bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance and Mortality of Gambusia affinis to Acute Ammonia and Nitrite Exposure at Various Salinities
Authors: Chithambaran Sambhu , Abdullah Emad Ali , Al Deen Samy
Published: June 2022

Tolerance and mortality of mosquito fish, Gambusia affinis to acute ammonia and nitrite exposure at various salinities were studied in fibreglass tanks (500L) for a period of 4 months at KAU Fish Farm, Faculty of Marine Sciences, Jeddah. Salinity tolerance was tested in 0 (Control) 10, 20, 30 and 40 ppt. After tolerance study, 60 fish from each salinity was taken for ammonia and nitrite exposure study. Ammonia toxicity was tested in 0, 0.5, 1, 2, 3 and 4ppm; while nitrite was tested at 8, 10, 12, 14 and 16 ppm. Survival decreased when salinity increased from 0 to 40 ppt and a significant relationship (R2=0.959) was found between increase in salinity and survival. Mortality rate was found to be increased when ammonia and salinity level increased and the highest mortality was observed in the highest dosage of ammonia (4ppm) and salinity (40ppt). Similarly, increased mortality was observed in higher levels of nitrite and salinity. Results show that Gambusia affinis can tolerate salinity up to 40 ppt, ammonia at 1ppm and nitrite toxicity at <8ppm.
Effectiveness of a Wool Based Packaging System on the Abundance of Surface Spoilage Microorganisms on Meat Products
Authors: Lahmer Rabya A. , Morris Angela , Curling Simon F. , Ormondroyd Graham A. , Jones Davey L. , Williams Prysor A.
Published: June 2022

Sheep wool can be used as an eco–friendly type of packaging that, due to its complex physical and chemical composition, can also help control humidity and reduce condensation. Given these properties, the potential of wool to be used as packaging liners for the transport of food products is of interest. The present study assessed the microbiological quality of meat packaged and stored at room temperature for 40 h in conventional EPS (expanded polystyrene) boxes and cardboard boxes lined with wool using standard, approved culturing techniques. The findings suggest that the wool may have potential market value as packaging liners for transporting meat, and possibly other food products. Further research is needed to allow better characterization to real-world conditions, and understanding of how wool used as a packaging liner could help maintain food quality on a larger scale.
Dubbelrecensie van Ad van Liempts 'Gemmeker' en Rudolf Dekkers 'Plagiaat en nivellering'
Authors: Wouters Nico
Published: June 2022

Deze bijdrage is onderdeel van het discussiedossier 'Omgang met de Tweede Wereldoorlog: integriteit en nivellering'.
De historicus als implicated subject
Authors: Henkes Barbara
Published: June 2022

In mijn bijdrage aan dit discussiedossier plaats ik de kritiek op Van Liempts benadering van het oorlogsverleden – in zowel zijn proefschrift (2019) als in de serie De Oorlog (2010) – in een breder debat over de Nederlandse geschiedschrijving van de Tweede Wereldoorlog en de Shoah. Ik volg uiteenlopende pogingen van Van Liempt en anderen om tot een ‘neutrale’ geschiedschrijving te komen, waarbij morele overwegingen van ‘goed’ en ‘fout’ doelbewust terzijde geschoven worden. Ik beargumenteer dat dit streven naar een positie die boven de partijen verheven zou zijn, ontkent dat historici zelf geïmpliceerd zijn in hun geschiedschrijving.  Geïnspireerd door het werk van Michael Rothberg laat ik zien dat de positie van de bystander – evengoed als die van de dader, slachtoffer of verzetsstrijder – medebepalend is voor de dynamiek van de historische gebeurtenissen. Hetzelfde geldt voor de implicatedness van historici in hun eigen geschiedverhaal zoals zich dat in het heden ontvouwt.
Hierarchical deconvolution for incoherent scatter radar data
Authors: Ross Snizhana , Arjas Arttu , Virtanen Ilkka I. , Sillanpää Mikko J. , Roininen Lassi , Hauptmann Andreas
Published: June 2022

Abstract. We propose a novel method for deconvolving incoherent scatter radar data to recover accurate reconstructions of backscattered powers. The problem is modelled as a hierarchical noise-perturbed deconvolution problem, where the lower hierarchy consists of an adaptive length-scale function that allows for a non-stationary prior and as such enables adaptive recovery of smooth and narrow layers in the profiles. The estimation is done in a Bayesian statistical inversion framework as a two-step procedure, where hyperparameters are first estimated by optimisation and followed by an analytical closed-form solution of the deconvolved signal.
The proposed optimisation-based method is compared to a fully probabilistic approach using Markov chain Monte Carlo techniques enabling additional uncertainty quantification. In this paper we examine the potential of the hierarchical deconvolution approach using two different prior models for the length-scale function.
We apply the developed methodology to compute the backscattered powers of measured polar mesospheric winter echoes, as well as summer echoes, from the EISCAT VHF radar in Tromsø, Norway. Computational accuracy and performance are tested using a simulated signal corresponding to a typical background ionosphere and a sporadic E layer with known ground truth. The results suggest that the proposed hierarchical deconvolution approach can recover accurate and clean reconstructions of profiles, and the potential to be successfully applied to similar problems.
A process-based understanding of Greenland Blocking regime life cycle dynamics in ERA-5 reanalysis from a potential vorticity perspective 
Authors: Hauser Seraphine , Knippertz Peter , Quinting Julian F. , Riemer Michael , Teubler Franziska , Grams Christian M.
Published: June 2022

