bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence-based conceptual requirements of regional groundwater processes for hydrological simulations
Authors: Oldham Louisa , Freer Jim , Coxon Gemma , Howden Nicholas , Bloomfield John , Jackson Christopher
Published: March 2020

River flows are the result of dynamically changing, interacting and non-linear processes of surface, near subsurface and often deeper groundwater flow from climatic drivers. Conceptual rainfall-runoff models, whilst providing advantages in computational efficiency and more minimal data requirements, often struggle to simulate contributions from groundwaters, resulting in poor model calibration. Improving predictions of river flows in these catchments is, however, critical to water resources planning and management, particularly in the UK where groundwater contributes 30% of public water supply in England. In order to improve model predictions in groundwater-dominated catchments, we conduct a detailed analysis of available observational data to better understand groundwater-surface water interactions and processes on a regional (aquifer) and local (river reach) scale, over geologically variable areas.

National meteorological, hydrological, hydrogeological, geological and artificial influence (characterising abstractions and return flows) datasets are used to develop a conceptualisation of the groundwater processes occurring in 99 subcatchments of the River Thames in the UK. We use these data to characterise the water balance, intercatchment groundwater flows, gaining/losing river reaches and hydrograph dynamics of these subcatchments, and investigate how dominant groundwater processes vary spatially and temporally. The River Thames has been selected as our case study owing to its wealth of data, densely gauged river network and geological variability.

We show that intercatchment groundwater flow is needed to ‘close’ the water balance in many catchments located on aquifer outcrops and find evidence of river-groundwater level flow thresholds. Importantly, we find that seasonality is a key control on the accurate representation of groundwater-surface water interaction processes and that the spatial and temporal variability of those processes varies greatly for different geologies across the Thames basin. We also demonstrate the importance of human influences to understand some of these spatial processes. We then identify the physical processes that existing conceptual rainfall-runoff models are likely missing, and what may be required to enable model calibration improvements in groundwater-dominated catchments.
The past and future of flow blocking around Greenland: connections between extremes
Authors: Barrett Bradford , Henderson Gina
Published: March 2020

Atmospheric flow blocking can be defined as a quasi-stationary center of high pressure that deflects traveling cyclones from their usual storm tracks. Over Greenland, flow blocking can result in a large-scale reversal of the meridional geopotential height gradient. Blocking often produces a strong equatorward deflection of polar air on the eastern flank of the anticyclone, and for Europe, blocking over or near Greenland can lead to severe cold episodes in winter and severe droughts and heat waves in summer. Moreover, because blocking is associated with an amplification of the meridional flow structure, it can be connected to extremes in poleward moisture transport. When these temperature and moisture extremes occur over Greenland itself, they exert significant stresses on the surface ice sheet. For these reasons, it is important to examine atmospheric blocking, both historically and in future climates.

There have been many metrics created to identify and quantify atmospheric flow blocking. Here, we use one such metric, the Greenland Blocking Index (GBI), to examine atmospheric flow blocking over and around Greenland and link that blocking to moisture transport. Moisture transport was calculated at each grid point in the ERA-Interim reanalysis using the integrated vapor transport (IVT) method applied between 200 and 1000 hPa. The GBI was calculated daily for the period 1948-present by averaging the 500-hPa height field in the NCEP/NCAR reanalysis over 80°E-20°E and 60°N-80°N. An IVT index was calculated from 1980-present by averaging IVT at each grid point over a North Atlantic region encompassing Greenland (85°E-15°E and 55°N-80°N). Both GBI and IVT were also examined in the historical NCAR CESM run of the Climate Model Intercomparison Project 6 (CMIP6), but over a much longer time record (1850-2015). In both datasets, extreme instances of blocking and IVT were examined at the 90th, 95th, 97th, and 99th percentiles, for both summer (JJA) and winter (DJF) seasons. Blocking frequency was found to increase in the latter half of the period in both datasets and over both time records. Moreover, a time lag was found between the instances of extreme blocking events and above-average IVT: high moisture transport more frequently preceeded instances of extreme blocking than lagged after it (by an average of 3 days). Implications of these results for Greenland ice mass balance will be explored in the presentation. 
Microcontrollers beyond Arduino: a stationary and a mobile environmental monitoring system
Authors: Beiter Daniel , Vetter Tobias , Morgner Markus , Seehaus Carlo , Schröder Stephan , Blume Theresa
Published: March 2020

In the course of the Helmholtz MOSES initiative two monitoring systems are being developed which consist of the same key components and thus functionality but with very different scopes of application. One is a stationary data logger with a classic measurement routine (on/off duty cycle) and support for various hardware interfaces (2xSDI12, 1xRS485, 2xUART, amongst others). The other is a drifting data logger that stays idle until a flood event activates the logger and carries it downstream. On-board are turbidity, EC and temperature sensors, a GPS and an inertial measurement unit (IMU) monitoring turbulence.

