EG - Encyclopedia topics

Removal efficiency of carbon and nitrogen in constructed wetlands is inconsistent and does not reveal whether the removal processes are from physical attenuation or transformation to other reactive forms. Previous research did not consider "pollution swapping" driven by transformational processes. Herein the biogeochemical dynamics and fate of carbon and nitrogen and their potential impact on the environment, as well as novel ways in which these knowledge gaps may be eliminated, are explored.

The Global Carbon Budget 2017 describes data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. It is the 12th annual update and the 6th published in this journal.

African natural ecosystems and agricultural lands are a significant source of GHG. However, there are huge research gaps and understanding of Africa's contribution to global GHG emissions remains highly uncertain. The strategy for addressing this data gap involves identifying priorities for data acquisition, utilizing appropriate technologies, and establishing networks and collaboration.

An accurate assessment of the methane budget is important to understand the atmospheric methane concentrations and trends and to provide realistic pathways for climate change mitigation. The various and diffuse sources of methane as well and its oxidation by a very short lifetime radical challenge this assessment. We quantify the methane sources and sinks as well as their uncertainties based on both bottom-up and top-down approaches provided by a broad international scientific community.

Weather and climate models consist of complex software evolving in response to both scientific requirements and changing computing hardware. After years of relatively stable hardware, more diversity is arriving. It is possible that this hardware diversity and the pace of change may lead to an inability for modelling groups to manage their software development. This chasm between aspiration and reality may need to be bridged by large community efforts rather than traditional in-house efforts.

The development of coupled ocean atmosphere climate models is a complex process that inevitably includes multiple calibration steps (sometimes called tuning). Tuning uses degrees of freedom allowed by uncertainties in model approximations to modify parameters to make the simulation better align with some selected observed target(s). We describe how these tuning targets, parameters, and philosophy vary across six US modeling centers in order to increase the transparency of the practice.

We present a review of the make-up of 20 models participating in the Chemistry–Climate Model Initiative (CCMI). In comparison to earlier such activities, most of these models comprise a whole-atmosphere chemistry, and several of them include an interactive ocean module. This makes them suitable for studying the interactions of tropospheric air quality, stratospheric ozone, and climate. The paper lays the foundation for other studies using the CCMI simulations for scientific analysis.

The Paleoclimate Modelling Intercomparison Project (PMIP) takes advantage of the existence of past climate states radically different from the recent past to test climate models used for climate projections and to better understand these climates. This paper describes the PMIP contribution to CMIP6 (Coupled Model Intercomparison Project, 6th phase) and possible analyses based on PMIP results, as well as on other CMIP6 projects.

Atmospheric dynamical cores are a fundamental component of global atmospheric modeling systems and are responsible for capturing the dynamical behavior of the Earth's atmosphere. To better understand modern dynamical cores, this paper aims to provide a comprehensive review of 11 dynamical cores, drawn from modeling centers and groups that participated in the 2016 Dynamical Core Model Intercomparison Project (DCMIP) workshop and summer school.

This review article compiles the characteristics of the gas chlorine nitrate and discusses its role in atmospheric chemistry. Chlorine nitrate is a reservoir of both stratospheric chlorine and nitrogen. Formation and sink processes are discussed, as well as spectral features and spectroscopic studies. Remote sensing, fluorescence, and mass spectroscopic measurement techniques are introduced, and global distributions and the annual cycle are discussed in the context of chlorine de-/activation.

Landscape fire plume height controls fire emissions release in the atmosphere, in particular their transport that may also affect the longevity, chemical conversion, and fate of the plumes chemical constituents. Here, we review how such landscape-scale fire smoke plume injection heights are represented in large-scale atmospheric transport models aiming to represent the impacts of wildfire emissions on component of the Earth system.

Biomass burning is one of the largest sources of atmospheric pollutants worldwide. This paper presents an up-to-date compilation of emission factors for over 120 trace gas and aerosol species from the different forms of open vegetation fires and domestic biofuel use, based on an analysis of over 370 published studies. Using these emission factors and current global burning activity data, the annual emissions of important species released by the various types of biomass burning are estimated.

This is a synthesis of the atmospheric mercury (Hg) monitoring data available in recent years (2011–2015) in the Arctic and in Antarctica along with a comparison of these observations with numerical simulations using four cutting-edge global models. Based on this comparison, we discuss whether the processes that affect atmospheric Hg seasonality and interannual variability are appropriately represented in the models, and identify remaining research gaps.

