bluuebunny/crossref_metadata_2025 huggingface dataset:
Power generation forecast for a solar plant with a deep-learning method
Authors: Wu Yu-Ting , Lin Chang-Yu
Published: February 2023

In this study, we perform power generation forecast of a solar farm using deep learning. A long short-term memory (LSTM) network is applied to forecast time series data of the overall power production from a solar farm. An LSTM network can be considered as a recurrent neural network (RNN) looping with input data (e.g., measured power data) over time steps to update the network information. The network information also has records over all previous time steps. One can use an LSTM network to predict subsequent values of a time series (denoted as open loop forecasting) or sequence using previous time steps as input (denoted as closed loop forecasting). Both forecasting methods are built in the LSTM network. Preliminary results show that closed loop forecasting can allow to have predictions of solar power in more time steps, but less accurate than the other method.  
Coastal Currents and their Extremes in Singapore
Authors: Puah Jun Yu
Published: February 2023

COASTAL CURRENTS AND THEIR EXTREMES IN SINGAPOREJun Yu Puah*1, David Lallemant1,2, Ivan D. Haigh3, Kyle M. Morgan1,2, Dongju Peng2, Adam D. Switzer1,21Asian School of the Environment, Nanyang Technological University, Singapore2Earth Observatory of Singapore, Nanyang Technological University, Singapore 3School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK*a210012@e.ntu.edu.sg Extreme currents are integral as they affect ship navigation and public safety. However, research on extreme currents is scarce and further hampered by the lack of long-term observational records. In this study we estimate the characteristics of extreme shallow-water currents in Pulau Hantu and Kusu Island located in the Singapore Strait and investigate their potential drivers. We apply harmonic analysis to around 12 months of data to decompose the observed currents into tidal and residual components. The tail distribution of the residual component was estimated using extreme value analysis by fitting a non-homogeneous Poisson process to the data, accounting for temporal and directional dependences. Random simulations of tidal currents were then combined with residual currents via the Joint Probability Method to generate new observed current realizations. Finally, wind data was extracted from ERA5 Reanalysis to investigate how well monsoonal winds correlates with residual currents across monsoon periods. Tidal variance ranges from 29-69% across all sites, which is lower than expected given the dominance of tidal currents in the Singapore Strait. Extreme currents orient mainly in 2 directions along the coastline contours. Mean speed in Pulau Hantu is greater than Kusu Island and may be attributed to the hydrodynamic pressure gradient set up by the monsoons. Lastly, the stronger correlation observed in some sites during the inter-monsoon periods demonstrates the importance of localized winds from local systems such as Sumatra squalls in driving extreme currents. The variability of the study results highlights the challenges in modelling currents in the Singapore Strait given its complex bathymetry, equatorial weather patterns and complex tidal regime. Future work could include the integration of shipborne Automated Information Systems to examine extreme currents and evaluate the role of meteorological effects in driving extreme currents in the region. 
Resolving weather fronts increases the large-scale circulation response to Gulf Stream SST anomalies
Authors: Jnglin Wills Robert , Herrington Adam , Simpson Isla , Battisti David
Published: February 2023

Canonical understanding based on general circulation models (GCMs) is that the large-scale circulation responds only weakly to extratropical sea-surface temperature (SST) anomalies, compared to the larger influence of tropical SST anomalies. However, the horizontal resolution of modern GCMs, which ranges from roughly 200 km to 25 km, is too coarse to fully resolve mesoscale atmospheric processes such as weather fronts. Here, we investigate the large-scale atmospheric circulation response to idealized Gulf Stream SST anomalies in a variable resolution version of the Community Atmospheric Model (CAM6), with regional grid refinement of 14 km over the North Atlantic, and compare it to versions with 28-km regional grid refinement and global 111-km resolution. The high-resolution simulations show a large positive response of the wintertime North Atlantic Oscillation (NAO) to positive SST anomalies in the Gulf Stream, a 1-standard-deviation NAO anomaly for 2°C SST anomalies. The lower-resolution simulations show a much weaker response, and in some cases, a different spatial structure of the response. The enhanced large-scale circulation response at high resolution results from an increase in resolved vertical motions, which enables SST forcing to have a larger influence on transient-eddy heat and momentum fluxes. In response to positive SST anomalies, these processes contribute to a stronger North Atlantic jet that varies less in latitude, as is characteristic of the positive phase of the NAO. Our results suggest that the atmospheric circulation response to extratropical SST anomalies is fundamentally different at higher resolution. Regional refinement in key regions offers a potential pathway towards improving simulation of the atmospheric response to extratropical SST anomalies and thereby improving multi-year regional climate predictions.
New features of the ELSEM-Net electromagnetic monitoring stations network and analysis of recent data associated with strong earthquakes.
Authors: Politis Dimitrios Z. , Potirakis Stelios M. , Malkotsis Philopimin , Papadopoulos Nikolaos , Dimakos Dionysios , Exarchos Michael , Liadopoulos Efstratios , Contoyiannis Yiannis F. , Charitopoulos Angelos , Kontakos Kyriakos , Doukakis Dimitrios , Koulouras Grigorios , Melis Nikolaos , Eftaxias Konstantinos
Published: February 2023

