The biological pump and deep-ocean ventilation in eastern equatorial Pacific (EEP) Ocean are thought to play a crucial role in cases of global CO2 change. However, the integral role of these two processes in regulating atmospheric CO2 perturbations over major climate transitions are still unknown. Here, we present the magnetofossil record in EEP sediments from Sites 1333 and 1218 across the Eocene-Oligocene Transition (EOT) when the major ice-sheet was first established on Antarctica. We find that the EEP dust fertilization and bottom-water oxygenation were well co-archived by magnetofossil in characteristics of abundance and morphology, respectively. Our observations show a coeval decline of EEP biological productivity and deep-ocean ventilation during the Antarctic glacial expansion, and suggest that the reduced deep-ocean ventilation contributed to the global CO2 decline across the EOT, whereas the superimposed biological pump action provided a negative (stabilizing) feedback in the meantime.

The region of Japanese island arc is one of the most seismically active regions of the world due to very high plate convergence rate. On March 11, 2011., the great Mw=9.0 Tohoku earthquake occurred in the central segment of the Japanese subduction zone, the region where the previous megathrust earthquake was in 869. To identify the spatiotemporal variations of surface deformations following the 2011 earthquake we analyzed more than 7 years of continuous GNSS observations from over 1400 stations of GEONET network that covers the entire territory of Japanese islands. Coseismic displacements captured by GNSS stations allowed us to model the slip distribution in the earthquake source and to revealed significant effect of Fossa Magna Graben on the coseismic deformations pattern. The observed surface displacements before, during and after the Tohoku earthquake exhibited good agreement with the expected motions implied by the keyboard model of subduction zones [Lobkovsky and Baranov, 1984] at the appropriate stages of the seismic cycle. At the same time, analysis of the displacement rate variations estimated over 1-year intervals after the Tohoku earthquake showed an intense ongoing postseismic motion of complex mechanism. We tested a hypothesis of significant afterslip in the earthquake source using 1-month cumulative displacements for the first half of the year after the earthquake. The slip distribution in the earthquake source and afterslip process were modelled using open-source software package STATIC1D of F. Pollitz. We also used the open-source software package VISCO1D of F. Pollitz to test the influence on surface deformations of rapid viscoelastic relaxation caused by coseismic slip. Our analysis of the afteslip process showed that its maximal contribution rapidly decreases in the first six months after the earthquake from 1-3 meters to 10-20 centimeters per month and cannot predict the observed long-term displacements.

Geophysical logs collected from a deep borehole drilled to the Canadian Shield in Northeastern Alberta shed valuable lights on the state of stress in stable cratons. Observed breakout azimuths rotate between three depth intervals, from N100°E at 1650-2000 m to N173°E at 2000-2210 m, and finally to N145°E at the bottom. No obvious fractures that might disturb stresses were found; and these rotating breakouts can be interpreted either as being due to a heterogenous stress field or formation elastic and strength anisotropy. The latter interpretation is favored because the breakout azimuths are strongly controlled by rock metamorphic textures as validated by their close correlations with both dip directions of foliation planes and polarization directions from dipole sonic logs. Monte Carlo realizations further demonstrate that anisotropic metamorphic rocks subjected to a uniform horizontal stress direction could result in the observed azimuth-rotating breakouts. The stress magnitudes inferred from this analysis, which incorporates both the rock anisotropy and weak foliation failure planes, suggest a normal faulting regime and a maximum horizontal compression direction consistent with that in the overlying Western Canadian Sedimentary Basin (NE-SW) and the motion of the North American plate. The inferred stress magnitudes are low and Mohr-Coulomb analyses demonstrate that the formation is not near the critical loading for slip on weak planes. However, more detailed investigations should be conducted since Monte Carlo calculations indicate that analyses from breakout widths, particularly when a conventional Kirsch-based formula is employed, are highly nonunique, allowing for large variations in potential stress states.

A document by Georgia Sotiropoulou. Click on the document to view its contents.

In the field geophysical instruments, various seismic sensors (an accelerometer, a velocimeter) and auxiliary equipment in the form of recorders (loggers) have been designed, which provide wireless information transfer to the data collecting and processing center. On the basis of these, instrumental earthquake observation systems have been developed to ensure the integrated security of critical facilities. These systems can be transformed to control global seismic monitoring of the territories, dams, also facilities of critical importance such as nuclear power plants, bridges, tunnels and technological pipelines for chemical and oil-processing plants. The report presents the technical characteristics of the above mentioned instruments and the possibilities of their wide application in different countries. Additionally, monitoring of seismicity of Armenian regions is implemented for the earthquake research.

