Effect of extreme ocean precipitation on sea surface elevation and storm surges. (27th July 2016)

• Record Type: Journal Article
• Authors: Wong, Benjamin; Toumi, Ralf
• Is Part Of: Quarterly journal of the Royal Meteorological Society. Volume 142:Number 699(2016)
• Page Start: 2541
• Page End: 2550
• Publication Date: 2016-07-27
• Subjects: ocean modelling -- cyclone Monica -- rain mass -- rain stress; Meteorology -- Periodicals; 551.5
• DOI: 10.1002/qj.2845
• Languages: English
• ISSNs: 0035-9009

Abstract

Abstract : Ocean models that neglect mass and momentum contributions from precipitation can have a systematic bias in sea surface height (SSH). Here, a new rainfall scheme is introduced into the Regional Ocean Modelling System (ROMS) to incorporate the effects of precipitation mass. When precipitation is added to the sea surface, it spreads out via surface gravity waves that increase in propagation speed with increasing water depth. Over several days, the SSH increase due to the precipitation mass added creates a geostrophic adjustment, generating anticyclonic geostrophic currents around the SSH increase. The transfer of momentum from precipitation to the sea surface, or rain stress, can also be important. In the case‐study of a real tropical cyclone, Monica, passing North Australia, the effect of incorporating precipitation mass is compared with other processes affecting the storm surge: surface wind, inverse barometer effect and rain stress. The maximum SSH response is 170.6 cm for the wind effect, 61.5 cm for the inverse barometer effect, 7.5 cm for the effect of rain stress and 6.4 cm for the effect of rain mass. Each process has been shown to have different spatial influences. The effect of rain mass has a strong remote influence compared to the inverse barometer effect and the effect of rain stress. This is particularly seen in semi‐enclosed bays.