bluuebunny/crossref_metadata_2025 huggingface dataset:
Climatic drivers and biogeophysical feedbacks: a causal inference approach over multiple temporal scales
Authors: Claessen Jeroen , Molini Annalisa , Martens Brecht , Detto Matteo , Demuzere Matthias , Miralles Diego G.
Published: March 2020

Earth system models (ESMs) need to correctly simulate the impact of climate on vegetation, as well as the feedback of vegetation on climate. Improving the skill of ESMs in representing climate—biosphere interactions is crucial to enhance predictions of climate and ecosystem functioning. Correlation and regression techniques are commonly used to study these interactions statistically, but these methods lack the ability to unravel the bidirectional nature of the climate–biosphere system. Here, we explore these interactions across multiple temporal scales by adopting a spectral Granger causality framework that allows identifying potentially inter-dependent variables. Multi-decadal remotely-sensed records are used to analyse the impact of key climatic drivers (precipitation, radiation and temperature) on vegetation (Leaf Area Index, LAI), as well as the biophysical feedback on local climate. These observational results are in turn used to benchmark a set of Coupled Model Intercomparison Project Phase 5 (CMIP5) members at the global scale.

Results show that the climate control on LAI variability increases with longer temporal scales, being the highest at inter-annual scales. Globally, precipitation is the most dominant driver of vegetation at monthly scales, particularly in (semi-)arid regions, as expected. The seasonal LAI variability in energy-driven latitudes is mainly controlled by radiation, while air temperature controls vegetation growth and decay in northern latitudes at inter-annual scales. ESMs have a tendency to over-represent the climate control on LAI dynamics, and especially the role of precipitation at inter-annual scales. Likewise, the widespread effect of LAI variability on radiation, as observed over the northern latitudes due to albedo changes, is also overestimated by the CMIP5 models. Overall, our experiments emphasise the potential of benchmarking the representation of climate—biosphere interactions in online ESMs using causal statistics in combination with observational data.
Comparison and characterization of the field Atomic Quantum Gravimeter (AQG#B01)
Authors: Champollion Cédric , Cooke Anne-Karin , Le Moigne Nicolas
Published: March 2020

The recent advancements in gravity quantum sensors promise maintenance-free, easy to use, continuous and accurate monitoring devices. This technological breakthrough in gravity instrumentation offers new possibilities for both laboratory and field experiments in different geosciences applications. These new gravity quantum sensors allow e.g. for the monitoring of transient processes in volcanology, plate tectonics (slow slip events) or hydro-geology (pumping tests).

The first commercial field quantum gravimeters are nowadays available (AQGB, Muquans TM). The AQG#B01 is actually under validation. It is tested and compared with a superconducting gravimeter (GWR iGrav#002 and an absolute ballistic gravimeter (MG-L FG5#228) in the French Larzac Observatory () during more than 1 month. A first small (50 nm/s²) transient gravity variation caused by hydro-geological charge has been recorded by both the quantum and superconducting gravimeter.

Additionally its sensitivity to environmental noise is characterized by its Allan variance. Absolute ballistic comparison during one month allows to estimate a maximum potential drift. Sensitivity tests on instrument tilts and orientation have been done. In order to evaluate the AQG-B as a field sensor, sensitivity to external temperature changes have been tested in the range 10°C-30°C. All the tests allow a clear characterization of the AQG-B for future field experimentation.

AQG#B01 development has been funded is the frame of the grant “investissement d’avenir” EquipEx RESIF-CORE.
Early European Observations of Precipitation Partitioning by Vegetation: A Synthesis and Evaluation of 19th Century Findings
Authors: Friesen Jan , Van Stan II John T.
Published: March 2020

The first contact between precipitation and the land surface is often a plant canopy. The resulting precipitation partitioning by vegetation returns water back to the atmosphere (evaporation of intercepted precipitation) and redistributes water to the subcanopy surface as a “drip” flux (throughfall) and water that drains down plant stems (stemflow). Prior to the first benchmark publication of the field by Horton in 1919, European observatories and experimental stations had been observing precipitation partitioning since the mid-19th century. In this paper, we describe these early monitoring networks and studies of precipitation partitioning and show the impressive level of detail. Next to a description of the early studies, results included in this synthesis have been digitized and analyzed to compare them to recent studies. Although many early studies lack modern statistical analyses and monitoring tools that have become standard today, they had many strengths (not necessarily shared by every study, of course), including: A rigorous level of detail regarding stand characteristics (which is often lacking in modern ecohydrological studies); high-resolution spatiotemporal throughfall experiments; and chronosequential data collection and analysis. Moreover, these early studies reveal the roots of interest in precipitation partitioning processes and represent a generally forgotten piece of history shared by the hydrology, meteorology, forestry, and agricultural scientific communities. These studies are therefore relevant today and we hope modern scientists interested in plant-precipitation interactions will find new inspiration in our synthesis and evaluation of this literature.
Post-orogenic sediment drape and flux of mountain range-foreland basin systems: An example from the Northern Pyrenees
Authors: Bernard Thomas , Sinclair Hugh , Naylor Mark , Weir Elliot , Christophoul Frédéric , Ford Mary
Published: March 2020

The transition from syn- to post-orogenesis is generally identified in foreland basins by a switch from active subsidence and deposition to isostatic rebound and erosion. However, the nature of the interplay between isostatic rebound and sediment supply, and their impact on the topographic evolution of a range and foreland basin during this transition has not been fully explored.

