bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlled-release testing of the static chamber methodology for direct measurements of methane emissions
Authors: Williams James P. , El Hachem Khalil , Kang Mary
Published: July 2023

Abstract. Direct measurements of methane emissions at the component level provide the level of detail necessary for the development of actionable mitigation strategies. As such, there is a need to understand the magnitude of component-level methane emission sources and to test methane quantification methods that can capture methane emissions at the component level used in national inventories. The static chamber method is a direct measurement technique that has been applied to measure large and complex methane sources, such as oil and gas infrastructure. In this work, we compile methane emission factors from the Intergovernmental Panel on Climate Change (IPCC) Emission Factor Database in order to understand the magnitude of component-level methane flow rates, review the tested flow rates and measurement techniques from 40 controlled-release experiments, and perform 64 controlled-release tests of the static chamber methodology with mass flow rates of 1.02, 10.2, 102, and 512 g h−1 of methane. We vary the leak properties, chamber shapes, chamber sizes, and use of fans to evaluate how these factors affect the accuracy of the static chamber method. We find that 99 % of the component-level methane emission rates from the IPCC Emission Factor Database are below 100 g h−1 and that 77 % of the previously available controlled-release experiments did not test for methane mass flow rates below 100 g h−1. We also find that the static chamber method quantified methane flow rates with an overall accuracy of +14/-14 % and that optimal chamber configurations (i.e., chamber shape, volume, and use of fans) can improve accuracy to below ±5 %. We note that smaller chambers (≤20 L) performed better than larger-volume chambers (≥20 L), regardless of the chamber shape or use of fans. However, we found that the use of fans can substantially increase the accuracy of larger chambers, especially at higher methane mass flow rates (≥100 g h−1). Overall, our findings can be used to engineer static chamber systems for future direct measurement campaigns targeting a wide range of sources, including landfills, sewerage utility holes, and oil and natural gas infrastructure.
Improving Communication Between Meteorologists and Oceanographers: The American Meteorological Society’s Committee on Oceans, Coasts and the Blue Economy
Authors: Emch Pamela
Published: July 2023

The atmosphere and oceans are an inter-connected part of the larger Earth geophysical system and the associated scientific disciplines and the individuals involved in those disciplines could potentially benefit from improved opportunities for interaction and collaboration. 
The American Meteorological Society (AMS) has long had a goal of strengthening ties with the oceanography community above and beyond those engendered in long-standing existing AMS committees. There are several committees with the AMS STAC (Scientific and Technological Activities Commission) that deal partly with oceanographic/sea/coastal topics, however, it was thought that a new committee could be created to span a different and often broader space, focusing on communication, decision support and economic aspects as well as geophysics. Therefore, in Fall 2020 the AMS initiated a new Ad Hoc / Temporary Committee:  the Ad Hoc Committee on Oceans, Coasts and the Blue Economy. This became a permanent committee of the AMS in September 2022.
The overall objective of the Committee on Oceans, Coasts and the Blue Economy is to promote collaboration, bring together stakeholders, elicit input, and coordinate community feedback regarding atmospheric, oceanographic, and economic connectivity.  In addition, the committee seeks to  educate stakeholders on respective information needs, operational requirements and constraints, and current capabilities and emerging technologies that could be used to improve decision-making.  The topics of interest can be relatively wide-ranging, such as outreach to the broader maritime user community, maritime transportation, strategic initiatives that involve the broader weather, water and climate enterprise, and decision support.  
The Committee on Oceans, Coasts and the Blue Economy has thus far primarily focused on organizing sessions in conferences and symposia that stimulate and support information exchange by providing opportunities for the weather, water, climate, and oceanographic stakeholders to interact and discuss topics of mutual interest.  While it has been successful, especially for a relatively new committee, challenges remain.  This presentation will provide a summary of the committee, its successes, challenges, and future plans.
Bioclimate conditions in SW Greenland in the second half of the 18th century
Authors: Chmist Konrad , Araźny Andrzej , Przybylak Rajmund , Wyszyński Przemysław , Singh Garima
Published: July 2023