Percolation theory addresses the spatial and temporal scaling properties of disordered networks, both for topological and transport-related processes. The critical zone is, effectively, a random network. The ability to predict the dimensions of the critical zone as a function of time, as well as its carbon storage properties, are both critical to the understanding of its dynamics. In addition, combining the scaling relationships with the principal that represented ecosystems will tend to optimize net primary productivity, generates a basic understanding of the water cycle. When the future of hydrology is discussed, these facts should be of central importance. Furthermore, although the definition of complex systems is not necessarily generally agreed on, it is usually understood that phase transitions, such as described by percolation theory, are emergent phenomena within the range of topics encompassed. Thus, this topic is of fundamental relevance to the present conference.

The Chilean subduction zone is one of the most seismically active regions on Earth. Focal zones of earthquakes with magnitude M>8, registered in this region for the last 200 years, cover almost the entire length of the Chilean coast. In 2010 the Darwin seismic gap existing from 1835 between the focal zones of 1960 Great Chilean earthquake and the 1985 Valparaiso earthquake was interrupted by the Maule earthquake Mw = 8.8. We analyzed the data of 8 years of continuous observations at 27 sites of the Chilean GPS network in order to distinguish coseismic and postseismic deformations in the vicinity of the 2010 earthquake. The analysis of postseismic deformations is based on the ground displacement velocities estimated over 1-year intervals. We used the keyboard model of subduction zones [Lobkovsky and Baranov, 1984] combined with the model of viscoelastic relaxation in the asthenosphere and the upper mantle to explain the variety of motions observed in the region of Central Chile. We model viscoelastic relaxation caused by coseismic slip using the open-source software package VISCO1D of F. Pollitz. The coseismic displacements captured by the sites close to the epicenter of the 2010 event amounted to 1 to 3 meters, which characterizes the magnitude of the displacements of seismogenic blocks at the time of the earthquake. All the coseismic displacements are directed toward the ocean, which agrees well with the predicted movements of the blocks in the seismic stage of the seismic cycle. Data from the first two years after the 2010 event show attenuating site offsets toward the ocean over the whole Central Chile region which indicates passage of aftershock stage of the seismic cycle. Over the next 5 years the observed displacements can be explained by the process of restoring the stationary state of stress accumulation for seismogenic blocks in the frontal part of the subduction zone in combination with the continuing motion of the rear block with viscous asthenospheric flow. The duration of the viscoelastic relaxation process for the Maule earthquake is estimated to last for more than 15 years.

Gamma radiation over the Atlantic Ocean Gamma radiation over the Atlantic Ocean was measured continuously from January to May 2020 by a NaI(Tl) detector installed on board the Portuguese navy's ship NRP Sagres. Enhancements in the gamma radiation values are identified automatically by an algorithm for detection of anomalies in mean and variance as well as by visual inspection. The anomalies are typically +50% above the background level and relatively rare events (~ < 10% of the days). All the detected anomalies are associated with simultaneous precipitation events, consistent with the wet deposition of scavenged radionuclides. The enhancements are detected in the open ocean even at large distances (+ 500 km) from the nearest coastline. Back trajectories reveal that half of these events are associated with air masses experiencing continental land influences, but the other half don't display evidence of recent land contact. The enhancements in gamma radiation very far from land and with no evidence of continental fetch from back trajectories are difficult to explain as resulting only from radionuclides with a terrestrial source such as radon and its progeny. Further investigation and additional measurements are needed to improve understanding on the sources of ambient radioactivity in the open ocean and assess whether gamma radiation in the marine environment is influenced not only by radionuclides of terrestrial origin, but also cosmogenic radionuclides, like Beryllium-7, formed in the upper atmosphere but with the ability to be transported downward and serve as a tracer of the aerosols to which it attaches.

