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Rapid population increase, industrialization and pollution are putting a strain on available and diminishing freshwater resources. Recent climate projections suggest a drop of up to 10 % in precipitation in most of Southern Africa by 2050. The main aim of this paper is to assess the impact of climate change on water resources in a semi-arid river basin in South Africa using two downscaling approaches: statistical downscaling (SDE) and dynamic downscaling (CORDEX) approaches. Both SDE and CORDEX data were derived from the GCM simulations of the Coupled Model Inter-comparison Project Phase-5 (CMIP5) and across two greenhouse gas emission scenarios known as Representative Concentration Pathways (RCP) 4.5 and 8.5 with a spatial resolution 25 km × 25 km for SDE and 50 km × 50 km for CORDEX. Four GCM models were used for both approaches. SWAT hydrological model was run using these data for a period of 2020 to 2050. Varied results were obtained depending on the type of climate model used, but generally, the trends were similar in most cases. For SDE approach, the multi-model average showed a possible decrease in precipitation (by 14 %), a decrease in water yield (by 15 %) and an increase in potential evapotranspiration (by 10 %). For CORDEX data, the multi-model average showed a possible decrease in precipitation (up to - 3 %), a decrease in water yield (up to - 13 %) and an increase in potential evapotranspiration (ET) (up to + 22 %). The latter is indicative of possible drought spells between rainy events. The SDE approach showed much more pronounced decrease of precipitation and water yield compared to the CORDEX approach. This difference could be attributed to the difference in spatial resolution of the two downscaling approaches. However, it is expected that the results of this study could assist in policy formulation to mitigate the negative impact of climate change in the region. [ABSTRACT FROM AUTHOR]

In this paper, the fictitious domain method with continuation by lower coefficients for the model of the atmospheric boundary layer is mathematically substantiated. The theorem of existence and uniqueness of the solution of the auxiliary problem of the fictitious domain method for the equations of the boundary layer of the atmosphere is shown. The practical part is considered - the spread of harmful impurities in the atmosphere from point sources, taking into account the inhomogeneity of the underlying surface on the basis of the atmospheric boundary layer model. [ABSTRACT FROM AUTHOR]

In this paper it is present the analysis of meteorological data onboard aircraft, because meteorological forecasts are not 100% accurate, therefore, meteorologists, through the careful scientific study carried out with the help of computer equipment they have the capacity to make the prediction of some meteorological models, of the tendencies and features with very good accuracy. Through complex system of meteorological services, government agencies and meteorological observers, as well as pilots but also other types of aviation professionals' benefit from this extensive database in the form of frequently updated weather reports and forecasts. These reports and forecasts allow pilots to be informed before taking decisions about the weather, and about the safety of the flight ahead, but also during a flight. [ABSTRACT FROM AUTHOR]

One of the impacts of climate change is an increase in the frequency and intensity of extreme rainfall events. This has very significant social and economic consequences for the affected areas (flooding, loss of life, destruction of infrastructure, etc.). Future trends indicate a further increase in extreme rainfall in the second half of the century, making the need for the timely and accurate forecasting of these phenomena more urgent than ever. However, despite the technological development of weather and climate models in recent years, there are still limitations in detecting the extremes, especially regarding the precipitation parameter. Extreme precipitation events show a link with temperature. The Clausius-Clapeyron (CC) equation, which relates temperature to saturation vapor pressure (es), is used to study the sensitivity of precipitation to temperature increase because it can estimate the increase in the available atmospheric water vapor with respect to temperature. Focusing on the Thessaloniki region in Greece, the aim of this paper is to investigate the applicability of the Clausius-Clapeyron relation to the scaling relationship between extreme precipitation intensity and surface air temperature. An additional attempt is also made to test the possibility of improving the underestimation that the reanalysis models exhibit in recording the extremes and in particular the ERA5 Land dataset. [ABSTRACT FROM AUTHOR]

The paper presents a web system of assessment and 16 days in-advance forecast of weather fire danger according to the modified method by V.G. Nesterov. The system is used to regulate the duties and responsibilities of regional forest protection agencies and is aimed at deciding on aerial observation of fire-hazard vegetation areas. Global Forecast System climate model is used as actual and forecasting weather data. The designed system comprises a relational database of weather data and 3D polygons (grounds), modules of data uploading and making up a catalogued storage, converting GRIB-files and data visualization by JavaScript API via the electronic Google Maps. The software checkout was done using the specimen of the fire season in 2019 inside the territory of the Jewish Autonomous Region and Khabarovsk Territory of the Russian Far East. [ABSTRACT FROM AUTHOR]

