bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a dynamic dust-source map for regional dust models based on MODIS NDVI 
Authors: Solomos Stavros , Spyrou Christos , Bartsotas Nikos , Nickovic Slobodan
Published: March 2022

The proper representation of dust production in numerical weather prediction (NWP) models depends largely on the detailed mapping of the arid areas that act as natural dust sources. The extend and the strength of these sources varies throughout the year based on aridity and vegetation properties. Such changes are monitored from spaceborne platforms (e.g. MODIS NDVI index). In this work we present a methodology for including a dynamic dust source map in the state-of-the-art NMME-DREAM and WRF-Chem models. This time-varying dust source map is based on the 1000m 16-day averaged Normalized Difference Vegetation (NDVI) from the MODIS/Terra instrument. The methodology is first tested with DREAM-NMM over the Arabian Peninsula. The results indicate significant improvement in simulated AODs over AERONET stations compared to the runs driven by the standard static dust source map. The modeled AOD bias in NMME-DREAM is improved from -0.140 to 0.083 for AOD>0.25 and from -0.933 to -0.424 for dust episodes with AOD> 1. Afterwards we apply the above methodology to the Air Force Weather Agency (AFWA) dust emission module in WRF-Chem model. WRF-Chem has been selected due to its nesting capabilities that permit finer resolution simulations of local scale dust processes. Two sets of simulations have been performed covering the entire Saharan desert, the Mediterranean, Europe and part of the Arabian Peninsula, at a horizontal resolution of 12×12 Km: (1) WRF-Chem control simulations, where dust sources are defined based on the original AFWA code and (2) WRF-Chem experimental simulations where the erodibility of the selected domain is modified based on MODIS NDVI. The selected test period is April 2017 when significant Saharan dust outbreaks took place over the Mediterranean. The simulated AOD from both sets of model runs are validated against AERONET stations. First results verify the successful implementation of the dynamic dust source module in WRF-Chem.  The experimental (NDVI) simulations showed an overall increase in dust loads over the entire domain and an improved performance, mostly in areas close to the Saharan desert.
Imaging of the Quiet Sun in the Frequency Range of 20-80MHz
Authors: Zhang Peijin , Zucca Pietro , Kozarev Kamen , Wang Chuanbing , Team Lofar ssw ksp
Published: March 2022

Radio emission of the quiet Sun is generally believed to be generated from thermal bremsstrahlung emission of the hot solar atmosphere. The imaging properties of the quiet Sun in the microwave band have been well studied, and they fit well to the spectrum of bremsstrahlung emission. In the meter-wave and decameter-wave bands, imaging properties of the quiet Sun have rarely been studied due to the instrumental limitations. In this work, we use the LOw Frequency ARray (LOFAR) telescope to perform high-quality interferometric imaging spectroscopy observations of quiet Sun coronal emission at frequencies below 90~MHz. In these observations of the coronal emission, we achieved unprecedented imaging quality, spatial structures are well resolved. For the first time, we find dark regions with low brightness temperatures. The brightness temperature spectrum of the quiet Sun is obtained and compared with the bremsstrahlung emission of the corona model. 
Ocean Interaction and the Intensity Evolution of Two High-Impact Super Typhoons: Hagibis (2019) and Haiyan (2013)
Authors: Lin Ii , Rogers Robert F. , Huang Hsiao-Ching , Liao Yi-Chun , Herndon Derrick , Yu Jin-Yi , Chang Ya-Ting , Zhang Jun A. , Patricola Christina M. , Pun Iam-Fei , Lien Chun-Chi
Published: March 2022

Devastating Japan in October 2019, Supertyphoon (STY) Hagibis was an important typhoon in the history of the Pacific. A striking feature of Hagibis was its explosive RI (rapid intensification). In 24 h, Hagibis intensified by 100 kt, making it one of the fastest-intensifying typhoons ever observed. After RI, Hagibis’s intensification stalled. Using the current typhoon intensity record holder, i.e., STY Haiyan (2013), as a benchmark, this work explores the intensity evolution differences of these 2 high-impact STYs.

We found that the extremely high pre-storm sea surface temperature reaching 30.5∘C, deep/warm pre-storm ocean heat content reaching 160 kJ cm-2, fast forward storm motion of ~8 m s-1, small during-storm ocean cooling effect of ~ 0.5∘C, significant thunderstorm activity at its center, and rapid eyewall contraction were all important contributors to Hagibis’s impressive intensification. There was 36% more air-sea flux for Hagibis’s RI than for Haiyan’s.