The bioclimate in SW Greenland was estimated using two existing series of meteorological observations from stations located in this area: Neu-Hernhut (1st Sep 1767 – 22nd Jul 1768) and Godthab (Jan 1790 – Jun 1792). The first series is the oldest available long-term series of instrumental measurements for this region. Observations of air temperature, atmospheric pressure, and wind direction and force were made twice a day by Christopher Brasen (1738–74) at 8 a.m. and 2 p.m. The second series of measurements covers the period Jan 1784 – Jul 1792, but the lack of bioclimatic utility of the data (the frequent absence of the required wind speed data) limited its use to only the aforementioned 2.5 years. Observations were carried out in accordance with the instructions used by members of the Meteorological Society of the Palatinate, which also provided the necessary tools. Measurements were taken three times a day by the Danish Reverend Andreas Ginges (1754–1812), at 7 a.m., 2 p.m. and 9 p.m. These were included in a manuscript titled Astronomiske og meteorologisk Iagttagelser, anstillede i Godthaab i Grønland 1782–1792 (Det Kgl. Bibliotek in Copenhagen).
In order to present the bioclimatic conditions in this part of Greenland, the following indices and indicators were used: Wind Chill Temperature (WCT), Insulation Predicted (Iclp), and day-to-day changes in air temperature and atmospheric pressure. The obtained results were compared with contemporary conditions (1991–2020).
Wind Chill Temperature values in the 1789–92 expedition years were lower than at present. In the period January–June of the 1767–68 expedition, the threat to human health was less than at present (by 1.7 °C). For a man in motion (metabolism = 135 Wm-2) the meteorological conditions of SW Greenland show that the required clothing insulation in 1791–92 (Jan–Jun) was similar to the modern period. During 1789–92, an increase of 0.1 clo in the clothing insulation required to obtain thermal comfort was recorded, while in 1767–68, there was a decrease (of 0.2 clo) relative to the period 1991–2020. Day-to-day variation in atmospheric pressure in the category of strong (8–12 hPa) and very strong stimuli (>12 hPa) most often occurred in the winter and spring months. Under this criterion, the expeditions of 1767–68 and 1789–90 were felt more strongly than in the modern period. During the four historical expeditions in the 18th century, there was found, among other things, a slight increase (1–5%) in frequency of occurrence of significant (4–6 °C) and severe stimuli (> 6 °C) according to the day-to-day variation of average diurnal air temperature, as compared against the contemporary period.
The work was supported by the National Science Centre, Poland project No. 2020/39/B/ST10/00653.
PM10 and PM2.5 prediction in Seoul, South Korea using LDAPS meteorological data and tree-based machine learning
Authors: Kim Bu-Yo , Lim Yun-Kyu , Cha Joo Wan
Published: July 2023

Particulate matter (PM) increases traffic accidents and mortality rates in the short term, and poses a long-term threat to public health, such as cardiovascular and respiratory diseases, deteriorating human health. Therefore, real-time monitoring and prediction are crucial for improving air quality, and efforts should be made to regulate and reduce the emissions of air pollutants at the national or regional level. In this study, tree-based machine learning algorithms (RF, XGB, LGB) were used with local data assimilation and prediction system (LDAPS) meteorological forecast data (four times a day, hourly forecast for 36 hours) to predict PM10 and PM2.5 in Seoul, South Korea. Seoul, being a densely populated megacity, experiences high local emissions of air pollutants and significant influx of high-concentration pollutants from neighboring countries and desert areas. Therefore, monitoring and prediction of PM concentrations are of utmost importance in Seoul. The prediction results were compared with the observed data of PM10 and PM2.5 from air-quality measurement station in Seoul. The results showed that LGB method among the tree-based ML algorithms was the most suitable for PM prediction, with hourly R2=0.83~0.86 and daily R2=0.996. These results showed that the prediction performance was significantly higher than the chemical transport model prediction results, with R2 being more than 0.2 higher, and the prediction performance was superior especially in cases of high-concentration PM. Therefore, the high-accuracy PM prediction based on machine learning presented in this study can be useful for air quality monitoring and improvement.
 
Acknowledgments: This work was funded by the Korea Meteorological Administration Research and Development Program “Research on Weather Modification and Cloud Physics” under Grant (KMA2018-00224).
The new-high resolution HYRAS global radiation dataset for Germany and its river catchments
Authors: Brendel Christoph , Rauthe Monika , Deutschländer Thomas
Published: July 2023

