Automated Tropical Cloud Cluster Tracking and Analysis as a Front-End to the ADT

One of the requirements of the automated and now operational Advanced Dvorak Technique (ADT), a satellite-based objective tropical cyclone (TC) intensity estimation algorithm created by the Cooperative Institute for Meteorological Satellite Studies (CIMSS), is that it needs to be initialized by an official TC bulletin from either NHC or JTWC (depending on basin). This means the ADT can only begin operating upon the first designation of a TC as a depression or tropical storm. However, weaker tropical disturbances are routinely tracked and classified by operational satellite analysts using the familiar Dvorak Technique ‘T-number' classification scheme. Using a fully automated approach designed to mirror these operational procedures in classifying T# 1.0-2.0 tropical systems based on infrared (IR) and visible (VIS) imagery, the Tropical Cloud Cluster Tracker (TCCT) is being designed to mitigate this current limitation of the ADT. The TCCT algorithm employs an array of inputs that search a tropical domain to identify cloud clusters that meet empirically-determined thresholds. The inputs include pattern (IR composite image) matching, climatology of occurrence, IR brightness temperatures, existence of banded cloud structures in VIS imagery when available, and continuity/persistence in successive sampling. The TCCT is currently being developed, evaluated and tuned against a comprehensive dataset of operational Dvorak T-numbers provided by NOAA satellite analysts for Atlantic systems over a 10-year period. Once the TCCT becomes robust in identifying and tracking tropical disturbances, a T-number will be assigned to any systems that meet the threshold criteria. At this point the ADT will be initiated, and will follow the normal ADT procedures for estimating current intensity, but guided by a probability of intensification function provided by the Dvorak classification histories. Although the TCCT development is currently focused and functioning only in the tropical Atlantic, future work includes extending it to operate in all global TC basins in the near future.