bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Imaging of the Lithosphere beneath Arabian Shield and Implications for "Harrats" Volcanic Field
Authors: Sobh Mohamed , Zahran Khaled , Holzrichter Nils , Gerhards Christian
Published: March 2021

Widespread Cenozoic volcanisms in the Arabian shield including “Harrats” have been referring to lithospheric thinning and/or mantle plume activity as a result of Red Sea rift-related extension.

A fundamental key in understanding the deriving mechanism of these volcanic activities and its relationship to 2007-2009 seismic swarms required a reliable model of the present-day lithospheric thermo-chemical structure.

In this work, we modeled crustal and lithospheric thickness variation as well as the variations in thermal, composition, seismic velocity, and density of the lithosphere beneath the Arabian shield within a thermodynamically self - consistent framework.

The resulting thermal and density structures show large variations, revealing strong asymmetry between the Arabian shield and Arabian platform within the Arabian Plate.

We model negative density anomalies associated with the hot mantle beneath Harrats, which coincides with the modelled lithosphere thinned (~ 65 km) as a result of the second stage of lithospheric thinning following the initial Red Sea extension.
Color changes and dynamics of the third largest oval on Jupiter
Authors: Barrado-Izagirre Naiara , Legarreta Jon , Sánchez-Lavega Agustín , Pérez-Hoyos Santiago , Hueso Ricardo , Iñurrigarro Peio , Rojas Jose Felix , Mendikoa Iñigo , Ordoñez-Etxeberria Iñaki
Published: March 2021

Because of its large size, fast rotation and multiple atmospheric jets, Jupiter’s atmosphere holds a large variety of vortices. A large anticyclone at 19ºN planetographic latitude persists since at least 2006 after a complex dynamic history. This North Tropical Oval (NTrO) is located in the transition region between the North Equatorial Band (NEBn) and North Tropical Zone (NTrZ) and it is one of the longest-lived anticyclonic oval in the planet, following the Great Red Spot and oval BA. The region where it is located has a strong latitudinal shear, which allows the formation of dark cyclones and usually white anticyclones that stay stable in latitude. The NTrO has survived for years after mergers and disturbances: in February 2013, it merged with another oval and some months later, in September 2013, its color changed from white to red and then, in December 2014, back to white with an external red ring. The oval also survived the North Temperate Belt Disturbance (October 2016) which fully covered the oval, leaving it unobservable for a short time. It reappeared at its expected longitude as a white large oval keeping the same color and morphology from 2017 to 2020. Using JunoCam, Hubble Space Telescope (HST) and PlanetCam-UPV/EHU multi-wavelength observations, we describe the historic evolution of this oval’s properties. We used JunoCam and HST images to measure its size and its internal rotation obtaining a mean value of (10,500±1,000) x (5,800±600) km for the size and a mean relative vorticity of -(2±1)·10-5s-1. Contrarily to GRS and BA, which have higher vorticity values than their surroundings, the NTrO’s vorticity is nearly the same as the ambient vorticity of the area, which suggests that this oval is probably sustained by the zonal jets confining it. We also used HST and PlanetCam observations to characterize its color changes. The color and the altitude-opacity indices show that the oval is higher and has redder clouds than its environment but has lower cloud tops than other large ovals like the GRS, and it is less red than the GRS and oval BA. Despite the changes, mergers and disturbances experienced by the oval, its main characteristics remain unaltered and this suggests a vertically extended vortex with properties that could be related with the atmospheric dynamics below the observable cloud deck.
Budyko-Sellers 2.0: the classical and fractional heat equations, and the fractional energy balance equation
Authors: Lovejoy Shaun
Published: March 2021

The highly successful Budyko-Sellers energy balance models are based on the classical continuum mechanics heat equation in two spatial dimensions. When extended to the third dimension using the correct conductive-radiative surface boundary conditions, we show that surface temperature anomalies obey the (nonclassical) Half-order energy balance equation (HEBE, with exponent H = ½) implying heat is stored in the subsurface with long memory. 

 

Empirically, we find that both internal variability and the forced response to external variability are compatible with H ≈ 0.4.  Although already close to the HEBE and classical continuum mechanics, we argue that an even more realistic “effective media” macroweather model is a generalization: the fractional heat equation (FHE) for long-time (e.g. monthly scale anomalies).  This model retains standard diffusive and advective heat transport but generalize the (temporal) storage term.  A consequence of the FHE is that the surface temperature obeys the Fractional EBE (FEBE), generalizing the HEBE to 0< H ≤1.  We show how the resulting FEBE can be been used for monthly and seasonal forecasts as well as for multidecadal climate projections.  We argue that it can also be used for understanding and modelling past climates.
Cryogenic cave carbonates in the Dolomites (Northern Italy): insights into Younger Dryas cooling and seasonal precipitation
Authors: Koltai Gabriella , Spötl Christoph , Jarosch Alexander H. , Cheng Hai
Published: March 2021

In the European Alps, the Younger Dryas (YD) was characterized by the last major glacier advance with equilibrium line altitudes being ~220 to 290 m lower than during the Little Ice Age and also by the development of rock glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties leading to considerable ambiguities on the internal structure of this stadial, the most intensively studied one of the last glacial period.

