An Empirical Model for Predicting the Decay of Tropical Cyclone Wind Speed after Landfall over the Indian Region

Abstract

An empirical model for predicting the maximum surface wind speed associated with a tropical cyclone after crossing the east coast of India is described. The model parameters are determined from the database of 19 recent cyclones. The model is based upon the assumption that tropical cyclone winds decay exponentially after landfall. A method for correcting the forecast during subsequent observation hours is also presented. Results show that without the correction factor the absolute mean error ranges from 6.1 to 4.9 kt (1 kt ϭ 0.5144 m s Ϫ1 ) and the root-mean-square error ranges from 7.9 to 5.6 kt, with both decreasing over time. With the incorporation of the correction procedure, a significant improvement in the forecast skill is noticed for the case in which it is tested using the dependent sample. The model is expected to be very useful to operational forecasters.

Operational tropical cyclone intensity prediction—an empirical technique

“…Roy Bhowmik et al (2005) very recently used a similar empirical technique for predicting the decay of the wind speed of a TC over the Indian region after the latter had reached landfall.…”

High-Impact Weather Events over the SAARC Region

“…apart from disaster management. In view of this, the decay model (Roy Bhowmik et al 2005) has been used for real time forecasting of decaying intensity (after landfall) of TCs. Flow diagram of the five-step objective Cyclone Prediction System (CPS) is shown in Fig.…”

“…A rapid intensification index (RII) is used for the probability forecast of rapid intensification (RI) (Kotal and Roy Bhowmik 2013). A decay model has been used for real time forecasting of decaying intensity after the landfall (Roy Bhowmik et al 2005).…”

Statistical modelling of tropical cyclones' longevity after landfall in Australia

“…This aspect has been captured in empirical models for the wind speeds of landfalling TCs with the basic assumption that the decay rate is proportional to the wind speed (Kaplan and DeMaria 1995). Kaplan and DeMaria's models were developed for the United States but other such models have been developed for other parts of the world, for example, Roy Bhowmik et al (2005) developed a model for the Bay of Bengal coasts. There are many numerical models for TCs that are witnessing continuing improvements, where the decay characteristics after landfall are explained as a combined effect of atmospheric circumstances and TCs' own properties (e.g., GFDL hurricane model, NOAA) as well as influences of topography, specifically mountain ranges (Bender et al 1987).…”

“…Ramsay and Leslie (2008) applied the Pennsylvania State University -National Center for Atmospheric Research mesoscale numerical model (MM5) to TC Larry in Australia to assess the influence of coastal orography. However, the level of sophistication required in numerical models for a TC's intensity and track predictions after landfall with acceptable reliability is still beyond human reach (Roy Bhowmik et al 2005), and the need for useful empirical models exists. According to Done et al (2015) TCs continue to remain a hard test case for numerical modelling.…”