bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface and aerosol retrieval from S5P and S4: baseline requirements and expected performance
Authors: Litvinov Pavel , Dubovik Oleg , Chen Cheng , Lopatin Anton , Lapionak Tatyana , Fuertes David , Karol Yana , Holter Christoph , Lanzinger Verena , Bindreiter Lukas , Hangler Andreas , De Graaf Martin , Tilstra Gijsbert , Stammes Piet , Retscher Christian
Published: March 2020

Sentinel-4 and Sentinel-5p instruments provide hyperspectral measurements in UV, VIS and infrared spectral range. Though the main purpose of the satellites is trace gas characterization, both instruments are capable of aerosol and surface characterization. In particular, S4 and S5p measurements in UV have unique information about absorption and elevation properties of aerosol. Moreover, measurements in wide spectral range are very sensitive to aerosol size and surface type. On one hand, aerosol and surface characteristics are important input parameters for different trace gases such as ozone, NO2, BrO, CH2O, H2O, CO2, CO, and CH4. On another hand, aerosol and surface characteristics are very important on their own for climate studies, air pollution and surface monitoring.

The quantitative characterization of aerosol (AOD (Aerosol Optical Depth), aerosol type) and surface properties (BRDF (Bidirectional Reflectance Distribution Function)) from Sentinel-4 and Sentinel-5p instruments is a topic for several ESA/EUMETSAT projects. In particular, in the framework of S5P+I AOD/BRDF project an innovative algorithm will be developed which integrates the advanced GRASP algorithm (Dubovik et al. 2011, 2014) with the heritage AOD and DLER algorithm previously applied to TOMS, GOME(-2), SCIAMACHY and OMI sensors (Tilstra et al., 2017). Innovative GRASP algorithm is expected to provide surface BRDF and AOD with the accuracy required by most trace gas retrieval algorithms.

Here the requirements on aerosol and surface characterization from S4 and S5p instruments will be analyzed. On the basis of inversion results from the synthetic (S4) and real (S5p) measurements we discuss how expected AOD and BRDF accuracy from the innovative and GRASP/S4 algorithms meet these requirements. New advanced possibility of aerosol and surface characterization with GRASP from S5p instrument will be discussed.

References

Dubovik, O., et al., “Statistically optimized inversion algorithm for enhanced retrieval of aerosol properties from spectral multi-angle polarimetric satellite observations”, Atmos. Meas. Tech., 4, 975-1018, 2011.

Dubovik, O., et al. “GRASP: a versatile algorithm for characterizing the atmosphere”, SPIE: Newsroom, doi:10.1117/2.1201408.005558, Published Online: http://spie.org/x109993.xml, September 19, 2014.

Tilstra, L. G., et al., “Surface reflectivity climatologies from UV to NIR determined from Earth observations by GOME-2 and SCIAMACHY”, J. Geophys. Res. Atmos., 122, 4084–4111.
The role of an Indian Ocean heating dipole in the ENSO teleconnection to the North Atlantic in early winter in the 20th century in observations and CMIP5 simulations
Authors: Kucharski Fred , Joshi Manish K. , Abid Mohammad Adnan
Published: March 2020

In this study the role of an Indian Ocean heating dipole anomaly in the transition of the North Atlantic circulation response to ENSO from early to late winter is analysed using 20th century observations and simulations from the fifth Coupled Model Intercomparison Project (CMIP5). It is shown that in early winter a warm (cold) ENSO even is connected trough an atmospheric bridge with positive (negative) rainfall anomalies in the western and negative (positive) anomalies in the eastern Indian Ocean. The early winter heating dipole teleconnected to a warm (cold) ENSO event can set up a wavetrain emanating from the south Asian subtropical jet region that reaches the North Atlantic and leads to response that spatially projects onto the positive (negative) phase of the North Atlantic Oscillation (NAO). The Indian Ocean heating dipole is partly forced as an atmospheric teleconnection by ENSO, but can also exist independently and is not related to local Indian Ocean SST forcing. The Indian Ocean heating dipole response to ENSO is much weaker in late winter (February and March) and not able to force significant signals in the North Atlantic region. CMIP5 models reproduce the early winter heating dipole reponse to ENSO and the ENSO response transition in the North Atlantic region to some extend, but with weaker amplitude. Generally models that have a strong early winter ENSO heating dipole teleconnection to the Indian Ocean also reproduce the North Atlantic response. If an Indian Ocean vertical velocity dipole index is defined, overall CMIP5 models are able to reproduce the extratropical responses in early winter reasonably well.
Comparing Halo Doppler lidar depolarization ratio with PollyXT
Authors: Vakkari Ville , O'Connor Ewan , Baars Holger , Bühl Johannes
Published: March 2020

Depolarization ratio is highly valuable in lidar-based aerosol classification and can be used to quantify the contributions of different aerosol types to elevated layers [1]. Typically, aerosol particle depolarization ratio is determined at relatively short wavelengths of 355 nm and/or 532 nm, though some multi-wavelength case studies including 1064 nm have shown strong spectral dependency [2,3]. Here, we demonstrate that Halo Photonics Stream Line Doppler lidars can be used to retrieve aerosol particle depolarization ratio at 1.5 µm wavelength.

