bluuebunny/crossref_metadata_2025 huggingface dataset:
How sensitive are rainfall interception models to the canopy parameters of semi-arid forests?
Authors: Eliades Marinos , Bruggeman Adriana , Djuma Hakan , Lubczynski Maciek W.
Published: March 2020

Quantifying rainfall interception can be a difficult task because the canopy storage has high spatial and temporal variability. The aim of this study is to examine the sensitivity of three commonly used rainfall interception models (Rutter, Gash and Liu) to the canopy storage capacity (S) and to the free throughfall coefficient (p).  The research was carried out in a semi-arid Pinus brutia forest, located in Cyprus. One meteorological station and 15 manual throughfall gauges were used to measure throughfall and to compute rainfall interception for the period between January 2008 and July 2016. Additionally, one automatic and 28 manual throughfall gauges were installed in July 2016. We ran the models for different sets of canopy parameter values and evaluated their performances with the Nash-Sutcliffe Efficiency (NSE) and the bias, for the calibration period (July 2016 - December 2019). We validated the models for the period between January 2008 and July 2016. During the calibration period, the models were tested with different temporal resolutions (hourly and daily). Total rainfall and rainfall interception during the calibration period were 1272 and 264 mm, respectively. The simplified Rutter model with the hourly interval showed a decrease of the NSE with an increase of the free throughfall coefficient. The bias of the model was near zero for a canopy storage between 2 and 2.5 mm and a free throughfall coefficient between 0.4 and 0.7. The Rutter model was less sensitive to changes in the canopy parameters than the other two models. The bias of the daily Gash and Liu models was more sensitive to the free throughfall coefficients than to the canopy storage capacity. The bias of these models was near zero for free throughfall coefficients over 0.7. The daily Gash and Liu models show high NSE values (0.93 – 0.96) for a range of different canopy parameter values (S: 0.5 – 4.0, p: 0 – 0.9). Zero bias was achieved for a canopy storage capacity of 2 mm and above and a free throughfall coefficient between 0 and 0.7. Total rainfall and rainfall interception during the validation period were 3488 and 1039 mm, respectively. The Gash model performed better than the Liu model when the optimal parameter set (highest NSE, zero bias) was used. The interception computed with the Gash model was 987 mm, while 829 mm with the Liu model. This study showed that there is a range of canopy parameter values that can be used to achieve high model performance of rainfall interception models.
The contribution of Web of Interactions framework to the whole system approach
Authors: Dor Haim Shayli , Orenstein Daniel , Shachak Moshe
Published: March 2020

The concept of whole system approach offers a foundation for ecosystem studies. Identification of the components and interaction demonstrate the challenges in the field of ecology, due to the lack of a conceptual and applied framework. we attend to present a theoretical foundation and a methodology for identifying components and interactions of the whole system approach linking biodiversity and geodiversity processes into ecosystem diversity as a web of interactions (WoI).

The web of interactions model combines the geodiversity components that include climate, geology, geomorphology, and hydrology processes and their interactions and the biodiversity components that include population, community, ecosystem, and landscape levels of organization and their interactions. Linking biodiversity and geodiversity produces ecosystem diversity, which is represented as a web of diversity interactions that include climate, rock, soil, species, genetic, and functional diversities

In the talk we will present examples from our long term study in the Negev Highland, an arid water limited environment. The system is characterized by high geodiversity (topographic, geologic, geomorphic, and pedologic diversity) and high biodiversity with many unique and endemic species.

Our study presents the whole system approach of the Negev Highlands ecosystem as a web of interactions (WoI) among and between the diversity of components that links biotic and abiotic diversities. All the components and their interactions vary in time and space and together determine ecosystem diversity.

Long term study in the Negev Highland site revealed various of diversities of the ecosystem that can be linked by hydro-geo-ecological components, drivers, and feedbacks that control geodiversity and biodiversity. The main feedbacks are: the hydrological feedback that controlled by rainfall pattern and affects the pedological feedback by runoff generation that accumulates dust and regulates rock-to-soil ratio. These two feedbacks control soil moisture, which links geodiversity with biodiversity components. In addition, an energy and material feedback which is characterized by the producer–consumer and decomposer relationships supports ecosystem engineers that link geo and biodiversity. The functional interactions among the biodiversity and geodiversity components create ecosystem diversity that is the driver of whole system properties.

We suggest that the web of interaction approach can potentially be applied to understand whole system emergent properties of terrestrial ecosystem.
Urban soils and human health
Authors: Bini Claudio , Wahsha Mohammad
Published: March 2020

Since the dawn of civilization, the anthropic activity has lead to a legacy of increased land degradation/contamination. Potentially harmful elements (PHEs) are among the most effective environmental contaminants, and their release into the environment is rising since the last decades. Interest in trace elements has been increased as a major scientific topic over the last 50 years when it was realized that some elements were essential to human health (e.g., Fe, Cu, Zn). In contrast, some others were toxic (e.g., As, Hg, Pb), and likely responsible for serious human diseases and lethal consequences. Since that time, great progress in knowledge of links between environmental geochemistry and human health has been achieved. The urban environment (nowadays the main habitat for the human population) is a potential PHEs source, with high risk for residents’ health. Indeed, PHEs concentration and distribution are related to traffic intensity, distance from roads, local topography, and heating. Industrial emissions also contribute to the release of toxic elements. Understanding the extent, distribution and fate of PHEs in the urban environment is therefore imperative to address the sustainable management of urban soils and gardens in relation to human health.

