bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Quaternary deformation of the sub-Himalaya on 100 kyr timescales
Authors: Bouscary Chloé , King Georgina , Grujic Djordje , Lavé Jérôme , Hetényi György , Herman Frédéric
Published: March 2022

In mountain accretionary wedges, it is generally considered that the preservation of a topography in mechanical equilibrium is modulated by the activation of faults, sometimes internal to the prism, sometimes frontal. The folds of the Himalayan foothills correspond to the most frontal structures of the Himalayan prism. Understanding the timing of the initiation and the activity of these frontal folds can provide valuable information on the deformation sequences within the range (reactivation of the MCT, prograde sequences and transfer to frontal folds, ...) in response to tectonic and climatic forcing. Late Cenozoic climatic changes, including glaciations, might have impacted the denudation of the Himalayan range. The study of recent deformation rates is thus key for understanding lateral variations in deformation along the entire Himalayan arc, which will bring new constraints on the interactions between tectonics and surface processes at different scales time, as well as deepen our understanding of the seismic behaviour of the range.

 

Here we quantify exhumation rates in the Himalayan foothills using luminescence thermochronometry, which is a recently developed very-low temperature thermochronometer applicable between tens of years and a few hundred kyr. In contrast to classical methods, it can resolve thermal histories from the upper few km of the Earth’s crust, allowing spatial variations in exhumation rates across the Himalayas to be deciphered on sub-Quaternary timescales. An extensive data set of more than 40 Siwalik rock samples, from Western Nepal to Eastern Bhutan, was measured to complement other thermochronometric data and understand the sub-Quaternary deformation on the Himalayan foreland.

 

The results show along-strike variations in exhumation rates in the Himalayan foothills during the late Quaternary, with exhumation rates across the sub-Himalaya varying locally independently of precipitation trends and changes in the modern convergence rates. These along-strike variations may suggest that over the last 300 kyr, Himalayan shortening has not only been accommodated by the most frontal faults along the Himalayan range.
The Effects of COVID-19 Lockdown on Air Quality and Health in India and Finland
Authors: Sharma Shubham , Heibati Behzad , Suneja Jagriti , Kota Sri Harsha
Published: March 2022

The COVID-19 lockdowns worldwide provided a prospect to evaluate the impacts of restricted movements and emissions on air quality. In this study, we analyze the data obtained from the ground-based observation stations for six air pollutants (PM10, PM2.5, CO, NO2, O3 and SO2) and meteorological parameters from March 25th to May 31st in 22 cities representative of five regions of India and from March 16th to May 14th in 21 districts of Finland from 2017 to 2020. The NO2 concentrations dropped significantly during all phases apart from East India's exception during phase 1. O3 concentrations for all four phases in West India reduced significantly, with the highest during Phase 2 (~38%). The PM2.5 concentration nearly halved across India during all phases except South India, where a very marginal reduction (2%) was observed during Phase 4. SO2 (~31%) and CO (~41%) concentrations also reduced noticeably in South India and North India during all the phases. The air temperature rose by ~10% (average) during all the phases across India when compared to 2017-2019. In Finland, NO2 concentration reduced substantially in 2020. Apart from Phase 1, the concentrations of PM10 and PM2.5 reduced markedly in all the Phases across Finland. Also, O3 and SO2 concentrations stayed within the permissible limits in the study period for all four years but were highest in 2017 in Finland, while the sulfurous compounds (OSCs) levels increased during all the phases across Finland. The changes in the mobility patterns were also assessed and were observed to have reduced significantly during the lockdown. The benefits in the overall mortality due to the reduction in the concentrations of PM2.5 have also been estimated for India and Finland. Therefore, this research illustrates the effectiveness of lockdown and provides timely policy suggestions to the regulators to implement interventions to improve air quality.
Tuning the GRID MT method for the moment tensor inversion of small to moderate size earthquakes 
Authors: Menager Marine , Guilhem Trilla Aurélie , Delouis Bertrand
Published: March 2022

In order to rapidly detect, locate and characterize seismic events at regional scale, we are currently improving the parametrization of a continuous grid-search moment tensor inversion tool, called GRiD MT (Grid-based Real-Time Determination of Moment Tensor, Kawakatsu, 1998, Tsuruoka, 2009, Guilhem et al., 2011 and 2013, Menager et al., 2021). Here, we first design the procedure for small to moderate size earthquakes in south-eastern France, but we target its expansion to any potential regions of interest. This rapid and continuous moment tensor approach strongly depends on an adequate pre-selection of inversion parameters such as velocity models, station set, frequency band, grid spacing. In a proof of concept for France, we find source solutions (mechanism and magnitude) for two recent and moderate earthquakes (Mw 4.8 2019 Le Teil and M4.9 2014 Barcelonnette) very similar to those found by other institutes (CEA, GEOAZUR, USGS, INGV, …).

Moreover, instead of using a fixed time window in the inversion, we show that the quality of the solution can be improved by modifying each station’s time window depending on P and S wave travel times. This appears to be particularly true for small magnitude earthquake and potentially noisy data.