Within the research program BMDV Network of Experts of the Federal Ministry for Digital and Transport, the Hydrometeorological raster datasets (HYRAS) of the Deutscher Wetterdienst (DWD) have been extended by one variable: the global radiation. Previously, precipitation, temperature (daily mean, maximum, minimum), and relative humidity data were available, covering Germany and its river catchments from 1951- 2020 with a spatiotemporal resolution of 5km x 5km and 1 day.
The HYRAS datasets are frequently used in various applications, such as analyzing current and historical climate conditions, as well as for the adjustment of the bias in climate model data which results in more accurate climate change impact assessments. Another application of the HYRAS datasets is the usage as input data for a water balance model. Since global radiation is an important parameter to correctly model evapotranspiration, together with the other HYRAS variables, the global radiation leads to more realistic results of the long-term development of the modeled runoff as well as high-flow and low-flow situations in river basins. Therefore, a gridded dataset of global radiation should extent as far back into the past as possible to include trends and decadal variability.
The interpolation methodology and the availability of suitable measurement data have a significant impact on data quality and thus the suitability of the gridded dataset for the aforementioned applications. Station measurements of global radiation are available only very sporadically for the period 1951-1980 for Germany and its river catchments, especially at the very beginning of the time series. Thus, station measurements of sunshine duration were also considered to interpolate the HYRAS global radiation dataset. These measurements are widely available and cover the entire area, making them a valuable resource for the interpolation. To convert the sunshine duration measurements into global radiation, a simple linear regression method according to Angstrom and Prescott can be used, which shows good results for monthly but not for daily values. Especially a large bias for low global radiation values is caused by using the simple linear regression. To improve the quality of this method the total column cloud liquid water content from ERA5 reanalysis data has been implemented as additional predictor. 
After a short overview about dataset generation, a comparison between the new HYRAS global radiation dataset, station measurements of global radiation and further reference datasets like the ERA5 reanalysis and the CM SAF SARAHv2.1 satellite dataset will be presented. 
Plume rise model for merging plumes
Authors: Ferrero Enrico , Tenti Bianca , Alessandrini Stefano
Published: July 2023

To correctly reproduce the dispersion of pollutants the plume rise modeling is fundamental to obtain the injection height, i.e. the altitude at which the majority of the smoke burden is released into the surrounding atmosphere, because from this depends how the plume from fire emissions are ultimately transported In 2013 Alessandrini et al. proposed a method for the buoyant plume rise computation in which a scalar transported by the particles and representing the temperature difference between the plume and the environment air is introduced. As a consequence, no more particles than those inside the plume have to be released to simulate the entrainment of the background air temperature. A second scalar, the vertical plume velocity, is assigned to each particle. In this way the entrainment is properly simulated and the plume rise is calculated from the local property of the flow. However, the method may have some drawbacks when two plumes from different sources cross, as in the case of two neighbouring chimneys or scattered fires. In this case, the scheme can lead to non-physical situations that lead to an increase in temperature. To avoid this problem, the scheme has been modified. In the new model, the particles do not carry the temperature difference but the temperature and mass so that the transport of the heat quantity can be simulated. The model is  tested against data from two laboratory experiments in neutral and stable stratified flows. The comparison shows a good agreement. Then, we teste the model in the case  of two plumes from adjacent stacks combining during the rising stage. The results are presented in terms of statistical indeces and plots.
Assessment of forecast skill of seasonal forecasts with the hydrologic model ParFlow/CLM to predict subsurface water resources under atmospheric drought conditions in central Europe
Authors: Belleflamme Alexandre , Goergen Klaus , Hammoudeh Suad , Wagner Niklas , Kollet Stefan
Published: July 2023

The repeated and severe droughts that have affected central Europe over the last years (2018, 2019, 2020, 2022) have triggered the need for sub-seasonal to seasonal forecasts of subsurface water resources. Such long-term forecasts are needed in several sectors such as agriculture, forestry, and water resources, to allow for elaborating and implementing management strategies able to deal with the reduced water resources.
In this context, we have developed a high-resolution (0.6km) monitoring and forecasting system of the terrestrial water cycle with the integrated, physics-based hydrologic model ParFlow/CLM over Germany and the surrounding regions. This model setup simulates the surface and 3D subsurface state and fluxes down to 60m depth, thereby covering the variably saturated zone as well as the saturated zone of shallow groundwater bodies. We use the seasonal 50-member ensemble forecast SEAS from the European Centre for Medium-Range Weather Forecasts (ECMWF) as atmospheric forcing for ParFlow/CLM. We calculate these forecasts over the whole available lead time, i.e., seven months, at the beginning of each meteorological season (March, June, September, and December).
In this study, we analyse the ability for the ParFlow/CLM seasonal forecasts to predict the evolution of water resources, and in particular total subsurface storage, water table depth, and groundwater recharge, during the summer drought of 2022. To evaluate the forecasting skill, the 50-member ensemble seasonal forecasts are compared with a reference time series simulated by forcing ParFlow/CLM by the first 24h of each daily HRES deterministic forecast from ECMWF, which has been validated against observations in a previous study.
Finally, we provide some examples on how these seasonal forecasts can be synthesized to assess the risk of water resources depletion due to atmospheric drought conditions, thus providing useful information for society, and, in particular, the agricultural, forestry, and water management sectors.
Links between major heat waves, drought, and atmospheric circulation in Central Europe
Authors: Bešťáková Zuzana , Lhotka Ondřej , Kyselý Jan
Published: July 2023

