Model validation and drought assessment with a regional climate model over Moldova

10.7160/sab.2012.430403We assess the drought characteristics in the Republic of Moldova based on the Standardized Precipitation Index (SPI) calculated from monthly precipitation data simulated by the Regional Climate Model RegCM3. The RegCM simulations were conducted at a horizontal resolution of 10 km in the framework of EU-FP6 project Central and Eastern Europe Climate Change Impact and Vulnerability Assessment (CECILIA). The domain was centered over Romania at 46ºN, 25ºE and included the Republic of Moldova. We validate the model ability to simulate monthly temperature and precipitation by comparing the model simulations forced by ERA40 with the observations from CRU TS2.0 dataset and station observations for the period 1961¿1990. The RegCM simulations (control and scenario runs) forced with the ECHAM5 Global Circulation Model (GCM) have been corrected against the systematic errors induced by the GCM. After the bias correction, the annual cycle of temperature and precipitation is analyzed by comparing the model simulations conducted under A1B scenario for the periods 2021¿2050 and 2071¿2100 with the control run for the period 1961¿1990.The characteristics of the drought for the current climate were assessed based on SPI calculated for 1¿24 month lags from CRU dataset and station observations. The SPI for 1, 3, 6, 12, 18, and 24-month lag was calculated and analyzed for RegCM simulations. The results show that the model underestimates the severity of droughts

Observed spatiotemporal characteristics of drought on various time scales over the Czech Republic

10.1007/s00704-013-0908-yThis 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 t

Spatial and temporal evolution of drought conditions at various time scales in the Czech Republic during growing period

This paper analyzes the characteristics of spatial evolution of the standardized precipitation evapotranspiration index (SPEI) at various time scales during the growing period (April-September) over the Czech Republic. The SPEI was calculated from monthly records of mean temperature and precipitation totals measured at a dense network of 184 climatological stations for the period 1961-2010. Using various lags, 1, 3, 6, 12, and 24 months. The drought at these time scales is relevant for agricultural, hydrological, and socio-economic impacts, respectively. The study refers to the warm season of the year (from April to September). The principal modes of variability of the SPEI calculated at these five time scales were identified by using the empirical orthogonal functions (EOF) analysis. The explained variance of the leading EOF ranges between 71 and 61% as the time scale for calculating the SPEI increases from 1 to 24 months. The explained variance of EOF2 and EOF3 ranges between 5 and 9%, and 4 and 6%, respectively, as the SPEI is calculated for 1-24 months. With a few exceptions at stations at the highest altitudes, the spatial coefficients of the EOF1 for all SPEI time scales have the same sign over the country's territory. Based on the spatial distribution of the spatial coefficients of EOF2 and EOF3, at all SPEI time scales we have identified three climatically homogenous regions, corresponding to the altitudes below 400 m, between 401 and 700 m, and above 700 m. This regionalization corresponds to some extend to that which was previously used in other studies. These three regions reflect different land use types corresponding to: (i) mostly intensive agriculture, (ii) less intensive agriculture, and (iii) limited agricultural production and mostly forested, respect

Problems of dating human bones from the Iron Gates

It is widely recognised that when marine resources form a significant proportion of the human diet, this results in radiocarbon ages for human remains that are significantly older than the contemporary atmosphere. While there has been widespread assessment of marine <sup>14</sup>C reservoir ages, there has been litle study of the freshwater equivalent. However, recent analyses of human bone from archaeological sites in the Danube Valley have confirmed the existence of a large freshwater <sup>14</sup>C reservoir effect

Observational evidence for soil-moisture impact on hot extremes in southeastern Europe

Climate change is expected to affect not only the means of climatic variables, but also their variabilities1,2 and extremes such as heat waves2–6. In particular, modelling studies have postulated a possible impact of soil-moisture deficit and drought on hot extremes7–11. Such effects could be responsible for impending changes in the occurrence of heat waves in Europe7. Here we analyse observational indices based on measurements at 275 meteorological stations in central and southeastern Europe, and on publicly available gridded observations12. We find a relationship between soil-moisture deficit, as expressed by the standardized precipitation index13, and summer hot extremes in southeastern Europe. This relationship is stronger for the high end of the distribution of temperature extremes. We compare our results with simulations of current climate models and find that the models correctly represent the soil-moisture impacts on temperature extremes in southeastern Europe, but overestimate them in central Europe. Given the memory associated with soil moisture storage, our findings may help with climate-changeadaptation measures, such as early-warning and prediction tools for extreme heat wave

Data from: Dogs accompanied humans during the Neolithic expansion into Europe

Near Eastern Neolithic farmers introduced several species of domestic plants and animals as they dispersed into Europe. Dogs were the only domestic species present in both Europe and the Near East prior to the Neolithic. Here, we assessed whether early Near Eastern dogs possessed a unique mitochondrial lineage that differentiated them from Mesolithic European populations. We then analysed mitochondrial DNA sequences from 99 ancient European and Near-Eastern dogs spanning the Upper Palaeolithic to the Bronze Age to assess if incoming farmers brought Near Eastern dogs with them, or instead primarily adopted indigenous European dogs after they arrived. Our results show that European pre-Neolithic dogs all possessed the mitochondrial haplogroup C, and that the Neolithic and Post-Neolithic dogs associated with farmers from Southeastern Europe mainly possessed haplogroup D. Thus, the appearance of haplogroup D most likely resulted from the dissemination of dogs from the Near East into Europe. In Western and Northern Europe, the turnover is incomplete and C haplogroup persists well into the Chalcolithic at least. These results suggest that dogs were an integral component of the Neolithic farming package and a mitochondrial lineage associated with the Near East was introduced into Europe alongside pigs, cows, sheep, and goats. It got diluted into the native dog population when reaching the Western and Northern margins of Europe