However, the previous selected parameters for Le Teil and Barcelonnette events are not the best ones to characterize the lower size events (3.4 < Mw < 4.0). We also propose an approach for automatically defining the best set of stations and frequency band depending on the targeted magnitudes in a region of interest. Based on signal/noise ratio (SNR) analysis to determine the signal quality for each station of a possibly dense seismic network, it helps the analyst in its GRiD MT parametrization. Moreover, here, azimuthal coverage is also taken into account in the station selection.

We illustrate the relevance of these proposed improvements with a selection of events. The ultimate aim is to facilitate the implementation of the GRiD MT method for other regions of interest and for different magnitude ranges. 
Tipping Points in the Amundsen Sea Sector, a comparison between 2D and 3D ice-sheet models
Authors: Mosbeux Cyrille , Gagliardini Olivier , Jourdain Nicolas , Urruty Benoit , Chekki Mondher , Gillet-Chaulet Fabien , Durand Gael
Published: March 2022

Ice mass loss from Antarctic Ice Sheet is increasing, accelerating its contribution to global sea level rise. Interactions between the ice shelves (the floating portions of the ice sheet that buttress the grounded ice) and the ocean are key processes in this mass loss. The most rapid recent observed mass loss from the Antarctic Ice Sheet is in the Amundsen Sea, where buttressing is declining as small ice shelves are being thinned rapidly by melting driven by inflows of warm Circumpolar Deep Water, leading to important grounding line retreats. Recent research indicates that ice sheets, especially the parts that rest on a bed below sea level such as most of the Amundsen sector, are particularly prone to an unstable and irreversible retreat that might lead to an important and fast global sea level rise.

As part of the European Horizon 2020 research project TiPACCs that assesses the possibility of near-future irreversible changes, so-called tipping points, in the Southern Ocean and the Antarctic Ice Sheet, we conduct numerical simulations perturbating the current conditions of the ice-ocean system in the Amundsen Sea Sector. More particularly, we use the Stokes flow formulation of the open-source ice flow model Elmer/Ice, forced with melt parametrization under the ice shelves to determine the effect of ocean warming on the ice-sheet evolution –eventually looking for the existence of future tipping points in the region. Since 3D-Stokes models can be numerically expensive, using the same Elmer/Ice framework (datasets, ocean and climate forcing), we compare our results to the more efficient but sometimes less accurate 2D-shallow–shelf(y)-Approximation (SSA). This methodology allows us to entangle the differences between the two models and better constrain the uncertainty linked to TiPACCs pan-Antarctic simulations based on the SSA.
The beautiful River Satsunai: Quantifying the effect of artificial flushing flows on channel planform morphology. 
Authors: Crabbe Ellie , Maniatis Georgios , Tsubaki Ryota
Published: March 2022

The introduction of river dams has resulted in a deleterious simplification of the geomorphological and hydrological characteristics within fluvial environments. To ensure riverine geomorphic diversity in dammed rivers, a variety of watercourse management techniques have been utilised. Flushing flows (the intermittent release of water and sediment from the dam reservoir) have been demonstrated to improve the longitudinal continuity of sediment flux, through the partial re-instatement of periodic flooding. Those flushes are designed to emulate hydrological disturbance events that correspond to natural flow regimes. However, few investigations have sought to characterise nor quantify the geomorphic impacts of flushing flows on channel planform morphology.

Prior to the operation of the Satsunaigawa Dam in 1998, the Satsunai River (Hokkaido, Japan) was renowned for its geomorphic diversity, featuring a plethora of braided channels with double-row bars. After the reported depletion of such features, flushing flows have been used as part of a wider management (2012-ongoing) towards improving the geomorphic diversity of the river.

To quantify the geomorphic impacts of the flushing flow on the planform morphology, a chronology of satellite images (between August 2014 and May 2020) were used to track the lateral mobility of the channel centreline across a 10.4 km reach of the river. Centreline lateral mobility tracking is then used as a proxy for the geomorphic response and differentiate between geomorphic change cause by: a) natural hydrological forcing and, b) artificial annual flushing flows as part of the restoration program.

Results from statistical tests of difference identified significant changes in centreline lateral mobility, both spatially and temporally, within the study reach. The intense natural hydrological forcing is also linked to statistically significant increase of the variability for the lateral mobility of the channel centreline.

Spatial comparisons indicate certain sub-reaches exhibiting high lateral mobility consistently in contrast to areas with statistically constant median values over the entire study period. In this context, the position of the sub-reaches in relation to the damn is formally tested as a predictor for the intensity of geomorphic change.