 

We utilize measurements in April-May 2017 at Limassol, Cyprus to compare the Halo 1.5 µm aerosol particle depolarization ratio with Polly XT aerosol particle depolarization ratio. Recently developed post-processing [4] enables retrieving weak signals (as low as -32 dB) with the Halo Doppler lidar. At Limassol, we were able to determine particle depolarization ratio for several cases of mineral dust up to 3 km above ground. Generally, particle depolarization ratio for mineral dust at 1.5 µm appears higher than at shorter wavelengths of 355 nm and 532 nm retrieved by Polly XT. Overall, our results indicate that Halo Doppler lidars can add another wavelength at 1.5 µm to studies on the spectral dependency of aerosol depolarization ratio, at least in the lowest 2-3 km above ground.

 

[1] Mamouri, R.-E. and Ansmann, A.: Potential of polarization/Raman lidar to separate fine dust, coarse dust, maritime, and anthropogenic aerosol profiles, Atmos. Meas. Tech., 10, 3403-3427, https://doi.org/10.5194/amt-10-3403-2017, 2017.

[2] Burton, S. P., Hair, J. W., Kahnert, M., Ferrare, R. A., Hostetler, C. A., Cook, A. L., Harper, D. B., Berkoff, T. A., Seaman, S. T., Collins, J. E., Fenn, M. A. and Rogers, R. R.: Observations of the spectral dependence of linear particle depolarization ratio of aerosols using NASA Langley airborne High Spectral Resolution Lidar, Atmos. Chem. Phys., 15, 13453–13473, doi:10.5194/acp-15-13453-2015, 2015.

[3] Haarig, M., Ansmann, A., Baars, H., Jimenez, C., Veselovskii, I., Engelmann, R. and Althausen, D.: Depolarization and lidar ratios at 355, 532, and 1064 nm and microphysical properties of aged tropospheric and stratospheric Canadian wildfire smoke, Atmos. Chem. Phys., 18, 11847–11861, doi:10.5194/acp-18-11847-2018, 2018.

[4] Vakkari, V., Manninen, A. J., O’Connor, E. J., Schween, J. H., van Zyl, P. G. and Marinou, E.: A novel post-processing algorithm for Halo Doppler lidars, Atmos. Meas. Tech., 12(2), 839–852, doi:10.5194/amt-12-839-2019, 2019.
Studying heat waves and warm summers in numerical climate models with a rare event algorithm
Authors: Ragone Francesco , Bouchet Freddy
Published: March 2020

Extreme events are a major topic of interest in climate science. Studying rare extreme events with complex numerical climate models is computationally challenging, since in principle very long simulations are needed to sample a sufficient number of events to provide a reliable statistics. This problem can be tackled using rare event algorithms, numerical tools developed in the past decades in mathematics and statistical physics, dedicated to the reduction of the computational effort required to sample rare events in dynamical systems. Typically they are designed as genetic algorithms, in which a set of suppression and cloning rules are applied to an ensemble simulation in order to focus the computational effort on the trajectories leading to the events of interest. Recently we showed the great potential of rare event algorithms for climate modelling, applying a rare event algorithm to study extremes of European surface temperature in Plasim, an intermediate complexity model, in absence of external time dependent forcings (no seasonal and daily cycles). Here we go beyond these limitations, studying extreme heat waves and warm summers in the Northern extratropics in fully realistic conditions including daily and seasonal cycles, both in Plasim and in the state of the art Earth system model CESM. We show how the algorithm allows to sample extreme events characterised by persistency on different time scales, discussing links with large deviation theory. We show how one can characterise the statistics of heat waves and warm summers with extremely large return times, with computational costs orders of magnitude smaller than with direct sampling, and reach ultra rare events that would have been impossible to observe otherwise. We analyse the emergence of teleconnection patterns during the extreme events and their relation to the dynamics of planetary waves. Finally we discuss how these results open the way to the systematic application of these techniques to a vast range of applicative and theoretical studies.
Occurrence and mechanisms of extreme winter air temperatures in the Arctic and surrounding continents
Authors: Vihma Timo , Uotila Petteri , Naakka Tuomas , Nygård Tiina
Published: March 2020

The recent rapid warming of the Arctic atmosphere and ocean and related sea ice decline have been associated with increasing occurrence of extreme weather events in the Arctic. Applying ERA-Interim reanalysis, we identify 100 days with largest positive and negative anomalies (compared to local climatology) in 2-m air temperature (T2m) in the Northern Hemisphere in winter during 2005-2019, and address various physical mechanisms contributing to these events. The mechanisms responsible for warm extremes in the Arctic are often associated with a meandering Polar front jet stream, favouring cases of large transports of heat and moisture from mid-latitudes to the Arctic. In addition, subsidence heating often contributes to warm extremes in the Arctic, allowing them to occur also under high-pressure conditions. The coldest T2m anomalies north of 30oN mostly occur in regions that are also climatologically cold, i.e., cannot be strongly affected by cold-air advection. This suggests a dominating role local surface energy budget and boundary-layer processes.

Extreme weather events often interact with anomalies in sea ice concentration. Cases of strong winds transporting warm, moist air masses to the Arctic provide both dynamic and thermodynamic forcing for large sea ice anomalies, and during winter the openings in sea ice field contribute to air temperature extremes via large heat fluxes from the ocean to atmosphere.