The representation of Arctic clouds in numerical weather prediction models is challenging, especially for mixed-phase clouds with both a liquid and ice phase present. This cloud type is frequently observed in the Arctic with a pronounced longevity. In this paper, measurements conducted during the Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) campaign, which took place in May/June 2017 northwest of Svalbard, Norway, are compared with the operational 'Atmospheric Model high resolution' configuration (HRES) of the Integrated Forecasting System (IFS), operated by the European Centre for Medium-Range Weather Forecasts (ECMWF). Instead of using cloud retrieval products from airborne remote sensing, the comparison is performed in the observational space of spectral solar irradiances reflected by the clouds. To allow such an analysis along the flight track at flight level, the operational ecRad radiation scheme of the IFS is used in offline mode. Besides the HRES model output, vertical profiles of concentrations of trace and greenhouse gases provided by the ECMWF Atmospheric Composition Reanalysis 4 serve as the input for ecRad. The ability of the IFS to realistically represent the airborne radiation measurements collected during ACLOUD is evaluated for flight sections above sea ice and open ocean. Based on the good agreement of the HRES output with common sea-ice concentration satellite products, the radiation measurements are not significantly biased by sea-ice fraction. A case study with boundary-layer clouds of changing cloud phase is investigated in detail and the impact of the ice cloud mass mixing ratio on the spectral irradiance is investigated. For the cloud dominated by ice crystals, the common ice optics parameterization applied in the ecRad simulations is tested against more advanced scattering databases. The ice optics parameterization from Baran et al. (2016) agrees closest to ACLOUD observations in the 778−1242 nm and the 1626−1942 nm band, the parameterization from Yi et al. (2013) agrees closest in the 1299−1626 nm band. [ABSTRACT FROM AUTHOR]

The aim of the presented paper is to analyze the 10-meter wind (U10) conditions of the western part of the Black Sea during the present and near future interval. More precisely, 10 locations were studied. Regarding the geographical location, the points of interest are located in the range 40oN to 47oN and 27oE to 34oE as follows: 2 points are near to the Ukraine's coast line, 3 to Romania's coast line, 2 to Bulgaria's coast line and 3 to Turkey's coast line. Thus, for analyzing the wind conditions during the present interval, two sets of data were taken into consideration. The first set was provided by the Regional Climate Model (EURO-CORDEX evaluation) for 30 years (01 January 1980 to 31 December 2009). The second data set was based on 30-year (01 January 1987 to 31 December 2016) hindcast information provided by NCEP-CFSR (National Centers for Environmental Prediction-Climate Forecast System Reanalysis). Regarding the near future analysis, 30-year (01 January 2021 to 31 December 2050) of data coming from the Regional Climate Model (EURO-CORDEX, scenario RCP4.5) were used. Finally, by analyzing the resulted data it can be concluded that the presented paper provides a more comprehensive picture regarding the present and near future of 10-meter wind conditions within the western part Black Sea. Some climatic trends can be also assessed. [ABSTRACT FROM AUTHOR]

Worldwide, the increased demand for various chemical products has led to an increased production activity of chemical plants involving the use of a large variety of chemicals. Most of the chemical substances used by the plants on a regular basis are considered to be highly hazardous, having toxic, explosive or flammable properties. The production, use, transportation or storage of such hazardous chemicals involves special occupational health and safety measures which have to be taken into account by the employers. In this case, improper OHS management measures can lead to unwanted events, caused for example by the accidental leakage of hazardous chemicals from storage tanks, and which can have catastrophic consequences for the employer, for the workers and the surrounding environment. For this purpose, companies have to develop emergency response plans which have as main purpose the minimization of hazardous effects. This paper addresses a possible scenario generated by the accidental leak of a hazardous chemical substance form a storage tank located within a chemical plant, analysed by means of state-of-the-art commercially available software tools for analysis and consequence determination of process hazards in the industry. The study reveals the influence of meteorological conditions on the discharge and the extent of toxic gas dispersion into the atmosphere. Also, there are studied several cases for different diameters of the release orifices, and the toxic concentration results are presented for the three ERPG (Emergency Response Plan Guide) levels [ABSTRACT FROM AUTHOR]

One primary step in preserving historical heritage against climate change is finding how this phenomenon affects the building material's hygrothermal performance. To study the such impact, a high-resolution and reliable climate model is required. The effect of the climate model's uncertainties on hygrothermal modelling is not well understood. This paper aims to evaluate two regional climate models, ALARO-0 and REMO2015, over northeastern Iran, employing HAM simulations to obtain more knowledge about the impact of the climate model uncertainties on hygrothermal modelling. The processing of the simulation results indicates that, despite the high accuracy of the analysed models for ambient temperature and precipitation, the outputs based on historical observations are significantly inconsistent with the model-based results due to the large bias of both models for wind-based parameters. The analysis recommends that a climate model evaluation using HAM simulations should be undertaken to avoid making incorrect predictions of future climate effects on building material degradation. [ABSTRACT FROM AUTHOR]

The CNES/DLR MERLIN satellite mission aims at measuring methane dry-air mixing ratio column (XCH4) and thus improving surface flux estimates. In order to get a 1% precision on XCH4 measurements, MERLIN signal processing assumes an averaging of data over 50 km. The induced biases due to the non-linear IPDA lidar equation are not compliant with accuracy requirements. This paper analyzes averaging biases issues and suggests correction algorithms tested on realistic simulated scenes. [ABSTRACT FROM AUTHOR]

Accurate measurements of the vertical profiles of atmospheric temperature are necessary to advance the knowledge of dynamics-thermodynamicsradiative interaction mechanisms triggering convection, and ultimately improve weather forecasting capabilities. Comprehensive intercomparisons between different remote sensing and in-situ sensors have to be carried for the purpose of obtaining accurate error estimates for these sensors. This paper reports results obtained in the frame of the Hydrological Cycle in the Mediterranean Experiment – Special Observation Period (HyMeX-SOP1). [ABSTRACT FROM AUTHOR]