By contextualising the patterns of centreline lateral mobility within the wider hydrology of the Satsunai catchment, the geomorphic implications of the flushing flow can be critically assessed. This is the missing link between previous studies that focused either on the local study of hydraulic forcing or on the assessment of the ecological impact of the artificial flushing within the Satsunai catchment.
Spatial variability of organic matter in marine sediments from the Gulf of Cadiz
Authors: Ramírez-Cárdenas Teodoro , Liger Esperanza , Fernández-Salas Luís Miguel
Published: March 2022

This work analyses the spatial variability of organic matter (phytopigments, proteins and carbohydrates) in surface sediments from the Gulf of Cadiz (SW Iberian Peninsula). Sediment samples were taken in summer 2019 during the oceanographic cruise “INPULSE-19” at different stations with depths ranging from nearly 500 m to 1000 m depth. The distribution of the different organic matter fractions showed a high variability with marked differences between stations. The spatial distribution of phytopigments (PHYTOPIG) in the upper sediment layer (0-1 cm below the seafloor) evidenced high degree of accumulation at two close stations, where the higher PHYTOPIG concentrations were found, while PHYTOPIG concentrations were one other of magnitude lower at other sampling stations. Protein and carbohydrate concentrations in the water-soluble fractions (PROTWS and CHOWS) from the upper 0-1 cm sediment layer were correlated with each other, although they exhibited some differences in their spatial distribution pattern. Moreover, PROTWS in the 0-1 cm sediment layer was highly correlated to PHYTOPIG, suggesting a similar origin for both fractions, while the correlation with CHOWS was weaker. Alkaline extractable proteins and carbohydrates (PROTALK andCHOALK) were one order of magnitude higher than the concentrations in their respective water-soluble fractions. PROTALK andCHOALK in the 0-1 cm sediment layer were highly correlated with each other, showing a quite similar distribution pattern. The PROTWS/CHOWS ratio, an index of organic matter lability, ranged between 0.3 and 2.1 in the upper sediment layer, while the PROTALK/CHOALK ratio ranged between 1.6 and 3.6 The observed variability in these ratios indicates differences in the lability of sedimentary organic matter at different stations, which might affect the bioavailability of organic matter in the sediments.
Evaluating the efficacy of novel green fertilisers derived from combining carbon capture technology and organic waste materials  
Authors: Burak Emma , Sakrabani Ruben
Published: March 2022

Over‑reliance and indiscriminate use of mineral fertilisers have contributed towards declining soil health. Further, mineral fertiliser production contributes close to 1% of UK’s greenhouse gas emissions. Organo-mineral fertilisers (OMFs) are currently being investigated as a more environmentally sustainable alternative to conventional mineral fertilisers as they reduce the amount of mineral fertilisers needed by combining them with organic materials that would otherwise be destined for landfill or incineration, promoting a circular economy by returning recycled nutrients to the soil. Here, we evaluated the efficacy of a novel OMF that incorporates carbon captured from gaseous point sources into their production. This product demonstrates a potential tool for combating both climate change and soil fertility by promoting soil carbon sequestration. To assess the efficacy of these new fertilisers we conducted a field experiment consisting of three batches of OMF (5, 10 and 15%N) and compared them to a conventional mineral fertiliser and an unfertilised control in two soil types with two crops (winter barley and winter wheat).

We found that all fertilisers produced significantly more yield than the control (p < 0.05) but that there was no significant or consistent difference between the fertilisers. There was no significant or consistent differences between the stimulated root growth for any treatments (p = 0.60) and the same for organic matter, microbial biomass, pH, available nutrients (N, P, K), total nutrients (N, C, P), and metals. This leads to the conclusion that organo-mineral fertilisers can perform at least as well as conventional fertiliser. Though more seasons are needed to evaluate the benefits to the soil.
Changes on Aurora basin, East Antarctica, in coupled and uncoupled ice-ocean simulations
Authors: Haubner Konstanze , Van Achter Guillian , Pelletier Charles , Zipf Lars , Pattyn Frank
Published: March 2022

Ice mass loss on Greenland and Antarctica is a major contributor to sea level change and will thereby profoundly impact the world's infrastructure (e.g. transport, roads, ground water, housing) over the next decades. In order to react and adjust now accordingly, precise estimates of sea level change are needed. Though, future changes in sea level are provided by Earth system models, which rarely include ice sheet models, or by standalone ice sheet models. Hence, feedbacks between ice and atmosphere-ocean are overseen. Local scale coupled models can help bridging this gap by estimating how feedbacks between the different Earth systems affect global sea level estimates.

Here, we present results from a coupled simulation of the ocean-sea ice model NEMO3.6-LIM3 (1/24° grid ~ less than 2 km grid spacing) and the ice sheet model BISICLES (on 0.5-4km spatial resolution). The coupling routine is done via python code including variable exchange, pre- and postprocessing, done offline every 3 months, following the setup described in Pelletier et al., 2021.

Simulated ice mass changes, grounding line position and ice velocity changes of this high-resolution coupling scheme (between 1993-2014) are compared to observations and results of uncoupled simulations. We further discuss which processes might be neglectable and which are the main drivers of ice velocity acceleration and changes in sub-shelf ocean circulation.