After its spectacular RI, Hagibis’s intensification stopped, despite favorable environments. Haiyan, by contrast, continued to intensify, reaching its record-breaking intensity of 170 kt. A key finding here is the multiple pathways that storm size affected the intensity evolution for both typhoons. After RI, Hagibis experienced a major size expansion, becoming the largest typhoon on record in the Pacific. This size enlargement, combined with a reduction in storm translational speed, induced stronger ocean cooling that reduced ocean flux and hindered intensification. The large storm size also contributed to slower eyewall replacement cycles (ERCs), which prolonged the negative impact of the ERC on intensification.
Effect of wildfire on stemflow velocity of pine
Authors: Zhang Yusen , Wang Lunjiang
Published: March 2022

Stemflow, as one of the most important elements of forest precipitation redistribution, affects the delivery and spatial distribution of water and nutrient. Although approximately 4% of forests are affected by wildfire worldwide, no study has measured stemflow velocity after forests are affected by wildfire. The aim of this study is to determine (1) whether stemflow velocity changes after wildfire, (2) whether stemflow velocity changes with stem flow rate and height, (3) whether stem surface roughness affects stemflow velocity. In this study, we designed a device to quantify stemflow velocity. Our study revealed that the destructions of bark morphology and biological crust on the stem surface were the main factors affecting the change of stemflow velocity. The wildfire caused an enhanced stemflow velocity by roughly 30% for the burned pine compared to pine that did not affect by the wildfire. The stemflow velocity increased with stemflow rate following a power function. The width of pine bark had a negative linear relationship with stemflow velocity. With the increase in stemflow rate, the difference in stemflow velocity between burnt pine and unburnt pine was not significant. Stemflow velocity did not increase with the height of stemflow starting point increased, probably because increased stemflow energy caused the stemflow to detach from the stem. This study implies stemflow velocity affected the migration rate and spatial distribution of water and nutrient on stems and land surface around the base of tree. The increased stemflow energy is also likely to exacerbate soil erosion. All these can affect the restoration process of forest ecosystems from wildfire.
The PBL and other thermodynamic indices for the study of climate change
Authors: Summa Donato , Madonna Fabio , Franco Noemi , De Rosa Benedetto , Rosoldi Marco , Di Girolamo Paolo
Published: March 2022

The height of the planetary boundary layer is strongly influenced by the surface of the earth since it is directly in contact with it. In this study  we want to discuss the correlation between global warming and PBL variation. This is addressed using both the boundary layer height and other thermodynamic indices. In this study we want to highlight how the variation in the height of the PBL, together with other thermodynamic indices, represent an indication of climate change. PBL variations are therefore analyzed both in the daytime and in the night case, by means of radiosonding profiles from the Global Integrated Archive (IGRA) at the mid-latitudes in the range [30 °; 50 °] N. Data from the European Center for Medium-Range Weather Forecasting (ECMWF) and all the GRUAN station in the same latitude belt station GCOS Upper-Air Network (GRUAN) are used as a comparison dataset for atmospheric parameter uncertainties. 

The study reports a statistical analysis over 40 years, in order to have an evolution of thermodynamic variables both on monthly,  seasonal averages and also  annual. In general, a good agreement is found for the nighttime data compared between IGRA and ERA5, while during the day, the boundary layer height estimates in Europe with ERA5 are characterized by lower spatial homogeneity than those obtained with IGRA.

Finally, the comparison between the Lindenberg data as processed at high-resolution by GRUAN and as provided to IGRA at a lower resolution, shows the significant impact of using high-resolution data in the determination of the boundary layer height. [1,2]

[1] Madonna, F., Summa, D., Di Girolamo, P., Marra, F., Wang, Y., Rosoldi, M. Assessment of Trends and Uncertainties in the Atmospheric Boundary Layer Height Estimated Using Radiosounding Observations over Europe. Atmosphere 2021, 12, 301. https://doi.org/10.3390/atmos12030301

[2] Vivone G., D’Amico G., Summa D., Lolli S., Amodeo A., Bortoli D., and Pappalardo G. Atmospheric boundary layer height estimation from aerosol lidar: a new approach based on morphological image processing techniques. Atmos. Chem. Phys., 21, 4249–4265, 2021,https://doi.org/10.5194/acp-21-4249-2021
Open-Ocean Polynyas in the Cooperation Sea, Antarctica
Authors: Qin Qing , Wang Zhaomin , Liu Chengyan , Chen Cheng
Published: March 2022

     Extensive studies have addressed the characteristics and mechanisms of open-ocean polynyas in the Weddell and Cosmonaut Seas. Here, we show that more persistent open-ocean polynyas occur in the Cooperation Sea (CS) (60°E-90°E),  a sector of the Southern Ocean off the Prydz Bay continental shelf,  between 2002 and 2019. Polynyas are formed annually mainly within the 62°S-65°S band, as identified by sea ice concentrations less than 0.7. The polynyas usually began to emerge in April and expanded to large sizes during July-October, with sizes often larger than those of the Maud Rise polynya in 2017. The annual maximum size of polynyas ranged from 115.3 × 103 km2 in 2013 to 312.4 × 103 km2 in 2010, with an average value of 188.9 × 103 km2. The Antarctic Circumpolar Current (ACC) travels closer to the continental shelf and brings the upper circumpolar deep water to much higher latitudes in the CS than in most other sectors; cyclonic ocean circulations often develop between the ACC and the Antarctic Slope Current, with many of them being associated with local topographic features and dense water cascading. These oceanic preconditions, along with cyclonic wind forcing in the Antarctic Divergence zone, generated polynyas in the CS. These findings offer a more complete circumpolar view of open-ocean polynyas in the Southern Ocean and have implications for physical, biological, and biogeochemical studies of the Southern Ocean. Future efforts should be particularly devoted to more extensively observing the ocean circulation to understand the variability of open-ocean polynyas in the CS.
Extreme sea levels and wind-waves in the Mediterranean Sea since 1950
Authors: Toomey Tim , Amores Angel , Marcos Marta , Orfila Alejandro
Published: March 2022