Despite the extensive researches addressed to this topic, the effects of most trace metals on human health are not yet fully understood. Uncertainty is still prevailing, particularly with non-essential elements that are “suspected” to be harmful to humans, causing severe health problems as intoxication, neurological disturbances and also cancer. Some of them (e.g., As, Cd, Hg, Pb) have attracted most attention worldwide due to their toxicity towards living organisms. Other elements (Al, B, Be, Bi, Co, Cr, Mn, Mo, Ni, Sb, Sn, Tl, V, W) are likely harmful, but may play some beneficial functions not yet well known, and should be more investigated.

Keywords: Urban soils; PHEs; Human health
Birth of a large volcanic edifice offshore Mayotte (Comoros Island, Western Indian Ocean)
Authors: Feuillet Nathalie , Jorry Stephan , Crawford Wayne , Deplus Christine , Thinon Isabelle , Jacques Eric , saurel Jean-Marie , Lemoine Anne , Paquet Fabien , Satriano Claudio , Aiken Chastity , Laurent Angèle , Cathalot Cecile , Rinnert Emmanuel , Gaillot Arnaud , Scalabrin Carla , Moreira Manuel , Peltier Aline , Beauducel François , Ballu Valerie ,   Tellus SISMAYOTTE and MAYOBS Team
Published: March 2020

Volcanic eruptions are foundational events shaping the Earth’s surface and providing a window into deep Earth processes. We document here an ongoing magmatic event offshore Mayotte island (Western Indian Ocean) unprecedented in terms of emitted volume of lava and duration of the seismic crisis.This event gave birth to a deep-sea volcanic edifice 820m tall and ~ 5 km3 in volume, located 50 km from Mayotte. A plume with distinct chemical signatures compared to open-ocean seawater emanated from the edifice, generating an exceptional 1900m-high vertical acoustic anomaly in the water column. Noble gas analyses in the vesicles from a popping rock dredged on the flank of the edifice, indicate rapid magma transfer from the asthenosphere. The edifice is located at the tip of a WNW-ESE–striking volcanic ridge composed of many other edifices, cones and lava flows constructed by past eruptions. Starting in May 2018 thousand of earthquakes were triggered by the magmatic event. The space-time distribution of the seismicity suggests that magma below the center of the ridge was transported to the new edifice over a few weeks in dikes that penetrated the brittle mantle a result of a lithosphere-scale extensional episode accommodating motion along a transfer zone between the East-African rifts and Madagascar. Since the eruption’s onset, the seismicity is mostly concentrated closer to the island, in an exceptionally deep zone (25-50 km) overlain by a zone of enigmatic, very low frequency, tremors.
Source location and evolution of the 26 s microseism from 3-C beamforming
Authors: Bruland Charlotte , Mader Sarah , Hadziioannou Céline
Published: March 2020

Source location and evolution of the 26 s microseism from 3-C beamforming

Authors: Charlotte Bruland1, Sarah Mader2, Céline Hadziioannou1
1 Institut für Geophysik, Universität Hamburg, Germany
2 Karlsruher Institut für Technologie, Karlsruhe, Germany

The interest in ambient noise has increased in the recent years due to its applications in imaging and monitoring the subsurface without the use of an active source. One of the major unknowns in this field is the origin of the noise used for these analyses. Better constraints on the location and behavior of noise sources will help us understand the ocean-solid Earth interaction processes driving them and improve our applications of ambient noise. One of the most enigmatic noise sources is the 26 s microseism. This very monochromatic source has been identified in the 1960’s and seems to come from a fixed location in the Gulf of Guinea. The source mechanism of this signal is unknown.

To investigate the origin and physical mechanisms responsible for the 26 s microseism, data from permanent broadband stations in Germany, France and Algeria, and temporary arrays in Morocco and Botswana is used for spectral analysis and 3-component beamforming. The source exhibits a strong temporal variation in spectral amplitude. The signal is not always detectable, but occasionally it becomes so strong it can be detected on stations all around the world. Such burst events can last for a couple of hours up to a couple of days. From January to April 2013, the peak was detected globally 28 percent of the time. The beamforming results confirm that the energy is coming from the Gulf of Guinea, as shown in previous studies, and the direction is temporally stable. Whenever the signal is detectable, both Love and Rayleigh waves are generated. Looking into the 26 s microseism over different time periods and using different arrays, the source is expected to be temporally stable in frequency and location, but varying in energy.
Transfer learning applications in hydrologic modeling
Authors: Hamman Joseph , Bennett Andrew
Published: March 2020

Early work in the field of Machine Learning (ML) for hydrologic prediction is showing significant potential. Indeed, it has provided important and measurable advances toward prediction in ungauged basins (PUB). At the same time, it has motivated a new research targeting important ML topics such as uncertainty attribution and physical constrains. It has also brought into question how to best harness the wide variety of climatic and hydrologic data available today. In this work, we present initial results employing transfer learning to combine information about meteorology, streamflow, surface fluxes (FluxNet), and snow (SNOTEL) into a state of the art ML-based hydrologic model. Specifically, we will present early work demonstrating how relatively simple implementations of transfer learning can be used to enhance predictions of streamflow by transferring learning from flux and snow station observations to the watershed scale. Our work is shown to extend recently published results from Kratzert et al. (2018) using the CAMELS data set (Newman et al. 2014) for streamflow prediction in North America.