This paper presents the results from a coordinated approach for atmospheric investigation, exploring synergies between different techniques. A wide range of instruments have been used during an intensive measurement period both from ground (lidar, sunphotometer, aethalometer and Aerosol Chemical Speciation Monitor) and airborne (aerodynamic particle sizer, the Picarro gas analyzer and the NO2 CAPS analyzer) in 2016 over Magurele, 6 km South West of Bucharest. [ABSTRACT FROM AUTHOR]

Air pollution and meteorological models are examples of mathematical models with a lot of natural uncertainties in their input data sets and parameters. Sensitivity analysis is a powerful tool for studying and improving the reliability of such models. In this paper we present the results of a global sensitivity study of the Unified Danish Eulerian Model (UNI-DEM). One of the most important features of UNI-DEM is its advanced chemical scheme the Condensed CBM IV, which considers a large number of chemicals, and various reactions between them, of which the ozone is the most important pollutant because it is used in many practical applications. The stochastic methods based on Faure and Sobol sequences are used for computing the sensitivity measures. The numerical experiments show that the stochastic algorithms for the multidimensional integrals under consideration are efficient methods for computing the small value sensitivity indices. [ABSTRACT FROM AUTHOR]

In this paper we present a development of novel algorithms and techniques implemented within the Laser Remote Sensing Laboratory (LRSL) of the National Technical University of Athens (NTUA), in collaboration with Raymetrics S.A., in order to incorporate them into a 3Dimensional (3D) lidar. The lidar is transmitting at 355 nm in the eye safe region and the measurements then are transposed to the visual range at 550 nm, according to the World Meteorological Organization (WMO) and the International Civil Aviation Organization (ICAO) rules of daytime visibility. These algorithms are able to provide horizontal, slant and vertical visibility for tower aircraft controllers, meteorologists, but also from pilot’s point of view. Other algorithms are also provided for detection of atmospheric layering in any given direction and vertical angle, along with the detection of the Planetary Boundary Layer Height (PBLH). [ABSTRACT FROM AUTHOR]

The ADM-Aeolus L2B horizontal line-of-sight wind products are discussed, including a brief introduction to the L2B processing methods. Realistic simulation of Aeolus followed by the Ground Segment processing chain is used to assess the expected error statistics of the L2B winds. Examples of the L2B winds simulated from realistic atmospheric cases are discussed. The aim of the paper is to give potential users an impression of the expected characteristics of Aeolus mission’s main product. [ABSTRACT FROM AUTHOR]

The mobile system described in this paper integrates a commercial eye-safe lidar (CIMEL), a sunphotometer and in situ instruments. The system is distinguished by other transportable platforms through its capabilities to perform onroad measurements. The potential of a commercial lidar to provide reliable information on aerosol properties is investigated through comparison with a multi-wavelength Raman lidar. First results from observation campaigns in northern France are presented. [ABSTRACT FROM AUTHOR]

This paper will report on the data collected by a Sigma Space Micropulse Lidar (MPL-111), and how these measurements, when integrated with other data, helps to inform our analysis of two cases of the Great Plains nocturnal Low-Level Jet (LLJ) in the vicinity of FP3. [ABSTRACT FROM AUTHOR]

The NASA GEWEX SRB project is moving toward the next generation, or Release 4, of its products as its algorithms are updated and new inputs from the ISCCP become available. This paper compares its early shortwave/longwave results with the surface-based BSRN, GEBA, WRDC as well as the PMEL data. The comparison statistics show that the new algorithms along with the new inputs appreciably improve the quality of the products. [ABSTRACT FROM AUTHOR]

Elements of Earth's cryosphere, such as the summer Arctic sea ice pack, are melting at precipitous rates that have far outpaced the projections of large scale climate models.Understanding key processes, such as the evolution of melt ponds that form atop Arctic sea ice and control its optical properties, is crucial to improving climate projections. These types of critical phenomena in the cryosphere are of increasing interest as the climate system warms, and are crucial for predicting its stability. In this paper, we consider how geometrical properties of melt ponds can influence ice-albedo feedback and how it can influence the equilibria in the energy balance of the planet. [ABSTRACT FROM AUTHOR]

This study aims to analyze future snowmelt runoff and snow extent for the Upper Euphrates Basin (41 109 km 2) which is the most upstream basin of the water tower Mesopotamia and located in the Eastern mountainous part of Türkiye. The future characterization of snowmelt runoff and snow water equivalent is investigated taking the regional climate model projections into account through hydrological model applications. The basin is divided into two major sub-basins Karasu Basin and Murat Basin. The conceptual hydrological models, HBV and HEC-HMS have been utilized to establish a rainfall-runoff relationship. The models are calibrated and validated with observed daily total precipitation and average temperature data for the 1980–2011 period. Future projections are selected for the 2025–2100 periods using EU-CORDEX data with various global circulation models. MPI-ESM-LR and CNRM-CM5 data sets and RCP4.5 and RCP8.5 emission scenarios are used for future projections. The results indicate a decrease in snow cover extent and an increase in snowmelt runoff. The overall assessment will help us to understand how these changes will affect the operations of water resources systems (downstream reservoirs) in terms of flood control, energy production, irrigation, water supply, etc. [ABSTRACT FROM AUTHOR]

