Simultaneous observation of an above-anvil ice plume and plume-shaped BTD anomaly atop a convective storm

Abstract This study focuses on a convective storm that occurred late afternoon on 06 July 2010 above the Adriatic coast of the North Italy. A well-defined cold-U signature and a distinct above-anvil ice plume were present within the storm cloud top in Meteosat Spinning Enhanced Visible and InfraRed Imager (SEVIRI) infrared (IR) band imagery. The most interesting aspect of this case was the anomalous brightness temperature difference (BTD) between the 6.2 μm water vapor absorption (WV6.2) and the 10.8 μm infrared window (IR10.8) bands depicted with SEVIRI 5-minute rapid scan data. The BTD is usually positive above cold storm cloud tops. The positive BTD can be either closely correlated to the IR10.8 brightness temperature or exhibit various local “BTD anomalies”. While other recent studies focus on statistical characteristics of the positive BTD, we focus on a distinct BTD anomaly which developed at the top of the aforementioned storm. This case is unique because of the simultaneous occurrence of the BTD anomaly and a nearby ice plume. In this case the BTD anomaly resembles a distinct plume-like feature for a short period of time but had a rather irregular oval outline for most of its existence. The significance of the co-existence of both features is discussed as well as details of the BTD evolution.