Heat waves and drought are phenomena associated with large negative impacts on society and the environment. Their common features include increasing frequency and intensity in recent decades in many regions of Europe, as well as the interconnectedness of the factors that contribute to their development. In this study, we compare the long-term changes in the characteristics of major heat waves and severe drought in Central Europe (during the vegetation period (April-September)), examine the temporal and causal relationships between the two phenomena, their spatial and temporal scales, and the connection with atmospheric circulation. Based on E-OBS (daily temperature and precipitation) data since 1950 for the vegetation period (April-September), drought is characterized by the difference between potential evapotranspiration and precipitation, while heat waves are defined as periods of large positive anomalies of daily temperatures from the mean annual cycle affecting a large area. Heat waves occurring in early/late vegetation period are referred as warm spells due to their lower absolute temperatures and possibly different circulation mechanisms. We use the Jenkinson classification of daily sea level pressure fields from the NCEP/NCAR reanalysis to describe the atmospheric circulation. Circulation types with significantly increased frequency during periods of major heat waves/warm spells and droughts are identified, and changes in their occurrence are studied. We also focus on differences between the early (April-June) and late (July-September) parts of the vegetation period. The analysis contributes to a better understanding of the interrelationships between drought, heat waves, atmospheric circulation and other driving mechanisms during 1950–2019 in Central Europe.
Local polynomial regression-based evaluation of general circulation models regarding teleconnections in boreal wintertime
Authors: Kristóf Erzsébet
Published: July 2023

General circulation models (GCMs) are effective tools to simulate the climate system and to assess its changings. Since large-scale atmospheric teleconnections are the imprints of the internal variability of the climate system, the evaluation of the GCMs concerning teleconnections became an important task in the field of climatology. Previously, a negative extrema-based method was applied on gridded 500 hPa geopotential height time series in the boreal wintertime. First, the Pearson correlations were calculated between all time series. Then, the strongest negative correlation was selected in each grid cell. Finally, the pairs of grid cells were selected which have the same associated negative correlation values. Based on the ECMWF’s ERA-20C and the NCEP/NCAR Reanalysis 1 datasets, it was found that, these pairs of grid cells are mostly located in a north‑south direction, surrounding the Northern Hemisphere in two belts. This means that the geopotential height in the two belts changes simultaneously in opposite directions. The two belts were represented by local polynomial regression (LOESS) curves. It was pointed out that the two belts can be detected in the first realizations of all available historical GCM outputs of the Coupled Model Intercomparison Project Phase 5 (CMIP5), but the courses of the LOESS curves were not captured well by some of the GCMs compared to the reanalyses, especially in case of the southerly located belt. However, different GCM realizations may produce significantly different LOESS curves. Therefore, the aim of this study is to quantify the differences of the LOESS curves obtained from multiple realizations of the GCMs disseminated by the Coupled Model Intercomparison Project Phase 6 (CMIP6). The future goal is to use LOESS curves to detect changes in the climate system, i.e. shifts of the oppositely varying belts.
EURO1k: A high-resolution European weather model developed by Meteomatics
Authors: Pasquier Julie Thérèse , Rausch Johannes , Umek Lukas , Schluchter Christian , Schlauch Alexander , Fengler Martin
Published: July 2023

Accurate and precise weather forecasting is essential for a wide range of applications and industries, from agriculture to transportation to renewable energy. However, current weather models often struggle to represent atmospheric processes accurately due to limitations in spatial resolution. To fill this gap, Meteomatics has developed the EURO1k model, the first pan-European weather model with a spatial resolution of 1 km.
The EURO1k model grid covers 4250 x 4580 km and is run in a rapid-update setup with 24 initializations per day, each run with a lead time of 24 hours. It is based on the Weather Research and Forecasting (WRF) model and uses global ECMWF-IFS model data for boundary conditions. In addition to standard data sources such as weather stations, radar and satellite data, and radiosondes, the EURO1k model also assimilates data from a network of Meteodrones, unmanned aircraft systems (UAS) developed by Meteomatics which collect vertical atmospheric profiles up to 6000m in altitude.
The high spatial and temporal resolution of the EURO1k model allows to accurately represent small-scale weather patterns, resulting in highly accurate and precise forecasts. Indeed, statistical analyses of EURO1k model output against observations from 5000 weather stations in Europe demonstrate increased accuracy compared to other global and regional models. This has important implications for industry and the public. The EURO1k model improves the forecasting of extreme weather events, allowing for better preparation and response. It also enhances the prediction of renewable energy production, thereby improving their cost efficiency and accelerating the energy transition. And, most importantly, it provides a more accurate and reliable weather forecast for communities across Europe. Overall, the EURO1k model represents a major advance in numerical weather prediction, bringing improved understanding and forecasting of the weather to a wide range of users.
Projected near-surface wind speed based on CMIP6 GCMs
Authors: shen cheng
Published: July 2023