This study was carried out in the White Bandama watershed (WBW) in Côte d'Ivoire (West Africa). The objective is to assess the impacts of future climate change (CC) on the hydropower potential (HPP) of the WBW. The methodology is based on coupling the SWAT (Soil and Water Assessment Tool) hydrological model with the Geographic Information System (GIS) QGIS to assess HPP on streams and evaluate the impacts of future CC on HPP of the watershed. Historical and climate projection data (precipitation, minimum and maximum temperature) for a set of three Regional Climate Models (RCM) from CORDEX-AFRICA (CCCma-CanRCM4, CCLM4-8-17 and REMO 2009) under RCP 4.5 were used. The biases of the ensemble mean were corrected by the Delta-change method. The relative change of streamflow discharge and HPP was assessed as the relative difference between the projection periods (2041–2070 and 2071–2100) and the reference period (1976–2005). The results showed a total of 22 future hydropower potential sites in the watershed. These sites were identified, geolocated and classified according to their potential capacity of generation in 82 % as small (1–25 MW potential capacity), 9 % as medium (25–100 MW potential capacity) and 9 % as large (more than 100 MW potential capacity) hydropower. The climate models' ensemble projected an upward trend for both the annual mean discharge of rivers and HPP of the WBW according to RCP 4.5 for the periods 2041–2070 and 2071–2100. On the annual cycle, the months of August and September will record the highest monthly mean flows between 150 and 200 m 3 s -1 while the months from November to April will record low monthly mean flows in the WBW. [ABSTRACT FROM AUTHOR]

Uncertain climatic projections result in uncertain runoff predictions, which lead to unreliable water resources management and floods mitigation measures. This study investigates runoff uncertainty associated with Global Climate Models (GCMs) chosen as boundary conditions in regional climate models (RCMs). To this end, the study projected surface air temperature, precipitation, wind speed, and potential evapotranspiration, over Qatar, from the Massachusetts Institute of Technology (MIT) RCM driven by three GCMs: CCSM4, MPI-ESM, and NorESM. Historical projections were made during 1976–2005 while future projections were made during 2071–2100 under the business-as-usual Representative Concentration Pathways (RCP8.5). The study then inputs climatic parameters in addition to topographic and groundwater data, in a physically based water balance model to compare runoff simulations. During historical and future periods, climatic projections differed among the RCM runs, especially precipitation and potential evapotranspiration. Uncertainty in climatic projections caused significant uncertainty in runoff estimations. Runoff estimations varied from 12.2 to 45 Mm 3 yr -1 , with an average value of 24.4 Mm 3 yr -1 during 1976–2005, and from 12.3 to 52.4 Mm 3 yr -1 , with an average value of 32.4 Mm 3 yr -1 during 2071–2100. All RCM runs agreed on future runoff increases. Since runoff is a main cause of floods and alleviating flood risk can be hindered if climatic projections are incompetent, the study's findings emphasize on narrowing the uncertainty in GCM projections. The study also encourages Qatar authorities to implement managed aquifer recharge projects like rainwater harvesting to alleviate floods risk. [ABSTRACT FROM AUTHOR]

The article presents numerical modeling of meteorological processes in the wind farm of the Republic of Adygea. The wind farm has 60 wind turbines, the capacity of each wind turbine is 2.5 MW. A test configuration with 4 nested domains was developed to study the wind farm. The computations were carried out using the WRF-ARW computational code with the wind turbine parameterization module. The calculation was performed for the period 01.04.2020 00:00 – 01.05.2020 00:00 UTC. As a result, the dimensions of the wake formed by the wind farm were obtained, and the influence of the parameterization of wind turbines on the wind distribution calculation was shown. The potential vortex wake can reach sizes up to 15 km. The losses of generated power can reach 1 MW inside the vortex wake. The computations were run on high performance cluster UNIHUB of ISP RAS. [ABSTRACT FROM AUTHOR]

The objective of this paper is to analyze the performances (capacity factor, rated capacity, operating capacity, annul electricity production) of some of the most used wind turbines in nearshore and offshore operations. The target area of this study is the Black Sea. More precisely, twelve points were chosen for this analysis. The wind fields (zonal and meridional velocity at 10-meter height) from four datasets were used to assess the wind turbines performances. The first one is ERA-Interim. This dataset is a global atmospheric reanalysis database witch comes from ECMWF (European Centre for Medium-Range Weather Forecasts). From this dataset 31-year period of data (1 January 1980 to 31 December 2010) were used. The other three datasets come from EURO-CORDEX experiment. This project contains high-resolution wind fields produced by various RCMs (Regional Climate Models). The first data set from EURO-CORDEX, representing the evaluation (hindcast), covers a period of 31-years (01 January 1980 to 31 December 2010). The last two are those simulated by Regional Climate Models under future climate projections under two Representative Concentration Pathways scenarios (RCP4.5 and RCP8.5) that cover the time interval from 01 January 2021 to 31 December 2050. [ABSTRACT FROM AUTHOR]

Observations of atmospheric CO2 concentration profiles provide significative constraints on the global/regional inversions of carbon sources and sinks. Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences developed a Raman Lidar system to detect the vertical distribution of atmospheric CO2. This paper compared the observations with the modeled results from a three-dimensional global chemistry transport model-GEOS-Chem, which showed a good agreement in the trend of change with lidar measurements. The case study indicated a potential for better simulating vertical distribution of atmospheric CO2 by combining with lidar measurements. [ABSTRACT FROM AUTHOR]

