This is a short tutorial on how I process and analyze passive acoustic data from autonomous underwater recorders that are moored in the ocean for up to several years. I am interested in analyzing how the ambient sound varies with time and location, and how loud the “choruses” of different marine mammal of vocalizations are over time. To achieve this I am simply simply calculating the power spectral density (PSD) over a 5 minute time period, so that I get one spectrum per recording. But lets start at the beginning.
We were all supposed to avoid crowds in 2020, meaning the safest place to climb would be new routes right? Following this logic, we climbed a couple new routs last season. The most noteworthy of these has been a 6 pitch route following a systems of dihedrals up a west-facing slab near Evanger (Between Bergen and Voss). We also found, cleaned and sent a fun offwidth crack on Sotra and some short seascliff crack lines. Here are the best bits:
The weather in western Norway is usually wet and variable, where long cold spells are rare. But if they occur, the fjords and valleys turn from moist choss piles into the Yosemite of iceclimbing, with beautiful lines around every corner. January and February 2021 were blessed with a long cold spell of up to -20 degrees at sea level and almost no precipitation for several weeks. While that made for bad skiing, for iceclimbers it was like Christmas and easter on the same date.
This document will guide you through the steps necessary to process and analyse both vessel mounted (VM-ADCP) and lowered acoustic doppler current profilers (L-ADCP). Both are complex data sources that contain a lot of noise and potential biases, but dont despair, with todays programms and code packages anyone can work with this data and produce meaningfull results.