The moisture transport history to the south of the Tibetan Plateau was modeled using the meteorological data provided by NCEP in this paper, and the modeled results were compared with the measured δ18O in the south of the Tibetan Plateau. The relation between δ18O in precipitation in the south of the Tibetan Plateau and moisture trajectories was discussed. The results show that the extremely low δ18O in precipitation in the south of the Tibetan Plateau is always related to the moisture from the low-level sea surface evaporation. The long-distance transport of moisture also contributes to low δ18O in precipitation probably due to the rainout process during moisture transport. It is also found that low δ18O in precipitation is also related with deep layer transport of moisture, and with intensive condensation in the upper layers of the atmosphere, resulting in low δ18O because of depletion of heavy isotopes in deep condensation. However, high δ18O in precipitation whether in monsoon period or not is always companied with moisture coming from the upper layers, and the moisture is from northern or western sides of the plateau. The interpretation of the modeled results is in agreement with the isotope fractionation processes.
Light detection and ranging (LiDAR) scanners are increasingly being used to measure discontinuity orientations on rock cuts to eliminate the bias and hazards of manual measurements which are also time consuming and somewhat subjective. Typically LiDAR data sets (point clouds) are analyzed by sophisticated algorithms that break down when conditions are not ideal, for example when some of the discontinuities are obscured by vegetation, or when significant portions of the rock face are composed of fractured facets, weathering generated surfaces, or anything that should not be identified as a discontinuity for the purposes of slope stability analysis. This paper presents a simple LiDAR point cloud viewer that allows the user to view the point cloud, identify discontinuities, pick three points on the surface (plane) of each discontinuity, and generate discontinuity orientations using the three-point method. Additionally, a test of our 3-D LiDAR viewer for discontinuity orientations on rock cuts in the United States of America and Canada is presented. 相似文献