Atmospheric blocking describes a flow configuration that is associated with the meridional reversal of the large-scale atmospheric circulation in the midlatitudes. Due to the blocking of the mean westerly flow and the disruption of the eastward propagation of embedded synoptic-scale weather systems, such situations can lead to many kinds of extreme weather - within the block itself but also in adjacent regions. One blocking type of particular interest is the Greenland Blocking as it is more long-lived than blocking over other regions and strongly related to the negative phase of the North Atlantic Oscillation. Greenland Blocking has a strong surface impact, as the associated temperature anomalies can lead to ice sheet melting. It is therefore crucial to understand the underlying processes and dynamics of blocking in this region.

Here we look at Greenland Blocking from a year-round weather regime perspective based on ERA-5 reanalysis data from 1979-2021 focusing on the dynamical life cycle of the block. A diagnostic, quasi-Lagrangian potential vorticity (PV) framework has been developed and is applied to all Greenland Blocking weather regime life cycles. The framework allows the tracking of negative, upper-tropospheric PV anomalies in the Northern Hemisphere and assigns them to regime life cycles. With piecewise PV inversion, we partition the PV tendency equation into different contributions – separated into advective and diabatic PV tendencies – to disentangle different physical and dynamical processes that affect the amplitude evolution of the negative PV anomalies. This complements the quasi-Lagrangian framework and enables us here to distinguish the roles of dry and moist dynamics in the life cycle of the Greenland blocking regime.

Our results show that most negative, upper-tropospheric PV anomalies that are associated with Greenland Blocking regime life cycles are not generated locally over Greenland. We present different pathways by which the PV anomalies reach the area of the incipient block and analyze their seasonal dependence. A detailed investigation of the individual pathways and their associated negative PV anomalies reveals that the amplitude evolution of the PV anomalies is characterized by different proportions of dry and moist processes. Seasonal differences between the occurrence of these pathways emphasize the complexity of the underlying processes.
Energy meteorology and economics - Transdisciplinary success from the Hans-Ertel-Centre for Weather Research
Authors: Fiedler Stephanie , Czock Berit , Frank Christopher , Ho Linh , Kenny Darragh , Luiz Eduardo Weide , Keller Jan , Crewell Susanne , Bettzüge Marc Oliver
Published: June 2022

The research area Climate Monitoring and Diagnostics of the Hans-Ertel-Centre for Weather Research advances the fundamental science basis for energy meteorology and translates the physical knowledge into stakeholder-relevant information for a climate neutral energy system in Europe. We show recent successes building on a kilometre-scale reanalysis dataset for Europe that was developed by the HErZ research area at the Universities of Cologne and Bonn, and produced by the German Weather Service. Paired with contemporary models for renewable power production, we carry out transdisciplinary research across meteorology and economics to answer urgent questions for the energy transition from currently primarily fossil fuels to a future energy system that relies more on renewables energy sources. Our research follows a seamless approach ranging from the assessment of weather and climate processes for wind and photovoltaic power production via economic system modelling and price estimates to communicating our research results to stakeholders in industry and politics, engaging in public outreach on national level, and teaching the next generation about our HErZ research. Scientific results from our works highlight (1) balancing potentials of natural variability and extremes in the production of wind and photovoltaic power across Europe, (2) distinct synoptic-scale weather patterns for dark doldrums with a possibility of compensating power shortfalls with sufficient storage capacities for a secure power supply, (3) nocturnal low-level jets having both beneficial and adverse impacts on wind power production, and (4) different biases in gridded irradiance datasets for estimating photovoltaic power production in comparison to on-site measurements. The research area closely collaborates with the Institute of Energy Economics at the University of Cologne (EWI). This cooperation informs the research agenda from an energy system perspective and facilitates the rapid transfer of research results into policy-relevant work, such as e.g. a contribution to EWI's report for the "dena Study Integrated Energy Transition" (dena, 2021). The dena Study, commissioned by the German Energy Agency (dena), has been widely received in the German policy debate, and it raised substantial public awareness e.g. by way of press releases and interviews for major newspapers. Future directions of the fruitful collaboration will involve blending climate change scenarios into the work of the research team for knowing possible extreme weather impacts on a redesigned energy system before they occur.
The need for global hydro-climatological indicators
Authors: Benestad Rasmus E. , Lussana Cristian , Lutz Julia , Dobler Andreas , Landgren Oskar A. , Haugen Jan Erik , Mezghani Abdelkader , Casati Barbara , Parding Kajsa M.
Published: June 2022

