Effects on the glaciers

Storyboard

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Glaciers

Description

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Ablation cup

Equation

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To calculate the ablation rate (melting speed), we\'ll assume that the glacier has a height h and is at a temperature $\Delta T$ below the melting point. The energy captured by a layer of height $\Delta x$ is partly conducted into the glacier, contributing to the melting of the layer and its warming. If l is the latent heat and $\rho_e$ the ice density, a volume element with surface $S$ and height $\Delta x$ will require the energy

$\Delta Ql = S\Delta x l \rho_e$



to melt.

To heat it up to the melting temperature $\Delta T_m$, it will require

$\Delta Q_c = S\Delta x\rho_ec\Delta T_m$



where c is the specific heat. Lastly, thermal conduction will remove heat

$\Delta Q_{\lambda}=\displaystyle\frac{\lambda S\Delta T_b}{h}\Delta t$



where $\lambda$ is the thermal conductivity, $\Delta T_b$ is the base-surface temperature difference, and $\Delta t$ is the elapsed time.

Therefore, the total heat will be

$\Delta Q_l + \Delta Q_c + \Delta Q_{\lambda} = (1 - a_{ev})(1 - \gamma_v)S I_s\Delta t$



which, after replacing with the expressions, becomes

$S\Delta xl\rho_e + S\Delta x\rho_ec\Delta T_m + (\lambda/h)S \Delta T_b \Delta t = (1 - a_{ev})(1 - \gamma_v)S I_s\Delta t$



Solving for \Delta x, we get the expression for the melting speed

$ v_a =\displaystyle\frac{(1 - a_{ev} )(1 - \gamma_v ) I_s - ( \lambda / h ) \Delta T_b }{ \rho_e (l + c \Delta T_m )}$

$a_{ev}$
Albedo del Hielo
$-$
7514
$h_e$
Altura capa de hielo
$m$
7530
$l_e$
Calor Latente del Hielo
$J/kg$
7520
$c_e$
Capacidad calorica del Hielo
$J/kg K$
7519
$\gamma_v$
Cobertura Zona Glaciar
$-$
7515
$\lambda$
Conductividad termica del Hielo
$J/m s K$
7517
$\rho_e$
Densidad del Hielo
$kg/m^3$
7521
$\delta T_b$
Diferencia Temperatura Glaciar Superficie-Base
$K$
7522
$\Delta T_e$
Diferencia Temperatura para deretir Superficie
$K$
7523
$I_s$
Intensidad del Sol
$W/m^2$
7516
$v_a$
Velocidad de Deshielos
$m/s$
7511

Hence, an increase in temperature leads to an increase in the ablation rate.

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Accumulation Rate

Equation

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The accumulation rate, denoted as v_c, is calculated from the amount of snow, \Delta x, that falls within a time interval, \Delta t, as per the formula:

$ v_c =\displaystyle\frac{ \Delta x }{ \Delta t }$

$\Delta x$
Altura deshielo
$m$
7613
$\Delta t$
Tiempo deshielo
$s$
7614
$v_c$
Velocidad de Nevación
$m/s$
7512

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Mass balance rate

Equation

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Solar radiation is partly reflected and partly absorbed by the surface. If $I_s$ is the radiation flux, $a_{ev}$ is the Earth\'s visible albedo, and $\gamma_v$ is the coverage factor, the absorbed fraction is

$(1 - a_{ev})(1 -\gamma_v)I_s$



The heat supplied is partly conducted into the glacier\'s interior and partly contributes to melting a layer of thickness $\Delta x$ in a time $\Delta t$.

In this way, the glacier\'s surface would decrease at an ablation rate (melting speed)

$v_a =\displaystyle\frac{\Delta x}{\Delta t}$



due to the melting effect, while it would grow at an accumulation rate $v_c$ (snow deposition speed) due to the effect of snow being deposited on its surface. Therefore, melting would occur if the total velocity

$ v_b = v_c - v_a$

$v_a$
Velocidad de Deshielos
$m/s$
7511
$v_c$
Velocidad de Nevación
$m/s$
7512
$v_b$
Velocidad Efectiva de Deshielo
$m/s$
7513

turns out to be negative.

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Glacier height variation

Equation

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La taza de balance de masa que se calcula de la taza de acumulación y la taza de ablación

$ v_b = v_c - v_a$



permite estimar la variación en la altura especifica del glaciar (en un lugar en particular)

$\Delta h=v_b\Delta t$

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