bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal forecasting of the European North West Shelf: Quantifying the persistence of the physical marine environment
Authors: Atkins Jamie , Tinker Jonathan , Graham Jennifer , Scaife Adam , Halloran Paul
Published: February 2023

The European North West shelf seas (NWS) support economic and environmental interests of several adjacent populous countries. Forecasts of physical marine variables on the NWS for upcoming months – an important decision-making timescale – would be useful for many industries. However, currently there is no operational seasonal forecasting product deemed sufficient for capturing the high variability associated with shallow, dynamic shelf waters. Here, we identify the dominant sources of seasonal predictability on the shelf and quantify the extent to which empirical persistence relationships can produce skilful seasonal forecasts of the NWS at the lowest level complexity. We find that relatively skilful forecasts of the typically well-mixed Winter and Spring seasons are achievable via persistence methods at a one-month lead time. In addition, incorporating observed climate modes of variability, such as the North Atlantic Oscillation (NAO), can significantly boost persistence for some locations and seasons, but this is dependent on the strength of the climate mode index. However, even where high persistence skill is demonstrated, there are sizeable regions exhibiting poor predictability and skilful persistence forecasts are typically limited to ≈ one-month lead times. Summer and Autumn forecasts are generally less skilful owing largely to the effects of seasonal stratification which emphasises the influence of atmospheric variability on sea surface conditions. As such, we also begin incorporating knowledge of future atmospheric conditions to forecasting strategies. We assess the ability of an existing global coupled ocean-atmosphere seasonal forecasting system to exceed persistence skill and highlight areas where additional downscaling efforts may be needed.
Land to water phosphorus transfer processes under climate change
Authors: Mellander Per-Erik , Hawtree Daniel , Ezzati Golnaz , Murphy Conor , Galloway Jason , Jackson-Blake Leah , Norling Magnus , Jordan Phil , Pulley Simon , Collins Adrian
Published: February 2023

Water quality in European rivers is degraded by nutrient loss to waters, and such problems can be exacerbated by climate change. Climate smart mitigation measures are needed and these require insight into the underlying processes of nutrient loss under future weather conditions. To address this, the aim of this study was to assess how a changing climate may alter phosphorus (P) mobilisation, delivery and impact in two hydrologically contrasting agricultural river catchments (ca 11 km2) in Ireland. As part of the WaterFutures project and the Agricultural Catchments Programme, The Simply P model was calibrated with 10 years of high frequency data of hydro-chemo-metrics for the two catchments. Five downscaled Global Climate Models (CNRM-CM5, EC-EARTH, HadGEM2-ES, MIROC5 and MPI-ESM-LR) were used to simulate two far-future climate scenarios, one intermediate emission pathway (RCP4.5) and one intensive emission pathway (RCP8.5). The scenarios were used to estimate P concentrations and loads for the coming century. A newly developed P Mobilisation index (ratios of concentration percentiles) and P Delivery index (ratios of mass load percentiles) was used to assess changes in P transfer for the modelled P concentrations and P loads.In a hydrological flashy catchment, it was estimated that climate change alone may increase mean annual total P (TP) concentration from 0.120 mg/L monitored between 2010-2019 to 0.184 mg/L by 2070-2100. A corresponding increase in Delivery index by around 25% and 40% (for RCP4.5 and RCP8.5, respectively) but no change in Mobilisation index suggests that the impact is mostly due to enhanced hydrological connection and/or reduced P retention. The mean annual total reactive P (TRP) concentration was estimated to show minor decreases from 0.079 mg/L to 0.075 mg/L. A corresponding decrease in the Mobilisation index by around 5% and 10% (for RCP4.5 and RCP8.5, respectively) but an increase in Delivery index by 25% and 40% suggests a possible decrease in soil P detachment and/or solubilisation, limiting the increased delivery potential. The same analysis on data from a groundwater-fed catchment suggests that climate induced changes in TP and TRP concentrations were mostly related to delivery processes for TP. The underlying processes for P losses associated with climate change are likely to be different for TP and TRP and for catchments with different hydrological controls. Such information helps to target more resilient land use mitigation methods and further design these for scenarios of future weather conditions and land use.
The attribution of flash flooding impacts over cities in the United Kingdom
Authors: Cotterill Daniel , Mitchell Dann , Stott Peter , Bates Paul
Published: February 2023

The risk of flash flooding is likely to increase with the intensification of short-duration rainfall extremes due to Climate Change. Using the latest convective-permitting resolution climate model data for the UK and the LISFLOOD-FP flood inundation model, we adopt a trend detection approach to attribute flash flooding impacts over the UK city, Leeds. Our study is based on an extreme rainfall event in August 2014, where over 400 properties were flooded after 80mm of rainfall fell in five hours in parts of the city. This research will be the first attribution study for UK pluvial flood impacts, using pure convective-permitting resolution climate model data.  The flood inundation model simulates flood maps for over 12 000 events using soil moisture and rainfall data as inputs.
Self-lofting and dynamical confinement of the Raikoke volcanic plume
Authors: Khaykin Sergey , de Laat A.T. Jos , Godin-Beekmann Sophie , Hauchecorne Alain , Ratynski Mathieu
Published: February 2023

