North-West of the Tibetan Plateau. We used Sentinel-1A/B Interferometric Synthetic Aperture Radar (InSAR) data to investigate postseismic deformation due to the Mw 7.2 Sarez earthquake. We analyzed 2.5 years of post-earthquake acquisitions from the ascending track 100 and the descending track 005. Despite challenging surface conditions (that include rugged topography and snow cover), we were able to derive time series of line of sight (LOS) displacements within 150 km from the earthquake rupture. We used stacks of interferograms covering snow-free months, as well as persistent scatterers to detect possible deformation transients. Preliminary results indicate no postseismic relaxation signals above the noise level (10-20 mm/yr for average LOS velocities). We do observe coseismic deformation due to two M>6 earthquakes that occurred ~100 km to the North-East from the epicenter of the Sarez earthquake. We use constraints on the maximum amplitude of surface displacements provided by the InSAR data to provide bounds on the effective rheologic structure of the lower crust and upper mantle beneath Pamir.

The Sun’s chromosphere is a highly dynamic, partially ionized region where spicules (hot jets of plasma) form. Here we present a two-fluid MHD model to study the chromosphere, which includes ion–neutral interaction and frictional heating. Our simulation recovers a magnetic-canopy shape that forms quickly, but it is also quickly disrupted by the formation of a jet. Our simulation produces a shock self-consistently, where the jet is driven by the frictional heating, which is much greater than the ohmic heating. Thus, our simulation demonstrates that the jet could be driven purely by thermal effects due to ion–neutral collisions and not by magnetic reconnection. We plan to improve the model to include photo-chemical effects and radiation.

Aerosol can affect clouds in various ways. Beside the micro-physical impact of aerosol particles on cloud formation, the interference of aerosol with atmospheric radiation leads to changes in local heating, surface fluxes and thus meso-scale circulations all of which may also modify clouds. Rather little is known about these so-called semi-direct effects in realistic settings-a reason, why this study investigates the impact of absorbing aerosol particles on cloud and radiation fields over Germany. Using advanced high-resolution simulations with grid spacings of 312 and 625 m, numerical experiments with different aerosol optical properties are contrasted using purely-scattering aerosol as control case and realistic absorbing aerosol as perturbation. The combined effect of surface dimming and atmospheric heating induces positive temperature and negative moisture anomalies between 800 and 900 hPa impacting low-level cloud formation. Decreased relative humidity as well as increased atmospheric stability below clouds lead to a reduction of low-level cloud cover, liquid water path and precipitation. It is further found that direct and semi-direct effects of absorbing aerosol forcing have similar magnitudes and equally contribute to a reduction of net radiation at the top of the atmosphere .

The 2008 Wenchuan Mw 7.9 mainshock has caused catastrophic destruction to cities along the northwestern margin of the Sichuan Basin. The Wenchuan-Maoxian Fault (WMF) on the hinterland side, along with a conjugate buried Lixian fault (LXF) was not activated by this earthquake but is likely to experience large earthquakes in the future. We perform 3D dynamic earthquake rupture simulations on the WMF and LXF to access the possibility of the earthquake occurrence and further explore the possible size of earthquakes and the distribution of high seismic risk in the future. We firstly invert focal mechanism solutions to get a heterogeneous tectonic stress field as the initial stress of simulation. Then we develop a new method to refine fault geometry through inverting long-term slip rates. Several fault nucleation points, friction coefficients, and initial stress states are tested, and the general rupture patterns for these earthquake scenarios are evaluated and could fall into three groups. Depending on initial conditions, the dynamic rupture may start in the LXF, leading to magnitude-7.0 earthquakes, or start in the WMF, then cascades through the LXF, leading to magnitude-7.5 earthquakes, or both start and arrest in the WMF, leading to around magnitude-6.5 or 7.0 earthquakes. We find that the rupture starting on the reverse oblique-slip tends to jump to the strike-slip fault, but the reverse process is suppressed. The rupture propagating eastward causes larger coseismic displacements than the westward propagation, and relatively high peak ground velocities are distributed near the northeastern end of WMF.