Advancements in electronics driven by automotive, mobile and IoT applications led to the development of very powerful, small and low power microcontrollers. This is why we decided to leave the realms of ATMega 8-bit systems (such as Arduino) and move towards ARM Cortex 32-bit systems. More precisely we used the Teensy 3.5 microcontroller development system as the core for the two systems. It is superior to Arduino in terms of performance while its developing team tries to maintain compatibility to Arduino in terms of programming vocabulary. This allows easier migration but comes also with restrictions regarding the capabilities of the hardware.
The other key component is the FiPy which supports five different wireless network types (WiFi, Bluetooth, LoRa, Sigfox, LTE-M) in one module. In comparison to most other hardware it runs MicroPython which adds more complexity to the project. Even though it is a microcontroller and features also several hardware interfaces, power consumption is far from low power, which is why it is used here only for remote communication and data transmission. In addition, several design decisions were made regarding power path routing and jumper configuration to improve the systems’ overall versatility, debugging capabilities and low power functionality, which are often key to the feasibility of a remote monitoring system.
LIDI 2 – New Evaluation Strategy for Accurate and Precise Clumped Isotope CO2 Analysis on Carbonate Samples
Authors: Mandic Magda , Tuthorn Mario , Stoebener Nils , Radke Jens , Schwieters Johannes
Published: March 2020

Long Integration Dual Inlet (LIDI) is an established technology which enabled improved accuracy and precision of Δ47 analysis from carbonate samples by utilizing sequential measurement of the full sample and reference, rather than alternating between sample and reference on shorter time periods, as it is done in the classical Dual Inlet method. As of today, there are two key challenges that were limiting further improvements to Δ47 determination: the IRMS must be in a stable temperature environment during long measurement of sample and reference gas, and the crimping of the sample and reference capillaries must be precisely matched, otherwise the produced data will be inaccurate and have reduced precision.

Here we present the improvements made on the sample gas measurement and data evaluation, which we define as LIDI 2.

By applying the LIDI 2 method, sample bracketing is possible following a four-step approach, resulting in fully corrected temperature drift (i.e. eliminated from the data), decreasing the standard deviation by factor of 2. This is a substantial improvement for acquiring clumped isotope data as reaching a very stable temperature of ±0.1°C/h is a challenge for most laboratories.

Alongside eliminating variation in the Δ47 data caused by unstable laboratory air temperature, LIDI 2 also improves the overlap of sample and reference gas signals due to non-perfect crimping of the capillaries. The crimping procedure is laborious and rarely delivers perfect results. Additionally, the pressure adjustment before reference measurement must ensure there is no significant offset between sample and reference intensities. LIDI 2 delivers perfect sample versus reference intensity matching, which results in significantly higher precision on each sample gas analyzed. Standard error of a single sample measurement is improved by up to factor of 2.

The LIDI 2 method delivers improved accuracy and precision on Δ47 measurement from small Carbonate samples, which in combination with the latest advancements in inert capillaries coating and automated contaminant trapping contributes to enhanced clumped isotopes data quality.

 
Estimating out-of-bank discharge uncertainties using a hydrodynamic model and nationally available datasets
Authors: Coxon Gemma , Milsom Robert , Neal Jeff
Published: March 2020

Robust predictions and forecasts of flood risks and hazards are reliant on accurate estimates of stream flow data.  However, the stage-discharge relationship is subject to substantial uncertainties from a range of error sources, particularly for out-of-bank flows where measurements are scarce and flows are often extrapolated.  Hydraulic modelling can be used to produce more reliable stage–discharge relationships beyond the range of observed measurements, but, these methods are often data intensive requiring topographical, bathymetric, calibration data etc. restricting their use across large samples of gauges.    

In this study, we present an automatable framework that can estimate out-of-bank discharge uncertainty using a hydrodynamic model and readily available national datasets.  The framework utilises LiDAR data, in-bank stage-discharge measurements and gauged river flows to calibrate a 1D/2D hydrodynamic model (LISFLOOD-FP) of a river reach and make predictions of river flow and rating curve uncertainty beyond bankfull.  A particularly novel aspect of this framework is the use of national LiDAR datasets of water surface elevation returns to estimate the bathymetry and friction in the channel using an inversion solver. 

The framework was applied to produce models of two gauged river reaches in the UK, the River Severn at Montford in Shropshire, and the River Tweed at Norham in Northumberland. Bathymetry estimates were consistent with observations, considering that the channel was simplified to rectangular below the LiDAR water surface, while Manning’s channel friction estimates were between 0.03 and 0.035. The model predictions showed a close fit to the official rating curve and out-of-bank stage-discharge measurements, with the model-predicted uncertainty bounds able to contain 89.5% and 100% of the out-of-bank flow measurements for Montford and Norham respectively. This holds promising results for quantifying out-of-bank discharge uncertainties across large samples of catchments to enable robust national flood risk assessment.
A Field-, GIS- and FTIR based approach to assess the distribution and development of soils affected by historical charcoal production in western Connecticut, USA
Authors: Bonhage Alexander , Hirsch Florian , Raab Thomas , Schneider Anna , Raab Alexandra , Ouimet William
Published: March 2020

The effects of historical charcoal production on forest soil properties are increasingly well studied on sites in Europe and the northern USA. The most obvious effect of this past forest use practice is the addition of large quantities of charcoal into the soil at sites of former charcoal production. These so called relict charcoal hearth (RCH) sites are mapped in expansive numbers due to the rising availability of high-resolution LiDAR data. However, studies determining the impact of RCHs on more than a field plot scale are rare, so far. To transform results from specific RCH sites to a landscape scale, we sampled and measured 52 RCH sites on a 0.7 km² area in the Litchfield Hills in western Connecticut, USA.

