TY - JOUR
T1 - A method for monitoring glacier mass balance using satellite albedo measurements
T2 - Application to Vatnajökull, Iceland
AU - de Ruyter de Wildt, Martijn S.
AU - Oerlemans, Johannes
AU - Björnsson, Helgi
PY - 2002
Y1 - 2002
N2 - We compare satellite albedo images of Vatnajökull, Iceland, with mass-balance measurements for the years 1991-99. We find that the equilibrium line is mostly not visible when it is located above its position of the previous year(s). Equilibrium-line detection is further hindered by clouds and a gradual transition between ice and firn or snow. Consequently, firn-line elevation at the end of the melting season is not particularly useful for estimating the annual mass balance. Instead, we propose to study the mean albedo of the entire ice cap throughout the melting season so that all available information about the surface albedo is taken into account. The mean net potential global radiation, which can be estimated from the mean surface albedo alone, both depends on and influences summer melt. It also depends on winter precipitation and, integrated over the melting season, is found to relate linearly to the specific mass balance B (r = 0.87 and 0.94 for different outlets of Vatnajökull). B can be estimated quantitatively when this relation is known and qualitatively when it is not. The uncertainty in the satellite-derived value of B is 0.5-0.8 m w.e., which for Vatnajökull corresponds to about 27% of the interannual variability of B.
AB - We compare satellite albedo images of Vatnajökull, Iceland, with mass-balance measurements for the years 1991-99. We find that the equilibrium line is mostly not visible when it is located above its position of the previous year(s). Equilibrium-line detection is further hindered by clouds and a gradual transition between ice and firn or snow. Consequently, firn-line elevation at the end of the melting season is not particularly useful for estimating the annual mass balance. Instead, we propose to study the mean albedo of the entire ice cap throughout the melting season so that all available information about the surface albedo is taken into account. The mean net potential global radiation, which can be estimated from the mean surface albedo alone, both depends on and influences summer melt. It also depends on winter precipitation and, integrated over the melting season, is found to relate linearly to the specific mass balance B (r = 0.87 and 0.94 for different outlets of Vatnajökull). B can be estimated quantitatively when this relation is known and qualitatively when it is not. The uncertainty in the satellite-derived value of B is 0.5-0.8 m w.e., which for Vatnajökull corresponds to about 27% of the interannual variability of B.
UR - http://www.scopus.com/inward/record.url?scp=0036909217&partnerID=8YFLogxK
U2 - 10.3189/172756502781831458
DO - 10.3189/172756502781831458
M3 - Article
AN - SCOPUS:0036909217
SN - 0022-1430
VL - 48
SP - 267
EP - 278
JO - Journal of Glaciology
JF - Journal of Glaciology
IS - 161
ER -