Coldest winter extremes in mid-latitudes are typically associated with meandering jet stream and high-pressure blockings, but show differences between Central Europe, North America and northern China. In Central Europe the coldest events are typically associated with cold-air advection from the East or Northeast, whereas during the coldest events in North American East Coast the cold air is transported from the North. In northern China, the coldest events often occur under high-pressure conditions with weak winds. Accordingly, the role of cold-air advection is much smaller than in the case of the coldest events in North America.
The Heat beneath Our Feet
Authors: van Hunen Jeroen , Adams Charlotte , Gluyas Jon , de la Harpe Jonty , Hastie Karina , Norman Tom
Published: March 2020

While coal energy is phased out to decarbonise our energy supply, the water within flooded abandoned mines provide a huge source (2.2 million GWh) of geothermal heat for the future, enough to meet the UK’s heating demand for more than a century. The mine water is only lukewarm (12-20oC), but by using a heat pump, temperatures can be increased to a more comfortable 40-50oC. Heat pumps need electricity, but for every kW of electrical input, the heat output is 3-4 kW, making this an efficient energy source. Research has shown that our abandoned mines could meet our heat demands for a century or more, and will deliver economic opportunities to former mining areas.

After abstraction of water from the mine and subsequent heat extraction , the mine water is returned to the subsurface to avoid surface water contamination. Understanding the subsurface to ensure the right location(s) for re-injection of the water is crucial for the thermal evolution of the mine system. In addition, mine water could interact with nearby (potable) aquifers, so a proper understanding of the hydrogeological behaviour of the mined system is required. Therefore, numerical modelling of mine water and surrounding groundwater flow and associated heat exchange is an essential first stage for the successful deployment of these geothermal mine energy systems.

Here, we present numerical modelling results of the thermal evolution of mine water circulation systems. A parameter sensitivity study gives insight in the rate of heat depletion of the mines, and the importance of several model parameters, such as mine tunnel connectivity, mine water flow speed, and water re-injection location.

This project involves collaboration with the Coal Authority and Durham county council in the UK. Available mine plan data offer opportunities to apply the modelling to proposed mine energy sites across coalfields in the UK and further afield. Results will be applied for planned geothermal energy sites at Stanley (county Durham), South Tyneside and Blyth Port in north-east England.
Investigating the cost-efficiency of rewetting German organic soils
Authors: Steinhauser Jan
Published: March 2020

Degraded organic soils are the largest source of atmospheric CO2 outside the energy sector, responsible for five percent of Germany’s total greenhouse gas (GHG) emissions. Previous studies have shown a high potential of both protecting non-degraded soils and rewetting degraded soils for mitigating GHG emissions. However, these emission assessments provide little information about opportunity cost and regional cost-efficiency.

This study maps local emission benefits and management cost of organic soil restoration in Germany using a county-scale resolution (EU NUTS level 3/LAU level 1). We integrate these data in a recursive dynamic European agricultural sector model. This model determines the global agricultural market equilibrium for major agricultural commodities. In the European Union, the model depicts several intensities of crop and livestock production. To compute national abatement cost functions for rewetting organic soils in Germany, we solve the model for a wide range of alternative carbon prices applied to emission reductions from organic soils. From the optimal solution, we determine total emission reductions from organic soils in Germany accompanied by adjustments in agricultural production, land values, commodity prices, and international commodity trade.

The resulting spatial data will define economically attractive soil areas in Germany for agricultural mitigation efforts and for future in-depth case studies and stakeholder discussions. Thus, the results will guide optimal strategies for organic soil restoration.
What can we learn from single model initial-condition large ensembles (SMILEs)? A Comparison of Multiple SMILEs for Precipitation
Authors: Wood Raul R. , Lehner Flavio , Pendergrass Angeline , Schlunegger Sarah , Rodgers Keith
Published: March 2020

Identifying anthropogenic influences on climate amidst the “noise” of internal climate variability is a central challenge for the climate research community. In recent years, several modeling groups have produced single-model initial-condition large ensembles (SMILE) to analyze the interplay of the forced climate change and internal climate variability under current and future climate conditions. These simulations help to improve our understanding of climate variability, including extreme events, and can be employed as test-beds for statistical approaches to separate forced and internal components of climate variability.

So far, most studies have focused on either an individual or a  limited number of SMILEs. In this work we compare seven large ensembles to disentangle the influence of internal variability and model response uncertainty for multiple precipitation indices (e.g. wettest day of the year, precipitation with a return period of 20 years). What can we learn from intercomparison of SMILEs, how similar are they in terms of spatial patterns and forced response, and what if they aren’t? How does the forced response of an ensemble of SMILEs compare to the CMIP5 multi-model ensemble? By assessing multiple SMILEs we can identify robust signals for regional and global precipitation properties and revealing anthropogenic responses that are inherent to our current representations of the Earth system.
Field-aligned current ordering in ground and space measurements
Authors: Dunlop Malcolm , Yang Junying , Dong Xiangcheng , Freeman Mervyn , Rogers Neil , Wild Jim , Forsyth Colin , Cao Jinbin , Lühr Hermann , Xiong Chao
Published: March 2020

