bluuebunny/crossref_metadata_2025 huggingface dataset:
RAGAM MEDIA PEMBELAJARAN SPEAKING DI MASA COVID -19
Authors: JUPRI JUPRI
Published: June 2022

English subjects are one of the subjects that have been greatly affected by the Covid-19 outbreak, especially for learning speaking skills because the learning demands must be carried out face-to-face. The main purpose of speaking skills is to create communication with various forms of creative expression. The purpose of this communication cannot be carried out normally because face-to-face learning is not permitted, in which face-to-face learning is a characteristic of speaking learning. This study aims to describe the choice of various learning media used by teachers (lecturers) in carrying out speaking lessons during the Covid-19 period. This research is a qualitative research using library research method which aims to find, read and examine research reports related to speaking learning media during the covid period and library materials that contain relevant theories related to the research conducted. The hope from this literature research is that teachers will be able to determine an elective solution to the speaking learning media that will be used in their learning by not ignoring the advantages and disadvantages as well as the situation and condition of the learner when learning takes place during this pandemic.
ABSTRAKMata pelajaran bahasa Inggris menjadi salah satu mata pelajaran yang sangat terdampak oleh wabah Covid-19 terutama untuk pembelajaran keterampilan berbicara karena tuntutan pembelajarannya  harus dilaksanakan secara tatap muka. Tujuan utama dari keterampilan berbicara (Speaking) adalah untuk menciptakan komunikasi dengan beragam bentuk ekspresi yang kreatif. Tujuan komunikasi tersebut tidak bisa terlaksana secara normal karena tidak diijinkannya pembelajaran tatap muka, yang mana pembelajaran tatap muka merupakan ciri khas pembelajaran berbicara (speaking). Penelitian ini bertujuan untuk mendiskripsikan pilihan ragam media pembelajaran yang digunakan oleh para guru ( dosen ) dalam melaksanakan pembelajaran speaking di masa Covid-19. Penelitian ini adalah penelitian kwalitatif menggunakan metode penelitian pustaka ( library research) yang bertujuan untuk mencari, membaca dan menelaah laporan-laporan hasil penelitian terkait media pembelajaran speaking di masa covid dan bahan pustaka yang memuat teori-teori yang relevan terkait dengan penelitian yang  dilakukan. Harapan dari penelitian pustaka ini adalah agar para pengajar nantinya bisa menentukan solusi pilihan ( elective solution) terhadap media  pembelajaran speaking yang akan digunakan dalam pembelajarannya dengan tidak mengabaikan kelebihan dan kekurangannya serta situasi dan kondisi pembelajar saat pembelajaran berlangsung  di masa pandemi ini
MOTIVASI BELAJAR MAHASISWA POLITEKNIK NEGERI SRIWIJAYA PADA PROSES BELAJAR BAHASA INGGRIS SELAMA PEMBELAJARAN JARAK JAUH : SUATU STUDY NARATIF
Authors: UJIHANTI MURWANI , ARDIANSYAH WELLY , ARYANTI NURUL , FARAGUSTA AHMAD LEO , RISNAWATI RISNAWATI
Published: June 2022

The energy that drives the spirit of learning is the motivation to learn. This motivation is fluctuating, sometimes strong and sometimes weak. Under normal circumstances, before the pandemic period, students came to class on time to take lessons. They can ask the teacher directly. Also, lecturers can see student responses directly, either implicitly or explicitly. Implicit responses can be seen from student gestures during the learning process in class. The problem that occurs is the arrival of a pandemic that causes all elements in the education system to suddenly have to adjust to new things. This change has an impact on changes in student learning motivation. The problem faced is the change in learning to the online system causes changes in students' learning motivation. These changes were studied using the descriptive inquiry method. The method of data collection was done by observing and describing "thinking aloud" student experiences in writing during distance learning. Some students managed to adapt to the pandemic situation and conditions and some students reacted less positively. The cause of the decline in learning motivation experienced by the study population was a sudden change due to the impact of the Covid-19 pandemic.
ABSTRAKEnergi pendorong semangat belajar adalah motivasi belajar. Motivasi ini sifatnya fluktuatip, adakalanya kuat dan kadang melemah. Pada keadaan normal, sebelum masa pandemi, para mahasiswa datang ke kelas tepat waktu untuk mengikuti pelajaran. Mereka dapat bertanya kepada dosennya secara langsung. Juga dosen dapat melihat respond mahasiswa secara langsung, baik respon secara implisit maupun explisit. Respon implisit dapat dilihat dari gesture mahasiswa selama mengikuti proses belajar di kelas. Permasalahan yang terjadi adalah datangnya pandemi yang menyebabkan semua unsur dalam sistim pendidikan secara tiba-tiba harus menyesuaikan diri dengan hal baru. Perubahan ini berdampak pada perubahan motivasi belajar mahasiswa. Permasalahan yang dihadapi adalah perubahan belajar ke sistim daring menyebabkan perubahan motivasi belajar peserta didik. Perubahan ini dipelajari dengan menggunakan Metode descriptive inquiry. Cara pengumpulan data dilakukan dengan cara observasi dan deskripsi “thinking aloud” pengalaman mahasiswa dalam bentuk tulisan selama belajar jarak jauh. Sebagian peserta didik berhasil menyesuaikan diri dengan situasi dan kondisi pandemi dan sebagian peserta didik bereaksi kurang positip. Penyebab menurunnya motivasi belajar yang dialami oleh populasi kajian ini adalah perubahan mendadak karena dampak masa pandemic Covid-19.
MENINGKATKAN HASIL BELAJAR IPA KELAS VIII. D SMP NEGERI 1 TEMON MELALUI PEMBELAJARAN PETA KONSEP
Authors: SUGIYARTI SITI
Published: June 2022