In this study we combine field based measurements of RCH site stratigraphy and geometry, GIS-based spatial analysis of site locations, laboratory determination of soil organic and pyrogenic carbon and FTIR-based analysis of soil carbon. We aim at assessing the soil distribution and soil development in an RCH affected landscape, i.e. the distribution of three typical soils commonly found in these landscapes: natural forest soils, technogenic soils of RCH platforms and soils buried below technogenic soils. Furthermore, we determine the distribution of organic and pyrogenic carbon in these soils and specifically the variation of carbon contents within the technogenic RCH soil stratigraphy.

Preliminary results suggest that RCH site occurrence does not depend on relief position, i.e. RCH site abundance is not correlated with slopes, plateau or flatland positions. However, RCHs with multiple layers of technogenic substrates are more abundant on slope positions. RCH soils have a significantly increased content in total carbon compared  to unaffected forest soils. Multi-layered RCHs have a heterogeneous vertical distribution of pyrogenic carbon and a possibly modern enrichment of organic matter in the surface soil. Wet chemical digestion of RCH soil samples coupled with FTIR analysis shows an increased presence of aromatic compounds and therefore pyrogenic carbon. However, the majority  of carbon in RCH soils seems to be of non-pyrogenic origin. As of now it is unclear, whether  the content of pyrogenic carbon is underestimated by analytical uncertainties or if pedogenic processes are responsible for an enrichment of labile- and semi-labile organic carbon in the charcoal-rich RCH soil.
Evaluating the skill of satellite data on the individuation of extreme precipitation events in Calabria (southern Italy)
Authors: Caloiero Tommaso , Coscarelli Roberto , Caroletti Giulio Nils
Published: March 2020

In this study, the skill of TRMM Multi-Satellite Precipitation Analysis (TMPA) data to locate spatially and temporally extreme precipitation has been tested over Calabria, a region in southern Italy.

Calabria is a very challenging region for hydrometeorology studies, as i) it is a mainly mountainous region with complex orography; ii) it is surrounded by sea, providing  an abundance of available moisture; iii) it belongs to the Mediterranean region, a hot-spot for climate change.

TMPA, which provides daily data at a 0.25° resolution (i.e., about 25 km at southern Italy latitudes), was tested with regards to three extreme precipitation events that occurred between 1998 and 2019, i.e., the years of TMPA’s operational time frame. The first event, taking place on 07-12/09/2000, lasted for several days and involved most of Calabria. The second (01-04/07/2006) was a very localized midsummer event, which hit a very small area with destructive consequences. Finally, the 18-27/11/2013 event was a ten-day long heavy precipitation event that hit the region in spots.

TMPA daily data were compared against validated and homogenized rain gauge data from 79 stations managed by the Multi-Risk Functional Centre of the Regional Agency for Environmental Protection. TMPA was evaluated both in relative and absolute terms: i) the relative skill was tested by checking if TMPA evaluated correctly the presence of extreme precipitation, defined as daily precipitation passing the 99th percentile threshold; ii) the absolute skill was tested by checking if TMPA reproduced correctly the cumulated precipitation values during the events.

TMPA proved sufficiently able to locate areas subject to heavy cumulated precipitation during large spatially distributed events over the region. However, it showed difficulties in reproducing very localized events, as the 2006 case study was not detected at all, showing that 25-km spatial resolution and daily time resolution proved inadequate to resolve this type of rainfall event.

Results might give insights into the possibility of using satellite data for real-time monitoring of extreme precipitation, especially since the transition from the old TMPA to the new Integrated Multi-satellitE Retrievals for GPM (IMERG) set was completed in January 2020.

 

Acknowledgments:

The Project INDECIS is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) with co-funding by the European Union (Grant 690462).
Dust impact detections by a set of Faraday cups in the lunar environments
Authors: Kononov Oleksii , Pavlů Jiří , Nouzák Libor , Šafránková Jana , Němeček Zdeněk , Přech Lubomír
Published: March 2020