The article provides an analytical review of Russian and foreign sources on the problem of interaction of wind turbines with the surface layers of the atmosphere. The main problems of mathematical modeling of the atmospheric boundary layer in the vicinity of wind farms, associated with difficult meteorological conditions with constant zero crossings in the autumn-winter period, various precipitation, a wide time range, air parameters, terrain and other features have been identified. The analysis of the evolution of mathematical models of turbulence to describe the boundary layer near wind turbines, from earlier to actively developing and currently used. To achieve greater accuracy and naturalism, it is proposed to use high-performance efficient algorithms based on combining scales and physics of phenomena. In the article, the authors proposed a mathematical model for studying the state of the atmospheric polydisperse boundary layer in the conditions of the Ulyanovsk wind farm, considering the presence of dispersed particles in the flow, surface curvature, pressure gradient and other influences. [ABSTRACT FROM AUTHOR]

Air pollution modeling has attracted experts in the field of the atmospheric environment due to its priority in future studies. In general, many studies conducted to model air pollutants such as proximity models, geostatistical interpolation, dispersion models, land use regression models, remote sensing, and artificial intelligence models. In this study, we review studies that are relevant to the modeling of air pollutants. We qualitatively and quantitatively evaluated these studies. Proximity models are considered the most basic methods to assess the quantitative, temporal, and spatial variation of air pollutants in a specific area. The main drawbacks of this technique, proximity models often use a limited number of parameters like traffic and roads neglecting important parameters such as weather information, and topography. In addition, these models neglect the type of vehicles like trucks and vehicles. Moreover, these models need self-reported approaches that represent the exposure to pollutants emitted from traffic, which may have been affected by biased information. On the other hand, this approach is usually performed based on the geostatistical interpolation techniques or GIS modeling, the main advantage of this method is; the precision of maps mainly relies on the accuracy of the used dataset and the interpolation algorithm used in GIS. Land use regression models are well-known models that use multiple linear regression algorithms to model the relationship between the dependent variable and independent variables. The main constraint of these models that they are difficult to be generalize for other study areas that include different natures. Dispersion models are important models that used various kinds of parameters such as emission data, topography, and meteorological data to model pollutants emissions in ambient air. The most recent approaches are the remote sensing methods that are used to detect and monitor air pollutants concentrations over large areas. The main drawbacks of remote sensing methods are that they are not suitable for high-resolution predictions in urban scales such as micro-scales studies. The most advanced techniques are artificial intelligence algorithms due to their ability to allow computer applications through learning from experience based on algorithmic training and iterative processing. This study can be a good guideline for researchers who are interested in the modeling of air pollutants. [ABSTRACT FROM AUTHOR]

The most extreme manifestation of a fire-weather interaction is the formation of pyrocumulonimbus (pyroCb) thunderstorms, triggered by super-heated updrafts, which can eject smoke at altitudes exceeding 20 Km. In this study, we investigated climate-related impacts from the most intensive pyroCb-triggered injection of smoke in the stratosphere: the Australian New Year wildfires in 2019/2020. We first provide a general overview of the vision and objectives of the StratoFIRE project. With the aid of the global chemistry-climate model EMAC, we then simulate radiative and chemical perturbations in the stratosphere in relation to 0.9 Tg smoke in the stratosphere assuming different injection heights, from 13 to 16 Km. The simulation of stratospheric optical depth perturbations were found to be sensitive to the assumed injection height, with a maximum height at 16 Km showing the best agreement with the GLOSSAC and SAGE-ISS aerosol extinction observations. [ABSTRACT FROM AUTHOR]

An increase in the frequency of wildfire occurrence is predicted in all climate model estimates, implying significant health impacts, due to the emission of combustion products. Application of pollutant dispersion models at strategic and operational levels is imperative for safety reasons and for compliance with European Civil Protection Mechanism policies. Here, we describe the dispersion of smoke from the forest fire of Penteli-Attica (Greece) on 19 July 2022, which burnt a total area of 2781.7 hectares. High-resolution dispersion simulations, air-quality measurements, and remote sensing observations are used to describe the transport of smoke and facilitate effective smoke control in areas where air quality impacts are likely to be significant. [ABSTRACT FROM AUTHOR]

In the present study, the spatial and temporal variability of the Aridity Index (AI) in the Mediterranean region during the 30-year period 1971-2000 is analyzed. The analysis is performed on a decadal timescale. Subsequently, the projected change in the AI in the periods 2031-2060 (near future) and 2071-2100 (far future) under the RCP4.5 and RCP8.5 emission scenarios in comparison with 1971-2000 (reference period) is presented. The input of the calculations are simulation results supplied by the CORDEX EU project. In total, an ensemble of 20 combinations of global climate models (GCMs) and regional climate models (RCMs) are used. The calculation of the AI is based on potential evapotranspiration, which, in turn, is calculated according to the classic method of Thornthwaite. Our results show that drier conditions are to be expected in the future along a wide zone in southern Europe, including Spain, Italy, Bulgaria, Greece and Turkey, as well as in Northern Africa, particularly under the RCP8.5 scenario and towards the end of the century. [ABSTRACT FROM AUTHOR]

