Time lapse imagery of the ice-off event at Lake Tarfala, Kebnekaise Mountains, northern Sweden, summer 2022

Nina Kirchner, Annika Granebeck, Jamie Barnett, Daniella Lillieroth Charalambous

This dataset contains images of Lake Tarfala taken every 2 hours during the period from 22 June to 28 July 2022. During this period, the surface of Lake Tarfala transitions from being ice-covered to ice-free, an event referred to as "ice-off".

The dataset can be used to observe the ice-off event and to assign a date (or, rather, a time interval) to it. Knowledge of lake ice phenology, i.e. seasonal formation and loss of the lacustrine ice cover, is of importance since the timing of ice-off impacts lake processes such as stratification and vertical mixing.

The pictures were acquired using a camera positioned on the mountain flank along Lake Tarfala’s north-eastern shore, at 1220 m above sea level. In total, there are 444 images.

Download data

Scientific highlights

This dataset allows to assign a precise date to the ice-off event at Lake Tarfala in summer 2022. Defining ice-off as the first occasion after the ice-covered winter season on which the lake becomes completely ice-free and remains so for the rest of the summer, it was attained on 27 July 2022.

Precise knowledge of the ice-off date can be used to:

1. Assist in understanding lake mixing processes.
2. Better constrain numerical models computing ice-off.
3. Provide a complement to ice-off dates derived from satellite imagery, which is notoriously difficult in polar alpine environments due to persistent cloud cover and long polar nights.
4. Lend support to alternative definitions of ice-off.
5. Contribute to knowledge of lake ice phenology in high altitude Arctic environments under current climate change.

Some notable events in the time-lapse imagery of the diminishing lake ice cover include:

• 24 June: Commence of ice cover melt in the north-western lake-corner where Kebnepakte Glacier drains into Lake Tarfala (right margin of picture, e.g. at 00:10).
• 1⁠ – ⁠7 July: Retreat of ice cover along eastern lake shoreline (foreground of picture, most visible on 7 July at 04:10) and increasing number of melt features on the central lake ice cover, mimicking surface meltwater ponds (most visible 6 July at 18:10).
• 8 July: Crack formations in the southern part of the lake ice cover (left margin of picture, e.g. at 22:10). Repeated occurrence of the phenomenon in the central parts of the ice surface on 15 July (at 04:10).
• 17 July: Onset of lakewide drift and disintegration of ice floes.
• 21 July: Inflow of sediment-rich streamwater from stream network on the eastern lake bank (left margin of picture, at 12:10 until 16:10). Repeated occurrence of the phenomenon can be seen on 27 July (at 06:10 until 12:10).

Note that the camera produces black-white images under certain light conditions, such as under some low-visibility weather conditions.

Citation

Nina Kirchner, Annika Granebeck, Jamie Barnett, Daniella Lillieroth Charalambous (2023) Time lapse imagery of the ice-off event at Lake Tarfala, Kebnekaise Mountains, northern Sweden, summer 2022. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/tarfala-kirchner-2023-ice-off-2022-1

Data description

The dataset consists of image files (JPG) of Lake Tarfala, with the date and time (Swedish daylight saving time, UTC+2) included in each photo.

The pictures were acquired using a camera positioned on the mountain flank along Lake Tarfala’s north-eastern shore, at ~67.9° N, 18.6° E, at 1220 m above sea level.

The data were collected using a Hunter Orion Trail Camera 4G. The camera elevation is 1.8 m above ground. Each JPG file has a size of ~2.4 MB. The total size of the dataset is ~927 MB.

In order to protect personal data in accordance with the EU General Data Protection Regulation (GDPR), small parts of four images have been concealed.

During a few short periods, fog, snow and/or rain obscures the view of the lake.

Comments

The support of our co-workers on the Arctic Avenue activity Lake thermal and mixing dynamics under changing climate (J. Weckström, K. Weckström, A. Korhola, and F. Schenk) is gratefully acknowledged.