The Bright Monitor of the Solar Wind (BMSW) for the Luna-Resurs-1 mission is an instrument designed for high-time (30 ms) resolution measurements of moments of the ion energy distribution by Faraday cups in the solar wind and in a plasma environment at altitudes between 65 and 150 km above the lunar surface. Previous studies performed by a similar instrument located on-board the Spektr-R spacecraft demonstrated a possibility to detect hypervelocity impacts of dust grains by such instruments Our analysis shows that the main problem of the reliable detection of dust impacts using such types of instruments is their sampling rate. In the paper, we present a novel design of a set of FCs that improves the ability of the dust detection using a simple identification algorithm that can store data with a higher sampling rate around the impact pulse. Moreover, we discuss a calibration of the detectors and their front-end electronics using the dust accelerator in order to find a relation between impact parameters and pulse heights.
Combining Ground-Penetrating Radar profiles with geomechanical and petrophysical in situ measurements to characterize sub-seismic resolution structural and diagenetic heterogeneities in porous sandstones (Northern Apennines, Italy)
Authors: Del Sole Leonardo , Calafato Antonino , Antonellini Marco
Published: March 2020

Deformation bands and structurally-related diagenetic heterogeneities, here named Structural Diagenetic Heterogeneities (SDH), have been recognized to affect subsurface fluid flow on a range of scales and potentially promoting reservoir compartmentalization, altering flow paths, influencing flow buffering, and sealing during production. Their impact on reservoir hydraulic properties depends on many factors, such as their permeability contrast with respect to the undeformed reservoir rock, their anisotropy, thickness, geometry as well as their physical connectivity and arrangement in the subsurface. Deformation bands offsets (from a few mm to 20-40 mm) and diagenetic heterogeneities (carbonate nodules) dimensions (from 0.2 to 15 m in length; from 0.1 to 1.0 m in thickness) make them SDH below seismic resolution.

We used Ground Penetrating Radar (GPR) for detection and analysis of the assemblage “deformation bands - carbonate nodules”, in high-porosity arkose sandstone of the Northern Apennines (Italy). Petrophysical (air-permeability) and mechanical (uniaxial compressive strength) properties of host rock, deformation bands, and calcite-cement nodules were evaluated along a 30-meters thick stratigraphic log to characterize the permeability and strength variations of those features. 2D GPR surveys allowed the description of the SDH spatial organization, geometry, and continuity in the subsurface. The assemblage “deformation bands – nodules” decreases porosity and permeability and produces a strengthening effect of the rock volume, inducing a strong mechanical and petrophysical heterogeneity to the pristine rock. Different textural, petrophysical, and geomechanical properties of deformation bands, nodules, and host rock result in different GPR response (dielectric permittivity; instantaneous attributes). We show that GPR can be useful to characterize variations in petrophysical and geomechanical properties other than characterize the geometry and spatial distribution of flow baffles and small-scale flow barriers in the subsurface such as deformation bands and cement-nodules. GPR showed its worth as a high-resolution and non-invasive tool to extend outcrop information (petrophysical and geomechanical data) to 3D subsurface volumes in a way to reconstruct realistic and detailed outcrop analogues. Such potential could be critical in assisting and improving the characterization of SDH networks in the study of faulted aquifers and reservoirs in porous sandstones.
Detection and Dynamic Imaging of Ocean Microplastics from Space
Authors: Ruf Christopher , Evans Madeline
Published: March 2020

Most ocean microplastic concentration data come from manta net trawling. Net trawling has a low sample rate that may be underestimating the true plastic concentrations. Plastic concentrations are also not well sampled outside the North Atlantic and North Pacific gyres. Ocean circulation models have been used to estimate the transport of plastics in the ocean and model predictions of their accumulation in ocean gyres have been validated to some degree by net trawl data. However, concentrations of plastic debris in close proximity can vary by orders of magnitude in the span of days, suggesting the presence of complex transport mechanisms and spatiotemporal variability that net trawl sampling and global circulation models may be unable to adequately resolve.

 

Attempts have been made to use spaceborne remote sensing methods to detect areas of high oceanic plastic concentrations. Methods based on hyperspectral imaging are being successfully explored, but their coverage and timeliness are limited. An alternate approach is presented here which provides more global, time resolved, coverage. Spaceborne radar measurements of ocean surface roughness are used to infer the reduction in responsiveness to wind-driven roughening caused by microplastics and surfactant tracers. On a global scale over long time periods, the reduction correlates strongly with the mass density of microplastics near the surface measured by net trawl campaigns and predicted by ocean circulation models. On a global scale on shorter time scales, time lapse images derived from the radar observations reveal seasonal changes in the microplastic mass density which appear to be related to seasonal ocean circulation patterns. On smaller spatial and temporal scales, time lapse images reveal episodic bursts of microplastic outflow from major river discharges into the sea.
The Data Assimilation Research Testbed: Nonlinear Algorithms and Novel Applications for Community Ensemble Data Assimilation
Authors: Anderson Jeffrey , Collins Nancy , El Gharamti Moha , Hoar Timothy , Raeder Kevin , Castruccio Frederic , LIang Jingjing , Lin John , McCreight James , Noh Seongjin , Raczka Brett , Arezoo Rfieeinasab Arezoo
Published: March 2020

The Data Assimilation Research Testbed (DART) is a community facility for ensemble data assimilation developed and maintained by the National Center for Atmospheric Research (NCAR). DART provides ensemble data assimilation capabilities for NCAR community earth system models and many other prediction models. It is straightforward to add interfaces for new models and new observations to DART.

