Modelling water temperature beneath river ice covers

1990 ◽  
Vol 17 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Philip Marsh
Keyword(s):  
Heat Flux ◽  
Water Temperature ◽  
Water Depth ◽  
Frictional Heating ◽  
Ice Cover ◽  
Heat Fluxes ◽  
River Ice ◽  
Simple Method ◽  
Ice Melt ◽  
Bed Roughness

The water temperature beneath river ice covers has an important influence on the heat flux to the overlying ice cover and on ice melt. Measurements of water temperature beneath the Liard River ice cover showed that prior to spring breakup, the water temperature was always between 0.0 and 0.025 °C, with important cross-channel and diurnal variations. The lowest temperatures were controlled by the bed heat flux and frictional heating, while variations above these minimum values were explained by changes in solar radiation. Using measurements of these heat fluxes, in conjunction with measurements of ice and bed roughness, water depth and velocity, and slope, a simple method which assumes the similarity between heat and momentum transfer was able to accurately predict water temperatures beneath the ice cover. During breakup when the river had both ice-free and ice-covered sections, water temperatures rose to a few degrees above 0 °C. When this water entered an ice-covered reach, the water temperature declined rapidly to near 0 °C within 10 km. This temperature decay was predicted from measurements of the initial temperature, ice and bed roughness, and water depth. Key words: water temperature, ice, thermal regime, ice melt.

Water temperature and heat flux at the base of river ice covers

1987 ◽  
Vol 14 (1) ◽  
pp. 33-50 ◽  
Author(s):  
Philip Marsh ◽  
Terry D Prowse
Keyword(s):  
Heat Flux ◽  
Water Temperature ◽  
River Ice

scholarly journals Components of near-surface energy balance derived from satellite soundings – Part 2: Noontime latent heat flux

2014 ◽  
Vol 11 (24) ◽  
pp. 7369-7382 ◽  
Author(s):  
K. Mallick ◽  
A. Jarvis ◽  
G. Wohlfahrt ◽  
G. Kiely ◽  
T. Hirano ◽  
...  
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Land Surface ◽  
Vegetation Index ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Simple Method ◽  
Near Surface ◽  
Available Energy

Abstract. This paper introduces a relatively simple method for recovering global fields of latent heat flux. The method focuses on specifying Bowen ratio estimates through exploiting air temperature and vapour pressure measurements obtained from infrared soundings of the AIRS (Atmospheric Infrared Sounder) sensor onboard NASA's Aqua platform. Through combining these Bowen ratio retrievals with satellite surface net available energy data, we have specified estimates of global noontime surface latent heat flux at the 1°×1° scale. These estimates were provisionally evaluated against data from 30 terrestrial tower flux sites covering a broad spectrum of biomes. Taking monthly average 13:30 data for 2003, this revealed promising agreement between the satellite and tower measurements of latent heat flux, with a pooled root-mean-square deviation of 79 W m−2, and no significant bias. However, this success partly arose as a product of the underspecification of the AIRS Bowen ratio compensating for the underspecification of the AIRS net available energy, suggesting further refinement of the approach is required. The error analysis suggested that the landscape level variability in enhanced vegetation index (EVI) and land surface temperature contributed significantly to the statistical metric of the predicted latent heat fluxes.

scholarly journals Experimental characterization of the hypersonic flow around a cuboid

2020 ◽  
Vol 61 (7) ◽  
Author(s):  
Thomas W. Rees ◽  
Tom B. Fisher ◽  
Paul J. K. Bruce ◽  
Jim A. Merrifield ◽  
Mark K. Quinn
Keyword(s):  
Heat Flux ◽  
Hypersonic Flow ◽  
Stagnation Point ◽  
Separation Bubble ◽  
Reynolds Numbers ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Simple Method ◽  
High Reynolds

Abstract Understanding the hypersonic flow around faceted shapes is important in the context of the fragmentation and demise of satellites undergoing uncontrolled atmospheric entry. To better understand the physics of such flows, as well as the satellite demise process, we perform an experimental study of the Mach 5 flow around a cuboid geometry in the University of Manchester High SuperSonic Tunnel. Heat fluxes are measured using infrared thermography and a 3D inverse heat conduction solution, and flow features are imaged using schlieren photography. Measurements are taken at a range of Reynolds numbers from $${40.0 \times 10^3}$$ 40.0 × 10 3 to $${549 \times 10^3}$$ 549 × 10 3 . The schlieren results suggest the presence of a separation bubble at the windward edge of the cube at high Reynolds numbers. High heat fluxes are observed near corners and edges, which are caused by boundary-layer thinning. Additionally, on the side (off-stagnation) faces of the cube, we observe wedge-shaped regions of high heat flux emanating from the windward corners of the cube. We attribute these to vortical structures being generated by the strong expansion around the cube’s corners. We also observe that the stagnation point of the cube is off-centre of the windward face, which we propose is due to sting flex under aerodynamic loading. Finally, we propose a simple method of calculating the stagnation point heat flux to a cube, as well as relations which can be used to predict hypersonic heat fluxes to cuboid geometries such as satellites during atmospheric re-entry. Graphic abstract