Understanding the future changes in global terrestrial near-surface wind speed (NSWS) at specific global warming levels (GWLs) is essential for climate change adaptation. Previous studies have projected NSWS changes, but the changes with different GWLs have yet to be studied. In this paper, we use the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to NSWS changes.
Our results show that NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as GWL increases by 1.5◦C–4.0◦C relative to the preindustrial period, and that these characteristics are more significant with stronger GWLs. The probability density of NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0◦C GWL. Compared to the 1.5◦C GWL, NSWS decreases −0.066m s−1 over NH and increases +0.065m s−1 over SH with 4.0◦C GWL, with the decrease and increase being most significant in East Asia and South America, reaching −0.21 and +0.093m s−1, respectively.
The changes in temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction of Hadley, Ferrell, and Polar cells over NH, and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.
Our study highlights the importance of considering different GWLs when projecting future NSWS changes. It also provides valuable insights into how the changes in temperature gradient and atmospheric circulation induced by global warming affect NSWS changes differently in the two hemispheres, which has important implications for climate change adaptation and mitigation strategies. The results of this study will contribute to a better understanding of the impacts of global warming on wind resources and wind energy production.
A network of stations for long-term evapotranspiration monitoring using the Bowen ratio, eddy covariance, and scintillometer methods in the Czech Republic and Austria
Authors: Orság Matěj , Fischer Milan , Pozníková Gabriela , Eitzinger Josef , Trnka Miroslav
Published: July 2023

Since 2008, a network of weather stations has been gradually built in the Czech Republic (9 sites) and Austria (5 sites) for monitoring evapotranspiration using the Bowen ratio and energy balance method (BREB, 16 units in total), eddy covariance (EC, 5 units), and scintillometers (4 units). The monitoring takes place over diverse agricultural surfaces, such as permanent grasslands, intensively managed arable land, and short-rotation woody coppices. The main focus is put on the seasonal monitoring of turbulent energy fluxes of sensible and latent heat flux, which is further processed as actual evapotranspiration, and usable for water balance analyses, drought monitoring, etc. At selected locations of interest, BREB measurements are combined with EC systems and scintillometers to allow cross-validation of different methods and mutual comparisons as BREB and EC methods determine fluxes within a footprint centered around point measurement in the middle of the field, whereas scintillometer provides an estimation of sensible heat flux integrated over the measurement path length, which is particularly useful in conjunction with remote-sensing products having a coarser resolution, than point measurements. Last but not least, the network serves as a test bed for the development and testing of new approaches to measuring evapotranspiration, i.e. surface renewal/flux variance method. The network is also used to support the Czech drought monitoring system (see www.interdrought.cz) as well as an independent tool for point validation. Due to the long-span dataset gathered, instances of several drought events from selected sites will be presented and analyzed, with the main focus on seasonal actual evapotranspiration during the dry years 2015-2018 at different sites.
Impacts of Soil Moisture Retrievals in the Strongly Coupled Atmosphere-Land Data Assimilation System
Authors: Lim Sujeong , Park Seon Ki , Zupanski Milija
Published: July 2023

Soil moisture is important in a coupled atmosphere-land surface model because it propagates to atmospheric variables such as temperature and water vapor mixing ratio in the planetary boundary layer through the latent and sensible heat fluxes. Therefore, soil moisture observations in a coupled atmosphere-land surface data assimilation system can provide useful information for both the land surface and atmospheric systems. In this study, we assimilate the National Aeronautics and Space Administration’s Soil Moisture Active Passive (SMAP) soil moisture retrievals, which observe the top 5 cm of soil moisture with a global coverage every 2-3 days and a 1000 km swath width. We interface the Maximum Likelihood Ensemble Filter (MLEF) — a hybrid ensemble-variational data assimilation system — with the Noah land surface model with multi-physics options (NoahMP) coupled with the Weather Research and Forecasting (WRF), i.e., developing the WRF-Noah-MP-MLEF system. To assimilate the soil moisture retrievals, the observation processing includes quality control, thinning, bias correction, and horizontal and vertical covariance localization. As a strongly coupled data assimilation system, MLEF assimilates both atmospheric and soil moisture observations — the National Centre for Environmental Prediction (NCEP) Prepared Binary Universal Form for the Representation of meteorological data (PrepBUFR) and the SMAP soil moisture retrievals — and simultaneously corrects the atmospheric and land surface variables. Our results indicate that the WRF-NoahMP-MLEF system improves the soil moisture prediction that provides additional information to the atmospheric variables, especially in the planetary boundary layer, through cross-covariances between land and atmosphere during the summer season. Aiming at developing a triple-coupled data assiilation system for the coupled atmosphere-land-chemistry prediction system, we also preliminary investigate the sensitivity of dust variables propagated from both atmospheric and soil moisture observations in the WRF with Chemistry (WRF-Chem) on an Asian dust event.  
Pacific Walker circulation indices in ERA5 reanalysis
Authors: Kosovelj Katarina , Zaplotnik Žiga
Published: July 2023