Here, we use a box model to explore the syn- to post-orogenic evolution of foreland basin/thrust wedge systems. Using a set of parameter values that approximate the northern Pyrenees and the neighbouring Aquitaine foreland basin, we evaluate the controls on: 1) the sediment drape over the frontal parts of the retro-wedge and 2) the sediment accumulation into surrounding continental margins following cessation of crustal thickening. Conglomerate and sandstone sediments preserved at approximately 600 m elevation, which is ~300 m above the present mountain front in the northern Pyrenees record an age of ca. 12 Ma, approximately 8 Myrs younger than the last evidence of crustal thickening in the wedge. These sediments formed a regional drape that reached up to approximately 800 m elevation, but are now preserved in low gradient patches, and are associated with more regional surfaces across the northern Pyrenees. Using the model, this post-orogenic sediment drape can be explained by the combination of a sustained, high sediment influx from the range into the basin relative to the efflux out of the basin, combined with cessation of basin subsidence. The model also predicts higher sediment flux out of the system during the post-orogenic phase involving an increase of sediment accumulation as observed in the Bay of Biscay during this interval.

Post-orogenic sediment drape and increased sediment flux out the mountain range-foreland basin system are proposed as generic processes of these systems.
Remote Sensing of Large River Basins
Authors: Uereyen Soner , Bachofer Felix , Huth Juliane , Klein Igor , Kuenzer Claudia
Published: March 2020

Irrespective of administrative boundaries, river basins are natural spatial units covering the entire land area. They provide many resources, including freshwater, which is essential for the environment and human society, as well as irrigation water and hydropower. At the same time, river basins are highly pressured i.e. by human induced environmental changes, such as deforestation, urban expansion, dam construction, as well as climate change induced sea level rise at estuarine regions and extreme events such as droughts and flooding. Therefore, monitoring of river basins is of high importance to understand their current and future state, in particular for researchers, stake holders and decision makers. However, land surface and surface water variables of many large river basins remain mostly unmonitored at basin scale. Currently, only a few inventories characterizing large scale river basins exist. Here, spatially and temporally consistent databases describing the evolution and status of large river basins are lacking. In this context, Earth observation (EO) is a potential source of spatial information providing large scale data at global scale. In this study, we provide a comprehensive overview of research articles focusing on EO-based characterization of large river basins and corresponding land surface and surface water parameters, we summarize the spatial distribution and spatial scale of investigated study areas, we analyze used sensor types and their temporal resolution, and we identify how EO can further contribute to characterization of large river basins. The results reveal that most of the reviewed research articles focus on mapping of vegetation, surface water, as well as land cover and land use properties. In addition, we found that research articles related to EO applications hardly investigate study areas at the spatial scale of large river basins. Overall, the findings of our review contribute to a better understanding of the potentials and limitations of EO-based analyses of large river basins.
Recent ground thermal dynamics and variations in northern Eurasia
Authors: Chen Liangzhi , Aalto Juha , Luoto Miska
Published: March 2020

Ground thermal regime in cold environments is key to understanding the effects of climate change on surface–atmosphere feedbacks. The northern Eurasia, covering over half of terrestrial areas north of 40°N, is sensitive to the ongoing climate change due to underlain permafrost and seasonal frost. Here, we quantify the recent ground thermal dynamics and variations over northern Eurasia by compiling measurements of soil temperature data over 457 sites at multiple depths from 1975-2016. Our analysis shows that the mean annual ground temperature has significant warming trends by 0.30–0.31 °C/decade at depths of 0.8, 1.6, and 3.2 m. We found that the changes in annual maximum ground temperatures were more pronounced than mean annual ground temperatures with a weakened warming magnitude (0.40 to 0.31°C/decade) from upper to lower ground. Our results also suggest the substantial differences in warming magnitudes through parameters and depths over different frost-related areas. The ground over continuous permafrost area warmed faster than non-continuous permafrost and seasonal frost areas in shallow ground (0.8 and 1.6 m depth) but slower in deeper ground (3.2 m). Our study highlights the varied ground temperature evolutions at multiple depths and different frost-related ground, suggesting the importance of separated discussions on different frost-affected ground in application and future research. Noteworthy, the results indicate that the significant ground warming can promote greenhouse gas emissions from soil to atmosphere, further accelerating climate change.
Drifting away from reality : A cheap way to get lagrangian measurements
Authors: Chevalier Cristèle , Koenig Guillaume
Published: March 2020

Beauty may sometimes lie in the eyes of the beholder, but in science it always lies in simplicity. We tested a very simple concept to get drifting platforms  that we could track and equip with sensors. We equipped an available floating device with a commercial GPS tracking system.  We tested this in several campaigns ( Italia, New-Caledonia, Tunisia and Guadeloupe) to study surface drifts. Later, we added chemical sensors to collect of lagrangian measurements. Here we present  the general setting of the drifter and the results of the first tests, which proved its efficiency and robustness despite its cheapness and its simplicity to use. We also discuss possibility of adding various kinds of sensors.
The penetration of Labrador Slope Water to Cape Hatteras and its role in Gulf Stream Dynamics
Authors: New Adrian , Smeed David , Blaker Adam , Mecking Jenny
Published: March 2020