In the Mediterranean Sea, coastal extreme sea levels are mainly caused by storm surges driven by atmospheric pressure and surface winds from extratropical cyclones. In addition, wind-waves generated by the same atmospheric perturbations may also contribute to coastal extremes through wave setup (a temporary rise in mean sea level due to waves breaking close to shore). This study investigates the spatial and temporal variability of coastal extreme sea levels within the Mediterranean basin, using a new ocean hindcast generated with a coupled hydrodynamic-wave model that simulates storm surges and wind-waves generation and propagation. The numerical simulation spans the period 1950-2020 and is run with high temporal sampling (1h) and at unprecedented spatial resolution that reaches 200 m along the coastlines. Coastal storm surges and wave heights have been extensively validated with available observations (tide gauges and waves buoys). Comparison to tide gauges shows an average RMSE of 0.05m (0.08m for extreme events) and linear correlation of 0.75 for the period covering 1980-2020. Similarly, comparison of simulated and observed significant wave height shows good agreement with RMSE lower than 0.25 m and coefficient correlation as high as 0.95. Preliminary results show that coastal extreme sea levels found are more likely to be located in regions with wide and shallow continental shelves, where mild slope favour the combined effects of wind and wave setup. The contribution of waves to coastal extreme sea levels has been explored with an uncoupled simulation and has been shown to be significant, reaching up to 120% of observed maximum sea levels.
Formaldehyde column retrievals from the GEMS mission and evaluation against TROPOMI data
Authors: De Smedt Isabelle , Van Gent Jeroen , Vlietinck Jonas , Yu Huan , Lerot Christophe , Theys Nicolas , Pinardi Gaia , Hendrick François , Romahn Fabian , Park Rokjin , Lee Gitael , Kwon Hyeong Ahn , Loyola Diego , Van Roozendael Michel
Published: March 2022

Atmospheric formaldehyde (HCHO) is a secondary product in the destruction of non-methane volatile organic compounds (NMVOCs), through both natural and anthropogenic processes. With a relatively short lifetime of a few hours, the HCHO concentrations are usually localised close to their source. Measuring HCHO from space is therefore highly relevant in obtaining information on NMVOC emissions and their role in air quality and climate. HCHO retrievals from space have so far been limited to polar orbiting sensors with a fixed local overpass time.

The Geostationary Environment Monitoring Spectrometer (GEMS), launched on-board the GEO-KOMPSAT-2B satellite in February 2020 is the first geostationary sensor dedicated to air quality and atmospheric composition measurements. GEMS (observing South-East Asia hourly) will be complemented by TEMPO in 2022 (United States) and Sentinel-4 in 2023 (Europe and Northern Africa). Those instruments will provide an unprecedented hourly revisit time in their respective spatial domains. However, geostationary sensors make fundamentally different demands on the HCHO algorithm as compared to polar sensors.

In this work, we present DOAS tropospheric column retrieval results for HCHO from GEMS. In order to fit the SCD, a precise wavelength calibration is applied and potential changes in the instrumental line shape are accounted for. Polarisation spectral structures and scene heterogeneity effects are included, and a background correction and destriping procedure dedicated to geostationary observations is also developed. Air mass factors are calculated using auxiliary data consistent with the TROPOMI operational product. We compare our first results with those from TROPOMI in the early afternoon and with the GEMS HCHO operational product. Finally, we examine the diurnal variations observed with GEMS over different emission sources. MAX-DOAS measurements are used to validate and interpret the observed hourly variations.
Transport and removal of spores of Bacillus subtilis in an alluvial gravel aquifer at varying flow rates and implications for setback distances
Authors: Oudega Thomas James , Lindner Gerhard , Sommer Regina , Farnleitner Andreas , Kerber Georg , Derx Julia , Stevenson Margaret E. , Blaschke Alfred Paul
Published: March 2022

To minimize the risk of waterborne disease outbreaks, drinking water wells should have a sufficiently large setback distance from potential sources of contamination, e.g. a nearby river. The aim of this study was to provide insight in regards to microbial contamination of groundwater under different hydraulic gradients, which can vary over time due to changes in river stage, season or pumping rate. The effects of these changes, and how they affect removal parameters, are not completely understood. In this study, field tracer tests were carried out in Vienna, Austria to evaluate the ability of subsurface media to attenuate Bacillus subtilis spores, used as a surrogate for Cryptosporidium and Campylobacter. The hydraulic gradient between injection and extraction was controlled by changing the pumping rate (1, 5 or 10 l/s) of a pumping well at the test site.  Attachment and detachment rates were determined using a HYDRUS-3D model and setback distances were calculated based on the 60-day travel time, as well as a quantitative microbial risk assessment (QMRA) approach. It was shown that scale must be taken into consideration when determining removal rate (λ), which is crucial for the calculation of setback distances, and that the effect of flow rate becomes more important at lower removal rates.
Multi-method attribution of the extreme precipitation and flood of 2018 in Kerala, India.
Authors: Dhasmana Manish Kumar , Mondal Arpita , Zachariah Mariam
Published: March 2022