The ELSEM-Net (hELlenic Seismo-ElectroMagnetics Network, http://elsem-net.uniwa.gr) is a telemetric network of ground-based monitoring stations for the study of fracture-induced electromagnetic emissions. It comprises 11 telemetric stations, spanning all over Greece, and has continuously been operated for almost 30 years. In this paper we present the new, custom designed, instrumentation of the telemetric stations. Specifically, we present both the hardware and the firmware/software used, from antennae to data acquisition and data management. Finally, we present recent recordings prior to significant strong earthquakes (EQs) that have happened in Greece, as well as the obtained analysis results, using nonlinear time series analysis methods, indicating that the acquired signals embed important features associated with the impending EQ.
The Prevalence and Impact of Heavy Tails on Hydrologic Extremes and Other Statistics
Authors: Vogel Richard , Lamontagne Jonathan , Dolan Flannery
Published: February 2023

The prevalence of heavy tailed (HT) populations in hydrology is becoming increasingly commonplace due in part to the increasing need and use of high frequency and high-resolution data.   In addition to the impact of HT on extremes, HT populations can have a profound impact on a wide range of other hydrologic statistics and methods associated with planning,  management and design for  extremes.   We review the known impacts of HT populations on the instability and bias in a wide range of commonly used hydrologic statistics. Experiments reveal that HT distributions result in the degradation of many commonly used statistical methods including the bootstrap, probability plots, the central limit theorem, and the law of large numbers.     We document the gross instability of perhaps the best-behaved statistic of all, the sample mean (SM) when computed from HT distributions.  The SM is ubiquitous because it is a component of and related to a myriad of statistical methods, thus its unstable behavior provides a window into future challenges faced by the hydrologic community.  We outline many challenges associated with HT data, for example, upper product moments are often infinite for HT populations, yet upper L-moment always exist, so that the theory of L-moments is uniquely suited to HT distributions and data.  We introduce a magnification factor for evaluating the impact of HT distributions on the behavior of extreme quantiles
Estimating hydraulic conductivity using extended leak-off test conducted during drilling large-diameter borehole
Authors: Jo Yeonguk , Song Yoonho , Park Sehyeok
Published: February 2023

Extended leak-off test (XLOT) is one of the in-situ tests, routinely conducted to evaluate integrity of the cased and cemented wellbores during deep borehole drilling, as well as in situ hydraulic properties at a casing shoe depth.We introduce results of the XLOT conducted in a large diameter borehole, which is drilled for installation of deep borehole based geophysical monitoring system to monitor micro-earthquakes and fault behavior of major linearments in the subsurface. The borehole was planned to secure a final diameter of 200 mm (or more) at a depth of ~1 km deep, with 12" diameter wellbore to intermediate depths, and 7-7/8" (~200 mm) to the bottom hole depths.We drilled first the 12" diameter borehole to approximately 504 m deep and installed API standard 8-5/8" casing, then cemented the annulus between the casing and bedrock. Then we carried out the XLOT, for several purposes such as confirming casing and cementing integrity, as well as estimating in-situ stress and hydraulic conductivity at the casing shoe depth. To that end, we drilled 4 m length interval to directly inject water and pressurize into the rock mass using the upper API casings. During the XLOT, we recorded flow rates and interval pressures in real time. Based on the logs, we tried to analyze hydraulic conductivity of the test interval, and compare the results with previously reported hydraulic properties measured in other ways.
Human-induced geohazards in Permian Basin, USA revealed by InSAR and numerical modeling
Authors: Lu Zhong , Zheng Weiyu , Karanam Vamshi , Kim Jinwoo
Published: February 2023

The Permian Basin, encompassing ~170,000 km2 of southeastern New Mexico and west Texas, consists of ancient marine rocks underlain by water-soluble rocks and multiple hydrocarbon-rich formations. Densely populated oil and gas producing facilities have impacted the stability of the solid-Earth, inducing long-lasting surface subsidence and uplift and the formation of sinkholes and fissures. The ground instability and the associated geohazards threaten the safe operation of key infrastructure such as roads, hydrocarbon facilities, pipelines, and water management facilities. Using multi-temporal and multi-band interferometric synthetic aperture radar (InSAR) datasets, we have mapped temporal behaviors of the geohazards on a weekly to monthly basis. The time-lapse InSAR measurements are compared to collected human activity data to reveal and correlate the causality of the geohazards with the type of anthropogenic perturbation (e.g., wastewater injection, CO2 flooding, abandoned well, salt dissolution, mining, etc.). We have quantified the impacts of human activities on the stability of the solid-Earth through numerical poroelastic modeling, which simulates the induced stress/pressure distribution in the strata and the resulting surface subsidence/uplift. By identifying the triggering factor(s) behind human-induced geohazards that have already occurred, our in-depth study provides insights for the mitigation of environmental impacts and assists the decision-making of public authorities and private oil and gas companies as they strive to minimize negative environmental impact and financial risk while supporting the sustainable growth of the Permian Basin’s petroleum industry.
PRIDE PPP-AR: an open-source scientific software with all-frequency PPP ambiguity resolution for geodesy, geophysics and photogrammetry applications
Authors: Geng Jianghui , Lin Jihang , Zeng Jing , Li Wenyi , Zhang Qiyuan
Published: February 2023