The orientation of field-aligned current sheets (FACs) can be inferred from dual-spacecraft correlations of the FAC signatures between two Swarm spacecraft (A and C), using the maximum correlations obtained from sliding data segments. Statistical analysis of both the correlations and the inferred orientations shows clear trends in magnetic local time (MLT) which reveal behaviour of both large and small scale currents. The maximum correlation coefficients show distinct behaviour in terms of either the time shift, or the shift in longitude between Swarm A and C for various filtering levels. The lower-latitude FACs show the strongest correlations for a broad range of MLT centred on dawn and dusk, with a higher correlation coefficient on the dusk-side and lower correlations near noon and midnight, and broadly follow the mean shape of the auroral boundary for the lower latitudes corresponding to Region 2 FACs (and are most well-ordered on the dusk side). Individual events sampled by higher altitude spacecraft (e.g. the 4 Cluster spacecraft), in conjunction with Swarm (mapping both to region 1 and 2), also show two different domains of FACs: time variable, small-scale (10s km), and more stationary large-scale (>100 km) FACs. We investigate further how these FAC regimes are dependent on geomagnetic activity, focusing on high activity events. Both the statistical trends, and individual conjugate events, show comparable effects seen in the ground magnetometer signals (dH/dt) during storm/substorm activity and show distributions that are similar.
Characterization of OVOC emission from wildfires using observations from Sentinel-5 Precursor
Authors: Alvarado Leonardo M. A. , Richter Andreas , Vrekoussis Mihalis , Hilboll Andreas , Kalisz Hedegaard Anna B. , Burrows John P.
Published: March 2020

Oxygenated volatile organic compounds (OVOCs) are released to the atmosphere from biogenic, anthropogenic, and pyrogenic sources. The role and importance of OVOCs in ambient atmospheric composition and their role in climate change was established many years ago. Another topical issue is the formation of secondary organic aerosols (SOA), which potentially are relevant for cloud formation, heterogeneous chemistry, and can also contribute to the long-term transport of volatile organic compounds. OVOCs can be detected from space-borne observations using the Differential Optical Absorption Spectroscopy (DOAS) method. Here, measurements from the TROPOMI instrument, which was launched on the Sentinel-5 Precursor (S5P) platform in October 2017, are used. 

During the year 2019, large wildfires occurred in North America, Amazonia, Siberia, and Australia. These fires created elevated amounts of many different gases, e.g. CO, NOx, OVOC, O3, SO2, CO, HONO, CH3CO.O2.NO2 (PAN) and other toxic species as well as aerosols affecting air quality. During the transport of plumes from fires, photochemical transformation of emitted species occurs. Overall, polluted air is transported to regions where the plumes are dispersed. For many of the fires, unexpectedly high amounts of OVOCs are detected in plumes as consequence of continued emission and conversion of some OVOCs. The amounts of OVOCs emitted were found to depended on the type of biomass burned and the location of the fires. 

Here, a characterization of OVOC emissions from fires is performed by using OVOC S5P observations, in combination with forward trajectories simulated with the FLEXPART model and proxies of vegetation types, leading to new insights in the emissions of OVOCs from fires.
Reconstruction of Holocene glacier fluctuations at Kongsbreen based on sediments deposited in lake Sarsvatnet, Ossian Sarsfjellet, Svalbard
Authors: Støren Eivind W. N. , Brun Bjerkås Ane , Bakke Jostein , Linge Henriette , D`Andrea William , van der Bilt Willem , Røthe Torgeir , Balascio Nicholas L. , Bradley Raymond S. , Grant Oliver , Fabel Derek , Xu Sheng
Published: March 2020

The Arctic is warming twice as fast as the global average, and the melting of mountain glaciers and ice caps has accelerated over the last two decades accompanied by reduced sea ice in the Arctic Ocean. Here we combine sedimentological and geochemical approaches to reconstruct changes in glacier extent at the marine terminating glacier Kongsbreen in order to put present-day climate changes into a longer time perspective. Glaciers are highly sensitive climate indicators as they rapidly respond to variations in summer temperature and precipitation, two parameters that are closely linked to atmospheric dynamics. This climate response is recorded by variations in glacier extent and moraine formation and by variations in glacial erosion and hence sedimentation rates in distal glacier-fed lakes. Lake Sarsvatnet is a threshold-lake that only receive glacial derived sediments when the surface of Kongsbreen crosses a local threshold. When the catchment is ice-free, lake sedimentation rate is lower and dominated by material weathered from the immediate proximity and organic-rich sediments. Based on seismic surveying seven coring sites were selected in three different sub-basins in lake Sarsvatnet. Laboratory analyses, including geochemical measurement by XRF scanning and XRD, CT scanning, grain size and measurements of magnetic proxies, were preformed in order to fingerprint the inorganic sediments. Chronological control is based on radiometric dating (14C, 210Pb, and 10Be). Erratics (n=3, 125-306 m a.s.l.) indicate ice-free conditions since 13.0±1.1 ka (2σ), overlapping with the oldest organic material found in the lake which is 11 860±80 cal. yr BP. Until around 7400 cal. yr BP lake Sarsvatnet is dominated by organic sedimentation. From around 7400 – 6900 cal. yr BP there is evidence for glacial input into the lake indicating the expansion of Kongsbreen and corresponding to the decline in temperature after the HTM. In the following millennia, and entering the Neoglacial period, there is evidence for mulitiple (~20) decadal to centennial-scale periods of glacier expansion, the most recent dated to AD 1650 marking the onset of glacier build-up towards the LIA maximum. This indicate that the Kongsbreen glacier had short lived expansion periods reaching LIA-like extension already during the middle Holocene, as well as multiple times during the Neoglacial.

