Synergy of Satellite- and Ground-Based Observations for Continuous Monitoring of Atmospheric Stability, Liquid Water Path, and Integrated Water Vapor: Theoretical Evaluations Using Reanalysis and Neural Networks

Abstract

<jats:title>Abstract</jats:title> <jats:p>Atmospheric stability plays an essential role in the evolution of weather events. While the upper troposphere is sampled by satellite sensors, and in situ sensors measure the atmospheric state close to the surface, only sporadic information from radiosondes or aircraft observations is available in the planetary boundary layer. Ground-based remote sensing offers the possibility to continuously and automatically monitor the atmospheric state in the boundary layer. Microwave radiometers (MWR) provide temporally resolved temperature and humidity profiles in the boundary layer and accurate values of integrated water vapor and liquid water path, and the differential absorption lidar (DIAL) measures humidity profiles with high vertical and temporal resolution up to 3000-m height. Both instruments have the potential to complement satellite observations by additional information from the lowest atmospheric layers, particularly under cloudy conditions. This study presents a neural network retrieval for stability indices, integrated water vapor, and liquid water path from simulated satellite- and ground-based measurements based on the COSMO regional reanalysis (COSMO-REA2). Focusing on the temporal resolution, the satellite-based instruments considered in the study are the currently operational Spinning Enhanced Visible and Infrared Imager (SEVIRI) and the future Infrared Sounder (IRS), both in geostationary orbit. Relative to the retrieval based on satellite observations, the additional ground-based MWR/DIAL measurements provide valuable improvements not only in the presence of clouds, which represent a limiting factor for infrared SEVIRI/IRS, but also under clear-sky conditions. The root-mean-square error for convective available potential energy, for instance, is reduced by 24% if IRS observations are complemented by ground-based MWR measurements.</jats:p>

Ground-based temperature and humidity profiling: combining active and passive remote sensors

“…Figure 6 shows cDFS profiles from the MWRz-only and AERI-only temperature and water vapor retrievals during a 2 h period when the sky transitioned from virtually clear sky to overcast. Three profiles with different LWP amounts (2, 10, and 60 g m −2 , where the infrared is essentially opaque for the last; Turner, 2007) are shown. The cloud base was at 1100 m and was assumed to be 100 m thick (there was no way to determine cloud top from other observations at the site).…”

Challenges in Diurnal Humidity Analysis from Cellular Microwave Links (CML) over Germany

“…In addition, there is a limited ability to deploy humidity gauges in heterogeneous terrain or in areas with complex topography. Satellites do allow for a large area to be covered in high spatial and temporal resolution, but are frequently not accurate enough in the atmospheric boundary layer and depend on surface emissivity and cloud cover [4]. Radiosondes, which are typically launched only 2-4 times a day, also provide very limited information due to generally much low spatial and temporal resolution.…”

EUMETNET opens to microwave radiometers for operational thermodynamical profiling in Europe

“…Retrieved products such as water vapour or cloud liquid water contents and temperature profiles are essential for human experts in fore-and nowcasting (and for NWP if the assimilation of retrievals is preferred over the assimilation of brightness temperatures). -Thanks to the synchronous measurements of humidity and temperature information, MWR allow for the independent derivation of Stability or Forecast Indices (FI) (Cimini et al 2015;Kulikov et al 2020;Toporov and Löhnert 2020). Owing to the rapid evolution of convective situations the continuous monitoring of FI from MWR is a big advantage over the traditional radiosondes which are usually available at an interval of 12 h. In addition, WMO's statement of guidance for aeronautical meteorology lists stability indices explicitely as requirements (van der Meulen 2018).…”