The Pacific Walker circulation (PWC) is an integral part of the tropical atmospheric circulation that influences weather patterns globally, including the global distribution of mean precipitation. It also affects the rate of global warming, sea-level rise, and the efficiency of ocean carbon absorption. Due to its importance, many indices have been used historically to quantify the PWC strength and its variability, such as indices based on surface pressure, surface zonal winds, mid-tropospheric vertical velocity and stream function, upper-tropospheric velocity potential, etc.
We reviewed and compared ten different PWC indices for the 1951-2020 period using ERA5 reanalysis data, which is verified against observations.
Our results show good agreement between the time series of normalized indices for annual-mean PWC strength. The exceptions are indices based on 200 hPa velocity potential and 500 hPa stream function. Considering their performance compared to other indices, we explored an alternative definition of the stream-function index and proposed a revised, data-adaptive velocity potential index. Generally, the correlations between the ten indices are high, with the highest correlations between indices based on closely linked physical processes. The largest disagreement between the indices occurs during the strongest El Niños. Therefore, for a robust evaluation of the PWC trends, El Niño events have to be filtered from the time series (as in L’Heureux et al., 2014) and should not coincide with the beginning or the end of the time series. Indices of PWC strength show increasing trends for 1981-2010, mostly neutral trends for the 1951-2020 period, and weak and often insignificant negative trends for the latest 2000-2020 period. PWC trends in ERA5 also hint at a possible multidecadal variability with approximately a 35-year period.
Improvement of numerical simulation of fog: Implementation of a novel scheme in WRF Thompson Aerosol Aware module to simulate the activation of aerosol particles
Authors: Peterka András , Geresdi István
Published: July 2023

Operative forecasting of the fog is still a challenge. The numerical weather prediction (NWP) models frequently miss the spatial and temporal location or onset and the dissipation the fog. Even the recently developed microphysics schemes (e.g. Thompson Aerosol Aware scheme (hereafter TAAS)), evaluate the rate of the activation of the hygroscopic aerosol particles as a function of the vertical velocity. However, in the case of fog, the updraft is usually negligible, therefore this method is physically inconsistent.A novel parameterization technique was developed to evaluate the rate of aerosol activation in fog. This novel scheme was implemented into WRF, TAAS microphysical module. The novel parametrization calculates the activation rate as a function of local cooling rate, and as a function of local change of water vapor content. Furthermore, a diagnostic variable was introduced to evaluate the visibility reduction due to the formation of haze droplets.A well observed radiative fog event was used, to demonstrate the capabilities of the novel parametrization. Data from standard meteorological stations, and a measurement campaign at Budapest are available to test the numerical model.The results are as follows: (i) While the original TAAS activates the aerosols homogeneously throughout the fog (the prescribed minimum value for the updraft velocity is constant in both space and time), the novel parameterization scheme results in significant spatial and temporal variability of the droplets concentration. The impact of the cooling is well demonstrated by the enhanced activation rate at the top of the fog. (ii) In the dissipation period the spatial extension of the fog simulated by novel parameterization fit better to the satellite data than that of calculated by the updraft based parameterization. The novel activation scheme increases the life time of the fog by 30 – 60 min. (iii) Gradual decrease and increase of the visibility can be simulated by calculating of the visibility reduction due to the haze (iv) Comparison of the observed and simulated data shows that the early dissipation of the simulated fog not necessarily the consequence of the overestimation of downward short wave flux.The results of further case studies for different types of fog are planned to present.
Supporting climate risk management with synthetic weather extremes
Authors: Mäkelä Antti , Hukkinen Janne , Pulliainen Jouni , Reinekoski Tapio , Tuomenvirta Heikki
Published: July 2023