The modernized GNSS transmit more signals on various frequencies to suit different application scenarios. However, for a long time, ambiguity resolution has been available to PPP users only on a few signal frequencies specified by the PPP service provider, which prevents other signal frequencies from being used for high-precision positioning applications. Recently, the GNSS Research Center of Wuhan University offered a new version of open-source PRIDE PPP-AR software and a set of “all-frequency” PPP-AR products, that supports PPP users in achieving undifferenced ambiguity resolution on any dual-frequency ionosphere-free combination based on the same satellite phase clocks. The new feature of PRIDE PPP-AR was tested with GPS/Galileo/BDS observations from 200 multi-frequency IGS stations in the first 9 months of 2022. The mean wide-/narrow-lane ambiguity fixing rates can achieve 90% on most of the common dual-frequency combinations, including GPS L1/L2, the combination of Galileo E1 and Galileo E5a/E5/E5b/E6, and BDS-3 B1C/B2a and B1I/B2I. On the other common dual-frequency combinations except for the BDS-2 B1I/B2I, the mean wide-/narrow-lane ambiguity fixing rates can achieve 80%. On all the above dual-frequency combinations, the positioning RMS errors compared with the IGS weekly solutions are about 2 mm in the east and the north directions, and below 7 mm in the high direction. Additionally, the new version of PRIDE PPP-AR enables precise orbit determination for LEO satellites. The TurboEdit algorithm was improved with forward and backward moving window averaging (FBMWA) method to accommodate the need for achieving ambiguity resolution on fast motion objects. A comparison between the computed orbits and JPL’s precise orbits for GRACE-FO in 2019 shows that the 3D RMS difference is within 1.7 cm. The PRIDE PPP-AR was first released in 2019 and dedicated to expanding the scope of PPP-AR in geodetic researches. After several updates, this GNSS analysis tool now supports multi-day continuous processing, processing of very-high-rate GNSS data, and quasi-real-time processing with real-time archived PPP products. With the new features of all-frequency PPP-AR and PPP-AR on LEO satellites, the new version of PRIDE PPP-AR will be able to take full advantage of GNSS modernization to improve high-precision positioning accuracy in more research areas.
Main drivers of Indian Ocean dipole asymmetry revealed by a simple IOD model
Authors: Park Hyo-Jin , An Soon-Il , Kim Soong-Ki , Cai Wenju , Santoso Agus , Kim Daehyun , Kug Jong-Seong
Published: February 2023

Indian Ocean Dipole phenomenon (IOD) refers to a dominant zonal contrast pattern of sea surface temperature anomaly (SSTA) over tropical Indian Ocean (TIO) on interannual time scales. Its positive phase, characterized by anomalously warm western TIO and anomalously cold southeastern TIO, is usually stronger than its negative phase, namely a positively skewed IOD. Here, we investigate causes for the IOD asymmetry using a prototype IOD model, of which physical processes include both linear and nonlinear feedback processes, El Nino’s asymmetric impact, and a state-dependent noise. Parameters for the model were empirically obtained using various reanalysis SST data sets. The results reveal that the leading cause of IOD asymmetry without accounting seasonality is a local nonlinear process, and secondly the state-dependent noise, the direct effect by the positively skewed ENSO and its nonlinear teleconnection; the latter two have almost equal contribution. However, the contributions by each process are season dependent. For boreal summer, both local nonlinear feedback process and the state-dependent noise are major drivers of IOD asymmetry with negligible contribution from ENSO. The ENSO impacts become important in boreal fall, along with the other two processes. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2018R1A5A1024958)
The 1820s Marks a Shift to Hotter‐Drier Summers in Western Europe Since 13
Authors: Wang Lu , Liu Hongyan , Chen Deliang , Zhang Peng , Leavitt Steven , Liu Yu , Fang Congxi , Sun Changfeng , Cai Qiufang , Gui Zhengyang , Liang Boyi , Shi Liang , Liu Feng , Zheng Yukun , Grießinger Jussi
Published: February 2023