Labrador Slope Water is known to exist in the Slope Sea off the US eastern shelf as a relatively fresh and cool water mass deriving from the Labrador Current further north, and is present between the upper layer US shelf-derived water masses and the deeper Deep Western Boundary current waters, typically near 400-600m. This LSLW  is investigated in the EN4 database and shown to penetrate as far south as Cape Hatteras (74-75°W), having previously only been described as far west as the Gulf of Maine (66°W). We then examine, using both EN4 and Line W observations, the changes of this water mass between 2005-2008, when the strength of Atlantic Meridional Overturning Circulation (AMOC) measured by the RAPID array at 26°N, was high, and 2009-2015, when the AMOC was low. We show that in the AMOC high period, there was a larger volume of the LSSW present on the northern side of the Gulf Stream system which resulted in an increased meridional slope of the isopycnals near these depths, commensurate with increased geostrophic transport, and also in a more southerly position, of the Gulf Stream after separation at Cape Hatteras. The LSLW could therefore play an important role in decadal timescale variations in the North Atlantic climate system through its impact on the Gulf Stream and AMOC.
Optimal water quality monitoring network during road construction using Bayes and Entropy theories
Authors: Ghorbani Mooselu Mehrdad , Liltved Helge , Nikoo Mohammad Reza , Hindar Atle , Meland Sondre
Published: March 2020

The spatial variation of road construction runoff, and environmental impacts on both the terrestrial and aquatic environment necessitate the monitoring of receiving water quality. The paper proposed an integrated methodology for spatial optimization of the water quality monitoring network (WQMN) using information-theoretic techniques, including the concepts of the Transinformation entropy (TE) and the value of information (VOI). First, based on the correlation analysis, the most significant water quality parameters were selected. Then, using the Canadian Council of Ministers of the Environment (CCME) method, the water quality index (WQI) was computed in each potential monitoring station. After that, the VOI and TE for all potential stations were calculated. To achieve an optimal network among potential stations, the NSGA-II multi-objective optimization model was developed considering three objective functions, including i) minimizing the number of stations, ii) maximizing the VOI in the selected network, and iii) minimizing TE by the selected nodes. The optimization model resulted in a set of optimal solutions for WQMNs, called Pareto-front. Finally, two multi-criteria decision-making models including TOPSIS and PROMETHEE were utilized for choosing the best solution on the Pareto-front space considering various weighing scenarios assigned to objectives. The applicability of the presented methodology was assessed in a WQMN of a road construction site (33 km) in E18 highway, south of Norway. The selected solutions by TOPSIS and PROMETHEE models present the WQMN with maximum VOI and minimum TE among 33, and 28 potential stations, respectively.
Evaluation of 2018 drought and effectiveness of adaptation measures in the Netherlands
Authors: van Huijgevoort Marjolein H.J. , de Wit Janine A. , Bartholomeus Ruud P.
Published: March 2020

Extreme dry conditions occurred over the summer of 2018 in the Netherlands. This severe drought event led to very low groundwater  and surface water levels. These impacted several sectors like navigation, agriculture, nature and drinking water supply. Especially in the Pleistocene uplands of the Netherlands, the low groundwater levels had a large impact on crop yields and biodiversity in nature areas. Projections show that droughts with this severity will occur more often in the future due to changes in climate. To mitigate the impact of these drought events, water management needs to be altered.

In this study, we evaluated the 2018 drought event in the sandy regions of the Netherlands and studied which measures could be most effective to mitigate drought impact. We have included meteorological, soil moisture and hydrological drought and the propagation of the drought through these types. Droughts were determined with standardized indices (e.g. Standardized Precipitation Index) and the variable threshold level method. Investigated measures were, for example, higher water levels in ditches, reduced irrigation from groundwater, and increased water conservation in winter. We also studied the timing of these measures to determine the potential for mitigating effects during a drought versus the effectiveness of long term adaptation. The measures were simulated with the agro-hydrological Soil–Water–Atmosphere–Plant (SWAP) model for several areas across the Netherlands for both agricultural fields and nature sites.

