Alexandru Dumitrescu

Meteo Romania | METEOROMANIA · Department of Climatology

Daily records of nine meteorological variables covering the interval 1961–2013 were used in order to create a state-of-the-art homogenized climatic dataset over Romania at a spatial resolution of 0.1°. All meteorological stations with full data records, as well as stations with up to 30 % missing data, were used for the following variables: air pre...

Daily and sub‐daily homogenization of climate variables have been intensively investigated in the last decades, but to the best of our knowledge, this is the first study on homogenization of hourly temperature in Romania. This paper describes the creation of a homogenized hourly air temperature data set at a country scale by combining data from fou...

A reliable and practically useable method for gap filling in hourly Spinning Enhanced Visible and Infrared Imager (SEVIRI LST) data using ERA5 Land Skin Temperature (ERA5ST) co-variate and additional easily accessible data (elevation, time, solar radiation info) is proposed. The suggested approach provides estimates to all weather conditions and it...

A new and general approach is proposed for interpolating 6-h precipitation series over large spatial areas. The outputs are useful for distributed hydrological modelling and studies of flooding. We apply our approach to large-scale data, measured between 2014 and 2016 at 159 weather stations network of Meteo Romania, using weather radar information...

Four climate parameters (i.e. maximum, mean and minimum air temperature and precipitation amount) from 10 regional climate models, provided by the EURO-CORDEX initiative, are adjusted using as reference the ROCADA gridded dataset. The adjustment was performed on a daily temporal resolution for the historical period (1971–2005), as well as for clima...

In the past, long-term recordings of solar radiation energy were not commonly conducted. However, several observations using the Arago-Davy actinometer were made in different parts of the world during the nineteenth century. In this paper, we propose a method to convert actinometric degree data into information on global solar irradiance on a horiz...

The response of the cryosphere to a warmer climate is spatially diversified and requires accurate monitoring and understanding. The study analyses the changes in snow cover phenology (the first and last snow cover days - FSC and LSC), duration (SCD, SCDmax) and snow-free days (SFD) in Romania, which includes wide parts of the Carpathian Mountain ra...

Over the last decades, climatic changes have triggered considerable impacts across the globe with detrimental effects on all ecosystems. Given the complexity of topography and climate, Romania is one of the most exposed countries in the South‐Eastern Europe to extreme hydrological events. As a consequence, the spatial distribution of precipitation...

In this study, we consider the historical climatological time series available in the meteorological yearbooks of the Royal Hungarian Central Institute of Meteorology and Earth Magnetism, first published in 1871. Data quality improvement of historical data includes the homogenization process with outlier checks and data gap filling by applying the...

Monthly averaged daily global solar irradiation data collected from four online platforms (NASA POWER, MERRA2, ERA5 and CAMS) are compared with ground measured data retrieved from World Radiation Data Center and Baseline Surface Radiation Network. Similarly, monthly averaged daily global solar irradiation estimated by five different Ångström-Presco...

The output extracted from CNRM, MPR, and ICHEC Global Circulation Models for RCP 4.5 and RCP 8.5 Representative Concentration Pathways has been used in conjunction with the SWAT model for evaluating the impacts of future climate changes on hydrological processes in a Romanian catchment (Neajlov, 3720 km2 area) in the short (2021–2050) and long term...

Natural hazards, including droughts, are processes and phenomena that can trigger a negative impact on the environment, society and various economic sectors. The present chapter aims to identify spatial peculiarities of drought characteristics (frequency, duration, affected area) and to analyse drought hazard, vulnerability and risk in the Lower Da...

The Ångström–Prescott equation defines generically the relationship between solar energy available at ground level and sunshine duration. From the very beginning in the history of the solar energy converters, the equation was extensively used to estimate the amount of collectable solar energy. In the present paper, we propose a different way of loo...

This article provides the first country-scale climatology of the Surface Urban Heat Island (SUHI) investigated across the cities with more than 30,000 inhabitants from Romania using using the MODIS Land Surface Temperature (LST) data set developed within the Land Surface Temperature Climate Change Initiative (CCI) project (LST_cci), funded by Europ...

Fog is an important atmospheric phenomenon highly relevant to ecosystems and/or the environment. Two essential prerequisites of fog formation are the presence of fog condensation nuclei and water in the atmosphere. The aim of our study was to examine in detail how fog occurrence is influenced by water areas in the immediate vicinity of the fog obse...