DART provides traditional ensemble data assimilation algorithms that implicitly assume Gaussianity and linearity. Traditional algorithms can still work when these assumptions are violated. However, it is possible to greatly improve results by extending ensemble algorithms to explicitly account for aspects of nonlinearity and non-Gaussianity. Two new algorithms have been added to DART. 1). Anamorphosis transforms variables to make the assimilation problem more linear and Gaussian before transforming posterior estimates back to the original model variables; 2). The marginal correction rank histogram filter (MCRHF) directly represents arbitrary non-Gaussian distributions. These methods are particularly valuable for data assimilation for bounded quantities like tracers or streamflow.

DART is being applied to a number of novel applications. Examples in the poster include 1). An eddy-resolving global ocean ensemble reanalysis with the POP ocean model and an ensemble optimal interpolation; 2). The WRF-Hydro/DART system now includes a multi-parametric ensemble, anamorphosis, and spatially-correlated noise for the forcing fields. 3). Results from the Carbon Monitoring System over Mountains using CLM5 to assimilate remotely-sensed observations (LAI, biomass, and SIF) for a field site in Colorado; 4). Assimilation of MODIS snow cover fraction and daily GRACE total water storage data and its impact on soil moisture using the DART/NOAH-MP system. 5). An ensemble atmospheric reanalysis using the CAM general circulation model.
Linking the variability of PM10 in Europe to the position of the extratropical jet
Authors: Ordóñez Carlos , Garrido-Perez Jose M. , García-Herrera Ricardo , Barriopedro David
Published: March 2020

We have investigated the impact of the polar jet on the winter PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) concentrations in Europe during a 10-year period. For this purpose, we have computed the daily latitude and strength of the jet by using reanalysis wind fields in the lower troposphere over the eastern North Atlantic (0°–15° W). Then we have extracted daily average surface PM10 observations at ~440 sites from the European air quality database (AirBase).

Four preferred jet positions have been identified over the 0°–15° W sector in winter: southern (south of 41° N), central-southern (between 41° N and 51° N), central-northern (between 51° N and 63° N) and northern (north of 63° N). They exert a stronger influence than the jet strength on the mean PM10 levels. Consequently, we have examined whether the full distribution of PM10 and the occurrence of PM10 extremes (exceedances of the local winter 95th percentiles) are also linked to the jet position.

The northern position is associated with enhanced PM10 concentrations (on average ~9 μg m−3 above the mean values) and threefold increases in the odds of PM10 extremes over northwestern / central Europe. Comparable increases have been found in southern Europe when the jet is in its central-northern position. In both cases, the rise in the PM10 concentrations is associated with blocking of the zonal flow over those regions and the impact on PM10 extremes is maximised for time lags of around 1–2 days. On the other hand, the mean sea level pressure (SLP) patterns of the central-southern jet position resemble a positive phase of the winter North Atlantic Oscillation (NAO), yielding large PM10 decreases (on average around −9 μg m−3) in northwestern / central Europe. Similarly, the southern jet position results in low PM10 concentrations in southern Europe.

These results demonstrate that winter near-surface PM10 concentrations in Europe are strongly sensitive to the jet latitude, with implications for future projections of air pollution. As there is no consensus on the future evolution of the North Atlantic jet in a warming climate, different responses among model simulations could be relevant to understand discrepancies in their climate change projections of PM10 and other pollutants.
Dynamic Core of the MJO
Authors: Zhang Chidong , Kim Ji-Eun
Published: March 2020

This presentation introduces a theory in which the dynamic core of the MJO is described in terms of a harmonic oscillator that can be excited by stochastic forcing. The mechanism for selecting MJO scales comes from momentum damping. The resonant solution to the equation for a damped harmonic oscillator on an equatorial beta plane represents the equatorial Kelvin wave for small damping and large zonal wavenumbers and the MJO for large (3 – 5 days) damping and zonal wavenumber one. This theory demonstrates the distinction between the Kelvin wave and MJO and their continuous transition. In contrast to most other MJO theories that compete against each other, this theory embraces most other theories in that they provide possible sources of energy (forcing) to the dynamic core of the MJO.
Rapid intensification of tropical cyclones: Vortex waves seeded by aurorally-generated atmospheric gravity waves?
Authors: Nikitina Lidia , Prikryl Paul , Zhang Shun-Rong
Published: March 2020

Convective bursts have been linked to intensification of tropical cyclones [1]. We consider a possibility of convective bursts being triggered by aurorally-generated atmospheric gravity waves (AGWs) that may play a role in the intensification process of tropical cyclones [2]. A two-dimensional barotropic approximation is used to obtain asymptotic solutions representing propagation of vortex waves [3] launched in tropical cyclones by quasi-periodic convective bursts. The absorption of vortex waves by the mean flow and formation of the secondary eyewall lead to a process of an eyewall replacement cycle that is known to cause changes in tropical cyclone intensity [4]. Rapid intensification of hurricanes and typhoons from 1995-2018 is examined in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. In support of recently published results [2] it is shown that rapid intensification of TCs tend to follow arrival of high-speed solar wind when the MIA coupling is strongest. The coupling generates internal gravity waves in the atmosphere that propagate from the high-latitude lower thermosphere both upward and downward. In the lower atmosphere, they can be ducted [5] and reach tropical troposphere. Despite their significantly reduced amplitude, but subject to amplification upon over-reflection in the upper troposphere, these AGWs can trigger/release moist instabilities leading to convection and latent heat release. A possibility of initiation of convective bursts by aurorally generated AGWs is investigated. Cases of rapid intensification of recent tropical cyclones provide further evidence to support the published results [2].

