CR 42:247-256 (2010)  -  DOI: https://doi.org/10.3354/cr00922

ABSTRACT: A trend analysis of surface temperature in Chisinau (Moldova) between 1887 and 2008 is presented. The observational data included monthly mean temperatures (Tmean) for the whole period, and monthly mean maximum (Tmax) and minimum (Tmin) temperatures since 1945. The following principal aspects were studied: (1) long-term temperature trends and changes in their patterns; (2) seasonal temperature extremes and their links with rising mean temperatures; and (3) an extremely hot summer of 2007 in Moldova as evidence of regional warming. In the last 3 decades, strong positive trends were observed in all temperature variables and, unlike previous periods (1945–1980), have become statistically significant for most seasons. Trends increased drastically: annual, winter and summer Tmean rose by about 0.62, 0.50 and 0.95°C per decade, respectively, in 1981–2008, compared with 0.035, 0.075 and 0.018°C per decade, respectively, in 1887–1980. Means of seasonal (except autumn) and annual temperatures in 1981–2008 differed from previous years at a 95% and higher confidence level; their variability, expressed in standard deviation (SD) values (σ), did not change significantly. In the last 3 decades there was practically no significant change in means, variability and distribution of Tmax in comparison with 1945–1980; however, Tmin changed significantly in all these statistics. The lack of significant changes in recent Tmax resulted in a relative stability of the frequency of temperature extremes, defined as the 90th and 95th percentiles of long-term distributions in winter and summer; some increase is observed only for absolute maxima. In 1981–2008 these thresholds for mean Tmin were exceeded 7 and 3 times, respectively, compared to the 1940s–1970s, when there were no such extreme events. The results strongly suggest that the observed warming in Chisinau was primarily caused by the Tmin increase. In summer 2007, monthly Tmean exceeded the corresponding values of the baseline (1961–1990) climate by 2.5–4.0 σ, the seasonal Tmean by 5 σ.

KEY WORDS: Climate change · Air temperature trends · Extremes · Moldova