Tuesday, 22 January 2008
Examining a possible relationship between positive dominated storms and cloud-top ice crystal size
Exhibit Hall B (Ernest N. Morial Convention Center)
In a recent paper by Carey and Buffalo (2007), it was shown that thunderstorms with an anomalously large percent positive cloud-to-ground lightning strikes (CGs) tend to occur under certain thermodynamic conditions. In particular, storms with higher cloud bases and smaller warm cloud depths have a greater likelihood of having a larger percent positive CGs. Likewise, Lindsey et al. (2006) show that similar thermodynamic conditions lead to thunderstorms with particularly small cloud-top ice crystal sizes. Climatologies shown in each paper reveal that the regions of largest percent positive CGs overlap with the areas having smallest cloud-top crystals, but the spatial correlation is not exact. It stands to reason that a temporal correlation may exist between "positive" thunderstorms and storms having small cloud-top ice crystals.
This study provides results of a comparison between satellite-retrieved cloud-top ice effective radius and CG lightning data during the summer of 2007 over the central plains of the U.S. If a correlation exists, it provides evidence for the physical mechanisms responsible for both positive storms and clouds with anomalously small cloud-top ice crystals.