This study is an attempt to determine the improvement of science learning outcomes in class VIII D SMP Negeri 1 Temon through concept map learning. This research is Classroom Action Research (CAR), which consists of three cycles and each cycle includes planning, implementation, observation, and reflection. The instrument used is a test instrument in the form of a learning outcome test and a non-test instrument in the form of an observation sheet. The results of the study show that concept map learning is very effective on student learning outcomes that are applied in science learning, this is evidenced by an increase in student science learning outcomes from cycle I to cycle III. In the first cycle, only 16 students (47.06%) completed, while 18 students (52.94%), the average student learning outcomes in the first cycle were 61.91. In the second cycle, students who completed increased by 32 people (94.12%), while those who did not finished decreased to 2 people (5.88%), the average value of student learning outcomes increased in the second cycle by 72.41. In the third cycle, 34 students completed (100%), and there were no students who did not complete (0%), and the average value of student learning outcomes increased in the third cycle of 81.00.
ABSTRAKPenelitian ini merupakan usaha untuk mengetahui peningkatan hasil belajar IPA pada siswa kelas VIII D SMP Negeri 1 Temon melalui pembelajaran peta konsep. Penelitian ini adalah Penelitian Tindakan Kelas (PTK), yang terdiri dari tiga siklus dan setiap siklus meliputi perencanaan, pelaksanaan, pengamatan, dan refleksi. Instrumen yang digunakan adalah instrumen tes yang berupa tes hasil belajar dan instrumen non tes berupa lembar observasi. Dari hasil penelitian memperlihatkan bahwa melalui pembelajaran peta konsep sangat efektif terhadap hasil belajar siswa yang diterapkan dalam pembelajaran IPA, hal ini dibuktikan dengan adanya peningkatan hasil belajar IPA siswa dari siklus I hingga siklus III. Pada siklus I siswa yang tuntas hanya 16 orang (47,06%), sedangkan yang belum tuntas sebanyak 18 orang (52,94%), nilai rata-rata hasil belajar siswa siklus I adalah 61,91. Pada siklus II siswa yang tuntas meningkat sebesar 32 orang (94,12%), sedangkan yang belum tuntas menurun menjadi 2 orang (5,88%), nilai rata-rata hasil belajar siswa meningkat pasa siklus II sebesar 72,41. Pada siklus III siswa yang tuntas sebesar 34 orang mencapai (100%), dan tidak ada murid yang tidak tuntas (0%), dan nilai rata-rata hasil belajar siswa semakin meningkat pada siklus III sebesar 81,00.
Seasonal updraft speeds change cloud droplet number concentrations in low-level clouds over the western North Atlantic
Authors: Kirschler Simon , Voigt Christiane , Anderson Bruce , Campos Braga Ramon , Chen Gao , Corral Andrea F. , Crosbie Ewan , Dadashazar Hossein , Ferrare Richard A. , Hahn Valerian , Hendricks Johannes , Kaufmann Stefan , Moore Richard , Pöhlker Mira L. , Robinson Claire , Scarino Amy J. , Schollmayer Dominik , Shook Michael A. , Thornhill K. Lee , Winstead Edward , Ziemba Luke D. , Sorooshian Armin
Published: June 2022

Abstract. To determine the impact of dynamic and aerosol processes on marine low clouds, we examine the seasonal impact of updraft speed w and cloud
condensation nuclei concentration at 0.43 % supersaturation (NCCN0.43%) on the cloud droplet number
concentration (NC) of low-level clouds over the western North Atlantic Ocean. Aerosol and cloud properties were measured with
instruments on board the NASA LaRC Falcon HU-25 during the ACTIVATE (Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment)
mission in summer (August) and winter (February–March) 2020. The data are grouped into different NCCN0.43% loadings, and the
density functions of NC and w near the cloud bases are compared. For low updrafts (w < 1.3 m s−1), NC in
winter is mainly limited by the updraft speed and in summer additionally by aerosols. At larger updrafts (w > 3 m s−1),
NC is impacted by the aerosol population, while at clean marine conditions cloud nucleation is aerosol-limited, and for high
NCCN0.43% it is influenced by aerosols and updraft. The aerosol size distribution in winter shows a bimodal distribution in
clean marine environments, which transforms to a unimodal distribution in high NCCN0.43% due to chemical and physical aerosol
processes, whereas unimodal distributions prevail in summer, with a significant difference in their aerosol concentration and composition. The
increase of NCCN0.43% is accompanied with an increase of organic aerosol and sulfate compounds in both seasons. We demonstrate
that NC can be explained by cloud condensation nuclei activation through upwards processed air masses with varying fractions of
activated aerosols. The activation highly depends on w and thus supersaturation between the different seasons, while the aerosol size distribution
additionally affects NC within a season. Our results quantify the seasonal influence of w and NCCN0.43%
on NC and can be used to improve the representation of low marine clouds in models.
Accuracy of numerical wave model results: Application to the Atlantic coasts of Europe
Authors: Alday Matias , Ardhuin Fabrice , Dodet Guillaume , Accensi Mickael
Published: June 2022

