bluuebunny/crossref_metadata_2025 huggingface dataset:
Revisiting the factors that drive interannual variability in stratospheric entry water vapour
Authors: Ziskin Ziv Shlomi , I. Garfinkel Chaim
Published: March 2020

Understanding the sinks, sources and transport processes of stratospheric trace gases can improve our prediction of mid to long term climate change. In this study we consider the processes that lead to variability in stratospheric water vapor. We perform a Multiple Linear Regression(MLR) on the SWOOSH combined anomaly filled water vapor product with ENSO, QBO, BDC, mid-tropospheric temperature, and CH4 as predictors, in an attempt to find the factors that most succinctly explain observed water vapor variability. We also consider the fraction of entry water vapor variability that can be accounted for by variations of the cold point temperature as an upper bound on how much water vapor variability is predictable from large scale processes. Several periods in which the MLR fails to account for interannual variability are treated as case studies in order to better understand variability in entry water not governed by these large scale processes.
Soil nutrients dynamics and the evolution of multi-decadal degradation in alpine wetlands of the Qinghai-Tibetan Plateau
Authors: Li Hailing , Li Tingting , Sun Wenjuan , Zhang Wen , Yu Lijun , Guo Bin , Liu Jia , Zha Xingchu
Published: March 2020

The Qinghai-Tibetan Plateau (QTP) is the highest plateau on earth and has a large area of alpine swampy meadows. In the past few decades, overgrazing and climate change have caused severe desiccation and degradation of the alpine wetlands. The remote sensing technology has been used to assess the wetland shrinkage. However, changes in soil nutrients associated with the duration of alpine wetland degradation are poorly known. We took soil samples in three swampy meadows of the QTP, one terrain was relatively flat and the other two were with hummocks and hollows. Decadal gradients of degradation from nondegraded swampy meadows to degraded meadows were selected. The contents of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) were analyzed. The SOC, TN, and TP contents loss in degraded swampy meadows occurred mainly during the first decade. The soil nutrients loss was highly affected by the geomorphic characteristics of the wetland area. After degradation, the SOC, TN, and TP contents decreased at exponential rates on the flat terrain site. The top layer SOC, TN, and TP contents of the degraded about 30 years area were 24.76±0.91, 2.22±0.07 and 0.45±0.01 (mean ± SE) g kg-1, respectively; and the SOC, TN, and TP contents decrease were 75%, 72% and 56% that of the nondegraded swampy meadows, respectively. On one hummock-hollow sites the top layer SOC, TN, and TP contents of the degraded for about 30 years area were 61.22±11.94, 4.09±0.73 and 0.44±0.05 (mean ± SE) g kg-1, respectively; and the SOC, TN, and TP contents decrease were 45%, 52% and 46% that of the nondegraded swampy meadows, respectively. The soil nutrients decomposition rate of hummock-hollow sites was much lower than the flat terrain site. Large and tough hummocks in swampy meadow degradation sites can resist environment erosion and stabilize soil nutrients content at high levels.
A new spectrum model for the atmospheric crosswind component applicable from mesoscales to microscales
Authors: Larsén Xiaoli , Larsen Søren , Petersen Erik , Mikkelsen Torben
Published: March 2020

A crosswind spectrum model Sv(f) is proposed that covers both the meso and the microscale, ranging in frequency 1/5 day-1 to the turbulence inertial subrange. The purpose is to improve the calculation of flow meandering effect over areas of the sizes of offshore wind farms and clusters.

The development is based on measurement (from Høvsøre) analysis over this broad frequency range for cases where wind direction does not change much during a day. The model reads:

fSv(f) = Boundary-layer model   for f>f1,

         = Constant                           for f2<f<f1,

         = a1f -2/3 + a2f -2                     for f<f2

Here, the frequency range f2 to f1 defines the gap region, and the constant in this subrange is determined by the spectra on both sides of this range; the boundary-layer model used here is either the Kaimal model or the Mikkelsen-Tchen model; a1 and a2 are climatological coefficients. The credibility of the model is evaluated against with measurements from another wind test site Østerild, with measurements ranging in height from surface layer to a height of 241 m.   

The model is used together with a similar model for the longitudinal wind component u to obtain time series u(t) and v(t), from which direction statistics are obtained and compared with those from measurements. It was found that the boundary-layer models could only describe stationary time series for wind vectors. The new v-spectral model improves significantly the statistics of wind direction variation over scales that correspond to offshore wind farms and clusters.
Intermittency of gravity waves modelled by a transient gravity-wave parametrization coupled with convective sources
Authors: Kim Young-Ha , Bölöni Gergely , Borchert Sebastian , Chun Hye-Yeong , Achatz Ulrich
Published: March 2020