During summer, the Southern Ocean is largely unaffected by anthropogenic emissions, which makes this region an ideal place to investigate marine natural aerosol sources and processes. A better understanding of natural aerosol is key to constrain the preindustrial aerosol state and reduce the aerosol radiative forcing uncertainty in global climate models. We report the concentrations of gaseous sulfuric acid, iodic acid, and methanesulfonic acid (MSA) together with a characterization of new particle formation (NPF) events over a large stretch of the Southern Ocean. Measurements were conducted on board the Russian icebreaker Akademik Tryoshnikov from January to March 2017. Iodic acid is characterized by a particular diurnal cycle with reduced concentration around noon, suggesting a lower formation yield when solar irradiance is higher. Gaseous MSA does not have a diurnal cycle and measured concentrations in gas and condensed phase are compatible with this species being primarily produced via heterogeneous oxidation of dimethyl sulfide and subsequent partitioning into the gas phase. We also found that NPF in the boundary layer is mainly driven by sulfuric acid but it occurred very rarely over the vast geographical area probed and did not contribute to the CCN budget in a directly observable manner. Despite the near absence of NPF events in the boundary layer, Aitken mode particles were frequently measured, supporting the hypothesis of a free tropospheric source. Iodic acid and MSA were not found to participate in nucleation, however, MSA may contribute to aerosol growth via heterogeneous formation in the aqueous phase.

Hydrological studies pivot on the proper understanding of the drainage system that is under investigation. It is imperative to delineate the catchment and better visualise the area, especially in headwater catchment assessments. Advances in technology have improved how catchments are delineated and visualised. This has become integral to understanding how the river system is distributed and the basis for hydrological studies. Against this background, this research delineated the Luvuvhu Headwater Catchment (LHC) using high-resolution Digital Elevation Models (DEMs). The Shuttle Radar Topography Mission (SRTM) Global DEMs with a cell size of 30m resolution were used. Four DEMs covering the study area were mosaicked before analysis and processed to 10m x 10m resolution. The research results were compared against the conventionally used maps in similar studies. The delineated map showed a highly defined stream network that was more detailed than the previously used maps. The use of high-resolution DEMs thus produced a detailed stream distribution of the LHC. Coupling catchment delineation with ground-truthing will enhance the understanding and sustainable management of headwater catchments.

A reach-scale high resolution digital elevation model (DEM) of the Congo’s main stem bathymetry is presented. The Bathymetry DEM covers a multichannel reach of the main stem situated in the Cuvette Centrale, and is developed from a series of in-situ measurements of bathymetry, water surface elevation and discharge that were obtained during a CRuHM fieldtrip in summer 2017. The main stem’s complex network of channel threads requires a bathymetry modelling methodology that is capable of intelligently interpolating the raw bathymetry measurements. The methodology must also estimate a significant portion of the bathymetry, since it is not feasible to measure the entire extent of the massive and complex channel network that this study reach is comprised of. This methodology is also presented. Remote sensing from satellites is increasingly being used to resolve the scarcity of contemporary hydrological and hydrographic measurements in the Congo Basin. However, river channel bathymetry information cannot yet be reliably obtained from remote sensing methods. This is problematic since river channel representation has been shown to be an essential input into a hydraulic model. Analyses of satellite observations suggest that, relative to other global rivers, in-channel flows on the Congo’s main stem represent a relatively large proportion of total flows through the river-floodplain system. This implies the Congo’s in-channel bathymetry may play a relatively large role in controlling Congo main stem hydrodynamics. When used in a hydraulic model, the bathymetry DEM presented here will provide new information on Congo in-channel hydraulics and the extent to which bathymetry controls the Congo’s middle reach hydrodynamics. It will help better quantify the capacity of the Congo main stem channels through the Cuvette Centrale, and thus provide further insights into the extent to which the main stem channel floods in this region. It is also intended to be used for testing simplified methods of Congo bathymetry representation that are necessary for larger scale hydraulic models.