Abstract. Numerical wave models are generally less accurate in the coastal ocean than offshore. It is generally suspected that a number of factors specific to coastal environments can be blamed for these larger model errors: complex shoreline and topography, relatively short fetches, combination of remote swells and local wind seas, less accurate wind fields, presence of strong currents, bottom friction, etc. These factors generally have strong local variations, making it all the more difficult to adapt a particular model setup from one area to another. Here we investigate a wide range of modelling choices including forcing fields, spectral resolution and parameterizations of physical processes in a regional model that covers most of the Atlantic and North Sea coasts. We show that the accurate propagation of waves from offshore is probably the most important factor on exposed shorelines, while other specific effects can be important locally, including winds, currents and bottom friction.
Dynamics of blocked weather regimes in the Atlantic-European region: a combined PV and local wave activity approach
Authors: Teubler Franziska , Polster Christopher , Wirth Volkmar , Hauser Seraphine , Grams Christian , Riemer Michael
Published: June 2022

Atmospheric blocking events are high-pressure weather events which block the mid-latitude westerly flow and can last from days to weeks. Owing to their persistence they can lead to extreme surface weather in the affected regions. Until now the largest forecast busts are associated with the onset of atmospheric blocking due to their complex dynamical nature. 

In this work we investigate atmospheric blocking dynamics through the lens of four year-round blocked weather regimes in the Atlantic-European region. It is of our interest to compare the mid-latitude dynamics of these weather regimes, namely Atlantic Ridge, Greenland Blocking, Scandinavian Blocking and European Blocking by a PV framework and a local wave activity framework. The PV framework is applied on isentropes intersecting the tropopause. The PV dynamics quantify downstream dispersion of wave energy, PV eddy fluxes, baroclinic growth, and divergent outflow. The latter is assumed to communicate the impact of mid-tropospheric latent heat release to tropopause height. We complement the diagnostic by the finite-amplitude local wave activity budget.

We discuss the different dynamics for the four weather regimes by time-lagged composites from the last 40 years in the ERA5-reanalysis and -reforecast datasets. Our analysis reveals among others an intriguing variability in formation: Scandinavian blocking appears as part of an Rossby wave packet (RWP) propagating into northern Asia, whereas European blocking terminates the RWP.  We further find that moist-baroclinic growth has an important but mostly ‘’indirect’ effect on the formation of the blocked regimes: ”indirect” in the sense that the associated ridge amplification occurs upstream of the region over that the regime is subsequently established.
DWD Pilotstation – Evaluating ground-based remote sensing systems for future observing networks
Authors: Knist Christine , Kayser Markus , Löffler Moritz , Vural Jasmin , Schomburg Annika , Görsdorf Ulrich , Lauermann Felix , Leinweber Ronny , Klink Stefan , Lehmann Volker
Published: June 2022

The latest generation of active and passive ground-based remote sensing instruments, often called “profilers”, has shown its potential for continuous and high-resolution measurements of thermodynamic and kinematic vertical profiles as well as particle-related profiles. It is precisely these observations of the atmospheric boundary layer that are increasingly needed to improve the forecast quality of high-resolution numerical weather prediction (NWP) and nowcasting.

For this purpose, the DWD has initiated the project “Pilotstation” to evaluate options for a qualitative network expansion with suitable surface remote sensing profilers. Currently, we assess the following profilers in a dedicated testbed at Lindenberg Observatory: Doppler lidar, microwave radiometer, water vapor broadband-DIAL, and cloud radar. Furthermore, we plan to evaluate a compact Raman lidar in the future. At DWD, the assessment of candidate systems takes place holistically focusing on all aspects of instrument reliability, operational sustainability, data quality, and on the potential benefit for the NWP using assimilation experiments. This implies efforts to standardize data processing steps and data formats, the development of software tools to support network operations and the proper integration of the observations in the data assimilation system. After the initial testing and evaluation at the Lindenberg Observatory, a suite of instruments will be installed at the weather station in Aachen-Orsbach to enable an end-to-end testing in an operational framework.