The intermittency of gravity waves (GWs) is investigated using Multi-Scale Gravity Wave Model (MS-GWaM) implemented in the upper-atmosphere extension of ICON model. The intermittency of GWs is originated from that of wave sources but altered during propagation of the waves. Conventional GW parametrization (GWP), which diagnoses vertical profiles of GW properties under the steady-state assumption, can take into account the source intermittency if the GWP employs flow-dependent sources, while it cannot present the change of intermittency by transient evolutions of GWs. MS-GWaM is a prognostic model that explicitly solves the evolution of positions of waves (as well as their wavenumbers and amplitudes) in time and thus capable of describing the intermittency change. In order to include the source intermittency and variability, we couple the convective source, as diagnosed by subgrid-scale cumulus parametrization in ICON, to MS-GWaM, based on an analytic formulation of GW response to this source. In addition to this, a spatio-temporally uniform, persistent source is prescribed in the extratropics to take into account other non-orographic sources. Orographic sources are currently not used. The GW intermittency is measured by the Gini index, and is found to be quite high in the tropics, compared to that in the extratropics. In both regions, the index has similar values to those obtained from superpressure balloon observations reported in previous studies. A control experiment is performed using GWP based on the steady-state assumption, but coupled to the same wave sources, to assess the effects of transient modelling using MS-GWaM on the simulated intermittency. From comparison to the control experiment, the intermittency is found to increase largely for GWs from the uniform source but to decrease for convective GWs by the transient modelling.
Multiproxy climate and sea ice reconstruction of the industrial era at the Western Antarctic Peninsula
Authors: Vorrath Maria-Elena , Cárdenas Paola , Rebolledo Lorena , Shi Xiaoxu , Müller Juliane , Lange Carina B. , Mollenhauer Gesine , Muñoz Praxedes , Martínez Méndez Gema , Geibert Walter , Esper Oliver
Published: March 2020

Recent changes and variability in climate conditions leave a significant footprint on the distribution and properties of sea ice, as it is sensitive to environmental variations. We investigate the rapidly transforming region of the Western Antarctic Peninsula (WAP) focusing on the conditions and development of sea ice in the pre-satellite era. For this study on past sea ice cover we apply the novel proxy IPSO25 (Ice Proxy for the Southern Ocean with 25 carbon atoms; Belt et al., 2016). Three sampling sites were selected to cover areas near the Antarctic mainland, in the Bransfield Basin (2000 m depth) and the deeper shelf under an oceanographic frontal system. Analysis of short cores (multicores) resolving the last 200 years (based on 210Pbex dating) focused on geochemical bulk parameters, biomarkers (highly branched isoprenoids, GDGTs, sterols) and diatoms. These results are compared to multiple climate archives and modelled data. This multiproxy based approach provides insights on changes in spring sea ice cover, primary production regimes, subsurface ocean temperature (SOT based on TEXL86) and oceanographic as well as atmospheric circulation patterns. While environmental proxies preserved in two cores near the coast and in the Bransfield Basin reflect the properties of water masses from the Bellingshausen Sea and Weddell Sea, respectively, data from the third core at the deeper shelf depict mixed signals of both water masses. Our study reveals clear evidence for warm and cold periods matching with ice core records and other marine sediment data at the WAP. We observe a general decrease in SOT and an increase in sea ice cover overprinted by high decadal fluctuations. Trends in SOT seem to be decoupled from atmospheric temperatures in the 20th century, and this is supported by previous studies (e.g. Barbara et al., 2013), and may be related to the Southern Annual Mode. We consider numerical modelling of sea ice conditions, sea surface temperature and SOT for further support of our findings.

 

References:

Barbara, L., Crosta, X., Schmidt, S. and Massé, G.: Diatoms and biomarkers evidence for major changes in sea ice conditions prior the instrumental period in Antarctic Peninsula, Quat. Sci. Rev., 79, 99–110, doi:10.1016/j.quascirev.2013.07.021, 2013.

Belt, S. T., Smik, L., Brown, T. A., Kim, J. H., Rowland, S. J., Allen, C. S., Gal, J. K., Shin, K. H., Lee, J. I. and Taylor, K. W. R.: Source identification and distribution reveals the potential of the geochemical Antarctic sea ice proxy IPSO25, Nat. Commun., 7, 1–10, doi:10.1038/ncomms12655, 2016.
Seasonality in Lena River biogeochemistry and dissolved organic matter
Authors: Juhls Bennet , Overduin Pier Paul , Stedmon Colin Andrew , Morgenstern Anne , Meyer Hanno , Heim Birgit , Hölemann Jens , Povazhnyi Vasily
Published: March 2020