Global warming is expected to alter the global hydrological cycle in addition to higher temperatures, higher global sea levels and melting ice. We present an analysis of how rainfall patterns have changed over the period 1950-2020 based on the ERA5 reanalysis, involving both aggregation and 2D Haar wavelet analysis. Our results suggest that there have been pronounced changes, such as increased activity in rain events with a size of less than 400 km. Such changes call for the need for global hydro-climate indicators that provide a summary of the state of the global hydrological cycle. We show that the typical total mass of water falling on Earth’s surface each day has gradually increased over the period, and the daily fraction of the global area on which it falls has diminished. Hence, the mean rainfall intensity has also increased. These findings imply two explanations for observed trends toward more extreme rainfall: (1) a more moist atmosphere and (2) the rainfall has increasingly become more concentrated in both time and space. One hypothesis is that these changes in rainfall patterns may be connected with changed conditions for convection in the atmosphere. We found that the energies in some of the wavelet components closely track the global mean temperature, which also may suggest a possibility to downscale statistics for rainfall patterns based on expected global warming. A practical consequence of these findings is an explanation for both more flooding in some places but also more drought in others. They also call for the need to include global hydro-climatological indicators in the widely used set consisting of the global mean temperature, global sea-level, CO2 concentrations and sea-ice extent.
Nonadiabatic and nonquasigeostrophic sources of upper tropospheric Rossby wave activity
Authors: Lee Hung-I , Nakamura Noboru
Published: June 2022

The budget of local (Rossby) wave activity in the quasigeostrophic (QG) limit is largely governed by the convergence of wave activity fluxes: the zonal advective flux by geostrophic flow and the Eliassen-Palm (EP) flux, i.e. radiation stress associated with baroclinic wave packets traveling through an inhomogeneous jet stream. The residual of the budget presumably accounts for nonadiabatic and non-QG sources and sinks of wave activity.  Here, we analyze ERA5 data to evaluate non-QG wave sources in the upper troposphere associated with local diabatic heating and advection of potential vorticity by ageostrophic (divergent) flow driven by remote heat sources.  (The diabatic heating is estimated from the material tendency of potential temperature.)

 

Climatological mean distribution of the upper tropospheric wave activity sources in the Northern Hemisphere reveal a few hot spots:

Local diabatic sources:  In winter (DJF), large positive values are spotted over the northeast Asia to the Sea of Japan.  Secondary maxima are found in the subtropics of the eastern Pacific and the Atlantic.  In summer (JJA), large positive values are found in the subtropics from the Indian Ocean to the western Pacific and in the subtropics of western Atlantic and North America.  

Non-QG sources (ageostrophic advection of PV): In winter (DJF), large positive (negative) values are located in the subtropics (midlatitudes) of the eastern Pacific. Somewhat surprisingly, significant secondary maxima (positive values) appear in the midlatitudes of the eastern Pacific and along the Atlantic storm track.  In summer (JJA), large positive (negative) values are centered on the subtropics (midlatitude) of the Eurasian continent but they extend over a broader range of longitudes.

Previously it has been recognized that the climatological-mean wave activity is enhanced on the eastern side of the column water vapor maximum (quasi-stationary atmospheric river or QSAR) at 30°N during the cold season but on both sides during summer (Lee and Mitchell 2021).  The present study suggests that the eastward enhancement of wave activity is the result of production of wave activity by the local diabatic sources at QSAR and the subsequent downstream advection by the jet stream.  The enhancement of wave activity west of QSAR during summer on the other hand arises from the combination of diabatic heating and ageostrophic advection of potential vorticity, both enhanced by the Asian summer monsoon in the subtropics of the Eurasian continent.  
Evaluation of Columnar Database Tables for Producing Climate Aggregates on Demand
Authors: Casey Dáire , Lally Conor , Elliott Dára
Published: June 2022

Evaluation of Columnar Database Tables for Producing Climate Aggregates on Demand

Dáire Casey, Conor Lally, Dára Elliot

Met Éireann, Maynooth University

 

Modern automated observing networks generally produce observations at a time resolution of one minute or less. For climatological and other purposes, longer time resolutions are required such as ten minute, hourly, daily, and monthly. Using traditional relational databases, this necessitates the creation of derived values, i.e. aggregates computed from a set of individual observations such as accumulation, averages and extremes.

With the potential for quality control processes to subsequently modify observation values, ensuring consistency between the different time granularities is exceptionally difficult. This can lead to undesirable variations between related original values, derived, and aggregates.

