Regional Rainfall Measurements Using Passive Aquatic Listener During SPURS Field Campaign
[12-Nov-2014] Yang, J., Riser, S., Nystuen, J., Asher, W., and Jessup, A.
Presented at the 2014 Aquarius/SAC-D Science Team Meeting
Knowledge of the intensity and spatial-temporal distribution of rainfall over the ocean is critical in understanding the global hydrological cycle. However, rain has proven to be difficult to measure over the ocean due to problems associated with deploying rain sensors from moving platforms combined with the spatial and temporal variability of rainfall itself. Underwater acoustical rain gauges avoid the issues of surface rain sensors by using the loud and distinctive underwater sound generated by raindrops on the ocean surface to detect and quantify rainfall. Here, the physics, operation, and results from an instrument that uses underwater ambient sound to measure rainfall rate and wind speed are presented. Passive Aquatic Listener (PAL) instruments were mounted on a buoy deployed at Ocean Station P and on sixteen Argo profilers that were deployed as part of the NASA-sponsored Salinity Processes in the Upper ocean Regional Studies (SPURS) field experiment in the North Atlantic Ocean. The PALs provide near-continuous measurements of rain rate and wind speed over the two-year period over the SPURS study region defined by the Argo profilers. Comparisons of the PAL data with rain and wind measured by other techniques including direct in situ observations and satellite measurements show good agreement for both rain rate and wind speed.