Recent research has provided evidence of the self-lofting capacity of smoke aerosols in the stratosphere and their self-confinement by persistent anticyclones (Smoke-Charged Vortices, SCV), prolonging the atmospheric residence time and radiative effects of wildfire emissions. By contrast, the volcanic aerosols - composed mostly of non-absorptive sulphuric acid droplets – were never reported to be subject of dynamical confinement. In this study, we use high-resolution satellite observations from various satellite instruments (TROPOMI, ALADIN, CALIPSO, OMPS-LP and EUMETSAT GNSS-RO) together with high-resolution ECMWF ERA5 reanalysis and meteorological radiosoundings to show that the eruption of Raikoke volcano in June 2019 produced a long-lived stratospheric anticyclone termed Vorticized Volcanic Plume (VVP). The primary VVP structure contained 24% of the total erupted mass of sulphur dioxide, circumnavigated the globe three times, and ascended diabatically by more than 13 km in three months through radiative heating of the confined aerosol plume. We argue that persistent anticyclonic formations act to maintain the volcanic plumes at high concentration thereby providing a high degree of radiative heating and upward thrust to volcanic plumes.The mechanism of dynamical confinement has important implications for the planetary-scale transport of volcanic emissions, their stratospheric residence time, and atmospheric radiation balance. It also provides a challenge or “out of sample test” for weather and climate models that should be capable of reproducing such dynamical structures.
Estimation of the Moho depth in the Bay of Bengal using gravity data and understanding of its tectonic implications
Authors: Pathak Priyank , Kumar Mohanty William , Kumar Prakash
Published: February 2023

At the beginning of the Cretaceous period, India and Antarctica started breaking apart. There were major changes to the seafloor in the Bay of Bengal (BOB) and geodynamic processes after this episode. Therefore, it is interesting to detailed understanding of the tectonics of the BOB. The BOB is surrounded by Bangladesh to the north, the Andaman-Sumatra arc to the east, and the eastern coast of India to the west. Bouguer gravity anomaly, elevation, and sediment thickness data are used in this study to determine the gravity Moho and Isostatic Moho topography of the BOB. The gravity effects of sediments are calculated by using the recent GlobSed model. Gravity Moho is derived from the inversion of sediments corrected gravity data using the Parker‐Oldenburg method. Generally, it is observed that the thin crust is associated with the BOB while the thicker crust is associated with two aseismic ridges: Ninetyeast and 85°E ridges, situated in the eastern and central parts of BOB, respectively. This suggests that these ridges may have formed due to the interaction of the plume-spreading centre. The thick depressed crust beneath the northernmost part of BOB, implies that it is due to a load of sediments, and abrupt ~12 km deepening of gravity Moho from eastern BOB (Sumatra trench) to Andaman Arc. The consequences of the difference between gravity and isostatic Moho for the isostatic state of the crust are examined in order to understand the geodynamics of the study area. The isostatic analysis of crust, which takes into account the difference between the two types of Moho, shows that all of the regions except for the north of Bengal fan, Ninetyeast ridge, and southern region of 85°E ridge are compensated. The Moho of the Andaman Arc and the north of Bengal fan, are overcompensated, which should be uplifted, while the Moho of the Sumatra trench, Ninetyeast ridge, and the southern region of 85°E ridge become depressed. In order to make isostatic compensation of the region, an additional upper mantle density variation between 47 to 62 kg/m3 has to be added. This implies an additional compensation mass is needed under the Ninetyeast ridge and the southern region of 85°E ridge is 47 kg/m3 and 56 kg/m3, respectively, for providing isostatic equilibrium.
Sentinel-1 data monitoring Land Subsidence and Groundwater dynamics in the populous cities of Rajasthan, India
Authors: Dhayal Pooja , Ojha Chandrakanta
Published: February 2023

