A Synergy of Ground-based and Space-based Sensors as a Potential Solution for Sounding the Planetary Boundary Layer

Both the National Research Council in 2009 and the 2017 NASA Decadal Survey have highlighted need for improved thermodynamic soundings of the planetary boundary layer (PBL) The National Research Council suggested the development of a nationwide network of ground-based profilers to supplement space-based profilers in order to improve observations of the PBL. One of the instruments that would fulfill the requirements outlined by the National Research Council for this ground-based network would be the Atmospheric Emitted Radiance Interferometer (AERI). AERI has been used extensively in calibration and validation studies of space-based instruments in addition to process studies of the PBL in research settings. AERI also has a multidecade data record as part of the Atmospheric Radiation Measurement (ARM) Program. It has been shown that a combined retrieval consisting of a synergy of radiance observations from multiple sensors would maximize the information content provided by the space-based and ground-based sensors and would lead to improved retrievals over those provided by each instrument separately or those provided by a post hoc combination of individual retrievals. Through synthetic information content analyses, we demonstrate that a combination of AERI with the Cross-track Infrared Sounder (CrIS) on S-NPP and NOAA-20 would double the information content from the surface up to 700 hPa compared to CrIS alone. A synergy of AERI and CrIS also significantly improves vertical resolution from the surface up to 1000 m above ground level (AGL) compared to CrIS alone. Uncertainties of the retrieval are reduced from the surface to 1000 m AGL level. Introducing a ground-based sensor to the observing system also provides a potential solution to IR sounding in cloudy environments. In scenes with optically thick clouds, the retrieval is informed by CrIS above the cloud and AERI below the cloud. Preliminary results from applying this combined retrieval in a real-world setting reinforce the results from the synthetic analysis.