On the Rapid Ocean Response to High-Frequency Intense Rainfall
[28-Aug-2018] Clarke, A.J. and Zhang, X.
Presented at the 2018 Ocean Salinity Science Team and Salinity Continuity Processing Meeting
If intense rain falls uniformly at a rate of 50mm/hour over a circular lake of radius a, and there is no evaporation, then after 1 hour the sea level would rise by 5cm. But how is the sea level rise distributed over a similar circular region if the rain falls over the open ocean? Analytical results for this idealized rainfall with rate R provide physical insight about how the size of the ocean response depends on the rainfall rate, its duration, and its horizontal scale. Since the extra mass of the freshwater flux is felt throughout the water column, we expect the ocean response to be barotropic and be in the form of long gravity waves propagating at a speed c equal to about 200m/s. A crucial parameter is ωa/c
, the ratio of the time a/c it takes the wave to cross the rainfall spatial scale a compared to the time scale ω-1
of the forcing. In this presentation we check the theoretical predictions of the ocean response using Deep-ocean Assessment and Reporting of Tsunamis (DART) bottom pressure data, TAO-TRITON buoy salinity and rainfall data, and the Integrated Multi-satellite Retrievals for Global precipitation measurement (IMERG) rainfall data.