 

Pelletier, C., Fichefet, T., Goosse, H., Haubner, K., Helsen, S., Huot, P.-V., Kittel, C., Klein, F., Le clec'h, S., van Lipzig, N. P. M., Marchi, S., Massonnet, F., Mathiot, P., Moravveji, E., Moreno-Chamarro, E., Ortega, P., Pattyn, F., Souverijns, N., Van Achter, G., Vanden Broucke, S., Vanhulle, A., Verfaillie, D., and Zipf, L.: PARASO, a circum-Antarctic fully-coupled ice-sheet - ocean - sea-ice - atmosphere - land model involving f.ETISh1.7, NEMO3.6, LIM3.6, COSMO5.0 and CLM4.5, Geosci. Model Dev. Discuss. [preprint], https://doi.org/10.5194/gmd-2021-315, in review, 2021.
The Antarctic and Greenland response to PlioMIP2 mPWP climatic fields
Authors: Blasco Javier , Tabone Ilaria , Moreno-Parada Daniel , Alvarez-Solas Jorge , Robinson Alexander , Montoya Marisa
Published: March 2022

Since the pre-industrial era, global sea level has been rising along with greenhouse gas emissions. Part of the contribution to this sea-level change is the mass lost from continental ice sheets, i.e. the Greenland (GrIS) and Antarctic (AIS) ice sheets, which are shrinking at an accelerated rate. However, how they will respond to future warming is highly uncertain due to our lack of knowledge and associated uncertainty in modelling several physical processes, as well as in warming projections. A way to gain insight into future projections is to study past warm periods that are, to some extent, comparable to the present day (PD) in terms of external forcing. The mid-Pliocene warm period (mPWP, 3.3-3.0 million years ago) offers an ideal benchmark, as it is the most recent period with CO2 levels comparable to PD (350-450 ppmv), showing global mean temperatures 2.5-4.0 degrees higher. Eustatic sea-level reconstructions from that period estimate a sea level 15-20 meters higher than PD, implying ice sheets were much smaller in size. The GrIS was starting to form and the AIS was most likely constrained to land-based regions. The Pliocene Model Intercomparison Project, Phase 2 (PlioMIP2) has brought together over 15 climate outputs from 11 General Circulation models from different institutions. These models have simulated mPWP conditions under 400 ppmv of CO2 concentration over a topography generated from an updated bedrock configuration for that time period. Here we use these model outputs to force offline a higher-order ice sheet model for the Antarctic and Greenland domain. Our aim is to investigate how polar continental ice sheets respond to these different climatic fields to pinpoint their most significant climatic and topographical discrepancies. In addition, several sources of structural dependence, from different dynamic states (i.e. basal friction laws) to different initial boundary conditions (starting from no ice-sheet to the PD configuration) are investigated in this modelling framework to create a comprehensive output database for statistical analysis.
Regional Precipitation Index: ranking storms in Greece
Authors: Lagouvardos Kostas , Papavasileiou George , Kotroni Vasiliki , Papagiannaki Katerina , Dafis Stavros , Galanaki Elisavet
Published: March 2022

The METEO unit of the National Observatory of Athens has developed a methodology for ranking rain storms in Greece, following a similar procedure in the USA, where ranking of snow storms is routinely performed. The rain storm ranking in Greece is performed through the calculation of the Regional Precipitation Index (RPI) which takes into account:

a)         The daily accumulated precipitation and its exceedance of specific percentile thresholds.

b)         The total area where these exceedances occur.

c)         The population of the area that these exceedances occur.

First, RPI calculations were applied in ERA5-Land rainfall re-analysis, available at 0.1 deg resolution, for a 30-year period spanning from 1991 to 2020 and all major storms that occurred within this period were ranked and correlated to the reported societal impacts. The ranking of the storms is performed based on the percentiles of all non-zero RPI in the examined period. As major storms we define the top 2% of RPI. Then, a proposed methodology for the application of the methodology on daily forecast fields provided by high-resolution numerical weather prediction models is tested and discussed.
An empirical analysis of the free core nutation period from VLBI-based series of celestial pole offsets
Authors: Belda Santiago , Ferrándiz Jose M. , Escapa Alberto , Modiri Sadegh , Puente Victor , Heinkelmann Robert , Schuh Harald
Published: March 2022

Currently, accurate observations of the Celestial Intermediate Pole (CIP) can only be obtained by the Very Long Baseline Interferometry (VLBI) technique. The differences among the observed CIP and that derived from IAU 2006/2000A precession-nutation model are the Celestial Pole Offsets (CPO). CPO contain the free core nutation (FCN), trends, and harmonics due to limitations of IAU precession-nutation model, geophysical excitations, etc. as well as the noise of observations. FCN is a free rotational mode of the Earth and, in principle, cannot be predicted. It can be determined from CPO time series with the use of different empirical models. The development of such models, and the enhancing of the existing ones, has been suggested in the IAU/IAG Joint Working Group ”Improving Theories and Models of the Earth’s Rotation (ITMER)”, since FCN contribution is the main one of CPO. The accurate estimation of the free core nutation (FCN) period of about 430 days is a challenging prospect. Comparison of the FCN period obtained by different authors and methods shows slight discrepancies. But, is there any evidence that the period of the FCN varies with time? If so, then this would complicate making a model of it. The FCN phase drift in 2000 could be related to that, but the is no clear evidence. In this study, we tested different FCN periods using several subsets of the observed nutations derived from VLBI analysis with the purpose of finding the optimal configuration that provides the lowest residuals. That is why a large quantity of empirical FCN models were also estimated and tested with different sliding window lengths and FCN periods. This analysis could bring us significantly closer to meet the accuracy goals pursued by the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG), i.e. 1 mm accuracy and 0.1 mm/year stability on global scales in terms of the ITRF defining parameters.

