# Acoustics Monitoring Program: Upsweep > Acoustics Program NOAA Pacific Marine Environmental Laboratory, n.d.. 15 records on Mysteries Department cite it. The primary record of the one sound… Source: https://mysteriesdept.com/sources/SRC0D9C712R2AJY/acoustics-monitoring-program-upsweep Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) --- [Sources](https://mysteriesdept.com/sources)[Bloop and NOAA's unexplained ocean sounds](https://mysteriesdept.com/mysteries/noaa-ocean-sounds)NOAA Pacific Marine Environmental Laboratory n.d. **0** # Acoustics Monitoring Program: Upsweep Acoustics Program NOAA Pacific Marine Environmental Laboratory, n.d.. _NOAA PMEL Acoustics Program (pmel.noaa.gov)_. Describes the Upsweep: present when PMEL began recording SOSUS in August 1991; a long train of narrowband upsweeping sounds of several seconds each; loud enough to be heard across the Pacific; seasonal, peaking in spring and autumn; roughly located at 54°S 140°W near inferred volcanic seismicity; origin unresolved; declining in level since 1991 but still detected on the equatorial arrays. **Bloop and NOAA's unexplained ocean sounds** Web pageCopy of **[The Upsweep recording](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/artifacts/ART0D9C7TF8459E/the-upsweep-recording)** Checked against the original0 ## What it's used for here The primary record of the one sound PMEL still lists as unresolved. ## Cited by on this site 15 records [The source is steady and the seasonality is an artefact of seasonal changes in how sound travels from it.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/answers/ANS0D9C7NK03Z2B/the-source-is-steady-and-the-seasonality-is-an-artefact-of) Answer ANS [Upsweep is produced by an undersea volcanic or hydrothermal source near 54°S 140°W.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/answers/ANS0D9C7KMG1Y78/upsweep-is-produced-by-an-undersea-volcanic-or-hydrothermal) Answer ANS [The Upsweep recording](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/artifacts/ART0D9C7TF8459E/the-upsweep-recording) ART [The Upsweep recording: audio](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/copies/CPY0D9C7TQ22VKB/the-upsweep-recording-audio) CPY [The Upsweep recording: document](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/copies/CPY0D9C7TYW1RV3/the-upsweep-recording-document) CPY [NOAA assigns four of the six sounds to ice and one to a volcano; Upsweep remains unresolved.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7EGE4BDY/noaa-assigns-four-of-the-six-sounds-to-ice-and-one-to-a) Evidence EVD [PMEL names seasonal propagation as one possible cause of the seasonality.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7NTT0TJ2/pmel-names-seasonal-propagation-as-one-possible-cause-of-the) Evidence EVD [PMEL states that the origin is unresolved.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7MBY03JQ/pmel-states-that-the-origin-is-unresolved) Evidence EVD [The rough location lies near inferred volcanic seismicity.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7KWA5SQR/the-rough-location-lies-near-inferred-volcanic-seismicity) Evidence EVD [Upsweep is narrowband and regular, unlike broadband icequakes.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7NB60VFT/upsweep-is-narrowband-and-regular-unlike-broadband-icequakes) Evidence EVD [Upsweep peaks in spring and autumn, which may reflect either the source or seasonal propagation.](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/evidence/EVD0D9C7N3C1XRY/upsweep-peaks-in-spring-and-autumn-which-may-reflect-either) Evidence EVD [PMEL begins recording the Navy's SOSUS arrays; Upsweep is already present](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/events/EVT0D9C79CC48BJ/pmel-begins-recording-the-navys-sosus-arrays-upsweep-is) EVT [The Bloop and NOAA's unexplained ocean sounds](https://mysteriesdept.com/mysteries/noaa-ocean-sounds) The mystery article MYS [What made the loud unidentified sounds recorded by NOAA's Pacific hydrophones in the 1990s?](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/questions/QST0D9C7CA41BJB/what-made-the-loud-unidentified-sounds-recorded-by-noaas) Question QST [What produces the Upsweep?](https://mysteriesdept.com/mysteries/noaa-ocean-sounds/questions/QST0D9C7CSR0G1Y/what-produces-the-upsweep) Question QST ## Cite it ``` NOAA Pacific Marine Environmental Laboratory, A. P. (n.d.). Acoustics Monitoring Program: Upsweep. NOAA PMEL Acoustics Program (pmel.noaa.gov). https://www.pmel.noaa.gov/acoustics/sounds/upsweep.html ``` [Read it free at pmel.noaa.gov](https://www.pmel.noaa.gov/acoustics/sounds/upsweep.html) Key **SRC** 0D9C712R2AJY Kind Web page Rights public-domain Kept 29 Oct 2026 Checked Against the published original Added by [apollo](https://mysteriesdept.com/u/apollo) The record Bibliographic records are CC0. Take this one as CSL-JSON, BibTeX or RIS. [CSL-JSON](https://mysteriesdept.com/sources/SRC0D9C712R2AJY/acoustics-monitoring-program-upsweep/csl.json)