Sensitivity of Tropical Cyclone Formation to Resolution‐Dependent and Independent Tracking Schemes in High‐Resolution Climate Model Simulations

Abstract

Abstract In the present study, global tropical cyclone (TC) formation characteristics are estimated using two fundamentally different Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Okubo‐Weiss zeta parameter (OWZP) tracking schemes in the reanalysis data and in a high‐resolution climate model with interannually varying sea surface temperatures. Both the schemes have a reasonable global geographical distribution of TC genesis locations with under simulation in the eastern North Atlantic and northwestern Australian regions. The mean annual TC frequency in the model is similar to observations using the CSIRO scheme but higher using the OWZP scheme, whereas the annual frequency in reanalysis using the OWZP scheme is similar to observations but halved using the CSIRO scheme. In the CSIRO scheme, both the resolution‐dependent thresholds and large‐scale climate may play a role for skilful TC formation statistics. In contrast, large‐scale climate leads to changes in OWZP TC detections. This highlights the importance of the large‐scale environment for TC detections in both the tracking schemes. The OWZP scheme can differentiate the monsoon lows from the actual TCs in the north Indian Ocean compared to the CSIRO scheme, which incorrectly detects them as TCs in the monsoon season. The distribution of TC lifetime in the model using the OWZP scheme is similar to observations. Conversely, the CSIRO scheme detected TCs have shorter lifetimes, perhaps due to intrinsic tracking scheme differences. Although the tracking schemes are fundamentally different, the study shows that there exist some similarities between them and for certain TC formation characteristics the OWZP scheme performs better compared to the CSIRO scheme.

Keywords

• tropical cyclone frequency
• tracking schemes
• high‐resolution climate model