Analysis of the 2014 Wet Extreme in Bulgaria: Anomalies of Temperature, Precipitation and Terrestrial Water Storage (original) (raw)
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Variability and trends of extreme precipitation events over Bulgaria (1961–2005)
Atmospheric Research, 2009
Heavy precipitation events often lead to river floods and flash floods causing significant loss of life and property damage, landslide activation, and other social and economic problems. The upward tendency of damages, caused by natural disasters, supports the idea that extreme events, associated with the effects of climate change, have recently occurred with greater frequency. The series of hazardous precipitation events which affected the Balkans and in particular Bulgaria in 2005 show that further study of such type of phenomena is necessary in order to improve their predictability. The subject of the present study is the variability and the trends associated with extreme precipitation events in Bulgaria during the period 1961-2005. Total precipitation amounts exceeding 30 mm/day which occur in 4 or more provinces of the country are considered to be risky for floods. We call them here heavy-rain days or events. The regime of such potentially dangerous heavy-rain/snow events is compared to those of total precipitation amounts for two periods: 1961-1990 and 1991-2005. Significant increase (more than 32%) of the days with heavy 24-hour precipitation is revealed during the second period, while the total annual rainfall is almost without changes or shows a slightly decreasing trend in many regions of the country. Besides, the contribution of heavy and torrential rain/snow to the observed annual precipitation totals increases. It is in contrast with the observed trend of decrease for the weak and moderate precipitation amounts. Two typical synoptic situations, leading to such type of extreme events in the extreme year 2005 are presented. The first is a "winter" one in February and the seconda "summer" one in July.
Statistical Analysis of Monthly Precipitation Sums in Bulgaria for the 1982-2010 Period
The aim of the paper is to reveal variations of monthly precipitation sums for the 1982-2010 period. Official meteorological data for few stations in Bulgaria are put under investigation. For achievement of the above-mentioned aim the statistical methods for analysis of temporal (dynamic) ranges are applied. An estimation of trend and season changes of development is made. Keywords: statistical analysis; temporal (dynamic) ranges; variations; trend of development; monthly precipitation sums 1. DATA The statistical records of 10 stations in Bulgaria, concerning monthly and annual precipitation sums for the 1982-2010 period are analyzed. For the first decade of this period (1982-1991) the data are gathered from official National statistical year-book. For the rest part of the period (1992-2010) data are gathered from national month's hydro-meteorological bulletins. There are missing data in 3 stations (Plovdiv, Ruse and Vratsa) for two years (1990 and 1991). Due to the lack of uni...
Drought Periods in Non-Mountainous Part of South Bulgaria on the Background of Climate Change
The present work aims to analyze drought periods in South Bulgaria in terms of its temporal variability, intensity, seasonal and territorial differences. The study areas are one of the main agricultural areas in Bulgaria and because of this investigation of drought in this region is very important. Drought periods are investigated on the base of seasonal precipitation totals and precipitation indices. The data for monthly precipitation from nine meteorological stations situated at the regions with different geographical conditions are used. The deviations of the seasonal and annual precipitation from normal (precipitation for the period 1961-1990) are used to determine drought periods in investigated stations. The duration of drought event is determined by Cumulative Precipitation Anomalies (CA). The Standardized Precipitation Indices (SPI) are calculated in order to determine moisture conditions and occurrence of drought periods in the investigated stations.
International Multidisciplinary Scientific GeoConference SGEM .., 2021
In order to assess the rainfall erosivity in the Pannonian basin, several parameters which describe distribution, concentration and variability of precipitation were used, as well as 9 extreme precipitation indices. The precipitation data is obtained from the European Climate Assessment and Dataset project for the period 1961-2014, for 8 meteorological stations in northern Serbia, 5 in Hungary and 1 in eastern Croatia. The extreme values of precipitation were calculated following the indices developed by the ETCCDI. RclimDex software package was used for indices calculation. Based on statistical analysis and the calculated values, the results have been presented with Geographic Information System (GIS) to point out the most vulnerable parts of the Pannonian basin, with regard to pluvial erosion. This study presents the first result of combined rainfall erosivity and extreme precipitation indices for the investigated area. Results of PCI indicate presence of moderate precipitation concentration (mean value 11.6). Trend analysis of FI (mean value 22.7) and MFI (mean value 70.2) implies a shift from being largely in the low erosivity class, to being completely in the moderate erosivity class in the future, thus indicating an increase in rainfall erosivity for most of the investigated area (except in the northwestern parts). Furthermore, the observed precipitation extremes suggest that both the amount and the intensity of precipitation are increasing. The knowledge about the areas affected by strong soil erosion could lead to introducing effective measures in order to reduce it. Long term analysis of rainfall erosivity is a significant step concerning flood prevention, hazard mitigation, ecosystem services, land use change and agricultural production.
Thermal Science, 2015
The aim of the present research work is to bring to better understanding the recent climate change at regional scale. The tendencies of many-years variability of air temperature and precipitation in Northeastern Bulgaria are determined. In order to determine future tendencies in air temperature and precipitation variability the data from regional climate models are analyzed. The occurrence of extreme monthly temperature and precipitation totals are investigated by calculation of 10 th and 90 th percentiles of the empirical distribution in the reference period . The main result of present work is that there are a positive tendency in changes of air temperature and negative in precipitation. The regional climate model data show increasing of extreme hot and dry months which is considerable for the second part of 21 th century.