Our study utilizes a novel paleoclimate archive, coarse crystalline cryogenic cave carbonates (hereafter CCC), that allows to precisely constrain when ~ 0°C conditions prevailed in the shallow subsurface in the past, often related to permafrost thawing events.

Here we presents the first record of CCC from the Dolomites (Southern Alps). In contrast to many studies from Central European caves these speleothems formed not during a major climate warming but within a prominent stadial. 230Th-dating of the CCC indicates sustained negative temperatures close to  ~0°C between ~12.6 and ~12.2 ka BP at about 50 m below the surface, initiating the slow freezing of dripwater-induced meltwater pockets in perennial cave ice. This in combination with thermal modelling argues for a cooling of ≤ 3°C at the Allerød-YD transition at this high-alpine site in the Southern Alps. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in a stable winter snow cover at this site. The snow cover insulated the subsurface and allowed the cave interior to remain close to the freezing point (0°C) year-round, promoting CCC formation.

The main phase of CCC precipitation at ~12.2 ka BP coincides with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ~12.2 ka BP was most likely associated with a slight warming of approximately +1°C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this alpine cave as well as ice glacier retreat and rock glacier expansion in the Alps. Our study demonstrates that CCCs can provide quantitative constraints on paleotemperature and seasonally resolved precipitation changes.
Diagnostic evaluation of runoff into the Arctic Ocean and its impact on freshwater transport through Arctic gateways.
Authors: Winkelbauer Susanna , Mayer Michael , Haimberger Leopold
Published: March 2021

Rapid surface warming in the Arctic region has strong impacts on the Arctic water balance and its individual hydrological components. With the Arctic Ocean being almost entirely surrounded by landmasses and some of the world’s largest rivers draining into it, the link between ocean and surrounding land is remarkably strong. Hence runoff forms one of the key variables in the Arctic freshwater budget and builds the main focus of this study.

Seasonal cycles, as well as annual and seasonal runoff trends are analyzed for the major Arctic watersheds. We first compare river discharge data taken from the reanalysis component from the Global Flood and Awareness System (GloFAS) to available observed river discharge records. GloFAS combines the land surface model from ECMWF’s most recent reanalysis effort ERA5 with a hydrological and channel routing model. Results show that seasonal river discharge peaks are underestimated by GloFAS as well as by direct ERA5 runoff.

Further analysis shows that this discrepancy can be tracked to non-stationary biases in the snow analysis of ERA5, which affect melt and subsequently runoff (Zsoter et al. (2020), https://doi.org/10.21957/p9jrh0xp). It is shown that this bias is substantially improved in ERA5’s downscaled counterpart ERA5-Land. An experimental version of GloFAS that uses ERA5-Land forcing, exhibits improved river discharge values.

Seasonal cycles of ERA5 snow melt show that there is a lag of 1-2 months between the peak in snow melt and observed river discharge, which can be explained by the time it takes for the water to reach the river mouth, but it may also be influenced by water resources management (e.g., Yang et al. (2004), https://doi.org/10.1016/j.jhydrol.2004.03.017 ; Ye et al. (2003), https://doi.org/10.1029/2003WR001991).

In addition, runoff is calculated over the whole pan-arctic region to account for the total freshwater entering the Arctic Ocean from land. Independent mooring-derived estimates of net freshwater flux through the Arctic oceanic gateways show a consistent and strong imprint of the runoff seasonal cycle.
Lightweight aggregates to reduce heavy metal pollution in green infrastructure for urban stormwater management
Authors: Pla Concepcion , Valdes-Abellan Javier , Pardo Miguel Angel , Moya-Llamas Maria Jose , Benavente David
Published: March 2021

The impervious nature of urban areas is mostly responsible for urban flooding, runoff water pollution and the interception of groundwater recharge. Green infrastructure and sustainable urban drainage systems combine natural and artificial measures to mitigate the abovementioned problems, improving stormwater management and simultaneously increasing the environmental values of urban areas. The actual rate of urban growth in many urban areas requires the enhancement and optimization of stormwater management infrastructures to integrate the territorial development with the natural processes. Regarding the quality of runoff stormwater, heavy metals are critical for their impact on human health and ecological systems, even more if we consider the cumulative effect that they produce on biota. Thus, innovative stormwater management approaches must consider new solutions to deal with heavy metal pollution problems caused by runoff. In this study, we propose the employment of Arlita® and Filtralite®, two kind of lightweight aggregates obtained from expanded clays, to remove heavy metal concentration from runoff stormwater. Laboratory experiments were developed to evaluate the removal rate of different heavy metals existent in runoff stormwater. The lightweight aggregates acted as filter materials in column experiments to quantify their removal capacity. In addition, batch tests were also developed to evaluate the exhaustive capacity of the materials. Results from the study confirmed the efficiency of the selected lightweight aggregates to reduce the heavy metals concentration by up to 90% in urban stormwater runoff.
A Geothermal Energy Concept based on Heat Storage in Geological Media
Authors: Vidal Rubén , Saaltink Maarten W. , Olivella Sebastià
Published: March 2021

