Susan D. Gardner
Roger W. Meredith
Code 242, NRL/DET, Stennis Space Center, MS 39529-5004
NRL/SSC conducted Arctic acoustics experiments in the Beaufort Sea as part
of ICEX-92 in March and April of 1992. One objective was to collect a long-term
time series of low-frequency (less than 50-Hz) acoustic ambient noise with a
volumetric array to investigate environmental forcing functions and 3-D noise
characteristics. A total of 191 nearly continuous hours of acoustic ambient
noise was collected with a vertical array and three horizontal line arrays that
were separated approximately 60(degrees) in azimuth. A geophone array was also
deployed coincident with one of the horizontal line arrays. Meterological data
collected included wind speed, wind direction, temperature, and barometric
pressure. Oceanographic data included CTD's and current velocities. Local
environmental conditions varied widely during the data collection period. In
addition, both ridging and an opening of the ice occurred within 500 ft of the
vertical array during data collection. The focus of this presentation is the
first step in the analysis of this data set and examines the relationship
between ambient noise level fluctuations observed on an individual hydrophone
and changes in local air temperature for different time scales. Gradual surface
temperature increases and decreases over 10-h time segments occur simultaneous
with an increase in the noise fluctuation. Temperature changes during time
periods less than 5 h show minimal effect on noise fluctuations. Geophone data
agree well with acoustic data in both level and fluctuation. Comparisons of
ambient noise with other local forcing functions will be discussed. [This
research was supported by ASW Environmental Acoustics Support Program (AEAS).]