Лëд и снег (Sep 2021)
Formation of an ice dam in the lower reaches of the Mezen and Kuloy rivers from 1983 to 2020 (the White Sea basin)
Abstract
The features of ice cover formation within the macro-tidal estuaries of the Mezen River and the Kuloy River are considered. The investigated rivers flow into the Mezen Bay of the White Sea. The main sources of information for the ice monitoring were the high spatial resolution images from the satellites Landsat 5‑8 and Sentinel 1.2 with addition of medium spatial resolution images of MODIS/Terra and VIIRS/SuomiNPP. Every year, zones of continuous hummocks and ice dams are formed in the estuaries, which exert influence upon characteristics of the tidal waves. The fast ice and drifting ice areas are observed below the ice dam. Above the dam, amplitude the tidal fluctuations in the water level is reduced by 3–4 times. According to the data for the period 2017–2020, the area of relatively smooth ice cover is located at the distance of 48–49 km above the mouth of the Mezen River and 40–42 km above the same of the Kuloy River. Advancing of the ice edge to the mouth is accompanied by the formation of hummocky ice bridges, the position of which is confined to the narrowing and sharp turns of the channel. According to satellite images, it is established that the ice dam changes its position from year to year. In the period from 1983 to 2020, on the Mezen River, the ice dam was located at a distance of 21.0 to 30.5 km from the mouth, and on the Kuloy – from 13.7 to 27.5 km above the mouth. The position of the ice dam is weather dependent. In severe winters, the dam is located closer to the mouth gauge line. Snow, falling in November and December on areas of open water, delays advancing of the ice edge to the mouth. For Mezen, the relation between the position of the ice dam and three following predictors had been obtained: the sum of precipitation for November and December at the air temperature below –5 °C, the sum of air temperatures below –5 °C for January and March, and the sum of positive air temperatures for February. The proposed dependence made it possible to restore the positions of the ice dam for the years which were not provided with satellite data. These are 1994 and 1999.
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