In India, around 80% of the population uses groundwater (GW) for their basic needs, out of which more than 60% are for agricultural activities and 85% for drinking water usage(H Kulkarni et al. 2015). The continuous depletion of groundwater levels(GWL) is becoming a significant concern in many agrarian regions of northwest India such as Delhi, Punjab and Rajasthan.This study focused on a few metropolitans and historical cities of Rajasthan, mainly in Sikar, Jaipur, and Jodhpur districts, where the Central Groundwater Board (CGWB) report shows groundwater depletion has been significant over the last two decades. The study areas in the eastern and western parts of Rajasthan are most susceptible to frequent droughts and dense populations and have much less than the average national rainfall.This research consists of twofold objectives to investigate the groundwater dynamics of the aquifer systems in those regions. First, we focus on understanding GW situations over the study areas using rainfall and suitable water-level data. Second, we investigate local scale surface deformation maps exploring Sentinel-1(S1) data of the European Space Agency (ESA) using an advanced multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique. From 2000 to 2021,the precipitation data over Sikar, Jaipur, and Jodhpur districts show an average rainfall of 519.1 mm, 572.6 mm, and 337.81 mm, respectively, which are less than India’s national average, that is 1180 mm. Further, we analyzed 21 years of CGWB’s GW-level data from 2000 to 2021 over the three districts. We noticed a declining trend in water levels for all three regions during the study periods. The head-level data in Jaipur, such as Harmara, Astikalan, and Bhankrota, illustrate average GWL of 83.9 m, 71.59 m, and 70.35 m, respectively. In the Sikar district, Dhod, Ghana, and Rashidpura wellstations display an average GWL of 76.59 m, 69.3 m, and 83.1 m, respectively. In Jodhpur district, GWstations like Balarwa, Kapuria, and Khara have an average GWL of 116.13m, 77.31m, and 104.2 m, respectively. Analyzing further the local scale land motion, firstly, we carried out InSAR processing over the Sikar District, where 132 SAR acquisition of S1 with P34 descending orbital track considered from Sep 2016 to Dec 2021. We followed the Small BAseline Subset (SBAS) technique using the GMTSAR-InSAR tool by Sandell et al., 2011 for our data processing. The results exhibit 50 or 60 mm of land subsidence in the western and central parts of the Sikar district, whose displacement time series correlates well with the head-level decline. However, the ongoing investigation is being carried out by processing the S1 descending data from 2016 to 2021 over the Jaipur and Jodhpur districts and correlating InSAR results with the water-level change to understand the response of aquifer systems.
The importance of internal climate variability in the multi-decadal trend of the wind-driven upwelling on the west African coasts
Authors: Bordbar Mohammad Hadi , Mohrholz Volker , Schmidt Martin
Published: February 2023

Like other Eastern Boundary Upwelling Systems, the upwelling near the southwest African coasts is primarily alongshore-wind-driven, whereas it is controlled mainly by the wind stress curl farther offshore. The surface wind regime across the Benguela Upwelling System (BUS) is strongly related to the South Atlantic Anticyclone (SAA), which is believed to migrate poleward in response to anthropogenic global warming. Here, we investigate multi-decadal changes of the SAA and its impacts on the coastal Ekman transport as a primary driver of coastal upwelling and the wind-stress-curl-driven upwelling across the BUS by using the ERA-5 data sets. Our findings indicate that the SAA plays a significant role in the regional wind-driven upwelling with different impacts on the coastal Ekman transport and the offshore wind-stress-curl-driven upwelling. Further, the upwelling in the equatorward sector is significantly affected by the anticyclone intensity. In contrast, the poleward portion is also influenced by the meridional position of the anticyclone. The multi-decadal trend in the sea level pressure across the South Atlantic renders a considerable heterogeneity in space. However, the trend is broadly associated with a small signal-to-noise ratio, which can be attributed to internal climate variability. This view is further supported by the multi-decadal trend in coastal offshore transport and the wind-stress-curl-driven upwelling in multiple upwelling cells, which hardly depict any significant systematic changes.
Projected changes in the distribution of global Mediterranean climate-type regions
Authors: Zittis George , Urdiales-Flores Diego , Cherchi Annalisa , Hadjinicolaou Panos
Published: February 2023

Mediterranean climate-type regions are characterized by warm-to-hot dry summers and mild, wet winters (Csa and Csb categories in Köppen classification). These regions are especially vulnerable to climate change since temperature and precipitation are expected to change in opposite directions. Impacts of extreme events (e.g., severe heat waves and prolonged droughts), challenges in water availability and food security, as well as other aspects of human livelihood, require a detailed global view of future changes in these unique mid-latitude zones.Here, we explore the observed trends and future distribution of global Mediterranean climate-type regions (MCR). We analyze gridded observations and a bias-adjusted and statistically downscaled dataset of five global Earth System Models from Coupled Model Intercomparison Project phase 6 (CMIP6). For supporting decision-making and climate mitigation efforts, we focus on different global warming levels (e.g., 1.5, 2, 3, and 4°C) derived from the Shared Socioeconomic Pathway SSP5-8.5.Our preliminary results show that for the rest of the 21st century, the CMIP6 models project that the total MCR area will not change significantly. However, our analysis highlights a robust poleward and eastward expansion of Csa zones at the expense of cooler climates (incl. Csb) over three regions, corresponding to a 21% increase in their area in the Mediterranean Basin, a 41% increase in North America-California, and 12.2% increase in South America-Central Chile. For every one additional degree of global warming, mean rainfall will likely decrease by about 4-5 % in most of the Mediterranean Basin, Southern Africa, and Southern Australia, while in South America-Central Chile, this decrease is more pronounced (near 10%). On the contrary, for every degree of global warming, mean rainfall will likely increase by about 5% in North America-California.
The concentration of cosmogenic radionuclide 7Be from the perspective of space weather and long-term trends in the stratospheric temperature and wind
Authors: Podolská Kateřina , Kozubek Michal , Hýža Miroslav , Šindelářová Tereza
Published: February 2023

