Tanya Maurer

Subantarctic pCO2 estimated from a biogeochemical float: comparison with moored observations reinforces the importance of spatial and temporal variability

Publisher: Frontiers Media SA

Date: 25-07-2023

DOI: 10.3389/FMARS.2023.1231953

Abstract: Understanding the size and future changes of natural ocean carbon sinks is critical for the projection of atmospheric CO 2 levels. The magnitude of the Southern Ocean carbon flux has varied significantly over past decades but mechanisms behind this variability are still under debate. While high accuracy observations, e.g. from ships and moored platforms, are important to improve models they are limited through space and time. Observations from autonomous platforms with emerging biogeochemical capabilities, e.g. profiling floats, provide greater spatial and temporal coverage. However, the absolute accuracy of CO 2 partial pressure ( p CO 2 ) derived from float pH sensors is not well constrained. Here we capitalize on data collected for over a year by a biogeochemical Argo float near the Southern Ocean Time Series observatory to evaluate the accuracy of p CO 2 estimates from floats beyond the initial in water comparisons at deployment. A latitudinal gradient of increasing p CO 2 southward and spatial variability contributed to observed discrepancies. Comparisons between float estimated p CO 2 and mooring observations were therefore restricted by temperature and potential density criteria (~ 7 µatm difference) and distance (1° latitude and longitude, ~ 11 µatm difference). By utilizing high quality moored and shipboard underway p CO 2 observations, and estimates from CTD casts, we therefore found that over a year, differences in p CO 2 between platforms were within tolerable uncertainties. Continued validation efforts, using measurements with known and sufficient accuracy, are vital in the continued assessment of float-based p CO 2 estimates, especially in a highly dynamic region such as the subantarctic zone of the Southern Ocean.

Real-time quality control of optical backscattering data from Biogeochemical-Argo floats

Publisher: F1000 Research Ltd

Date: 30-05-2023

DOI: 10.12688/OPENRESEUROPE.15047.2

Abstract: Background: Biogeochemical-Argo floats are collecting an unprecedented number of profiles of optical backscattering measurements in the global ocean. Backscattering (BBP) data are crucial to understanding ocean particle dynamics and the biological carbon pump. Yet, so far, no procedures have been agreed upon to quality control BBP data in real time. Methods: Here, we present a new suite of real-time quality-control tests and apply them to the current global BBP Argo dataset. The tests were developed by expert BBP users and Argo data managers and have been implemented on a snapshot of the entire Argo dataset. Results: The new tests are able to automatically flag most of the “bad” BBP profiles from the raw dataset. Conclusions: The proposed tests have been approved by the Biogeochemical-Argo Data Management Team and will be implemented by the Argo Data Assembly Centres to deliver real-time quality-controlled profiles of optical backscattering. Provided they reach a pressure of about 1000 dbar, these tests could also be applied to BBP profiles collected by other platforms.

Multilevel selection 1, multilevel selection 2, and the Price equation: a reappraisal

Publisher: Springer Science and Business Media LLC

Date: 24-08-2023

DOI: 10.1007/S11229-023-04285-1

Abstract: The distinction between multilevel selection 1 (MLS1) and multilevel selection 2 (MLS2) is classically regarded as a distinction between two multilevel selection processes involving two different kinds of higher-level fitness. It has been invoked to explain evolutionary transitions in in iduality as a shift from an MLS1 to an MLS2 process. In this paper, I argue against the view that the distinction involves two different kinds of processes. I show, starting from the MLS2 version of the Price equation, that it contains the MLS1 version if, following the assumption that a collective constitutively depends (i.e., mereologically supervenes) on its particles, one considers that a necessary map between fitness at two levels exists. I defend the necessity of such a map, making the distinction between MLS1 and MLS2 a matter of perspective and limited knowledge (i.e., epistemic limitations) rather than objective facts. I then provide some reasons why the MLS1/MLS2 distinction nonetheless has some pragmatic value and might be invoked usefully in some contexts, particularly within the context of explaining evolutionary transitions in in iduality.

Real-time quality control of optical backscattering data from Biogeochemical-Argo floats

Publisher: F1000 Research Ltd

Date: 13-10-2022

DOI: 10.12688/OPENRESEUROPE.15047.1

Abstract: Background: Biogeochemical-Argo floats are collecting an unprecedented number of profiles of optical backscattering measurements in the global ocean. Backscattering (BBP) data are crucial to understanding ocean particle dynamics and the biological carbon pump. Yet, so far, no procedures have been agreed upon to quality control BBP data in real time. Methods: Here, we present a new suite of real-time quality-control tests and apply them to the current global BBP Argo dataset. The tests were developed by expert BBP users and Argo data managers and have been implemented on a snapshot of the entire Argo dataset. Results: The new tests are able to automatically flag most of the “bad” BBP profiles from the raw dataset. Conclusions: The proposed tests have been approved by the Biogeochemical-Argo Data Management Team and will be implemented by the Argo Data Assembly Centres to deliver real-time quality-controlled profiles of optical backscattering. Provided they reach a pressure of about 1000 dbar, these tests could also be applied to BBP profiles collected by other platforms.

Monterey Bay Aquarium Research Institute

Location: United States of America

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Linkage Projects - Grant ID: LP0776400

Start Date: 07-2007

End Date: 12-2013

Amount: $228,868.00

Funder: Australian Research Council