We give an overview of the ongoing project and present results regarding the various aspects: operations and sustainability, data quality and assimilation tests for the different testbed instruments and observations. This contribution complements the efforts of network development for future operational use within the frame of the EUMETNET's E-PROFILE observations program and the COST action PROBE.
Urban induced modification of precipitation - Findings from a systematic literature review with focus on studies from the last decade
Authors: Quante Markus , Hanf Franziska S. , Bär Friederike , Boettcher Marita , Burgemeister Finn , Grawe David , Hoffmann Peter , Schlünzen Heinke
Published: June 2022

Changing land surfaces can have a profound impact on local and regional climates. Cities in particular are associated with a comprehensive transformation of the local surface structure, which, in combination with anthropogenic emissions of radiative active gases and particles, leads to a significant modification of the energy balance of the urban boundary layer. One of the most well-known urban climate phenomena is the urban heat island effect. In addition to the thermodynamic effect, a clear urban influence on the wind field and the modification of precipitation above and around cities is documented by many studies. Observational and modeling studies provide convincing evidence that precipitation patterns over and/or around urban areas are altered, and convective precipitation and flash flood events may be enhanced or even triggered. The urban influence often is result of a combination of thermal effects in connection with the heat island, obstacle effects an aerosol influences on microphysical processes and on the heating profile over the city. Precipitation can not only be increased by cities, it can also be weakened or even averted, especially in connection with particle emissions. Inprinciple urban effects on precipitation are fairly well known, but the many published studies on them show a wide range in terms of the magnitude of precipitation changes and their location relative to the urban area. Simple statements concerning urban precipitation modification cannot currently be made, if this is at all possible given the complexity resulting from the overlaying influencing factors. In many cases, the lack of standardized reporting of study results makes it considerably more difficult to compile generalized statements. As part of the Cluster of Excellence "Climate, Climatic Change and Society" (CliCCS), a project is focussing on sustainable adaptation scenarios of cities with regard to hydrological pressures in connection with climate change. Within this project, we conducted a systematic literature review on precipitation modification by cities with a focus on the last 10 years. The reason for this was that the last comprehensive review on the subject was several years ago and the number of publications is constantly increasing. Here we report the first results of our systematic review broken down by spatial scale, dominant processes and possible relevance to climate change. In doing so, we highlight the influence of cities on heavy precipitation and point out the development of the research landscape and alleged research gaps. Selected results from recent publications are shown for illustrative purposes.
Measurement and evaluation of the soil thermal parameters on the surface energy balance in an agricultural plot
Authors: Brut Aurore , De La Rue Du Can Odile , Granouillac Franck , Zawilski Bartosz , Boone Aaron , Canut Guylaine , Lothon Marie , Lohou Fabienne
Published: June 2022

A precise estimation of the surface energy budget is a challenge to better understand, model and forecast both weather and climate, and their dependence on external constraints. However, in the micrometeorology community, it is already well known that the energy balance closure is an issue over many surfaces (Foken, 2008). Previous studies often focused on turbulent fluxes, effects of advection or time averaging for the flux calculation. This study is dedicated to evaluating the accuracy of the ground heat flux, thanks to a field experiment carried out on the ICOS site of Lamasquère (FR-Lam). Both the soil heat flux and storage are often difficult to precisely measure because thermal conductivity and heat capacity are strongly dependent on the very local soil texture (% clay, % sand, % organic matter) and water content. 

The experimental campaign is conducted over a wheat field from autumn 2021 to summer 2022, and heat pulse sensors are installed in various pits to measure thermal parameters (conductivity and heat capacity) at different depths within the ploughing crust. This device currently complements the operational measurements of temperature and soil water content profiles (sensors at 5, 10, 30, 50 and 100 cm), meteorological measurements and turbulent fluxes from an Eddy Covariance set-up.

 In a first step, we will present the results of the sensor measurements for the soil thermal parameters, their local dynamics in relation to the soil parameters, the vegetation development and the weather. Then, using these measurements and the temperature profiles in the soil, we will evaluate the accuracy of the ground heat flux in order to estimate its impact on the closure of the energy balance of vegetated surfaces. These results will be also compared to measurements from self-calibrated heat flux plate and the heat storage in the soil layer above the plate.
Interactions Between the Nocturnal Low-Level Jets and the Urban Boundary Layer: A Case Study over London
Authors: Tsiringakis Aristofanis , Theeuwes Natalie , Barlow Janet F. , Steeneveld Gert-Jan
Published: June 2022

Understanding the physical processes that affect the turbulent structure of the nocturnal urban boundary layer is essential for improving forecasts of air quality and the air temperature in urban areas. Low-level jets have been shown to affect turbulence in the nocturnal urban boundary layer. We investigate the interaction of a mesoscale low-level jets with the urban boundary layer during a 60-h case study. We use observations from two Doppler lidars and results from two high-resolution numerical-weather-prediction models (Weather Research and Forecasting model, and the Met Office Unified Model for limited-area forecasts for the U.K.) to study differences in the occurrence frequency, height, wind speed, and fall-off of low-level jets between an urban (London, U.K.) and a rural (Chilbolton, U.K.) site. The low-level jets are elevated (<span tabindex="0" role="presentation" data-mathml='≈'>≈ 70 m) over London, due to the deeper urban boundary layer, while the wind speed and fall-off are slightly reduced with respect to the rural low-level jets. Utilizing two idealized experiments in the WRF model, we find that topography strongly affects low-level jets characteristics, but there is still a substantial urban influence. Finally, we find that the increase in wind shear under the low-level jets enhances the shear production of turbulent kinetic energy and helps to maintain the vertical mixing in the nocturnal urban boundary layer.