Cosmogenic radionuclide Beryllium 7Be concentration is primarily determined by the solar activity level and space weather conditions. The 7Be is generated by cosmic ray reactions in the stratosphere and in the upper troposphere, binds to atmospheric aerosols and is transported horizontally and vertically by wind and gravity. The highest values of cosmic radiation are observed during the solar minima because, at that time the penetrability of the Earth’s and Sun magnetosphere is greatest.The concentrations of the radionuclide 7Be are reliable indicators of various atmospheric processes. In our work, we try to contribute to better understanding of the dynamics of processes by associating them with long-term trends of stratospheric temperature dynamics. We investigate the coupling of concentrations of the cosmogenic radionuclide 7Be in the longitudinal view during the years 1986–2022 (time series of activity concentration of 7Be in aerosols evaluated by the corresponding activity in aerosols on a weekly basis at the National Radiation Protection Institute Monitoring Section in Prague) to space weather parameters (Kp planetary index, disturbance storm time Dst, proton density, proton flux), and stratospheric dynamics parameters (temperature, zonal component of wind, O3). On short timescales the intensity of cosmic radiation decreases by few percent in several days. On a longer timescale the intensity of galactic cosmic rays is strongly influenced by the degree of solar activity and by variations in the geomagnetic field. This corresponds with findings that the zonal wind climatology differences were largest in the decades of 2000–2010 than between others observed decades.
Unbalanced emission reductions of different species and sectors in China during COVID-19 lockdown derived by multi-species surface observation assimilation
Authors: Kong Lei , Tang Xiao , Zhu Jiang , Wang Zifa , Sun Yele , Fu Pingqing , Gao Meng , Wu Huangjian , Li Jie , Pan Xiaole , Wu Lin , Akimoto Hajime , Carmichael Gregory R.
Published: February 2023

The unprecedented lockdown of human activities during the COVID-19 pandemic have significantly influenced the social life in China. However, understanding of the impact of this unique event on the emissions of different species is still insufficient, prohibiting the proper assessment of the environmental impacts of COVID-19 restrictions. Here we developed a multi-air pollutant inversion system to simultaneously estimate the emissions of NOx, SO2, CO, PM2.5 and PM10 in China during COVID-19 restrictions with high temporal (daily) and horizontal (15km) resolutions. Subsequently, contributions of emission changes versus meteorology variations during COVID-19 lockdown were separated and quantified. The results demonstrated that the inversion system effectively reproduced the actual emission variations of multi-air pollutants in China during different periods of COVID-19 lockdown, which indicate that the lockdown is largely a nationwide road traffic control measurement with NOx emissions decreased substantially by ~40%. However, emissions of other air pollutants were found only decreased by ~10%, both because power generation and heavy industrial processes were not halted during lockdown, and residential activities may actually have increased due to the stay-at-home orders. Consequently, although obvious reductions of PM2.5 concentrations occurred over North China Plain (NCP) during lockdown period, the emission change only accounted for 8.6% of PM2.5 reductions, and even led to substantial increases of O3. The meteorological variation instead dominated the changes in PM2.5 concentrations over NCP, which contributed 90% of the PM2.5 reductions over most parts of NCP region. Meanwhile, our results also suggest that the local stagnant meteorological conditions together with inefficient reductions in PM2.5 emissions were the main drivers of the unexpected COVID-19 haze in Beijing. These results highlighted that traffic control as a separate pollution control measure has limited effects on the coordinated control of O3 and PM2.5 concentrations under current complex air pollution conditions in China. More comprehensive and balanced regulations for multiple precursors from different sectors are required to address O3 and PM2.5 pollution in China.
Tracking magma plumbing system overpressure and volume through macroscopic seismic source parameters of repetitive volcanic-seismic events
Authors: Niu Jieming , Song Teh-Ru Alex
Published: February 2023

Microscopic dynamic processes associated with gas-liquid and fluid-solid interaction, as well as the magma/host-rock rheology and tectonic stress, determines the stability of magmatic/hydrothermal system underneath active volcanoes. Specifically, the overpressure in the system largely dictates the timing of upcoming eruptions, whereas the system volume controls the potential magnitude and impact of upcoming eruptions. While quantitative assessment of the system overpressure and volume provides invaluable insights into magma dynamics, eruption forecasting, and hazard mitigation, it is not trivial to constrain these fundamentals.
We devise a generic framework to estimate system overpressure and volume associated with repetitive volcano-seismic events such as VLP and LP.  Following the framework developed by Nishimura (1998), we derive the relationship between macroscopic seismic source parameters (i.e., seismic moment rate and single force), the acoustic properties of the fluid near the seismic source (i.e., sound speed and density), and system overpressure and volume. Macroscopic seismic source parameters can be obtained through waveform modeling and inversion. On the other hand, the acoustic properties of the fluid near the seismic source can be estimated by modeling the VLP/LP resonance peaks (i.e., resonance period and attenuation). Alternatively, the gas fraction obtained from the gas emission (rate) and magma output (rate), as well as local volcanic activities (e.g., hydrothermal or magmatic) could also help evaluate the fluid properties in the context of a variety of mixtures of gas, liquid and solid (e.g., Kumagai & Chouet, 2000).
As a proof of concept, we apply the newly developed framework in Aso volcano where repetitive VLP has been observed since 1930s. We show that the estimated overpressures associated with VLP during the 2014-2016 eruption cycle is on the order of ~1 MPa, generally consistent with the tensional rock strength. The size of pressurized system volume is on the order of ~106 m3, like the magmatic output in the same episode. In this report, after discussing the impact of various assumptions on the estimate of the system overpressure and volume, we will explore a global database to evaluate the system overpressure and volume and discuss relevant microscopic processes that are consistent with these findings. 
Representing Northern High Latitude Peat Fires in the JULES-INFERNO Fire Model
Authors: Blackford Katie , Voulgarakis Apostolos , Prentice Colin , Burton Chantelle , Kasoar Matthew
Published: February 2023