The role of global warming and climate change in altering the likelihood of extreme weather events is becoming increasingly evident. Event attribution refers to the collection of frameworks that use observed data and climate model simulations for quantifying the contribution of human-induced (anthropogenic) climate change in changing the event probability. In this study, we present a multi-method event attribution analysis of the catastrophic extreme precipitation and flooding event in Kerala, India in August 2018, that resulted in widespread destruction and loss of lives. Two methods- (i) based on factual (Historical) and counterfactual (HistoricalNat) runs from 5 CMIP6 climate models, and (ii) based on observed data, scaled to 2018 (factual) and 1901(pseudo-counterfactual) climates, are considered for quantifying the fraction of attributable risk (FAR) of the 2018 event. Using an objective approach, we first define the 2018 event as the 4-day cumulative rainfall over the Periyar river basin (PRB), during 15- 18 August, 2018. This event has a return period of 373 years (90% CI: 72-1200 years). The 1-day maximum streamflow at one of the outlets of the PRB, where maximum impact during the event was reported, is used for attributing the associated flood event. Simulated using VIC hydrological model, the streamflow event is found to have a return period of 34 years (90% CI: 12-286 years). The FAR from the climate model ensembles is -0.18 and -0.14, for the precipitation and streamflow events, respectively. The scaled observations also give negative FARs: -0.97 for precipitation and -0.93 for streamflow. These values imply that the 2018 event is exceptionally less likely due to climate change. In other words, our results underline the definitive absence of anthropogenic role in the 2018 event.
Tsunami Mitigation Map and Evacuation Route Modeling on the Jetis Beach, Cilacap Regency, Indonesia using Scoring Method and Dijkstra’s Algorithm
Authors: Laksono Anjar Tri , Widagdo Asmoro , Aditama Maulana Rizki , Fauzan Muhammad Rifki , Kovacs Janos
Published: March 2022

The tsunami that occurred on the Southern Coast of West Java and Central Java resulted in 802 people killed, 498 people injured, and 1623 houses heavily damaged. The total economic loss and damage to infrastructure due to this disaster reached US$55 million. The impact of this disaster in Jetis Village, Cilacap, Central Java was 12 people died, Jetis Beach tourist facilities were damaged, transportation infrastructure was destroyed, and hundreds of houses collapsed. The Jetis area and its surroundings are very close to vital national infrastructures such as the Cilacap steam power plant that supplies electricity to southern Java and the Cilacap container port. In addition, this area is a tourist attraction visited by thousands of people per year. Therefore, the purpose of this research is to create a tsunami disaster mitigation map and evacuation route in Jetis Village to anticipate future casualties and economic losses. The method used in this study is scoring to create a tsunami mitigation map and Dijkstra's algorithm to determine the fastest evacuation route. The results depict that there are five zones of tsunami vulnerability, namely high impact potential, moderately high, moderate, moderately low, and low impact potential. The most vulnerable tsunami is the South Jetis area that has low elevation, is near the coast, fairly gentle slope, and is close to the river. Meanwhile, the northern part of Jetis is the safest zone of tsunami hazard. It has a high elevation, far from the coastline and river, and a steep slope. The distance of the evacuation route from the high-impact zone to the safe evacuation zone is 683 m. This study concludes that the high-impact to moderate-impact zone needs to be avoided in the event of a tsunami. If the community is within that range zone, then an evacuation route should be followed.
Hygroscopicity and Ice Nucleation Properties of Dust/Salt Mixture Originated from the Source of East Asian Dust Storm
Authors: Li Jun , Liu Wanyu , Wenjun Wenjun , Li Linjie , Tang Mingjin , Hallquist Mattias , Wang Sen , Kong Xiangrui
Published: March 2022

Dust storms are common meteorological disasters which occur frequently in the late spring and early summer in arid and semi-arid areas. Deserts in North Africa, Middle East Asia, Western Australia and Western North America are the most important dust-prone areas in the world. Along with the dust storm, salt components originated from inland saline lake and playas are often mixed with dust and transported to long distances. Dust/salt mixtures from the source of East Asian Dust Storm have great impacts on atmospheric chemistry processes and climate system due to their high hygroscopicity and efficient ice nucleation ability.

