MétéoSuisse

Shortwave radiation from the sun is the prime energy source driving temperature at Earth's surface. Climatological conditions that foster live on Earth however, are only reached with atmospheric greenhouse gases absorbing and reemitting thermal longwave radiation back to the surface, thereby acting as second energy source elevating the surface temperature on average by 33°C. The atmospheric greenhouse effect and its relation to temperature and humidity is investigated by studying the individual radiative fluxes. Consider the following relations:

Surface temperature is directly related to absorbed shortwave and longwave radiation

Surface reflection of shortwave radiation (albedo) is cooling the surface

Clouds modulate radiative fluxes and temperature by shortwave cooling and longwave warming

Aerosols scatter and absorb shortwave radiation, cooling the surface but heating the atmosphere

Greenhouse gases absorb and reemit longwave radiation and increase the temperature

Water vapor is the most abundant greenhouse gas and increases with temperature.

Picture of the ASRB station at Gornergrat (Swiss Alps) with Monte Rosa in the background

ASRB station colocated at the Meteoswiss ENET station at Gornergrat (3110 m a.s.l.). Thygan measuring temperature and humidity (left) and ventilated pyranometer and pyrgeometer (right) measuring shortwave respectively longwave downward radiation.

The investigations are based on accurate measurements of downward and upward shortwave and longwave radiative fluxes at screen level height ( 2 meter above surface ) at ten stations of the Alpine Surface Radiation Budget (ASRB) network. ASRB stations are colocated with MeteoSwiss automatic meteorological stations and are distributed between 370 and 3580 m a.s.l. and over an area of about 200 by 200 km2 in the Alps (central Europa, latitude ~ 46°N).

Publications

Altitude dependence of surface radiation fluxes and cloud effect in the Alp:
Marty, Ch., et al., Theor. Appl. Climatol. 72, 137-155 (2002)
Clear sky index and automatic cloud amount detection:
Marty, Ch., and R. Philipona, Geophys. Res. Lett., 27, 2649-2652 (2000)
Dürr, B., and R. Philipona, J. Geophys. Res., 109, (2004)
Comparison of modeled and observed cloud-free longwave downward radiation:
Dürr, B., et al., Met. Zeitschrift, 14, (2005)
Greenhouse effect, radiative forcing and temperature and humidity increase:
Philipona, R., et al., Geophys. Res. Lett., 31, (2004)
Philipona, R., and B. Dürr, Geophys. Res. Lett., 31, (2004)
Philipona, R., et al., Geophys. Res. Lett., 32, (2005)

Contact: Rolf Philipona

Alpine Surface Radiation Budget (ASRB) and Greenhouse Effect investigations

This project aims at investigating the surface radiation budget at different altitudes and its relation to the greenhouse effect and to temperature and humidity in a changing climate.

Publications