Anthropogenic activities and climate change are increasing the vulnerability of carbon rich peatlands to wildfires. Peat fires, which are dominated by smouldering combustion, are some of the largest and most persistent wildfires on Earth. Across the northern high latitudes, peat fires have the potential to release vast amounts of long term stored carbon and other greenhouse gases and aerosols. Consequently, peat fires can have huge implications on the carbon cycle and result in a positive feedback effect on the climate system. Peat fires also impact air quality and can lead to haze events, with major impacts on human health. Despite the importance of peat fires they are currently not represented in most fire models, leading to large underestimations of burnt area and carbon emissions in the high latitudes. Here, I present a representation of peat fires in the JULES-INFERNO fire model (INFERNO-peat). INFERNO-peat improves the representation of burnt area across the high latitudes, with notable areas of improvement in Canada and Siberia. INFERNO-peat also highlights a large amount of interannual variability in carbon emissions from peat fires. The inclusion of peat fires into JULES-INFERNO demonstrates the importance of representing peat fires in models, and not doing so may heavily restrict our ability to model present and future fires and their impacts across the northern high latitudes.
Tracing the golden tide outbreak in the Yellow Sea and East China Sea over a 15-year period using multi-satellite sensor data
Authors: Son Young Baek , Choi Jong-Kuk
Published: February 2023

The Yellow Sea (YS) and East China Sea (ECS) have the world’s largest supply of floating algae. The golden tides (Sargassum horneri) appear mainly in the YS and ECS, but become entangled as they drift. The floating harmful macroalgae blooms (HMBs) obstructs navigation and is a huge socioeconomic problem in the vicinity of coastal areas. To determine the origin and movement trend of the golden tide in the YS and ECS, the multi-satellite sensor data (e.g. Sentinel-2 and GOCI) was used to detect the floating macroalgae which was determined by the Alternative Floating Algae Index (AFAI, Wang and Hu, 2016) and mapped over the study area using a 15-year data. The occurrence period of the golden tide from 2008 to 2019 determined that they were found between January and March in the China coast, and the patches of floating macroalgae in Jeju Island and the west coast of Korea were observed between March and May. The macroalgae was detached from the waters near the Yangtze River and Zhejiang Province, China and then floating into the east and north-east ward influenced by the Tsushima warm current or Kuroshio. The build-up of the gold tide was occurred in the middle of the ECS and pile-up of them was in the coast of Korea from March to May. Recently, changes have begun to appear in movement trend of the golden tide. During 2020 and 2021, the golden tide was found in the western coast of Korea on January and in the northern waters of Jeju Island, Korea on February, and at the same time, another large-scale patch was found in the waters near the mouth of the Yangtze River and Zhejiang Province, China. From the results, the golden tide outbreak occurred that first flowed in west coast of Korea and northern Jeju Island in the winter, and then another outbreak occurred in southern Jeju Island in spring. It was analyzed that the movement trend of the golden tide has changed in recent years that the golden tide presented in the YS and ECS have different origins such as Bohai Bay and near the Yangtze River and Zhejiang Province, China.
A new python tool for coastal bathymetry estimation : S2Shores
Authors: Thoumyre Grégoire , Bergsma Erwin , Almar Rafael , Giros Alain , Lemai-Chenevier Solange , Artigues Stéphanie , Garlan Thierry
Published: February 2023

        Coastal areas host 53% of the world's population increasingly subject to risks related to climate change. In order to understand and prevent these risks, the prediction of coastal hydrodynamic and morphological evolution is essential. Bathymetry is a key geophysical variable in  A key parameter to improve numerical coastal hydrodynamics models is the bathymetry. High resolution satellites now allow to observe coastal areas at a regional to global scale in a most cost-efficient way rather than local traditional echo sounding bathymetry measurements. We present S2Shores (Satellite to Shores), a new state-of-the-art python library developed to estimate wave field characteristics such as wavelength, period, direction, celerity to derive bathymetry from satellites. The core code is optimized to process optical satellite imagery, moreover the library is built in an object-oriented structure allowing efficient and agile manipulation of the modules developed from input and output handling to post-precessing.  S2Shores is optimized, using parallel computing with Dask python library, to compute large spatial scale, or time series evolution bathymetry as well on HPC cluster as on local computer. For example a bathymetry of 4400 km² of ocean, around the French Gironde estuary, can be computed in 90 sec (using 30 cores and 9.5 Go memory usage) with a 500 meters output grid resolution. We present a work in progress new python library for bathymetry estimation that will be open to the public to use and propose collaborative improvements.
A New Weighted Modularity-Based Approach for DMA Demarcation in Large and Complex Water Distribution Networks
Authors: Pandey Jyotsna , Srinivas Venkata Vemavarapu
Published: February 2023