 

In this study, dust/salt mixture samples are collected from important sources of East Asian Dust Storm, i.e., Badain Jaran Desert, Tengger Desert and Ulan Buh Desert in northwestern China. Ion chromatography (IC) measurements were performed to determine the concentrations of cations (Na+, K+, Mg2+, Ca2+, and NH4+) and anions (Cl−, SO42−, NO3−, NO2−, and F−). Synchrotron-based scanning transmission X-ray microscopy (STXM) was carried out to show the morphology and chemical mapping of typical dust/salt particles. Hygroscopic properties of the samples are measured by a vapor sorption analyzer, and a thermodynamic model is used to predict the deliquescence relative humidity (DRH) based on chemical composition of the samples. To further understand the linkages between the physiochemical properties and the origins/types of the samples, we performed positive matrix factorization (PMF) receptor model to analyze the results of the IC and the DRH results. In addition, the ice nucleation abilities were conducted with the portable ice nucleation chamber II (PINCii), where both homogeneous freezing and deposition nucleation were observed on the dust/particle aerosol particles/droplets.
Response of the Wilkes Subglacial Basin Ice Sheet to Southern Ocean Warming During Late Pleistocene Interglacials 
Authors: Crotti Ilaria , Quiquet Aurélien , Landais Amaelle , Stenni Barbara , Frezzotti Massimo , Wilson David , Severi Mirko , Mulvaney Robert , Wilhelms Frank , Barbante Carlo
Published: March 2022

The growth and decay of marine ice sheets act as important controls on regional and global climate and sea level. The Wilkes Subglacial Basin ice sheet appears to have undergone thinning and ice discharge events during recent decades, but its past dynamics are still under debate. The aim of our study is to investigate ice margin retreat of the Wilkes Subglacial Basin ice sheet during late Pleistocene interglacials with the help of new high-resolution records from the TALDICE ice core. Here we present a multiproxy approach associated with modelling sensitivity experiments.

The novel high-resolution δ18O signal reveals that interglacial periods MIS 7.5 and 9.3 are characterized by a unique double-peak feature, previously observed for MIS 5.5 (Masson-Delmotte et al., 2011), that is not seen in other Antarctic ice cores. A comparison with our GRISLI modelling results indicates that the Talos Dome site has probably undergone elevation variations of 100-400 m during past interglacials, with a major ice thickness variation during MIS 9.3, likely connected to a relevant margin retreat of the Wilkes Subglacial Basin ice sheet. To validate this elevation change hypothesis, the modelling outputs are compared to the ice-rafted debris record (IBRD) and the neodymium isotope signal from the U1361A sediment core (Wilson et al., 2018), which show that during MIS 5.5 and especially MIS 9.3, the Wilkes Subglacial Basin ice sheet has been subjected to ice discharge events.

Overall, our results indicate that the interglacial double-peak δ18O signal could reflect decreases in Talos Dome site elevation during the late stages of interglacials due to Wilkes Subglacial Basin retreat events. These changes coincided with warmer Southern Ocean temperatures and elevated global mean sea level, confirming the sensitivity of the Wilkes Subglacial Basin ice sheet to ocean warming and its potential role in sea-level change.
Analysis of global and net radiation fluxes in relation to surface albedo at DACCIWA site in Ile-Ife, southwest Nigeria
Authors: Ajao Adewale , Abiye Olawale , Agboola Akeem
Published: March 2022

Measurements of global solar and net radiation fluxes were made above a grass-covered surface at DACCIWA site in a tropical location, Ile-Ife, southwest Nigeria for a period of three years (2017 - 2019). The radiation data sets were obtained from a four-component net radiometer (model NR01). Observations were made for cases of clear sky and cloudy conditions during the measurement period. The results showed considerable fluctuations of both radiation fluxes occurring during the period of measurements at the location. For clear sky conditions, the magnitudes of global and net radiation fluxes were higher than those observed for cloudy conditions due to attenuation by clouds and aerosols. For the period of observation, the highest radiation flux values occurred in 2018 while the lowest were observed in 2017. The daily surface albedo (α) values ranged from 0.16 to 0.22 at the site. Empirical relationships obtained for global solar and net radiation are  RN = 0.754 RG – 17.4 Wm-2 and  RN = 0.657 RG – 32.7 Wm-2 for wet and dry seasons respectively. Based on the empirical relationships, daily net and global solar radiation can be obtained when measurements like these are not available. Linear relationships between RN  and RG indicate that for all days (cloudy and clear sky conditions), average RN  is about 65 % of RG , and about 50 % of  RG for clear sky conditions at the location
On the impact of bio-geomorphological gradients on salt marsh survival 
Authors: Schwarz Christian
Published: March 2022

Coastal wetlands are among some of the most biologically productive ecosystems on the planet. Not only do they sequester large amounts of carbon and improve water quality, but they also provide a buffer between the ocean and coastal communities protecting them from effects of climate change such as accelerated sea level rise or increased storm frequency. Over the past century, increased salt marsh area loss was observed through the formation of internal open water bodies, so-called ponds, emerging in established wetlands such as temperate salt marshes fringing the US Mid-Atlantic coast. However, detailed causes leading to pond formation and their implications for salt marsh survival are still subject to debates. This study focused on disentangling the impact of bio-geomorphological gradients, governing sediment, and plant species composition on the formation of ponds. Marsh platforms are composed of a mosaic of plant species differing in growth properties related to tolerance in inundation stress and soil anoxia. Salt marsh sediment characteristics were shown to change with increasing distance from the open water sediment source creating specific spatial gradients. We carried out stratified field surveys on plant species distribution and sediment characteristics (e.g., organic matter content and compressibility) and compared results to a controlled mesocosm experiment identifying the plant-species growth response to differences in inundation time. The combination of field and laboratory measurements enables us to evaluate how bio-geomorphological gradients consisting of species-specific plant properties (plant growth and mortality) and sediment characteristics can explain pond formation and marsh degradation.
19F-MRI and numerical modeling as a combined method for the measurement and prediction of fluorinated substances (e.g. PFASs) transport in porous media
Authors: Fries Elisabeth , Courtier-Murias Denis , Gil Roca Jaime , Peyneau Pierre-Emmanuel , Michel Eric , Béchet Béatrice
Published: March 2022