As expected, decreasing irrigation from groundwater reduced the severity of the hydrological drought in the region. Severity of the soil moisture drought also decreased in fields that were never irrigated due to the effects of capillary rise from the groundwater, but, as expected, increased in currently irrigated fields. Increasing the level of a weir in ditches had a relatively small effect on the hydrological drought, provided water was available to sustain higher water levels. This measure is, therefore, better suited as a long term change than as ad hoc measure during a drought. The effectiveness of the measures depended on the characteristics of the regions; for some regions small changes led to increases in groundwater levels for several months, whereas in other regions effects were lost after a few weeks. This study gives insight into the most effective measures to mitigate drought impacts in low-lying sandy regions like the Netherlands.
Timing of crustal melting and magma emplacement at different depths: insights from the Permian in the Western Alps
Authors: Manzotti Paola , Bégué Florence , Kunz Barbara , Rubatto Daniela , Ulianov Alexey
Published: March 2020

The pre-Alpine basement of the Adriatic plate in the Southern Alps exposes an exceptionally complete section across the continental crust (Ivrea Verbano: lower crust; Serie dei Laghi: upper crust). The section was weakly reworked during Jurassic extension and Cretaceous to Miocene Alpine shortening. The Insubric Line, an Alpine crustal-scale south-vergent backthrust, separates the Southern Alps from the Alpine nappe stack. The pre-Alpine basement of the Adriatic palaeomargin is intensely reworked in this stack, and is now part of the Sesia-Dent Blanche nappes (Manzotti et al. 2014) and other, smaller, Adria-derived units (e.g. Emilius).

The less deformed part of the Sesia-Dent Blanche nappes are the IIDK and Valpelline Series. Based on lithological similarities, they have been correlated with the Ivrea-Verbano Zone (Carraro et al. 1970). This equivalence has been confirmed by subsequent studies, including detailed U-Pb zircon ages of metamorphic (Kunz et al., 2018) and magmatic events. The other units of the Sesia-Dent Blanche nappes (the Arolla Series, the Gneiss Minuti, and the Eclogitic Micaschists) have been pervasively reworked during the Alpine orogeny, from greenschist to eclogite-facies. Identification of the age and nature of their pre-Alpine protoliths, and of the grade and age of their pre-Alpine metamorphism heavily relies on field and petrological data on key outcrops, supported by U-Pb dating.

If the IIDK and Valpelline Series represent the lower Adriatic crust, the other units may derive from the upper Adriatic crust, i.e. may be similar to the Serie dei Laghi in the Southern Alps. Alternatively, they may also represent pieces of the Adriatic lower crust that were pervasively re-hydrated during the Jurassic extension and/or the Alpine subduction (Engi et al., 2018), thus allowing re-equilibration at HP conditions during Alpine deformation.

This contribution will summarize a range of field, petrological, and geochronological data (obtained by LA-ICP MS on zircon, combined with in situ-oxygen isotope data measured by SIMS). This data set reveals significant differences in the timing of crustal melting, as well as magma emplacement at different depths. It can be concluded that the history of the Adriatic crust in the Alpine stack is comparable with that of the Southern Alps, with implications for the mechanical behaviour of the crust during the Alpine orogeny.

 

Manzotti et al. (2014). Swiss Journal of Geosciences, 107, 309-336

Carraro et al. (1970). Memorie della Società Geologica Italiana, 9, 19-224

Kunz et al. (2018). International Journal of Earth Sciences, 107, 203-229

Engi et al. (2018). Geochemistry, Geophysics, Geosystems, 19, 865-881
Multivariate data assimilation in a seamless sea ice prediction system based on AWI-CM
Authors: Mu Longjiang , Nerger Lars , Tang Qi , Losa Svetlana N. , Sidorenko Dmitry , Wang Qiang , Semmler Tido , Zampieri Lorenzo , Losch Martin , Goessling Helge F.
Published: March 2020

We implement multivariate data assimilation in a seamless sea ice prediction system based on the fully-coupled AWI Climate Model (AWI-CM, v1.1). AWI-CM has an ocean/ice component with unstructured-mesh discretization and smoothly varying spatial resolution, which aims for seamless sea ice prediction across a wide range of space and time scales. The assimilation uses a Local Error Subspace Transform Kalman Filter coded in the Parallel Data Assimilation Framework. To test the robustness of the assimilation system, a perfect-model experiment is configured to assimilate synthetic observations. Real observations from sea ice concentration, thickness, drift, and sea surface temperature are further assimilated in the system. The analysis results are evaluated against independent in-situ observations and reanalysis data. Further experiments that assimilate different combinations of variables are conducted to understand their individual impacts on the analysis step. Particularly we find that assimilating sea ice drift improves the sea ice thickness estimate in the Antarctic, and assimilating sea surface temperature is able to avert a circulation bias of the free-running model in the Arctic Ocean at mid-depth. We also test the performance of an extended experiment where the atmosphere is constrained by nudging toward reanalysis data. The second version of the system assimilating more observations also with a new atmospheric model is currently under development.
Combined effects of anthropogenic aerosols and global warming on the South Asian Monsoon
Authors: Dey Choudhury Ayantika , Raghavan Krishnan , Singh Manmeet , Panickal Swapna , Narayansetti Sandeep , A.Gopinathan Prajeesh , Vellore Ramesh
Published: March 2020

