Underwater Acoustic Measurements to Estimate Wind and Rainfall in the Mediterranean Sea

Abstract

Oceanic ambient noise measurements can be analyzed to obtain qualitative and quantitative information about wind and rainfall phenomena over the ocean filling the existing gap of reliable meteorological observations at sea. The Ligurian Sea Acoustic Experiment was designed to collect long-term synergistic observations from a passive acoustic recorder and surface sensors (i.e., buoy mounted rain gauge and anemometer and weather radar) to support error analysis of rainfall rate and wind speed quantification techniques developed in past studies. The study period included combination of high and low wind and rainfall episodes and two storm events that caused two floods in the vicinity of La Spezia and in the city of Genoa in 2011. The availability of high resolution in situ meteorological data allows improving data processing technique to detect and especially to provide effective estimates of wind and rainfall at sea. Results show a very good correspondence between estimates provided by passive acoustic recorder algorithm and in situ observations for both rainfall and wind phenomena and demonstrate the potential of using measurements provided by passive acoustic instruments in open sea for early warning of approaching coastal storms, which for the Mediterranean coastal areas constitutes one of the main causes of recurrent floods.

Precipitation measurements from the Tropical Moored Array: A review and look ahead

“…A new rain rate algorithm introduced by Pensieri et al . () using coefficients derived from the Vaisala WXT510 acoustic rain‐gauge mounted on the buoy mast above the surface showed improved comparisons with radar for observations over the Mediterranean Sea. In addition to training the formulation for the PAL on local rainfall data, Pensieri et al .…”

“…In addition to training the formulation for the PAL on local rainfall data, Pensieri et al . () used two sets of coefficients, one for drizzle and one for medium to heavy rain.…”

“…Early versions of these sensors have been tested at selected TMA sites between late 1999 and early 2002 with encouraging results (Ma and Nystuen, 2005). More recently, PALs have been deployed in the Ionian Sea (Anagnostou et al, 2008), Mediterranean Sea (Pensieri et al, 2015) and on the NOAA Ocean Climate Station (OCS) Papa in the North Pacific (Yang et al, 2015). Comparing six years of rainfall observations from the PAL to those from the PMEL capacitance gauge at OCS Papa, good agreement is seen both in terms of the frequency and magnitude of events (Yang et al, 2015).…”

“…As the PALs tended to overestimate rainfall compared to the radar, wind-biased parameters cannot explain the observed bias. A new rain rate algorithm introduced by Pensieri et al (2015) using coefficients derived from the Vaisala WXT510 acoustic rain-gauge mounted on the buoy mast above the surface showed improved comparisons with radar for observations over the Mediterranean Sea. In addition to training the formulation for the PAL on local rainfall data, Pensieri et al (2015) used two sets of coefficients, one for drizzle and one for medium to heavy rain.…”

Analysis of the Precipitation Regime over the Ligurian Sea

“…The sensor is also capable of distinguishing hailstones from raindrops and it was designed to be immune to flooding clogging, wetting and evaporation losses during rain measurements. This type of instrument was successfully employed to obtain reliable rainfall observations on both land and at sea [25][26][27][28]. The instrument is mounted on the central mast of the buoy about 12 m above the mean sea level.…”