 

 
Using the portable luminescence reader to assess the historical lateral mobility of river channels: preliminary promising results
Authors: Schmitt Laurent , Jautzy Timothée , Brill Dominik , Rixhon Gilles
Published: March 2020

Timothée Jautzy1,2, Dominik Brill3, Laurent Schmitt1, Gilles Rixhon4

Obtaining robust chronological data on landforms and their related deposits together with constraining rates of earth surface processes have constantly represented a major challenge in Quaternary science. In the fluvial context, Optically Stimulated Luminescence (OSL) is particularly well-established but still faces several limitations. It notably requires expensive and time-consuming sample processing and measurement, frequently resulting in a poor spatial and stratigraphical distribution of sampling which may negatively impact the chronological information. To overcome this main limitation, a Portable OSL reader (POSL) has been recently developed (Sanderson & Murphy, 2010). It consists in directly capturing a luminescence signal (counts per seconds) on unprepared sediment samples. This technique is quick and affordable but, unlike conventional OSL, is not able to yield numerical age estimates.

This contribution explores POSL capacities to provide useful relative age information on alluvial sediments from the last centuries. We study and compare 42 samples collected from three alluvial profiles located in the floodplain of a gravelly-sandy mid-sized river: the Bruche (i.e. a sub-tributary of the Upper Rhine, France). POSL stimulations, including both blue and infra-red signals, are performed in combination with grain size analysis. We observe (i) an overall increase of signal intensity with increasing depth, (ii) a very good match between blue and IR signals and (iii) no systematic correlation between signal intensity and grain size. Whilst this last point must still be confirmed (i.e. signal intensity does not primarily depend on grain size), our preliminary results positively suggest that POSL is a promising tool to provide a relative chronology for very young alluvial sediments. Furthermore, it may also provide information on geomorphic processes. These results will be combined soon to numerical dating (OSL and 14C) and compared to outcomes of a planimetric analysis to thoroughly reconstruct the historical lateral mobility of the Bruche river.
The value of information for the management of deficit irrigation systems
Authors: Schuetze Niels , Mialyk Oleksandr
Published: March 2020

Due to climate change, extreme weather conditions such as droughts may have an increasing impact on the water demand and the productivity of irrigated agriculture. For the adaptation to changing climate conditions, the value of information about irrigation control strategies, future climate development, and soil conditions for the operation of deficit irrigation systems is evaluated. To treat climate and soil variability within one simulation-optimization framework for irrigation scheduling, we formulated a probabilistic framework that is based on Monte Carlo simulations. The framework can support decisions when full, deficit, and supplemental irrigation strategies are applied. For the analysis, the Deficit Irrigation Toolbox (DIT) is applied for locations in arid and semi-arid climates. It allows the analysis of the impact of information on (i) different scheduling methods (ii) different crop models, (iii) climate variability using recent and future climate scenarios, and (iv) soil variability. The provided results can serve as an easy-to-use support tool for decisions about the value of climate and soil data and/or a cost-benefit analysis of farm irrigation modernization on a local scale.
Correlation structure of economic losses due to floods across Europe
Authors: Zanardo Stefano , Smith Rebecca , Nicotina Ludovico , Assteerawatt Anongnart , Hilberts Arno
Published: March 2020

Large scale climatic patterns and river network topology have an important impact on the space-time structure of floods. For example, in a recent study we showed that the effect of the North Atlantic Oscillation (NAO) is visible in the structure of economic losses at the European scale. The analysis revealed that in Northern Europe the majority of historic winter floods occurred during a positive NAO state, whereas the majority of summer floods occurred during a negative state. Through the application of a state-of-the-art flood catastrophe model, we also observed that there exists a statistically significant relationship between economic flood losses and the NAO. In this study we further advance the analysis by exploring the correlation structure of flood losses in Europe during different seasons and for different NAO states.  Flood loss correlation is measured in terms of “loss synchrony scale” (LSC), a metric formalized for this study following the definition of “flood synchrony scale” in Berghuijs et al. (2019). For an individual event and an individual CRESTA region, the LSC is defined as the maximum radius around the CRESTA, within which at least half of the other CRESTA regions experience a loss due to the same event. We analyse the LSC across Europe, as produced by the loss model, and check   for consistency with the data-based flood synchrony scale in Berghujs et al. (2019). We further explore how the LSC changes between different seasons, and between NAO states. This analysis can help improve financial preparedness to catastrophic floods as a better understanding of the correlation structure of the flood events allows for a better distribution of resources as well as a more efficient application of mitigation measures.