The South Asian monsoon (SAM) precipitation has been generally regarded to exhibit contrasting responses to greenhouse gas (GHG) and anthropogenic aerosol forcing, although it is not adequately clear as to how it might respond to the combined influence of GHG and aerosol forcing.  The present study examines the individual and combined effects of global warming and anthropogenic aerosols on the SAM based on a suite of numerical experiments conducted using the IITM Earth System Model version2 (IITM-ESMv2). Four sets of 50-year model integrations are performed using IITM-ESMv2 with different anthropogenic forcings 1) Pre-Industrial control, 2) anthropogenic aerosols of 2005 3) CO2 concentrations of 2005 4) anthropogenic aerosols and CO2 of 2005. In the experiment with the elevated CO2 level of 2005, an intensification of SAM precipitation and strengthening of large-scale monsoon cross-equatorial flow is noted relative to the PI-CTL run. In contrast, the experiment with elevated anthropogenic aerosols of 2005 shows a decrease of SAM precipitation and weakening of monsoon circulation relative to the PI-CTL run. A striking result emerging from this study is the strong suppression of SAM precipitation, pronounced weakening of the monsoon circulation and suppression of organized convection in response to the combined radiative effects of elevated CO2 and anthropogenic aerosols relative to the PI-CTL run. By diagnosing the model simulations it is noted that the radiative effects in the combined forcing experiment lead to a pronounced summer-time cooling of the NH as compared to the equatorial and southern oceans which are predominantly influenced by global warming, thereby creating a north-south differential radiative forcing over the Indian longitudes.  Additionally, the influence of absorbing aerosols over South and East Asia creates a surface radiation deficit over the region, stabilizes the lower troposphere, slows down the monsoon winds and reduces surface evaporation.  Although the anticyclones over the subtropical Indian Ocean intensify in the combined forcing experiment, the model simulation shows that much of the precipitation enhancement occurs to the south of the equator over the Indian Ocean whereas the moisture transport and convergence to the north of the equator is substantially reduced. Furthermore, the combined forcing experiment shows that anomalous large-scale descent over the subcontinent reinforces the suppression of organized convection giving rise to more intense breaks and weaker active spells in the southwest monsoon on sub-seasonal time-scales. This study hints that future decreases in NH aerosol emissions could potentially reverse the ongoing decreasing trend of the observed SAM precipitation since 1950s in a purely global warming environment.
Deformation history of the Marmara Granitoid and implications for a dextral shear zone in NW Anatolia
Authors: Bayrak Salim Birkan , Güraslan Işıl Nur , Ünal Alp , Kamacı Ömer , Altunkaynak Şafak , Yiğitbaş Erdinç
Published: March 2020

Marmara granitoid (47 Ma) is a representative example of the Eocene post-collisional magmatism which produced several granitic plutons in NW Anatolia, Turkey. It is a W-E trending sill-like magmatic body which was concordantly emplaced into the metamorphic basement rocks of Erdek Complex and Saraylar Marble. The granitoid is represented by deformed granodiorite which displays well-developed lineation and foliation in meso-scale defined by the elongation of mica and feldspar crystals and recrystallization of quartz however, in some places, magmatic textures are preserved. Deformed granodiorite is broadly cut by aplitic and pegmatitic dikes and contains mafic enclaves which display the same deformation indicators with the main granitoid.

Microstructural analysis shows that the solid-state deformation of the Marmara granitoid is classified as ductile deformation with high temperatures and ductile-to-brittle deformation with relatively lower temperatures. Evidence for the ductile deformation of the granitoid is represented by chessboard extinction of quartz, grain boundary migration (GBM) and subgrain rotation recrystallisation (SGR) which exhibits that the deformation temperature changed from 600 oC to 400oC. Bulging recrystallization (BLG), grain size reduction of amphibole, biotite and plagioclases and microcracks on plagioclases were considered as overlying ductile-to-brittle deformation signatures which develop between 300-<250 oC temperatures.

All of these field and micro-structural data collectively suggest that the shear sense indicators such as micafish structures and δ type mantled porphyroclasts displayed stair-steppings pointing out to a right lateral movement, indicating that the structural evolution and deformation history of Marmara granitoid was controlled by a dextral shear zone.
Wavenumber Decomposition and Extremes of Atmospheric Meridional Energy Transport in the Northern Hemisphere Midlatitudes
Authors: Lembo Valerio , Messori Gabriele , Graversen Rune , Lucarini Valerio
Published: March 2020

The atmospheric meridional energy transport in the Northern Hemisphere midlatitudes is mainly accomplished by planetary and synoptic waves. A decomposition into wave components highlights the strong seasonal dependence of the transport, with both the total transport and the contributions from planetary and synoptic waves peaking in winter. In both winter and summer months, poleward transport extremes primarily result from a constructive interference between planetary and synoptic motions. The contribution of the mean meridional circulation is close to climatology. Equatorward transport extremes feature a mean meridional equatorward transport in winter, while the planetary and synoptic modes mostly transport energy poleward. In summer, a systematic destructive interference occurs, with planetary modes mostly transporting energy equatorward and synoptic modes again poleward. This underscores that baroclinic conversion dominates regardless of season in the synoptic wave modes, whereas the planetary waves can be either free or forced, depending on the season.
Estimation of NOx, SO2 and HCHO emissions from the megacity of Lahore, Pakistan using car MAX-DOAS observations and comparison with regional model and TROPOMI satellite data
Authors: Razi Maria , Dörner Steffen , Kumar Vinod , Donner Sebastian , Ahmad Noor , Beirle Steffen , Khokhar Muhammad Fahim , Wagner Thomas
Published: March 2020