Climate change adaptation actions are vital in cities to prepare and adapt to advancing climate change, especially rapidly changing probabilities of extreme weather events. Although especially in Europe many cities have generated adaptation and climate risk management plans and improved decision-support also with respect to weather and climate risks, there is still much to do. Often, risk management actions are strongly activated only after experiencing negative impacts, for example, related to a severe flood causing substantial damages or even losses of lives. In a perfect world, however, in risk management all potential risks should be considered already beforehand, and either adapt to them or at least acknowledge these possible risks.
To support the Finnish cities’ preparedness for possible, yet not previously observed extreme weather events, the project LONGRISK designed a decision platform for strategic risk management, which generated an extensive dialogue between decision-makers and experts in three Finnish pilot cities (Helsinki, Tampere, Kotka). One of the main objectives of the project was to generate a “climate risk monitoring Dashboard” that demonstrates possible near-future extreme weather episodes and their impacts. More specifically, the Dashboard consisted of the synthetic reposition of the Copenhagen 2011 extreme cloudburst over each pilot city including the simulated flood impacts.
The Dashboard was a key tool in persuading city policymakers representing also the highest decision level (e.g. the Mayor) to engage in a Situation Room exercise, i.e., an internal dialogue especially on the possible gaps in their present adaptation level and chain of communication and decision-making. As a result, and especially due to the intensive internal dialogue, the decision-makers recognized their main vulnerabilities and weaknesses and generated a list of action items for further development.
This study presents the overall procedure of generating the Dashboard and running the Situation Rooms. Also, we present the method for generating the synthetic extreme weather events, such as the repositioned Copenhagen cloudburst and related urban flood simulations that are congruent with the climatological statistics and with CMIP6 climate projections.
Advances towards a better prediction of weather extremes in the Destination Earth initiative
Authors: Gascón Estíbaliz , Sandu Irina , Vannière Benoît , Magnusson Linus , Forbes Richard , Polichtchouk Inna , Van Niekerk Annelize , Sützl Birgit , Maier-Gerber Michael , Diamantakis Michail , Bechtold Peter , Balsamo Gianpaolo ,   the ECMWF Destination Earth team
Published: July 2023

Destination Earth – DestinE – is an ambitious initiative of the European Commission, in support of its Digital Strategy and the Green Deal. Bringing together scientific and industrial excellence from across Europe, DestinE will contribute to revolutionising the European capability to monitor and predict our changing planet, complementing existing national (meteorological services) and European efforts (Copernicus services).
Based on the integration of extreme-scale computing, Earth system simulations, and the real-time exploitation of all available environmental observations, and machine learning techniques, DestinE will develop high-accuracy digital twins, or replicas, of the Earth.  DestinE will thus allow users to better explore the evolution of the Earth system, and to test a range of scenarios and potential mitigation strategies.
Under the European Commission's leadership, and in coordination with the Member States, scientific communities and other stakeholders, ECMWF, ESA and EUMETSAT are the three entrusted entities tasked with delivering the first phase of the DestinE by 2024.
ECMWF is responsible for building the ‘digital twin engine’ software and data infrastructure and for using it to deliver the first two high-priority digital twins, while European Space Agency (ESA) provides the platform through which users will access the service, and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) develops the data repository.
This talk will give a high-level introduction to the initiative, and it will particularly focus on one of the first two priority digital twins that ECMWF is developing: The Digital Twin on Weather-Induced and Geophysical Extremes (Extremes DT). This Digital Twin will provide capabilities and services for the assessment and prediction of environmental extremes from global to local scale, on a time scale of a few days ahead.
In this talk, we will particularly focus on the global, continuous component of the Extremes DT, that we are developing at ECMWF using our Integrated Forecasting System. We will showcase results from simulations at 4.5km and 2.8km resolution, to illustrate the benefits of the resolution increase for the representation of extreme events such as tropical cyclones, medicanes or intense precipitation events in mountainous regions. We will also discuss the lessons learned regarding aspects of the forecasting system that need to be further improved to exploit the advantages of the resolution increase for better representing extreme events.
System for Identification of Maize Ideotypes, optimal sowing dates and nitrogen fertilization under climate change - PREPCLIM
Authors: Caian Mihaela , Amihăesei Vlad
Published: July 2023

According to the IPCC reports climate change has begun to be evident and the prospects appear more worrying today than a few decades ago. Although progress is being made in studying the impacts of climate change on crops and agricultural production, these are rarely directly applicable to provide future-validated solutions due to the extremely high complexity of factors that intervene at the local scale of the crop through atmosphere/soil/process interaction phenological/ecosystems, etc.Providing an agro-ideotype requires the use of coupled climate-phenological modelling, at very high resolutions, capable of representing the processes involved at a very fine scale and extensive sensitivity simulations, performed under various projected climatic conditions and for a large number of combinations of the key phenological parameters (e.g. fertilization, sowing date, cultivar-dependent coefficients).We present the implementation and validation of a new integrated climate / phenology / decision support (CPD) modeling system (based on CORDEX models / DSSAT model), a TLR4 system, developed under the frame of PREPCLIM project, and the results of system simulations carried out to identify the ideotypes for miaze in the near future climate (2050) for SE Europe/ Romania. Ideotyping with CPD system was carried out for an ensemble of genotyping codes (a genotyping code involed ~ 2000 simulations), for each testing alternate 12 treatments (4 planting dates and 3 fertilisation levels). The criteria for selecting optimal genotypes was according to user requirements: maximum production, stable production, minimizing the amount of leached nitrogen below the maximum level of the root front (reducing the risk of water table pollution), etc. The CPD system was validated for the southern area of Romania (Călăraşi) for the actual climate conditions. Projected changes in ideotype were simulated for two scenarios: RCP45 and RCP85 against historical simulations using an ensemble of three CORDEX models. The results for this ensemble indicate, for the control genotype, a mean decrease in production in both scenarios for all sowing dates and fertilisation levels tested, changes that were analised în relation to several factors: - a decrease (and time-shift) in the accumulated rainfall in the growing period, - a systematic earlier  flowering date and date of reaching physiological maturity, the two leading a shortening of the crop season; - a decrease in fertilization efficiency mainly for later  sowing dates and especially in RCP8.5. An open-source, operațional, user-interactive interface for this Agro-Climatic Service, în the support of agro-adaptation to climate change is operative under EERIS platform (eerir.eu/index.php)
Recent European heat waves under three dimensional insight
Authors: Lhotka Ondřej , Plavcová Eva , Kyselý Jan
Published: July 2023