Reliable quantification of air-surfaces flux of elemental mercury vapor (Hg⁰) is crucial for understanding Hg global biogeochemical cycles. In this study, we provide a comprehensive review on the state of science in the atmosphere-surface exchange of elemental Hg. We compiled an up-to-date global observational flux database and discuss the implication of flux data on global Hg budget. The knowledge gap and research needs for future measurements and modeling efforts were discussed.

For more than 20 years, scientists and engineers have tried to design simple sampling devices that can collect gaseous elemental mercury from the atmosphere without the use of a pump. A thorough review of the sampler designs that have been presented so far suggests that while some may be suitable for measuring higher air concentrations close to sources, none of them have the accuracy and precision required to record the low atmospheric mercury concentrations prevalent in background regions.

Accurately projecting future climate change requires a good methane modeling. However, how good the current models are and what are the key improvements needed remain unclear. This paper reviews the 40 published methane models to characterize the strengths and weakness of current methane models and further lay out the roadmap for future model improvements.

This study made an detailed understanding on production, consumption and fluxes of methane from different sub-ecosystems of Sundarbans mangrove forest. The mangrove environment was found to be rich in organic carbon content as well as methane concentration. A most of the produced methane transported to the atmosphere where 85 % of total supply undergoes photo-oxidation. Like sediment estuaries are also methane supersatuarated and about 70 % of methane within estuary undergoes microbial oxidation.

Silver iodide is one of the best-investigated ice nuclei. It has relevance for the atmosphere since it is used for glaciogenic cloud seeding. Nevertheless, many open questions remain. This paper gives an overview of silver iodide as an ice nucleus and tries to identify the factors that influence the ice nucleation ability of silver iodide.

Tropospheric {H₂O,δD} pairs can be observed by remote sensing techniques, but the data quality strongly depends on a comprehensive consideration of the complex nature and a careful calibration of the remote sensing data pairs. This paper reviews the quality assurance/documentation activities of the MUSICA project and demonstrates that MUSICA’s ground-based FTIR and space-based IASI {H₂O,δD} pair products are accurate and can be generated at a global scale with high resolution and for long periods.

Because a systematic difference between measurements of water vapor performed by space-borne observing instruments in the microwave spectral domain and their numerical modeling was recently highlighted, this work discusses and gives an overview of the various errors and uncertainties associated with each element in the comparison process. Indeed, the knowledge of absolute errors in any observation of the climate system is key, more specifically because we need to detect small changes.

This paper serves as an introduction to the special issue "Twenty-five years of operations of the Network for the Detection of Atmospheric Composition Change (NDACC)". It describes the origins of the network, its actual status, and some perspectives for its future evolution in the context of atmospheric sciences.

Vegetated coastal habitats (mangroves, seagrass meadows, salt marshes and macroalgal beds) are key contributors to the marine carbon budget, but remain hidden in the representation of the coastal carbon budget. While they have been acknowledged to play an important role in carbon burial, this is small compared to the export flow, which may lead to carbon sequestration beyond these habitats. The carbon fluxes supported by vegetated coastal habitats are globally relevant.

Plankton models have become an integral part in marine ecosystem and biogeochemical research. These models differ in complexity and in their number of parameters. How values are assigned to parameters is essential. An overview of major methodologies of parameter estimation is provided. Aspects of parameter identification in the literature are diverse. Individual findings could be better synthesized if notation and expertise of the different scientific communities would be reasonably merged.

Australian vegetation phenology is highly variable due to the diversity of ecosystems on the continent. We explore continental-scale variability using satellite remote sensing by broadly classifying areas as seasonal, non-seasonal, or irregularly seasonal. We also examine ecosystem-scale phenology using phenocams and show that some broadly non-seasonal ecosystems do display phenological variability. Overall, phenocams are useful for understanding ecosystem-scale Australian vegetation phenology.

This paper provides the formalism and examples of how observation operators can be used, in combination with data assimilation or retrieval techniques, to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models.

This review synthesized current knowledge of deep-sea food webs and provided a preliminary analysis of global geographic patterns in the biochemical composition of deep-water organisms. Our results revealed both latitudinal and depth wise trends in the biochemical composition of deep-sea animals. In addition, the link across latitudes between surface primary production and deep-water communities was highlighted, which has important implications in the face of global climate change.

A new method of observing ocean heat content throughout the entire ocean depth is provided. The new method is compared with simulated ocean heat content changes from climate models. The comparisons are carried out in various depth layers of the ocean waters. It is found that there is excellent agreement between the models and the observations. Furthermore, we propose that changes to ocean heat content be used as a fundamental metric to evaluate climate models.

