GROWING-SEASON TEMPERATURES OVER THE FORMER SOVIET-UNION

Analyses of daily mean temperatures during the growing season (days > 5 degrees C) from about 200 stations over the former Soviet Union indicate that little change has taken place in a number of growing-season-related variables during the last 110 years. We have considered the start (STR), end (END), duration (DUR), and the number of degree-days above 5 degrees C (DD). Annual average temperatures in the region have warmed by about 1 degrees C, but this increase has been confined to the October-to-April period. Time series of the variables at individual stations show that there is little correlation between the start and end dates of the growing season and between the duration and the number of degree-days in the season. Mean May-to-September temperatures at individual stations are shown to be highly correlated with the number of degree-days, implying that the average of an appropriate combination of monthly temperatures can be used as a proxy for the number of degree-days when daily data are not available. The low correlation between degree-day counts and growing season duration in time series at all the stations is surprising given the strong spatial dependence between the 1950-1989 averages of the variables at all the stations. The results have implications for studies concerned with the impacts on growing season temperatures of future climate change.