Detecting boundary layer moisture convergence with GOES-R ABI bands

A new study has begun which examines whether boundary-layer moisture convergence can be detected from satellite. Although the idea behind using the so-called "split window" (~11 – 12 µm) to estimate precipitable water has been around for nearly 30 years, only with the improved Advanced Baseline Imagery (ABI) aboard the GOES-R series of satellites is the spatial resolution and radiometric characteristics of the instrument sufficient to pinpoint regions of moisture convergence. To examine this possibility, a thunderstorm event that occurred on 27 June 2005 was simulated with the RAMS model, and synthetic imagery was produced from 2.25 through 13.3 µm for a six hour period with a temporal sampling rate of five minutes. During this period, thunderstorms developed over southeast Wyoming, and cold cloud tops are evident in all synthetic images. Prior to the development of clouds, however, channel differencing was able to detect the growth of water vapor plumes in the boundary layer. Such plumes were the result of the vertical transport of water vapor due to horizontal convergence. As a result of the increased depth of water vapor, the positive brightness temperature difference (10.35 – 12.3 µm) increased in value. Such an increase did not occur in the near vicinity, thus making the plume signature stand out. This presentation will describe the results of our study and will show how this idea may be used to predict the formation of clouds and storms as much as a few hours in advance.