Lahore, megacity of Pakistan with more than 11 million inhabitants is a strong emission source of atmospheric pollutants. We present results of a top-down emission procedure for NOx and SO2 for Lahore, based on car multi-axis differential optical absorption spectroscopy (car-MAX-DOAS) observations. Additionally, the total flux of HCHO from the city is determined which can be seen as an indicator for VOC emissions. Results from two extensive campaigns, which took place in summer 2017 and spring 2018 will be presented. From the measured spectra, we retrieve the vertically integrated concentration (the so-called tropospheric vertical column density, VCD) of the trace gases along the driving route by using the so-called geometric approximation method. By combining these observations with ECMWF Re-Analysis wind data, the total fluxes of NOx, SO2 and HCHO from the city of Lahore are estimated. From both measurement campaigns, we also analyzed the seasonal variability of the above-mentioned species.

Derived NOx and SO2 emissions are compared to the bottom-up emission inventory EDGAR. Spatial disributions of the tropospheric NO2 and SO2 VCDs observed by car MAX-DOAS are compared with those simulated using a coupled regional-global model system (MECO(n)). We find that, the model is able to account for the spatial variablity but the VCDs are systematically underestimated by the regional model. Finally, derived NOx emissions are also compared to the emissions estimated from TROPOMI satellite observations.
Evaluation of energy balance closure correction methods for multiple eddy-covariance sites in different biomes
Authors: Mauder Matthias ,   Energy-balance closure correction evaluation team
Published: March 2020

The apparent lack of surface energy balance closure is one of the most crucial challenges in the measurement of biosphere-atmosphere exchange. In principle, this issue can have a variety of potential reasons, including instrumental errors and errors introduced in the data processing chain. In addition, secondary circulations have been identified as one of the main reasons for a non-closure of the surface energy balance, since the related energy transport cannot be captured by common eddy-covariance tower flux measurements. When present, neglecting this process will result in an underestimation of turbulent fluxes. Secondary circulations can, however, be represented by means of large-eddy simulations, which have been employed to develop a novel semi-empirical model to correct for the missing large-scale flux (De Roo et al. 2018, DOI 10.1371/journal.pone.0209022). In this study, we compare the results of this process-based method with two other previously published bulk-correction methods (Mauder et al. 2013, DOI 10.1016/j.agrformet.2012.09.006; Charuchittipan et al. 2014, DOI 10.1007/s10546-014-9922-6). These three correction methods are applied for multiple sites in different biomes around the world. Independent data of energy fluxes from these sites are used to assess which of these methods leads to the most reliable results, and we discuss the limitations of these corrections methods with respect to meteorological conditions and site characteristics, such as measurement height, the landscape-scale heterogeneity and terrain complexity.
Estimation of flood risk exposure with cross fertilization between multi-platform remote sensing and census information.
Authors: Boni Giorgio , Taramasso Angela Celeste , Roth Giorgio
Published: March 2020

Risk exposure adjournment in flood prone areas is usually limited by the unavailability of frequently updated information about urbanization and census. This limitation is produced mainly by the complexity of the long process that lead to thematic maps compliant with common product requirements.

Therefore, the mapping of exposed elements and population does not fully exploit the potential high refresh rate typical of remote sensing. This aspect may be particularly important in developing countries, where exposure may change at sub-yearly scale.

This work explores the potential of the combination of the high refresh rate of satellite night-time light products with the high precision of urban maps and census information. Target is the evaluation of the population exposure to the flood risk in urban areas.

The idea is to calibrate nightlight vs. urban density/population relations where contemporary estimations of both variables are available. These, combined with flood hazard maps, allows the estimation of the flood risk. Results will be validated using independent estimates of the population exposed to the flood risk in the same area.

Moreover, time series of nightlight products will be used to estimate the same variables at different times, demonstrating the possibility of rapid updates.

The work is based upon DMSP night-time light series, global urban footprint (GUF) maps by the German AeroSpace Center (DLR) and census data from the Italian institute of statistics (ISTAT). The independent data for the population exposed to risk are provided by the Italian Environmental Protection Agency (ISPRA).
Transition from geostrophic flows to inertia-gravity waves in the spectrum of a differentially heated rotating annulus experiment.
Authors: Rodda Costanza , Harlander Uwe
Published: March 2020

Inertia-gravity waves (IGWs) are known to play an essential role in the terrestrial atmospheric dynamics as they can lead to energy and momentum flux when they propagate upwards. An open question is to which extent nearly linear IGWs contribute to the total energy and to flattening of the energy spectrum observed at the mesoscale.
In this work, we present an experimental investigation of the energy distribution between the large-scale balanced flow and the small-scale imbalanced flow. Weakly nonlinear IGWs emitted from baroclinic jets are observed in the differentially heated rotating annulus experiment. Similar to the atmospheric spectra, the experimental kinetic energy spectra reveal the typical subdivision into two distinct regimes with slopes k-3 for the large scales and k-5/3 for smaller scales. By separating the spectra into a vortex and wave part, it emerges that at the largest scales in the mesoscale range the gravity waves observed in the experiment cause a flattening of the spectra and provide most of the energy. At smaller scales, our data analysis suggests a transition towards a turbulent regime with a forward energy cascade up to where dissipation by diffusive processes occurs.
Carbonyl sulfide and sun-induced fluorescence as joint constraints on terrestrial carbon cycling in a temperate alpine grassland ecosystem
Authors: Wohlfahrt Georg , Sakowska Karolina , Van der Tol Christiaan , Hammerle Albin , Spielmann Felix , Gerdel Katharina
Published: March 2020

Quantitative understanding and monitoring of gross primary productivity (GPP) and its response to environmental variables is critical for understanding the feedbacks of ecosystems to the changing climate and projecting the future climate state.