Reference:

Tsiringakis, A., Theeuwes, N.E., Barlow, J.F., GJ. Steeneveld, 2022: Interactions Between the Nocturnal Low-Level Jets and the Urban Boundary Layer: A Case Study over London. Boundary-Layer Meteorol 183, 249–272. https://doi.org/10.1007/s10546-021-00681-7
Constructing Wind Corridor System as a Mitigation Strategy for the Urban Heat Island Effect in Taichung City
Authors: Tsai Pei-Chi , Ou Hsing-Yu , Chang Chou-Tsang , Lin Tzu-Ping
Published: June 2022

High-density development has reduced greenery and water coverage, thus reducing the environment's ability to regulate temperature. Temperatures in urban areas are significantly higher than in suburban areas, resulting in severe heat island effects. The urban heat island intensity in many cities in Taiwan is generally higher than 2.5°C in summer. One of the causes is the poor ventilation of dense buildings. Therefore, the construction of wind corridor systems based on the current urban conditions is an excellent way to improve the quality of heat dissipation.

The paper first reviews the definition of a wind corridor system and introduces the existing urban cases. Afterwards, the long-term climate data provided by the National Science and Technology Center for Disaster Reduction and the Taiwan Climate Change Projection Information and Adaptation Knowledge Platform, the High-Density Street-Level Air Temperature Observation Network data from the Building and Climate Laboratory of National Cheng Kung University, and the overlay of Landsat satellite computer visual and cadastral map data are used. The data were combined to investigate the appropriate hierarchical structure of the wind corridor systems in Taichung City.

A Natural Wind Corridor is the long-term natural wind trend mapped from the data mentioned above. Then, based on the Natural Wind Corridor, the Urban Wind Corridor System at the height of 2 metres is constructed by the Least-Cost Path (LCP) analysis with roughness length grids. Implementing the Urban Wind Corridor at different scales, such as in urban and local areas, is discussed. We defined that wind passage is facilitated when the roughness length is less than 1 metre, and the path is allowed to deflect in advance when it encounters large areas of high roughness length (over 2 metres). The deflection angle should not exceed 30°. To define the Primary and Secondary Wind Corridor, we calculate the number of high-roughness-length grids that each route passes through. Wind corridors are classified as Type II when the grid amount of the route passing through, which contains greater than 1 metre in roughness length, is between 35% and 50% of the study domain. If this value is less than 35%, the wind corridor is classified as Type I.

Besides, the Computational Fluid Dynamics (CFD) simulation was used to verify the effectiveness of the heat mitigation strategies and provide recommendations on implementation methods, such as limiting the minimum site ventilation ratio by area.

We found that the LCP analysis has the advantage of being fast and less costly, but it also limits the results, e.g., the exclusive starting wind direction limits the interpretation. We suggest that supplementary conditions can be set for the difference in the nature of upwind and downwind areas.
Kalman Filter Post-Processing of the Wind Speed and Gusts NWP and Analog-Based Forecasts: Performing Sensitivity Tests
Authors: Vujec Ivan , Odak Plenković Iris
Published: June 2022

Weather forecasting is based on the NWP models for a long time. Although their skill is constantly improving, their limitations are still substantial. This is especially the case in the complex terrain, even when referring to the high-resolution mesoscale models. Besides, NWP models require massive computational resources, and their requirements grow excessively with the refinement of the spatiotemporal scale. Thus, in addition to the further model development, the forecast improvement can be obtained by statistical post-processing of raw NWP forecasts for the locations where measurements are available. The post-processing methods analyzed in this work are based on the analog and Kalman filter (KF) approach. 

The focus of this study is to perform a sensitivity test to find the optimal value of the variance ratio r in the KF algorithm for different forecasts. The KF algorithm is applied to generate four different forecasts: KF (KF applied to the raw NWP time-series), KFAN (KF applied to the analog-method time-series), KFAS (KF applied to NWP forecasts in analog space), and KF-KFAS (KF applied to the KFAS time-series). The post-processing is applied to the point-based predictions of wind speed and wind gust. The forecasting range is 72 hours, and the measurements include 61 locations across the Republic of Croatia.  