The book aims to serve as a guidance tool for users of climate services and decision makers involved in planning sustainable adaptation to climate change. Also, we hope to provide a source of information on climate change and related risks for general public to raise the awareness on the need to mitigate and adapt to climate impacts.

The PannEx is a GEWEX-initiated, community driven research network in the Pannonian Basin. One of the main scientific issues to address in PannEx is the investigation of precipitation extremes. Meteorological Services in the PannEx area collected the hourly precipitation data and commonly used a computer program, which was developed in the INTENSE...

This study analyses long‐term changes in drought indices (Standardised Precipitation Index – SPI, Standardised Precipitation–Evapotranspiration Index – SPEI) at 1 and 3 month scales at 182 stations in eleven central and eastern European countries during 1949–2018. For comparative purposes, the necessary atmospheric evaporative demand (AED) to obtai...

Wind speed is involved in multiple scales physical phenomena and depends on specific features, that are not always easy to simulate numerically. Alternative solution that combines the physical advantages provided by numerical weather prediction (NWP) simulations and statistical models is investigated for wind speed forecast. Several aspects that in...

Fog is influenced by numerous factors, including forests. The aim of our study was to examine in detail the extent to which forests affect fog. We hypothesised that: (i) fog incidence is affected by forests, (ii) the forested area in the station’s neighbourhood is a factor influencing fog incidence, (iii) the influence on fog differs between conife...

The main goal of this paper is to infer local-scale information on future changes in a complex index quantifying the direct discomfort felt by the human body under global warming. A statistical downscaling model based on the canonical correlation analysis (CCA-SDM) is used to project future changes in heat thermal stress (THI) at high spatial resol...

This paper investigates the elevation‐warming relationships across the Carpathian Mountains, using the 0.1° × 0.1° gridded daily air temperature dataset developed within the CARPATCLIM project, in order to understand the spatial patterns of annual and seasonal temperature trends and test the hypothesis of enhanced warming with elevation. Temperatur...

Fog is a very complex phenomenon, relevant to both atmospheric physics and chemistry, contributing to the atmospheric inputs of both nutrients and pollutants to the environment. Fog occurrence is affected by numerous factors. The aim of this study is to examine the effects of terrain on fog occurrence. Namely, we studied in detail how altitude, slo...

With all the progress made in atmospheric modeling, the cloud field parameterization is still a critical issue. The present study proposes a new model for the probability of a clear-line-of sight (PCLOS). The great benefit of the proposed model is in the estimation of the effective cloud field parameters (namely, the cloud aspect ratio and cloud fa...

The Landsat 8 satellites have retrieved land surface temperature (LST) resampled at a 30-m spatial resolution since 2013, but the urban climate studies frequently use a limited number of images due to the problems related to missing data over the city of interest. This paper endorses a procedure for building a long-term gap-free LST data set in an...

Data recovery and climate reconstruction are an important support for climate change research, as they provide information from periods and areas with sparse meteorological networks. Various sources are currently in use for obtaining valuable evidence of past climate, such as ship logs, diaries, books monastery documents. This study exploits newspa...

This study has analysed the development of the urban heat island (UHI) under various synoptic scale atmospheric circulation for two large cities – Prague in central Europe and Bucharest in south-eastern Europe, including seasonal differences and long-term changes. At the best of our knowledge, it is the first comparison between two European cities...

It is already a well-known fact that air-temperature is the most important climatic factor of differentiation between intra- and extra-urban areas, mainly due to the characteristics of the underlying active surface. Bucharest town-area is no exception to the rule. Ranking as Romania’s largest city, its air-temperature singularities and differences...

Studies regarding species distribution, resilience and adaptability of different ecosystems as well as the response of human society are linked with our ability to identify past and predict future changes. Climate change together with other changes like land use and land cover, and invasive alien species, are important to set up the background for...

Snow water equivalent (SWE) and snow depth (SD) is estimating using Snow 17 model for several meteorological mountain station from Romania. The model uses air temperature as the sole index to determine the energy exchange across the snow-air interface. In addition to temperature, the only other input variable needed to run the model is precipitatio...

An increasing plethora of both meteorological and ancillary data are presently available for climate research and applications in urban areas. The data are often held by local or national institutions (i.e. meteorological services, universities or environmental agencies). This paper outlines a total number of 33 datasets, organized into three main...