Data assimilation is a technique used to combine observational data with numerical weather analysis fields to produce input conditions for Numerical Weather Prediction (NWP) models aimed at more accurate forecasts. In this study, two different regional Background Error (BE) covariance statistics are evaluated for the implementation of a Weather Research and Forecast (WRF) model using Variational Data Assimilation (VAR) schemes. Two different WRF model forecasts, initialized at different times, are compared to calculate different regional BE statistics based on the National Meteorological Center (NMC) technique. These statistics are then used in the three-dimensional variational (3DVAR) data assimilation process to produce analysis fields for a 15 day period during September 2019. The study compares the forecasts produced using the two different BE statistics and presents the results of the analysis fields during the medicane "Ianos" formed in September 2020 in the eastern Mediterranean Sea. The study demonstrates the importance of BE statistics' usage in data assimilation. The results suggest that different initialization times can lead to significant differences in weather evolution. The study also highlights the need for caution in the choice of BE statistics and the importance of best practices in data assimilation. [ABSTRACT FROM AUTHOR]

Heating and Cooling Degree Days (HDD, CDD) are indicative of the energy needs of buildings and also are associated with agriculturalism, tourism and other outdoor activities. Under the changing climate, future modifications of HDD and CDD are of primary importance. In the present work, monthly and annual HDD and CDD are computed and analyzed for the present and near future climate conditions. Elevation and sea proximity were found to be crucial in the formulation of energy requirements. Summer energy needs for cooling are expected to increase due to global warming while winter needs for heating are expected to decrease. [ABSTRACT FROM AUTHOR]

Aerosols, ozone, surface reflectivity, and clouds are, among other factors, important for the modulation of UV radiation levels at the Earth's surface. In this study, these variables were extracted from climate model integrations that contributed to CMIP6 and from MACC global reanalysis provided by the CAMS. From the 1950s until the end of the 21st century and for various shared socioeconomic pathways considered by CMIP6, we conclude that total ozone will increase globally in 2100 by up to 11% under SSP5-8.5 relative to the 1950s, while under SSP1-2.6, ozone is not projected to recover to pre-ozone depletion levels. AOD at 550 nm shows reductions in 2090-2100 over the Northern Hemisphere of up to -0.38. Compared to CAMS, CMIP6 models show a general overestimation for total ozone of up to 2.5% in extra-polar regions for models with interactive chemistry. This implies systematically lower UV radiation from models based on these projections. [ABSTRACT FROM AUTHOR]

Weather conditions affect the microclimate of architectural monuments. The alteration of microclimate conditions may create risks for monuments, accelerating their weathering process. For Greece, hosting numerous monuments, the identification of the risks that climate change possess is essential for planning mitigation actions. The main soluble salts that affect archaeological materials are halite and the system of thenardite/mirabilite. The thermodynamics of the salts' equilibrium are affected by atmospheric conditions. We study the climatology of these conditions, adopting modeled data produced by high-resolution simulations. Possible climate change impacts are investigated, aiming at mapping monuments' vulnerability in Greece. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the response of the rational method in flood hazard assessment in Potamia watershed of Thasos island, with climate data from Regional Climate Models. The precipitation intensity-duration-frequency (IDF) curves used were calculated using available EURO-CORDEX 0.11 regional climate model simulations, under the RCP8.5 scenario. The Corine Land Cover dataset was utilized for the determination of the runoff coefficient of the watershed and geomorphological and hydrographic characteristics are calculated using a Geographic Information System software. A comparison against actual flood events of the period 1991-2019, as mapped with satellite Synthetic Aperture Radar (SAR) imagery, is also carried out. [ABSTRACT FROM AUTHOR]

During the last few years, extremely high temperatures have been recorded in many Greek regions and, in some cases, have been rather abnormal for each season. These extreme events appear to be persistent in duration and are occurring at a disconcerting frequency. The main objective of this study is to examine the exceptionally high temperatures that were recorded during January 2023 in Thessaloniki, Greece. The entire month was characterized by minimum and maximum temperatures that exceeded the climatological mean (1961-2000) by about 4.2 °C on average. Additionally, the average deviation for the mean maximum temperature of the month was calculated at 3.5 °C. In an attempt to classify the intensity of this possible extreme event compared to a future intermediate emission scenario (RCP4.5), a comparison of the observational data with the corresponding data from two future projections (2041-2060 and 2081-2100) of a high-resolution regional climate model was carried out. The spatial resolution of the simulations was 10 x 10 km and they were the result of the dynamical downscaling of the RegCM regional climate model after nesting a 25 km simulation of the model for the initial and boundary conditions. Finally, through this study, the contribution of the synoptic-scale atmospheric conditions of this event was examined. [ABSTRACT FROM AUTHOR]

In this work, the Max Planck Institute for Meteorology Grand Ensemble (MPI-GE) is used to quantify the climate system's internal variability. The MPI-GE is a large ensemble of a single state-of-the-art comprehensive climate model and its use is crucial to evaluate average changes in summer monthly means and extreme temperatures. Initially, model simulations are examined in terms of their ability to accurately reproduce the observed climatic regimes in the Mediterranean region for the historical period. The ERA5 reanalysis dataset is employed as a reference and the corresponding trends and frequencies of occurrence of temperature-extreme events are compared between these datasets. Subsequently, the MPI-GE is used as a tool for examining the effect of the climate system's internal variability focusing on the Mediterranean summer temperatures under different levels of global warming. Understanding and decoupling the effects of internal variability and anthropogenic forcing on climate trends remain a key challenge. It is found that in the rcp8.5 scenario, the frequency of summer extreme temperatures is higher than that in the rcp2.6 scenario. Especially in the Greek region, the frequency is 1.5 times higher in rcp8.5 than in rcp2.6 [ABSTRACT FROM AUTHOR]