Due to limitations of the eddy covariance (EC) method related to the restricted spatial coverage obtained with the method, as well as drawbacks of the so-called CO2 flux partitioning approaches, adding scale-appropriate extra-information on canopy physiological status and flux partitioning is crucial for constraining gross photosynthesis (GPP), also beyond the ecosystem scale.

Here, we present the outcome of the H2020-MSCA-IF COSIF project aiming at investigating the potential of two novel GPP traces, i.e. carbonyl sulfide (COS) and sun-induced fluorescence (SIF) for inferring GPP.

The major result of the presented study are three independent GPP data sets obtained with different methods of contrasting theoretical backgrounds (CO2 flux partitioning, COS and SIF) in a temperate mountain grassland in Neustift, Austria (AT-Neu). Moreover, the study compares empirical approaches with a process-based estimates obtained using the “Soil-Canopy Observation Photosynthesis and Energy fluxes” (SCOPE) model, updated with a soil and leaf COS exchange module. The obtained results foster the use of repeated hyperspectral remote sensing observations together with radiative transfer and biochemical models for carbon assimilation monitoring.
Hydrogeochemical changes in trace element concentrations in connection with earthquakes and a volcanic eruption in Iceland
Authors: Franchini Stefania , Barberio Marino Domenico , Barbieri Maurizio , Billi Andrea , Boschetti Tiziano , Jónsson Sigurjón , Petitta Marco , Skelton Alasdair , Stockmann Gabrielle
Published: March 2020

The aim of this study was to identify changes of trace element concentration in groundwater and test for coupling with seismic and volcanic activity in Iceland. Samples used in this study were collected between September 2010 and June 2018 from the HA-01 groundwater well in Hafralækur (Northern Iceland), south of the Tjörnes Fracture Zone (oblique transform zone), and near the Laxá and Skálfandafljót river valleys. The temperature of the groundwater from the HA-01 well is 71–76 °C, pH is ca. 10.2 (at ~ 25ºC), and the dissolved solid content is about 240 ppm, which is typical of low temperature geothermal groundwaters in inland areas of Iceland. The HA-01 well groundwater is also influenced by mixing between old ice age aquifer and younger aquifer groundwater. The same samples were previously analyzed for major element concentrations and isotopic ratios, with results - changes prior to seismic activity - being published in recent papers. The 495 earthquakes (Mw≥4.0, September 2010 to June 2018) considered in this study are from the USGS database. Twenty-two of these earthquakes occurred in the Tjörnes Fracture Zone with Mw between 4.1 and 5.5 whereas the remaining ones with Mw between 4 and 5.5 were related to the Bárðarbunga eruption in central Iceland, which began on 29 August 2014 and ended on 27 February 2015. Results of trace element analysis highlight characteristic variations in the temporal series related to the Bárðarbunga eruption (onset in August 2014) and to the 2018 seismic swarm that occurred in the Tjörnes Fracture Zone. In particular, a marked increase of Li, B, Ga, Mo and Rb and a slight increase of Sr and V were observed prior to and in connection with the onset of the Bárðarbunga eruption. Moreover, our results show a pre-seismic (2018 seismic swarm in the Tjörnes Fracture Zone) hydrogeochemical variability greater than the background variability. Despite the distance to the Bárðarbunga eruption site, GPS data from northern Iceland show a clear strain changes that are associated with the large dike intrusion that fed the eruption and are possibly correlated with the hydrogeochemical time series. Results from this study in Iceland show that the hydrogeochemical monitoring of volcanic and seismic areas is a promising method in the science of seismic and volcanic precursors.
Beach-foredune ridges as proxies for climate-induced wave direction changes in South Atlantic during Late Holocene
Authors: Da Silva Ana Paula , Klein Antonio Henrique da Fontoura , Fetter Filho Antonio Fernando Harter , Hein Christopher , Mendez Fernando , Broggio Micael , Dalinghaus Charline
Published: March 2020