Kratzert, F., Klotz, D., Brenner, C., Schulz, K., and Herrnegger, M.: Rainfall–runoff modelling using Long Short-Term Memory (LSTM) networks, Hydrol. Earth Syst. Sci., 22, 6005-6022, https://doi.org/10.5194/hess-22-6005-2018, 2018a.

Newman; K. Sampson; M. P. Clark; A. Bock; R. J. Viger; D. Blodgett, 2014. A large-sample watershed-scale hydrometeorological dataset for the contiguous USA. Boulder, CO: UCAR/NCAR. https://dx.doi.org/10.5065/D6MW2F4D
Development of criteria to improve water use efficiency in tomato crop (Solanum lycopersicum L.) under greenhouse in Ecuador
Authors: Rodriguez-Sinobas Leonor , Colimba-Limaico Javier Ezequiel , Zubelzu Sergio
Published: March 2020

Tomato (Solanum lycopersicum L.), grown under greenhouse in Ecuador, has a major weight in the farmers’ income in regions with water scarcity. In the one hand, these areas show  small water  use efficiency  caused by the non-technical criteria in the design of drip irrigation systems. On the other hand, farmers are unknown of the tomato water requirements, and do not know how to determine them. Moreover, they do not know how much water apply and the irrigation frequency depends on the availability of farmers’ time. In addition, in most cases greenhouses are lacked of equipment to measure climatic conditions.

This study evaluates different irrigation strategies, and its efficiency in the use of water, in the cultivation of tomatoes under greenhouse. It considers also they effect on the production and organoleptic quality of the fruit (size, dry matter and number of fruits). The methodology, first estimates the tomato water needs which was developed through the measures taking with practical and affordable equipment for farmers in the area. Then, the optimal water depth for irrigation was estimated on a daily basis application. Likewise, two factors were evaluated:  number of irrigations per day (one or two) and water depth (80%, 100%, 120% of crop evapotranspiration, and the one applied by local farmers). Thus, the combination of the two factors resulted in eight irrigation strategies which were implemented in irrigation plots following a randomized block design with four repetitions. The evaluation was accomplished in the four crop harvest over one year. The results helped to develop sustainable irrigation criteria for tomato crop under greenhouse in the area. These have improved water use efficiency, and maintained the production and quality of the fruits, which will  be beneficial not only for the farmers’ income but also in agriculture's resilience .
A sediment budget approach to quantify sediment fluxes and organic carbon mobilisation in an Arctic catchment
Authors: Matthews Francis , Hales Tristram C. , Ahmed Joshua
Published: March 2020

High Arctic erosion processes coupled with physical and chemical mobilisation of abundant soil organic carbon (SOC) stocks may play a critical role in driving Arctic biogeochemical cycles. The role of internal catchment dynamics such as detachment, transport, and colluvial/alluvial storage in controlling the generation, recycling, and export of sediment and SOC is poorly understood. We formulate a sediment and carbon budget for the 8140 km2 Alaskan Kuparuk Catchment using a 1985-2017 Landsat NDVI imagery record to delineate bank erosion and Google EarthTM to map landslide events. We calculate: 1) average inputs of sediment by alluvial bank erosion and landslides (including active layer detachments and thaw slumps), 2) transport fluxes from landslide deposits by spatially modelling fluvial transport capacity, and 3) total outputs from a record of suspended sediment collected at the catchment outlet. We calculate carbon export by estimating carbon erosion using the concentration of SOC as calculated by the Northern Circumpolar Soil Carbon Database. Alluvial bank erosion (0.6 ± 0.12 Tg yr−1) exceeded catchment sediment yield by an order of magnitude (0.06 Tg yr−1), demonstrating that recycling of sediment between floodplains, bars, and channels dominates the sediment budget of this catchment. Landslides are the dominant input of new sediment to the system, contributing 11 Tg of sediment (17 Tg including channel-disconnected). When considering the average export rate from transport-limited landslide deposits, this flux (between 0.008 and 0.4 Tg yr−1) is in near equilibrium with the average annual flux from the catchment (0.06 Tg yr−1). SOC inputs from bank erosion (932 t yr−1) explained the majority of estimated 1505 ± 114 t yr−1 POC outputs. Our work demonstrates that the annual erosion and redeposition of sediment in Arctic permafrost catchments greatly exceeds net export. Current measurements of sediment fluxes in a warming Arctic considerably underestimate total sediment and SOC mobilisation from carbon rich active layers.
The Role of Field-Aligned Current Closure on the E and F-Region Coupled Thermosphere-Ionosphere
Authors: Billett Daniel , McWilliams Kathryn , Conde Mark
Published: March 2020

In this study, the behaviour of both E and F-region neutral winds are examined in the vicinity of intense R1 and R2 field-aligned currents (FACs), measured by AMPERE. This is achieved through the dual sampling of both the green (557.5nm) and red (630nm) auroral emissions, sequentially, from a ground based Scanning Doppler Imager (SDI) located in Alaska.