A new similarity model for the stratified under-ice boundary layer in lakes and its application to ice-covered Lake Baikal

2020 ◽  
Author(s):  
Georgiy Kirillin ◽  
Ilya Aslamov ◽  
Nikolai Granin ◽  
Roman Zdorovennov
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Lake Baikal ◽  
Strong Dependence ◽  
Shear Velocity ◽  
Ice Cover ◽  
Heat Fluxes ◽  
Solid Boundary ◽  
Buoyancy Frequency ◽  
Ice Water

<p>Seasonal ice cover on lakes and polar seas creates seasonally developing boundary layer at the ice base with specific features: fixed temperature at the solid boundary and stable density stratification beneath. Turbulent transport in the boundary layer determines the ice growth and melting conditions at the ice-water interface, especially in large lakes and marginal seas, where large-scale water circulation can produce highly variable mixing conditions. Since the boundary mixing under ice is difficult to measure, existing models of ice cover dynamics usually neglect or parameterize it in a very simplistic form. We propose a model of the turbulent energy budget in the stably stratified boundary layer under ice, based on the length scale incorporating the dissipation rate and the buoyancy frequency (Dougherty-Ozmidov scaling). The model was verified on fine-scale measurements in Lake Baikal and demonstrated a good agreement with data. The measured ice-water heat fluxes in were among the largest reported in lakes (up to 40 W m<sup>−2</sup>) and scaled well against the proposed relationship. The model yields a scaling relationship for the ice-water heat flux as a function of the shear velocity squared that suggests the traditional bulk parameterizations may significantly underestimate the ice-water heat flux, especially at strong under-ice current velocities. The ultimate result consists in a strong dependence of the water-ice heat flux on the shear velocity under ice. </p>

A Pathway Connecting the Monsoonal Heating to the Rapid Arctic Ice Melt*

2015 ◽  
Vol 72 (1) ◽  
pp. 5-34 ◽  
Author(s):  
T. N. Krishnamurti ◽  
Ruby Krishnamurti ◽  
Sweta Das ◽  
Vinay Kumar ◽  
A. Jayakumar ◽  
...  
Keyword(s):  
Heat Flux ◽  
Asian Summer Monsoon ◽  
Canadian Arctic ◽  
Heat Content ◽  
Heat Fluxes ◽  
South Asian Summer Monsoon ◽  
Vertical Column ◽  
Ice Melt ◽  
Wave Trains ◽  
Arctic Ice

Abstract This study provides a monsoonal link to the rapid Arctic ice melt. Each year the planetary-scale African–Asian monsoonal outflow near the tropopause carries a large anticyclonic gyre that has a longitudinal spread that occupies nearly half of the entire tropics. In recent years, the South Asian summer monsoon has experienced increased rainfall over northwestern India and Pakistan and it has also contributed to more intense local anticyclonic outflows from this region. The western lobes of these intense upper-high-pressure areas carry outflows with large heat fluxes from the monsoon belt toward central Asia and eventually to the region of the rapid ice melt of the Canadian Arctic. In this study this spectacular pathway has been defined from airflow trajectories, heat content, and heat flux anomalies. Most of these show slow increasing trends in the last 20 years. The monsoonal connection to the rapid Arctic ice melt is a new contribution of this study. This is shown from the passage of a vertical column of large positive values of the heat content anomaly that can be traced from the Asian monsoon belt to the Canadian Arctic. The heat flux along these episodic and intermittently active pathways is shown to be considerably larger than the atmospheric poleward flux across latitude circles and from the oceans. This study contrasts these thermodynamic wave trains (defining this pathway) for the more conventional dynamic wave trains.

scholarly journals Relative impacts of increases of solar radiation and air temperature on the temperature of surface water in a shallow, eutrophic lake

2021 ◽  
Author(s):  
Ryuichiro Shinohara ◽  
Yoji Tanaka ◽  
Ariyo Kanno ◽  
Kazuo Matsushige
Keyword(s):  
Heat Flux ◽  
Surface Water ◽  
Solar Radiation ◽  
Water Temperature ◽  
Air Temperature ◽  
Heat Fluxes ◽  
Shortwave Radiation ◽  
Surface Water Temperature ◽  
Lake Kasumigaura ◽  
Lake Surface

Abstract We monitored lake surface water temperatures from 1992 to 2019 in Lake Kasumigaura, a shallow lake in Japan. We hypothesized that increases of shortwave radiation had increased surface water temperatures and heat fluxes more than had the increases of air temperature. We used the heat flux analyses and the sensitivity analyses to test the hypothesis. The fluxes of solar radiation gradually increased during the study period in a manner consistent with the phenomenon of global brightening. The increase was especially apparent in the spring. The rate of increase of surface water temperature was especially significant in May. Air temperature did not significantly increase in May, but it increased significantly in June (0.40 °C decade−1). A sensitivity analysis of the heat fluxes at the lake surface (shortwave radiation, longwave radiation, latent heat flux, and sensible heat flux) revealed that surface water temperature was more sensitive to changes of shortwave radiation than to air temperature during the spring. Although other factors such as inflows of groundwater and river water may also have impacted surface water temperatures, the increase of solar radiation appeared to be the major factor responsible for the increase of surface water temperature during the spring in Lake Kasumigaura.

