A review of the remote sensing of lower tropospheric thermodynamic profiles and its indispensable role for the understanding and the simulation of water and energy cycles

摘要

A review of remote sensing technology for lower tropospheric thermodynamic (TD) profiling is\udpresented with focus on high accuracy and high temporal-vertical resolution. The contributions of these\udinstruments to the understanding of the Earth system are assessed with respect to radiative transfer, land\udsurface-atmosphere feedback, convection initiation, and data assimilation. We demonstrate that for progress\udin weather and climate research, TD profilers are essential. These observational systems must resolve\udgradients of humidity and temperature in the stable or unstable atmospheric surface layer close to the\udground, in the mixed layer, in the interfacial layer—usually characterized by an inversion—and the lower\udtroposphere. A thorough analysis of the current observing systems is performed revealing significant gaps\udthat must be addressed to fulfill existing needs. We analyze whether current and future passive and active\udremote sensing systems can close these gaps. A methodological analysis and demonstration of measurement\udcapabilities with respect to bias and precision is executed both for passive and active remote sensing\udincluding passive infrared and microwave spectroscopy, the global navigation satellite system, as well as\udwater vapor and temperature Raman lidar and water vapor differential absorption lidar. Whereas passive\udremote sensing systems are already mature with respect to operational applications, active remote sensing\udsystems require further engineering to become operational in networks. However, active remote sensing\udsystems provide a smaller bias as well as higher temporal and vertical resolutions. For a suitable mesoscale\udnetwork design, TD profiler system developments should be intensified and dedicated observing system\udsimulation experiments should be performed.