New columnar databases and related analytical query engines provide massive performance enhancements for certain data-types. This introduces the possibility of determining climatological derived values and aggregates on demand as opposed to pre-calculating them. This eliminates the potential for inconsistency between time granularities. But considering the huge size of many observations and climate datasets, is the performance of columnar databases good enough to meet the operational requirements of a National Meteorological Organisation? This will be determined by querying a columnar database and an equivalent row-oriented database with a set of varied queries and comparing the speed at which results are returned. This research will have important implications for observations and climate data storage systems used by National Meteorological Organisations such as Ireland’s Met Éireann. Moreover, this approach may prove advantageous to those wishing to use data science applications on climate and weather data sets on the cloud.
Measurement of a Vortex with Double-Helical Structure in a Laboratory Tornado Simulator by Sonic Anemometer-Thermometer
Authors: Itano Toshihisa , Okuyama Kento
Published: June 2022

Natural and artificial tornadoes take a special form called “multiple vortex structure” where two or more secondary vortices revolve around the eye of their parent vortex. The structure is seen when the Swirl ratio, one of the three dimensionless number governing the system, is larger than 0.3 – 0.4. In the meanwhile, around the lower limit of the Swirl ratio to give the multiple vortex structure, two secondary vortices intertwined with each other emerge to form double helical configuration similar to DNA. We reproduced such a vortex in our laboratory tornado simulator at National Defense Academy (NDA), Japan, and attempt to reveal its structure through a velocity measurement.

For this purpose, we adopt a Sonic anemometer-thermometer (SAT) developed for indoor use (Sonic/Kaijo WA-790) instead of conventional anemometers for laboratory experiments, i.e. Pitot tube, Hot-wire anemometer, Laser Doppler Velocimetry (LDV), etc. This is because wind field in the interior of the vortex is unsettled especially when two or more secondary vortices are embedded within it, and then it is geometrically impossible to measure the wind from the rear side of the probe by Pitot tube, even omnidirectional one, and a Hot-wire anemometer, even two- or three-dimensional one, respectively. Similarly, it is difficult to provide optical axes for LDV in a tornado simulator with complex configuration. In this respect, the indoor SAT is desirable since it can measure three components of wind velocity without any restrictions on wind direction. The probe of WA-790 consists of three set of transduces disposed 3 cm apart with each other. Thus, although the probe is considerably larger than that for Pitot tube or Hot-wire anemometer, it is sufficiently small compared with the size of the vortex spawned in our tornado simulator at NDA, which is about 20 cm in diameter.

We carried out velocity measurement at 87 points on the vertical cross section of 40 cm high and 30 cm wide set in the vortex simulator, which has concentric cylindrical structure with inner diameter of 130 cm and outer diameter of 190 cm, respectively and the height of 95 cm. Each run of velocity measurement is set to be 4 min long and three component of wind speed is obtained with 10 Hz. While the parent vortex is revealed on the average wind fields, the structure of the secondary vortices and their momentum transport are examined statistically on the variance and covariance fields, respectively. In addition, to show their time variations, the spectra and co-spectra of wind speed are also investigated.
The sub-seasonal variability of the South Asian High and its relationship with East Asian summer monsoon seasonal precipitation
Authors: Lu Mong-Ming , Chen Po-Chia
Published: June 2022

The South Asian High (SAH) is the most pronounced boreal summer upper tropospheric dynamic system over Asia. The dominant modes of the SAH sub-seasonal variability are captured by the EOFs of 200-hPa daily geopotential height over 40°-120°E, 10°-40°N from June to August during 1979-2021. EOF1 shows a single center pattern with the maximum variance over the Iranian Plateau. The corresponding principal component (PC) shows an increasing tendency of the SAH in particular after the year 2010. EOF2 shows an east-west dipole pattern. Its PC has a spectral peak period of around 20 days. The composite analysis based on the negative (west mode) and positive (east mode) phases of the EOF2 reveals that the wave trains associated with the west and east modes can be traced back to the northeastern Atlantic and Ural Mountains, respectively, about two weeks before the wave reached the SAH region. The Ural ridge for the east mode excited two branches of waves, one propagated equatorward into central Asia and another propagated along 60°N into Central Siberian Plateau. The two wave trains later formed a quadrupole pattern over and to the north of the SAH. The west (east) mode composite precipitation shows wet (dry) over the Indian subcontinent and dry (wet) over the Bay of Bengal over South Asia, while over East Asia it shows dry (wet) over North China and wet (dry) over South China. In addition, the east mode has an unique tripolar pattern with dry over East China and wet over Japan and the Philippines. The sub-seasonal relationship between high-latitude Rossby waves and the SAH can influence the monsoon precipitation that is tightly locked with the annual cycle. The linkages with the tropical water vapor transport, MJO, BSISO and the extremely wet/dry seasons will be discussed.
Disentangling diabatic and adiabatic drivers during the life cycle of a jet streak from a Lagrangian PV-gradient perspective
Authors: Bukenberger Mona , Schemm Sebastian , Rüdisühli Stefan
Published: June 2022

 

 The jet stream is a circumpolar global band of high wind speeds in the upper troposphere. Meridional jet meanders lead to high-impact weather events and synchronize them over thousands of kilometres. Locally, the jet stream can be typified by concentrations of extreme wind speeds in so-called jet streaks, whose formation mechanisms are largely unknown. 

