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.
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)
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