This research was supported partially by Generalitat Valenciana (SEJIGENT/2021/001) and the European Union—NextGenerationEU (ZAMBRANO 21-04) (S.B). This research was also supported by Spanish Projects PID2020-119383GB-I00 funded by Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033/) and  PROMETEO/2021/030 funded by Generalitat Valenciana (J.M.F., A.E.).
Assessment of Rockfall Hazard and 3D Trajectography based on Slope and Structural Settings: Case Study in Les Fréaux, France
Authors: Choanji Tiggi , Noël François , Fei Li , Sun Chunwei , Wolff Charlotte , Derron Marc-Henri , Bourrier Franck , Jaboyedoff Michel , Gaucher Romain
Published: March 2022

The case study is located in the municipality of Les Fréaux, France. The site consists of Cambrian-Ordovician of amphibolite and gneiss rock with complex structural geology that formed in mountainous and large valley with steep slopes and even overhanging rock walls. In this site, rockfall is a major hazard for access roads and houses.

To assess rockfall hazard in the vicinity of the elements at risk, LiDAR data have been analysed and field work done on site from 2020 to 2021.  Rockfall source areas were identified directly on 3D point clouds (PC) based on two criteria, which are large slope angles and kinematic analysis from structural identification of fault, folds and joints. Based on these source areas, several 3D point cloud trajectory models were processed using the freeware stnParabel, for various block diameters (d1, d2, d3) in order to determine the propagation and the probability of reaching the settlements or roads.

Preliminary simulation of trajectories based on several method of simulations results showed some potential directions are reaching the road and also leading to settlements.
OClO as continuously observed by TROPOMI on Sentinel 5P
Authors: Pukite Janis , Borger Christian , Dörner Steffen , Gu Myojeong , Wagner Thomas
Published: March 2022

Chlorine dioxide (OClO) is a by-product of the ozone depleting halogen chemistry in the stratosphere. Although being rapidly photolysed at low solar zenith angles (SZAs) it plays an important role as an indicator of the chlorine activation in polar regions during polar winter and spring at twilight conditions because of the nearly linear dependence of its formation on chlorine oxide (ClO).

The TROPOspheric Monitoring Instrument (TROPOMI) is an UV-VIS-NIR-SWIR instrument on board the Sentinel-5P satellite developed for monitoring the composition of the Earth’s atmosphere. It was launched on 13 October 2017 in a near polar orbit. It measures spectrally resolved earthshine radiances at an unprecedented spatial resolution of around 3.5x7.2 km2 (3.5x5.6 km2 starting from 6 Aug 2019) (near nadir) with a total swath width of ~2600 km on the Earth's surface providing daily global coverage and even higher temporal coverage in polar regions. From the measured spectra high resolved trace gas distributions can be retrieved by means of differential optical absorption spectroscopy (DOAS).

We compare slant column densities (SCDs) of chlorine dioxide (OClO) obtained from TROPOMI measurements with meteorological data and CALIPSO Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) polar stratospheric cloud (PSC) observations for both Antarctic and Arctic regions for the time period since TROPOMI launch in 2017 till now.
Asymmetrical lithospheric necking of Red Sea rift 
Authors: Aldaajani Thamer , Khalil Hany , Ball Philip , Capitanio Fabio , Almalki Khalid
Published: March 2022

The Red Sea rift exhibits two distinct rifting styles: in the north, the rifting is magma-poor, the crust is hyperextended and the lithospheric necking is asymmetric, in the south, rifting rapidly localized atop a symmetric lithospheric necking. One of the long-standing questions is what drives such different lithospheric necking style? We ran 2D high-resolution thermomechanical numerical simulations of lithospheric rifting to address the northern and southern Red Sea extensional end members and validate the models’ deformation patterns by comparing them against 2D data-driven structural models. The modelling investigates (a) the effect of rotational extension by varying extension velocities along the Red Sea, and (b) the thermal structure of the southern Red Sea due to plume impingement, while the analysis of the outcomes focuses on the early rifting stage, which involves normal rifting and dike intrusion. We find that asymmetrical lithospheric necking in the central and northern Red Sea is potentially driven by the velocity boundary conditions and inherited structures, mainly the Sirhan rift. The decoupling between the upper portion of the lithosphere and the asymmetrical lithospheric necking, which plays an essential role in the observed deformation patterns in the Arabian margin, is likely controlled by the lower crustal rheology and thickness. Furthermore, we find that the Afar plume near the southern Red Sea, which introduced in our models in form of thermal anomaly, promotes rifting localization.
Sub-regional marine heat waves in the Mediterranean Sea
Authors: Juza Melanie , Fernandez-Mora Angels , Tintore Joaquin
Published: March 2022

In a warming world, society is facing major climate-related challenges and impacts, such as marine heat waves (MHW) that have devastating effects on ecosystems, threaten economies and strengthen severe storms. MHWs are substantially increasing in intensity, duration and frequency worldwide and particularly in the Mediterranean Sea. This semi-enclosed and relatively small basin responds rapidly to global warming experiencing strong spatial variations that require specific consideration, in particular to better understand the drivers, mechanisms and consequences of such extreme events on the physical, biogeochemical and biological components of the oceans.