Aquifer Thermal Energy Storage (ATES) can help to balance energy demand and supply to make better use of infrastructures and resources. ATES consists of a pair or more wells that simultaneously inject or extract thermal energy into aquifers. The aim of ATES is to store the excess of energy during summer and to reuse it during winter, when there is an energy deficit. High-temperature Aquifer Thermal Energy Storage (HT-ATES) provides a good option to store water over 50°C, but it requires facing some problems, such as low efficiency recoveries and the uplift of the surface. Coupled thermo-hydro-mechanical (THM) modelling is a good tool to analyze the viability and cost effectiveness of the HT-ATES systems and understand the interaction of processes, such as heat flux, groundwater flow and ground deformation. We present the 3D THM modelling of a pilot HT-ATES system, inspired by one of the projects of HEATSTORE, which is a GEOTHERMICA ERA-NET co-funded project. The model aims to simulate the injection of hot water of 90°C in a central well and the extraction of water in four auxiliary wells during summer. In winter, the auxiliary wells inject water of 50°C and the central well extract water. The loading lasts longer than the unloading (8 months versus 4 months) and overall more heat is injected than extracted. We found that the system is more efficient in terms of energy recovery, the more years the system is operating. In the aquifer, both thermal loads and hydraulic loads have an important role in terms of displacements. At the surface, the vertical displacements are only a consequence of the hydraulic strains generated by the injection of water in the aquifer.
Going beyond the one-off: How can STEM engagement programmes with young people have real lasting impact?
Authors: Archer Martin , DeWitt Jennifer , Davenport Carol , Keenan Olivia , Coghill Lorraine , Christodoulou Anna , Durbin Samantha , Campbell Heather , Hou Lewis
Published: March 2021

A major focus in the STEM public engagement sector concerns engaging with young people, typically through schools. The aims of these interventions are often to positively affect students’ aspirations towards continuing STEM education and ultimately into STEM-related careers. Most schools engagement activities take the form of short one-off interventions that, while able to achieve positive outcomes, are limited in the extent to which they can have lasting impacts on aspirations. We review various different emerging programmes of repeated interventions with young people, assessing what impacts can realistically be expected. Short series of interventions appear also to suffer some limitations in the types of impacts achievable. However, deeper programmes that interact with both young people and those that influence them over significant periods of time (months to years) seem to be more effective in influencing aspirations. We discuss how developing a Theory of Change and considering young people’s wider learning ecologies are required in enabling lasting impacts in a range of areas.
Joint interpretation of macroseismic and strong motion data for recent large shallow mainshocks of the Aegean area using a Monte Carlo optimization of finite-fault stochastic simulations
Authors: Ravnalis Michail , Kkallas Charalampos , Papazachos Constantinos , Margaris Basil , Papaioannou Christos
Published: March 2021

The study of strong historical and early instrumental earthquakes is based almost exclusively on the use of their macroseismic data, which usually constrain the area that has suffered the heaviest damage. In the recent decades, strong-motion data have been also employed for the same purpose. We present a stochastic simulation approach to jointly model macroseismic and strong motion data for selected shallow strong (M≥6.0) earthquakes that occurred in the broader Aegean region between 1978 and 1995. For the simulations we employed the finite-fault stochastic simulation method, as realized by the EXSIM algorithm. We calibrated several parameters for the stochastic simulation modeling using a priori published information (e.g., moment magnitude, stress parameter). Other rupture zone information were collected from published works, such as fault plane solutions, relocated seismicity, etc. A Monte Carlo approach was adopted to perform a parametric search for the stress parameter and the modelling both independently and jointly the available macroseismic data and the strong motion instrumental recordings. The validity and the reliability of this semi-automated simulation approach was examined, to test if this method could be applied either in a fully automated manner, or for the study of the source properties of historical earthquakes. The results suggest that a joint-misfit minimization from the simultaneous simulation of macroseismic and strong motion data is a feasible target, that can be potentially employed for the simulation of older events, for which a limited number of instrumental data is often available. In general, a good agreement of the spatial distribution of the original and modeled macroseismic intensities is observed, showing that can reliably reconstruct the main features of the damage distribution for strong shallow mainshocks in the Aegean area using the proposed joint interpretation approach.
Peat-based record from southern Patagonia shows centennial-scale variability since 4.2 ka
Authors: Loisel Julie , Sarna Kristen
Published: March 2021