The mean position and intensity of the jet is to first order determined by the meridional temperature gradient and its variation with altitude, following the thermal wind relationship. On synoptic timescales, however, jet streaks arise from a complex interaction between adiabatic and diabatic processes with their relative importance difficult to disentangle. To obtain a mechanistic understanding of the formation of jet streaks, however, a proper understanding of the relative role of adiabatic and diabatic processes is crucial. 

Here, a novel Lagrangian PV-gradient framework is introduced that allows to quantify the role of adiabatic and diabatic processes during the life cycle of jet streaks. First, the theoretical foundation of the widely used link between horizontal isentropic PV-gradients and the jet is revisited. It is shown that the zone of highest PV gradient must be located always on the stratospheric side of the jet. Further, the jet evolves hand in hand with the natural logarithm of the PV gradient for wave lengths exceeding approximately 50 km on Earth-like planets. 

Next, using a case study, the novel diagnostic is discussed in the context of Lagrangian PV-gradient tendencies computed fully online in a convection resolving 1-km COSMO simulation. Individual contributions are separated into adiabatic processes such as deformation, direct diabatic contributions such as condensation and indirect diabatic contributions from deformation acting along non-conserved PV. 

The presented case study analyses two jet streaks of different origin and intensity during the NAWDEX period. The relative roles of diabatic and adiabatic processes in the strengthening and weakening of the PV gradient varies widely between the two and between different phases of their life cycles. Cloud processes play an important role for the jet streak at time of its main intensification phase while during most of the life cycle, adiabatic deformation dominates the PV gradient evolution. 
Predictability of midlatitude Rossby wave packets and their underlying dynamics
Authors: Prestel-Kupferer Isabelle , Schmidt Sören , Riemer Michael , Teubler Franziska
Published: June 2022

Rossby Wave Packets (RWPs) are linked to extreme weather events and exert a strong influence on the predictability of weather systems in the midlatitudes. Considering the whole wave packet, in the sense of the packet envelope, RWPs can be viewed as entities that describe variability of the atmosphere beyond the synoptic scale.

We here examine the predictability of RWPs as such entities. As a skill metric we used the so-called Displacement and Amplitude Score (DAS) applied to the envelope field of the midlatitude flow. The DAS is based on a field deforming method and, as one of its major advantages, avoids the “double-penalty” verification problem without the need to identify single RWP-objects. Object-based methods tend to be highly sensitive to the choice of thresholds used to identify the objects and conceptual issues arise when assigning forecast to analysis objects. We assess RWP predictability using NOAA GEFSV12 ensemble reforecasts for RWPs that have been previously tracked in ERA5 data, due to the higher available temporal resolution. The ERA5 dataset was also used to quantify individual dynamical contributions to the amplitude evolution of single RWPs by partitioning the PV-tendency equation.

A prominent result is that RWP predictability depends on the stage of the RWP lifecycle: The propagation stage exhibits higher predictability than the decay or genesis stage. A small seasonal dependence is found, with summer being the least predicable season. No significant dependence is found on size and amplitude of RWPs or their geographical location. The presentation will further discuss differences in predictability that arise due to differences in the dynamical proccesses that contribute to the evolution of RWPs.
On the water balance representation in urban land surface models
Authors: Jongen Harro , Lipson Mathew , Steeneveld Gert-Jan , Teuling Ryan
Published: June 2022

Urban Land Surface Models (ULSM) are developed to simulate the urban climate and vary in their complexity. The need for this complexity was assessed by two successive systematic intercomparison projects. Both projects focused on the energy balance and found the latent heat flux to be the most challenging flux to model. However, these projects did not address the closure of the water balance, although the energy balance is directly linked to the water balance. This study aims to assess the representation and dynamics of the water balance in 14 ULSMs from the Urban-PLUMBER project each ran for 20 sites. The water balance could not be evaluated by straightforwardly comparing the model results against measurements since most water balance fluxes are not measured. Therefore, the water storage dynamics were derived from the modelled water balance fluxes. We examined the inter-model variation in both the storage dynamics and the separate fluxes and developed seven indicators of a well-captured water balance. The variation in both the fluxes and the storage dynamics is in the same order of magnitude as the size of the fluxes themselves. The indicators show that no ULSM in this study can consistently reproduce a physically realistic water balance regardless of the model’s complexity. As the water balance is linked to the energy balance, the poor water balance representation may explain the poor performance for the latent heat flux. The linked balances illustrate model evaluations and comparisons should extend beyond the target variables of the model to all processes that directly influence these variables.
Predictability of Sub-seasonal Rainfall Associated with Large-scale Circulations
Authors: Luong Thang M , Dasari Hari P , Chang Hsin-I , Risanto C Bayu , Attada Raju , Castro Christopher L , Hoteit Ibrahim
Published: June 2022

