APL-UW Home

Jobs
About
Campus Map
Contact
Privacy
Intranet

Rex Andrew

Principal Engineer

Email

rex@apl.washington.edu

Phone

206-543-1250

Biosketch

Rex Andrew's research interests involve the use of acoustic signals to infer the properties of the source mechanism itself or the medium through which the signals propagate. In the ocean, this field is commonly known as acoustical oceanography. This discipline requires the combination of statistical signal and array processing theory with the physics of wave propagation for proper interpretation.

Department Affiliation

Acoustics

Education

B.S. Physics, University of Washington, 1981

M.S. Electrical Engineering, University of Washington, 1987

Ph.D. Electrical and Computer Engineering, University of Victoria, 1999

Publications

2000-present and while at APL-UW

Year-round acoustic monitoring of Antarctic blue and fin whales in relation to environmental conditions off the west coast of South Africa

Letsheleha, I.S., F.W. Shabangu, D. Farrell, R.K. Andrew, P.L. la Grange, and K.P. Findlay, "Year-round acoustic monitoring of Antarctic blue and fin whales in relation to environmental conditions off the west coast of South Africa," Mar. Biol., 169, doi:10.1007/s00227-022-04026-x, 2022.

More Info

25 Feb 2022

Antarctic blue and fin whales were once abundant in the southeastern Atlantic Ocean, yet their occurrence and ecology in this region is still poorly understood. Seasonal acoustic occurrence and behaviour of Antarctic blue and fin whales off the South African west coast were determined using bio-acoustic data collected through two autonomous acoustic recorders between December 2015 and January 2017. Blue whale Z-calls were detected year-round with a peak in July, while fin whale 20 Hz pulses were detected seasonally with a peak in June by a recorder deployed at 1118 m water depth. Blue and fin whale calls were detected seasonally with a similar peak in May by a recorder deployed at 4481 m water depth. The blue whale 27 Hz chorus, and blue and fin whale 18-28 Hz chorus followed a similar trend as the seasonal acoustic occurrence of individual Z-calls and 20 Hz pulses. A maximum detection range of 800 km estimated by acoustic propagation modelling suggests that detected calls originate from whales within the South African west coast waters. Random forest models classified month of the year, wind speed, log-transformed chlorophyll-a, and sea surface temperature anomaly as the most important predictors of blue and fin whale acoustic occurrence and behaviour. Our study highlights the South African west coast as an important year-round habitat and seasonal breeding or overwintering habitat of these whales. Additionally, the year-round acoustic occurrence in this region supports the notion that blue whale migration patterns are more dynamic than previously perceived.

Acoustic occurrence, diel-vocalizing pattern, and detection ranges of southern right whale gunshot sounds off South Africa's west coast

Shabangu, F.W., R.K. Andrew, and K. Findlay, "Acoustic occurrence, diel-vocalizing pattern, and detection ranges of southern right whale gunshot sounds off South Africa's west coast," Mar. Mammal Sci., 37, 733-750, doi:10.1111/mms.12760, 2021.

1 Apr 2021

Temperature-driven seasonal and longer term changes in spatially averaged deep ocean ambient sound at frequencies 63–125 Hz

Ainslie, M.A., R.K. Andrew, B.M. Howe, and J.A. Mercer, "Temperature-driven seasonal and longer term changes in spatially averaged deep ocean ambient sound at frequencies 63–125 Hz," J. Acoust. Soc. Am., 149, 2531-2545, doi:10.1121/10.0003960, 2021.

More Info

1 Apr 2021

The soundscape of the Northeast Pacific Ocean is studied with emphasis on frequencies in the range 63–125 Hz. A 34-year (1964–1998) increase and seasonal fluctuations (1994–2006) are investigated. This is achieved by developing a simple relationship between the total radiated power of all ocean sound sources and the spatially averaged mean-square sound pressure in terms of the average source factor, source depth, and sea surface temperature (SST). The formula so derived is used to predict fluctuations in the sound level in the range 63–125 Hz with an amplitude of 1.2 dB and a period of 1 year associated with seasonal variations in the SST, which controls the amount of sound energy trapped in the sound fixing and ranging (SOFAR) channel. Also investigated is an observed 5 dB increase in the same frequency range in the Northeast Pacific Ocean during the late 20th century [Andrew, Howe, Mercer, and Dzieciuch (2002). ARLO 3, 65–70]. The increase is explained by the increase in the total number of ocean-going ships and their average gross tonnage.

More Publications

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
Close

 

Close