Here we present a 4200-year-old high-resolution peat core reconstruction from southern Patagonia. Our detailed carbon isotope (δ13C) record and testate amoeba-inferred water table depth reconstruction point to a progressive wetting of the peatland surface from 4200 to 1500 cal. yr BP, followed by a dry event at 1200-800 cal. yr BP and drier conditions since then. Superimposed on this trend are centennial-scale dips in δ13C values and water table depths that we associate with warm/dry spells. We interpret these shifts, which are akin to positive phases of the Southern Annual Mode (SAM), as reflecting century-scale changes in the Southern Westerly Wind belt during the late Holocene. Other records from southern South America and Tasmania have revealed synchronous changes in local vegetation and fire activity, strengthening our hypothesis. We know that millennial-scale shifts in the Westerly winds influence ocean upwelling in the Southern Ocean, with effects on global atmospheric carbon dioxide (CO2) concentrations. Our study, along with a few others, may help elucidate whether centennial-scale SAM-like shifts could also modulate the global carbon cycle via CO2 degassing from the deep ocean. This is important because instrumental and reanalysis records indicate strengthening and poleward contraction indicate a positive phase of the SAM since the late twentieth century.
Spatiotemporal Variations in West Texas Playa Wetlands Mapped from Sentinel-2
Authors: Tripp Hannah , Crosman Erik
Published: March 2021

The improved spatial, spectral, and temporal resolution of Sentinel-2 satellite imagery compared to widely used Landsat imagery allows for many small, variable bodies of water such as intermittent rivers, glacial lakes, rice paddies, and ephemeral wetlands to be studied in depth for the first time.  Across the Texas High Plains, USA, playa lakes are highly sensitive to wet/dry cycles, and are noted for their critical ecological importance in the region, providing habitat for many species of birds and other animals. The playas are also known to be important features for aquifer recharge in some areas. While sporadic aircraft studies and satellite evaluations of the larger playas in the region have been conducted previously from Landsat, no known study has utilized the improved capabilities of Sentinel-2 imagery to document the numerous smaller playas in the region. In this study, we analyze playa lakes across northwestern Texas, USA between 2016-2020  using high-resolution spectral satellite imagery from the European Space Agency’s Sentinel-2 mission. The Semi-Automatic Classification plugin for QGIS is used to document spatial and temporal changes in the areal extent of water in seasonal playa lakes in the High Plains region of Texas. Several case studies of the spatial and temporal evolution of the playa lakes from Sentinel-2 imagery will be presented, as well as applications for seasonal ecological monitoring and groundwater recharge monitoring.   Images taken of the same playa lakes at different times are compared to determine the rate at which the amount of water is changing. Using data from the nearest available weather stations, the amount of water loss due to evaporation is estimated. This is compared to the observed water loss to estimate the amount of water percolating into the ground where it may be contributing to aquifer recharge. This study aims to be a proof of concept for a method for operationally monitoring the state of playa lakes across the region for ecological applications, as well as to quantify potential groundwater recharge.
The promise and limitations of improved-accuracy gravity field measurements for Uranus and Neptune
Authors: Movshovitz Naor , Fortney Jonathan
Published: March 2021

Uranus and Neptune present unique challenges to planetary modelers. The
composition of the so-called ice giants is very uncertain, even more so than the
composition of the gas giants. For instance, it is far from clear that either
planet's composition is dominated by water. Instead, the composition of Uranus and
Neptune likely includes water and other refractory elements in large quantities as
well as a substantial H/He envelope. Furthermore, formation models also predict
that composition gradients are likely in the interiors of these planets, rather
than a neat differentiation into layers of homogeneous composition. (See Helled
and Fortney 2020 and references within.)

A key question that impacts the science case for a potential orbiting mission to
Uranus or Neptune is how will more precise measurements of the gravitational field
better constrain either planet's interior density profile and composition.
Surprisingly, there is yet no published answer to this question.  Here, we present
new work that explores this issue, using a Bayesian framework that allows
exploration of a wide range of interior density profiles.

Our approach, which builds off our previous work for Saturn (Movshovitz et al.,
2020) and that of others  (e.g. Marley et al., 1995, Helled et al., 2011) takes a
relatively unbiased view of the interior structure by employing so-called
empirical density profiles. A parameterization is applied to the density profiles
directly (via mathematical base functions) instead of to an assumed layered
composition (H/He, water, rocks). While some of these empirical density profiles
may imply unrealistic compositions, they can also probe solutions that would be
missed by the standard layered-composition approach.

Here we will present models of Uranus and Neptune constructed with this approach,
and ask two questions: 1) How large is the space of possible solutions today? 2)
How much will it be reduced should a future mission to Uranus and Neptune improve
the precision on their gravity field measurements by several orders of magnitude,
to the level now available for Jupiter and Saturn?
Assessing the Influence of Topography and Environmental Factors on Gamma-Ray Air Dose Rates Under Canopies 
Authors: Yasumiishi Misa , Nishimura Taku , Aldstadt Jared , Masoudi Pedram
Published: March 2021