This study aims at assessing meteorological, hydrological, and hydraulic modeling to develop a flash flood forecasting tool. The flash flood that occurred in the Evrotas River Basin (ERB) on 26 January 2023 is used as a case study. Precipitation over 150 mm and water depths exceeding 2.5 m were recorded. The meteorological model initialized one day before flooding and simulated precipitation; the hydrological model, using meteorological input data, simulated discharge; and the hydraulic model, using discharge, estimated water depth at a bridge. The results indicate that the system can provide skillful and timely flash flood forecasts, thereby facilitating flood warnings. [ABSTRACT FROM AUTHOR]

We investigate future changes of agro-climatic zones over Europe under two different IPCC Representative Concentration Pathways (RCP4.5 and RCP8.5) based on an ensemble of 11 bias-corrected regional climate model simulations covering the period 1981-2100. Eight distinct agro-climatic zones were identified by applying the k-means clustering method for the reference period 1981-2010 on two temperature-related parameters: the growing season length and the active temperature sum. Our results point towards a strong northward shift of the agro-climatic zones, especially under RCP8.5, towards the end of the century. A significant shift of the agro-climatic zones is also projected for RCP4.5 in the near-future and the end-of-the-century periods for large areas in Europe. [ABSTRACT FROM AUTHOR]

Climate change (changes in temperature and weather patterns) plays a significant role in the outbreak of tick-borne diseases such as Lyme borreliosis (LB) disease and tick-borne encephalitis (TBE) in Europe. The prevalence of LB disease has increased lately and TBE, one of the most serious infections of the central nervous system, significantly affects public health. Changes in abiotic factors are the main determinants affecting their vectors. The warmer weather during winter has prolonged the extension of the period in which ticks are most active. Therefore, the increased risk of transmission of tick-borne diseases influenced by the climate conditions could be determined by advanced climate models. [ABSTRACT FROM AUTHOR]

Climate models are fundamental tools for assessing historical climate conditions and projecting future ones. However, the results often differ systematically from observational data. The minimization of these differences is known as bias correction. The present study aims to correct the biases between observed daily precipitation values and the respective simulated ones from a EURO-CORDEX climate model. For this purpose, powerful statistical tools--generalized additive models (GAMs)--are used. GAMs are modified to adjust the simulated rainfall with the highest accuracy, and subsequently, they are evaluated by comparison with observational data. The method was applied to two eastern Mediterranean stations (Larissa in Greece and Larnaca in Cyprus) for the period 1981 to 2005. The results from both stations reveal that GAMs offer a valuable and accurate technique for the bias adjustment of daily precipitation. [ABSTRACT FROM AUTHOR]

The objective of this study is to improved inferences for a model of observed extreme data by linking the distributional of observed data with a climate change model data. We exploit the extra information from projection data of the climate models (RCM and GCM) for the period 1970-2099 under emission scenarios RCP8.5 in.modelling an annual extreme rainfall that collected from 44 stations in Sabah. The joint model enables additional information about the trend from longer records of climate model to be incorporated with the limited observed extreme data at each site. The proposed models were built based on the independent likelihood over sites therefore the standard error of the parameters need to be adjusted to take into accounts the inter-site dependence. As a result, we found a common trend between the observed data and climate model and the sandwich estimator reduces the variances of the marginal characteristics and yield more accurate inferences. [ABSTRACT FROM AUTHOR]

The aim of this study is to present preliminary results of testing the new non-hydrostatic dynamic core of the regional climate model RegCM4.7.1 by varying different parametrization schemes over the Balkan Peninsula and Bulgaria. A one-way double nesting technique was applied, employing a mother domain with 15 km grid spacing and a nested domain with 3 km grid spacing. Twenty test simulations were performed with a model resolution of 15 km for the year 2000 on a Lambert Conformal Conic projection and 12 test simulations with a model resolution of 3 km for one month-January 2000. Two planetary boundary layer schemes (UW PBL and Holtslag), four cumulus schemes (Emanuel, Grell, Tiedke and Kain-Fritsch), three explicit moisture schemes (Nogherotto-Tompkins, WSM5 and SUBEX) and two shallow convection configurations (MM5 and Tiedke) were tested. We used ERA-Interim reanalysis as boundary conditions for the 15 km runs with 0.75-degree horizontal resolution. The results are presented for several model output parameters (precipitation, temperature, surface pressure and cloud fraction cover). The output is compared with E-OBS observational dataset, satellite-based observations and ERA-Interim reanalysis. Based on the results, the model is sensitive to the choice of different parametrization schemes. The 15 km simulations overestimate the precipitation and underestimate the temperature in all scheme configurations. The biggest biases in precipitation and surface pressure we found in simulations with combinations with Nogherotto-Tompkins moisture scheme. In the case of 3 km simulations, UW PBL scheme with WSM5 moisture configurations and Nogherotto-Tompkins configurations gave the largest biases for the studied territory. [ABSTRACT FROM AUTHOR]

Model turbulent degenerate diffusion equations of passive contaminant emitted from elevated continuous source into the atmosphere are studied. Here, we consider two models with power law functions eddy diffusivity profiles and wind velocity profiles of similar character. Well-posedness, i.e. existence of a unique solution, of variational formulations of the forward equations is subsequently studied. In each of these cases, we exhibit the corresponding evolution triple (Gelfand triple) consisting of a (weighted) L2 space, identified with its own dual and the domain of the bilinear form. [ABSTRACT FROM AUTHOR]

