Investigation of Abrupt Decreases in Atmospherically Backscattered Laser Energy.

摘要

The objective of this study was to determine if two abrupt decreases, as a function of altitude, in atmospherically backscattered laser energy were directly associated with temperature inversion particulate trapping. A ruby lidar system was employed to detect the sharp decreases in laser energy at altitudes of 2.22 km and 2.56 km on the night of 1 November 1974. Aerosols of radius r<0. 1 micrometer and 1 < r < 3 micrometers, collected onboard the da Vinci balloon gondola on the same night provided aerosol density versus altitude profiles. Temperature and relative humidity altitude profiles, recorded with radiosonde instruments at 2045, 1 November, and 0415, 2 November, revealed the absence of temperature inversions within the laser probed altitude interval. Abrupt changes in relative humidity failed to induce similar changes in the reflected laser energy. The sharp decreases in backscattered laser energy are attributed to a negative density gradient of the 1 micrometer to 3 micrometers radius anhydrous areosols. This gradient was not located above a temperature inversion and therefore, in this case, the changes in laser signal were found to be unrelated to any temperature inversion trapping mechanism. (Author)