Detection of convective initiation using Meteosat SEVIRI: implementation in and verification with the tracking and nowcasting algorithm Cb-TRAM

Abstract

Abstract. In this paper a new detection scheme for convective initiation (CI) under day and night conditions is presented. The new algorithm combines the strengths of two existing methods for detecting CI with geostationary satellite data. It uses the channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard Meteosat Second Generation (MSG). For the new algorithm five infrared (IR) criteria from the Satellite Convection Analysis and Tracking algorithm (SATCAST) and one high-resolution visible channel (HRV) criteria from Cb-TRAM were adapted. This set of criteria aims to identify the typical development of quickly developing convective cells in an early stage. The different criteria include time trends of the 10.8 IR channel, and IR channel differences, as well as their time trends. To provide the trend fields an optical-flow-based method is used: the pyramidal matching algorithm, which is part of Cb-TRAM. The new detection scheme is implemented in Cb-TRAM, and is verified for seven days which comprise different weather situations in central Europe. Contrasted with the original early-stage detection scheme of Cb-TRAM, skill scores are provided. From the comparison against detections of later thunderstorm stages, which are also provided by Cb-TRAM, a decrease in false prior warnings (false alarm ratio) from 91 to 81% is presented, an increase of the critical success index from 7.4 to 12.7%, and a decrease of the BIAS from 320 to 146% for normal scan mode. Similar trends are found for rapid scan mode. Most obvious is the decline of false alarms found for the synoptic class "cold air" masses.

Detection of deterministic and probabilistic convection initiation using Himawari-8 Advanced Himawari Imager data

“…Therefore, these geostationary satellites can be extremely useful in CI nowcasting. Previous studies developed CI nowcasting algorithms for geostationary satellites by determining a threshold or a range of values of T b at specific channels, and their spectral and/or temporal differences (Mecikalski and Bedka, 2006;Mecikalski et al, 2008;Walker et al, 2012;Morel and Senesi, 2002;Jewett and Mecikalski, 2013;Merk and Zinner, 2013;Siewert et al, 2010;Sobajima, 2012;Han et al, 2015). Geostationary Operational Environmental Satellite (GOES) systems and Meteorological Second Generation (MSG) are the representative geostationary satellites operated at the National Oceanic and Atmospheric Administration (NOAA) and European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), respectively.…”

Study of Mesoscale Cloud System Oscillations Capable of Producing Convective Gravity Waves

“…Nevertheless, the criteria chosen are widely used worldwide and have been already proven effective in the detection and monitoring convection in the studies where they were proposed and performed [25]. Additionally, the algorithm used in this study is well tested and has been already used in previous studies on cloud convection and thresholding criteria [19,[22][23][24].…”

“…In the current version of the algorithm, four different criteria are used in order to detect mesoscale convective cells (Table 1). At this point, it is mentioned that similar sets of criteria are widely used efficiently for the early detection of cloud convection using satellite imagery, e.g., [25]. Regarding the overlapping procedure of the algorithm which defines the continuity of the cloud cells in the different time-steps as parts of an MCS, the threshold value of 25% common areal extent was used.…”

Cloud and DNI nowcasting with MSG/SEVIRI for the optimized operation of concentrating solar power plants

“…For the detection of convective clouds, procedures of the Cb-TRAM algorithm (CumulonimBus TRacking And Monitoring; Zinner et al, 2008Zinner et al, , 2013Merk and Zinner, 2013) have been examined and exploited in this work. Cb-TRAM divides convection into three stages:…”

“…Furthermore, for both cloud types (liquid water and ice), cloud optical thickness and effective radius are derived from two solar channels using APICS. In APICS, SEVIRI channels centered at 0.6 and 1.6 µm are used based on the method by Nakajima and King (1990) and Nakajima and Nakajima (1995). The lookup tables required for this application have been computed with the radiative transfer model libRadtran (Mayer and Kylling, 2005;Emde et al, 2016) using a midlatitude standard atmosphere (Anderson et al, 1986), a typical continental aerosol load, a rural type aerosol in the boundary layer, background aerosol above 2 km, springsummer conditions and a visibility of 50 km (Shettle, 1989).…”