Despite being one of the driest places in the world, the Kingdom of Saudi Arabia (KSA) occasionally experiences extreme precipitation events associated with organized convections that might lead to flooding. Rainfall forecasts at lead times on the sub-seasonal to seasonal (S2S) timescale can potentially assist disaster risk mitigation, and water resource management. Here, model skills of predicting precipitation at sub-seasonal scale (from 2 to 4 weeks ahead) are benchmarked over the Arabian Peninsula (AP). We utilized the Weather Research and Forecasting Model (WRF) at convective-permitting resolution (4 km) to dynamically downscale ensemble of 11 members of the European Centre of Medium-range Weather Forecasts (ECMWF) S2S reforecast product over a 20-year period (1998-2018). Representation of precipitation is assessed with a regional reanalysis over the AP and in-situ rain gauge measurements.

Precipitation mostly occurs over the AP during cooler months (November to April). Mesoscale convective systems (MCSs) are important factors in producing rainfall over the region during this period when extratropical systems are dominant. The majority of rainfall events in November to February are associated with extratropical forcing, while March and April rainfalls are associated with tropical-extratropical interactions.

Our results indicate that the WRF convective-permitting model adequately describes the precipitation patterns over the AP up to 4-week forecast-range and statistically improves the forecast skill with regard to its driving ECMWF fields over the studied 20-year period. Large-scale circulation signatures are reproduced in the model better in the spring wide-spread rainfall events for both WRF and ECMWF. WRF adds more values in simulating winter mesoscale convective systems.
Classification of extreme temperature events in the presence of seasonality and climate change 
Authors: Gubler Stefanie , Fukutome Sophie , Scherrer Simon C.
Published: June 2022

The knowledge on air temperature and its statistical characteristics is of great interest for a variety of applications. With the increased occurrence of hot spells in recent years, there is a growing interest in determining the recurrence probabilities of extreme temperature events. However, large temperature anomalies are not only important during summer, but also in other seasons with impacts for instance on health, agriculture, or hydrology. 

In this work, we present a method for deriving reliable estimates of the frequency of extreme temperature events as they occur throughout the year. Estimating the recurrence probabilities of extreme temperature anomalies is challenged by non-stationarities from long-term climate trends and strong seasonality. To tackle these challenges, we developed a statistical model for daily air temperatures that accounts for climate change and seasonality. The model assumes that observed daily temperatures at stations are a superposition of a non-linear trend and residuals from the Skewed Generalized Error Distribution (SGED) (Theodossiou, 2015), with parameters varying throughout the year as second-order harmonic functions. By applying the model, daily air temperatures are transformed into standardized anomalies that are comparable across and within years. These anomalies are then classified empirically to determine recurrence probabilities of large positive and negative temperature anomalies.

We introduce the temperature model, the estimated model parameters as well as the classification of extreme temperature anomalies. Further, we illustrate the influence of the chosen approach on the recurrence probabilities at the example of several events taking place in different years and / or in different seasons. A particular focus is put on the influence of climate change on return periods. The whole set-up was applied to air temperature observations in Switzerland, but has potential to work also in other regions.

References

Theodossiou, P. (2015): Skewed Generalized Error Distribution of Financial Assets and Option Pricing, Multinational Finance Journal, 19, 223–266, DOI: 10.17578/19-4-1.
Urban climate: Verfication of urban heat island mitigation strategies in the Swiss city Basel
Authors: Schlögl Sebastian , Smalla Tjark , Gutbrod Karl
Published: June 2022

Cities worldwide will be affected by anthropogenic climate change and additionally cope with additional heat due to greater heat storage capacity of artificial surfaces, less ventilation, and a higher risk of extreme floods due to sealed surfaces. Urban heat island mitigation strategies (such as rooftop greening, increasing surface albedo of the city and irrigation of green surfaces, which leads to significant evaporative cooling) are well known, but the magnitude in air temperature reduction is still not fully understood and significantly differs between cities.

A small area (“Triangel area”) was desealed and planted with 18 young trees at a 1 ha area in the center of the Swiss City Basel in March 2021. This urban heat island mitigation strategy was validated with a high dense low-cost IoT measurement network, which was installed in Basel in 2020 to detect urban heat islands. To validate the mitigation strategy properly, 3 air temperature measurements were installed in the Triangel area in 2020 and compared with more than 20 air temperature measurements in the reference area outside the mitigated area.

The measurements showed that the Triangel area is in general around 0.2 K cooler than the reference area. Furthermore, the differences in air temperatures between Triangel and reference area were calculated before and after the mitigation action to test the effectiveness of the method. An air temperature reduction of the Triangel area of 0.4 K after the mitigation action (in comparison with the reference area) was observed by the measurements.