Researchers have measured aerial gamma-rays using remote measurement devices to estimate the radionuclide concentrations in soils. However, an issue arises when measuring air dose rates in forested areas, where canopies exist between the remote sensing device and the ground. When researchers do the reverse conversion from soil contamination levels to the air dose rates, the conversion formula is derived by assuming a flat ground surface (Jacob et al., 1994; Saito and Jacob, 1998); however, topography in forested areas is often not flat. This study examines the relationships among the air dose rates under the canopies, topography, and the soil contamination levels on forested hillslopes in Fukushima, Japan. Gamma-ray air dose rates were measured using a hand-held scintillator during the summer of 2018 (two days), and in the winter of 2019 using KURAMA, a portable scintillator carried in a backpack (one day). This study employed numerical methods, including semivariogram and R's CAR (Companion to Applied Regression) package, to find aerial gamma-ray activities' spatial structure and the optimal combinations of topographic predictors. The survey routes and soil sampling points did not coincide completely. Thus, spatial and temporal reorganizations and re-definitions of the spatial boundary to incorporate the air (boundaryless mass), topography (three-dimensional structure), and soil samples (point measurements) were needed to overcome data analysis challenges. Some preliminary results show that the median air dose rate on a summer day with stronger winds (wind speed 7.1 m/s) was closer to the one on a winter day than to the median on the other summer day with calm air. Distance dependency (semivariogram range) on the windy summer day and the winter day was 30 to 60 m. Distance dependency on a summer day with calm air was much longer, > 500 m. The aerial gamma-ray levels were not in a linear relationship with the elevation. Meanwhile, the areas under evergreen trees showed higher air dose rates (3-8 %) than the areas under deciduous trees in absolute measurements. However, the differences were not statistically significant. The combination of slope degrees, hillslope aspects, and curvature or upslope distance best described the air dose rates, depending on the survey routes, although their predictabilities (R2) were low, 0.35 at the most. The air dose rates, which were estimated from soil samples' effective relaxation mass depths, did not correlate with the actual air dose measurements, but this result is under further investigation. This study's complete results will provide additional consideration points to the gamma-ray air dose vs. soil contamination assessment in the forested areas.
Drivers of the Spatial Pattern of Arctic Sea Ice Response to Arctic Cyclones
Authors: Clancy Robin , Bitz Cecilia , Blanchard-Wrigglesworth Ed , McGraw Marie
Published: March 2021

The effects of Arctic cyclones on sea ice are the subject of many papers, however aside from individual case studies, few address the heterogeneity in the spatial pattern of the sea ice response.

We composite atmospheric conditions from ERA5 reanalysis and satellite sea ice concentrations on Arctic cyclones using a storm-centered approach to reveal the typical atmosphere and sea ice responses at different bearings and distances relative to an Arctic cyclone.

Asymmetry in the pattern of the sea ice concentration response to cyclones is revealed, with increased growth/reduced melt to the west of cyclones and decreased growth/increased melt to the east.

In part, this is explained by heterogeneity in the spatial patterns of atmospheric temperature and cloud fraction associated with cyclones, which result in heterogeneity in patterns of the surface energy fluxes.

Using the CICE sea ice model forced with prescribed atmospheric reanalysis from the Japan Meteorological Agency, we reveal the relative importance of the dynamic and thermodynamic forcing of cyclones on sea ice, as well as the spatial patterns of each. The dynamic and thermodynamic responses of sea ice concentration to cyclones are comparable in magnitude, however dynamic processes dominate the response of sea ice thickness.

These results highlight and explain important details often missed when answering “do cyclones cause an increase or decrease sea ice?”, as it appears the answer is both.
Seismic oceanography study of a mode-2 internal solitary wave in the northeast South China Sea
Authors: Kuang Yunyan , Song Haibin , Guan Yongxian , Fan Wenhao , Gong Yi
Published: March 2021

The nonlinear internal solitary waves (ISWs) are ubiquitous and recently many mode-1 ISWs have been reported to be detected in the northeast South China Sea by using the seismic oceanography method. However, few mode-2 ISWs are discovered in seismic data in the South China Sea. Thus, waveform characteristics and kinematics parameters of the mode-2 ISWs in this region need further study.

In this paper, one convex mode-2 ISW is presented near Dongsha Plateau on September 20th, 2009, and is analyzed by the combination of reprocessed seismic section and reanalysis hydrographic data. The seismic events of the multi-channel seismic section are extracted to obtain the vertical amplitude distribution and water depth of the mode-2 ISW. The seismic events can be used to analyze the structural characteristics in a snapshot, while different pre-stack common-offset gathers (COGs) can observe the seismic fine structures of the mode-2 ISW in chronological order. Furthermore, we use COGs method to calculate the apparent phase velocities of the peak and trough part of the mode-2 ISW on the seismic section and then correct the phase velocities according to the seismic measurement direction and ISWs propagation direction derived from satellite data. Theoretically, the reanalysis hydrographic data can be used to calculate the vertical structure and propagation speed of ISW based on the KdV model, and the theoretical results can be compared with those from seismic observations.

