SAFARI 2000 Modeled Tropospheric Air Mass Trajectories, Dry Season 2000

The ETA Forecast Trajectory Model was used to produce forecasts of air-parcel trajectories twice a day at three pressure levels over seven sites in Southern Africa for the period August 14, 2000 to September 23, 2000. These sites are Durban, Middleburg, Pietersburg, and Springbok, South Africa; Maun, Botswana; Mongu, Zambia; and Windhoek, Namibia. The twice daily three-dimensional wind field (at 0000 and 1200 UTC) was used as input to the trajectory model. By integrating the vertical motion of the air parcels over a period of time, the trajectory model was able to forecast the net vertical displacement of air parcels during 12-hour periods. The resulting trajectory plots represent the three-dimensional transport of air in time and can be used to examine what is happening in the low-to-mid troposphere during flight and ground-based observations. These levels are most significant in terms of the thermodynamic structure of the troposphere, especially the stable layers and accumulation of material between and below them, as well containing the major levels of subsidence over the subcontinent. The trajectory model output and thermodynamic profiles of the troposphere were used to position aircraft for sampling trace gases, aerosols and other species during the SAFARI 2000 field campaign and to predict regions of high aerosol and trace gas concentrations downwind.The model output data are daily forward and backward trajectory plots at 850 hPa, 700 hPa, and 500 hPa pressure levels for each location. The plots are provided as JPEG images with coordinate, date, and time stamps.

该数据集采用ETA预测轨迹模型，于2000年8月14日至9月23日期间，对南非七个地点在三个气压层级上的空气团轨迹进行每日两次的预测。这些地点包括南非的德班、米德尔堡、皮特堡和斯普林博克；博茨瓦纳的玛温；赞比亚的蒙古；以及纳米比亚的风城。每日两次的输入为0000和1200 UTC时次的三维风场。通过整合空气团在一段时间内的垂直运动，轨迹模型能够预测12小时期间的空气团净垂直位移。生成的轨迹图展现了空气在时间维度上的三维传输，可用于分析飞行和地面观测期间对流层低至中层的变化。这些层级在对流层的热力学结构中尤为重要，特别是稳定层以及它们之间的物质积累，同时还包括大陆上空的沉降主要层级。轨迹模型输出和对流层热力学剖面被用于定位飞机在SAFARI 2000野外考察期间采集痕量气体、气溶胶及其他物种，并预测下风向高气溶胶和痕量气体浓度区域。模型输出数据为每日850 hPa、700 hPa和500 hPa气压层级的正向和反向轨迹图，以JPEG图像形式提供，并附有坐标、日期和时间戳。