CASE STUDY

Typhoon Over South China Sea

With the onset of Super Typhoon Mangkhut on 7 September 2018 potentially one of the strongest storms to hit Hong Kong till date sweeps across east Asia and Hurricane Florence, threatened the east coast of the United States.Scientists have repeatedly emphasized that rising temperatures could mean that such mega-storms will become more common in future.

AS OCEAN TEMPERATURES RISE WITH GLOBAL WARMING, THE TROPICAL CYCLONES THAT THREATEN BOTH EAST ASIA AND THE ATLANTIC SEABOARD COULD GROW IN STRENGTH AND INTENSITY.

SOUTH CHINA SEA TYPHOONS AND INTER-SEASONAL VARIABILITY

Approximately one-third of all tropical cyclones originate over the western half of the North Pacific Ocean, making it the most prolific of the tropical cyclone basins. The majority of North Pacific tropical cyclones (and the majority that reach typhoon intensity) occur during June−October. Previous work on the climatology of western North Pacific typhoons has focused on variations in annual frequency. Studies show that the El Niño/Southern Oscillation (ENSO) plays a role in the frequency and distribution of western North Pacific typhoons. While the effect of ENSO on the overall number of typhoons appears to be minor, it tends to create conditions favourable for shifts in the main genesis region.

TRENDS OF TRACKS OF THE TYPHOONS OVER THE SOUTH CHINA SEA

On average, straight-moving typhoons form farther south and west of the recurving typhoons, partly due to the fact that a subset of the straight-moving typhoons forms over the South China Sea, west of the Philippines. The latitudinal separation between the first and last positions for straight moving typhoons is less than 5° on average. This compares with more than 11° on average for both recurving and north-oriented typhoons. The average maximum intensity of straight-moving typhoons is less than that for recurving typhoons, whereas the average time at typhoon intensity is shortest for the straight-moving typhoons because they reach the coast quicker (and thus weaken quicker). These two facts are related, as the group of straight-moving typhoons includes the shorter-lived tropical cyclones of the South China Sea.

(Source: Li C (1986) El Nino and typhoon action over the western Pacific. KexueTongbao 31:538–542)

INTENSEL’S TYPHOON MODELLING OVER THE SOUTH CHINA SEA

AS OCEAN TEMPERATURES RISE, RELATIVE TO EXISTING SOLUTIONS, OUR MODEL HAS MORE DETAILS COMPARED TO SATELLITE DATA, 50X BETTER TEMPORAL RESOLUTION AND 20+MORE VARIABLES.

Source: Modelling Capability: Simulation for Hato Typhoon at 4 km Resolution

Source: Best available observed data (top) & Our modelled data (bottom)