Constanta Boroneant - Academia.edu (original) (raw)

Papers by Constanta Boroneant

DOAJ (DOAJ: Directory of Open Access Journals), Nov 1, 2013

Using visualization techniques to outline vulnerability to drought in the Republic of Moldova. Th... more Using visualization techniques to outline vulnerability to drought in the Republic of Moldova. This paper is a demonstration of use of various visualization techniques in representing the results on vulnerability to drought at various times scales in the Republic of Moldova. Monthly precipitation totals from simulated data at 10 km horizontal resolution with a regional climatic model RegCM, CRU TS2.10 land observation data set at 0.5ºx0.5º horizontal resolution and observations recorded at 15 meteorological stations in Moldova were used to compare the annual cycle of precipitation, seasonal variability of precipitation, and the spatial and temporal evolution of drought. The Empirical Orthogonal Functions (EOF) analysis was used to identify the principal modes of seasonal variability of precipitation over the country and the Standardized Precipitation Index (SPI) was calculated as an indicator of drought or wetness at various time scales (1 to 24 months). The period of analysis was 1960-1997. One of the visualization techniques was the Grid Analysis and Display System (GrADS) which is an easy manipulation and visualization tool for gridded and station meteorological data. We used it to represent the RegCM and CRU data on their grids. The kriging interpolation with a Gaussian model variance was selected as a suitable interpolation tool for the spatial distribution of the SPI and EOF over Moldova. For temporal diagram and mapping, Golden Software Surfer 9.0 and ArcGis Software 9.1 were used. The results presented with these visualization tools emphasize precipitation and drought characteristics over Moldova domain.

Quarterly Journal of the Royal Meteorological Society, Jan 15, 2001

The relationships between decadal (>5-year period) observed winter precipitation (PP) variability... more The relationships between decadal (>5-year period) observed winter precipitation (PP) variability over EUrope and atmospheric circulation and sea surface temperature (SST) during the period 1950-1995 are investigated. More than 48% of the decadal precipitation variability is described by two modes: a meridional dipolar pattern (high PP over northern Europe and low over southern Europe, the Mediterranean and most of central Europe) explaining about 32% of the variance, and an alternating pattern in latitude over Europe (high in central Europe and low in far northwestern Europe and the Mediterranean) explaining about 16% of the variance. The first mode is strongly related to the North Atlantic Oscillation. A canonical correlation analysis between regional precipitation and sea-level pressure fields shows that a PP pattern similar to the first decadal PP mode is associated with a north-westerly circulation anomaly pattern while a PP pattern similar to the second decadal PP mode is associated with a monopolar circulation anomaly pattern over most parts of Europe. The correlation map between the time series of expansion coefficients of the first PP mode and sea surface temperature emphasizes a global pattern which resembles the linear trend coefficients pattern of SST for the analysed period. The second PP mode is associated with an SST anomaly pattern similar to that of the SST anomalies characterizing 'decadal El Niiio Southern Oscillation' SST pattern. Composite maps of global 500 mb geopotential height based on the time series of expansion coefficients of PP modes emphasize global patterns compatible with SST patterns. After removing the linear trend from the data, the first PP pattern remains almost unchanged but it emphasizes mainly regional connections. The second spatial pattern of the second PP mode and its connections are not affected significantly by removing the trend.

The Romanian Plain, covering a surface area of about 52 600 sq.km and stretching along the Danube... more The Romanian Plain, covering a surface area of about 52 600 sq.km and stretching along the Danube, is one of the largest agricultural regions in the European Union. It presents diverse ecological conditions in four major zonal units, steppe, silvo-steppe, forest zone and its large Danube floodplain. In this context, the assessments of climate change, specifically of those climatic elements like temperature and precipitation which may have an important impact on various economic sectors, represent a necessary scientific support for end-users to envisage sustainable development strategies. This paper presents 1) the evaluation of the regional climatic model RCA4 driven by the ERA-Interim reanalysis and five general climatic models under historical forcing, 2) the adjustment of the bias identified in the simulations compared to the observation data using the Delta Change method, and 3) the projected changes of seasonal mean temperature and precipitation in the Romanian Plain for the mi...

Drought is a climatic extreme event causing environmental damages that limit plant development an... more Drought is a climatic extreme event causing environmental damages that limit plant development and crop yields, with significant economic and societal impacts. Mitigation and adaptation measures to drought are the responsibility of both farmers and government entities requiring integrative management plans and strategies which account for the local particularities. The paper presents an assessment of socioeconomic effects of drought in the Turnu Măgurele – Giurgiu sector of the Romanian Danube Valley (RDV) based on a comprehensive analysis of specific climatic and socioeconomic indicators. Drought was quantified by the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) at 1to 24-month lags at three representative stations in the area, during the 1961–2017 period. The analysis shows that among the consequences of severe drought events that affected the study-area during the last decades were the yield losses and increasing prices...