    Soil moisture is the primary indicator for assessing agricultural and ecological drought, and its relationship with temperature has a great impact on regional climates, such as triggering heat waves. So far, studies on the coupling relationship between soil moisture and temperature have mainly focused on arid or semi-arid regions with strong land-atmosphere coupling. However, less attention has been paid to humid regions with relatively weak coupling between soil moisture and temperature there. In recent years, a number of studies have found that heat waves in humid regions are directly related to the coupling of soil moisture and temperature. Nevertheless, historical changes of soil moisture and its relationship with temperature in humid areas are still unclear.    In this study, three sampling sites with published long-term tree ring δ18O records in England and France were selected to reconstruct the surface (0–10 cm) soil moisture changes in Western Europe (40°N–55°N, 10°W–10°E) from 1360 to 2000 AD. Various abrupt-change detecting tests (Mann-Kendall test, Yamamoto method, and Bernaola-Galvan segmentation algorithm) showed that soil moisture began to decline suddenly around 1820, with increasing dry years and decreasing wet years, and no wet years after 1950 . After 1820, the coupling of soil moisture and temperature was growing stronger than before. Compared with the historical period, the summer sea level pressure anomaly is stronger in the dry years after 1820, which may be related to the weakened westerly circulation and water vapor transport. These findings suggest that, in the context of global warming, hotter and drier conditions are occurring not only in arid regions, but also in humid western Europe. Under future warming scenarios, humid regions may also be threatened by hot droughts.
Circulation differences between two types of winter extreme cold air activity events in the middle-lower reaches of the Yangtze River and their relationship with the jet stream
Authors: Zhang Yaocun , Zhu Xuan
Published: February 2023

Based on the precipitation and minimum temperature data observed at the stations from 1981 to 2020, two types of winter cold air activity events in the middle-lower reaches of the Yangtze River are identified, which are strong cooling events with precipitation and only strong cooling events without precipitation (referred to as “cold-wet” and “cold-dry” events), respectively. The atmospheric circulation differences and the characteristics of cold and warm air activities in the two type events, and their connection with the jet stream are also examined. The results show that the frequency of cold air activity events in the middle-lower reaches of the Yangtze River decreases year by year, among which the frequency of cold-dry events decreases and the frequency of cold-wet events increases significantly. In addition, the cooling amplitude of cold-wet events is greater than that with no precipitation. When cold-wet events occur, the upper-level subtropical jet moves northward and the polar front jet is weaker. There is a tilting ridge in the middle level and the subtropical high is located westward. In the lower-level, the Siberian high is strengthened and the warm and humid air flowing from the southwest converges and ascends in the middle-lower reaches of the Yangtze River. However, when cold-dry events occur, the subtropical jet in the upper level is weaker and the polar front jet is stronger. The trough and ridge in the middle level are weaker and the subtropical high is located eastward. In the lower level, the Siberian high is located southward and the dry air flowing from the north diverges and sinks in the middle-lower reaches of the Yangtze River. In addition, compared with cold-wet events, the jet stream intensity index and the meridional wind position index fluctuate more frequently during cold-dry events, and the cold air activity duration is shorter.
Future ground-level summer ozone concentrations in Europe: the importance of ozone as predictor in a statistical downscaling approach
Authors: Kaspar-Ott Irena , Jahn Sally , Hertig Elke
Published: February 2023

Statistical downscaling models are used to estimate historical and future ozone concentrations in Europe for the summer months from April to September. The basis is formed by over 700 measuring stations from the hourly Air Quality eReporting ozone pollution data from the European Environment Agency. Daily maximum 8-hr running means (MDA8) as well as daily maximum 1-hr values (MDA1) of ozone are the target variables. Meteorological (ERA5) as well as ozone (CAMS) reanalysis data serve as predictors in the perfect prognosis (PP) approaches. A station-specific, individualized predictor screening guarantees site-specific optimums. The predictor selection is performed using regularization with varying shrinkage. Multiple Linear Regression (MLR) is used to model the relationship between all selected predictors and MDA8/ MDA1. An ensemble of seven CMIP6 Earth system models is used to estimate future ozone concentrations. Projections are calculated for the years 2041-2060 and 2081-2100 under two different future scenarios (SSP2-4.5 and SSP3-7.0). The CMIP6 data is bias corrected with a univariate quantile delta mapping method, before being used in the statistical models.With respect to predictor selection, a sensitivity study is conducted, testing different sets of predictors to examine their influence on future ozone concentrations. Predictor sets with and without ozone, with only thermal and radiative predictors, and additionally thermo-dynamical or circulation-dynamical information are analyzed, in addition to the site-specific optimums described above.The projection results of the different predictor settings highlight the importance of ozone as predictor. In all predictor sets with included ozone, the results of the two scenarios SSP2-4.5 and SSP3-7.0 differ in their sign depending on the scenario used. The SSP2 scenario, called "Middle of the Road", leads to decreasing ozone concentrations in Europe, while the more pessimistic SSP3 scenario results in partly strong increases of harmful ground-level ozone concentrations. In contrast, all predictor sets that do not take ozone into account show consistently positive change signals.On the one hand, our results point to the need to include information on emission changes in statistical assessments in order to obtain a realistic picture of future ozone development. Furthermore, our research underscores the need to further reduce air pollution in Europe to better protect human health from direct emissions such as NOx and indirect pollutants such as ozone.
Quantifying the Predictability of ENSO Complexity Using a Statistically Accurate Multiscale Stochastic Model and Information Theory
Authors: Fang Xianghui , Chen Nan
Published: February 2023

