Time scales of physical change in the lake environment
Based in: Dundalk Institute of Technology, Ireland
Objectives: Water column stratification patterns in lakes fundamentally affect how lakes function. Traditional lake monitoring typically occurs at weekly or lower frequency, and patterns of stratification and mixing when viewed through this low frequency filter appear to show gradual seasonal change. We believe that these patterns are strongly influenced by short-lived episodic events that occur over short time intervals, but have much longer lasting effects. These two types of change, gradual vs. episodic, can lead to very different levels of environmental stability while in the end accounting for similar seasonal patterns of thermal structure. The overall aim is to test the hypothesis that changes in lake thermal structure are strongly affected by short lived episodic events and to develop indexes of environmental change and stability based on differences in water temperature (density). This PhD will also identify the time scales that must be considered in modelling episodic events in lakes (WP 3). The ESR will use data from long term monitoring sites and from mesocosm experiments at the LakeLab sites. The specific objectives are to:
- Analyse high frequency lake water temperature records to define the distribution of stratification events by both magnitude and duration. Thresholds derived from these distributions will be used to define periods of mixing and stratification.
- Analyse return period of events of different magnitude, and the duration of relatively calm periods between mixing.
- Examine seasonal variation in lake thermal structure accounting for episodic changes and how these patterns and the role of episodic events vary between lakes with different climate and morphometry.
This student will be primarily based in Dundalk Institute of Technology supervised by Dr Eleanor Jennings, and co-supervised by and spend study time with Prof. Hans Peter Grossart, IGB Berlin, Germany. They will also spend time with Dr Ian Jones, CEH, UK. The PhD will be co-awarded by Dublin City University and University of Potsdam.