Changes in ice phenology characteristics of two Central European steppe lakes from 1926 to 2012 - influences of local weather and large scale oscillation patterns

Ice cover of the two Central European steppe lakes, Lake Balaton (Hungary) and Lake Neusiedl (Austria/Hungary), is characterized by high interannual variability (mean ice duration ± s.d.: 44 ± 26 days and 73 ± 28 days, respectively). For both lakes, a trend towards shorter ice duration and earlier ice-off can be observed in the 86 and 81 year data records, respectively. For Lake Neusiedl, significant trends for ice-on (+2.3 days decade −1), ice-off ( −1.8 days decade −1) and ice duration ( −3.1 day decade −1) are detected. At Lake Balaton, however, trends for ice-on (0 day decade −1), ice-off ( −0.7 days decade −1) and ice duration ( −1.2 days decade −1) are not significant. The temporal trends have accelerated for Lake Neusiedl in the past 60 years (ice duration −5.6 days decade −1). The variability of the ice parameters has increased during the 80 year observation period for Lake Neusiedl, but not for Lake Balaton. The number of melt-refreeze cycles at Lake Balaton increased at first, but then decreased during the last 20 years at both lakes.