This study proposes a comprehensive characterization of MHWs in the Mediterranean at sub-regional scale from surface to sub-surface and from open to coastal waters, using remote sensing and multi-platform in situ observations. First, the long-term evolution of MHW characteristics (mean and maximum intensities, mean duration and frequency) is analysed at sub-regional scale using the satellite observations of sea surface temperature over the last four decades. Then, the propagation of sub-regional MHWs into the ocean interior and the associated modified stratification are examined through the use of vertical hydrographic profiles from profiling floats. Finally, the ocean response to extreme temperature events is also investigated in the coastal ocean complementing the satellite observations with mooring data in the near-shore waters of the Balearic Islands.

A smart platform has been implemented to monitor, visualize and share timely information on sub-regional MHWs, from event detection in real-time to long-term variations in response to climate change, to diverse stakeholders (e.g., scientific community, educators in marine science, environmental agencies and policy decision-makers). The “Sub-regional Mediterranean Marine Heat Waves” visualization tool will help to implement adaptive management, to establish adaptation strategy and to support the marine conservation and sustainable management of the oceans in a warming world.
Observation of Simultaneous Etna Volcanic aerosol and Desert Dust aerosol over Naples: an experimental test for a new lidar inversion algorithms 
Authors: Sannino Alessia , Amoruso Salvatore , Damiano Riccardo , Scollo Simona , Sellitto pasquale , Boselli Antonella
Published: March 2022

Studies on the spatio-temporal characterization of microphysical and optical properties of atmospheric aerosol are of particular interest for their impacts on life cycle. Unfortunately, large uncertainties govern these studies because of the wide variability of the components which characterize the aerosol, especially when several sources concur in the observations. This is exactly what happens over the Central Mediterranean where particles of different nature and typology, produced by local sources or long-range transport phenomena from natural and anthropogenic sources, coexist frequently in the aerosol layers. Among these contributions, a special mention deserves the volcanic activity, since Mediterranean area hosts numerous active volcanoes, like Mount Etna, in Italy, whose degassing and explosive activities have a strong impact on the atmospheric aerosol composition. In this work we present the results from the Etna paroxysmal event occurred  in February 21st - 26th, 2021 and observed in the Naples area in coexistence with Saharan dust transport. The event has been characterized by the ACTRIS (Aerosol, Clouds and Trace Gases Research Infrastructure) observation station of the University of Naples “Federico II” by combining lidar, sunphotometer and satellite data. Back-trajectories and volcanic plume dispersion simulations were also performed in order to better distinguish geometrical, optical and microphysical properties of the atmospheric aerosol. From our analysis, spatio-temporal information of the two main aerosol components in terms of their optical  and microphysical proprieties were clearly identified. In particular, starting from lidar data, the particle size distributions were retrieved at desired altitudes using a novel inversion approach based on a new Monte Carlo algorithm. Interestingly, when integrated over the range on the observation column, the experimental findings result in good agreement with the data provided by the sunphotometer.
On the relationship between Polarimetric Radio Occultation observables and water content for convective systems at different life stages
Authors: Padullés Ramon , Paz Antía , Cardellach Estel , Turk F. Joe , Ao Chi O. , de la Torre Manuel , Wang Kuo-Nung , Oyola Mayra , Schiro Kathleen
Published: March 2022

Accurate prediction and modeling of heavy precipitation events remains an issue due to gaps in our understanding of the physical processes underlying them. Such gaps arise from the limited number of good quality observations that constrain the thermodynamic parameters (e.g. temperature, moisture, etc.) within heavy precipitation, since the observations of some space-based sensors are degraded in the presence of thick clouds.

The Global Navigation Satellite System (GNSS) Polarimetric Radio Occultation (PRO) technique was recently created to overcome some of these limitations, by providing vertical profiles of temperature, pressure, and water vapor, along with vertical information about hydrometeors (i.e. raindrops, snow, ice crystals, etc), simultaneously. It represents an enhancement of the standard radio occultation technique, that consists on tracking the signals emitted by GPS satellites from a low Earth orbit satellite occulting behind the Earth’s horizon. These signals cross lower and denser layers of the atmosphere as the occultation advances. The augmentation that the polarimetry provides consists on collecting these signals using two linearly and orthogonal polarized antennas (H and V), instead of the circularly polarized one used in the standard technique. Comparing the phase of the signals received at the two antenna ports, we can infer the presence of hydrometeors along the ray paths. Polarimetric Radio Occulation technique is being proved aboard the PAZ satellite, in an experiment led by the Institut de Ciències de l’Espai (ICE-CSIC,IEEC), in collaboration with NOAA, UCAR and NASA/Jet Propulsion Laboratory, operating since 2018. These profiles are obtained globally, through all kinds of clouds and over all kinds of surfaces. Such characteristics are rather unique in the current observing system.