The work considers the method of compiling a model for the distribution of the duration of standing parameters of the outdoor climate during the average year. The method is based on the presentation of discrete statistics on the distribution of observations of the combination of temperature and relative humidity of outdoor air at certain intervals of their values in the form of integral characteristics. The latter are represented by a system of mathematical functions, which in turn are summarized into one equation, representing a mathematical model of the distribution of the duration of the standing of a combination of specified values of climate parameters. The proposed method can be implemented for any geographical location, if there are statistical distributions of the parameters of the standard kind of climate. The outdoor air distribution model can be useful for analysing the operation of building microclimate systems in order to select a rational design and operating modes. [ABSTRACT FROM AUTHOR]

Passive radiative cooling is a promising field in energy conservation and environmental protection. Radiative cooling includes technologies and design features developed for cooling buildings with minimal energy consumption and can significantly contribute to the limit of global warming when implemented on a large scale. In recent years, several new high-emission materials have been proposed that enabled the radiative coolers to provide an average daily cooling power of around 100 W/m2 during the daytime. Based on the developed mathematical model, the multi-layer coating optical properties for the radiative cooling system evaluated by the Transfer Matrix Method, and the effectiveness of radiative cooling due to using a multi-layer coating determined in the climatic conditions of Syria (Latakia). The results of modeling the atmospheric transmittance and solar radiation in the summer in Syria (Latakia) are presented. The maximum cooling power of the multi-layer coating was 37 W/m2 at night during the summer. The multi-layer coating surface temperature at night is about 3 degrees below the average ambient temperature. The methods presented in this study for modeling atmospheric transmittance, calculating solar irradiation, evaluating the multi-layer coating optical properties allow determining the effective multi-layer coating for daytime radiative cooling systems in any climatic conditions. The methods presented in this study for modeling atmospheric transmittance, calculating solar irradiation, evaluating the multi-layer coating optical properties allow determining the effective multi-layer coating for daytime radiative cooling systems in any climatic conditions. [ABSTRACT FROM AUTHOR]

The objective of this study is to model the Mono River basin at Athiémé using stochastic approach for a better knowledge of the hydrological functioning of the basin. Data used in this study consist of observed precipitation and temperature data over the period 1961–2012 and future projection data from two regional climate models (HIRHAM5 and REMO) over the period 2016–2100. Simulation of the river discharge was made using ModHyPMA, GR4J, HBV, AWBM models and uncertainties analysis were performed by a stochastic approach. Results showed that the different rainfall-runoff models used reproduce well the observed hydrographs. However, the multi-modelling approach has improved the performance of the individual models. The Hermite orthogonal polynomials of order 4 are well suited for the prediction of flood flows in this basin. This stochastic modeling approach allowed us to deduce that extreme events would therefore increase in the middle of the century under RCP8.5 scenario and towards the end of the century under RCP4.5 scenario. [ABSTRACT FROM AUTHOR]

Nowadays, special attention is paid to hydroelectric production because it is an efficient, reliable, and renewable source of energy, especially in developing countries like Cameroon, where hydropower potential is the main source of electricity production. It also represents a useful tool to reduce the atmospheric greenhouse gas concentrations caused by human activities. However, it is the most sensitive industry to global warming, mainly because climate change will directly affect the quality, quantity of water resources (streamflow and runoff), which are the important drivers of hydropower potential. This study examined the response of hydropower potential to climate change on the Lagdo dam located in the Benue River Basin, Northern Cameroon. Hydropower potential was computed based on streamflow simulated using HBV-Light hydrological model with dynamically downscaled temperature and precipitation from the regional climate model REMO. These data were obtained using the boundary conditions of two general circulation models (GCMs): the Europe-wide Consortium Earth System Model (EC-Earth) and the Max Planck Institute-Earth System Model (MPI-ESM) under three Representative Concentrations Pathways (RCP2.6, RCP4.5 and RCP8.5). The results suggest that, the combination of decreased precipitation and streamflow, increased PET will negatively impact the hydropower potential in the Lagdo dam under climate change scenarios, models and future periods. [ABSTRACT FROM AUTHOR]

The impact of climate change on precipitation and water availability is of major concern for policy makers in the Mono Basin of West Africa, whose economy mainly depends on rainfed agriculture and hydropower generation. The objective of this study is to project rainfall, flows and evapotranspiration (ET) in the future period and understand their changes across Mono River Basin. Observed data were considered for the historical period 1980–2010, and a Multi-model ensemble for future projections data of eight selected Regional Climate Models under RCP 4.5 and RCP 8.5 over the periods 2011–2100 was used. The GR4J model was used to simulate daily flows of the Mono watershed. The ensemble mean shows a decrease and increase streamflows between -54 % and 42 %, -58 % and 31 %​​​​​​​ under the RCP4.5, RCP8.5 scenario, respectively. The greatest decreases of high flows is projected to occur in the near term under RCP8.5, whereas the greatest decrease of low flows is projected to occur in the long term under the same RCP. For the rainfall and ET, the both scenarios (RCP4.5 and RCP8.5) predict an increase of ET while the rainfall will decrease. The results of this study of would be very useful in the choice of management and adaptation policies for water resources management. [ABSTRACT FROM AUTHOR]