The topic of per- and polyfluoroalkyl substances (PFASs) is a late-breaking issue due to its high environmental relevance (toxicity, persistence and bio accumulation) and due to the detection of PFASs as contaminants in various environmental compartments including groundwater, surface water and soil. PFASs enter the environment for instance through industrial, agricultural, and house-hold activities. Restricted PFASs like PFOA by the Stockholm Convention 2019 have often been replaced by molecules of the same family with shorter carbon chains, and nowadays around 4000 different molecules of PFASs can be found in the environment. Although PFASs have been manufactured since the 1940s, the fate of these chemicals in soils was not studied until the late 1990s.
These studies have shown that the retention of PFASs in soils depends on various factors such as the PFASs type (e.g. molecular structure and carbon chain length), the soil properties (e.g. amount of organic carbon), and the pore water (e.g. degree of saturation, pH). Still, the retention – and release – mechanisms of PFASs on soil constituents are not completely elucidated, and a generic model able to predict the transport of PFASs in the subsoil is not available yet.
In this work, building on a recently developed approach coupling nuclear magnetic resonance (19F - NMR) and modeling [1], we used magnetic resonance imaging (19F - MRI) to obtain quantitative information of the spatial and temporal distribution of a fluorinated substance inside a porous medium during transport experiments. We validated the performance of our approach by comparing MRI profiles obtained during flow-through experiments in sand columns tracing the transport of sodium fluoride (NaF) – a fluorinated non-reactive tracer – with traditional breakthrough curve and numerical simulations. These results pave the way for the application of this innovative MRI/modeling approach PFASs and conclusively to improve our understanding and modeling capability of PFASs fate in porous media.

[1] Courtier-Murias, D., Michel, E., Rodts, S., & Lafolie, F. (2017). Novel Experimental-Modeling Approach for Characterizing Perfluorinated Surfactants in Soils. Environmental Science and Technology, 51(5), 2602–2610. https://doi.org/10.1021/acs.est.6b05671
Study on distribution characteristics of loess gully at medium watershed scale based on UAV images
Authors: zhang chunmei , wang chunmei , yang qinke , pang guowei , yang lijuan , wang lei , long yongqing
Published: March 2022

Abstract:Gully erosion is one of the soil erosion types with the largest sediment yield on the Loess Plateau, and also an important part of soil erosion control on the Loess Plateau. Based on the UAV aerial photography as in 2020, with systematic sampling method in Chabagou watershed and select 32 small watershed as the basic research unit, artificial visual interpretation method is used to draw small watershed, gully ditch, gully and ancient valleys line, gully region of northern Shaanxi loess cutting groove distribution characteristics and influencing factors of medium watershed scale of research and analysis. The results showed that : (1) The intensity of gully erosion in chabagou Basin is middle reaches & GT; Downstream & gt; In the upper reaches of the basin, the length, number and area of ditches per unit area are 9.03 km, 339.04 and 7.29hm2, respectively. More than 50% of the ditches are between 10m and 30m in length, and 60% of the ditches are less than 150m²; (2) The ancient gully length density, gully length density, gully strip density and gully area density were the highest in the middle reaches of the basin. (3) The positive and negative terrain area ratio and slope directly affect the gully density, showing a moderate correlation; NDVI and the proportion of cultivated land had an indirect effect on the gully density, and the correlation was strong. The length, density and number of ditches in shady slope were significantly higher than those in sunny slope. This paper can explain the development characteristics of gully at medium watershed scale in loess gully region, clarify its distribution law, and provide theoretical basis for gully erosion control. 
Study of the influence of various vertical turbulent diffusion profiles on the concentrations of secondary inorganic aerosol and their gas precursors over Central Europe
Authors: Bartík Lukáš , Liaskoni Marina , Huszar Peter
Published: March 2022

Uncertainties associated with the determination of model vertical turbulent diffusion profiles are generally considered to be one of the main causes of the discrepancies between modeled and measured pollutant concentrations.  In this work, we performed four two-year long offline simulations, specifically for the period 2018–2019, using the WRF-CAMx model system over Central Europe with a horizontal resolution of 9 km x 9 km in which we used various methods of calculation of vertical turbulent diffusion coefficients (based on WRF meteorology) while the other meteorological fields we kept the same. Further, we analyzed the effects of these perturbations on spatio-temporal changes in concentrations of some components of the fine fraction of inorganic aerosols (ammonium, sulfates and nitrates) and their gaseous precursors (ammonia, NOx, sulfur dioxide). We also validated the surface concentrations of the mentioned pollutants using the AirBase and EMEP datasets.
Minimising nitrogen losses from agricultural soil using a nitrogen-doped nanocomposite
Authors: Chadwick Jessica , Zhang Peng , Lynch Iseult , Ullah Sami , Mushinski Ryan
Published: March 2022

