Trends and abrupt changes in 104 years of ice cover and water temperature in a dimictic lake in response to air temperature, wind speed, and water clarity drivers

Abstract

Abstract. The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate ice cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911-2014). The model results were then used to examine the drivers of changes in ice cover and water temperature, focusing on the responses to shifts in air temperature, wind speed, and water clarity at multiyear timescales. Observations of the drivers include a change in the trend of warming air temperatures from 0.081 • C per decade before 1981 to 0.334 • C per decade thereafter, as well as a shift in mean wind speed from 4.44 m s −1 before 1994 to 3.74 m s −1 thereafter. Observations show that Lake Mendota has experienced significant changes in ice cover: later ice-on date(9.0 days later per century), earlier ice-off date (12.3 days per century), decreasing ice cover duration (21.3 days per century), while model simulations indicate a change in maximum ice thickness (12.7 cm decrease per century). Model simulations also show changes in the lake thermal regime of earlier stratification onset (12.3 days per century), later fall turnover (14.6 days per century), longer stratification duration (26.8 days per century), and decreasing summer hypolimnetic temperatures (−1.4 • C per century). Correlation analysis of lake variables and driving variables revealed ice cover variables, stratification onset, epilimnetic temperature, and hypolimnetic temperature were most closely correlated with air temperature, whereas freeze-over water temperature, hypolimnetic heating, and fall turnover date were more closely correlated with wind speed. Each lake variable (i.e., ice-on and ice-off dates, ice cover duration, maximum ice thickness, freeze-over water temperature, stratification onset, fall turnover date, stratification duration, epilimnion temperature, hypolimnion temperature, and hypolimnetic heating) was averaged for the three periods (1911-1980, 1981-1993, and 1994-2014) delineated by abrupt changes in air temperature and wind speed. Average summer hypolimnetic temperature and fall turnover date exhibit significant differences between the third period and the first two periods. Changes in ice cover (ice-on and iceoff dates, ice cover duration, and maximum ice thickness) exhibit an abrupt change after 1994, which was related in part to the warm El Niño winter of 1997-1998. Under-ice water temperature, freeze-over water temperature, hypolimnetic temperature, fall turnover date, and stratification duration demonstrate a significant difference in the third period , when air temperature was warmest and wind speeds decreased rather abruptly. The trends in ice cover and water temperature demonstrate responses to both long-term and abrupt changes in meteorological conditions that can be complemented with numerical modeling to better understand how these variables will respond in a future climate.Published by Copernicus Publications on behalf of the European Geosciences Union.

Long-term changes in the hydrological regime of high mountain Lake Morskie Oko (Tatra Mountains, Central Europe)

“…Changes in the remaining elements of the hydrological regime of Morskie Oko are in accordance with the majority of studies on lakes in various parts of the world, both in reference to thermal conditions (Adrian et al, 2009;Coats et al, 2006;Hampton et al, 2008) and the course of ice phenomena (Benson et al, 2012;Futter, 2003;Korhonen, 2006;Magee et al, 2016). The scale of transformations depends on the location and local conditions of particular lakes.…”

Variability and course of occurrence of ice cover on selected lakes of the Gnieźnieńskie Lakeland (Central Poland) in the period 1976–2015

“…In the case of Lake Lunz (Austria), Kainz et al [12] observed a reduction of duration of ice cover, and the average rate of the phenomenon amounted to 1.85 day·dec -1 . In research on Lake Mendota (USA), Magee et al [13] found that the development of ice cover occurred 9 days per century later, and its disintegration occurred 12.3 days per century earlier, resulting in a decrease in duration of ice cover (by 21.3 days per century). In research on 75 lakes on the Northern Hemisphere, Benson et al [14] determined later freezing of lakes (0.3-1.6 day·dec -1 ), earlier disappearance of ice (0.5-1.9 day·dec -1 ), and its shorter duration (0.7-4.3 day·dec -1 ).…”

Effect of Teleconnection Patterns on Changes in Water Temperature in Polish Lakes

“…This refers to water level fluctuations [1], ice phenomena [2], as well as water temperature [3]. In addition to the research trend concerning the assessment of long-term tendencies of changes in the hydrosphere in the times of global warming, numerous studies refer to the effect of types of macroscale circulation of the atmosphere on its different components.…”