ATMO-DEL: Determination of the atmospheric delay via line-of-sight modelling and measurements of the tropospheric composition and the ionospheric electron distribution.

在研究单位的子项目“时钟计量学”中，将以比以前更高的精度指定GNSS（全球导航卫星系统）卫星上的发射机到地面接收器的大气延迟，以满足向研究单位提出的建议要求。这一目标将通过将瞄准线的专用延迟模型与大气条件的测量相结合来实现。延迟模型由对流层部分和电离层部分组成，对流层部分采用柔性折射率剖面。对流层测量将在德国南部（49.14N, 12.86E）的Geodätic Wettzell观测站进行，该观测站是由BKG“Bundesamt fr Karthographie und Geodäsie”运营的GNSS参考站。沿着视距测量大气水蒸气、温度、云和气溶胶将使用微波和红外光谱仪。电离层的电子含量由卫星测量确定，并插值到GNSS地面站的位置。这些测量和模型将用于研究大气成分和温度的变化对延迟测定精度的影响。这包括大气、云和气溶胶中水蒸气含量在空间和时间上的快速波动。该研究单元提供了一个独特的环境来实现这一目标，并将大气延迟的错误计算引起的误差与其他误差源（例如接收器电子设备的不确定性）分离开来。测量结果将用作延迟模型的输入，但也提供给研究单位内的其他项目。

In the sub-project of the research unit "Clockmetrology" the atmospheric delay from a transmitter on a GNSS (Global Navigation Satellite System) satellite to the receiver on the ground will be specified with higher accuracy than before to meet the requirements specified in the proposal to the research unit. This goal will be reached via a combination of a dedicated delay model of the line of sight with measurements of atmospheric conditions. The delay model consists of a tropospheric part, which uses flexible profiles of refraction indices and an ionospheric part. The tropospheric measurements will be taken at the Geodätic Observatorium Wettzell, GOW, in Southern Germany (49.14N, 12.86E), a GNSS reference station operated by the "Bundesamt für Karthographie und Geodäsie", BKG. Measurements of atmospheric water vapor, temperature, clouds and aerosols along the line-of-sight will be done using microwave and infrared spectrometers. The electron content of the ionosphere is determined from satellite measurements and interpolated to the place of the GNSS ground station. The measurements together with the model will be used to investigate the effect of the variability of the atmospheric composition and temperature on the accuracy of the delay determination. This includes fast spatial and temporal fluctuations in the water vapor content of the atmosphere, clouds and aerosols. The research unit provides an unique environment to reach this goal and separate the error caused by a miscalculation of the atmospheric delay from other error sources, e.g. uncertainties in the electronics of the receiver. The measurements will be used as an input to the delay model, but also supplied to other projects within the research unit.