With the addition of plasma velocity data from the Super Dual Auroral Radar Network (SuperDARN) and ionospheric parameters from the Poker Flat Incoheerent Scatter Radar (PFISR), we assess how the large closure of Pedersen currents (implied by the strong FACs) modifies the spatial and temporal structure of the neutral wind at different altitudes. We find that the thermosphere becomes significantly height dependent, which could indicate a broader altitude range where the Pedersen conductivity is more important during intense FAC closure.
Assessing several downscaling methods for daily minimum and maximum temperature in a mountainous area. Are we able to statistically simulate a warmer climate in the Pyrenees?
Authors: Lemus-Canovas Marc , Brands Swen
Published: March 2020

Mountain areas are one of the most vulnerable areas to climate change, due to the large amount of natural resources they contribute to society. Moreover, the announced increase in temperature for the next few decades may have uncertain consequences for the ecosystems and landscapes of such territories. To face this challenge, it is necessary to test the capacity to simulate the climate of warm periods using observed data. In the present contribution, different perfect prog (PP) downscaling methods were evaluated to simulate the minimum and maximum daily temperature in a 1x1 km grid in the Pyrenees (Spain, France & Andorra) for the period 1985-2015. To obtain the results, several combinations of predictors, different geographical domains of such predictors, as well as different reanalysis databases were used, to check how much they can influence the prediction skill. In addition, different metrics were calculated to evaluate the bias, the similarity in the observed and predicted distributions, the temporal correlation, etc.

The results obtained reflect that the regression models better represent the warm periods using the observed data, as well as a lower bias. The present study will facilitate the decision making on which method of downscaling PP is more useful to reproduce the future temperature in the Pyrenees.

 

Keywords: Statistical downscaling, perfect prog, Pyrenees, daily temperature.
Relating ASCAT backscatter and dynamic vegetation parameters to vegetation water dynamics in the Amazon
Authors: Petchiappan Ashwini , Steele-Dunne Susan , Vreugdenhil Mariette , Hahn Sebastian , Wagner Wolfgang
Published: March 2020

The Amazon rainforest is among the most vital ecosystems on earth, holding about a quarter of the global terrestrial carbon sink. Since 2005, three 100-year return period droughts have occurred, the likes of which have the potential to turn the forest from a carbon sink to a carbon source. Monitoring the Amazon is essential to understand the functioning of the various ecoregions and how they respond to water stress. 

In this study, we investigate the ASCAT backscatter and dynamic vegetation parameters (DVP) over the Amazon region as a potential source of information about the vegetation. The dynamic vegetation parameters are slope and curvature of the second order Taylor polynomial used to represent the incidence angle dependence of backscatter. We looked for spatial and temporal patterns in the backscatter and DVP over Amazonia, and related them to climatic variables such as radiation and precipitation from the Princeton Global Meteorological Forcing Dataset, as well as variations in terrestrial water storage from GRACE. 

Results will be presented from the first ten years of ASCAT observations over the Amazon region, including the Cerrado grasslands southeast of the Amazon forest. We found that spatial patterns of the backscatter and ASCAT DVP reflect the distribution of major land cover types in the region. Seasonal variations in the parameters match the seasonality of moisture demand and availability, and show an influence of vegetation phenology. Diurnal differences in backscatter between the morning (~10:00 AM) and evening overpasses (~10:00 PM) suggest that the backscatter is sensitive to vegetation water dynamics. Significant anomalies were observed during the Amazon droughts of 2010 and 2015, indicating that ASCAT could detect water stress and drought effects in the vegetation. Therefore, the ASCAT DVP show promise for long-term monitoring of the Amazon with respect to vegetation water dynamics and droughts. 
Glacier mapping with Sentinel-2 in Svalbard: Challenges when creating a new glacier inventory in the Artic
Authors: Paul Frank , Rastner Philipp
Published: March 2020

Svalbard is dominated by large (often calving) glaciers and ice caps with a strong contribution to global sea-level rise. Due to many surge-type glaciers, large changes of glacier extents are common and determination of their mass balance requires a regular update of their outlines. However, frequent cloud cover prevents accurate repeat mapping. In consequence, the last glacier inventory for Svalbard was compiled from satellite scenes acquired over a period of 11 years, making change assessment and other applications difficult. Due to long-lasting seasonal snow and confusion with large perennial snow patches, the minimum size of this inventory has been set to 1 km2.

Here we present a new glacier inventory for Svalbard that has been compiled at 10 m resolution from two Sentinel-2 scenes that were acquired only two days apart. Sea ice, ice-bergs, lakes and turbid water were wrongly classified as glaciers by the applied band ratio method and manually removed. Debris cover, snow and ice under some clouds but also polluted (very dark) clean ice was not mapped as thresholds were optimized to get snow and ice in shadow properly mapped. These missing regions were manually added. Snow patches were removed with a 5 by 5 majority filter applied to the binary glacier map and a minimum size of 0.05 km2. Outlines from the previous inventory as available in the RGI were used to guide the corrections. After careful comparison, we used the Arctic DEM to derive surface drainage divides and topographic attributes for all glaciers.

