[AOS24-P17] Seasonal dynamics of zooplankton at station K2, NW Pacific, reconstructed from archived ADCP data
Keywords:zooplankton, acoustic backscattering , western subarctic North Pacific
Sv = C + 10log10((Tx+ 273.16) x R2) – LDBM– PDBM+ 2αR +Kc(E –Er)
where C is an empirical constant, Tx is the temperature of the transducer, R is the range along the beam to the scatterers, LDBM is the transmit pulse length, PDBM is the transmit power, α is the absorption coefficient, Kc is a conversion factor for eco intensity from counts to dB, E is the echo intensity in counts, and Er is the reference echo intensity which was taken as the instrument-specific lowest measured value over the mooring period. Although we could not obtain the acoustic data between sea surface and ca 30 m in depth due to side lobe effect of sound, four years time-series of backscattering strengths between 30 and 350 m was successfully collected. In the poster, we will describe seasonal variability and diel change of acoustic backscattering strength at K2. During the summer of 2016, strong current velocity was observed and the moored ADCP sank down to 660 m in depth. We will also discuss zooplankton dynamics during the event.