In total, 10 seismic events are extracted to obtain wave amplitudes and corresponding water depth distribution. Among the seismic events, only 2 events are elevation wave types and the rest 8 events are depression wave types. The maximum amplitude is about 25.5m of a depression wave event at 200m water depth. The dimensionless amplitude is 2.56, this number shows that the mode-2 ISW is of large amplitude. Moreover, the pycnocline is displaced over 20% from the mid-depth of the total seawater depth, illustrating the mode-2 ISW is of asymmetry. The fine structures of the mode-2 ISW observed on COGs also show the asymmetric and complex wave disturbance in different acquisition times. The apparent phase velocity of the crest is 1.59m/s, while the apparent phase velocity of the trough (the maximum amplitude) is 0.8065, the results indicate that the elevation waves of the mode-2 ISW may move faster than the underlying depression waves. Finally, the corrected phase speed of the mode-2 ISW is consistent with the propagation speed calculated by the KdV equation. More pieces of evidence are needed to explain the generation and to predict further evolution of the asymmetric mode-2 ISW, and seismic oceanography may be one of the key techniques to answer these questions.
A modified MOD16 algorithm to estimate soil evaporation and vegetation transpiration in urban garden area
Authors: Zhang Jiawei , Chen Han , Huang Jinhui Jeanne , McBean Edward , Li Han , Lan Zhiqing , Gao Jun Jie
Published: March 2021

Accurately estimate and map soil evaporation (E) and vegetation transpiration (T) in urban woodland areas is great significance for precision irrigation, urban water resource allocation and management. However, customized dual-source models based on satellite imagery are lacking. This research, for the first time, developed a dual source approach to predict E and T in urban garden area. The method is improved from MOD16 algorithm, we advanced the MOD16 in following aspects: 1, an enhanced net radiant flux (Rn) and soil heat flux (G) calculation method is proposed; 2, The determination of vegetation canopy impedance couples into the impact of carbon dioxide emissions; 3, A physical mechanism-based β estimation method is proposed, to replace the empirical values in original model. Our model was test in 40 cloudless days based on 10 m Sentinel-2 imagery in Guiwan Garden area in Shenzhen city, southern of China. The Shuttleworth-Wallace, FAO-dual-Kc and Priestley-Taylor model were used to evaluate model performance, results suggest the modified MOD16 model successful produce and partition ET in city garden area, and outperformed than pervious MOD16 algorithm. The spatial distribution pattern demonstrate that E and T present obvious seasonal changes, with the range of 23-150 W/m2 for E and 31-186 W/m2 for T, proven the large amount water was lost through ET in urban garden area. Sensitivity analysis results show that the improved MOD16 model is more sensitive to vegetation index products and solar radiation, need to prioritize the accurate input of these two types of parameters. The modified MOD16 model significantly facilitate the accuracy of ET simulation in high-resolution, small-scale areas, provides a powerful tool to quantify the E and T in urban areas, and assessing the impact of climate change on the urban hydrological cycle.
Anthropogenic aerosols modulated twentieth-century Sahel rainfall variability via impacts on North Atlantic sea surface temperature
Authors: Zhang Shipeng , Stier Philip , Dagan Guy , Wang Minghuai
Published: March 2021

Sahel rainfall experienced significant multidecadal variability over the twentieth century. Previous work have proposed several drivers to explain the severe drought and the subsequent recovery of Sahel rainfall in the past century, including anthropogenic aerosols, GHGs, and internal variabilities. However, the attribution remained ambiguous. Sahel summertime monsoon has close teleconnections with North Atlantic sea surface temperature (NASST) variability, which has been proven to be affected by aerosols. Therefore, changes in regional aerosols emission can potentially drive multidecadal Sahel rainfall variability.

Here we use ensembles of state-of-the-art global climate models (the CESM-large ensemble and CMIP6 models) and observational datasets to demonstrate that anthropogenic aerosols have significant impacts on twentieth-century Sahel rainfall multidecadal variability through modifying NASST. Aerosol-induced multidecadal variations of downward solar fluxes over the North Atlantic Ocean cause NASST variability during the 20th century, altering the strength of the Hadley cell and the ITCZ position, therefore, dynamically linking aerosol effects to Sahel rainfall variability. While the observed linear trend of NASST might still be affected by a mix of various external and internal drivers, our results suggest that NASST variability is most likely caused by aerosol-induced changes in radiative fluxes rather than changes in ocean circulations, and that anthropogenic aerosols can explain most of the detrended Sahel rainfall variability. CMIP6 models further suggest that aerosol-cloud interactions contributed more to the variability than aerosol-radiation interactions. These findings highlight the importance of accurate representation of regional aerosol radiative effects for the simulation of Sahel rainfall variability.
The effect of grain size reduction for the origin of the mid-lithosphere discontinuity
Authors: Liu Mingqi , Gerya Taras , Chen Ling
Published: March 2021

