LEXPLORE PLATFORM

LéXPLORE Letters No. 13

This newsletter was generated on the 14-02-2023.

The figures below are showing data for the period 24-01-2023 to 07-02-2023.

Until today, Thetis sampled 3383 depth profiles on Lake Geneva. In this Newsletter we show 58 profiles, so just 1.71% of the recorded data. The complete data set is available at Datalakes.

Data highlights of this issue

After several weeks of recording winter days that were never sampled before, we finally again have some past data to compare to. But we get ahead of ourselves.

We see very cold and uniform water profiles, with temperatures between 6 and 7 degrees Celsius. The water column continues to cool down as winter progresses. Coming out of a period of freezing air temperatures, the water body continues to emit long wave radiation into the cooler atmosphere. Low wave heights and no precipitation further contribute to the uniformity of the water column. Low nutrient input and cold temperatures are the foundation for the low biological activity. As a side note, the sparse to non-existent winter precipitation led to historically low snow cover in the Swiss Alps. We will see what that means for future runoff and the impact of that on Lake Geneva in the coming seasons.

Looking at the water temperature anomalies, we see that the water column is slightly cooler than in previously measured years. Clear sky, cool winter days definitely helped to achieve that. After the very positive temperature anomalies in autumn and early winter, this is a refreshing sight.

What is displayed

Data from the Thetis profiler:

  • Water Temperature in °Celsius

  • Water Temperature Anomaly on daily resolution with respect to to the available daily climatology from Thetis so far in Kelvin

  • Dissolved Oxygen mg/L

  • Oxygen Saturation in %

  • Chlorophyll A in μg/L

  • Chlorophyll A Anomaly on daily resolution with respect to to the available daily climatology from Thetis so far in μg/L

  • Backscattering of light 700 nm in 1.e-2 m-1, representing zooplankton or larger particles in the water

Data from the automatic weather station:

  • Air Temperature in °Celsius

  • Wind Speend in m/s

  • Precipitation in mm

Data from the wave buoy:

  • Wave height in decimeter

Authorship and further information

This newsletter is created by EPFL, specifically Martin Wegmann.

For more information about LéXPLORE, contacting us and possibilities to visit the platform: lexplore.info

If you want to know more about the Chlorophyll distribution across Lake Geneva, have a look at the satellite data map by our colleagues at CIPEL.

If you want to know more about the water temperature distribution across Lake Geneva, have a look at the lake reanalysis and forecasts by our colleagues at EAWAG.

If you want to use figures from the LéXPLORE Letters, you can use the following citation:

EPFL, Limnology Center 2023: LéXPLORE Letters, 13, https://lexplore.info/wp-content/uploads/2023/02/lexplore-letters-2023-02-14.html