The wind forecasts are analyzed considering the variables as both continuous and categorical. The continuous verification relies on RMSE decomposition, spectral analysis, and quantile-quantile plot. The categorical verification includes the equitable threat score, frequency bias measure, extremal dependence index, and frequency measure. The verification is conducted to assess the improvement for both the overall data and for the relatively extreme events. The results suggest that for the KF and KFAS forecasts the r-value of 0.01 is recommended, whereas for the KFAN and KF-KFAS forecasts the r-value should be set to 0.001. Even though different r-value implementations yield certain trade-offs, the proposed r-values are considered optimal since they lead to excellent results for the overall data, and the results remain adequate even for strong wind. 
Perceptions of impact-based warning information for ice-throw risk: A Norwegian survey 
Authors: Jeuring Jelmer , Sivle Anders
Published: June 2022

Risk management for wind farms has become more standardized in terms of calculating acceptable risk criteria, but so far the communication of possible risks and their consequences for societal actors has not evolved into a validated set of best practices. The current state of knowledge about best practices for ice throw/fall risk communication is still in an exploratory phase, and empirical research on this is fragmented. The main attempt toward a consolidation of best practices in ice throw/fall risk communication has been part of the IEA Wind TCP Task 19 work. Its mandate is to provide international guidelines for ice risk assessment. A report that was published in 2018 (Krenn et al., 2018) is currently being updated. The work reported in this presentation is part of the project ‘Wind Energy in Icing Climates’, funded by the Norwegian Research Council and wind farm operators in Norway. The Norwegian Meteorological Institute has executed a national survey with the specific aim to develop recommendations for communication of the risk of ice throw from turbines in Norwegian wind farms. The survey aimed at getting insight into perceptions of the general public in Norway about ice-throw risk, and the perceived value of different communication tools and formats of ice-throw risk information for Norwegian wind farms. We discuss findings on a range of topics, including people’s familiarity with wind turbine parks, their weather risk information seeking patterns, people’s understanding of impact-based warnings for ice-throw risk, and their behavioural capacity to mitigate possible negative impacts emerging from ice throw risks. Based on the survey findings, we provide a systematic set of recommendations regarding communication and formatting of ice throw risk warning information.
Large-Eddy Simulation Subgrid Scale Modelling using Artificial Neural Networks
Authors: Stoffer Robin , van Leeuwen Caspar , Podareanu Damian , Codreanu Valeriu , Veerman Menno , Janssens Martin , Hartogensis Oscar , van Heerwaarden Chiel
Published: June 2022

Large-eddy simulation (LES) is an often used technique to simulate atmospheric boundary layers. In LES, the effects of the unresolved turbulence scales on the resolved scales have to be parameterized with subgrid scale (SGS) models. These SGS models usually require strong assumptions about the relationship between the resolved flow fields and the terms correcting for the unresolved physics, which are often violated in reality and potentially hamper their accuracy. Also, they tend to interact with the discretization errors introduced by the popular LES approach where a staggered finite-volume grid acts as an implicit filter.

We therefore developed an alternative LES SGS model based on artificial neural networks (ANNs) that allows to compensate for both the unresolved physics and instantaneous spatial discretization errors associated with a staggered finite-volume grid, without the need for strong assumptions. To this end, we used a test case of turbulent channel flow (with friction Reynolds number Reτ=590) simulated with the computational fluid dynamics code MicroHH (v2.0). We trained the ANNs based on instantaneous flow fields from a direct numerical simulation (DNS) of the selected channel flow. By applying an explicit spatial filtering procedure on the high-resolution DNS fields, we generated millions of samples to train the ANNs in a supervised manner.

In general, we found that the ANNs were well able to predict the correct values for flow fields not seen during training. In addition, our ANN SGS model was able to generalize towards multiple coarse horizontal resolutions, in particular when these resolutions were located within the range of the training data. This shows that ANNs have potential to construct highly accurate, generalizable SGS models. Several open challenges do remain though before this potential can be successfully leveraged in actual LES applications: we observed an artificial build-up of turbulence kinetic energy when we directly incorporated our ANN SGS model into a LES simulation of the selected channel flow, eventually resulting in numeric instability. We hypothesize that error accumulation and aliasing errors were both important contributors to the observed instability.
Grid Refinement in ICON
Authors: Zängl Günther , Reinert Daniel , Prill Florian
Published: June 2022

We describe the implementation of grid refinement in the atmosphere component of the ICOsahedral Nonhydrostatic (ICON) modeling system. It basically follows the classical two-way-nesting approach known from widely used mesoscale models like MM5 or WRF, but differs in the way how feedback from fine grids to coarser grids is applied. Moreover, the ICON implementation supports vertical nesting in the sense that the upper boundary of a nested domain may be lower than that of its parent domain. Compared to the well-established implementations on quadrilateral grids, new methods had to be developed for interpolating the lateral boundary conditions from the parent domain to the child domain(s) on triangular grids. These are based on radial basis functions (RBFs) and partly apply direct reconstruction of the prognostic variables at the required grid points, whereas gradient-based extrapolation from parent to child grid points is used in other cases. The technical implementation on the unstructured ICON grid is based upon sorting the boundary interpolation points at the beginning of the grid-point index vector, so that computations on boundary interpolation points can be excluded by appropriate start indices without the need of IF masks. The run-time flow control is written such that limited-area domains can be processed identically to nested domains except for the lateral boundary data supply. 

