The weather station installed on Suldenferner at the end of July 2014 (10.6°E / 46.5°N, 2745m) is now transmitting its data to Innsbruck, and will soon be visible on the institute website.
Unfortunately we do not have precipitation data from this station (first a wiring error, and then the gauge appears to have been destroyed by wind at some point). Nevertheless it is possible to have a look at the first data from this station showing the midsummer conditions (30th July – 17th September) at the station location which is over a thin cover of debris.The figure above shows the radiation fluxes measured over the surface: (top) incoming (SWin) and reflected (SWout) shortwave (solar) radiation; (middle) longwave radiation emitted from the atmosphere (LWin) and surface (LWout) shortwave radiation; (bottom) net shortwave and longwave radiation.
A high proportion of the incoming shortwave radiation (SWin – black) is absorbed at the debris covered surface. The mean albedo, which is the proportion of this radiation that is reflected (SWout – grey), to SWin, is 0.16, so only 16% of the incoming radiation is reflected from the surface. During each day the net shortwave radiation represents a large energy source to the surface, but of course goes to zero during the night.
The atmospheric longwave radiation (LWin – brown) is usually lower than that emitted from the surface (LWout – red). This is mainly because of the high surface temperature that the debris surface can reach during the day. The net longwave radiation is much smaller in magnitude than the net shortwave fluxes, and during the day is always negative, meaning a loss of energy from the surface, and sometimes positive during the night. At the end of the second week of August net longwave radiation is close to zero, which together with the low SWin, suggests that the weather station might be in the cloud.The figure above shows: air temperature (Ta – red) and dew point temperature (Td – blue); (middle) the difference (orange) between Ta and surface temperature (Ts – brown) ; (bottom) wind direction (light green) and speed (dark green).
The air temperature is usually above zero during this period, but the closeness of the Ta and Td records indicates that the air is often near saturation. During the daytime surface temperatures exceed 20°C, and the temperature gradient between the surface and air means that energy transfer is from the supraglacial surface surface towards the air. The strongest winds are associated with more northerly airflow.