The carbon export by rivers to the Arctic Ocean is expected to increase in response to the rapidly changing climate in the Arctic (Camill, 2005; Freeman et al., 2001; Frey and Smith, 2005). This is in part due to thawing permafrost and mobilization of particulate and dissolved organic matter (DOM). The Lena River delivers approximately one fifth of the total river discharge to the Arctic Ocean and is the main source of DOM in the Laptev Sea shelf (Thibodeau et al., 2014). To date river fluxes of DOM have been based on sparse coverage of sample across the hydrograph about 700 km upstream (Cooper et al 2005; Raymond et al 2007; Stedmon et al 2011; Amon et al 2012). The effects of low frequency sampling on load estimates are unknown and potentially large for systems such as these where there are considerable changes across the hydrograph.   Here we present results from a unique high frequency sampling program and evaluate its viability to monitor export fluxes of DOM and its biogeochemistry in the Lena River. The sampling takes place close to the river mouth at the research station Samoylov in the central Lena River Delta. The Samoylov research station allows a unique chance for continuous sampling since it operates throughout the year. The sampling program includes measurements of several water parameters, such as temperature, electric conductivity, dissolved organic carbon (DOC), spectral CDOM absorption (aCDOM), fluorescent dissolved organic matter (FDOM) and water stable isotopes.
The data facilitated the identification of the main drivers behind the seasonality of DOM concentration and biogeochemistry of the Lena River. Three main water sources could be identified (1) (snow) melt water, (2) rain water and (3) subsurface water. Melt and rain water are found to be the prevailing water sources that combined transport 5.8 Tg C dissolved organic matter (~ 85 % of annual flux (6.8 Tg C)) into the Lena River. The high number of samples throughout the whole year allowed flux calculations that are independently from load models that likely lead to a large variation of earlier studies.
The absorption properties of DOM revealed changing composition and sources of DOM throughout the year. Decreasing SUVA values during the summer point towards an increasing fraction of old DOM which potentially originates from degrading permafrost. In contrast, during the spring freshet, high SUVA indicate mostly fresh organic matter with high molecular weight and high aromaticity.
This dataset represents the first year of a planned long-term monitoring program at the Research Station Samoylov Island and provides a baseline data set against which future change of this large integrative system may be measured. A continuous sampling of Arctic River water will facilitate to identify intra and inter-annual trends with ongoing climate change.
Rapid collaborative knowledge building via Twitter after significant geohazard events
Authors: Lacassin Robin , Devès Maud , Hicks Stephen P. , Ampuero Jean-Paul , Bossu Rémy , Bruhat Lucile , Daryono Daryono , Wibisono Desianto F. , Fallou Laure , Fielding Eric J. , Gabriel Alice-Agnes , Gurney Jamie , Krippner Janine , Lomax Anthony , Sudibyo Muh. Ma'rufin , Pamumpuni Astyka , Patton Jason R , Robinson Helen , Tingay Mark , Valkaniotis Sotiris
Published: March 2020

Twitter is an established social media platform valued by scholars as an open way to disseminate scientific information and to publicly discuss research results. Scientific discussions on Twitter are widely viewed by the media who can then pass on information to the public. Here, we take the example of two 2018 earthquake-related events which were widely commented on Twitter by geoscientists: the Palu Mw7.5 earthquake and tsunami in the Indonesian island of Sulawesi and the long-duration (more than one year) seismo-volcanic crisis Mayotte island in the Comoros archipelago between Africa and Madagascar. We build our analysis on a content and contextual analysis of selected Twitter threads about the geophysical characteristics of these events. Most authors of this paper have participated to these Twitter threads and related discussions, and regularly explain geohazard events via this social media. From the two selected examples, we show that Twitter promotes very rapid building of knowledge – in the minutes to hours and days following an event – via an efficient exchange of information and active discussion between the scientists themselves and with the public. Combining these results with our own experience of communicating geohazard science via Twitter, we discuss the advantages and potential pitfalls of this relatively novel way to make scientific information accessible to scholarly peers and to lay people. We argue that scientific discussion on Twitter breaks down the traditional “ivory towers” of academia. It participates to the growing trends towards open science, making science accessible to any non-academics or citizen scientists who can follow and participate in the discussion. This may help people to understand how science is developed, and, in the case of natural/environmental hazards, to better understand their risks.
A first attempt to model an Artificial Ice Reservoir (Ice Stupa) using a simple energy balance approach
Authors: Balasubramanian Suryanarayanan , Hoelzle Martin , Lehning Michael , Wangchuk Sonam , Oerlemans Johannes , Keller Felix
Published: March 2020

Artificial Ice Reservoirs (AIRs, also called icestupas) have been successful in storing water during winter and releasing the water during spring and summer. Therefore, they can be seen as a vital fresh water resource for irrigation in dry environments. Many different forms of AIRs do exist and not many studies have tried to model theses ice structures.
We will present simulations of the most important physical processes that causes the formation and melt of AIRs using one dimensional equations governing the heat transfer, vapour diffusion and water transport of a phase changing water mass. For validation, an AIR was constructed in Schwarzsee region in the Canton of Fribourg, Switzerland. Meteorological data in conjunction with fountain discharge data was measured. According to the model, the Schwarzsee AIR was able to store and discharge 850 litres or  3.7 percent of all the water sprayed over a duration of 41 days. Alternate model scenarios will also be presented to show how this freezing efficiency can be increased.
Lutetian conid snails from the Paris and Hampshire Basins as seasonality archives of the middle Eocene
Authors: Clark Alexander , Vellekoop Johan , Keleman Zita , Speijer Robert
Published: March 2020