Variability in global wave climate has been observed to occur in response to climate changes influencing the wave-generating zones. This highlights the need for an improved understanding of long-term wave-climate cycles, considering the multi-decadal variability of the atmospheric patterns and large-scale climate drivers. In this study, a novel use of the morphology of former shorelines preserved in beach-foredune ridges was applied to reconstruct changes in predominant wave directions in the Subtropical South Atlantic during the Late Holocene. A 3km wide semi-continuous sequence of beach-foredune ridges preserved within the Pinheira Strandplain (Santa Catarina State, Brazil) was mapped in order to extract the orientation of the former shorelines and derive a 3000-year record of inferred mean wave direction. The mean wave direction series was compared to ~1000 years of decadal means of mid-latitude mean sea-level pressure gradients (âˆ†MSLP) and zonal westerly wind velocities estimated from the CESM1-CAM5 “Last Millennium Ensemble (LME)”, and to 2000 years of air-surface temperature anomalies for Southern Hemisphere. Results showed that multi-centennial cycles of oscillation in predominant wave direction occurred in accordance with stronger (weaker) South Atlantic mid-latitude mean sea-level pressure and zonal westerlies winds, favouring wave generation zones in higher (lower) latitudes and consequent southerly (easterly) wave climate dominance. It was identified the Southern Annular Mode as the main climate driver responsible for these changes, responding for 43% of the variance in the Subtropical South Atlantic atmospheric patterns in the last 1000 years. Long-term variations in interhemispheric air-surface temperature offsets, coincident with oscillations in wave direction, may have influenced wave-generation patterns similarly to the seasonal behaviour observed over recent decades. Periods of relatively warmer Southern Hemisphere (SH) as compared with Northern Hemisphere (NH) (e.g., during 400–800 CE and the Little Ice Age) favours the predominance of easterly wave energy flux along the eastern South American coast, whereas periods with equivalent NH-SH temperature anomalies (e.g., Medieval Warm Period) or with colder relative SH (last ~150 years) support an increase in the influence of the southerly wave energy flux over the South Atlantic. These results provide a novel geomorphic proxy for paleoenvironmental reconstructions and present new insights into the role of multi-decadal to multi-centennial climate variability on controlling coastal ocean wave climate.
Impact of global warming on the conditions of the Siberian rivers discharge formation
Authors: Vyazilova Anastasia , Genrikh Alekseev , Natalya Kharlanenkova , Natalya Glok
Published: March 2020

 The modern Arctic is becoming warmer and more humid, and the Arctic Ocean is increasingly free of ice in summer. One of the feedbacks of global warming in the arctic part of the climate system is an increase of downward long-wave radiation inflow to the surface of snow and ice due to an increase of the content of water vapor in the atmosphere of the Arctic. The source of the increase of the water vapor content in the arctic atmosphere is the atmospheric branch of the freshwater cycle, including moisture transport from low latitudes and inflow from the ocean surface. Moisture from low latitudes is transferred not only to the Arctic, but also to the adjacent continent of Eurasia, from where its excess is transferred by river flow to the Arctic Ocean. Strengthening of zonal transports of heat and moisture from oceanic regions to continents and meridional transports from low latitudes of the World Ocean to temperate and high latitudes is shown using the proposed indices of the zonal and meridional circulation. The indices were calculated according to the NCEP, ERA-Interim reanalysis data. It has been established that the increase in transports is manifested, in particular, in an increase of air temperature, in an increase of the total moisture content in the atmosphere over the area of Siberian rivers flow formation, in an increase of precipitation and, as a result, in an increase of the run-off of rivers flowing into the Arctic Ocean. The connection between the indices and surface air temperature, precipitation, atmospheric moisture content in the regions of catchment areas of three main Siberian rivers, Ob, Lena and Yenisei, confirmed the influence of atmospheric transports in the cold part of the year. Assessment of the relationship between changes of climatic conditions in the catchment areas and interannual changes of river runoff parameters indicated that annual runoff increases and mostly is affected by increase of average annual precipitation. The study was carried out with the support of the Russian Foundation for Basic Research (Project 18-05-60107).
MODIS images anda avalanche: operational use of satellite images in forecasting avalanche Hazard .
Authors: Valt Mauro , Salvatori Rosamaria , Salzano Roberto
Published: March 2020

The avalanche hazard is a critical task for the regional services in the Alpine region. For this reason, the characteristics of surface snow are continuously monitored in terms of micro-physics and metamorphism. The spatial distribution of the different types of snow covers (fresh snow, drift snow, melted snow, surface hoar, rain crusts, wet snow, dry snow) are used in the models aimed to forecast the avalanche hazard.

Satellite data are very important for routinely monitoring the snow cover and data provided by the Moderate Resolution Imaging Spectroradiometer (MODIS), onboard on the Terra and Aqua platforms, are an useful source of information for a modern avalanche assessment service.

More than one hundred MODIS images were processed, in the 2013-2020 period, for 2 areas located in the Dolomites, between Marmolada and Pale di San Martino groups (Veneto Region, Italy). The two training sites were used for the definition of a workflow useful for discriminating different types of snow surface. The defined workflow, based on the average radiometric values of bands 4, 5 and 6, were applied on the reflectances derived by the daily product MOD02HKM, with a spatial resolution of 500m. While band 4 and 5 (respectively visible radiation at 550nm and short-wave infrared at 1240nm) support the discrimination of different snow surfaces, the band 6 (short-wave infrared at 1630nm) is linked mainly to the presence of dry or wet snow on the surface.

The proposed workflow provided classification maps that were validated using observations recorded at the meteorological stations located in the test areas and by field surveys carried out by snow scientists. These results support the availability of a reliable tool based on remotely-sensed data, evidenced by the good agreement with field observations, which can be an optimal input for avalanche forecasting.