21 August 2023
The Atmospheric Emitted Radiance Interferometer Optimal Estimation (AERIoe) value-added product (VAP) provides boundary-layer profiles of temperature and water vapor mixing ratio and liquid cloud retrievals. AERIoe helps retrieve profiles in both clear and cloudy conditions so users can better understand the processes taking place in the boundary layer. The high-time-resolution retrievals of boundary-layer thermodynamic profiles provide new information about the evolution of the boundary layer that is difficult to measure.
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Compared with liquid water path (LWP) retrievals from the Microwave Radiometer Retrievals (MWRRET) VAP, the LWP retrievals in optically thin clouds from AERIoe allow for better quantification of cloud microphysical properties in clouds such as shallow cumulus.
The AERIoe retrieval algorithm (Turner and Löhnert 2014; Turner and Blumberg 2019) uses an optimal estimation framework to derive cloud and thermodynamic profiles using AERI radiances and additional inputs.
Because AERIoe can be run for more cases, including cloudy conditions, and multiple locations, this product is preferred for use over the AERI Profiles of Water Vapor and Temperature (AERIPROF) VAP at the Southern Great Plains atmospheric observatory.
Although AERIoe provides fine vertical-resolution retrievals within the boundary layer, the vertical information content from infrared retrievals is fairly coarse above the boundary layer, so the retrieval misses some fine-scale structure and inversions.
Currently, AERIoe retrieves LWP and effective radius of liquid cloud layers. The LWP retrieval is expected to be quite good for liquid clouds with low LWP, unlike LWP retrievals from microwave radiometers alone. When microwave radiometer brightness temperatures are also available and of good quality, the retrieval should also give good values at higher LWPs.
A known problem in the current retrieval is that the infrared retrievals can misclassify ice as liquid. Currently, the forward model only includes absorption and not scattering, which can lead to erroneous retrievals of non-zero LWP when only ice clouds are present.
References:
Turner DD and U Loehnert. 2014. “Information Content and Uncertainties in Thermodynamic Profiles and Liquid Cloud Properties Retrieved from the Ground-Based Atmospheric Emitted Radiance Interferometer (AERI).” Journal of Applied Meteorology and Climatology, 53(3), https://doi.org10.1175/jamc-d-13-0126.1
Turner D and W Blumberg. 2019. “Improvements to the AERIoe Thermodynamic Profile Retrieval Algorithm.” IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(5), https://doi.org/10.1109/JSTARS.2018.2874968