Water distribution networks (WDNs) need restructuring/sectorization into District Metered Areas (DMAs) depicting smaller communities for ease in ensuring equitable water distribution and pressure management. DMA demarcation also helps in systems operation and management, apart from leak and contaminant localization. Many different strategies for DMA demarcation are in use, as none is established to be universally superior. Hence, there is ambiguity in the choice of a strategy for DMA demarcation. A WDN can be viewed as a complex network due to strong interconnections among its components and imposed limitations (being a 2D network). Against this backdrop, the recent decade witnessed the use of community detection approaches from complex network theory (CNT) for DMA demarcation. Community detection is a very basic yet pivotal task in the field of CNT. Modularity maximization is the most widely used approach for community detection. The modularity index defines the quality of the subgraphs or communities delineated from a network. In the case of a WDN, some nodes may be shared by more than one DMA, in which case the conventional and existing variants of the modularity index cannot be used for assessing the quality of the delineated DMAs. A more comprehensive community (DMA) detection procedure must incorporate such nodes with multiple associations among communities. Facilitating this, the present study proposes a comprehensive approach for DMA demarcation in large and complex WDNs considering a weighted modularity index. Edge weights are assigned to incorporate the hydraulic behaviour of a network and the association of nodes among various communities. The efficacy of the proposed approach vis-à-vis existing methods is demonstrated through a case study on a benchmark WDN. Effective demarcation of DMAs helps in their prioritization (based on the existing network level measures) to devise mitigation strategies for improving their performance.
Dynamics and scaling of moist, internally cooled convection
Authors: Agasthya Lokahith , Muller Caroline Jane
Published: February 2023

Idealised models of convection such as Rayleigh-Bénard convection, horizontal convection etc. have been widely used to study the behaviour of natural fluid systems including but not limited to the atmosphere, the oceans and the flow of lava in the earth's core in a simplified setting 1,2. While such idealised models include only a small subset of the physical processes occurring in nature, their simplified dynamics allows for easier interpretation and study of the interactions of individual physical processes. In this numerical study, we consider the case of an idealised moist convecting thermal system, with various Dirichlet and Neumann boundary conditions for the temperature and water vapour mixing ratio. The model includes a vertical temperature lapse-rate, the release of latent heat due to the condensation of water vapour and a constant bulk-cooling term to simulate moist convection accompanied by radiative cooling in the earth's atmosphere. This study follows previous studies which have used similar idealised scenarios to understand dry 3 as well as as moist 4 atmospheric convection. The model is studied for its dynamical response and scaling for varying boundary conditions and input parameters such as the strength of the radiative cooling, the steepness of the lapse rate and the latent heat of condensation to better understand the interaction between moist convection and radiative cooling in the atmosphere. We also compare the convective organisation in our simplified model with more complex cloud-resolving atmospheric simulations 5. References:1. G. Ahlers, S. Grossmann, and D. Lohse, “Heat transfer and large scale dynamics in turbulent Rayleigh-Bénard convection,” Reviews of modern physics, vol. 81, no. 2, p. 503, 2009.2. G. O. Hughes and R. W. Griffiths, “Horizontal convection,” Annu. Rev. Fluid Mech., vol. 40, pp. 185–208, 2008.3. M. Berlengiero, K. Emanuel, J. Von Hardenberg, A. Provenzale, and E. Spiegel, “Internally cooled convection: a fillip for philip,” Communications in Nonlinear Science and Numerical Simulation, vol. 17, no. 5, pp. 1998–2007, 20124. G. K. Vallis, D. J. Parker, and S. M. Tobias, “A simple system for moist convection: the rainy–bénard model,” Journal of Fluid Mechanics, vol. 862, pp. 162–199, 20195. C. J. Muller and I. M. Held, “Detailed investigation of the self-aggregation of convection in cloud-resolving simulations,” Journal of the Atmospheric Sciences, vol. 69, no. 8, pp. 2551– 2565, 2012.Acknowledgement - This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 101034413.
Analyses of thunderstorm structures using data of a Ka-band Doppler polarimetric vertical cloud profiler
Authors: Sokol Zbyněk , Popová Jana , Skripniková Kateřina
Published: February 2023

This study investigates the structure of strong convective storms to determine the difference between the structure of storms inducing or not lightning discharges. The structure of strong convective storms is investigated using a Ka-band Doppler polarimetric vertical cloud profiler operating at a frequency of 35 GHz. The profiler is located at the Milešovka meteorological observatory in Czechia (Central Europe). To study the structure of storms, we used the basic radar measurements of phase and power spectra of the co- and the cross-channel. We analysed the data from all the storms that occurred close to the Milešovka observatory during 2018-2022 and we performed statistical and correlation analyses of vertical profiles of phase and power spectra in the co- and the cross-channel in dependence on the distance of lightning discharges observed and recorded by the EUCLID lightning network.
Soft X-ray Imaging of Earth’s Magnetopause under Different Solar Wind Conditions: Three-Dimensional Global Hybrid Simulations
Authors: Guo Jin , Sun Tianran , Lu San , Lu Quanming , Lin Yu , Wang Xueyi , Huang Kai , Wang Rongsheng
Published: February 2023