International Journal of Climatology, 2002

The decadal variability (>5 years) of the Danube river flow in the lower basin and its connection... more The decadal variability (>5 years) of the Danube river flow in the lower basin and its connection with the North Atlantic Oscillation (NAO) is analysed for the period 1931-95. Associated linkages with precipitation (PP) in the European sector, global sea surface temperature (SST) and atmospheric circulation for the period 1931-81, and the 500 hPa geopotential heights (G500) over the Northern Hemisphere for the period 1948-95 are also investigated. The results show that there is an out-of-phase relationship between the time series of the Danube river flow anomalies and the NAO index. The time series of a PP index, defined as the average of normalized precipitation anomalies over a large area including the Danube basin, presents a time evolution similar to that of the river flow anomalies. The correlation maps between the river flow anomalies and global SST show coherent large-scale patterns. High values of the Danube river flow are associated with a tripole-like SST structure in the North Atlantic similar to that appearing during the negative phase of the NAO, and with negative SST anomalies in the central North Pacific and positive SST anomalies in the eastern and central tropical Pacific. Physically consistent sea level pressure and 500 hPa geopotential height are obtained.

CLIVAR-SPAIN contributions: Seasonal drought variability over the Iberian Peninsula and its relat... more CLIVAR-SPAIN contributions: Seasonal drought variability over the Iberian Peninsula and its relationship to global sea surface temperature and large scale atmospheric circulation

Theoretical and Applied Climatology, 2006

Extreme precipitation over the Maritime Alps and associated ... C. Boroneant 1 , G. Plaut 2 , F. ... more Extreme precipitation over the Maritime Alps and associated ... C. Boroneant 1 , G. Plaut 2 , F. Giorgi 3 , and X. Bi 3 ... Received December 17, 2004; revised May 24, 2005; accepted September 1, 2005 Published online July 25, 2006 # Springer-Verlag 2006 ... We use the regional ...

EGU General Assembly Conference Abstracts, Apr 1, 2019

A comparison between two empirical methods for calculating potential evapotranspiration (PET), na... more A comparison between two empirical methods for calculating potential evapotranspiration (PET), namely Hargreaves and Penman-Monteith is presented using the downscaled time series from CRU TS3.21 observation dataset at the closest grid point to Chisinau station coordinates, and observation series at Chisinau climatological station in the Republic of Moldova for the period 1951-2012. The Hargreaves PET model is based on minimum and maximum air temperature and extra-terrestrial radiation, while the PenmanMonteith method is based on minimum, maximum and mean air temperature, vapour pressure and cloud cover. The following diagnostic statistical quantities are analysed: (1) correlation coefficient (r) and (2) coefficient of determination (R in %).

Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen, 2009

During the last decades global warming became a major environmental threat, gradually supported b... more During the last decades global warming became a major environmental threat, gradually supported by scientific data. Climate change effects induced by increased anthropogenic greenhouse gas production (IPCC 2007a) are evidenced, for example, by the ozone hole over the Antarctica (SOLOMON et al. 2007), ocean acidification due to increasing atmospheric carbon dioxide (IPCC 2007a), increased heat budgets in oceans and hence alterations of large-scale currents (BARNEIT et al. 2005), melting glaciers in all continents (WGMS 2005), and rising sea levels (IPCC 2007a). Presently, climate modelers are downscaling from global climate models to regional climate models and to lake and catchment models (http://clime.tkk.fi). This is important in view of changes in the hydrological water cycle and water resources affecting the residents in river basins. Obviously, changes in precipitation and increase in atmospheric temperature impact lakes and rivers (FOREMAN et al. 2001, WEYHENMEYER et al. 2004 ...

During the last decades a growing number of heat waves have been observed in Romania during summe... more During the last decades a growing number of heat waves have been observed in Romania during summer. The current index used in the National Meteorological Administration in Bucharest for quantifying human comfort is a temperature-humidity index (ITU). The heat warning is issued by the National Forecasting Center in two stages: warning stage 1 (alert stage) when the ITU value is between 66 and 79 units and, warning stage 2 (risk stage) when the ITU value is greater than 80 units. This paper presents the trends of the number of days with warnings (alert and risk, separately) at 15 stations located in the south and south - east of Romania's territory during summer for the period 1961-2007. Hourly data of air temperature and relative humidity for the interval 12-18 local time have been used for the study. The frequency of warnings during that hourly interval is assessed for each month (June, July and August) based on ITU thresholds. Finally, the spatial distribution of the warning fr...

