OPTICAL PARAMETRIC OSCILLATORS: DIAL in the Alps measures tropospheric water vapor

摘要

Water vapor accounts for somewhere around two-thirds of the greenhouse effect in Earth's atmosphere; thus, accurate information on the distribution of water vapor in the atmosphere is crucial for models of Earth's climate. In particular, more accurate knowledge of the vertical distribution of water vapor in the upper troposphere, which radiates longwave-infrared radiation into space, is needed. Researchers at the Environmental Research Station Schneefernerhaus (Umweltforschungsstation Schneefernerhaus, or UFS), high in the German Alps, have developed a high-power differential-absorption lidar (DIAL) that can measure the vertical distribution of water vapor in the free troposphere (3 to 12 km above sea level; the free troposphere is the portion of the troposphere above by the temperature-inversion layer at approximately 2 km above sea level).