Changes observed in the climatic regime in Romania

Researches performed by the climatologists of the National Meteorological Administration, o­n the basis of long data series from 14 weather stations have highlighted a mean all-country warming of 0.3ºC over the 1901-2000 interval and of 0.5ºC over the 1901-2007 interval, statistically significant in the extra-Carpathian area (fig. 1), with certain seasonal differentiations. An analysis based o­n data from a higher number of weather stations (94), with continuous observation series starting in 1961, disclosed an intensification of the warming phenomenon in the latest decades. Thus, in the 1961-2007 interval, a significant warming of about 2ºC was evident throughout the country in summer, and in winter and spring in the extra-Carpathian areas, with wider departures in Moldavia, in excess of 2ºC (in winter) and 1ºC (in spring), whereas during the autumn a slight cooling trend in remarkable all over the country, however- not statisticalally significant.

From the precipitation standpoint, a general decreasing trend, more marked in the centre of the country, with small increases in the north-east and in places in the south, has been apparent. After 1961, a trend towards excess in the south of the country is growing stronger with respect to the autumn precipitation amounts. An important characteristic of the temporal variability of precipitation amounts is the marked interdecadal component, which makes is difficult to separate the long-term climatic signal.

Fig. 1.Linear trends for the mean annual air temperature (ºC) over the 1901-2007 interval (a) and the annual precipitation amount (mm) in the 1891-2007 period (b).

 

 

Other changes observed in the regime of the climatic parameters in Romania over the 1961-2007 period:

 

-A decrease of the mean wind speed, both at annual level (in most of the country’s areas, and at seasonal level. The decreasing trend rate reaches different levels, function ofthe season and geographic position and is more enhanced in the eastern areas and in the mountains.

-An increase of the maximum duration of the intervals without precipitation in the south (in winter) and in the west (in summer);

-A significant increase of the number of days with precipitation greater than 10 mm/day (with up to 4 days), widely in the northern half of the country in the autumn season;

-A significant increase of the frequency of exceptional precipitation amounts, widely n the northern half, in the west and south-west of the country in autumn, with up to 3 days;

-A significant increase, in most of the country’s areas, of the annual frequency of the days with hoarfrost; the tendency of the last day with hoarfrost to move towards the spring.