References

[1] Steranka et al., Mon. Weather Rev., 114, 1539-1546, 1986.

[2] Prikryl et al., J. Atmos. Sol.-Terr. Phys., 2019.

[3] Nikitina L.V., Campbell L.J., Stud. Appl. Math., 135, 377–446, 2015.

[4] Willoughby H.E., et al., J. Atmos. Sci., 39, 395–411, 1982.

[5] Mayr H.G., et al., J. Geophys. Res., 89, 10929–10959, 1984.
On coupled dynamics and regime shifts in coupled human-water systems
Authors: Muneepeerakul Rachata , Homayounfar Mehran
Published: March 2020

To clarify the nonlinear and intertwined dynamics in coupled human-water systems, we developed a stylized model that combines simple hydrological and social dynamics. In this model, neither too much nor too little water is good (think floods and droughts, respectively; this is a feature absent in previous models) and the population self-organizes to respond to relative benefits they derive from the water system and outside opportunities. Despite its simplicity, the model richly yields 6 different regimes. A closer look at the conditions giving rise to these different regimes sheds light on the design of policies and adaptation strategies for the coupled human-water system under different social-hydrological settings. Advantages and limitations of this modeling approach will also be discussed.
Precipitation Associated with Cyclogenetic Hotspot Regions in the Extratropical Southern Hemisphere: CORDEX-CORE Projections
Authors: Reboita Michelle , Reale Marco , da Rocha Rosmeri , Giuliani Graziano , Coppola Erika , Nino Rosa , Llopart Marta , Torres Jose , Cavazos Tereza
Published: March 2020

Projections of the precipitation associated with cyclones in the main cyclogenetic regions of the Extratropical Southern Hemisphere domains (Africa - AFR, Australia - AUS and South America - SAM) are here analyzed during the winter season (JJA). The projections were obtained with the Regional Climate Model version 4 (RegCM4) nested in three global climate models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5) under the Representative Concentration Pathway 8.5. RegCM4 simulations were executed with horizontal grid spacing of 25 km and for the period 1979-2100. As reference period, we consider the interval 1995-2014 and as future climate, the period 2080-2099. Cyclones are identified using an algorithm based on the neighbor nearest approach applied to 6 hourly mean sea level pressure (SLP) fields. In SAM and AUS domains, two hotspot regions for cyclogenesis are selected while for AFR only one is considered. First, in each hotspot region, the cyclogeneses are identified and, then, the mean precipitation from the previous day (day-1) to the day after (day+1) of these processes is calculated. A general negative trend in the cyclone's frequency is projected for the period 2080-2099. However, for the same period, it is projected an increase of precipitation intensity for AFR domain, mainly near the southwestern coast of the continent. In AUS the increase is observed between southeastern Australia and New Zeland, and over north New Zealand. For SAM there is an expansion of the area with a maximum precipitation intensity close to southern Brazil and Uruguay and to the east of 60oW near 40oS. Summarizing, the precipitation associated with individual cyclones will increase on average in the future (for example 30% in the SAM domain), being the storms less frequent but more intense.
Land Surface Model influence on the simulated climatologies of extreme temperature and precipitation events within the WRF model over North America
Authors: García-García Almudena , Cuesta-Valero Francisco José , Beltrami Hugo , González-Rouco J. Fidel , García-Bustamante Elena , Finnis Joel
Published: March 2020

The representation and projection of extreme temperature and precipitation events in climate models are of major importance for developing polices to build communities’ resilience in the face of climate change. However, state-of-the-art global and regional climate model simulations yield a broad inter-model range of intensities, durations and frequencies of these extremes.

Here, we present a modeling experiment using the Weather Research and Forecasting (WRF) Regional Climate Model (RCM) to determine the influence of the choice of land surface model (LSM) component on the uncertainty in the simulation of extreme event statistics. First, we evaluate land-atmosphere interactions within four simulations performed with the WRF model coupled to three different LSMs from 1980 to 2012 over North America. Results show regional differences among simulations for the frequency of events when surface conditions are altered by atmospheric forcing or by land surface processes. Second, we find a large inter-model range of extreme statistics across the ensemble of WRF-LSM simulations. This is particularly the case for indices related to the intensity and duration of temperature and precipitation extremes.