Berghuijs W R, Allen S T, Harrigan S and Kirchner J W 2019 Growing spatial scales of synchronous river flooding in Europe Geophys. Res. Lett. 46 1423–8
Atmospheric circulation associated with the arrival of sargassum in the Caribbean Sea.
Authors: Salinas Jose Antonio , Maya María Eugenia , Hernández Constantina
Published: March 2020

The arrival of sargassum in a massive way generates adverse environmental, social and economic impacts. Little is known about its origin and trajectory, as well as the atmospheric and oceanic conditions under which it arrives at the Mexican coasts of the Caribbean. This poster presents a diagnosis of the seasonal, annual and interannual variability of atmospheric circulations in the Atlantic and Caribbean Sea, identifying the atmospheric conditions under which sargassum arrived on the Mexican coasts. 30 years of surface wind data from CFSR (Climate Forecast System Reanalysis) of NCAR on the Atlantic and Caribbean were analyzed, dividing the area into six areas, for each one its seasonal, annual and interannual variability was estimated, as well as its extreme values from 1989 to 2018, focusing the study on both the Caribbean Sea and the Atlantic coast of Brazil.

Once the mean, extreme winds (10th and 90th percentiles) and their correlation with the NAO (North Atlantic Oscillation) were diagnosed interannually, particular years of the recent period were analyzed: from 2010 to 2019 incorporating the wind convergence as a physical process associated with the accumulation of sargassum, surface pressure and sea surface temperature (SST) and also correlating it with the NAO index.

The results show that the atmospheric conditions for transporting sargassum along the Mexican coasts of the Caribbean are more favorable in summer than in winter, besides it, the higher extremes (90th percentile) in the Caribbean favor the transport of sargassum both in winter and in summer. However, "connectivity" with other regions (Central Atlantic) makes summer more favorable, but winter is potentially viable. The atmospheric conditions of recent extreme years are discussed: 2013 (without the arrival of sargassum), medium: 2015 and extreme 2018 (with abundant sargassum) for both summer and winter.
Short-term fate of atmospherically deposited nitrogen in temperate forest under warming
Authors: Duan Yihang , Fang Yunting
Published: March 2020

Anthropogenic activities have notably disturbed the natural carbon and nitrogen cycle since the industry revolution. The consequential results include a warmer climate and enhanced nitrogen deposition on forest ecosystems. Covering one-third of the landmass, forests possess vital ecosystem functions such as N retention and the resulting C sequestration. However, the ongoing changes in climate and nitrogen deposition could potentially alter these important processes. Therefore, measures need to be taken to assess the distribution of deposited N in warming forest ecosystems. Here, we use 15N tracer method to investigate the short-term (2 weeks, 1 month and 3 months) fate of deposited N in a temperate forest, and by taking advantage of the in situ infrared heating, we also attempt to explore the effect of warming ( 2 °C ) on deposited N in forest ecosystems. The results showed that deposited N was largely retained by litter in all treatments (38%-57%) and mineral soil layers contained the least nitrogen. Total 15N recovery of different ecosystem compartments between warmed and control treatments showed distinct pattern, recovery in warming treatment increased from 72% to 97% after 1 month while the respect recovery of control treatment gradually decreased with time. In the top mineral soil layer (0-10cm), control treatments had higher recovery than warming treatment, suggesting warming may hinder deposited N from forging downwards, however, higher δ15N value in top mineral soil layer suggesting enhanced microbial activities maybe in action. Little leaching loss of deposited N both in warm and control was observed. Difference in deposited N fate between warming and control could deepen our understanding of how global warming influence forest ecosystem processes, particularly the N cycle.

Key words: Soil warming; 15N tracer; N deposition; N retention and redistribution; Global warming; Temperate forest
Sentinel-1 for Granada coast landslides monitoring and potential damage assessment
Authors: Barra Anna , Reyes-Carmona Cristina , Monserrat Oriol , Glave Jorge Pedro , Herrera Gerardo , Mateos Rosa María , Sarro Roberto , Bejar Marta , Azañón José Miguel , Crosetto Michele
Published: March 2020

The InSAR technique has been proved to be a powerful tool in order to detect, monitoring and analyse movements related to geological phenomena. Its application ranges from regional/national scale to a very detailed scale, up to a single building analysis. Moreover, since 2014, the free and constant availability of Sentinel-1 data has been helping the tendency of using more and more this technique in the institutional risk management activities. Many European and national projects have been financed in order to investigate and improve the processing performances and broaden the operational use and application of the results. In this work, we present the first results developed in the framework of the project Riskcoast (SOE3/P4/E0868) over an area of around 4 km2 in Andalucía (Spain), including the city and the coast of Granada. Riskcoast has been funded by the Interreg Sudoe Programme through the European Regional Development Fund (ERDF). The presented work is as an example of multi scale (medium to large) application of InSAR for geohazard applications. The velocity map including the estimation of the displacement time series have been produced over the whole area by processing 139 radar images of the Sentinel-1 (A and B). Starting from those results a rapid and semi-automatic extraction of the most significant active displacement areas (ADA) has been performed. Then, after a classification of the detected areas, a more detailed analysis has been done over some selected costal landslides. Over those landslides a damage mapping has been generated based on field surveys, and then analysed together with the spatial gradient of displacement derived by the InSAR results. The Riskcoast project will be introduced and the first results presented.
Leader discharge stepping in dry and humid air
Authors: Malagón-Romero Alejandro , Luque Alejandro
Published: March 2020

Long spark discharges of about one meter and natural lightning show a polarity asymmetry.  While positive discharges propagate continuously, negative discharges propagate in a stepped manner. This stepped propagation is mediated by the so-called space stem, an isolated region in the streamer corona of depleted electron density and enhanced electric field. Kostinskiy et al. 2018 [1] reported the stepping of positive leaders under high humidity conditions and Malagón-Romero et al. 2019 [2] showed that positive leader steps, if they exist, would be shorter and thus harder to observe in experiments. 

