ANNUAL AND SEASONAL PRECIPITATION TRENDS WITHIN OLTENIA PLAIN, ROMANIA (1961-2010)

Abstract

 The present study aims at rendering the changes in annual and seasonal precipitation amounts,
during the period 1961–2010 within Oltenia Plain, as precipitation trend analysis, on different spatial and
temporal scales, has been considered of high interest in the context of global climate change. This dataset
includes 6 complete and homogeneous monthly precipitation time series from the analysed region. There
were calculated the annual and seasonal precipitation trends, which highlighted a certain spatial and temporal variability even if the analysed region covers a small surface. The observed changes on variability were estimated using linear regression techniques. Nevertheless, a decrease in annual precipitation has been registered within the entire plain during the middle decades of the analysed period. On an annual scale, precipitation has diminished or remained stationary over about than 85% of the study area;  however, the northern part of the plain displays a positive trend. The seasonal distribution is much complicated than the annual one, as different areas of the territory were affected by diminishing precipitation at a seasonal level, while others by increasing precipitation. Thus, winter and spring amounts decreased all over the plain except for the northern part, where the trend is almost linear in winter and slightly upward in spring. Summer precipitation indicates linear trends, except for the northern and southwestern parts where the trend is upward. The data analysis emphasizes that the season undergoing the most obvious increase in total amounts is autumn, all over the plain, except for the western part, where it represents the season with the most obvious downward trend.