An information theory based framework is developed to assess the predictability of the ENSO complexity, which includes different types of the ENSO events with diverse characteristics in spatial patterns, peak intensities and temporal evolutions. The information theory advances a unique way to quantify the forecast uncertainty and allows to distinguish the predictability limit of each type of event. With the assistance of a recently developed multiscale stochastic conceptual model that succeeds in capturing both the large-scale dynamics and many crucial statistical properties of the observed ENSO complexity, it is shown that different ENSO events possess very distinct predictability limits. Beyond the ensemble mean value, the spread of the ensemble members also has remarkable contributions to the predictability. Specifically, while the result indicates that predicting the onset of the eastern Pacific (EP) El Ninos is challenging, it reveals a universal tendency to convert strong predictability to skillful forecast for predicting many central Pacific (CP) El Ninos about two years in advance. In addition, strong predictability is found for the La Nina events, corresponding to the effectiveness of the El Nino to La Nina transitions. In the climate change scenario with the strengthening of the background Walker circulation, the predictability of sea surface temperature in the CP region has a significant response with a notable increase in summer and fall. Finally, the Gaussian approximation exhibits to be accurate in computing the information gain, which facilitates the use of more sophisticated models to study the ENSO predictability.
In-kitchen aerosol exposure in Korogocho informal settlement in Nairobi
Authors: Sitati Cynthia
Published: February 2023

In urban set-ups, the use of charcoal as a source of energy is predominant among the urban poor (low-income earners). In the urban informal settlements such as the Korogocho slums in Nairobi, households rely on kerosene and charcoal for cooking. In some cases, it has been reported that some poorest households in these informal settlements use plastic waste, cloth rags, and other unconventional fuels due to unaffordability to access conventional sources of energy. As a result, the fuels generate high levels of harmful indoor air pollutants. This study was part of the wider project in which we assessed exposure to in-kitchen particulate matter (PM2.5 and PM10) in 60 low-income homes across 12 cities, including Nairobi (Kenya). We aim to ensure cleaner air in homes and promote the development of equitable, inclusive, social, and environmental benefits in one of Nairobi’s informal settlements as indoor environments have become more important during the Covid-19 pandemic thereby necessitating the need to ensure less exposure of households to harmful pollutants. We assess indoor air pollution exposure by monitoring aerosol and carbon dioxide data in five different households in the informal settlement of Korogocho in Nairobi. We engaged stakeholders through co-designed webinars, outreach, and capacity-building activities. The study aimed at developing exposure strategies and assessing the feasibility of similar studies in other parts of the country. The results showed that fuel, kitchen volume, cooking type, and ventilation were the most prominent factors affecting in-kitchen exposure. There is an urgent need for increased awareness of improved cooking practices and minimizing passive occupancy in kitchens to mitigate harmful cooking emissions.
 
Societal interest and willingness to pay for green roofs in Sardinia
Authors: Cristiano Elena , Deidda Roberto , Viola Francesco
Published: February 2023

Among the different nature-based solutions proposed for the sustainable development of urban areas, green roofs are becoming more and more popular, thanks to their multiple benefits. Indeed, these nature-based solutions reduce the pluvial flood risk during rainfall events, contribute to the thermal insulation of buildings, mitigate the urban heat island effect, and improve the air quality. The knowledge that citizens have about green roofs, the interest and willingness to pay for their installation are still poorly investigated and quantified, although this meta-information could be a valid support and guidance for policy makers and urban planners. In this work, we investigated, through an anonymous online survey, the perception of people living in Sardinia on the most common urban environmental issues (i.e., urban flood, increase of temperature, energy consumption, air pollution and lack of green spaces), and the willingness to pay for green roof installation on both public and private roofs. We estimated the empirical relation among environmental issues awareness and the willingness to pay for a specific green solution while trying to relate the latter to socio demographic characteristics. Results show that citizens are very interested in having green roofs on public building, and on average they are willing to pay around 35 euro per year for their installation and maintenance. The interest for green roofs on private building is, on the other hand, lower than on public ones, due to the high installation and maintenance costs. Moreover, when possible, citizens would rather have solar panels instead of green roofs, since they fully perceive the economic advantages deriving from the installation and are not fully aware of the green roof benefits.
Evaluation of optical accelerometry for next generation gravimetry missions
Authors: Kupriyanov Alexey , Reis Arthur , Schilling Manuel , Müller Vitali , Müller Jürgen
Published: February 2023