The largest challenges for accurate glacier delineation are discrimination of debris-covered glaciers from peri-glacial debris and rock glaciers, handling of attached seasonal or perennial snowfields, and identifying disintegrating tongues of down-wasting and often debris-covered ice masses remaining after a surge. Compared to the previous inventory, the large area gains and losses of surge-type glaciers are remarkable, but area differences result also from a different interpretation of debris-covered glaciers, inclusion of snow-filled couloirs and several new glaciers that were excluded in the previous inventory.
Multispectral reflectance vegetation indices are highly sensitive to water stress in grapefruit trees
Authors: Berrios Pablo , Temnani Abdelmalek , Pérez David , Gil Ismael , Zapata Susana , Forcén Manuel , Ramos Tiago B. , Santos Filipe N. , López Riquelme Juan Antonio , Pérez-Pastor Alejandro
Published: March 2020

The sensitivity to water stress of different plant water indicators (PWI) at different plot scales (leaf and aerial) was evaluated during the second fruit growth stage of grapefruit (Citrus paradisi cv. Star Ruby) trees growing in a commercial orchard for a sustainable irrigation scheduling. Trees were drip-irrigated and submitted to two irrigation treatments: (i) a control (CTL), irrigated at 100% of crop evapotranspiration to avoid any soil water limitations, and (ii) a non-irrigated (NI) treatment, irrigated as the control until the 104 days after full bloom (DAFB) when the irrigation was suppressed, until to reach a severe water stress level in the plants (around -2.3 MPa of stem water potential at solar midday). The plant water indicators studied were: stem water potential (SWP); leaf conductance (Lc); net photosynthesis (Pn), and several vegetation indices (VI) in the visible spectral region derived from an unmanned aerial vehicle equipped with a multispectral sensor. The measurements were made at 9, 12 and 18h (solar time) on 50 and 134 DAFB, coinciding with a fruit diameter of 20 and 70 mm, respectively. The correlation analysis between the PWI at leaf scale (SWP, Lc and Pn) and at aerial scale showed relatively poor results, with Pearson correlation coefficients (r values) around 0.6. However, SWP presented the highest r value with the normalized difference vegetation index (NVDI), green index (GI), normalized difference greenness vegetation index (NDGI) and red green ratio index (RGRI) showing the higher coefficients 0.80, 0,80, 0.85 and 0.86, respectively. In addition, a quadratic regression curve fitting was made for the SWP and aforementioned indices, obtaining values ​​of R2 around 0.7 in all cases; the best fit corresponded to SWP = - 4.869 + 15.765 NDGI - 14.283 NDGI2 (R2 = 0.749) to predict SWP values between -0.5 and -2.3 MPa. Results obtained show the possibility of using certain vegetation indices to be used in the detection of water stress in adult grapefruits, and thus propose a sustainable and efficient irrigation scheduling.

Funding:

-WATER4EVER is funded by the European Commission under the framework of the ERA-NET COFUND WATERWORKS 2015 Programme

-RIS3MUR REUSAGUA is funded by the Consejería de Empresa, Industria y Portavocía of the Murcia Region under the Feder Operational Program 2014-2020
Phobos composition: a reappraisal, based on Omega/MEx observations
Authors: Gondet Brigitte , Bibring Jean-Pierre
Published: March 2020

The imaging spectrometer OMEGA [1] operates in the VIS-NIR range, covering the (0.35 µm to 5.1 µm) range in 352 contiguous spectral channels.  This spectral range has been chosen as it includes diagnostic signatures of most surface mafic and hydrated minerals, frosts and ices. With a 1.2 mrad IFOV, the footprint varies from 40 m when imaging from 40 kms, up to 4.8 km from an altitude of 4000 km: this allows a global spectral coverage of Phobos to be achieved, at various spatial resolution.

Along its 16 years of orbital operations, Mars Express has performed tens of close flybys of Phobos, at altitudes down to ~ 50 kms. OMEGA has acquired unprecedented compositional data sets, in both the visible and the near-infrared spectral range. We shall present and discuss these observations, as witnesses of Phobos origin, with their relevance to the upcoming MMX JAXA mission.
Staudamm – a serious game on water reservoir management
Authors: Vis Marc , van Meerveld Ilja , Seibert Jan
Published: March 2020

Serious games can be useful to teach students about real-world challenges. Here we present a first prototype of the online game 'Staudamm'. In this game, each player operates a multi-purpose water reservoir. The goal is to optimize revenues from the dam by balancing flood protection, electricity production, and irrigation-water supply, while fulfilling the minimal requirements for environmental flows. For flood protection, an almost empty reservoir would be optimal, whereas for electricity production and irrigation-water supply a fully filled reservoir would be preferable for at least at some time during the year. While there are some seasonal patterns in the inflows to the reservoir, balancing the different objectives is difficult, as one never exactly knows how much water will enter the reservoir. The game illustrates the difficulty in balancing multiple objectives, as well as the use of uncertain predictions in decision-making. In this poster presentation, we present the first prototype of the game and ask for suggestions for improvements and extensions.
Antarctic Circumpolar Current Biases in a hierarchy of HadGEM3-GC3.1 Models
Authors: Jonathan Tomas , Johnson Helen , Marshall David , Bell Mike , Hyder Patrick
Published: March 2020

The Southern Ocean is a crucial part of the global ocean circulation. The unique bathymetry and lack of meridional boundary in conjunction with an equator to pole temperature gradient and strong westerly winds results in an eastward flowing Antarctic Circumpolar Current (ACC). The ACC is the strongest ocean current in the world (173.3 ± 10.7Sv), vital in transporting heat, carbon and nutrients between the major ocean basins. 