In the last decades, the high heterogeneity of lithospheric mantle in term of its physical properties and chemical compositions is widely documented by geophysical, petrological, and geochemical studies. A sharp discontinuity in seismic velocity (~2-10% reduction over no more than 30-40 km) is detected at 60 – 160 km depth in the continental lithosphere and at an average depth of 70 km in the oceanic lithosphere. Several models have been proposed for the genesis of this mid-lithosphere discontinuity (MLD) that include (1) presence of partial melts or fluids, (2) layered anisotropy, (3) layered composition, and (4) elastically accommodated grain boundary sliding. However, all of these models have some limitations and cannot explain all the characteristics of the MLD. Here we propose a new model for the genesis of the MLD and explore its mechanism through thermomechanical numerical modeling at subduction zones. In the model, the deforming lithospheric mantle is affected by grain size reduction and growth processes. Numerical results show that the lithospheric deformation induced by subduction causes the grain size to sharply decrease within the 10-20 km thick brittle/ductile transition zone over significant regions inside the lithosphere. The depth depends mainly on the age of oceanic lithosphere and the thickness of continental lithosphere and is consistent with the observations. In addition, based on the previous study of dislocation slip-system and related olivine fabrics in the mantle, grain size reduction plays an important role in fluid pumping and phase nucleation through grain boundaries. This may in turn produce an increased intra-lithospheric water content resulting in high electrical conductivities and large seismic velocity drops at the MLD depths.
Application of the Foreshock Traffic Light System to the 2019 Ridgecrest sequence
Authors: Gulia Laura , Wiemer Stefan , Vannucci Gianfranco
Published: March 2021

The relative earthquake size distribution, or b-value of the Gutenberg and Richter relationship, can act as an indirect stress meter in the earth crust, a finding confirmed in numerous laboratory studies but also in diverse natural systems.  In 2018, we analysed the average size-distribution of about 60 well-monitored earthquakes sequences showing that, after a mainshock with M>=6, the b-value increases by about 20% respect to the background reference value.

In 2019, based on such result, we hypothesized and demonstrated that it may be possible, under specific circumstances, to discriminate if an ongoing sequence is representing a typically decaying aftershock sequence or rather foreshocks to an upcoming larger event.  We proposed a simple traffic light classification to assess in near real-time the level of concern for subsequent larger event, and tested it against 58 sequences, reaching a classification accuracy of 95%.

The Foreshock Traffic Light System (FTLS) has been implemented in a pseudo-prospective test to the 2019 Ridgecrest sequence. Results are fully in line with the hypothesis: in this Ridgecrest case study, after analyzing carefully the magnitude of completeness of the sequences, we find that in the hours after the first Mw6.4 Ridgecrest event, the b-value drops by 23% on average, when compared to the background value, resulting in a red foreshock traffic light. Spatially mapping the changes in b, we identify an area to the north of the rupture plane as the most likely location of a subsequent event. After the second, magnitude-7.1 mainshock, which did occur in the low b-value region, the b-value subsequently increased by 26% over the background value, triggering a green traffic light setting. Here we will report on these findings, discuss additional case studies, criticisms raised and discuss physics-based mechanics that may allow us to understand and model the observations.
Inter-model differences in tropical free-tropospheric humidity and their impact on the clear-sky radiation budget in global storm-resolving simulations
Authors: Lang Theresa , Naumann Ann Kristin , Stevens Bjorn , Buehler Stefan A.
Published: March 2021

Although the humidity distribution in the tropical free troposphere plays a key role in controlling the Earth’s energy budget, it is poorly simulated in Global Circulation Models (GCMs). A major uncertainty in these models arises from parameterizations of unresolved processes, above all the convective parameterization. An important step in global atmospheric modelling has been made with global storm-resolving models (GSRMs). By forgoing the convective parameterization GSRMs nourish the hope that they better represent processes relevant for humidity, but it is unclear to what extent the uncertainty in free-tropospheric humidity is reduced. The main goal of our study is to quantify this uncertainty as well as the resulting uncertainty in the clear-sky radiation budget based on the spread in an ensemble of GSRMs called DYAMOND. We find that the inter-model spread in relative humidity (RH) in DYAMOND has reduced by at least a factor of two throughout most of the free troposphere compared to the GCMs that participated in the CMIP5 AMIP experiment. However, the remaining RH differences in DYAMOND still cause a considerable inter-model spread of 1.2 Wm-2 in tropical mean clear-sky outgoing longwave radiation (OLR). For the most part this spread is caused by the RH differences in the lower and mid free troposphere, whereas RH differences in the upper troposphere (above 10 km) have a minor impact on OLR. We only find a direct connection between anomalies in RH and anomalies in the resolved humidity transport in the upper troposphere, suggesting that differences in the parameterizations of unresolved processes like microphysics and turbulence play a major role in the altitude regions with the strongest impact on OLR. Comparing model fields in moisture space, i.e. sorted from the driest to the moistest atmospheric column, reveals that two tropical regimes contribute most to the spread in tropical mean OLR: the driest subsidence regimes and moist regimes at the transition from deep convective to subsidence regions.
LPCMCI: Causal Discovery in Time Series with Latent Confounders
Authors: Gerhardus Andreas , Runge Jakob
Published: March 2021

The quest to understand cause and effect relationships is at the basis of the scientific enterprise. In cases where the classical approach of controlled experimentation is not feasible, methods from the modern framework of causal discovery provide an alternative way to learn about cause and effect from observational, i.e., non-experimental data. Recent years have seen an increasing interest in these methods from various scientific fields, for example in the climate and Earth system sciences (where large scale experimentation is often infeasible) as well as machine learning and artificial intelligence (where models based on an understanding of cause and effect promise to be more robust under changing conditions.)