To demonstrate the functionality and quality of the grid nesting in ICON, we present idealized tests based on the Schär mountain wave test case (Schär et al., 2002) and the Jablonowski-Williamson test case (Jablonowski and Williamson, 2006). The results show that the numerical disturbances induced at the nest boundaries are small enough to be negligible for real applications. This is confirmed by experiments closely following the configuration used for operational numerical weather prediction at DWD, which demonstrate that a regional refinement over Europe has a significant positive impact on the forecast quality in the northern hemisphere.

 

References

Schär, C. and D. Leuenberger and O. Fuhrer and D. Lüthi and C. Girard: A new terrain-following vertical coordinate formulation for atmospheric prediction models, Mon. Weather Rev., 130 , 2459-2480, 2002.

Jablonowski, C. and D.L. Williamson: A baroclinic instability test case for atmospheric model dynamical cores, Q. J. Roy. Meteor. Soc., 132, 2943-2975, 2006.

 
Observations of turbulence properties in coupled and decoupled stratocumulus-topped marine boundary layers
Authors: Nowak Jakub L. , Siebert Holger , Szodry Kai-Erik , Malinowski Szymon P.
Published: June 2022

Wide-spread presence, persistence and high albedo of marine stratocumulus clouds makes them important for the energy balance of the planet, hence also in model-based climate predictions. Typically, stratocumulus clouds occupy upper few hundred meters of the atmospheric boundary layer which is commonly referred as stratocumulus-topped boundary layer (STBL). The transport of moisture from the ocean surface maintains the cloud against entrainment drying from the free toposphere. When the STBL grows in depth, the drivers of the circulation weaken or the subcloud layer stabilizes, then the mixing of air volumes across the entire STBL depth may become impossible to sustain - the boundary layer decouples.

Within the present study, the stratification and turbulence properties in coupled and decoupled marine STBL are compared using high resolution in situ measurements performed by the helicopter-borne platform ACTOS in the region of the Eastern North Atlantic. Particular attention is given to small-scale turbulence.

The coupled STBL was characterized by a comparable latent heat flux at the surface and in the cloud top region, and substantially smaller sensible heat flux in the entire depth. Turbulence kinetic energy (TKE) was efficiently generated by buoyancy in the cloud and at the surface, and dissipated with comparable rate across the entire depth. Structure functions and power spectra of velocity fluctuations in the inertial range were reasonably consistent with the predictions of Kolmogorov theory. The turbulence was close to isotropic.

In the decoupled STBL, decoupling was most obvious in humidity profiles. Heat fluxes and buoyant TKE production at the surface were similar to the coupled case. Around the transition level, latent heat flux decreased to zero and TKE was consumed by weak static stability. In the cloud top region, heat fluxes almost vanished and buoyancy production was significantly smaller than for the coupled case. TKE dissipation rate inside the decoupled STBL varied between its sublayers. Structure functions and power spectra in the inertial range deviated from Kolmogorov scaling. This was more pronounced in the cloud and subcloud layer in comparison to the surface mixed layer. The turbulence was more anisotropic than in the coupled STBL, with horizontal fluctuations dominating. The degree of anisotropy was largest in the cloud and subcloud layer of the decoupled STBL.

Integral length scales were of the order of 100 m in both cases which is smaller than the depth of the coupled STBL or of the sublayers of the decoupled STBL. It may be speculated that turbulence produced in the cloud or close to the surface is redistributed across the entire coupled STBL but rather only inside the sublayers where it was generated in the case of the decoupled STBL.
Sensitivity of the Nocturnal and Polar Boundary Layer to Transient Phenomena
Authors: Kaiser Amandine , Vercauteren Nikki
Published: June 2022

Atmospheric boundary layers with thermally stable stratification (SBL) are the least understood type of boundary layer due to suppressed turbulence and the presence of myriads of processes on multiple spatio-temporal scales that modulate the turbulence. Classical approaches to turbulence parameterization fail to reproduce turbulent dissipation in SBL contexts and this is a known source of errors in weather and climate models.

One of the research challenges is to develop an accurate representation of distinct regimes of the SBL and transitions between them. Defining all mechanisms which lead to these sudden regime transitions and predicting or detecting them is still a challenge. Stochastic modeling approaches are a promising framework to analyze the different types of triggers for regime transitions. Therefore, we test the sensitivity of the SBL to intermittent turbulence mixing events by extending a single-column model with physically meaningful randomizations. Noise in the boundary conditions for example represents fluctuating geostrophic wind or cloud cover. This model is used as a numerical tool to systematically investigate noise-induced regime transitions of the SBL.

