GOES Observations of Deep Convection in SRSOR with Mesoscale Atmospheric Motion Vectors: Can We Discriminate Between Ordinary and Supercellular Storms By Satellite?

Recent innovations in geostationary satellite (GOES) technology have led to experimentation with super rapid scan operations for GOES-R (SRSOR) data. SRSOR is a method of retrieving GOES satellite information with a one minute time scale. Subjective observations of GOES SRSOR data have suggested that rotational motion can be witnessed in supercell cloud tops by forecasters. Such observations served as motivation for the development and use of SRSOR mesoscale atmospheric motion vectors (mAMVs) to objectively identifying the rotational and divergent signatures. The mAMVs are generated by analyzing three infrared channels and one visible channel on GOES, and tracking targets of interest such as brightness gradients, minima and maxima over three time frames, each 1 minute apart. IR and water vapor data is then used with numerical weather prediction data to height-assign the observed wind vectors.

To date, five convective storm events are analyzed using the SRSOR mAMVs. Four of the five events were supercellular in nature, based on radar velocity analysis and storm reports. A single-pass Barnes analysis is used on the mAMV information to produce divergence and vorticity on a 1 km grid. Initial observations show that SRSOR mAMVs can resolve motion in highly transient data regions, such as the overshooting tops of deep convection. The added information allows for objective observations, and the discovery of consistent cloud top rotation in three of the four supercellular cases. The fourth case was somewhat problematic due to cirrus contamination above the storm of interest. Divergence provided timely information on the strength of the updraft, which showed a noticeable jump in one case ~15 minutes before an elevated tornado vortex signature was observed by radar. The ordinary convection did not yield persistent rotational signatures like the supercells, suggesting that it is possible to discriminate between ordinary and supercellular convection.

With the GOES-R launch coming in the near future, SRSOR mAMVs provide a useful new tool in observations of motions at deep convective cloud tops. One minute resolution satellite divergence and vorticity data can add new insights to the microphysical relationships between updraft strength and lightning within deep convection. Work is underway to use SRSOR mAMVs with lightning mapping arrays to examine the relationships of charge structure and intensity after convection becomes deep.