Theoretical and Applied Climatology, 2013

ABSTRACT This paper analyses the observed spatiotemporal characteristics of drought in the Czech ... more ABSTRACT This paper analyses the observed spatiotemporal characteristics of drought in the Czech Republic during the growing season (April to September) as quantified using the Standardised Precipitation Evapotranspiration Index (SPEI) on various time scales. The SPEI was calculated for various lags (1, 3, 6, 12, and 24 months) from monthly records of mean temperature and precipitation totals using a dense network of 184 climatological stations for the period 1961–2010. The characteristics of drought were analysed in terms of the temporal evolution of the SPEI, the frequency distribution and duration of drought at the country level, and for three regions delimited by station altitude. The driest and the wettest years during the growing season were identified. The frequency distribution of the SPEI values for seven drought category classes (in per cent) indicates that normal moisture conditions represent approximately 65 % of the total SPEI values for all time scales in all three regions, whereas moderate drought and moderate wet conditions are almost equally distributed around 10.5 %. Differences in extremely dry conditions (5 %) compared with extremely wet conditions (1.5 %) were observed with increasing SPEI time scales. The results of the non-parametric Mann–Kendall trend test applied to the SPEI series indicate prevailing negative trends (drought) at the majority of the stations. The percentage of stations displaying a significant negative trend for the 90, 95, 99, and 99.9 % confidence levels is approximately 40 %. An Empirical Orthogonal Functions (EOF) analysis was used to identify the principal patterns of variability of the SPEI during the growing season that accounted for the highest amount of statistical variance. The variance explained by the leading EOF range 66 to 56 %, whereas for EOF2 and EOF3, the value is between 7 and 11 % and between 4 and 7 %, respectively, for the SPEI is calculated for 1- to 24-month lags.

International Journal of Climatology, 2004

The spatial and temporal variability of the river discharges and precipitation from the southern ... more The spatial and temporal variability of the river discharges and precipitation from the southern part of Romania for 69 years, during the period 1931-99, is investigated. The study is based on river discharges (precipitation) data recorded at ten hydrometric and six meteorological stations from this region. The cross-correlation analysis reveals a seasonal dependence of the lag time between the precipitation and river discharge anomalies, being larger (2-3 months) in winter than in summer (0-1 month). The correlation and the EOF analyses reveal consistent interannual to decadal variations for precipitation and river discharges. In particular, persistent meteorological and hydrological droughts were identified during 1943-52, 1958-68 and 1980-99. A composite analysis reveals that high (low) values of the river discharge and precipitation in this region are related to a large-scale atmospheric circulation pattern similar to the negative (positive) phase of the North Atlantic oscillation (NAO). This suggests that, during periods of persistent positive phase of NAO, persistent meteorological and hydrological drought conditions are expected in the southern part of Romania with important consequences on the climate and economy of this region.

Climate of the Past, 2007

Temperature data recorded in 2002 and 2003 at 10 stations out of the 70 of the Romanian automatic... more Temperature data recorded in 2002 and 2003 at 10 stations out of the 70 of the Romanian automatic weather stations network are presented and analyzed in terms of the heat transfer from air to underground. The air temperature at 2 m, the soil temperatures at 0, 5, 10, 20, 50 and 100 cm below soil surface as well as precipitation and snow thickness have been monitored. The selected locations sample various climate environments in Romania. First order modelling confirm that at certain locations and for certain time intervals soil temperatures track air temperature variations and consequently the heat transfer is by conduction, while at others, processes such as soil freezing and/or solar radiation heating play an important part in the heat flux balance at the air/soil interface. However, the propagation of the annual thermal signal in the first meter of soil is through conduction; the effective thermal diffusivity for 8 stations with continuous time series at all depth levels ranges from 3 to 10×10 −6 m 2 s −1 .

Este trabajo analiza la relación entre las condiciones estaciónales extremadamente secas y húmeda... more Este trabajo analiza la relación entre las condiciones estaciónales extremadamente secas y húmedas en la República Checa y los patrones de circulación de gran escala. El índice estandarizado de precipitación y evapotranspiración (SPEI) se utiliza para cuantificar las condiciones de humedad. El SPEI fue calculado a partir de los registros mensuales de temperatura media y precipitación total de una densa red de 184 estaciones climatológicas para el período 1961-2010 en la escala temporal de un mes. Fueron identificados los principales modos de variabilidad estacional del SPEI utilizando el análisis de funciones empíricas ortogonales (EOF). El porcentaje de varianza explicada de los tres primeros EOF varía entre 58% y 66% dependiendo de la estación. Se hicieron mapas compuestos de la presión media al nivel del mar (MSLP), del contenido de vapor de agua (WPC) y de la temperatura superficial del mar (SST) sobre la base de la serie PC1 del SPEI estacional en la escala de un mes, para los años en que el valor fue mayor o menor que 0.75 desviaciones estándar de la serie. Los patrones de gran escala para el MSLP, WPC y SST ofrecen una visión sobre los principales factores que conducen a condiciones extremas, secas y húmedas, en la República Checa a escala estacional. Palabras clave: Índice estandarizado de precipitación y evapotranspiración, condiciones secas y húmedas, funciones empíricas ortogonales, República Checa.