Large storms are considered to be influential drivers of morphologic change on open sandy coasts. Whereas storm-driven morphologic changes and the recovery processes that typically follow have been robustly documented, less well understood is the concept of storm-driven coastal behavior over seasonal to annual timescales, which integrates multiple storm response and recovery cycles. In this study, storm controls on coastal evolution are evaluated using a topographic dataset containing monthly measurements of the intertidal and subaerial beach for 5 years (2009-2014) along a 10 km reach of open sandy coast fronting NASA-Kennedy Space Center near Cape Canaveral, Florida. In addition to shoreline and volume change analyses, a novel Empirical Orthogonal Function (EOF) analysis has been applied to these data to extract dominant spatial and temporal patterns of morphologic change over the full beach surface, as opposed to being applied over individual cross-shore transects or alongshore contours as previously practiced. Results indicate that the most dominant pattern of morphologic evolution within these data describes an isolated change of state to this system initiated by the impact of Hurricane Sandy (2012). This is exhibited physically as a southward migration of a previously stable cuspate foreland beginning immediately after the storm, resulting in nearly 600 m of propagation over the following 1.5 yr observation interval. Additionally, remaining dominant patterns describe a seasonal erosion cycle linked to storm driven seasonality in nearshore water levels, and a spatially variable berm formation cycle on inter-storm timescales likely driven by storm-induced variations in sediment storage locations and associated availability to non-storm hydrodynamics. These results illustrate that coastal response to an individual storm may control the recovery processes that follow by shifting morphologic equilibria such that processes of recovery drive the beach toward a configuration unlike its pre-storm state. Because these post- event processes influence morphologic response to the next event, the results presented here highlight a largely unexplored coupling between storm response and recovery that may be considered a dominant control on interannual-scale coastal evolution in storm-prone regions.

GOSAT (Greenhouse gases Observing SATellite) observations ameliorate inversion analysis of greenhouse gas emissions. Meso-scale atmospheric transport model (AIST-MM, National Institute of Advanced Industrial Science and Technology-Mesoscale Model) and global-scale transport model (NICAM-TM, Nonhydrostatic ICosahedral Atmospheric Model-Transport Model) have been coupled for GOSAT data assimilation in order to estimate CO2 emission from mega-city Tokyo. However, forests in the north and west of Kanto region, of which Tokyo Metropolis is the center, generate significant biogenic CO2 fluxes and such atmosphere-biosphere gas exchange remains to be properly calculated during the modeling processes. In this study, we use MODIS products to simulate regional GPP (gross primary production), vegetational and soil respirations based on BEAMS (Biosphere model integrating Eco-physiological And Mechanistic approaches using Satellite data) algorithms. By integrating this atmosphere-terrestrial ecosystem carbon balance module to our regional inversion analysis, we aim at more precise estimation of CO2 emission from Tokyo. Reference https://doi.org/10.1175/1520-0450(1995)034<1439:TTILWA>2.0.CO;2 https://doi.org/10.2151/jmsj.79.11 https://doi.org/10.2151/jmsj.2011-306 https://doi.org/10.1029/2005JG000045 https://doi.org/10.1016/j.rse.2011.03.007

The importance of measurement and modelling of the coronal magnetic fields has been appreciated for a long time, and in view of the fact that magnetic fields of Coronal Mass Ejections (CMEs) play a crucial role in determining their geo-effectiveness, this also has considerable societal impact. The coronal magnetic fields are, however, very hard to measure directly. Unlike those at play in X-ray, EUV and optical regimes, radio emission mechanisms are sensitive to the local magnetic fields and hence can potentially lead to their measurements. In practise, however, this potential has been hard to realize. To the best of our knowledge, in the past eighteen years, there have been only three published instances of radio detection of CME like structures. Only for two of these instances, it was possible to estimate coronal magnetic fields by fitting the measured spectra with gyrosynchrotron models. Using data from the Murchison Widefield Array (MWA), for two CMEs we have detected radio structures resembling the CME morphology. These structures are cospatial and cotemporal with the white light coronagraph images of the CME and we can convincingly demonstrate that this is not plasma emission. The maximum heliocentric distance where we can detect such emission is 4.74 solar radii, and the flux densities we measure are among the lowest reported. We note that these detections have been enabled by the confluence of the availability of data from the modern arrays like the MWA; and an automated interferometric solar radio imaging which we have developed. The MWA provides unprecedentedly dense sampling of Fourier (uv) plane, an essential pre-requisite for high imaging fidelity; and the imaging pipeline is tuned to extract the best imaging performance from these data. We present the hypothesis that gyrosynchrotron emission from CMEs intrinsically is not rare, it only appeared so because the dynamic range and imaging fidelity of available solar radio images was typically insufficient to convincingly detect this emission. If true, this then provides an exciting opportunity for routine estimation of the CME magnetic fields at coronal heights and a host of other coronal diagnostics, uniquely associated with gyrosynchrotron emissions.