Nitrogen emissions from agricultural soils have been increasing over the past century due to improved accessibility of nitrogen fertilisers. These fertilisers have unbalanced the global nitrogen (N) cycle, with far-reaching effects on soil acidification and biodiversity, eutrophication, and ozone depletion. The high yields achieved by modern agriculture must be maintained but this cannot come at the cost of the earth. Nanomaterials have been proposed as a viable alternative to improve conventional fertilisers and have been tested on a range of crops, with analysis of their effects on N cycling also common. Nanofertilisers have one or more dimensions on a nanoscale, and their high surface area to volume ratio causes them to adsorb to biomolecules around them, changing their reactivity and stability as they enter new environments. Previous work (Ramirez-Rodriguez et al. 2020) showed the nanocomposite, urea-doped amorphous calcium phosphate (U-ACP), was able to maintain wheat yield at a much lower concentration as compared to urea alone. Our study compared U-ACP to urea treatment on lettuce growth, N-cycle community size, N leachate concentration and reactive N-oxide (NOY) emissions. Urea and U-ACP treatment both produced more lettuce biomass than the control. However, U-ACP treatment significantly reduced NOY emissions from soil as compared to urea-treated soils, reducing emissions down to the same concentration as control soils. This pattern was also seen in aqueous emissions of reactive N species (ammonium, nitrite, and nitrate), with urea treated soils consistently producing higher concentrations than U-ACP treated soils. Denitrifying bacteria were more prevalent in U-ACP treated soils, potentially reflecting that the nanocomposite is able to aid in more complete denitrification, reducing production of intermediary, polluting N species. Our work focussed on NOY over other forms of volatile N, the high levels of NOY production by urea-treated soils indicate this may be an area of research that is deserving of greater attention in the future. This work illustrates that U-ACP, and other composite nanocarriers like it, may be good fertiliser candidates going into the future to reduce agricultural pollution, while maintaining crop yields.
Spontaneous transitions between sub- and superrotation in dry and moist shallow-water turbulence on the sphere
Authors: Schröttle Josef , Harnik Nili
Published: March 2022

We run a moist shallow water model with stochastic mesoscale forcing, to simulate the effects of mesoscale forcing on exciting large-scale flow structures. In previous work, we showed how the mesoscale forcing excites a classical -5/3 eddy kinetic energy upscale cascade to planetary scales where the linear tropical modes such as Rossby, Yanai, Intertial Gravity, and Kelvin waves form. In this work, we focus on the arising zonal mean flow.

We present results from ensembles of a few hundred simulations indicating multiple-equilibria in the tropical flow, once latent heat release passes a certain threshold in the first 1000 days. Runs up to one hundred thousand days confirm these results and show abrupt transitions in the dry and moist shallow-water turbulence lasting several thousand days. We will discuss the transient nature of the mean flow and suggest a possible new mechanism for the transition of the wind at the equator to super-rotation in a moist environment.
A unified moisture mode theory for the Madden Julian Oscillation and the Boreal Summer Intraseasonal Oscillation
Authors: Wang Shuguang , Sobel Adam
Published: March 2022

The Madden Julian Oscillation (MJO) and the Boreal Summer Intraseasonal Oscillation (BSISO) are fundamental modes of variability in the tropical atmosphere on the intraseasonal time scale. A linear model, using a moist shallow water equation set on an equatorial beta plane, is developed to provide a unified treatment of the two modes and to understand their growth and propagation over the Indian Ocean. Moisture is assumed to increase linearly with longitude and to decrease quadratically with latitude. Solutions are obtained through linear stability analysis, considering the gravest (n=1) meridional mode with nonzero meridional velocity.

Anomalies in zonal moisture advection and surface fluxes are both proportional to those in zonal wind, but of opposite sign. With observation-based estimates for both effects, the zonal advection dominates, and drives the planetary-scale instability. With a sufficiently small meridional moisture gradient, the horizontal structure exhibits oscillations with latitude and a northwestsoutheast horizontal tilt in the northern hemisphere, qualitatively resembling the observed BSISO. As the meridional moisture gradient increases, the horizontal tilt decreases and the spatial pattern transforms toward the "swallowtail" structure associated with the MJO, with cyclonic gyres in both hemispheres straddling the equatorial precipitation maximum. These results suggest that the magnitude of the meridional moisture gradient shapes the horizontal structures, leading to the transformation from the BSISO-like tilted horizontal structure to the MJO-like neutral wave structure as the meridional moisture gradient changes with the seasons. The existence and behavior of these intraseasonal modes can be understood as a consequence of phase speed matching between the equatorial mode with zero meridional velocity (analogous to the dry Kelvin wave) and a local off-equatorial component that is characterized by considering an otherwise similar system on an f-plane.
Amplification of annual and diurnal cycles of alpine lightning over the past four decades
Authors: Simon Thorsten , Mayr Georg J. , Morgenstern Deborah , Umlauf Nikolaus , Zeileis Achim
Published: March 2022

Motivation: The response of lightning to a changing climate is not fully understood. Historic trends of proxies known for fostering convective environments suggest an increase of lightning over large parts of Europe. Since lightning results from the interaction of processes on many scales, as many of these processes as possible must be considered for a comprehensive answer.