During the Lutetian (middle Eocene, 48-41 Ma), Earth’s climate was in transition from greenhouse to icehouse conditions, sometimes referred to as a “doubthouse climate”. These circumstances allowed the Paris Basin (France) and Hampshire Basin (UK) to be hotspots for marine biodiversity, hosting a diverse assemblage of molluscs, including members of the Conidae family. Most species within the family are known to live for multiple years, possibly up to a decade, in fully marine conditions and mostly in shallow waters. Under these fully marine conditions, Conidae shells would be excellent recorders of sea water temperatures, allowing paleotemperature reconstruction for the two basins. However, climatic parameters such as temperature extremes or seasonality have not been well documented in the two basins during the Lutetian, with only a handful of studies available [Andreasson & Schmitz 2000, Huyghe et al. 2015]. Here, we made longitudinal and latitudinal comparisons between the two basins, using carbon and oxygen stable isotope data measured on different Conidae species, in order to provide seasonality reconstructions in north-western Europe. The focus of this research is mainly on assessing isotopic variation of seasonality within a basin and comparison between basins, including previously published data. SEM and cold cathodoluminescence shows that for both basins the preservation of the mollusc carbonate is sufficient to allow for approximations of the original environmental conditions. Three specimens from each basin were sampled by means of manual drilling along the growth axis of the shells. Obtained stable carbon and oxygen isotope data were used to reconstruct variation in paleotemperature and productivity. Following the methodology of Kobashi & Grossman 2003, patterns in the isotopic signature throughout the life of each specimen give an indication of the environmental reconstruction and any internal variability. By comparing existing and newly collected data from the same localities and family, we examine whether differences in seasonality are species-specific, due to climatic variation, or reflect environmental differences. 
Andreasson, F.P., Schmitz, B. (2000) Temperature seasonality in the early middle Eocene North Atlantic region: Evidence from stable isotope profiles of marine gastropod shells, GSA Bulletin, 112, 628-640. 
Huyghe, D., Lartaud., F., Emmanuel, L., Merle, D., Renard, M. (2015) Palaeogene climate evolution in the Paris Basin from oxygen stable isotope (δ18O) compositions of marine molluscs. Journal of the Geological Society, 172, 576-587. 
Kobashi, T., Grossman, E.L. (2003) The oxygen isotopic record of seasonality in Conus shells and its application to understanding late middle Eocene (38 Ma) climate, Paleontological Research, 7, 343-355. 
Retrieving the Ocean Interior Structure from Surface Data:FOAGRNN and SQG-mEOF-R
Authors: Wang Huizan , Zhang Ren , Bao Senliang , Yan Henqian , Zhang Weimin , Zhang Xiaojiang
Published: March 2020

As many oceanic observations can only reflect the sea surface, such as satellite data, the retrieval of the ocean interior structure from sea surface information is of great importance for us to understand the three-dimensional ocean. In order to retrieve the three-dimensional salinity and density structure from surface data, two new method are proposed as follows. One proposed method is called generalized regression neural network with the fruit fly optimization algorithm (FOAGRNN), which is a nonlinear method and used to estimate subsurface salinity profiles from sea surface parameters. Compared with linear methodology, the estimated salinity profiles from the FOAGRNN method are in better agreement with the measured profiles at the halocline.The results suggest a potential new approach for salinity profile estimation derived from sea surface data. The other proposed method is called SQG-mEOF-R, which estimate the interior density from the sea surface density (SSD) and sea surface height (SSH) by combining the dynamical surface trapped mode derived from the Surface Quasi-Geostrophic (SQG) function with the statistical mode calculated from multivariate EOF reconstruction (mEOF-R) method and. This method is applied to the eddy-resolving OFES (Ocean General Circulation Model For the Earth simulator) simulation and compared with the conventional SQG or isQG (interior plus SQG) and mEOF-R methods. The results manifest that, no matter in the NorthWest Pacific (NWP) region dominated by surface-intensified eddies or the SouthEast Pacific (SEP) region characterized by subsurface-intensified eddies, SQG-mEOF-R perform a robust work in mesoscale density reconstruction.
Solar Influences on Stratospheric Circulation Patterns
Authors: Givon Yonatan , Garfinkel Chaim
Published: March 2020

The impact of the solar cycle on the NH winter stratospheric circulation is analyzed using
simulations of a Model of an idealized Moist Atmosphere (MiMA). By comparing solar minimum
periods to solar maximum periods, the solar impact on the stratosphere is evaluated: Solar
maximum periods are accompanied by warming of the tropics that extends into the midlatitudes
due to an altered Brewer Dobson Circulation. This warming of the subtropics and the altered
Brewer Dobson Circulation leads to an increase in zonal wind in midlatitudes, which is then
followed by a decrease in E-P flux convergence near the winter pole which extends the enhanced
westerlies to subpolar latitudes.
We use the transformed Eulerian mean framework to reveal the processes that lead to the
formation of this sub-polar zonal wind anomaly and its downward propagation from the top of the
stratosphere to the tropopause.
Monitoring of the mass and heat transfers through a heterogeneous karstic limestone vadose zone of an agricultural field (Beauce Aquifer, Orleans, France)
Authors: Abbar Bouamama , Jodry Clara , Isch Arnaud , Laurent Gautier , Azaroual Mohamed
Published: March 2020

The extent and the fluid dynamics of the vadose zone (VZ) of an aquifer have a direct impact on the aquifer recharge, the water quality and the pollutants transfer from the soil to the groundwater. The water – rock interactions and mass and heat transfers under the impact of microbial processes and agricultural practices could undergoes significant changes in the chemical composition of the water flowing throughout the VZ, which may induce pollution of groundwater.

The growing dependence on groundwater for potable water supplies draws attention to protect the quality of groundwater resources at national and international levels to the need. It is important to detect the contamination risk of aquifers and develop an integrated water management methodology based on innovative environmental monitoring tools and sophisticated numerical models to protect groundwater resources and guarantee their good quality for domestic, agricultural and industrial needs. For this reason, the monitoring of VZ dynamics has become essential to study the transfer mechanisms of mass (water, gas and contaminants) and heat from the soil to the groundwater. This should allow rapid detection of the pollutants migration through an aquifer and take relevant measures to protect groundwater before the contaminants reach the water table.

