Abstract
Abstract. Ice cover on lakes is subject to atmospheric forcing from above and the influence of water dynamics and heat flux from below. One characteristic example of these influences in some large lakes, such as Lake Baikal in Russia, are the giant ice rings and the associated eddies under the ice cover. In April 2020 a giant ice ring appeared in southern Baikal, and a lens-like eddy was detected below the ice. We analysed the temporal changes of ice cover using satellite images from multiple satellite missions – MODIS on Terra and Aqua, Sentinel-1 SAR, Sentinel 2 MSI, Landsat 8, PlanetScope, satellite photography from the International Space Station, and radar altimetry data from Jason-3. Satellite imagery and meteorological data show unusual temporal changes of ice colour in April 2020, which were explained by water infiltration into the ice followed by the competing influences of cold air from above and the warm eddy below the ice. Tracking of ice floe displacement also makes it possible to estimate eddy currents and their influence on the upper water layer. Multi-satellite data contribute to a better understanding of the development of ice cover in the presence of eddies, the role of eddies in horizontal and vertical heat and mass exchange, and their impact on the chemistry and biology of the lakes and on human activity.
Highlights
Lakes can be viewed as an integrator of climate processes and a strong indicator of climate change
Giant ice rings were first observed in various places in Lake Baikal (Granin et al 2005, 2008, Kouraev et al, 2016), but later we found them in two other lakes – Lake Hövsgöl in Mongolia and Lake Teletskoye in Altai, Russia
We have used various satellite data to analyse changes in ice cover, and first we briefly describe various types of Lake Baikal ice cover (Sokol’nikov, 1960; Verbolov et al, 1965; Atlas of Lake Baikal, 1993; Shimaraev and Verbolov, 1998; Kouraev et al, 2007, 2008, 2016, 2019; Rusinek et al, 2012)
Summary
Lakes can be viewed as an integrator of climate processes and a strong indicator of climate change. The ice is thinner and appears darker in the ring region, and in the centre and outside the ring the ice is thicker and looks white like the surrounding undisturbed ice cover (Granin et al, 2015, 2018; Kouraev et al, 2016, 2018, 2019) Due to their large size, one of the best ways to observe and analyse ice rings is from satellite imagery. While the formation mechanism for this eddy is not clear, in this paper we would like to address how changes in ice cover can provide new information on the eddy itself To start with, this case presented quite an unusual development for an ice ring as seen from the satellite imagery (Fig. 2). We will demonstrate how multi-satellite imagery with high temporal frequency and high spatial resolution can help to monitor ice displacement and to reveal the size and impact of the underwater eddy
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