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas, and it is also the boundary of the solar wind energy transport to the magnetosphere. Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional (2-D) global view from a satellite. However, it is challenging to derive information about the three-dimensional (3-D) magnetopause from a 2-D X-ray image. By performing 3-D global hybrid simulations, we obtain the soft X-ray imaging of Earth’s magnetopause under different solar wind conditions. The soft X-ray images observed by a hypothetical satellite are shown, and the location of the magnetopause, the cusps, and the magnetosheath are all identified in the X-ray images. Although there is a large amplitude fluctuation of the X-ray emissivity in the magnetosheath, the maximum X-ray intensity matches the tangent directions of the magnetopause well, which indicates that the magnetopause location can be identified from the 2-D X-ray images. Moreover, the magnetopause location can be identified with different positions of the satellite. We also find that solar wind conditions have little effect on the magnetopause identification. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will provide the X-ray images of the magnetopause for the first time, and our global hybrid simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective, with particle kinetic effects considered. 
Twenty years of radar data from a single C-band radar - Potentials and drawbacks in rainfall statistics
Authors: Thorndahl Søren , Andersen Christoffer Bang
Published: February 2023

In terms of spatial and temporal information, weather radar data offers notable advantages when used for rainfall statistics compared to rain gauge records. In the past, long-term statistics were only possible through the use of rain gauge records. However, the availability of more than one decade of radar data now allows for a more detailed analysis of rainfall variability in both space and time.For radar-based statistical analyses to be a reliable alternative to rain gauge statistics, it is essential to have high-quality, consistent data that is free of errors. While advancements in technology, such as dual polarimetric estimation, have improved our ability to quantify rainfall intensities with radar, it is still necessary to utilize "ground truth" records from rain gauges to adjust and ensure the accuracy of the radar estimates. In extreme value statistics where long-term continuous records are required, it is necessary to not only utilize the latest technology but also to adjust and verify older data (e.g. pre dual-pol. data or data with lower spatial and temporal resolution)This abstract present data from a 20-year radar series single radar from Denmark, where several analyses with regard to rainfall statistics have been conducted. We describe and quantify challenges in bias adjustment, advection interpolation to improve temporal resolution, duration-dependent biases, spatial scaling issues comparing points and pixels, subpixel variability, range dependence in rainfall estimates, etc.We apply the data to develop extreme value statistics based on peak-over-threshold ranking and stochastic storm transposition. Furthermore, we examine spatial variability using radar-based areal reduction factors as well as spatial correlation analyses and severity diagrams. The analyses and application of radar data are conducted with an aim towards application in urban hydrology.
Climatological analysis of warm conveyor belt contributions to UTLS moisture content
Authors: Guo Ziyan , Schwenk Cornelis , Boettcher Maxi , Brast Nils , Reutter Philip , Miltenberger Annette
Published: February 2023

The Upper Troposphere-Lower Stratosphere (UTLS) is a transition region for coupled dynamical, chemical and microphysical processes. These coupled processes play an essential role in climate change. Water vapor, ozone and aerosols in the UTLS region have important impacts on the Earth’s radiation budget. Systematic biases in UTLS moisture are known to exist in global climate models. Understanding the sources of UTLS moisture and quantifying the transport processes that control water vapor and clouds in the UTLS can provide important insights into the model uncertainties and improve model simulations. In the extratropics ascending airstreams in extratropical cyclones, particularly the warm conveyor belt (WCB), and deep convection are thought to be the most important sources of UTLS moisture. Here, we utilize ERA5 reanalysis data and IAGOS aircraft measurements to quantify the contribution of WCBs to UTLS moisture for the decade 2010 to 2019. WCB outflow regions are defined using Lagrangian trajectories. The moisture anomaly in the WCB outflow compared to average UTLS moisture content is quantified as well as its evolution over the 2 days after WCB ascent. ERA5 suggests significant positive moisture anomalies in the WCB outflow that persists over several days. Finally, ERA5 UTLS moisture content is compared to IAGOS humidity measurements with a particular focus on WCB outflow regions. In summary, we present a comprehensive climatological picture of the role of WCB moisture transport for the UTLS composition.
Lithospheric sill intrusions and present-day ground deformation at Rhenish Massif, Central Europe
Authors: Silverii Francesca , Mantiloni Lorenzo , Rivalta Eleonora , Dahm Torsten
Published: February 2023

The Rhenish Massif in Central Europe, which includes the Eifel Volcanic Fields, has shown ongoing ground deformation and signs of possible magmatic activity. A buoyant plume with distributed partial melts exerting uplift forces at the bottom of the lithosphere has been proposed to explain the current deformation; the hypothesis that melt is accumulating in the crust or lithospheric mantle has not been explored yet. Here, we test deformation models in an elastic half space considering sources of varying aspect ratio, size and depth. We explore the effects of data coverage, noise and uncertainty on the inferred source parameters. We find that melt accumulation within the lithosphere cannot be ruled out if this emplacement occurs in sub-horizontal structures expanding at the rate of 0.045 km^3/yr. We discuss our results in the context of plume and underplating models worldwide and elaborate on what further observations may be needed to better constrain the structure of the Eifel magmatic system.
Rhizosphere priming in a warming Arctic: Are peatlands insusceptible?
Authors: Wild Birgit , Monteux Sylvain , Wendler Bernd , Hugelius Gustaf , Keuper Frida
Published: February 2023

