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Blokhina, N. S.; Ordanovich, A. E.; Savel'eva, O. S.

doi:10.1023/a:1010339919712

Cited by 17 publications

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“…An unusual natural phenomenon, the thermal bar, occurs in lakes of moderate latitudes twice a yearin autumn and spring. The thermal bar is a narrow zone of water masses sinking at the temperature of maximum density (~4 °C) and limits horizontal water exchange between central and coastal regions of a lake [1][2]. The effect of this phenomenon on the flow and temperature characteristics of lake water can lead to ecological risks associated with eutrophication processes, because the thermal bar divides a lake into two areas that vary widely in plankton and nutrient concentrations [3][4][5].…”

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confidence: 99%

On the role of wind direction in the thermal bar dynamics in autumn: A numerical study

Tsydenov

2023

IOP Conf. Ser.: Earth Environ. Sci.

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The effect of wind direction on the dynamics of the thermal bar in autumn was studied in Barguzin Bay of Lake Baikal by numerical modeling. An analysis of the temperature fields simulated showed that wind direction was essential to thermal bar development and temperature distribution. Easterly wind, in contrast to westerly wind, contributed to increased speed of the surface propagation of the thermal bar toward the open lake. The results presented here also demonstrate that autumnal cooling of Barguzin Bay was faster during easterly wind activity.

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Section: Introductionmentioning

confidence: 99%

On the role of wind direction in the thermal bar dynamics in autumn: A numerical study

Tsydenov

2023

IOP Conf. Ser.: Earth Environ. Sci.

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Effects of the anomalous temperature dependence of water density on surface gravity current

Bukreev

2005

J Appl Mech Tech Phys

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UDC 532.5.013.4 V. I. BukreevThis paper reports experimental results on the propagation of a plane water jet at a temperature above the maximum-density temperature (4 • C) along the free surface of initially quiescent water at a temperature of about 0 • C. For comparison, experiments were performed in which the temperatures of the lower and higher layers were more than 4 • C, other conditions being equal. The experiments revealed a number of new hydrodynamic effects, including peculiar flow instability and a fine structure of the density field at large times.Key words: maximum water density, hydromagnetic instability, fine structure of the density field.The temperature dependence of water density is nonmonotonic. Under normal conditions, the density is maximum at a temperature of about 4 • C, and at 0 • C , it is 0.07% lower (generally, the temperature of the maximum density T max depends on the pressure and impurity content). This anomalous property of water, compared to other fluids, is responsible for a number of effects, including hydrodynamic ones. When large masses of water at temperatures above and below T max come in contact, a layer of higher density surrounded by lower-density water is formed in the contact zone. Under gravity, the water particles in this layer are acted upon by a downward buoyancy force (the difference between the gravity and Archimedes force). This force is small. However, under certain conditions, often occurring in nature, it becomes substantial. In particular, the anomalous temperature dependence of water density plays an important role in heat and mass transfer processes in lake Baikal, where the density stratification is insignificant [1].The effect of seasonal thermal bar formation in lakes and water basins, in which water masses from the near-shore and deep-water areas of a water body come in contact, has been known since 1880. A review of studies of the thermal bar up to 1992 is contained in [2][3][4]. Of the later studies mention can be made of [5][6][7][8][9]. Emphasis has been placed primarily on full-scale and theoretical and computational studies. In the case of a thermal bar, the horizontal temperature gradient plays a determining role. The presence of vertical temperature gradients, including those with a layer of maximum density near the bottom, is a typical situation for deep water bodies at any time of year.The present paper considers some hydrodynamic processes resulting from contact of water masses at temperatures above and below T max for the flow shown schematically in Fig. 1. A water jet at temperature T 2 was discharged into quiescent water at temperature T 1 . In a strongly simplified formulation, this models the propagation of water flowing down a slope in a fresh water reservoir or the propagation of Selenga river water in lake Baikal. A comparison is made with the flow in the absence of anomalous effects with other conditions being equal.The experiments were conducted in a Plexiglas still-water channel of width B = 6 cm and wall thickness 0.6 cm. The channe...

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A numerical study of the thermal bar in shallow water during the autumn cooling

Tsydenov

2019

Journal of Great Lakes Research

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Cited by 17 publications

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On the role of wind direction in the thermal bar dynamics in autumn: A numerical study

On the role of wind direction in the thermal bar dynamics in autumn: A numerical study

Effects of the anomalous temperature dependence of water density on surface gravity current

A numerical study of the thermal bar in shallow water during the autumn cooling

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