Updated Stereo Camera Cloudiness Map Product Released for Evaluation

 
Published: 20 March 2023

Clouds Optically Gridded by Stereo (COGS) data from ARM’s Southern Great Plains atmospheric observatory are presented for May 4, 2018. The top plot shows the number of cloudy grids as a function of time and height above the ground. Cloud base heights estimated as the 1% of the cloudy grid heights are marked with black dots. The bottom plot presents vertically projected cloud fraction. Both plots cover 18:04 UTC through the rest of the day. Maximum cloud fraction is shown over 0.8 (before 21:32 UTC), and the minimum is 0.0 after 18:04 and 23:15 UTC.
Clouds Optically Gridded by Stereo (COGS) data from ARM’s Southern Great Plains atmospheric observatory are presented for May 4, 2018. The top plot shows the number of cloudy grids as a function of time and height above the ground. Cloud base heights estimated as the 1% of the cloudy grid heights are marked with black dots. The bottom plot presents vertically projected cloud fraction. Cloud fraction is calculated as the fraction of vertically projected cloudy grids over the total number of available grids at the cloud base height.

An updated version of the Clouds Optically Gridded by Stereo value-added product (COGS VAP) is now available for evaluation.

This improved product, cogs.c1, replaces the previously announced cogspi.c1. It includes not only a four-dimensional (4D) map of cloudiness but also a vertically projected cloud fraction and cloud base height estimate. The map of cloudiness is generated by multiview stereo reconstruction using a ring of stereo cameras at the Atmospheric Radiation Measurement (ARM) user facility’s Southern Great Plains (SGP) atmospheric observatory.

The additions in COGS provide more useful information for studying the life cycles and macrophysical attributes of shallow cumulus clouds.

COGS is generated by stitching together three-dimensional (3D) reconstructed cloud points from the three pairs of ARM stereo cameras at the SGP. It covers a 6-by-6-by-6-kilometer region of the SGP Central Facility centered at the position of the Doppler lidar. The grid resolution is 50 meters in horizontal and vertical directions and 20 seconds in time.

Evaluation data are available for shallow cumuli events from September 1, 2017, through October 27, 2019. Access the data in the ARM Data Center. (Go here to create an account to download the data.)

The images and cloud point data used to generate COGS are also available in the ARM Data Center as the Point Cloud of Cloud Points (PCCP) VAP.

More information about COGS is available on the VAP web page. To ask questions or provide feedback to improve this evaluation product, please contact Rusen Öktem or David M. Romps.

To cite the COGS data, please use doi:10.5439/1877293.

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ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.