Rapid warming is currently accelerating Arctic carbon cycling, including increased permafrost thaw and CO2 production from soil organic matter decomposition, but also CO2 uptake by plants. Plants can additionally stimulate soil organic matter decomposition near their roots, via the rhizosphere priming effect. In a recent modeling study, we showed that priming can accelerate Arctic soil carbon loss at a globally relevant rate, and spatial analysis pointed to large potential contributions from carbon-rich permafrost peatlands. At the same time, the high carbon content of peatlands might render them insusceptible to input of easily available organic compounds by plant roots, which is considered a key component of priming. We here investigated the susceptibility of permafrost peat soils to priming by plant compounds under aerobic conditions that resemble the dominant rooting zone. To that end, we combined a 30-week laboratory incubation of peat soils from five circum-Arctic locations, with a literature meta-analysis of priming studies of Arctic peat and mineral soils. The combined experimental and literature data showed substantially and significantly weaker priming susceptibility of peat than mineral soils. Organic carbon addition increased CO2 production from soil organic matter in mineral, but not in peat soils. Organic nitrogen addition had a significant effect on both sample types, but that of peat was much weaker. These observations point at fundamental, mechanistic differences in the response of peat and mineral soil organic matter decomposition to changing carbon and nitrogen availability. In a new model sensitivity analysis, we show that insusceptibility of peatlands to priming would substantially reduce estimates of priming-induced carbon loss from the circum-Arctic. While our study suggests a limited effect of plant-released organic compounds on peat decomposition, it does not preclude a vegetation effect on decomposition under natural conditions. The large carbon stocks of circum-Arctic peatlands and expected changes in vegetation and drainage, call for increased efforts to quantify the combined effect of living plants on soil processes beyond carbon input.
Navier–Stokes equations in Fractional Time and Multi‑Fractional Space
Authors: Ercan Ali , Kavvas M. Levent
Published: February 2023

This presentation focuses on the governing equations of incompressible and compressible flow in fractional time and multi-fractional space as developed recently by the authors in DOI: 10.1038/s41598-022-20911-3. Mathematical differentiation has found many applications in real-life problems in the last two decades, before which it was mainly utilized by mathematicians and theoretical physicists. The proposed fractional governing equations for fluid flow may be interpreted as the general forms of the classical Navier–Stokes equations; as they reduce to the classical ones when integer values are replaced with their fractional powers in space and time. Due to their nonlocal structure, proposed governing equations in factional time/space can reflect the initial conditions for long times, and the boundary conditions for long distances. Results of numerical applications are presented for flow due to a wall suddenly set into motion. It is found that the proposed equations have the potential to model both sub-diffusive and super-diffusive flow cases.
Satellite and terrestrial spherical harmonic coefficients of the external gravitational potential do not match
Authors: Bucha Blazej , Sanso Fernando
Published: February 2023

In geodesy, the Earth's external gravitational field is often modelled by a single finite set of external spherical harmonic coefficients. The coefficients are usually derived from satellite or terrestrial gravitational data or by a suitable combination of both. It is known, however, from previous theoretical studies that satellite and terrestrial coefficients are conceptually different and, in principle, do not match. On the one hand, both types can describe the external potential with an arbitrary accuracy in the space above the limit sphere encompassing the gravitating body. On the other hand, when it comes to realistic bodies, only terrestrial coefficients can achieve the same in the space that is below the limit sphere but external to the gravitating body. The price paid to achieve the latter is the fact that the terrestrial coefficients no longer match the satellite coefficients, introducing a conceptual coefficients inconsistency. Using a carefully designed simulated yet realistic closed-loop environment, we numerically reveal in this contribution the different nature of the two coefficients sets. Taking the irregularly-shaped asteroid (101955) Bennu as the gravitating body, we show that, unsurprisingly, the satellite coefficients indeed lead to an excellent accuracy outside the limit sphere (relative accuracy of 10^-14 in double precision) but produce grossly invalid results below the limit sphere due to the divergence of spherical harmonics. After this exercise, the real challenge of the study was to reliably compute terrestrial coefficients for as complex body as the asteroid Bennu. After computations that took altogether 90 CPU years, we were able to scrutinize the terrestrial coefficients with the relative accuracy of 10^-6 on the surface of Bennu, that is, below the limit sphere. The results clearly demonstrate the different nature of the two coefficients sets. For instance, it is evident that, from the theoretical point of view, it is rather dangerous to evaluate partial sums from terrestrial coefficients on the Earth's surface. Furthermore, some of the near-surface applications of terrestrial coefficients (e.g., quasigeoid-to-geoid separation or residual terrain modelling) become questionable. As a consolation, the accuracy and the resolution of our Earth's gravitational field models are currently so poor (or excellent, depending on the context) that it will probably take some time for us to encounter these effects with real-world Earth's gravitational data.