Using prototype UK CMIP6 (HadGEM3-GC3.1) simulations at 1°, 1/4° and 1/12° spatial resolutions we illustrate the strong resolution dependence of the strength of the ACC through the Drake Passage. All three model resolutions exhibit a weak ACC compared to observations. The 1/4° and 1/12° models show a significant weakening over the first 50 years, stabilizing at 60Sv and 120Sv respectively.

We analyse the source of the weaker volume transport by decomposing the ACC transport into components arising due to northern and southern boundary density profiles (relative to the bottom density), Ekman transport and depth-independent flow. We attribute the weaker ACC in the 1/4° model to a lightening of the southern density profile and the formation of a reverse flow along the coast of Antarctica.

Our decomposition highlights the significant contribution to the ACC’s volume transport and variability made by both northern and southern density profiles, as well as the depth-independent component of the flow.
Evolution of future extreme drought frequency in two climate model large ensembles
Authors: Zhao Cha , Brissette François , Chen Jie , Martel Jean-Luc
Published: March 2020

Recent studies project a significant increase in drought frequency over most continents over the 21st century. However, few studies have specifically looked at extreme droughts, defined here as having a return period larger than 20 years. In this work, two large climate model ensembles, the 50-member Canadian Earth System Model (CanESM2) and the 40-member Community Earth System Model (CESM1), both under the RCP8.5 scenario are used to project the evolution of the extreme drought frequency in the near (2036-2065) and far future (2070-2099) relative to the 1980-2009 historical period. The use of a large ensemble allows for a robust estimation of the frequency of very large droughts. Frequency changes for the 2, 20 and 100-year droughts were computed.

Extreme meteorological droughts were globally assessed using the short-term (1-month) and long-term (24-month) Standardized Precipitation Index (SPI). Extreme hydrological extreme droughts were assessed by the 1-month Streamflow Drought Index (SDI), using a lumped hydrological model on 5797 North American catchments to transform climate model outputs into catchment streamflows.

Results show that both climate models project increases of extreme meteorological drought frequency over many of the world’s regions, with a typical two or three-fold increase. The spatial distribution of regions with increasing meteorological drought frequency mostly matches those projected changes in future mean annual precipitation. Changes in future extreme hydrological droughts are dramatically more severe than for meteorological droughts, with up to a 27-times increase in frequency for the 100-year hydrological droughts, outlining the large impact of temperature change. The frequency change is the largest for the 100-year compared to the 2 and 20-year hydrological droughts.
Quantifying the impact of climate change on floods by using both continuous and event-based hydrological modelling
Authors: Soriano Martín Enrique , Mediero Orduña Luis , Garijo Sarria Carlos
Published: March 2020

Climate change will modify magnitude and timing of floods in the future. Consequently, new methodologies to quantify the impact of climate change on floods at the catchment scale are required. This study aims to quantify the changes in peak flow quantiles expected in the future, by using the climate change projections of the Fifth Report (AR5) of the IPCC, supplied by the EURO-CORDEX programme. Four catchments located in the Duero River Basin in northwestern Spain are considered as case studies.

 

First, biases in precipitation and temperature climate projections have been corrected by using the available observations in the control period (1971-2004) in the four catchments. Second, the hydrological response in the four catchments has been simulated with the continuous simulation model HBV. The model has been calibrated in the four catchments. Time series of soil moisture content in the catchment were obtained, identifying the initial moisture content in the day of occurrence of the annual maximum rainfalls. Third, an event model has been used to simulate flood response to the annual maximum rainfalls, considering the initial soil moisture content supplied by the HVB model. The results of the event model provides a better characterization of the catchment flood response than the continuous HBV model.

 

The methodology has been applied in the control period (1971-2004), for validation purposes. Then, the methodology has been applied to the future period (2011-2095), to obtain the expected changes in peak flow quantiles, as a consequence of climate change. The combined use of the results of the continuous hydrological simulation with the HBV model with the event model improves the results provided by either the HBV model or the event model independently. The proposed methodology allows a better characterisation of the catchment flood response to a given precipitation event, while also considering the expected variation in the antecedent moisture content in the catchment in the future, as a consequence of expected changes in temperature and precipitation regimes. The application of the proposed methodology to the case studies has shown that climate change will increase peak flow quantiles in the future, in three of the four catchments.
Stable isotopes as early indicators of high impact after plant invasion: A remote sensing perspective
Authors: Große-Stoltenberg André , Hellmann Christine , Thiele Jan , Oldeland Jens , Werner Christiane
Published: March 2020