In this work we present the results of our simulations for the evolution of a space stem precursor [2] under dry and humid air conditions. These results show that the presence of water molecules enhances the electric field and the heating rate of the space stem, reaching 2000 K considerably faster than in dry air. This could make feasible the stepping of positive leader discharges under high humidity conditions as observed by Kostinskiy et al. 2018 [1].

 

[1] Kostinskiy, A. Y., Syssoev, V. S., Bogatov, N. A., Mareev, E. A., Andreev, M. G., Bulatov, M. U., & Rakov, V. A. (2018). Abrupt elongation (stepping) of negative and positive leaders culminating in an intense corona streamer burst: Observations in long sparks and implications for lightning. Journal of Geophysical Research: Atmospheres, 123, 5360–5375.

[2] Malagón-Romero, A., & Luque, A. (2019). Spontaneous emergence of space stems ahead of negative leaders in lightning and long sparks. Geophysical Research Letters, 46, 4029–4038. https://doi.org/10.1029/ 2019GL082063
The role of Evapotranspiration and Water Use Efficiency in Agriculture in Portugal
Authors: Vaz José , Gouveia Célia M. , Trigo Isabel F.
Published: March 2020

Understanding climate variability and change and its impacts on natural systems is becoming more and more important as changes in earth surface condition near surface air temperature and precipitation. Over Portugal, the observed warming trends have been found to be asymmetric with respect to seasonal and diurnal cycles, with greatest warming occurring for the minimum temperature and during winter and spring. These observed trends exert strong influences on agriculture systems, affecting production viability through changes in winter hardening, frost occurrence, growing season lengths and heat accumulation for ripening potential.

Remote sensing technology has been developing steadily and its products can provide many applications in agriculture, namely crop identification, crop growth monitoring and yield prediction. Recently the LSA SAF team set up a strategy to generate long term data records from Meteosat Second Generation satellite series (2004 to present), releasing Land Surface Temperature (LST), Reference Evapotranspiration (ETREF) and Vegetation parameters (FAPAR, LAI and FVC) using a stable set of input data and algorithm, which would be suitable for climate variability and change detection studies. On the other hand, a new product to characterize the ecosystem processes, the Gross Primary Production (GPP), is under production since 2018.

In this work we propose to computed Water Use Efficiency (WUE), as the ratio between Gross Primary Production (GPP) and Reference Evapotranspiration (ETREF), using LSA-SAF Products. WUE translates the exchanges of carbon and water gross fluxes, between natural ecosystem and the atmosphere, allowing to monitor the adaptability of the ecosystems to climate change. The role played by Evapotranspiration and Water Use Efficiency for different crops in Portugal is evaluated, namely on Wine Production for Douro Region. Results for 2018 and 2019 highlights the vulnerability of the different sectors of Douro Region to dry and wet conditions, namely helping to analyze the impact of droughts on Douro wine production.

Acknowledgements: This study was performed within the framework of the LSA-SAF, co-funded by EUMETSAT This work was partially supported by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under projects CLMALERT (ERA4CS/0005/2016).
Landslide Early Warning with Rainfall Data from Correcting Weather Radar Reflectivity Using Machine Learning
Authors: Li Pei-Chen , Yu Teng-To
Published: March 2020

Taiwan is located at the northwest side of Pacific Ocean and also in the Circum-Pacific Seismic Belt, as a result, suffers from frequently typhoons and earthquakes. The plate collision creates steep mountains account for 70% area of Taiwan. Averaged annual rainfall is 3600 mm in Taiwan, whenever typhoon or weather front brings heavy rainfall addition with geological instability thus increase the landslide occurrence. Rainfall gauge stations are sparse in the mountainous region, and the interpolated rainfall are usually underestimated. The error sources include 1.) variation of raindrop size distribution which is rarely known and varies in time and space (James, 1979); 2.) radar beam attenuation, the rainfall estimation will be underestimated as distance from radar to gauges increase ( Joss, 1998); 3.) beam blockage by mountains, when the beam encounters terrain blocking, it will cause signal interference, which is known as ground clutter (Li and Chen, 2002). Therefore, it is necessary to overcome those issues while try to predict accurate rainfall via radar reflectivity in the mountain regions.

In this research, we use radar reflectivity combines ground rainfall gauges to compensate the forecasting rainfall. The first method uses the known radar echo intensity (Z) and the rainfall of ground stations (R) to calculate the A and b coefficients by genetic algorithm with the exponential relationship, Z=A*Rb, proposed by Marshall and Palmer. However, the results are unreasonable, the value of A is varying in 0.01-1000, mostly under 1, and the value of b is varying in 0.1-30. Hence, we decide to use another method. First, we assume that for a short distance (ex: 30 Km), the raindrop size correction factor is constant without attenuation and beam blockage. Second, we estimate the correction factor with the attenuation pattern with distance. Third, the beam blockage from mountains is then considered, and it also takes the first two corrections in consideration. The approach we used is artificial neural network (ANN) to compensate the estimated rainfall from real time radar reflectivity.