In this context, an Observatory of transfers in the vadose zone (O-ZNS) is being developed at Villamblain (Orléans, France) in an agricultural field. The O-ZNS project consists of a well with a diameter of 4 m and a depth of 20 m which will allow access to the entire VZ of the Beauce aquifer. The main target of the O-ZNS platform is to acquire original and unique data on the reactive transfers of fluids and heat in the VZ, in order to follow in situ and in real time the highly coupled physical, chemical, and biological processes taking place over the long term. The O-ZNS project also aims to assess the performance of all types of instrumentation dedicated to non-destructive measurement or local sampling of fluids, rocks, and microbs in the VZ for long duration.

To meet these objectives, a myriad of innovative monitoring tools (e.g.,environmental sensors, fiber optic sensors, geophysical imaging, ….) will be deployed in the O-ZNS from the soil surface to the aquifer (from 0 to 20 m deep) using the well and the surrounding boreholes. Also, note that to date, there are still difficulties in the instrumentation of rock materials and relevant solutions must be developed. These environmental monitoring techniques will allow to generate a huge quantity of data on the physical, chemical, and microbiological coupled processes.
Localized enhancements of total electron content in Southern Hemisphere
Authors: Edemskiy Ilya , Edemskiy Ilya
Published: March 2020

Localized enhancements of total electron content (TEC) are usually registered during magnetic storms and are often believed to be connected with storm enhanced density (SED) events. Investigating global ionospheric maps we found that such localized TEC enhancements (LTE) could be observed in Southern Hemisphere during both disturbed and quiet time with no clear dependence on parameters of near space. Analysis of occurrence of LTEs in the regions of Indian and Southern Atlantic Oceans showed that part of them (observed during magnetic storms and localized in subpolar latitudes) can be connected with SEDs. Since another part of subpolar LTEs is detected during relatively quiet conditions its generation mechanism should be different despite they have similar spatial distribution. Most of the enhancements are observed in middle latitudes and is detected during all the investigated years. The occurrence rate of LTEs hardly depends on solar activity and the most probable season for LTE detection is April-September (autumn-winter).

Here we investigate reasons of generation both midlatitudinal and subpolar LTEs trying to define the mechanisms of their generation in details.
Oligocene-Miocene benthos biogeography of the Indian Ocean
Authors: Harzhauser Mathias , Reuter Markus , Piller Werner E.
Published: March 2020

With the final closure of the Tethys Seaway during the early Miocene the Indian Ocean came into existence as geographic entity. The total breakdown of faunistic interrelations between the proto-Mediterranean Sea and Indian Ocean during the Aquitanian suggests a major biogeographic separation around ~22 Ma somewhere between Mesopotamia, Arabia, and NW-India. This event predates the development of the so-called Gomphotherium landbridge in the Burdigalian by 4-5 Ma and provides an example for biogeographic separation in the marine realm without formation of a continental barrier. The benthic mollusk fauna of the Miocene Indian Ocean was far from uniform. Data on Oligocene and Miocene mollusks from southern Iran (Qom Basin, Makran), the Sultanate of Oman, Tanzania, northern India (Kutch), southern India (Kerala) and Sri Lanka document a complex pattern of faunistic relations between these areas with high rates of endemism. Thus, a strong early Miocene bioprovincialism can be postulated for the Proto-Indo-West Pacific Region with a Central East African Province, a East African-Arabian Province, a Western Indian Province and a Proto-Indo-Polynesian Province in the east. This pattern differs fundamentally from the modern biogeography in the Indian Ocean. Similarly, fossil reef coral faunas from Eastern Africa (Tanzania, Somalia) show a low relation with southern Iran and no relationship with Indonesia during the Oligocene and early Miocene, but a strong faunistic affinity with Indonesia during the late Miocene and Recent.

We postulate that three main factors explain the strong difference between the Oligocene-Miocene and modern biogeographic patterns: the absence of the Miocene Indian Ocean Equatorial Jet, which did not arise before the middle Miocene, the absence of the Indonesian Throughflow due to the completely different paleogeography, and finally the devasting effect of Pleistocene sea-level fluctuations and subsequent recolonizations of the Indian Ocean from the east.

 

This project was funded by the Austrian Science Fund (FWF, Grants P 18189-N10 and P 29158-

N29).
Influence of disdrometer type on rainfall kinetic energy measurement
Authors: Lolk Johannsen Lisbeth , Zambon Nives , Strauss Peter , Dostal Tomas , Neumann Martin , Zumr David , A. Cochrane Thomas , Klik Andreas
Published: March 2020