THE EXTREMELY RAINY 2014 IN BULGARIA
In 2014 almost all stations of Bulgaria reported annual rainfalls significantly exceeding the norm, especially as far as the warm semester quantities are concerned. In this paper, the situation in the lowlands, plains, hilly areas and mountainous valley is presented. In eight of the 16 stations studied, the annual rainfalls exceeded 1000 mm, when the norm for most stations in the non-mountainous part of the country (lower than 600 m of elevation) was between 500 and 700 mm. Excess above annual norms varied between 177 and 578 mm with average values of about 350-450 mm. First and foremost this was due to a precipitation increase in the warm half of the year. An analysis of typical meteorological situations was made in order to clarify the causes for this anomaly. The number of Icelandic cyclones associated with rainfall situations over the country was slightly smaller than the usual one. The Mediterranean cyclones activity in the warm half of the year marked an untypical upward trend, most likely due to NAO index short time shifting from a positive to a negative phase. It can be suggested that this was the main reason for the substantial growth of rainfalls in Bulgaria during the warm season of 2014.
Meteorological drought in southwest Bulgaria during the period 1961-2020
Zbornik Radova: Geografski institut Jovan Cvijić, 2022
Although drought is a common phenomenon in Southern Europe, including Bulgaria, it can have adverse effects on human life and economic activities (water scarcity, reduced agricultural production, and economic losses to agriculture). This event occurs regionally, but it can spread over large areas. Whether it will be perceived as a hazard depends on the affected areas and the degree of impact. The article aims to provide new insight into the meteorological drought in the most densely populated NUTS 2 region of Bulgaria-the Yugozapaden (Southwestern). Based on Standardized Precipitation Indices (SPI-1 and SPI-3), its occurrence during the period 1961-2020 was analysed in terms of duration, intensity, and magnitude. The maximum drought duration and average drought intensity were determined using SPI-1. The seasonal distribution of drought shows its higher frequency in spring and summer, but on the other side, extreme drought was more common in winter and autumn. The maximum drought duration was observed mainly in the 1990s.
Changes in precipitation (P), evapotranspiration (ET) and, implicitly, in the climatic water balance (CWB), are imminent effects of climate warming. However, changes in the CWB, as a response to changes in P and ET, have not yet been analysed thoroughly enough in many parts of the world, including Romania. The present study explores the spatio-temporal changes of the CWB (difference between P and reference evapotranspiration, ET o) in Romania, based on a wide range of climatic data (P, as well as temperature, relative air humidity, sunshine duration and wind speed, necessary for computing ET o with the FAO-56 Penman-Monteith method) recorded at 70 weather stations across the country in the 1961–2013 period. As a secondary objective, the study attempts to identify the possible connections between the index's trends and large-scale atmospheric circulation, assessed based on the dynamics of certain European-scale relevant teleconnection indices. Thus, the Mann–Kendall test and Sen's slope methods were used to analyse CWB trends (but also P and ET o trends, in order to explain CWB pattern changes) annually, seasonally and in the maize and wheat growing seasons. Also, the Spearman correlation procedure and a composite analysis between interannual series of teleconnection indices and CWB were used to assess the influence of atmospheric circulation on the index's variability for all analysed time scales. The results generally showed CWB decreases (for the most part of up to −2 mm/yr, yet with a relatively low statistical significance) and highlighted an overall amplification of drier conditions on all time scales, except for autumn (CWB increases, generally of up to 1 mm/yr, but with low statistical significance). Moreover, net changes of even under −200 mm/53 yrs annually and −175 mm/53 yrs in summer and for the maize and wheat growing seasons were found in the CWB. Spatially, it was found that the country's southwestern and southeastern regions are the main epicentres of drier trends, while the northwest appears to have become wetter. Overall, the negative CWB trends are due to partial P decreases (statistically insignificant) and general ET o increases (highly statistically significant, even 100% in summer). It seems that the amplification of the climatic water deficit across the country is especially linked to the positive phases of the Arctic Oscillation and North Atlantic Oscillation, but also, in part, to those of several other teleconnection indices that affect Europe. Our results signal the necessity to adapt anthropic and ecological systems to future dryness trends countrywide, which will most likely intensify against the background of climate change expected to occur by the end of the century.
Recent trends in daily rainfall extremes over Montenegro (1951–2010)
Natural Hazards and Earth System Sciences Discussions, 2015
More intense rainfall may cause a range of negative impacts upon society and the environment. In this study we analyzed trends in extreme ETCCDI (Expert Team on Climate Change Detection and Indices) rainfall indices in Montenegro for the period 1951–2010. Montenegro has been poorly studied in terms of rainfall extremes, yet it contains the wettest Mediterranean region known as Krivošije. Several indices of precipitation extremes were assessed including the number of dry days and rainfall totals, and their trends to identify possible changes. The results generally suggest that the number of days with precipitation decreased while rainfall intensity increased particularly in south-western parts of the country. A slight tendency towards intense rainfall events is suggested. Calculated trends for each index are spatially presented and examined using a <i>plotGoogleMaps</i> software package. This study also examined spatial pattern of relationship between extreme rainfall ind...