In this contribution we present the novel LPCMCI algorithm for learning the cause and effect relationships in multivariate time series. The algorithm is specifically adapted to several challenges that are prevalent in time series considered in the climate and Earth system sciences, for example strong autocorrelations, combinations of time lagged and contemporaneous causal relationships, as well as nonlinearities. It moreover allows for the existence of latent confounders, i.e., it allows for unobserved common causes. While this complication is faced in most realistic scenarios, especially when investigating a system as complex as Earth's climate system, it is nevertheless assumed away in many existing algorithms. We demonstrate applications of LPCMCI to examples from a climate context and compare its performance to competing methods.

Related reference:
Gerhardus, Andreas and Runge, Jakob (2020). High-recall causal discovery for autocorrelated time series with latent confounders. In Advances in Neural Information Processing Systems 33 pre-proceedings (NeurIPS 2020). 
Beyond the technocratic truth to establish eco-development in the uplifted area of the Finnish southwestern shear coast as observed from space
Authors: Verstraeten Guido J. M. , Verstraeten Willem W.
Published: March 2021

Decisions about preventing further climate change involve human means for obtaining an equal and fair result for all humans. In consequence we have to make room for a complete different discours balancing between natural facts obeying natural laws and social behavior according to Duhem-Quine´s principle. In order to explain complex phenomena such as global warming and the isostatic uplift one should reject any one-hypothesis claim according to Duhem-Quine´s principle.

Considering climatologic problems as only pure positive scientific matter for making decisions for mankind how to deal with, is a pure essentialist and substantivistic conception of decision making. While climatologic models explain changes globally, the more unpredictable weather concerns rather local scales, implying that decisions must be adapted to the local situation. The unpredictability of some processes is universal but the consequences can be very local and form the boundary conditions of living. Stated otherwise, we do not just live on the planet Earth, but we live in a specific village/town in a specific region/country. 

Contrary to the widely accepted dominant paradigm decision making should not be based on the slogan ‘think global, act local’, but from the device ‘think local, manage the local effects of global warming’. Indeed, worldwide climate change will generally cause raising oceans, but more locally it will restore the former water balance of uplifted shear costs in Sweden and Finland and it affects the small fisher and farmer societies.

Here we suggest that knowledge of climate changes does not intervene in terms of their universal value such as truth, but under the local horizon of the social practices, artefacts and hierarchical relations with which they are associated. We advocate to reverse the former dominant technical code monopolized by technocracy from dominance of nature to creation of progress of the encroaching new ecosystems that develops out of the original shear coast in south-western Finland. We show based on Landsat imagery that this coast is rapidly changing due to the uplift. Furthermore, we demonstrate that the Eco-Development paradigm may rebalance nature, environment, humans and culture and that it is a valid alternative against the past and present-day socio-economical approach that have accelerated the change of the Earth’s climate, provided the global technocracy´s codes of the dominant paradigm are converted into local adapted social, economic and political codes.
Low-Budget Sewage Overflow Monitoring
Authors: Spill Caroline , Ditzel Lukas , Brumm Nora , Böhm Julia , Gassmann Matthias
Published: March 2021

Sewage overflows in headwater catchments are critical, mostly not well monitored point sources for many pollutants such as oxygen depleting substances, pharmaceuticals or heavy metals. The outlets are often located at places where no connection to the power grid is available, hence it is often necessary to provide deployed sensors or sampling devices with mobile power sources like car-batteries. In addition, autosamplers or on-line sensors are expensive devices. For these reasons, a proper monitoring strategy, including water quality parameters in these structures is often complicated to implement and from an economical point of view not reasonable. Therefore, we combined two low-budget DIY devices, a modified Zurich sequential sampler for time-discrete rainfall samples and Stream Temperature, Intermittency, and Conductivity loggers (STIC), to build a low-budget monitoring system being able to take time-discrete samples from sewage overflow. Our modified sampler collects 12 samples in a row, with variable volumes from 0.25 to 0.5 L. In each bottle a STIC was implemented. The STICs start to measure a conductivity higher than zero as soon as water starts to flow into the bottle. This allows for a clear assignment between sample and time. We called this sampler the Sewage Overflow Monitoring Sampler (SOMS).

Though the probe volume and the time period for sampling is strongly limited, concentration variations, including peak concentrations, in sewage overflows are expected to be measured right at the beginning of an event (first flush) and should be therefore covered by the sampler. First laboratory tests were successful. In the next step the monitoring system will be implemented on a field side.

Depending on the scientific question of the study, the SOMS can be complemented in the field by either another STIC logger or a pressure probe. The STIC logger is located at the bottom of the canal. This allows the detection of the duration of the overflow event. By installing a pressure probe the discharge can be approximated as long as gradient and the geometry of the canal is known.