The purpose of this study is to estimate the accurate rainfall of potential landslide area hours ahead typhoon or weather front reaches, we use the historical route of radar echo to infer the path of movement of next hour. If the estimated rainfall exceeds landslide thresholds, the alarm system will be activated. With these efforts the estimated rainfall in the mountain region is improved 70% from tryout experiments. It is found that is correction for radar reflectivity is not an universal transformation, it is depended on the nature of water concentration and also the drop size within the weather front.

 

Key words: Radar Echo, Artificial Neural Network, Early Warning
Plastic waste input from Guadalquivir River to the ocean
Authors: Quintana Sepúlveda Rocio , González Fernández Daniel , Cózar Cabañas Andrés , Vilas Fernández Cesar , González Ortegón Enrique , Baldo Martínez Francisco , Morales Caselles Carmen
Published: March 2020

Around 8 million tons of plastic waste are leaked from land into the ocean annually. One of the main pathways of plastic input into the ocean is rivers, but there is no comprehensive information about the amount and nature of litter transported. This study presents results of a monthly monitoring over a two years period in the estuary of Guadalquivir River, southern Spain. The samples, which consisted of passive hauls, were taken from a traditional glass eel fishing boat anchored with three nets working in parallel. The nets, with a mesh of 1 mm and an opening of 2.5 (width) × 3 (depth) metres, filtered around 60,000 m3 per sample. Our methodological approach allowed characterization of virtually all plastic sizes in river waters, comprising micro-, meso- and macroplastics. Plastic items were dominated by pieces of film (70% in number). Microplastics in the size interval from 2.5 to 4.0 mm represented half of the total identified items. Small fragments in Guadalquivir River comprised most of the plastic mass input to the sea. Our results support the relevance of fragmentation processes inland, and the role of rivers and estuaries as sources of microplastics to the ocean.
Regional scale prospectivity modelling of NW India for REE deposits associated with carbonatites and alkaline complexes
Authors: Aranha Malcolm , Porwal Alok , Sundaralingam Manikandan , Markan Amber , González-Álvarez Ignacio , Rao Karunakar
Published: March 2020

The rare earth elements (REEs) are a group of seventeen metals including 15 lanthanides, scandium and yttrium.  These metals have been projected to be critical for future industrial development. However, India currently does not have any economic grade primary deposit of REEs; all of India’s production comes from monazite-bearing beach sands along the eastern and western coasts that have been derived from REEs-enriched continental rocks such as pegmatites or carbonatites. This contribution documents a GIS-based prospectivity model for exploration targeting of REE associated with carbonatites and alkaline-complexes in the geologically permissive tracts of NW India comprising parts of western Rajasthan and northern Gujarat. A mineral systems approach is applied to model the key ingredients of an REE system including geodynamic setting; fertile mantle/crustal sources of REEs; deep to shallow crustal architecture; and REE deposition.  This conceptual genetic model of REE mineral systems is, in turn, used to identify the key regional-scale REE-deposit targeting criteria in NW India. Regional-scale multi-parametric exploration datasets are processed to represent the targeting criteria in form of predictor GIS layers. Finally, an expert-driven fuzzy inference system is designed for delineating and raking prospective REE targets. Simultaneously, the stochastic and systemic uncertainties in the prospectivity modeling are modelled to delineated (a) high priority REE exploration targets areas with low uncertainty and high prospectivity for immediate ground follow up and (b) areas with high uncertainty and high prospectivity for further data acquisition in order to reduce uncertainty.
Shotgun DNA, pollen and biological multi-proxy analysis of Lateglacial lake sediments from Monticchio, Italy
Authors: Parducci Laura , Nota Kevin , Tinner Willy , van Leeuwen Jacqueline , van der Knaap Pim , Sachse Dirk , Liang Zuobing , Brauer Achim , Schwab Markus J. , Zhao Xuery , Marchetto Aldo , Lami Andrea , Wulf Sabine
Published: March 2020

We used shotgun DNA sequencing of the full metagenome preserved in varved lake sediments from southern Italy (Lago Grande di Monticchio) to investigate the whole diversity of taxonomic groups present. We combine sedimentary aDNA and pollen data as well as other biological multi-proxy data and tested if it was possible to correlate the relative abundances of plants and other biological communities to distinct climatic shifts that occurred between the Late Glacial and Holocene. In addition, we used the metabarcoding technique to compare the two sequencing approaches specifically for plants.

Our studies showed that the inhibition of DNA replication was almost absent in older (full glacial) sediment samples while it increased substantially in more recent samples. DNA provides a strong signal of plant community changes and a large number of new plant taxa were recorded. A comparison between sequencing approaches and proxies highlights differences and similarities and supports earlier findings that plants growing close to or within a lake are often recorded by DNA and that DNA provides important complementary information to that collected from palaeoecological analyses. Nevertheless, increasing DNA reference libraries and enrichment strategies prior to sequencing are necessary to improve the potential and accuracy of plant identification using the metagenomic approach.