High impact invasive plant species, such as the N-fixing and water-spending tree Acacia longifolia, are a major threat to ecosystem functioning worldwide. For example, Acacia's impact on nutrient and water-cycling in Mediterranean dune ecosystems is well understood. However, early detection of such impacts remains challenging. Therefore, novel approaches are required to map functional indicators of high invader impact. Here, we tested in a real world context if the stable isotopes δ13C and δ15N could be such mappable indicators. First, we show that A. longifolia differs regarding its biochemical leaf traits from the native species of the same growth form particularly regarding leaf N content as well as δ13C and δ15N. This may indicate a high impact on N and water cycling, and can be retrieved from hyperspectral data. Second, the impact of the invader on N cycling was mapped joining the spatial distribution of δ15N with airborne laserscanning data. Foliar δ15N of a non-fixing, native species increased in vicinity of invasive stands indicating an uptake of N previously fixed by the invader. Finally, those impacts possibly result in an increase of productivity of the whole dune ecosystem even when invader cover is low. This increase can be mapped integrating hyperspectral imagery with LiDAR data. Thus, there is potential to retrieve functional indicators of high impact including stable isotopes using remote sensing.
Biogeochemical analysis of newly dated lacustrine cores: a first look at Quaternary paleoenvironment in coastal Mozambique
Authors: Skosey-LaLonde Elena , Gomes Ana , Martins Maria João , Connor Simon , Raja Mussa , Zinsious Brandon , Matias Roxane , Mauelele Reginelinda , Haws Jonathan , Moura Delminda , Hartman Gideon , Gonçlaves Célia , Cascalheira João , Oliveira Sónia , Fernandes Paulo , Costas Susana , Bicho Nuno
Published: March 2020

In order to better quantify the role of climate variability in southeastern Africa, and its impact on the evolution and spread of anatomically modern humans, our international and interdisciplinary team cored a series of coastal lakes during the summer of 2019. Here, we present data from lake Nyalonzelwe, one of many interdunal lakes present along the coast in the Inhambane region of southeastern Mozambique. Nyalonzelwe sits 5m above MSL and is bounded by a Pleistocene dune system, reaching between 29-121m in elevation, protecting the lake from the Indian Ocean. The sedimentological record of Nyalonzelwe presents over 6m of stratigraphic variability, including a varve sequence spanning the basal 2m, making it an incredibly rare record of seasonal resolution climate variability and the first record of its kind in Mozambique. Two cores, C1 and C4, with depths of 6.12m and 6.22m respectively, were collected for multiproxy biogeochemical analyses and C14 dating using a Livingstone corer. This work seeks to present the results of Carbon, Hydrogen, Nitrogen (CHN) elemental analysis for core C1, sampled at 10 cm intervals and aragonite/calcite ratios for gastropod assemblages across C4, sampled at 1 cm resolution in preparation for stable isotope analysis.

CHN analysis was conducted using an Elementar model Vario EL III at the University of Algarve CCMAR for both organic and inorganic carbon present in sediment samples from C1. Aragonite/calcite ratios for identified gastropod species, namely Melanoides tuberculata, were collected from individual representatives in samples from C4 with more than 8 individuals present and determined using Fourier Transform Infrared Spectroscopy at the University of Connecticut. Nyalonzelwe cores C1 and C4 are stratigraphically correlated. Together these data represent the first look at Quaternary paleoenvironmental evolution in southeastern coastal Mozambique and the importance of climate (in)stability in the region and its impact on early modern human populations. This work was supported by the project PTDC/HAR-ARQ/28148/2017, funded by the Portuguese Foundation for Science and Technology.
Does “Alpine Pumping” have an effect on the ventilation of Munich?
Authors: Sedlmeier Katrin , Koßmann Meinolf , Winderlich Kristina , Graf Maximilian , Mühlbacher Gudrun
Published: March 2020

Alpine Pumping refers to a thermally driven circulation between the Alps and the Alpine foreland in southeastern Germany, which occurs regularly under clear and calm weather conditions (e.g. Lugauer and Winkler (2005)). Earlier studies suggest, that the ventilation of the city of Munich, and thus the urban temperature distribution, could be influenced by this regional wind system.

The present work was conducted in a cooperation framework between the city of Munich and the German Meteorological Service. The occurrence of Alpine Pumping and its effect on the temperature distribution in the city of Munich were investigated by temporary and operational wind measurements as well as numerical simulations. The thermal wind system was simulated with the regional climate model COSMO-CLM and the characteristics of Alpine Pumping deduced from this simulation used as input for the high-resolution urban climate model MUKLIMO_3.

Using a radiation-based criterion, Alpine Pumping occurs on about 60 days per year, mostly in the summer months when the heat load is highest. The wind fields of temporary measurements in the rural areas south of Munich show the expected daily cycle of the wind system, especially the southerly flow during the night, which transports cold air from the mountains into the city. An influence of the regional circulation pattern on the temperature in the city area was found in a case study with the urban climate model MUKLIMO_3. Especially at night and in the morning hours, the cooler air from the surroundings ventilates the city area. Furthermore, the model results show a spatial shift of the maximum heat island in Munich during the course of the day.

The findings show, that Alpine Pumping is a rather frequent phenomenon in the study area and represents an important contribution to the natural ventilation of different areas within the city.