Rainfall kinetic energy (KE) is an important indicator for the potential soil loss due to rainfall in erosion risk assessment. Kinetic energy-intensity (I) relationships have been developed as a means to calculate the KE of rainfall, when only the rainfall intensity is known. The direct measurement of KE has been enabled due to the use of disdrometers, which measure the size and velocity of raindrops. Previous measurements have shown that rainfall measurements for the same site differed among disdrometer types. Therefore, the best fitting KE-I relationship is likely dependent on the type of disdrometer. In this study, the influence of the disdrometer-specific drop size and velocity measurements on the formulation of new KE-I relationships as well as the fit of existing equations from literature was investigated. Disdrometer rainfall data was collected in 1-minute intervals from six laser-based disdrometers. Two disdrometers of each of the following three types were compared: the PWS100 Present Weather Sensor from Campbell Scientific, the Laser Precipitation Monitor from Thies Clima and the first generation Parsivel from OTT Hydromet. The disdrometers were set up individually at sites in Austria, Czech Republic and New Zealand. Rainfall was measured between 2014 and 2019 with varying amounts of collected data for each site. The results revealed the inherent differences in drop size and velocity distribution estimation between different types of devices. The same pattern of rainfall drop size and velocity distribution could be seen for disdrometers of the same type despite spatial separation. This indicates that actual spatial differences in rainfall characteristics may be difficult to discern when comparing data from different types of disdrometers. New exponential KE-I relationships based on disdrometer data were formulated for each site and device. To confirm the use of the new KE-I equations, one of the equations was validated using rain gauge data from the same site. The best fit of literature KE-I equation varied among sites and devices. The relationship employed in the Revised Universal Soil Loss Equation (RUSLE) always underestimated KE with a percent bias ranging from -2 to -30 %. This study highlights the differences in disdrometer rainfall kinetic energy measurements and how these influence the formulation and evaluation of KE-I relationships, which are important in rainfall erosivity studies.
Mapping Groundwater Vulnerability and Risk of hydro-carbon Contamination in a Semi-Arid Region
Authors: Babika Zaharatu , Kjeldsen Thomas , bryant Lee
Published: March 2020

Groundwater is a scarce yet vital resource in many arid and semi-arid regions of the world. where it serves as water supply for a majority of the population. The quality of this resource is depreciating, however due to pollution levels reaching intolerable limits as a result of unplanned urbanization and industrialization. In this study, the capabilities of two commonly used groundwater vulnerability models, DRASTIC and GOD, are assessed for correctly classifying the risk of hydrocarbon pollution within the city of Kano, located in semi-arid northern Nigeria. Most existing groundwater vulnerability assessment tools have been developed for use in Europe and North America under generally humid conditions; conversely, vulnerability assessment of groundwater in arid and semi-arid is much less developed.
 Combined analysis of large-scale existing data sources on hydro-meteorological, environmental and anthropogenic factors will be used to evaluate the vulnerability of groundwater resources in Kano, a city of ~4 million people within 137 square kilometres.  In this study, the two models (DRASTIC and GOD) are assessed based on data provided by Nigerian water resources administrations and obtained via field monitoring to detect areas that are vulnerable to groundwater contamination based on the hydrogeological structure and local sources of hydrocarbon contamination. Several groundwater contamination sources have been identified such as automobile shops, household dumpsites, and petrol dispensing stations.Mapping of environmental factors was conducted within the framework of Geographical information systems (GIS), and  preliminary results show a range of very high to moderate vulnerability classes exist within the build-up areas of Kano. A sensitivity evaluation of the various parameters required for each of these models has also been performed to identify the controlling parameters within this semi-arid environment. Building on these results, the next phase of this research will focus on development of a modified vulnerability model based on these identified controlling parameters and model validation using field observations.
Studying the effects of droughts and heavy rain events on DOC in Scot pine in Belgium
Authors: Ariza Carricondo Cristina
Published: March 2020

Studying the effects of droughts and heavy rain events on DOC in Scot pine in Belgium

Cristina Ariza-Carricondo(1,2), Marilyn Roland(1), Bert Gielen(1), Eric Struyf(1), Caroline Vincke(2) and Ivan Janssens(1).

(1) PLECO, University of Antwerp, Belgium. (2) Faculty of Bioscience Engineering & Earth and Life Institute, University of Louvain-la-Neuve, Louvain-la-Neuve, Belgium.

Climate extremes, including extreme rain events, are becoming more frequent and more extreme, and affect the carbon cycle of ecosystems. Very little is known about how Dissolved Organic Carbon (DOC) production and leaching are affected by such precipitation extremes while the relation between dissolved and gaseous exports of carbon under different precipitation regimes remains unexplored.

Hydrological conditions are the main driver of DOC leaching and alterations in precipitation patterns may cause large changes in the carbon balance of forests. To test the effects of precipitation extremes on DOC, we designed a manipulation experiment in a Scots pine forest in Belgium.

One of the challenges to estimate DOC export is the quantification of water drainage flow. In this study we used self-designed Zero Tension Lysimeters (ZTL) to capture leaching water and analyze its DOC-concentrations as well as other elements along profiles in the soil (up to 75cm depth), to study how DOC moves under different precipitation regimes. Different manipulation experiments were performed where we modified the precipitation regime simulating heavy rain events after different droughts as well as experiments where we modified the precipitation intensity over time. Leached water was collected at different depths at monthly intervals after natural rain events as well as after irrigations.