Regions displaying large uncertainty in the WRF simulation of extreme events are also identified in a model ensemble experiment carried out with three different RCMs participating in the Coordinated Regional Climate Downscaling Experiment (CORDEX) project. This agreement between the model simulations performed in this work and the set of CORDEX simulations suggests that the implications of our results are valid for other model ensembles. This study illustrates the importance of supporting the development of new multi-LSM modeling studies to understand inter-model differences in simulating extreme events, ultimately helping to narrow down the range across climate model projections.
Disintegrated coastal zone management (DICZM): an example from Auckland, New Zealand
Authors: Brook Martin , Palma Alex , Garill Rosemary , Richards Nick , Tunnicliffe Jon
Published: March 2020

Typically, integrated coastal zone management (ICZM) uses the informed participation and cooperation of all stakeholders to assess the societal goals in a given coastal area. ICZM seeks, over the long term, to balance environmental, economic, social, cultural and recreational objectives, all within the limits set by natural dynamics. We outline coastal instability in the Auckland region of New Zealand, where the effects of natural coastal dynamics appear to have been underplayed, or even overlooked, during the residential land development process. Auckland is New Zealand’s largest city, with the Auckland region encompassing c. 3,300 km of coastline, with a highly variable wave climate and coastal geomorphology. The sparsely inhabited high energy west coast records significant wave heights of 2-3 m for much of the year. In contrast, the eastern bay coastlines are lee coasts, protected by offshore islands in the Hauraki Gulf and the Coromandel Peninsula. Nevertheless, significant coastal cliff instability does occur along these eastern coasts, which are heavily populated, with houses often constructed within 10 m of the cliff edge. Coastal instability in the Beachlands area in particular, is part-conditioned by engineering properties of the cliff materials, which include soft, Pleistocene sediments. In particular, shear surfaces develop along clay-rich tephra layers, which are of low-permeability, leading to increased porewater pressure, and cliff failure.  Despite the clear failure mechanisms, coastal protection works and routing of domestic stormwater over the cliffs has led to further coastal instability.
Effects of groundwater pumping on ground surface temperature: A regional modeling study in the North China Plain
Authors: Zhang You-Kuan , Yang Chen , Yang Xiaofan
Published: March 2020

It is recognized that groundwater (GW) may play an important role in the subsurface–land-surface–atmosphere system and that pumping of GW may affect soil moisture which in turn influences local weather and climate through land-atmosphere interactions. In this study effects of GW pumping on ground surface temperature (GST) in the North China Plain (NCP) were investigated with a coupled ParFlow.CLM model of subsurface and land-surface processes and their interactions. The model was validated using the water and energy fluxes reported in previous studies and from the JRA-55 reanalysis. Numerical experiments were designed to examine the impacts of GW pumping and irrigation on GST. Results show significant effects of GW pumping on GST in the NCP. Generally, the subsurface acts as a buffer to temporal variations in heat fluxes at the land-surface, but long-term pumping can gradually weaken this buffer, resulting in increases in the spatio-temporal variability of GST, as exemplified by hotter summers and colder winters. Considering that changes of water table depth (WTD) can significantly affect land surface heat fluxes when WTD ranges between 1–10 m, the 0.5 m/year increase of WTD simulated by the model due to pumping can continue to raise GST for about 20 years from the pre-pumping WTD in the NCP. The increase of GST is expected to be faster initially and gradually slow down. The findings from this study may implicate similar GST increases may occur in other regions with GW depletion.
Non-negligible regional differences in the driving forces of crop-related water footprint and virtual water flows: a case study for the Beijing-Tianjin-Hebei region
Authors: Li Meng , Zhuo La , Wu Pute
Published: March 2020

Water scarcity is a significant risk for meeting increasing food demand around the world. The importance of identifying the driving forces behind water consumption in agriculture and relative virtual water (VW) flows has been widely reported in order to provide practical advice for sustainable agricultural water resource management. However, the regional differences in the driving forces behind either water consumption or VW flows were largely ignored. To fill the crucial gap, taking nine major crops grown in the Beijing-Tianjin-Hebei (BTH) region in China over 2000-2013 as the study case, we investigate the regional differences in socio-economic driving forces on both the estimated water footprint (WF) in crop production and relative inter-city VW flows for each crop per year. Results show that although there is little change in total WFs in crop production (~43.3 billion m3/y on annual average), the WF per unit mass of crop decreased and the crop structure in the total WFs changed greatly. The BTH region was a VW importer with net VW import of 11.7 billion m3/y by 2013. The per capita GDP was the main positive driver of both total WFs of crop production and relative VW flows. Whereas the economic productivity and consumption ability were inhibiting factors for the WFs and VW flows, respectively. The levels of total crop WFs in agricultural cities were more sensitive to the effects of the main driving factors. The intensity of driving factors behind the inter-regional crop-related VW flows was shown to be directly related to the regional role as an importer or exporter. The current analysis suggests to develop characteristic agriculture considering the local role and regional differences in terms of water consumption and relative inter-regional VW flows, aiming for a balance between water sustainability, food security and economic developments.
Water exchange process and water uptake for irrigated maize cropland in a desert-oasis transition area, Northwest China
Authors: Zhang Yongyong , Zhao Wenzhi , Zhao Chun
Published: March 2020