In recent summers, Europe was struck by numerous heat extremes that have almost completely redrawn the map of the most severe heat waves recorded across the continent (Lhotka and Kyselý 2022). For example, daily maximum temperature over 40°C was measured for the first time ever in the United Kingdom in 2022, surpassing the previous all-time high (recorded only three years earlier) by 1.5°C. During the past decade, heat waves were extensively studied due to their growing negative consequences on environment and society. Those studies mostly focused on hazardous near surface temperatures and their impacts, however, heat waves depend on processes taking place through the entire troposphere. In this study, we assess heat waves not only in terms of near surface temperatures but also temperatures at the 850 and 500 hPa levels from the ERA5 reanalysis. Heat waves are defined based on spatially conditioned exceedance of the 90% quantile of summer daily temperature distribution with a three-day minimum persistence criterion (at any pressure level). Their characteristics (magnitude, length, intensity, and spatial extent) are analysed for several European regions from 1989 to 2022 (with backward extensions planned). Preliminary results suggest that a large number of heat waves is detectable in atmospheric column spanning from the Earths’ surface approximately to the 300 hPa level. Other events, by contrast, are limited to lower or upper troposphere only, suggesting different driving mechanisms. Interannual variability and trends of heat wave characteristics in three dimensional space are also investigated.
References:
Lhotka, O., & Kyselý, J. (2022). The 2021 European heat wave in the context of past major heat waves. Earth and Space Science, 9. https://doi.org/10.1029/2022EA002567
Again another once-in-a-lifetime flood? - Exploring ways to communicate climate extremes
Authors: Böhnisch Andrea , Mittermeier Magdalena , Gregow Hilppa , Vajda Andrea , Mäkelä Antti , Korhonen Natalia , Riuttanen Laura , Ludwig Ralf
Published: July 2023

(Hydro-)meteorological extreme events account for a large portion of immediate exposure to and long-term impact by climate change for humans, ecosystems and infrastructure worldwide. These extremes, especially high-impact events, are often communicated by means of return periods, e.g., a 1-in-100 years flood, a 1-in-50 years drought. Frequency increases are already observed for a range of meteorological extremes, in parts also at temporal scales of merely a few decades (i.e., less than a human lifetime). Distributional shifts of atmospheric variables, e.g., temperature or precipitation, lead to further frequency increases of (current) extremes and the emergence of yet unseen, sometimes compound and cascading events. Therefore, one could think that the (decreasing) rareness of extreme events forms a good basis for illustrating the impacts of climate change among the broad public.
However, the common reaction is similar to the headline introduction: Again another once-in-a-lifetime flood? But we just had one last year … In other cases, the new regularity of extreme events often seems to cause habituation or fatalism rather than concern.
Apparently, there is a discrepancy between the scientific understanding of extremes on the one side and the public perception and personal experience on the other side. In this contribution, we try to illustrate this discrepancy and explore ways to approximate the different perceptions.
We start by showing how prominently return periods are used explicitly and implicitly in grasping extremes (both in science and everyday-talking). A clear scientific definition will follow and hint to potential sources of misunderstanding. We next present examples where return periods are used for communicating (hydro-)meteorological hazards to the general public: 1. teaching the meaning and understanding of meteorological data with a focus on extremes with the “Living with changing climate”-course of the Finnish Climate University initiative (https://climateuniversity.fi/portfolio-items/living_with_changing_climate/), which is targeting people from outside academia as well, and 2. results from the Bavarian-Québec ClimEx project (https://climex-project.org) formatted as a hydrometeorological atlas. Further, we discuss ideas of tailoring return periods to peoples’ life experience e.g. by referring to literature and using 80-years as the averaged life expectation.
We conclude by summarizing where we think that these examples succeed or struggle in clarifying the meaning and implications of extremes and provide an outlook on further ideas and narratives to bridge the gap between science and society.