Geomorphometry, the science of quantitative terrain characterization, has traditionally focused on the investigation of terrestrial landscapes. More recently, a suite of geomorphometric techniques have been applied to characterize the seafloor. The dynamic, four-dimensional nature of the marine environment and differences in data collection methods cause issues for geomorphometry that are specific to marine applications. This article offers the first review of marine geomorphometry to date.

TEOS-10 is the present international standard for thermodynamic properties of water, ice, seawater and humid air recommended for geosciences by leading international organisations such as UNESCO/IOC and IUGG. TEOS-10 incorporates an extended manifold of different experimental data for those substances, collected from publications over many decades, in an unprecedentedly compact, consistent, comprehensive and accurate way.

This paper provides a comprehensive review and up-to-date synthesis of the observed changes in air temperature, precipitation, seasonal snow cover, mountain glaciers, permafrost, freshwater ice cover, and river discharge over the interior of western Canada since the mid- or late 20th century. Important long-term observational networks and data sets are described, and qualitative linkages among the changing Earth system components are highlighted.

In the field of Disaster Risk Reduction (DRR), there is a proliferation of research into different ways to measure, represent, and ultimately quantify differential social vulnerability to natural hazards. This study shows how the same census data but three alternative multivariate methodologies can lead to radical differences in our assessment of the most vulnerable population groups to flood risk. A case study of the 2013 floods in the Parrett catchment, Somerset (UK), provides context.

Vertisols are cracking clayey, arable soils that often overlay groundwater reservoirs. The soil cracks enable flow that bypasses soil blocks, which results in both relatively fresh recharge of the underlying groundwater and contamination with reactive contaminants. These special phenomena, as well as unique mechanism of salinization after cultivation and relative resilience to contamination by nitrate typical to groundwater under vertisols, are reviewed in this study.

This paper compiles most of the studies (as far as the authors are aware) on the design of sensor networks for measurement of precipitation and streamflow. The literature shows that there is no overall consensus on the methods for the evaluation of sensor networks, as different design criteria often lead to different solutions. This paper proposes a methodology for the classification of methods, and a general framework for the design of sensor networks.

This study presents a systematic review of 128 papers that apply multi-criteria decision-making (MCDM) tools to flood problems, aiming to provide an overall picture of what has motivated researchers in 37 different countries over the past 2 decades. A wide range of applications were identified, highlighting the utility of MCDM as a decision support tool in all stages of the flood management process.

This research reviews flood risk within the Lagos area of Nigeria over the period 1968 to 2012. During this period, floods have caused harm to millions of people physically, emotionally, and economically. Arguably over this period the efforts of stakeholders to address the challenges appear to have been limited by, among other things, lack of reliable data, lack of awareness among the population affected, and lack of knowledge of flood risk mitigation. Recommendations are made for flood modeling.

We apply the green- and blue-water perspective to Amazonia's water resources to highlight trade-offs that may arise with future land use change. We question how future irrigation may supply additional water vapour to the atmosphere with growing agricultural production. Maintaining precipitation recycling could prevent degradation of rainfall-dependent terrestrial ecosystems and has the potential to minimize blue-water trade-offs between up- and downstream water users within the Amazon Basin.

We present a review of how transport and fate of micropollutants, i.e., pharmaceuticals and pesticides that are found in groundwater worldwide, can be studied using a laboratory setup of column experiments. Hereby, transport relevant processes are presented and which compounds and which of their properties can be studied with column experiments. We discuss advantages of this laboratory method and show weaknesses and problems.

The country of Myanmar and its abundant water resources are facing major challenges due to political and economic reforms, massive investments from neighbouring countries and climate change impacts. Publications on current and future impacts from human activities and climate change on Myanmar's river basins have been reviewed in order to gain an overview of the key drivers in these human–water dynamics. The review reveals the relevance of this information with regard to human–water interactions.

This paper reviews literature surrounding many aspects of socio-hydrological modelling; this includes a background to the subject of socio-hydrology, reasons why socio-hydrological modelling would be used, what is to be modelled in socio-hydrology and concepts that underpin this, as well as several modelling techniques and how they may be applied in socio-hydrology.

