Vertical Correlation Lengths as a Tool for Quantifying Profiling Capabilities in the Planetary Boundary Layer and Troposphere and Defining Future Requirements

Abstract

The planetary boundary layer (PBL) is the portion of the troposphere that is directly influenced by the presence of the Earth's surface. The thermodynamic structure of this layer exhibits a wide variety of characteristics across the globe. In 2018 the National Academies of Sciences, Engineering, and Medicine Space Studies Board recommended that U.S. agencies consider the advancement of technologies for the remote sensing of the PBL thermodynamic structure and height. This paper provides a quantitative assessment of the PBL thermodynamic structure across various climate regimes using the highest vertical resolution radiosonde measurements available from Department of Energy Atmospheric Radiation Measurement research sites and informs the requirements of a future PBL mission. To do this, this paper introduces a method to characterize the vertical scales of temperature and water vapor correlation. This method is used to analyze radiosonde, Atmospheric Emitted Radiance Interferometer (AERI), and Atmospheric Infrared Sounder (AIRS) data sets. The AIRS Level 2 Version 7 product is shown to achieve a vertical correlation length in temperature that is generally similar to high vertical resolution radiosonde data, but shows much larger water vapor correlation lengths (>1 km) than is reported by the radiosonde data (<500 m). Contrastingly, the ground‐based infrared TROPoe (AERI) retrieval is able to nearly recreate the vertical correlation patterns of the radiosondes in temperature below 4,000 m, and recreated the water vapor correlation lengths at two times that of the radiosonde data below 4,000 m. This is a well‐known qualitative result that is quantified by the use of this metric.