Response of water temperatures and stratification to changing climate in three lakes with different morphometry

TitleResponse of water temperatures and stratification to changing climate in three lakes with different morphometry
Publication TypeJournal Article
Year of Publication2017
AuthorsMagee, Madeline R., and Wu Chin H.
JournalHydrology and Earth System Sciences
Pagination6253 - 6274
Date PublishedDec-11-2017
Keywordsclimate, lakes, stratification, water temperature

Water temperatures and stratification are impor- tant drivers for ecological and water quality processes within lake systems, and changes in these with increases in air temperature and changes to wind speeds may have signifi- cant ecological consequences. To properly manage these sys- tems under changing climate, it is important to understand the effects of increasing air temperatures and wind speed changes in lakes of different depths and surface areas. In this study, we simulate three lakes that vary in depth and sur- face area to elucidate the effects of the observed increasing air temperatures and decreasing wind speeds on lake thermal variables (water temperature, stratification dates, strength of stratification, and surface heat fluxes) over a century (1911– 2014). For all three lakes, simulations showed that epilim- netic temperatures increased, hypolimnetic temperatures de- creased, the length of the stratified season increased due to earlier stratification onset and later fall overturn, stability in- creased, and longwave and sensible heat fluxes at the sur- face increased. Overall, lake depth influences the presence of stratification, Schmidt stability, and differences in surface heat flux, while lake surface area influences differences in hypolimnion temperature, hypolimnetic heating, variability of Schmidt stability, and stratification onset and fall overturn dates. Larger surface area lakes have greater wind mixing due to increased surface momentum. Climate perturbations indi- cate that our larger study lakes have more variability in tem- perature and stratification variables than the smaller lakes, and this variability increases with larger wind speeds. For all study lakes, Pearson correlations and climate perturbation scenarios indicate that wind speed has a large effect on tem- perature and stratification variables, sometimes greater than

changes in air temperature, and wind can act to either amplify or mitigate the effect of warmer air temperatures on lake ther- mal structure depending on the direction of local wind speed changes. 

Short TitleHydrol. Earth Syst. Sci.