This review paper investigates the determinants of modelling choices for numerous applications of 1-D free-surface flow and morphodynamics in hydrology and hydraulics. Each case study has a signature composed of given contexts (spatiotemporal scales, flow typology, and phenomenology) and chosen concepts (refinement and subscales of the flow model). This review proposes a normative procedure possibly enriched by the community for a larger, comprehensive and updated image of modelling strategies.

This paper explores the benefits and advantages of R's usage in hydrology. We provide an overview of a typical hydrological workflow based on reproducible principles and packages for retrieval of hydro-meteorological data, spatial analysis, hydrological modelling, statistics, and the design of static and dynamic visualizations and documents. We discuss some of the challenges that arise when using R in hydrology as well as a roadmap for R’s future within the discipline.

The notion of a measure to quantify the degree of heterogeneity of a region from which information is required to estimate the magnitude of events at ungauged sites is introduced. These heterogeneity measures are needed to compare regions, evaluate the impact of particular sites, and rank the performance of delineating methods. A framework to define and assess their desirable properties is proposed. Several heterogeneity measures are presented and/or developed to be assessed, giving guidelines.

This article presents the most important facts on the life and scientific achievements of Steponas Kolupaila (1892–1964) – one of the most famous hydrologists of the 20th century. This Lithuanian scientist is especially well known for his book Bibliography of Hydrometry.

This paper present the results of interviews that were conducted with the developers of apps dedicated to avalanche risk communication. The study investigates the context of their development to determine how choices of content and visualization were made as well as how their effectiveness is evaluated. Results show that consensus is achieved in terms of message but not in terms of visualization. However, progress remains in terms of effectiveness evaluation.

This paper makes a rather exhaustive overview of current knowledge of past, current, and future aspects of cryospheric issues in continental Europe and makes a number of reflections of areas of uncertainty requiring more attention in both scientific and policy terms. The review paper is completed by a bibliography containing 350 recent references that will certainly be of value to scholars engaged in the fields of glacier, snow, and permafrost research.

We review what can be inferred about permafrost in the mountains of the Hindu Kush Himalaya region. This is important because the area of permafrost exceeds that of glaciers in this region. Climate change will produce diverse permafrost-related impacts on vegetation, water quality, geohazards, and livelihoods. To mitigate this, a better understanding of high-elevation permafrost in subtropical latitudes as well as the pathways connecting environmental change and human livelihoods, is needed.

In this study, TEC and positional variations have been examined seperately regarding the earthquake, which occurred in the Aegean Sea. Then The correlation of the said ionospheric variation with the positional variation has been investigated; it can be said definitely that it is a seismic origin anomaly; it is believed that upper air, geophysical, and geological data are required.

About 200 years ago in 1815 Sir James Hall made his famous analogue experiments, which showed probably for the first time that natural folds in ductile rock are the result of a horizontal compression. If such rocks are extended, then the rock layers can thin only locally, which is a process termed necking, and the resulting structure is often termed pinch-and-swell. We review here theoretical and experimental results on folding and necking on all geological scales.

The seismo-electromagnetic method is used for non-invasive subsurface exploration, showing interesting results for detecting fluids such as water, oil, gas, CO₂, or ice, and to better characterize the subsurface in terms of porosity, permeability, and fractures. We describe theoretical background, the role of key parameters, recent theoretical and numerical developments, and field and laboratory observations to show that this method can bring advantages compared to classical geophysical method.

This paper introduces a new method for mapping electric fields in the magnetosphere along geomagnetic field lines. This is important for conjugate studies of electric fields measured in the ionosphere by SuperDARN radars, and at spacecraft carrying electric field probes. First elementary methods in a dipole field are reviewed and then the theory of of a new method described for general magnetic field models. The method is tested in a dipole model with a Harris magnetotail field.

The method of electric field mapping along geomagnetic field lines, derived in an accompanying paper, is applied to the International Geomagnetic Reference Field. Formulae for the geomagnetic field gradient tensor are derived and these are used in a software package developed to map the electric field. A number of examples are presented illustrating the method. The method will be of importance in conjugate studies of ionospheric convection when the external magnetic field can be neglected.

A significant number of studies published over the last 15 years demonstrate that there is strong two-way coupling between the magnetosphere and ionosphere during geomagnetic activity; not only does the ionosphere respond to magnetospheric forcing during storms, but through its impact on wave generation, wave-particle interactions, ion outflow and mass loading at the dayside magnetopause and in the magnetotail, dense plasma plumes modulate the subsequent magnetospheric dynamics.