The results from the measurement campaign were compared with model results using the surface energy budget model SUEWS. The SUEWS model results confirm an air temperature decrease of 0.4 K for the chosen urban heat island mitigation strategy and suggest other mitigation strategies (such as rooftop greening, watering and more). This approach allows to estimate the best possible mitigation strategy for the Triangel area with the largest reduction of surface and air temperatures. In summary, the approach helps city councils taking the right decision by choosing the optimal cost-value ratio in urban heat island mitigation strategies and prevents costly (and non-climate effective) strategies.
National hail climatology of Croatia
Authors: Blašković Lucija , Jelić Damjan , Malečić Barbara , Omazić Branimir , Telišman Prtenjak Maja
Published: June 2022

National hail climatology of Croatia

 

Lucija Blašković, Damjan Jelić, Barbara Malečić, Branimir Omazić, Maja Telišman Prtenjak (1)

 

(1) University of Zagreb, Faculty of Science, Department of Geophysics, Zagreb, Croatia

 

The step every country should take towards a better understanding of hail is national climatology. It is crucial to explore the temporal and spatial characteristics of this small-scale phenomenon in hope that it will contribute to better defense and preparation for such extreme weather. Even though Croatia is a small country, it has a relatively inhomogeneous climate due to its proximity to the Adriatic sea, a mountain range that in a way separates Croatia, etc. This research will analyze the diversity of the Croatian climate and its impact on the occurrence of hail. The results are based on hail data from 186 stations. This digitized data vary from station to station, so different time periods were observed. The results showed significant interannual and spatial variability, due to which it was necessary to divide into subdomains based on the season in which hail predominates - on the entire coast, the highest hail activity is present in the colder part of the year while the continental part of Croatia shows increased summer hail activity. There is also a transitional area that records most hail in spring and fall. The trend analysis was made for two time periods: 1.) from 1964. to 2019., 2) from 1984. to 2019. and both periods have shown signs of a negative trend in a number of hail events. Daily patterns show a shift in the daily maximum from morning to afternoon hours as we approach the continent from the coast, and the highest frequencies are recorded in Šibenik and Zavižan of as much as 3.8 and 4.8 days with hail per year. Finally, instability indices were studied, which could explain the atmospheric conditions in which hail occurs.

 

 
Precipitation Nowcasting by Deep Physics-Constrained Neural Networks
Authors: Choma Matej , Bartel Jakub , Šimánek Petr
Published: June 2022

During last year's summer storm season, we have introduced a precipitation nowcasting neural network MWNet and deployed it to operational use. The network tackles the nowcasting problem as a sequence to sequence prediction of radar echo, emphasizing high resolution and accuracy. We have conducted two quantitative experiments comparing MWNet 60 min forecasts to other available precipitation nowcasting models, using the metrics CSI and MSE. Both evaluations, over the domain of Denmark for years 2018 - 2020 and over the Czech Republic for the summer storm season of 2021, concluded in favor of our approach. However, we aim to improve MWNet capabilities further by focusing on severe weather nowcasting, the physical soundness of the predictions, and lead times longer than 60 min. Building on the advances in deep learning and its use in spatio-temporal forecasting, MWNet is based on the idea of disentangling physical dynamics from the residual factors. In this contribution, we consider improvements to the physical part of the network, its incorporation into the whole model, and the loss function used during training. Mainly, we are exploring the effect of implementing non-linear partial differential equations into the physical part, with various levels of hand-engineering equation terms. We analyze the impact on the dynamics learned by each part of the network and prediction quality for each setting. MWNet v1.2, based on the proposed architecture, will be operationally used and evaluated by meteorologists in Meteopress during the summer of 2022. This work aims to contribute to bridging the gap between machine learning and physical modeling in weather forecasting, alongside improving precipitation prediction.
Solar resource mapping in Norway
Authors: Dobler Andreas , Berge Erik , Eastwood Steinar , Førland Jean Rabault , Hygen Hans Olav , Sætra Martin Lilleeng
Published: June 2022

Dramatically reduced costs, increased electrification and a growing resistance to onshore wind power, makes solar energy, and photovoltaics increasingly relevant in Norway. However, there is a lack of accurate knowledge on the available solar resource. Of key importance is solar irradiance, and the accuracy of this is paramount for the accuracy of energy production estimates. Global horizontal irradiation (GHI) for a location can be found in several different databases, but they are less reliable for high latitudes such as Norway. In our study of the solar resource in Norway we assess surface measurements, satellite data, re-analysis and weather prediction model data. Surface measurements are available for about 100 locations in Norway, but the quality of the data is often not well documented, and quality assurance is necessary. Due to the lack of coverage of geostationary satellite data over the Northernmost part of Norway polar orbiting satellites are preferred, but the passages of the polar satellites are temporally irregular. Model GHI data has regular temporal resolution and availability, but the accuracy is uncertain and needs further exploitation. In this work we present a quality assurance of surface GHI measurements including visual inspection tools, and a comparison of the quality assured surface measurements with satellite and model derived GHI. A discussion of the three data sets is given and a preliminary solar resource map for Norway is also presented.  Our study shows that locations with the highest annual GHI of ca. 1000-1100 kWh/m2 are encountered in high mountain areas with GHI peaking in late spring early simmer when the mountains still are covered with snow. Slightly lower GHI values of about 1000 kWh/m2 are found at southern coastal sites reaching the peak GHI in mid-summer. Lower values of typically 700-800 kWh/m2 are seen at the west coast and 600-700 kWh/m2 are in northern Norway. 
In situ observation of radiative fluxes from surface to lower stratosphere
Authors: Becker Ralf , Wacker Stefan , Doppler Lionel , Filipitsch Florian , Philipona Rolf
Published: June 2022