Constraining the properties of continental margin where dynamic interplay between the lithosphere and convective upper mantle actively occurs can provide implications to understand the evolution and modification process of cratonic lithosphere. Cratonic lithosphere in the eastern Eurasian plate has experienced multiple episodes of tectonic events at the continental margin during the Phanerozoic, which are characterized by collision and subduction of continental and oceanic plates with extensive magmatic intrusion, extension, and rifting. To better understand the complex tectonic processes and their influences on the continental lithosphere, we imaged upper mantle structure beneath the Archean-Proterozoic basement in the Korean Peninsula (KP) by seismic tomography. Our dataset is entirely based on relative arrival time of teleseismic body wave recorded by dense seismic array across the southern KP in order to extract velocity variations from the local area and reduce the effects from deeper upper mantle structures. The images show a sharp and large lateral velocity variation within a short distance (< 200 km) in KP, which indicates highly variable lithospheric structure. An anomalously thick high-velocity structure beneath the southwestern part suggests a fragment of a long-lasting cratonic lithosphere (~150 km) at the continental margin. The absence of deep lithosphere and mostly occupied by hot, buoyant, low-velocity upper mantle beneath the Gyeonggi massif, Gyeongsang continental arc-backarc system, and eastern continental margin of KP shows highly modified regions. In addition, there are clear spatial correlations of low-velocity upper mantle with partial melting zones and the localities of Cenozoic basalts, high surface heat flux, and high topography with recent uplift along the eastern mountain ranges. A strong variation in the upper mantle velocity structure without clear distinctions in surface geology across different massifs suggests heterogeneous modification of continental lithosphere by recent and transient processes, such as the opening of the East Sea (Sea of Japan) or a subduction of Philippine Sea Plate. Dynamic interaction of the prominent lithospheric structure and convective upper mantle has controlled reactivation and destabilization at the cratonic margin of KP.

The paper investigates the applicability of machine learning (ML) to weather prediction by building a reservoir-computing-based, low-resolution, global prediction model. The model is designed to take advantage of the massively parallel architecture of a modern supercomputer. The forecast performance of the model is assessed by comparing it to that of daily climatology, persistence, and a numerical (physics-based) model of identical prognostic state variables and resolution. Hourly resolution 20-day forecasts with the model predict realistic values of the atmospheric state variables at all forecast times for the entire globe. The ML model outperforms both climatology and persistence for the first three forecast days in the midlatitudes, but not in the tropics. Compared to the numerical model, the ML model performs best for the state variables most affected by parameterized processes in the numerical model.

This research study shows the ability of cloud resolving models (CRM) to simulate Mesoscale Convective Systems (MCS) over the far Eastern Pacific region, off the coast of Colombia and Panama. The simulation period coincides with the newly developed OTREC field campaign (August-September, 2019), which provided enhanced upper-air soundings, NSF/NCAR G-V dropsonde and HIAPER Cloud Radar data to help evaluate the model and diagnose the environmental conditions favoring MCS development. We tested the model sensitivity to three different microphysics schemes: two popular bulk schemes (Thomson and Morrison) and one spectral bin (SBM) scheme. The models are diagnosed on their ability to simulate the observed large-scale and mesoscale environments associated with MCSs development, including the ChocoJet and Caribbean low-level jets, the semi-permanent Panama low, vertical shear, and mid-level diurnal gravity waves. We also examined the vertical distribution of hydrometeors concentrations and diabatic heat and cooling profiles. Results show that not only the SBM represents better the spatial and vertical distribution of precipitation, but also simulates better MCSs characteristics (intensity, duration, organization) and their predominant westward movement. We hypothesize that the success of the SBM in producing better organized and more long-lasting MCS stands in the stronger diabatic heating, related to a top-heavier mass profile that helps support upper-level convergence, and more intense low-level diabatic cooling that helps support stronger gravity currents. OTREC observations and CRM results shed light on the role of MCSs in the generation of enhanced mid-level mesoscale vorticity, which has been related to generation of easterly waves or enhancement of existing ones. Although the SBM is unpractical due to its computation cost (fast version takes about 10-12 times longer), it represents an important step forward in cloud modeling, with suggestive results indicating that SBM improves confidence of the physical basis of the elusive and challenging simulation of realistic tropical MCSs.

Due to global warming, heat stress is becoming a major challenge especially in cities where an intensification of the urban heat island effect is observed and further expected. Climate change adaptation measures are a key strategy to mitigate heat stress and health consequences. Successful adaptation should cool down both indoor and outdoor conditions. As indoor heat is mainly caused by wall heat flux, measures like green, blue or blue-green roofs or facades are a promising approach. These measures on buildings can also easily be scaled as they do not require additional space. However, cooling effects of evaporation-based measures are largely limited by water availability to enable latent heat flux and reduce wall heat flux at extreme heat events or prolonged drought periods. Rainfed water storage systems at buildings like cisterns with a PV-driven pumping mechanism not only supply water for greenings or wet roofs during hot days, but also store storm water to reduce flooding risks. This research aims to simulate heat mitigation effects of rainfed nature-based and technical solutions on buildings using the physically-based high-resolving microclimate model ENVI-met in contrasting climatic conditions. A 3D gridded 16 ha model domain of an urban high-density area in the mid-latitude city of Cologne/Germany and monsoon driven city of Pune/India was parameterised using field observations and remote sensing data. Both models are validated based on a setup quality-controlled, densely-distributed microclimate sensor network. Scenario analyses are performed to quantify cooling effects of intensive/extensive roof greenings, (non-)ground-based facade greenings, wet roofs and combinations. Specific water demands for irrigation of greenings or blue roofs from a managed local rainfed storage are determined to analyse how often and effectively the systems can be operated. Simulation results show significant potential cooling effects in both study areas which are stronger for Pune. Due to water scarcity in the Indian pre-monsoon season, actual heat mitigation potentials are significantly lower than in Cologne as measures can rarely be operated for extreme heat waves at the end of the season. To effectively improve thermal comfort in monsoon conditions, potentials of other measures will be simulated in further research.