 

References:

LUGAUER, M., WINKLER, P., 2005: Thermal circulation in South Bavaria - climatology and synoptic aspects. Meteorologische Zeitschrift. 14, 15-13.
Enceladus geyser study using Markov Chain Monte Carlo fits of DSMC simulations
Authors: Goldstein David , Mahieux Arnaud , Varghese Philip , Trafton Laurence
Published: March 2020

The two-phase water plumes arising from the Enceladus South pole and extending hundreds of km from the moon are a key signature of what lies below the surface. Multiple Cassini instruments measured the gas-particle plume over the warm Tiger Stripe region during several close flybys. A lot of work has been put into constraining the vent and flow characteristics, such the vent positions and orientations, the mass flows, speeds and temperatures.
The most likely source for these extensive geysers is a subsurface liquid reservoir of somewhat saline water and oth-er volatiles boiling off through crevasse-like conduits into the vacuum of space. The plumes thus provide a window for understanding Enceladus’ subsurface composition and geysering.
We used a DSMC code to simulate the plume, as it exits a vent, under axisymmetric conditions, in a vertical domain extending up to 10 km, where the flows become collisionless. We performed a DSMC parametric study of the flow parameters considering the following eight parameters: vent diameter, outgassed flow density, water vapor/ice mass ratio, gas and ice speed, ice grain diameter, temperature and vent exit angle.
We constructed parametric expressions for the plume characteristics – number density, temperature, velocity compo-nents – using simple analytic expressions to depict the constrained surfaces of these parameter values, at the 10 km upper boundary.
We use these parametrizations to propagate the plumes to higher altitudes – up to thousands of km – assuming free-molecular conditions. The density field at higher altitude is determined from the parametrizations described above, and explicit analytical expressions for the various force fields that the plumes are experiencing: Enceladus and Saturn gravity fields, Coriolis and centripetal accelerations due to Enceladus rotation.
This split domain approach enables rapid numerical computations – ~10 minutes – and tabulations of the density and velocity fields in space.
We then performed a formal Monte Carlo sensitivity analysis of twelve vent parameters – the ones cited above plus vent latitude, longitude, azimuth and zenith angles of the venting direction – conditioned on the number density field measured by the INMS instrument, considering the 98-vent geometry reported in Porco et al. (2014). The sensitivity analysis is used to determine which vent parameters should be considered for a subsequent fit of the INMS observa-tion. We present an advanced way to constrain the vent parameters by performing a Markov Chain Monte Carlo search that returns probability values for the preselected vent parameters, considering a few INMS observations. This ap-proach allows us to constrain many vent parameters (up to a few hundreds), and, uniquely, return probability distri-bution for each of them.
Socio-economic determinants of land use/cover change in wetlands in East Africa: a case study analysis of the Anyiko wetland, Kenya
Authors: Ajwang Risper , Vuolo Francesco , Kipkemboi Julius , Kitaka Nzula , Lautsch Erwin , Hein Thomas , Schmid Erwin
Published: March 2020

In East Africa, wetlands are steadily converted to agriculture for food security reasons. This study analyzed high spatial resolution panchromatic and color photographs in the Anyiko wetland in Kenya to reveal wetland conversions between 1966 and 2018. Socio-economic determinants of land use/cover change are also assessed in the Anyiko wetland. Socio-economic data was collected through a questionnaire survey of 226 households. A CHi- squared Automatic Interaction Detector (CHAID) decision tree approach is utilized to assess determinants of wetlands conversion. The results showed that between 1966 and 2018, the wetland area reduced by 55%, mostly attributed to agricultural development. Households were more likely to cultivate the wetland if they did not harvest papyrus for artisanal products, were male-headed and lacked alternative sources of income. The perceptions that wetland is “wasteland” and conversion to agriculture provides higher net monetary benefit did not influence wetland cultivation. Hence, the conversion of the wetland was determined by the socio-economic status of the households rather than perceptions on its value.
Paratethys pacing of the Messinian Salinity Crisis: low salinity waters contributing to gypsum precipitation?
Authors: Krijgsman Wout , Grothe Arjen , Andreetto Federico , Reichart Gert-Jan , Wolthers Mariette , van Baak Christiaan , Vasiliev Iuliana , Stoica Marius , Sangiorgi Francesca , Middelburg Jack , Davies Gareth
Published: March 2020

During the so-called Messinian Salinity Crisis (MSC: 5.97-5.33 Myr ago), reduced exchange with the Atlantic Ocean caused the Mediterranean to develop into a “saline giant” wherein ~1 million km3 of evaporites (gypsum and halite) were deposited. Despite decades of research it is still poorly understood exactly how and where in the water column these evaporites formed. Gypsum formation commonly requires enhanced dry conditions (evaporation exceeding precipitation), but recent studies also suggested major freshwater inputs into the Mediterranean during MSC-gypsum formation. Here we use strontium isotope ratios of ostracods to show that low-saline water from the Paratethys Seas actually contributed to the precipitation of Mediterranean evaporites. This apparent paradox urges for an alternative mechanism underlying gypsum precipitation. We propose that Paratethys inflow would enhance stratification in the Mediterranean and result in a low-salinity surface-water layer with high Ca/Cl and SO4/Cl ratios. We show that evaporation of this surface water can become saturated in gypsum at a salinity of ~40, in line with salinities reported from fluid inclusions in MSC evaporites.