Balloon-based soundings have been carried out for more than 100 years and have since formed an important database and reference for characterizing the 3-dimensional structure of the atmosphere. In addition to the meteorological standard variables trace gases, aerosol and radiation profiles have recently also been recorded using radiosondes.

Since this is significantly more expensive equipment compared to a standard radiosonde, some more effort is required to enable safe soundings and transfer back home for each case. The repetition rates of the soundings are consequently much lower than those of the operational measurements.

The measurement conditions during the sounding differ significantly from the usual conditions for radiation measurements near the ground: temperatures down to -85°C at the tropopause level, rapid temperature changes of more than 50 K/h at an ascent rate of 5 m/s and possible impacts of liquid and iced cloud droplets on the observations need to be handled. This requires adjustments to the acquisition of measured values ​​and a careful selection of the launch time.

At Lindenberg Meteorological Observatory (52.21° north, 14.12° east) of the German Weather Service, a total of 68 all-season sounding flights have been carried out since April 2015 with modified radiosondes of the Meteolabor SRS-C34 and SRS-C50 type with added upward and downward solar and terrestrial radiation.

This presentation is discussing and interpreting the observational results of individual cloudless cases as well as soundings passing low, medium and high clouds. The downward fluxes are significantly modified below the tropopause. On the other hand, reflected radiation and terrestrial radiation are not only subject to local changes, even up to an altitude of 34 km, which can be quantified by including data on land use and cloud cover.

In addition, we will show the result of a case study where the radiative fluxes observed in and around clouds are used to validate corresponding numerical simulations performed with the ICON-ART model.
Ensemble dispersion improvement auto-tune (EDIT), a generic post processing step for Machine Learning regression results with quantified uncertainty
Authors: de Baar Jouke , de Valk Cees , van der Schrier Gerard
Published: June 2022

In various machine learning (ML) approaches, we are moving towards reliable quantification of uncertainty of results. More and more, it is becoming clear that without quantified uncertainties it is difficult to compare ML-based results or predictions. In addition, users of ML results are becoming more and more inclined to consider uncertainties in the decision-making process. Apart from providing results, it is becoming important to provide a quantified statement of accuracy – in fact, one might argue that a ML result without quantified uncertainty is actually an incomplete result. Therefore, an important generic question is: how do we ensure that the reported uncertainties are indeed reliable? 

Presently, we approach this question by developing and applying ensemble dispersion improvement auto-tune (EDIT) for spatial regression. Where cross-validation is often used to check the quality of an ensemble prediction a posteriori, for example by constructing rank histograms, in EDIT we use cross-validation to optimize the ensemble spread. This correction is made as a function of EDIT proxies, that is, covariates that might be important indicators of the magnitude of the correction we should make. In our case, we use a multi-objective optimization, which targets both the flatness of the regression rank histogram and the accurate dependency of the regression uncertainty on proxies. 

In this work, we consider the example of spatial regression of in situ observations of daily mean wind speed in Europe for the period 1980 – 2021 as part of the E-OBS data set. In such products, we provide maps of historical wind speed, and communicate the uncertainty in our results by providing an ensemble of maps. Important EDIT proxies for ensemble dispersion correction are the distance to the nearest station and complexity of terrain. Using EDIT, we see a significant improvement of the reliability of the ensemble dispersion. 
The Copernicus climate change service: current status and future perspectives.
Authors: Buontempo Carlo ,   C3S leadership team
Published: June 2022

At the end of July 2021, the Climate Change Service of Copernicus, signed a new contribution agreement with the European Commission which will support the service until the end of 2028. Over the course of the next 7 years ECMWF,  which has been entrusted with the responsibility of implementing the service, will continue to make climate data freely available to its many users in Europe and beyond  and will support the mainstreaming of climate service provision.

The current portfolio of the service ranges from historical observations to climate projections and includes both reanalyses and seasonal prediction products. The technical infrastructure underpinning the service, which is about to be modernised, also offers the possibility to efficiently process the data and transform it into insight usable by a variety of user communities.

The talk will present the current structure of the service highlighting some of its more innovative elements but also offering some critical reflections on those elements of the programme that have proven harder to tackle and will conclude by summarising the key evolution of C3S within this new phase. A particular emphasis will be given to the role C3S will play in enhancing further its support to its downstream users, including  national meteorological services, national or international agencies or private enterprises operating on climate related topics.