Future socio-economic and climate changes can profoundly impact water resources, food production, bioenergy generation, and land use, leading to a broad range of societal problems. In this study, we performed future projections by using a land integrated model, MIROC-INTEG-LAND, that considers land surface physics, ecosystems, water management, crop growth, and land use, under various socio-economic scenarios (Shared Socio-economic Pathways, SSPs). Under the sustainability scenario (SSP1), demands for food and bioenergy are kept low, so that the increase in cropland areas for food and bioenergy are suppressed. On the contrary, in the middle of the road and regional rivalry scenarios (SSP2 and SSP3), cropland areas are projected to increase due to high demand for food and bioenergy. The expansion of cropland areas is projected to increase the water demand for irrigation and CO2 emissions due to land use change. MIROC-INTEG-LAND simulations indicate that the impacts of the CO2 fertilization effect and climate change on crop yields are comparable, with the latter being greater than the former under climate scenarios with high greenhouse gas concentrations. We also show that the CO2 fertilization effects and climate change play important roles in changes in food cropland area, water demand for irrigation, and CO2 emissions due to land use change. Our results underscore the importance of considering Earth-human system interactions when developing future socio-economic scenarios and studying climate change impacts.

A challenge to managing water resources is characterizing the scale-dependent heterogeneity created by the interactions among hydrological, ecological and anthropological processes. It is often difficult to collect sufficient empirical data over the range of scales required to construct mathematical models that facilitate robust bottom-up descriptions or predictions. An alternative is identifying emergent properties of complex systems, whose components self-organize into novel structures or processes via their collective interactions with each other and the environment. A new level of organization and complexity emerges that cannot be predicted from or attributed to the components alone. Emergence offers a number of perspectives from which to interpret, if not predict, the behavior of complex water resource systems. One of these is entropy, which maximizes the options for system components to alter their interactions and, thus, permits variability and adaptability. At the scale of watersheds, increased entropy is pertinent because of its relationship to information (as probability functions), which is transmitted through connected components of a watershed in a manner such that the accrued information gives rise to emergent properties. Hence, analyzing the behaviors of a system according to emergence introduces the possibility of evaluating the information content via its interconnected components. Connectivity then assumes an integral role in a hydrologic system’s response to natural or anthropogenic disturbances (e.g., climate change, land use). Replacing the details of multi-scale heterogeneity and causal mechanisms with the functions that watersheds perform allows processes such as stream flow rate/duration and flood frequency to be construed as emergent spatiotemporal patterns. A reductionist or bottom-up approach to assessing the behavior of aquatic systems shifts to a functional or top-down approach that does not depend upon an understanding of all the physical, chemical or biological mechanisms involved. This latter approach could supplement conventional water resource descriptions and predictions via more comprehensively characterizing watershed or aquatic ecosystem functions.

The ACT-America Earth Venture mission conducted five airborne campaigns across four seasons from 2016-2019, to study the transport and fluxes of Greenhouse gases across the eastern United States (US). Unprecedented spatial sampling of atmospheric tracers (CO2, CO, and COS) related to biospheric processes offers opportunities to improve our qualitative and quantitative understanding of seasonal and spatial patterns of biospheric carbon uptake. Here, we examine co-variation of boundary layer enhancements of CO2, CO, and COS across three diverse regions: the crop-dominated Midwest, evergreen-dominated South, and deciduous broadleaf-dominated Northeast. To understand the biogeochemical processes controlling these tracers, we compare the observed co-variation to simulated co-variation resulting from model- and satellite- constrained surface carbon fluxes. We found indication of a common terrestrial biogenic sink of CO2 and COS and secondary production of CO from biogenic sources in summer throughout the eastern US. Stomatal conductance likely drives fluxes through diffusion of CO2 and COS into leaves and emission of biogenic volatile organic compounds into the atmosphere. ACT-America airborne campaigns filled a critical sampling gap in the southern US, providing information about seasonal carbon uptake in southern temperate forests, and demanding a deeper investigation of underlying biological processes and climate sensitivities. Satellite- constrained carbon fluxes capture much of the observed seasonal and spatial variability, but underestimate the magnitude of net CO2 and COS depletion in the Southeast, indicating a stronger than expected net sink in late summer.