Koldewey Station - Aerosol in the Polar Atmosphere

Measurements by Sun/Moon/Star Photometer

In recent years, much attention has been directed towards understanding the effects of aerosols on a variety of processes in the earth's atmosphere. Aerosols play an integral role in limiting visibility, they serve as nuclei for the formation of fog and cloud droplets, they affect the earth's radiative budget, and thus climate, both directly and indirectly, and they inhibit the propagation of electromagnetic radiation. The arctic aerosols, especially arctic haze and tropospheric ice crystals possibly have important climatic, ecological, and global change implication, and the Arctic measurements during polar night are necessary.  Since March 1991 regular measurements of the spectral optical depth of aerosols have been performed by using sun photometers at Ny-Ålesund. Photometer measurements, not only with sun light but also with light from the moon and from stars during the polar night, are used to determine the spectral optical depth of aerosols. The first successful measurements with moon as light sources in the Arctic were carried out from January to March 1995. 

Since January 1996 measurements of the spectral optical depth of aerosols during the polar night have been performed by using star photometer KOSP at Ny-Ålesund. Significant features of aerosol variation could be detected in the arctic atmosphere, like lower tropospheric ice crystals. For the measurements the light from different stars is used. It is planned that this instrument will be used for regular measurements in the future.