Preliminary results showed that drainage water transported DOC differently through the soil when different amounts of water were added. Furthermore, more frequent small rain events appear to favor the production of DOC as compared to less frequent high intensity rain events, while DOC production ceases during droughts.
Comparison of the crust and upper mantle structure of the Alboran and Algerian domains (Western Mediterranean): Tectonic significance
Authors: Kumar Ajay , Fernàndez Manel , Vergés Jaume , Torne Montserrat , Jimenez-Munt Ivone
Published: March 2020

We present a comparison of the present-day crust to upper-mantle structure in the Western Mediterranean along two NW-SE oriented geo-transects in the Alboran and Algerian basins. The Alboran domain geo-transect traverses the Iberian Massif, the Betics, the Alboran Basin and ends in the northern margin of Africa between the Tell and Rif mountains. The Algerian domain geo-transect traverses the Catalan Coast Ranges, the Valencia Trough, the Balearic Promontory, the Algerian basin, the Greater Kabylies and ends in the Tell-Atlas Mountains in the northern margin of Africa. We model the thermal, density (i.e. compositional) and seismic velocity structure by integrating geophysical and geochemical dataset in a self-consistent thermodynamic framework. The crustal structure is constrained by seismic experiments and geological cross-sections, whereas seismic tomography models and mantle xenoliths constrain the upper mantle structure and composition. The Algerian Basin lithosphere shows a typical oceanic lithosphere composition, whereas the Alboran Basin lithosphere is slightly fertile. The lithospheric mantle beneath the Betics and Greater Kabylies are also fertile compared to the Iberian and African lithospheres showing the involvement of the fertile sublithosphere mantle during the later stages of subduction. In the Valencia Trough, the lithosphere is fertile in comparison to the Balearic Promontory lithosphere, which is similar to Iberian lithosphere. A lithosphere-scale thickening is observed in the Betics, and the Greater Kabylies, and thinning follows towards the Alboran and Algerian back-arc basins. Detached slabs with anomalous temperature of-320 oC, with oceanic lithosphere composition beneath the Greater Kabylies, and Iberian lithosphere composition beneath the Betics, are required to fit the geoid height. Our results impose important constraints for the geodynamic evolution models of the Western Mediterranean.

This work has been supported by SUBTETIS (PIE-201830E039) project, EU Marie Curie Initial Training Network ‘SUBITOP’ (674899-SUBITOP-H2020-MSCA-ITN-2015), the Agencia Estatal de Investigación through projects MITE (CGL2014-59516) and GeoCAM (PGC2018-095154-B-100), and the Agency for Management of University and Research Grants of Catalonia (AGAUR-2017-SGR-847).
TOMOREF operator for assimilation of GNSS tomography wet refractivity fields in WRF DA system
Authors: Hanna Natalia , Trzcina Estera , Kryza Maciej , Rohm Witold
Published: March 2020

The amount of water vapor in the atmosphere is highly variable and not easy to measure. One of the methods to provide reliable information about the amount and distribution of the humidity in the troposphere is GNSS (Global Navigation Satellite Systems) tomography. The GNSS tomography uses the observations of signal delays between satellites and ground-based receivers over the field covered by a GNSS network. This method enables deriving the 3D distribution of wet refractivity at a low cost in all weather conditions, with high temporal and spatial resolution.

The first applications of the GNSS tomography data in the Weather Research and Forecasting Data Assimilation (WRF DA) system were performed by the adaptation of the GPSREF observation operator. In this study, we present a new tool, namely the TOMOREF observation operator, which consists of three parts: forward, tangent linear, and adjoint operators. As the input data in the assimilation process, the wet refractivity fields from two tomographic models (TUW, WUELS) are used. The analysis is carried out for a 2-week long period (May 29 – June 14, 2013) in Central Europe when severe weather conditions occurred, including heavy precipitation events. The data assimilation results are verified against radiosonde observations, synoptic data, and ERA5 reanalysis. Moreover, the performance of the TOMOREF and GPSREF operators is examined. For the forecasts of relative humidity (RH) at a pressure level of 300 hPa, the implementation of the TOMOREF operator vanishes the negative impact caused by the GPSREF operator. Additionally, the improvement of the root mean square error of the forecasts of RH up to 0.5% is observed. Comparing to the assimilation of Zenith Total Delay observations, the application of the tomographic data has overall a greater influence on the WRF model. Consequently, the GNSS tomography data can be valuable in operational weather forecasting.
A model setup for simulations of ground-based scattered sunlight measurements
Authors: Wellmann Constanze , Proß Christin , Bigge Katja , Butz André
Published: March 2020

Remote sensing is an important measurement technique when probing the atmosphere as it is rather flexible and
allows for the measurement of numerous variables. For example, spectrometers are commonly used to quantify the
concentrations of trace gases by recording spectra of direct or scattered sunlight. Due to scattering, the light
paths between sun and detector can be rather complicated and radiative transfer models are necessary to retrieve
the information contained in the spectra.
Since these spectrometer measurements have to be made in spectral regions with strong absorption, it is necessary
to model many wavelengths to reach a sufficiently accurate representation of the absorption lines and their effects
on the light paths.
Thus, 1D models are often implemented for a fast analysis of the recorded spectra. However, this approach assumes
horizontal homogeneity and local sources cannot be resolved. In contrast, 3D Monte Carlo models are more realistic
and are able to represent this inhomogeneity, but they are computationally expensive and are not suitable for
operational use.
We improve an existing Monte Carlo model by implementing efficient algorithms for the simultaneous calculation of
several wavelengths to decrease the required computation time.
Furthermore, we examine to which scatter order the 3D model provides more detailed results while maintaining a
reasonable run time.
This finally leads to a coupling of these two types of radiative transfer models via the scatter order into one
efficient model which performs realistic simulations at a computational cost comparable to 1D models.
So we are able to detect sources along the line of sight of ground-based measurements of scattered sunlight.
Here, we present our objective and first results.
Strongly coherent dynamics of stochastic waves causes abnormal sea states
Authors: Slunyaev Alexey
Published: March 2020

The dynamic kurtosis (i.e., produced by the free wave component) is shown to contribute essentially to the abnormally large values of the full kurtosis of the surface displacement, according to the direct numerical simulations of realistic directional sea waves within the HOSM framework. In this situation the free wave stochastic dynamics is strongly non-Gaussian, and the kinetic approach is inapplicable. Traces of coherent wave patterns are found in the Fourier transform of the directional irregular sea waves. They strongly violate the classic dispersion relation and hence lead to a greater spread of the actual wave frequencies for given wavenumbers.

