Seasonal trends in the Early Twentieth Century Warming (ETCW) in a centennial instrumental temperature record from Central Europe

Abstract

The goal of the present paper is to investigate whether any objectively defined and statistically significant changes can be discovered in one of the longest homogenized instrumental temperature records in East-Central Europe. Thus, it is hoped that the present analysis will add to earlier attempts and elucidate the persistence of the warming period observed in the early 20th century. Similar to the global tendency, the Early Twentieth Century Warming (hereinafter, ETCW) period can be identified between 1931 and 1951 in the annual mean temperature time series of Keszthely, a small town in Hungary. The Mann-Kendall trend test was used to determine whether a monotonic trend was present, as it is not possible to regard the residuals of the linear trend as normally distributed. A significant rising trend can be observed in the warming period in spring of the years between 1925 and 1951. In case of summer and autumn, this period cannot be characterized as having any significant identifiable trend. A rise in the mean can, however, be recognized. Overall, the specific regional manifestation of the global ETCW may clearly be illustrated in this study via detailed statistical analysis of the temperature records for Keszthely, a location with one of the longest temperature records in Hungary. However, other regions surrounding Hungary show similar climatic trends, emphasizing the fact that the behaviour presented here is not unique to Central and Eastern Europe.