Are temperatures changing differently across seasons?
The vast majority of past trends work has focused on JAS (summertime) surface temperature trends. Some work has looked below the surface, but generally have focused at coarse, non-specific metrics like schmidt stability or whole lake mean water temp.
Seasonality matters. Fishes spawn in spring. Peak summertime temperatures might affect phytoplankton blooms. Zooplankton care about stratification.
Seasonality has also been unexplored in the context of cross-depth trends. How does the full 2d matrix of trends evolve across season and depth?
We can take a detailed look at temperature trends using good ol' sens slope. With high-density data, we can get depth-discrete, season-specific trends. Using an unbiased GENMOM simulation (1979-2000 with hierarchical secchi selection (order: year-specific in-situ, satellite, then lake mean), this is how Sparkling looks:
Sparkling
Note, color brightness-trend magnitude are not the same between model runs, but white, red and blue are always trends of 0, warming, and cooling respectively. Here's the same for Mendota:
Mendota
Ok, interesting, we're seeing some fall warming that is stronger than warming in other season. We also note that our fall warming potentially dominates warming during other times of the year (when viewed from a whole-lake level).
Empirical 2d trend analysis
Can we ask the same questions and visualize trends similarly using manually sampled in-situ data? Maybe!
Crystal
Mendota
Sparkling
We may not have the timeseries length in Mendota to get such a detailed view of trends. But both SP and CR seem to show stronger fall warming over other seasons. There's also the puzzle of the week 20 cooling. It's a surprisingly robust pattern. I've done that to death, I'm not sure what's going on.
Are temperatures changing differently across seasons?
The vast majority of past trends work has focused on JAS (summertime) surface temperature trends. Some work has looked below the surface, but generally have focused at coarse, non-specific metrics like schmidt stability or whole lake mean water temp.
Seasonality matters. Fishes spawn in spring. Peak summertime temperatures might affect phytoplankton blooms. Zooplankton care about stratification.
Seasonality has also been unexplored in the context of cross-depth trends. How does the full 2d matrix of trends evolve across season and depth?
We can take a detailed look at temperature trends using good ol' sens slope. With high-density data, we can get depth-discrete, season-specific trends. Using an unbiased GENMOM simulation (1979-2000 with hierarchical secchi selection (order: year-specific in-situ, satellite, then lake mean), this is how Sparkling looks:
Sparkling
Note, color brightness-trend magnitude are not the same between model runs, but white, red and blue are always trends of 0, warming, and cooling respectively. Here's the same for Mendota:
Mendota
Ok, interesting, we're seeing some fall warming that is stronger than warming in other season. We also note that our fall warming potentially dominates warming during other times of the year (when viewed from a whole-lake level).
Empirical 2d trend analysis
Can we ask the same questions and visualize trends similarly using manually sampled in-situ data? Maybe!
Crystal
Mendota
Sparkling
We may not have the timeseries length in Mendota to get such a detailed view of trends. But both SP and CR seem to show stronger fall warming over other seasons. There's also the puzzle of the week 20 cooling. It's a surprisingly robust pattern. I've done that to death, I'm not sure what's going on.