In recent decades, water scarcity has become a frequent and widespread phenomenon. Intensification of water scarcity will have economic impact on the main water-using sectors. The highest pressure on the water resources is exerted by agriculture. Irrigation is the largest consumer of the agriculture sector and the efficient use of water is of utmos...

The sunshine duration data is analysed here from a new perspective, different from the traditional ones. The study is focused on pairs of periods of shining sun (called clear periods) followed by periods with the sun covered by clouds (called dark periods). Their statistical and sequential properties are illustrated by using results obtained from s...

This study presents the meteorological information spanning the last two decades of the end of 19th century (1880-1900) extracted from three Romanian newspapers (România Liberă, Gazeta de Transilvania and Foaia Poporului). It describes the characteristics of the newspaper data included in the database, it offers and overview of the meteorological n...

Five provenance tests with twenty-six European silver fir autochthonous populations were used in order to assess the response of populations to climate change. Height growth and diameter at breast height of trees at age 31 years were considered as response variables and eight climate variables as predictors. Climatic variables for the trial sites a...

This study proposes a simple methodology for assessing future-projected evolution of water cycle components (precipitation, potential evapotranspiration, and potential runoff) based on the two-level Palmer model of the soil and their impact on drought conditions at basin level. The Palmer Drought Severity Index (PDSI) is used as drought metric. Th...

In the spring of 2007, 51 full-sib and six half-sib families of European silver fir were obtained through controlled and open pollinations from the same clones in a seed orchard. Genetic variation and parameters for bud flushing were de- termined in two progeny tests established in a nursery. The results indicate a high genetic control of bud flush...

Precipitation: Measurement, Climatology, Remote Sensing, and Modeling (co-organized)

This study presents the spatial interpolation procedure from snow depth measurements at weather stations implying the following stages: (1) Spatial interpolation at 1 km × 1 km resolution of the mean multiannual values (2005-2015) corresponding to each month, computed from the data extracted from the climatological database; (2) Computation of the...

Urban settlements induce major disturbances in the regional climate and generate particular living conditions for the population. The high heterogeneity of the urban environment gives rise to a corresponding mixture of intra-urban climate characteristics, depending on factors like meteorological context, urban geometry and land cover/land use. Intr...

We propose a new index for quantifying the maximum rain intensity (IMAX) within a rainfall event. The goal of this paper is 2-fold: first, to analyse the characteristics of variability (trends, change points) for maximum values of this index calculated for spring (April-May), summer (June-August) and autumn (September-October) in comparison with ot...

The crop evapotranspiration computing is a complex matter from many points of view, but also it represents a useful parameter in hydrological and climate studies. Due to climate changes, the natural systems are coming to be negatively affected. The seasonal and annual crop evapotranspiration under current climate (1991-2020) and future climate (202...

The correlation between the occurrence of four enniatins (ENA, ENA1, ENB, and ENB1) and beauvericin (BEA) and the weather parameters during anthesis and preharvest period was studied in 97 wheat samples collected in 2014 and 2015 across three counties from central and south Romania (Braşov, Dâmboviţa, and Teleorman). The highest mean values of ENA...

Ground-based meteorological observations are used here as proxy data, as well as aerosol reanalysis estimates for training, to reconstruct aerosol optical depth (AOD) time series over Romania during a multidecadal period (1961–2015). The approach uses sunshine duration fraction (SDF) data computed for cloudless summer days (identified from 6-hourly...

Bucharest is one of the European cities most at risk of being affected by meteorological hazards. Heat or cold waves, extreme temperature events, heavy rains or prolonged precipitation deficits are all-season phenomena, triggering damages, discomfort or even casualties. Temperature hazards may occur annually and challenge equally the public, local...

Bucharest is one of the European cities most at risk of being affected by meteorological hazards. Heat or cold waves, extreme temperature events, heavy rains or prolonged precipitation deficits are all-season phenomena, triggering damages, discomfort or even casualties. Temperature hazards may occur annually and challenge equally the public, local...

Bucharest is one of the European cities most at risk of being affected by meteorological hazards. Heat or cold waves, extreme temperature events, heavy rains or prolonged precipitation deficits are all-season phenomena, triggering damages, discomfort or even casualties. Temperature hazards may occur annually and challenge equally the public, local...

Past and projected variability of the air temperature, precipitation, evapotranspiration and aridity in the South-Eastern Europe are evaluated throughout 1961–2050. Changes in aridity are estimated by means of five indices: de Martonne Aridity Index, UNEP Aridity Index, Pinna Combinative Index, Johansson Continentality Index and Kerner Oceanity Ind...

