Advancing Maritime Transparent Cirrus Detection Using the Advanced Baseline Imager “Cirrus” Band

Abstract

We describe a quantitative evaluation of maritime transparent cirrus cloud detection, which is based on Geostationary Operational Environmental Satellite – 16 (GOES-16) and developed with collocated Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) profiling. The detection algorithm is developed using one month of collocated GOES-16 Advanced Baseline Imager (ABI) Channel 4 (1.378 μm) radiance and CALIOP 0.532 μm column-integrated cloud optical depth (COD). First, the relationships between the clear-sky 1.378 μm radiance, viewing/solar geometry, and precipitable water vapor (PWV) are characterized. Using machine learning techniques, it is shown that the total atmospheric pathlength, proxied by airmass factor (AMF), is a suitable replacement for viewing zenith and solar zenith angles alone, and that PWV is not a significant problem over ocean. Detection thresholds are computed using the Ch. 4 radiance as a function of AMF. The algorithm detects nearly 50% of sub-visual cirrus (COD < 0.03), 80% of transparent cirrus (0.03 < COD < 0.3), and 90% of opaque cirrus (COD > 0.3). Using a conservative radiance threshold results in 84% of cloudy pixels being correctly identified and 4% of clear-sky pixels being misidentified as cirrus. A semi-quantitative COD retrieval is developed for GOES ABI based on the observed relationship between CALIOP COD and 1.378 μm radiance. This study lays the groundwork for a more complex, operational GOES transparent cirrus detection algorithm. Future expansion includes an over-land algorithm, a more robust COD retrieval that is suitable for assimilation purposes, and downstream GOES products such as cirrus cloud microphysical property retrieval based on ABI infrared channels.

Estimating the Impact of Assimilating Cirrus Cloud–Contaminated Hyperspectral Infrared Radiances for Numerical Weather Prediction

“…Cirrus detection during daytime at 1.38 mm has shown promise. McHardy et al (2021) reports reliable cirrus detection at optical depths as low as 0.05 using the GOES-16 Advanced Baseline Imager 1.38 mm band. Since the VIIRS instrument (on board the same satellites as the CrIS sensor) contains a similar cirrus detection band near 1.38 mm, the VIIRS-CrIS fusion product (Baum et al 2019) could likely be quickly adapted for such efforts though examination of the cirrus detection/contamination in that product is required.…”

“…Since the VIIRS instrument (on board the same satellites as the CrIS sensor) contains a similar cirrus detection band near 1.38 mm, the VIIRS-CrIS fusion product (Baum et al 2019) could likely be quickly adapted for such efforts though examination of the cirrus detection/contamination in that product is required. While methods similar to that presented by McHardy et al (2021) would not remove all contaminating cirrus, it could be used to substantially decrease overall impact, even if only limited to daytime observations. Finally, given the sensitivity of HIS observations to layers beneath optically thin cirrus clouds, the methods of providing the forward and Jacobian radiative transfer model systems with static cloud optical properties ideally from state-of-the-art imager retrievals could be used to allow assimilation in cloudy scenes.…”

Novel Comparison of Pyrocumulonimbus Updrafts to Volcanic Eruptions and Supercell Thunderstorms Using Optical Flow Techniques

“…ABI's cirrus channel (Ch. 4, 1.378 μm), for instance, is effective at detecting and isolating transparent cirrus clouds (e.g., McHardy et al, 2021McHardy et al, , 2022. This channel could potentially be used to provide an "opaque view" of transparent smoke layers and thus a better input for optical flow techniques.…”

Summertime Continental Shallow Cumulus Cloud Detection Using GOES-16 Satellite and Ground-Based Stereo Cameras at the DOE ARM Southern Great Plains Site

“…Case selection by screening satellite images is necessary to ensure that there are no higher-level clouds above lower-level ShCu, such that the clouds detected using our method are valid shallow cumulus. Additional observations from the GOES ABI 1.38 channel can be useful to detect cirrus clouds [63].…”