For this study, mesoscale convective systems (MCS) are particularly of interest. Given the characteristics of the observational technique and the targeted systems, it is relatively easy to find collocated measurements. Therefore, we can study the nature of the vertical structure of the hydrometeors within the cloud structure of MCS, depending on their life stage (e.g. initiation, maturity, decay) and relative position (e.g. leading vs trailing), with the help of geostationary infrared imagery. Unique insights obtained with the new PRO technique will be presented.
Underestimated increase in duration of annual meteorological drought in future climate projections
Authors: Yu. Petrova Irina , G. Miralles Diego , Brient Florent , Donat Markus , Kim Yeon-Hee , Min Seung-Ki
Published: March 2022

The increasing risk of dry extremes and droughts and their further projected exacerbation due to climate change urges the development of reliable risk assessments and mitigation pathways on a regional and global scale. This foremost requires accurate and unambiguous model predictions of dry extremes, as this underpins the effectiveness of the proposed strategies. At present, however, the confidence in regional drought projections is defined as ‘medium to low' by the Intergovernmental Panel on Climate Change (IPCC) sixth assessment report (AR6), and reducing this uncertainty remains one of the main goals in coming years.
In this study, the bias in future projected changes in annual meteorological drought duration (hereafter, longest annual drought, LAD) is assessed in the ensemble of CMIP5 and CMIP6 models. The analyses show that it is the present-day inter-model spread in LAD climatology that largely determines the inter-model uncertainty in future predicted LAD changes. Hereby, both CMIP5 and CMIP6 model ensembles indicate a robust “dry-model-gets-drier” relationship in future LAD projections on a global and regional scale. Correcting for this bias using emerging constraint principles and past observational LAD information, we find that nearly half of the world's land area with projected increases in drought duration is underestimating the predicted model ensemble mean change, imposing higher-than-expected risks to the societies and ecosystems. Analysis of physical mechanisms that could underlie this emergent “present-future relationship” points to differences in the responses of “dry models” and “wet models” to CO2 forcing. Dry and wet models show differences in climate states, which support the role of land–atmosphere feedbacks and convective scheme sensitivity to atmospheric moisture in the spread of future LAD change projections.
In conclusion, the study reveals world regions where climate change may cause stronger drought duration aggravation than expected, and emphasizes the importance of reducing systematic model errors, which are presently largely owed to rainfall biases. Correcting these biases will increase the confidence of future dry extremes predictions, a prerequisite for the effective drought risk reduction in the near future with direct benefits for human and natural systems.
The anthropogenic imprint on temperate and boreal forest age structure and carbon turnover
Authors: Pugh Thomas A M , Seidl Rupert , Liu Daijun , Lindeskog Mats , Chini Louise P , Senf Cornelius
Published: March 2022

The sweeping transformation of the biosphere by humans over the last millennia leaves only limited windows into its natural state. Much of the forests that dominated temperate and southern boreal regions have been lost and those that remain typically bear a strong imprint of harvest activity. Here, we ask how would the dynamics, structure and function of temperate and boreal forests differ in the absence of harvest? We focused our analysis on the human-induced shift in forest disturbance dynamics and its resultant effects on forest age structure and carbon cycling. We constructed an empirical model of natural disturbance probability as a function of community traits and climate, based on observed disturbance rate and form across 77 protected forest landscapes distributed across three continents. Coupling this to a dynamic vegetation model, we generate estimates of stand-replacing disturbance return intervals and calculate the forest age structure that results. We compare this to best estimates of current age structures based on (a) past land-use change and management and (b) forest inventory observations. Modern forests are typically much younger than those under natural disturbance only, with 43% less old-growth stands. This results in a 33% reduction in vegetation carbon turnover time across temperate forests and a 14% reduction for boreal forests. Understanding the state and dynamics of forests in the absence of harvest provides context for making decisions related to global conservation and climate change mitigation efforts, especially related to nature-based solutions.
Scattering database of dust particles with realistic shapes
Authors: Tsekeri Alexandra , Gasteiger Josef , Konoshonkin Alexander , Kustova Natalia , Georgiou Thanasis , Amiridis Vassilis
Published: March 2022

We constructed a new scattering database that takes into account realistically-shaped dust particles and a size range that includes most of the coarse mode of desert dust. In particular, we have used the irregular shapes of Gasteiger et al. (2011), a size parameter range of 0.01-60 and four refractive indices with values of 1.48-1.6+i0-0.002. The scattering calculations were performed with the Amsterdam Discrete Dipole Approximation (ADDA) (Yurkin and Hoekstra, 2011) using ~60M CPU core hours on High Performance Computing (HPC) systems.

Currently, there is no complete solution for calculating the scattering properties of the whole range of dust sizes, shapes and refractive indices. For size parameters >~60 ADDA calculations are challenging even for HPC machines, due to their high computational cost (Yurkin and Hoekstra, 2011). For this reason, we investigate the applicability of the much faster Physical Optics (PO) approximation (Konoshonkin et al., 2017) for dust particles with faceted shapes. We compare the PO scattering calculations with ADDA calculations and we present here the issues and perspectives of this coupling in formulating a complete scattering database for dust. 

 

 

References

Gasteiger, J., M., Wiegner, S., Gross, V., et al.: Modeling lidar-relevant optical properties of complex mineral dust aerosols, Tellus B 63, 725–741, 2011.

Yurkin, M. A., and A. G., Hoekstra: The discrete-dipole-approximation code ADDA: capabilities and known limitations, J. Quant. Spectrosc. Radiat. 112, 2234–2247, 2011.