Twenty years of gravity observations from the satellite missions GRACE, GOCE, GRACE-FO have provided unique data about mass redistribution processes in the Earth system, such as melting of Greenland’s ice shields, sea level changes, underground water depletion, droughts, floods, etc. Ongoing climate change underlines the urgent need to continue this kind of observations utilizing Next Generation Gravimetry Missions (NGGM) with enhanced instruments. Here, we focus on accelerometers (ACC).Drifts of the electrostatic accelerometers (EA) are one of the limiting factors in the current space gravimetry missions dominating the error contribution at low frequencies (<10−3 Hz). The focus of this study is on the modelling of enhanced EAs with laser-interferometric readout, so called ‘optical accelerometers’ and evaluating their performance at Low Earth Orbits (LEO). Contrary to GRACE(-FO) or GOCE capacitive accelerometers, optical ones sense the motion of the test mass (TM) in one or more axes by applying laser interferometry. Combination of sensing in multiple directions and of several test masses would lead to enhanced gradiometry which would improve the determination of the static gravity field to a higher spatial resolution and may even enable to observe time-variable gravity changes.Our research is based on very promising results of the mission LISA-Pathfinder which has demonstrated the benefit of using a drag-free system in combination with optical accelerometry and UV TM discharge which allowed sensing of non-gravitational accelerations several orders of magnitude more accurate than it is realized in current gravity missions like GRACE-FO. This research project is carried out in close collaboration with the IGP and the DLR-SI, to provide - on the long run - a roadmap for improved angular and linear accelerometry for NGGM.In this presentation, we now introduce a framework for modeling enhanced EA with laser-interferometric readout mainly developed by IGP including major noise sources, like actuation noise, capacitive sensing, stiffness and thermal bias. Also, parametrization of the developed ACC model will be discussed including different TM weights and TM-electrode housing gaps. Finally, improved results of the recovered gravity field will be shown based on various mission scenarios applying optical accelerometry and gradiometry.This project is funded by: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 434617780 – SFB 1464.
Alkalinity and Sensitivity to Alkalinity Enhancement in CMIP6 Earth System Models
Authors: Hinrichs Claudia , Hauck Judith , Völker Christoph , Köhler Peter
Published: February 2023

We evaluated the large-scale alkalinity distribution in 14 CMIP6 models against the observational data set GLODAPv2 and found that most models as well as the multi-model-mean underestimate alkalinity at the surface and in the upper ocean, while overestimating alkalinity in the deeper ocean. The dissection of the global mean alkalinity biases into their contribution from physical processes (preformed alkalinity), remineralization, and carbonate formation and dissolution showed that the bias stemming from the physical redistribution of alkalinity is dominant. However, below the upper few hundred meters the bias from carbonate dissolution can become similarly important as physical biases, while the contribution from remineralization processes is negligible. In light of ongoing and planned projects involving ocean alkalinity enhancements experiments using ESMs, a back-of-the-envelope calculation was conducted with each model’s global mean surface alkalinity and dissolved inorganic carbon (DIC) as input parameters. It was shown that the degree of compensation of DIC and alkalinity biases at the surface matters more than the alkalinity biases themselves for additional CO2 uptake capacity. The global mean surface alkalinity bias relative to GLODAP ranges from -3.6% to +2.1% with a mean of -1.1%, while for DIC the relative bias ranges from -2.6% to +2.5% with a mean value of -0.6%. Because of this partial compensation, all but two of the here evaluated CMIP6 models overestimate the Revelle factor at the surface and thus overestimate the CO2-draw-down after an alkalinity addition of 100 µmol kg-1  by up to 13% and the pH increase by up to 7.2%. This probable overestimate has to be taken into account when reporting on efficiencies of ocean alkalinity enhancement experiments using CMIP6 ESMs.
Decreased inter-annual streamflow variability are found in snow-affected catchments by using the second-order Budyko framework
Authors: Liu Ziwei , Wang Taihua , Han Juntai , Yang Wencong , Yang Hanbo
Published: February 2023

With persistent global warming, more precipitation will land on the earth's surface as rainfall instead of snowfall. Here, based on observations from hundreds of catchments, we proposed a framework (the second-order Budyko framework) to investigate hydro-climatic relationships between annual streamflow and snowfall fraction. Results show that in addition to the mean annual streamflow, the inter-annual streamflow variability will also decrease with lower snowfall fraction in the context of warming. The positive relationship between streamflow variability and snowfall fraction may result from the asymmetric hydrological effects of snowfall in the wet and dry years. To our knowledge, it is the first attempt to detect the role of snowfall on the streamflow variability. This study provides new way and understandings of the second-order hydro-climatic effects, and these findings will facilitate decisions for water resource management in a changing climate.
Influence of urbanization on flood extent changes at the global level
Authors: Mazzoleni Maurizio , Dottori Francesco , Cloke Hannah L. , Di Baldassarre Giuliano
Published: February 2023

