In the summer of 1996 a glacio-meteorological experiment was carried out on Vatnajökull, Iceland (area 8000 km2;
altitude range: from sea level to about 2000 m). The main goal was to understand how the energy used in the melting of
snow and ice is delivered to the surface and what is the role of the ice cap's microclimate. In addition, the experiment
should deliver a data set that is useful for validation of satellite-derived surface properties like albedo. Many
meteorological stations were operated simultaneously on the ice cap for a 100-day period (see map below). Cable balloons
and radiosondes were used to probe the vertical structure of the boundary layer.
Data analysis is in full swing. It appears that katabatic flow shapes the microclimate of the glacier to a large
extent. The height of the wind maximum varies between a few and a few tens of meters. It is only during the passage of
intense storms that the katabatic wind in the melt zone disappears. Because of the low wind maximum present most of the
time, the evaluation of turbulent fluxes requires great care. Also, föhn-type flows occur every now and then. Such events
are significant, because turbulent exchange is quite high.
Global radiation increases significantly with altitude. Surface albedo varies enormously in space and time. Very low
values (0,1) are found at many places because of the melt out of volcanic ash layers. When considering the total melt
in the period 22 May - 31 August 1996, radiation provides typically two-thirds of the melt energy, turbulent exchange
one-third. At the stations high on the ice cap, turbulent exchange becomes less significant.