The overall objective is to improve the representation of the atmospheric boundary layer in numerical weather prediction and climate models by developing stochastic parametrization concepts. It is very useful to identify abrupt regime transitions in order to anticipate air pollution hazards, fog, and frost, all of which coincide with the onset of a very stable boundary layer. In addition, current SBL parametrizations fail at representing mixing in the very stable regime and may need to switch to a parametrization where turbulence stationarity assumptions are relaxed.
Gender inequalities in heat-related mortality in the Czech Republic, 1995-2019
Authors: Vésier Chloé , Urban Aleš
Published: June 2022

Because of climate change, summer temperatures are predicted to rise and heat waves to be more recurrent, including in Central Europe. It is important to understand heat-related risks on human mortality and to identify inequalities in vulnerability among the population, such as sex and gender inequalities. In this study, the associations between daily temperature and mortality during the five warmest months of the year (from May to September) have been analysed in the Czech Republic for the period 1995–2019. The primary focus of the analysis was on the differences in the associations by sex, i.e., between men and women. These two categories were further divided by age, marital status, residence’s location and cause of death. Mortality time series have been modelled by a quasi-Poisson regression model with a distributed lag non-linear model (DLNM) to account for the delayed and non-linear effects of temperature on mortality. The heat-related mortality risks obtained in each population group were expressed in terms of risk at the 99th percentile of summer temperature relative to the minimum mortality temperature.

The results showed that women were more at risk to die because of heat than men. With regard to age, the highest risk for men was observed between 75 to 84 years old, while risk for women was higher for women above 85 years old. Risks among married people were lower than risks among single, divorced and widowed people, and risks in divorced women were significantly higher than in divorced men. Thus, this study showed that social and demographic criteria impacted the heat vulnerability and in particular, results highlighted the important role of sex and gender inequalities in heat-related mortality. Deeper studies on these social drivers would be relevant to design efficient and fair mitigation and adaptation strategies.
The place beyond the lines - Efficient storage allocation in a spatially unbalanced power system with a high share of renewables
Authors: Czock Berit , Sitzmann Amelie , Zinke Jonas , Fiedler Stephanie
Published: June 2022

In electricity grids with high shares of solar and wind, storage technologies, such as electric batteries, are suitable to complement renewable generation. Renewable generation is unequally distributed both temporally and spatially. Storage can offset the temporal volatility of wind and photovoltaic (PV) by shifting generation or load if it they do not coincide temporally. In Germany, the power system is additionally affected by a spatial mismatch between load and renewable generation. While wind power generation is predominantly located in the North of Germany, demand is centred in the more densely populated West and South.  Due to insufficient transmission capacity, North-South transmission lines are frequently overloaded in situations with high wind generation. As a result, wind generation is curtailed while fossil fired generation is used to supply loads south of the transmission bottleneck, thus jeopardizing German efforts to increase renewable generation and reducing greenhouse gases. Installing storage capacities can address this spatial mismatch to achieve a more balanced transmission line utilization, thus increasing overall transmission grid utilization, decreasing curtailment and reducing the use of fossil-fuel combustion.  To do so, the allocation of storage within the electricity grid is critical. To investigate the relationship between storage, renewable generation, and the transmission grid, we employ a linear optimization model that allows to analyse optimal allocation of storage and generation technologies within Germany. Our model simulations use high resolution reanalysis meteorological data from the COSMO-REA6 data set developed by the Hans-Ertel-Centre for Weather Research, Climate Monitoring and Diagnostics, and a detailed depiction of electricity grid constraints of Germany. We find that an allocation of storage close to grid bottlenecks is optimal to facilitate wind generation replacing fossil fired generation, thus making efficient use of renewable generation. If grid bottlenecks are not accounted for in the storage allocation, storage cannot be used to relieve grid congestion. Consequently, we find an increase of up to 10% in the overall system operational costs and higher curtailment rates for wind and solar power compared to having storage installed at optimal locations.
The Ruisdael Observatory: advancing atmospheric science in the Netherlands
Authors: Russchenberg Herman , Apituley Arnoud , Holzinger Rupert
Published: June 2022

As of  2018 the atmospheric research community in the Netherlands, including universities, agencies and institutes, joined forces in the Ruisdael Consortium, named after the 17th century painter who depicted the skies over Holland with a realistic interplay of light, clouds, and the land surface. The consortium centres its activities around the combined use of experimental facilities and model development, aiming at better forecasts of the weather and air quality, as well as getting deeper insights into climate processes. While the driving force behind the consortium results from the urge to advance science, the societal spin-off is hard to neglect. The observational data as well as the high resolution models increasingly find their use in industrial applications such as the generation of sustainable energy, or the evaluation of air quality in urban areas. The Ruisdael Consortium acts as an agenda setting body in the atmospheric sciences, and contributes to the long term strategy of science in the Netherlands, and with its combination of academia, applied institutes and agencies it embodies a direct link between education, research, application and public outreach.

Selected examples of the Ruisdael activities are

Coordinated actions in Amsterdam to study the urban climate for improving climate adaptation strategies in cities,

Studies in Rotterdam of the interplay between climate change and potentially enhanced virus outbreaks,

Fine weather forecasts for the wind and solar energy production.

With the Ruisdael stations currently confined to land, plans are being developed to install additional station on the North Sea, making use of the proliferation of wind farms in a co-creative setting of the scientific and industrial communities.