The behaviour of mirror mode waves in Venus's magnetosheath is investigated for solar minimum and maximum conditions. It is shown that the total observational rate of these waves does not change much; however, the distribution over the magnetosheath is significantly different, as well as the growth and decay of the waves during these different solar activity conditions.

The Radiation Assessment Detector (RAD), on board the Mars Science Laboratory (MSL) rover Curiosity, measures the energetic charged and neutral particles and the radiation dose rate on the surface of Mars. In this work we compare predicted electron/positron spectra with the signal measured by RAD. We find that the RAD electron/positron measurements agree well with the spectra predicted by Planetocosmics.

The solar wind magnetic field drapes around the active nucleus of comet 67P/CG, creating a magnetosphere. The solar wind density increases and with that the pressure, which compresses the magnetosphere, increasing the magnetic field strength near Rosetta. The higher solar wind density also creates more ionization through collisions with the gas from the comet. The new ions are picked-up by the magnetic field and generate mirror-mode waves, creating low-field high-density "bottles" near 67P/CG.

We have analysed the magnetic field measurements performed on the ROSETTA orbiter and the lander PHILAE during PHILAE's descent to comet 67P/Churyumov-Gerasimenko on 12 November 2014. We observed a new type of low-frequency wave with amplitudes of ~ 3 nT, frequencies of 20–50 mHz, wavelengths of ~ 300 km, and propagation velocities of ~ 6 km s⁻¹. The waves are generated in a ~ 100 km region around the comet a show a highly correlated behaviour, which could only be determined by two-point observations.

Galactic cosmic rays are high-energy particles from outside of the solar system. The products of their interaction with the atmosphere are counted by a network of neutron monitors. The number of cosmic rays reaching Earth is affected by the magnetic field embedded in the solar wind. The result is a number of regular variations in the neutron monitor data, including a diurnal variation. We have found that this variation is influenced by 1–2 h by the polarity of the Sun's magnetic field.

In situ spacecraft data in space plasma are obtained often as time series data. Using Taylor's frozen-in flow hypothesis, one can interpret the time series data as spatial variations swept by the slow and passing by the spacecraft. A quantitative method for estimating the error for Taylor's hypothesis is developed here.

The vast majority of shallow landslides and debris flows are precipitation initiated and predicted using historical landslides plotted versus observed precipitation information. However, this approach has severe limitations. This is partly due to the fact that it is not precipitation that initiates a landslide or debris flow but rather the hydrological dynamics in the soil and slope. We propose to include hydrological information in the regional hydro-meteorological hazard assessment.

Reliable information on the extent of climate change and its projected future impacts on transport infrastructure is of prime importance for the smooth functioning of societies. Rainfall events which may trigger landslides are analysed until the end of this century and compared to present-day conditions. Results indicate overall increases of landslide activity, especially in areas with structured terrain. Derived findings support proactive adaptation to rainfall-induced landslide exposure.

This study provides cross-discipline lessons for earthquake and flood vulnerability assessment methods by comparing indicators used in both fields. It appears that there is potential for improvement of these methods that can be obtained for both earthquake and flood vulnerability assessment indicators. This increased understanding is beneficial for both scientists as well as practitioners working with earthquake and/or flood vulnerability assessment methods.

Two established methods for assessing the physical vulnerability of buildings to natural hazards (vulnerability indicators and vulnerability curves) are compared after beind applied at the same case study. The case study area is located in South Tyrol (Italy) and it is subject to debris flow hazard. The results indicate that both methods have advantages and disadvantages and should be used in combination rather than in isolation by practitioners.

To help geo-scientists prepare for TV appearances, we review the scientific literature on effective science communication related to TV. We identify six main themes: scientist motivation, target audience, narratives and storytelling, jargon and information transfer, relationship between scientists and journalists, and stereotypes of scientists on TV. We provide a detailed case study as illustration for each theme.

Friedrich Robert Helmert died in Potsdam in 1917. He was, for over 30 years, director of the Royal Prussian Geodetic Institute and of the Central Bureau of the Internationale Erdmessung, today's IAG. He dedicated his life and his scientific career to the field of geodesy. His teachings on theoretical and physical geodesy were incorporated into university curricula around the world and hence into international endeavours to measure planet Earth.

Between 1880 and 1910 Elster and Geitel made important contributions to atmospheric electricity, in particular to precipitation electricity, the influence of solar radiation on the electric state of the atmosphere, the nature of charge carriers, and the ionization of air by radioactivity. They invented new instruments with unprecedented accuracy and reliability. A very modern concept was their attitude to undertake long-term measurements at various locations.

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