The research by is supported by the RSF grant No. 16-17-00041.

Slunyaev, A. Kokorina, The method of spectral decomposition into free and bound wave components. Numerical simulations of the 3D sea wave states. Geophysical Research Abstracts, V. 21, EGU2019-546 (2019).

A.V. Slunyaev, A.V. Kokorina, Spectral decomposition of simulated sea waves into free and bound wave components. Proc. VII Int. Conf. “Frontiers of Nonlinear Physics”, 189-190 (2019).

Slunyaev, A. Kokorina, I. Didenkulova, Statistics of free and bound components of deep-water waves. Proc. 14th Int. MEDCOAST Congress on Coastal and Marine Sciences, Engineering, Management and Conservation (Ed. E. Ozhan), Vol. 2, 775-786 (2019).

Slunyaev, Strongly coherent dynamics of stochastic waves causes abnormal sea states. arXiv: 1911.11532 (2019).
From a magma ocean to a solid mantle: implications for the thermo-chemical evolution of Mars
Authors: Bolrão Daniela , Ballmer Maxim , Morison Adrien , Rozel Antoine , Labrosse Stéphane , Tackley Paul
Published: March 2020

Several studies suggest that Mars went through an episode of Magma Ocean (MO) early in its history. When the MO crystallises, solid mantle appears. The crystallisation of this MO starts at the Core-Mantle Boundary (CMB) and continues upwards to the surface of the planet. Assuming that this process occurs by fractional crystallisation, the solid cumulates that form are progressively enriched in incompatible elements, including iron, and an unstable density stratification is developed. This stratification is thought to have resulted in a planetary-scale mantle overturn after MO crystallisation, potentially explaining the early magnetic field, crustal dichotomy and chemical heterogeneities present on martian mantle.

However, previous studies on the thermo-chemical evolution of Mars consider only fractional crystallisation of the MO, and lack the possibility of re-melting/re-freezing of material at the mantle-MO interface, before the MO is fully crystallised.

In this study we investigate the effect of re-melting/re-freezing of material at the mantle-MO interface during MO crystallisation, on the dynamics and composition of the solid mantle. We use a numerical method with the convection code StagYY. The solid mantle is represented by a 2D spherical annulus geometry, and the MO by a 0D object at top of the mantle. The boundary condition applied to the solid domain allows the parameterisation of fractional crystallisation/re-melting of material at the mantle-MO interface. We model the growth of the solid mantle from the CMB up to the surface of the planet, and we account for core cooling and the presence of an atmosphere.

We show that by taking re-melting/re-freezing of material into account, the onset of convection can start earlier in Mars history. These results bring implications for the density stratification and overturn, and to the existence of isotopically distinct reservoirs on the mantle. Moreover, our results show that the mode of convection is preferentially degree-1, which can potentially explain the crustal dichotomy. 
On the infrasound array monitoring in Romania: reprocessing of the data recorded by the national infrasound network
Authors: Ghica Daniela , Popa Mihaela , Ionescu Constantin
Published: March 2020

We present the results of the reprocessing a 10-year archive of waveform data recorded with the Romanian infrasound network, by using PMCC signal detector. Starting with 2009, three infrasound stations have been deployed on the Romanian territory by the National Institute for Earth Physics (NIEP): IPLOR 6-element array of 2.5 km aperture, in the central part of the country, BURARI 4-element research array of 1.2 km aperture, in the northern Romania, under the cooperation with Air Force Technical Application Center AFTAC (USA), and I67RO – a temporary PTS portable 4-element array of 0.9 km aperture, in western Romania, for two-year experiment (2016-2018), within a collaboration project with PTS/CTBTO. In 2019, BURARI station has been upgraded to 6-element array with a 0.7 km aperture.

Infrasound data are processed and analyzed on routinely basis at NIEP by using a duo of infrasound detection-oriented software – DTK-GPMCC and DTK-DIVA – packaged into CTBTO NDC-in-a-Box. Since October 2019, a new implementation of PMCC algorithm is available at NIEP, enabling the characterization of the coherent infrasound field in log-spaced frequency with one-third octave bands from 0.1 to 7 Hz. The full data set recorded with the Romanian infrasound stations has been reprocessed by applying the new PMCC algorithm.

The array monitoring performance resulted after the data reprocessing is investigated. Detection capability assessment, types of sources observed, as well the capacity of fusing the detections into support of understanding various infragenic sources are presented. A better characterization of the detected signals in the frequency-azimuth space or frequency trace-velocity space is clearly observed. Infrasonic signals generated by several relevant sources detected with the three arrays deployed on the Romanian territory are shown.