LEXPLORE PLATFORM

LéXPLORE Letters No. 14

This newsletter was generated on the 28-02-2023.

The figures below are showing data for the period 07-02-2023 to 21-02-2023.

Until today, Thetis sampled 3477 depth profiles on Lake Geneva. In this Newsletter we show 53 profiles, so just 1.52% of the recorded data. The complete data set is available at Datalakes.

Data highlights of this issue

We continue to record a very dry winter. We measured basically no precipitation in this issue’s period and the very distinct diurnal air temperature cycle is a good indicator for cloud-free sky conditions. On top of that we recorded very calm waters, with little wave activities due to a calm atmosphere. This leaves the water column cold and uniform.

Around the 18th and 19th February, air temperatures are rising, with daily maximum temperatures around 10 degree Celsius. Together with the incoming solar radiation, this is enough to heat up the top of the water column slightly, increase biological activity where light is available and with that increase oxygen concentrations in the top few meters of the lake. The response of the lake to the atmospheric conditions is rather immediate, within 24 hours of the air getting warmer, and can also nicely be seen in the daily water temperature and chlorophyll anomalies, which show positive values for the upper lake levels at the end of the highlighted period.

All in all a textbook lake ecosystem response to a little “heat wave” at the end of the meteorological winter.

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, 14, https://lexplore.info/wp-content/uploads/2023/02/lexplore-letters-2023-02-28.html