North-east region of Bangladesh is comprised of hilly transboundary rivers in the upstream and complex river network along with floodplain in the downstream. In this study, a satellite observation and numerical modeling based near real-time flash flood forecasting framework is developed for the north-east part of Bangladesh. For nowcast information, Global Precipitation Measurement Mission (GPM) developed latest near real-time IMERG precipitation product is chosen. To produce improved quality precipitation forecasts, Global Forecasting System (GFS) based precipitation predictions are corrected by applying climatology based bias adjustment technique. Flow from upstream river channels into the complex river network are calculated by using the nowcast and forecast precipitation products forced into Soil and Water Assessment Tool hydrological Model. The inflow discharges from the hydrological model then used in HecRAS hydrodynamic model to produce forecasted water height/discharge, flood depth and inundation in prominent locations in the study region. Both of the hydrological and hydrodynamic models are simulated sequentially in sub-daily scale to produce 120 hours lead time forecasts. SWAT Model was calibrated and validated in six inflow stations using rated discharge. HecRAS Model was calibrated and validated using measured water level at different locations.

Coseismic and rainfall-triggered landslides are a common hazard in many terrains, and the risk associated with them can be quantified, usually by probabilistic modelling. These events are well-documented as a special case of a cascading hazard chain, and the assessment is commonly done via spatial modelling of susceptibility (suppressing temporal dependence) or tailoring models to specific areas and events. The interaction between Earthquakes and rainfall is not usually implemented in a model, as it is considered coincidental. However, because landslides have multiple triggering factors, there is a need for a statistical model that incorporates both features, in a manner such that the separate and joint effects can be estimated. This helps with understanding the interactions between primary events in the triggering of a single secondary hazard type that is crucial for generally applicable multi-hazard methodologies. The presented work aims at the apportioning of the relative and combined effect on landslide triggering by earthquakes and rainfall using a discrete approximation to a multivariate hierarchical point process. Doing so provides a building block in a general framework with the potential to be extended to other chains of events. A case study on the Italian region of Emilia-Romagna is included, using one of the longest and most complete landslide data sets known. Multiple models for the rainfall-earthquake interaction in landslide triggering are trialed, with the best explanation being additive effects from rainfall intensity, rainfall duration and coseismic triggering.

Chapter 27 of the 4th U.S. National Climate Assessment, Volume 2, assesses climate impacts, future risks, and adaptation in Hawai‘i and the U.S.-Affiliated Pacific Islands. The author team collaboratively developed the chapter’s Key Messages and narrative. Webinars and an informal survey of stakeholders informed the selection of focal sectors. To be inclusive of the vast region and expertise, the authors convened six half-day workshops on key sectors, including remote participation from experts in the U.S. Affiliated Pacific Islands. In all, the chapter involved more than 60 technical contributors. Authors reviewed major areas of risk and new understanding since the last national assessment, including on issues such as: (1) reliable and safe water supplies, (2) marine and terrestrial ecosystem health, (3) sea level rise and coastal impacts, (4) impacts on community livelihoods and well-being, including Indigenous peoples. Under these climate-related challenges to island sustainability, diverse groups are coming together to combine forward-looking policies with adaptation strategies. An integrated theme throughout the chapter is that early intervention can lower the economic, environmental, and social and cultural costs from a changing climate.

Red mangroves, Rhizophora mangle, in coastal areas have proven to be resilient for many decades. Mangroves accumulate mud, peat and plant matter through aerial roots (Pneumatophores) consist of rigid and flexible roots oscillating in the water. The oscillation of the flexible root not only decreases erosion but also provide a source of renewable energy. These oscillations can essentially be harvested as electrical power from tidal currents of the shallow coastal water in the form of pollution free energy by converting the kinetic energy of the moving fluid into voltage. We present an elastically mounted rigid patch of circular cylinders as simplified flexible mangrove roots to understand the role of flexibility on the vortex-induced vibration phenomena for energy harvesting. We performed kinematics and PIV measurements inside a water channel for the cylinders limited to a transverse oscillation inside a water tunnel at constant velocities . We investigate the effect of Reynolds number, mass ratio, damping ratio, and natural frequency of the system on the range of the achievable voltage. Higher flexibility resulted in increasing the frequency of oscillations with a reduction in the reduced velocity. This bio-inspired design has potentials for future electricity generations, as tidal currents are more predictable than wind energy and solar power as well as environmentally friendly due to minimal alterations to ecosystems and marine life.