The impact of climate on crop evapotranspiration (ETc) was assessed in the Pannonian basin for the present (1991–2020) and future (2021–2050). Annual temperature, annual precipitation and monthly potential evapotranspiration are the main climate data used in the present study. The European land cover database was used for the spatial recognition of...

Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and seasonal R-factor maps and assess rainfall erosivity...

Two products provided by the climate monitoring satellite application facility (CMSAF) are the instantaneous Cloud Fractional Coverage (iCFC) and the instantaneous Cloud Type (iCTY) products. Previous studies based on the iCFC product show that the simple solar radiation models belonging to the cloudiness index class n CFC = 0.1–1.0 have rRMSE valu...

Extreme hot events and heat waves occur frequently in Bucharest during the warm season, triggering significant heat stress and thermal risks, especially in buildings with inappropriate ventilation, while climate change scenarios agree upon the warming trend along the next decades. This study investigates the impact of the Urban Heat Island (UHI) on...

Assessment of risk considering both the probability of occurrence of a natural phenomenon and its consequences on the elements at risk is an essential step before the design of adequate risk reduction strategies in local, regional or national level. Within the EU-funded project SEERISK ‘‘Joint disaster management risk assessment and preparedness fo...

As a follow up and an advancement of the recently published Rainfall Erosivity Database at European Scale (REDES) and the respective mean annual R-factor map, the monthly aspect of rainfall erosivity has been added to REDES. Rainfall erosivity is crucial to be considered at a monthly resolution, for the optimization of land management (seasonal var...

A two-step interpolation framework is proposed for the first time for computing sub-daily (6-hour) precipitation maps over Romania, over 36 years (1975-2010), using meteorological and ancillary data. In the first step, the monthly climatology maps were constructed. Here, the auxiliary predictors were quantified with the help of multi-variate geosta...

The relationship between the clearness index and the time averaged sunshine number is studied over short time intervals such as one hour. Several non-linear statistical models have been used. Meteorological and radiometric data from various weather stations of Romania (South-Eastern Europe) are analyzed. Nonlinearity of the relationship is only app...

A statistical downscaling model to estimate a summer thermal stress index (THI, temperature-humidity index) at 87 stations (predictand) in Romania from large-scale predictors is presented in this study. The statistical downscaling model is based on canonical correlation analysis (CCA), is calibrated over the 1961-1990 interval and validated over th...

Changes in the characteristics of the variability for two indices quantifying the winter (WCT: wind chill equivalent temperature chart index) and summer (THI: temperature-humidity index) thermal stress at a high spatial resolution across Romania for the 1962-2010 period are analysed. The linear trends, shifts in the mean and main modes of variabili...

This chapter is organized in four sections, which refer to the homogenization algorithm applied to the meteorological data, the statistical methods, the spatialisation methods used to derive the climatological maps and the regional climate models used to derive the future changes in the climate of the Romanian Carpathians. The homogenization was do...

The chapter is organized in two sections. The first section overviews the main impulses, initiatives and achievements in global and European environmental research targeting mountain regions since the early 1970s until 2012 (the Rio +20 Conference). This section also highlights how the growing significance of the climate change issue in global envi...

Several indices of climate extremes – based on minimum and maximum temperature, daily precipitation and daily snow cover – were used in order to check for changes over 1961–2010. The most important changes were found in maximum and (to a lesser extent) in minimum seasonal temperature. The warming signal is well retrieved in the trends in thermal-re...

This chapter briefly presents the changes of the air temperature and precipitation amounts predicted by Regional Climate Models for the next decades over the Romanian Carpathians. The analysis refers to the IPCC Scenario A1B, and exploits the outputs of several European projects developed in the recent years. The air temperature is likely to increa...

This chapter outlines the importance of three major factors and the effects of their joint action in defining local and regional climatic features of the Romanian Carpathians: latitude and longitude, topography and the regional atmospheric circulation. The chapter summarizes the role of latitude and longitude in shaping the distribution of the dire...

This chapter provides a description of the main climatic conditions of the Romanian Carpathians region based on the analysis of the regime of the most important climatic parameters such as air temperature, precipitation, wind and snow. The regional climatic patterns are discussed in terms of elevation effect, influence of the prevailing atmospheric...