Anthropogenic actions are progressively affecting most river basins worldwide, resulting in changes in hydrological processes and thus influencing water availability. Despite previous studies aimed at quantifying the relationship between urbanization and extreme flooding events at local to regional scales, it is still unclear how human presence has influenced the occurrence of seasonal surface water. As a result, global patterns remain largely unknown.In this study, we perform a global analysis of large river basins and uncover global trends of annual maximum flood extent and impervious area, as well as their relationships with rainfall and snowmelt, over the past three decades. Hydrological and urban dynamics are computed by using multiple earth observation datasets.We find that hydroclimatic variability alone cannot explain changes in annual maximum flood extent for 75% of the analyzed river basins worldwide. We also observe increasing trends in both annual maximum flood extent and the urbanized area within floodplains, especially in Asian and African river basins. Our findings reveal an emerging global reciprocal relationship between urbanization processes and maximum flood extent changes. Both rainfall and urbanized area can explain changes in the annual maximum flood extent in 57% of the analyzed basins.Our findings highlight the need for a better understanding of the influence of human presence on changes in seasonal water dynamics at the global scale. In view of the worldwide rapid development of urban areas, these findings can inform the process of flood risk management and help improve targeted policy and land use interventions
Estimating and mapping forest canopy fuel parameters from GEDI LiDAR data in Europe
Authors: Aragoneses Elena , García Mariano , Chuvieco Emilio
Published: February 2023

Spatially-explicit information on canopy fuel parameters is key for wildfire propagation modelling, emission estimations and risk assessment. This work aims to develop easily-replicable methods to estimate critical fuel canopy parameters from spaceborne LiDAR observations acquired by the Global Ecosystem Dynamics Investigation (GEDI) sensor onboard the International Space Station. GEDI-like pseudowaveforms were modelled from discrete Airborne Laser Scanning (ALS) data and used to select the best GEDI predictor metrics to derive European wall-to-wall forest height and canopy cover maps. Then, GEDI spaceborne footprints were used to generate continental maps of canopy parameters through a two-steps approach: 1) Spatial interpolation of GEDI footprints inside homogeneous forest fuel type polygons, and 2) Modelling machine learning algorithms for the forest fuel type polygons without GEDI footprints inside, using auxiliary multispectral and RADAR imagery and biophysical variables. Our results show the capabilities of remote sensing and GEDI to estimate and map the spatial patterns of critical forest canopy fuel parameters in fire risk prevention and contribute to generating the necessary tools to develop an integrated risk-wise strategy that reduces fire vulnerability of ecosystems across Europe.
High-resolution (1 km) Köppen-Geiger maps for 1901–2099 based on constrained CMIP6 projections for seven socio-economic scenarios
Authors: Beck Hylke , McVicar Tim , Vergopolan Noemi , Berg Alexis , Lutsko Nicholas , Dufour Ambroise , Zeng Zhenzhong , Jiang Xin , van Dijk Albert , Miralles Diego
Published: February 2023

We present Version 2 of our widely used 1-km Köppen-Geiger climate classification maps for historical and future climate conditions. The historical maps (1901–1930, 1931–1960, 1961–1990, 1991–2020) are based on high-resolution, observation-based climatologies, while the future maps (2041–2070 and 2071–2099) are based on downscaled and bias-corrected climate projections for seven shared socio-economic pathways (SSPs). We evaluated 64 climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6) and kept a subset of 40 with the most plausible CO2-induced warming rates. Under the “middle of the road” scenario SSP2-4.5, the global land surface area (excluding Antarctica) with suitable climatic conditions for tropical, arid, temperate, cold, and polar vegetation is projected to show a net change of +9 %, +3 %, −3 %, −2 %, −33 %, respectively, in 2071–2099 (with respect to 1991–2020). The Köppen-Geiger maps, including associated confidence estimates, the underlying monthly air temperature and precipitation data, and sensitivity metrics for CMIP6 climate models are available at www.gloh2o.org/koppen.
Effect of damming on riverine strontium geochemical behavior: Evidence from 87Sr/86Sr analysis
Authors: Qiu Xiaolong , Wang Baoli
Published: February 2023

    River damming alters biogeochemical cycles in river continuum. Yet, its effect on the biogeochemical behavior of riverine strontium (Sr) is still unclear. Here, we measured riverine 87Sr/86Sr in both dissolved and particulate phases and relevant parameters in karst cascade reservoirs of Southwest China, and simulated 87Sr/86Sr fractionation during biological processes through experimental incubation of model phytoplankton. The results showed that the dissolved 87Sr/86Sr was rather homogeneous across the water body and nearly identical to inorganic particulate-bound 87Sr/86Sr, and reservoir Sr mainly sourced from carbonate weathering. However, the dissolved Sr concentrations were stratified and increased with depths of the reservoir water columns. This stratification was likely caused by phytoplankton and the precipitation and dissolution of calcite, with the stratified strength controlled by reservoir hydraulic loads. A long-term loads along cascade reservoirs thus could result in a significant increase in dissolved Sr concentrations rather than 87Sr/86Sr. The culture experiment indicated that the dissolved Sr was massively captured by the phytoplankton during which insignificant 87Sr/86Sr fractionation occurred. Thus, the 87Sr/86Sr of reservoir phytoplankton would conserve the dissolved 87Sr/86Sr. The distinctly lower 87Sr/86Sr of phytoplankton than terrestrial organic particulates highlights its potential to distinguish autochthonous and allochthonous sources of reservoir particulate matter. This study demonstrated that damming largely alters the elemental and isotopic distribution of riverine Sr and would deepen the understanding of Sr biogeochemistry in dammed rivers.
The balance between turbulent and convection-driven plasma vorticity in the Earth’s ionosphere
Authors: Chisham Gareth , Freeman Mervyn
Published: February 2023