Objectives: Our aim is a probabilistic reconstruction of summer lightning over the European Eastern Alps down to its seasonally varying diurnal cycle. This necessitates consideration of many processes which becomes feasible by combining a statistical learning approach with several recent scientific achievements: Decade-long seamless lightning measurements by the Austrian Lightning Detection & Information System (ALDIS) and hourly reanalyses of atmospheric conditions including cloud micro-physics within the fifth generation ECMWF atmospheric reanalysis (ERA5).

Methods: These two data sets have been linked by the statistical learning approach called generalized additive model (GAM). GAMs are capable to identify nonlinear relationships between the target variable (lightning yes/no) and explanatory variables (ERA5). The most important explanatory variables have been selected objectively using a combination of stability selection and gradient boosting. This objective selection has reduced the pool of 85 potential ERA5 variables to the 9 most important ones. This reduced set still represents a large variety of processes including favorable environments for thunderstorms, charge separation and trigger mechanisms. The performance of the resulting GAM has been tested using cross-validation over the period of 2010-2019. 

Results: With the resulting GAM lightning for the Eastern Alps and their surroundings has been reconstructed over a period of four decades (1979-2019). The most intense changes occurred over the high Alps where lightning activity doubled in the past decade compared to the 1980s. There, the lightning season reaches a higher maximum and starts one month earlier. Diurnally, the peak is up to 50% stronger with more lightning strikes in the afternoon and evening hours. Signals along the southern and northern alpine rim are similar but weaker whereas the flatlands north of the Alps have no significant trend.
Determining latitudinal extent of energetic electron precipitation  using MEPED on-board NOAA POES
Authors: Babu Eldho Midhun , Tyssøy Hilde Nesse , Smith-Johnsen Christine , Maliniemi Ville , Salice Josephine Alessandra , Millan Robyn
Published: March 2022

Energetic Electron Precipitation (EEP) from the plasma sheet and the radiation belts ionize the polar lower thermosphere and mesosphere. EEP increase the production of NOx and HOx, which will catalytically destroy stratospheric ozone, an important element of atmospheric dynamics. Therefore, measurement of the latitudinal extent of the precipitation boundaries is important in quantifying atmospheric effects of Sun-Earth interaction.
This study uses measurements by Medium Energy Proton Electron Detector (MEPED) of six NOAA/POES and EUMETSAT/METOP satellites from 2004 to 2014 to determine the latitudinal boundaries of EEP and its variability with geomagnetic activity and solar wind drivers. Variation of the boundaries with respect to different particle energies and magnetic local time is studied. Regression analyses are applied to determine the best predictor variable based on solar wind parameters and geomagnetic indices. The highest correlation was found for pressure-corrected Dst index through linear regression. Although, the model has an error estimate of ±2.2° cgmlat and exhibits a solar cycle bias, it performs well in predicting the precipitation boundaries. The result will be a key element for constructing a model of EEP variability to be applied in atmosphere climate models.
Investigation of the Magnetospheric–Ionospheric–Lithospheric Coupling on occasion of the 14 August 2021 Haitian Earthquake
Authors: D'Angelo Giulia , Piersanti Mirko , Battiston Roberto , Bertello Igor , Cicone Antonio , Diego Piero , Follega Francesco , Iuppa Roberto , Neubuser Coralie , Papini Emanuele , Parmentier Alexandra , Recchiuti Dario , Ubertini Pietro
Published: March 2022

In the last few decades, the effort of the scientific community to clarify the issue of short-term forecasting of earthquakes has grown fast also thanks to the increasing number of data coming from networks of ground stations and satellites. This led to the discovery of several atmospheric and ionospheric anomalies statistically related to seismic activity, such as ionospheric plasma density perturbations and/or atmospheric temperature and pressure changes. With the aim to contribute in the understanding of the physical mechanisms behind the coupling between the lithosphere, lower atmosphere, ionosphere and magnetosphere during an earthquake, this paper presents a multi-instrumental analysis of a low latitude seismic event (Mw = 7.2), occurred in the Caribbean region on 14 August 2021. The earthquake happened during both super solar quiet and fair weather conditions, representing an optimal case study to the attempt of reconstructing the seismic scenario in terms of the link between lithosphere, atmosphere, ionosphere and magnetosphere. The proposed reconstruction based on ground and satellites high quality observations, suggests that the fault break generated an atmospheric gravity wave able to perturb mechanically the ionospheric plasma density, which, in turn, drove the generation of both electromagnetic waves and magnetospheric field line resonance frequency variation. The comparison between observations and the recent analytical Magnetospheric Ionospheric Lithospheric Coupling (M.I.L.C.) model confirms the activation of the lithosphere–atmosphere–ionosphere–magnetosphere chain. In addition, the observations of the China Seismo-Electromagnetic Satellite (CSES-01), which was flying over the epicentre some hours before the earthquake, confirms both the presence of electromagnetic wave activity coming from the lower ionosphere and plasma density variation consistent with the anomaly distribution of plasma density detected at ground by a chain of Global Navigation Satellite System stations located around the epicentre.