Jökull - 01.01.2005, Qupperneq 125

Energy balance of Brúarjökull and the August 2004 floods in the river Jökla.
Figure 4. Measured and calculated daily melting at the three AWSs during the summer 2004. Black: direct
measurement and green: calculated from the total energy supplied for melting. – Mæld og reiknuð leysing í
veðurstöðvum á Brúarjökli.
alent. The total energy (Mc) for a melting glacier sur-
face is expressed as
Mc = R + H + Hp , (1)
where R = Qi − Qo + Ii − Io is the net radiation
obtained from the observed radiation components and
H = Hd + Hl is the net turbulent heat flux calculated
from the observed temperature, humidity and wind-
speed within the boundary layer; one- and two-level
models with a stability factor (Monin and Obukhov
method) were used to calculate the sensible (Hd) and
latent (Hl) heat fluxes (e.g. Björnsson, 1972; Greuell
and Genthon, 2003).
Heat supplied by precipitation (Hp) is considered
negligible and the ablation calculated as
as =
⎧
⎪⎨
⎪⎩
Mc
ρL
; Mc ≥ 0
0; Mc < 0
, (2)
where ρ = 103 kg m−3 is the density of water and
L = 3.3 · 105Jkg−1 is the specific latent heat of melt-
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