Measurements of ionospheric flow vorticity can be used for studying ionospheric plasma transport processes, such as convection and turbulence, over a wide range of spatial scales. Here, we present the spatial variation across the northern hemisphere high-latitude ionosphere of probability density functions (PDFs) of ionospheric vorticity as measured by the Super Dual Auroral Radar Network (SuperDARN) over a six-year interval (2000-2005 inclusive). These PDFs are subdivided for different polarities of the By component of the Interplanetary Magnetic Field (IMF), which allows the separation of the observed PDFs into two distinct components. These components relate to: (1) The large-scale ionospheric convection flow driven by magnetic reconnection, and (2) Meso- and small-scale processes such as turbulence. The convection vorticity PDFs are single-sided and well fit by Weibull distributions, whereas the turbulence vorticity PDFs are double-sided and symmetric, and are well fit by q-exponential distributions. Both the observed model distributions can be understood in the framework of solutions of the stationary Fokker-Planck equation for different environmental plasma conditions.
Application of the LAND-SUITE software with a benchmark dataset for landslide susceptibility zonation
Authors: Bornaetxea Txomin , Yazdani Mina , Rossi Mauro
Published: February 2023

We propose the usage of LAND-SUITE software to carry out 16 landslide susceptibility models exploiting the benchmark dataset provided by the session organizers. The software allows the application of Linear Discriminat Analysis (LDA), Logistic Regression (LR) and Quadratic Discriminant Analysis (QDA) as statistical methods, together with the Combination Forecast Model (CFM), which combines the outputs of the former three methods. Each of the mentioned models has been applied considering the two provided different landslide presence variables (presence1 and presence2), resulting in 8 susceptibility maps that takes into account the complete set of explanatory variables. Then, we have taken advantage of the variables analysis outputs provided by LAND-SUITE, and the process has been repeated with a reduced set of 10 explanatory variable. The variables selection has been carried out following the principles of independence between the explanatory variables, and trying to optimize the contribution of each of them to the model performance, for which leave-one-out tests and significance p-value of the LR outputs have been consulted. Results show a slight, but generalized, improvement of the model performances when the presence2 dataset is used, against the presence1. The model performance is also maintained or very sensitively decreased when the amount of explanatory variables is reduced from 26 to 10. However, the Area Under the ROC Curve (AUC) ranges between 0.75 and 0.82 in any of the tests. In addition, 9 out of the 10 selected variables are the same for both presence1 and presence2 tests. Uncertainty associated to each of the models has been also computed by means of the bootstrap resampling method.
Towards understanding the effect of parametric aerosol uncertainty on climate using a chemical transport model perturbed parameter ensemble.
Authors: Bouchahmoud Meryem , Bergman Tommi , Williamson Christina
Published: February 2023

Aerosols in the climate system have a direct link to the Earth’s energy balance. Aerosols interact directly with the solar radiation through scattering and absorption; and indirectly by changing cloud properties. The effect aerosols have on climate is one of the major causes of radiative forcing (RF) uncertainty in global climate model simulations. Thus, reducing aerosol RF uncertainty is key to improving climate prediction. The objective of this work is to understand the magnitude and causes of aerosol uncertainty in the chemical transport model TM5.Perturbed Parameter Ensembles (PPEs) are a set of model runs created by perturbing an ensemble of parameters. Parameters are model inputs, for this study we focus on parameters describing aerosol emissions, properties and processes, such as dry deposition, aging rate, emissions to aerosols microphysics. PPEs vary theses parameters over their uncertainty range all at once to study their combine effect on TM5.Varying these parameters along with others through their value range, will reflect on TM5 outputs. The TM5 outputs parameters we are using in our sensitivity study are the cloud droplet number concentration and the ambient aerosol absorption optical thickness at 550nm.Here we discuss the design of the PPE, and one-at-a-time sensitivity studies used in this process. The PPE samples the parameter space to enable us to use emulation. Emulating is a machine learning technique that uses a statistical surrogate model to replace the chemical transport model. The aim is to provide output data with more dense sampling throughout the parameter space. We will be using a Gaussian process emulator, which has been shown to be an efficient technique for quantifying parameter sensitivity in complex global atmospheric models.We also describe plans to extend this work to emulate an aerosol PPE for EC-Earth. The PPE for EC-Earth will also contain cloud parameters that will vary over their uncertainty range together with the aerosol parameters to examine the influence of aerosol parametric uncertainty on RF. 