Thermal budget of river ice covers during breakup

1989 ◽  
Vol 16 (1) ◽  
pp. 62-71 ◽  
Author(s):  
T. D. Prowse ◽  
P. Marsh
Keyword(s):  
Heat Input ◽  
Leading Edge ◽  
Field Measurements ◽  
Open Water ◽  
Heat Fluxes ◽  
River Ice ◽  
Ice Jams ◽  
Frazil Ice ◽  
Ice Melt ◽  
Ice Roughness

The magnitude and relative importance of atmosheric (air–ice) and hydrothermal (water–ice) heat fluxes to intact and fragmented river ice covers are studied for the case of a thermal breakup. Based on field measurements obtained from the Liard River, the atmospheric sources are shown to be dominant during the period of intact ice cover. Radiation was the primary heat source, but its effect was reduced by a granulation of the decaying columnar ice which increased the cover albedo to that comparable for melting snow. The hydrothermal heat input, even with frazil ice entrained within the flow, was comparable to that from atmospheric sources under low melt conditions. The hydrothermal heat flux dramatically increased with the arrival of the breakup front because of a rapid rise in water temperature and an increase in subsurface ice roughness. Higher surface roughness and lower albedo of the fragmented ice also increased the atmospheric heat fluxes, but these were small relative to the hydrothermal heat input near the leading edge of open water. Key words: floating ice, ice breakup, ice jams, ice melt.

THE EFFECT OF NONUNIFORM AXIAL HEAT FLUX DISTRIBUTION ON CRITICAL HEAT FLUXES WITH POTASSIUM IN TUBES

1970 ◽  
Author(s):  
I. T. Aladyev ◽  
I. G. Gorlov ◽  
O. S. Fedynsky
Keyword(s):  
Heat Flux ◽  
Flux Distribution ◽  
Heat Fluxes ◽  
Heat Flux Distribution ◽  
Axial Heat

scholarly journals Assessing IDDES-Based Wall-Modeled Large-Eddy Simulation (WMLES) for Separated Flows with Heat Transfer

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 246
Author(s):  
Rozie Zangeneh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Large Eddy Simulation ◽  
Skin Friction ◽  
Heat Fluxes ◽  
Separated Flows ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Isothermal Wall

The Wall-modeled Large-eddy Simulation (WMLES) methods are commonly accompanied with an underprediction of the skin friction and a deviation of the velocity profile. The widely-used Improved Delayed Detached Eddy Simulation (IDDES) method is suggested to improve the prediction of the mean skin friction when it acts as WMLES, as claimed by the original authors. However, the model tested only on flow configurations with no heat transfer. This study takes a systematic approach to assess the performance of the IDDES model for separated flows with heat transfer. Separated flows on an isothermal wall and walls with mild and intense heat fluxes are considered. For the case of the wall with heat flux, the skin friction and Stanton number are underpredicted by the IDDES model however, the underprediction is less significant for the isothermal wall case. The simulations of the cases with intense wall heat transfer reveal an interesting dependence on the heat flux level supplied; as the heat flux increases, the IDDES model declines to predict the accurate skin friction.

scholarly journals Drift kinetic theory of alpha transport by tokamak perturbations

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Elizabeth A. Tolman ◽  
Peter J. Catto
Keyword(s):  
Heat Flux ◽  
Kinetic Theory ◽  
Alpha Particle ◽  
Heat Fluxes ◽  
Alpha Particles ◽  
Alpha Power ◽  
Mode Amplitude ◽  
Effective Collision Frequency ◽  
Perturbation Frequency ◽  
Particle Confinement

Upcoming tokamak experiments fuelled with deuterium and tritium are expected to have large alpha particle populations. Such experiments motivate new attention to the theory of alpha particle confinement and transport. A key topic is the interaction of alpha particles with perturbations to the tokamak fields, including those from ripple and magnetohydrodynamic modes like Alfvén eigenmodes. These perturbations can transport alphas, leading to changed localization of alpha heating, loss of alpha power and damage to device walls. Alpha interaction with these perturbations is often studied with single-particle theory. In contrast, we derive a drift kinetic theory to calculate the alpha heat flux resulting from arbitrary perturbation frequency and periodicity (provided these can be studied drift kinetically). Novel features of the theory include the retention of a large effective collision frequency resulting from the resonant alpha collisional boundary layer, correlated interactions over many poloidal transits and finite orbit effects. Heat fluxes are considered for the example cases of ripple and the toroidal Alfvén eigenmode (TAE). The ripple heat flux is small. The TAE heat flux is significant and scales with the square of the perturbation amplitude, allowing the derivation of constraints on mode amplitude for avoidance of significant alpha depletion. A simple saturation condition suggests that TAEs in one upcoming experiment will not cause significant alpha transport via the mechanisms in this theory. However, saturation above the level suggested by the simple condition, but within numerical and experimental experience, which could be accompanied by the onset of stochasticity, could cause significant transport.

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