Soil water and groundwater convert frequently under cropland in a desert-oasis transition area, Northwest China. Crops variedly utilize soil water and groundwater during different growth periods under the cropland with shallow groundwater. The study of water exchange process under irrigated cropland has important significance for regulating the contradiction between water saving and groundwater recharge in the desert-oasis transition area. Soil moisture and soil matric potential at depths ranging from 0 to 70 cm were measured using HydraProbe II and TEROS-21 soil sensors in maize (Zea mays L.) fields in 2019. Stable isotope (δ2H、δ18O) in different water sources (precipitation, irrigation water, soil water, crop stem, and groundwater) was also measured. The results showed that the groundwater depth varied between 0.57-1.07 m during the maize growth periods. The groundwater depth increased in summer due to the influence of pumped well, while the depth decreased in autumn resulting from the irrigation return water. In the maize growing season, soil moisture and water potential at depths from 10 cm to 30 cm responded to three irrigation times, while soil moisture and water potential below the depth of 50 cm were greater and kept a steady state, which were affected by upward capillary rise of groundwater. The relationship of soil water stable isotope values ​​was δ2H=2.45δ18O-31.41, which was lower than the slope of the local atmospheric precipitation line due to the evaporation effect. The soil water stable isotope values at depth of 10 cm varied, while the variation of soil water stable isotope values decreased with the increase of soil depth. The soil water stable isotope values at the depths from 70 to 90cm were close to the groundwater isotope values, which were affected by the groundwater. The stable isotope values in crop stem water were relatively scattered, indicating that the maize used multiple water sources and the water use strategy changed during the growth periods.
The Comparison of turbulent fluxes between a marsh wetland and a lake ecosystem
Authors: Du Qun , Liu huizhi , Liu yang , Xu lujun
Published: March 2020

Wetlands are “hot spot” area of global climate change, which are obviously sensitive to climate change. Under climate change, the carbon sequestration potential and carbon balance over wetland ecosystems are greatly altered, and large uncertainties are still existed in carbon budgets over these areas. Tengchong Beihai wetland is the only highland “floating blanket” lake wetland which is located in Southwest of China. As this land surface is composed by both water and terrestrial land surface, it’s doubted whether this type of wetland behaves more like lake or the latter one. Based on one year continuous observation measured with eddy covariance technique over Beihai wetland and Erhai Lake in 2016, the patterns of CO2 flux and energy fluxes over Tengchong wetland and Erhai lake are analyzed. The results show the diurnal variation of H and LE are both similar to Rn, which is different with Erhai lake. Erhai lake has a higher evaporation rate even in nighttime, which is much larger than Beihai wetland, due to the “floating blanket” vegetation could obviously reduce the evaporation rate. Beihai wetland acts as CO2 sink for the most time of the year, with an annual CO2 flux of -202.2 g C m-2, while Erhai Lake acted as CO2 source with an annual CO2 flux of 143.7 g C m-2. The results indicate the carbon and water exchange process in Beihai wetland behaves more like vegetated land surface.
The use of birch Betula pubescens folia morphology as indicator of atmosphere pollution and anthropogenic pressure
Authors: Sapunov Valentin
Published: March 2020

The increase of anthropogenic pressure and permanent pollution of the natural and urbanized environment requires the availability of effective methods for monitoring the ecological quality of territories. The priority should be considered simple, cheap and knowledge-intensive methods that can be owned by researchers without special environmental education. Such methods are the methods of phenogenetic indication and assessment of the morphological variability of widespread plants. Contaminants and pollutants can be divided into 4 categories: toxins, teratogens, carcinogens and mutagens. Toxins inhibit the development of organisms, but do not affect their genetic program. Teratogens disrupt the implementation of the genetic program. Mutagens and carcinogens destroy the genetic program itself, and these disorders can be passed on to the next generation. A convenient object of express monitoring is the birch Betula pubescens (alba) L, which is widespread in Eurasia. Toxic emissions destroy its growth and normal ontogenesis. The variability of the linear parameters of the leaves increases under environment stress. Teratogens increase the proportion of trees with dichotomy and trichotomy. The indicator of fluctuating asymmetry of leaves can serve as a criterion for mutagenic pollution of the environment. This paper presents estimates of morphological variability in different places of the Leningrad region. The coefficient of fluctuating asymmetry KA = (l1 - l2)2 / (l1 + l2) is introduced, where l1 and l2 are linear indicators of asymmetry. A high correlation was established between the level of diversity and the distance from the motorways and pollution by lead compounds, which is a teratogen. Fluctuating asymmetry is increased in places of radioactive contamination, depends on the distance to the trace of the Chernobyl disaster, the nuclear power plant. It is also increased in places of natural increased background radiation associated with the outputs of radioactive radon and the presence of granites. A map of the distribution of vegetation with varying degrees of morphological diversity and fluctuating asymmetry is presented. It is proposed to use the developed methods and algorithms for the assessment of toxic, teratogenic and mutagenic pollution of the environment and for the ecological monitoring of urbanized and non-urban areas.