Konoshonkin, Α., A. Borovoi, N. Kustova, et al.: Light scattering by ice crystals of cirrus clouds: From exact numerical methods to physical-optics approximation, J. Quant. Spectrosc. Radiat. Transf. 195, 132–140, 2017.
Coastal Blue Carbon Storage, Sources and Accumulation in Gautami-Godavari (Coringa) Mangrove sediments
Authors: rao Karuna , jennerjahn Tim , al Ramanathan , nj Raju
Published: March 2022

The mangrove ecosystem is an important natural sink of carbon owing to its potential to accumulate and store large amounts of organic carbon, in particular in its anaerobic sediments. To better understand the role of and quantify this carbon sink, the present study measured organic carbon stocks, carbon accumulation rates, and organic matter sources in the sediments of the Gautami-Godavari (Coringa) mangrove ecosystem, Andhra Pradesh, India. The carbon and nitrogen stable isotopic composition and elemental ratios of total organic carbon (TOC) to total nitrogen (TN) have been used to detect the sedimentary organic matter sources in the Coringa mangrove complex. 210Pb isotopes have been used to determine the sedimentation rates and carbon accumulation rates. The value of ∂13C ranges from -17.8‰ and -26.1‰ with an average value of -23.3‰ and TOC/TN ranges from 9-27 with an average value of 15. The spatial variation of all sedimentary parameters i.e., TOC, TN, ∂13C, and ∂15N is found to be significant at various sites. Both Sedimentary Carbon Stock and Carbon Accumulation Rates also have significant spatial variation among different sites and their values are maximum in an area where mangroves are directly affected by aquaculture effluents. The lowest carbon stock has been observed in an area where mangroves are degraded. The scatter plot between δ13C and TOC/TN ratio reveals that most of the sedimentary organic matter originated from non-mangrove sources like algae, phytobenthos, and suspended particulate matter.
Correction of Monthly SST Forecasts in CFSv2 Using the Local Dynamical Analog Method
Authors: Hou Zhaolu , Li Jianping , Zuo Bin
Published: March 2022

Numerical seasonal forecasts in Earth science always contain forecast errors that cannot be eliminated by improving the ability of the numerical model. Therefore, correction of model forecast results is required. Analog correction is an effective way to reduce model forecast errors, but the key question is how to locate analogs. In this paper, we updated the local dynamical analog (LDA) algorithm to find analogs and depicted the process of model error correction as the LDA correction scheme. The LDA correction scheme was first applied to correct the operational seasonal forecasts of sea surface temperature (SST) over the period 1982–2018 from the state-of-the-art coupled climate model named NCEP Climate Forecast System, version 2. The results demonstrated that the LDA correction scheme improves forecast skill inmany regions as measured by the correlation coefficient and root-mean-square error, especially over the extratropical eastern Pacific and tropical Pacific, where the model has high simulation ability. El Niño–Southern Oscillation (ENSO) as the focused physics process is also improved. The seasonal predictability barrier of ENSO is in remission, and the forecast skill of central Pacific ENSO also increases due to the LDA correction method. The intensity of the ENSOmature phases is improved.Meanwhile, the ensemble forecast results are corrected, which proves the positive influence from this LDA correction scheme on the probability forecast of cold and warm events. Overall, the LDA correction scheme, combining statistical and model dynamical information, is demonstrated to be readily integrable with other advanced operational models and has the capability to improve forecast results.
A new Educational Open-source eBook for Modeling River Hydro-morphodynamics
Authors: Schwindt Sebastian , Scolari Federica
Published: March 2022

The analysis of hydro-morphodynamic processes in river ecosystems involves modeling complex natural processes based on continuously growing data sets. Typical tools involved in such analyses embrace numerical models, GIS software, and high-level programming languages. Teaching the application of these tools is part of many environmental and geoscience-oriented study courses though the tool development partly roots in other disciplines, such as civil or software engineering. Thus, the holistic understanding of tools for hydro-morphological modeling and assessment of river ecosystems is an interdisciplinary challenge that is often solved in practice through multi-institutional collaboration. Yet, even public academic institutions tend to teach the usage of proprietary software that is embedded in a chain of even more, often expensive, proprietary software applications. In addition, the teaching of software refers to a presently up-to-date version, and its application can quickly become outdated.

To address the challenge of teaching interdisciplinary tools for modeling and analyzing river ecosystems, we have created an online eBook (available at https://hydro-informatics.com) that exclusively explains the use of open-source and open-access software. The eBook goes beyond our institutional teaching, and we do our best to keep the descriptions of software applications up-to-date. In addition, we offer more than IT assistance through detailed explanations of physical processes and mathematical equations involved in river ecosystem modeling. For instance, we explain geomorphological principles and the development of equations for calculating fluvial sediment transport. In cross-disciplinary application examples, we also feature ecohydraulic principles of river landscape analysis, for example, to calculate habitat suitability based on two-dimensional numerical model outputs. To this end, we explain and demonstrate the installation and use of the high-level programming language Python, the numerical modeling software BASEMENT and TELEMAC, the usage of git and Markdown, and the geospatial software QGIS on common operating systems (including and with preference: Linux). Ultimately, we also offer sample data sets, self-learning checks, exercises, and troubleshooting solutions to keep the barrier to free teaching as low as possible.