The impact of sea-level rise on tidal characteristics around Australia

An established tidal model, validated for present-day conditions, is used to investigate the effect of large levels of sea-level rise (SLR) on tidal characteristics around Australasia. SLR is implemented through a uniform depth increase across the model domain, with a comparison between the implementation of coastal defences or allowing low-lying land to flood. The complex spatial response of the semi-diurnal M2 constituent does not appear to be linear with the imposed SLR. The most predominant features of this response are the generation of new amphidromic systems within the Gulf of Carpentaria and large-amplitude changes in the Arafura Sea, to the north of Australia, and within embayments along Australia's north-west coast. Dissipation from M2 notably decreases along north-west Australia but is enhanced around New Zealand and the island chains to the north. The diurnal constituent, K1, is found to decrease in amplitude in the Gulf of Carpentaria when flooding is allowed. Coastal flooding has a profound impact on the response of tidal amplitudes to SLR by creating local regions of increased tidal dissipation and altering the coastal topography. Our results also highlight the necessity for regional models to use correct open boundary conditions reflecting the global tidal changes in response to SLR.</p

Low-frequency dynamic ocean response to barometric-pressure loading

Author Posting. © American Meteorological Society, 2022. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 52(11), (2022): 2627-2641, https://doi.org/10.1175/jpo-d-22-0090.1.Changes in dynamic manometric sea level ζm represent mass-related sea level changes associated with ocean circulation and climate. We use twin model experiments to quantify magnitudes and spatiotemporal scales of ζm variability caused by barometric pressure pa loading at long periods (≳1 month) and large scales (≳300km) relevant to Gravity Recovery and Climate Experiment (GRACE) ocean data. Loading by pa drives basin-scale monthly ζm variability with magnitudes as large as a few centimeters. Largest ζm signals occur over abyssal plains, on the shelf, and in marginal seas. Correlation patterns of modeled ζm are determined by continental coasts and H/f contours (H is ocean depth and f is Coriolis parameter). On average, ζm signals forced by pa represent departures of ≲10% and ≲1% from the inverted-barometer effect ζib on monthly and annual periods, respectively. Basic magnitudes, spatial patterns, and spectral behaviors of ζm from the model are consistent with scaling arguments from barotropic potential vorticity conservation. We also compare ζm from the model driven by pa to ζm from GRACE observations. Modeled and observed ζm are significantly correlated across parts of the tropical and extratropical oceans, on shelf and slope regions, and in marginal seas. Ratios of modeled to observed ζm magnitudes are as large as ∼0.2 (largest in the Arctic Ocean) and qualitatively agree with analytical theory for the gain of the transfer function between ζm forced by pa and wind stress. Results demonstrate that pa loading is a secondary but nevertheless important contributor to monthly mass variability from GRACE over the ocean.The authors acknowledge support from the National Aeronautics and Space Administration through the GRACE Follow-On Science Team (Grant 80NSSC20K0728) and the Sea Level Change Team (Grant 80NSSC20K1241). The contribution from I. F. and O. W. represents research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (Grant 80NM0018D0004)

Report of the IAU/IAG Joint Working Group on Theory of Earth Rotation and Validation

This report focuses on some selected scientific outcomes of the activities developed by the IAU/IAG Joint Working Group on Theory of Earth rotation and validation along the term 2015–2019. It is based on its end-of-term report to the IAG Commission 3 published in the Travaux de l’IAG 2015–2019, which in its turn updates previous reports to the IAG and IAU, particularly the triennial report 2015–2018 to the IAU Commission A2, and the medium term report to the IAG Commission 3 (2015–2017). The content of the report has served as a basis for the IAG General Assembly to adopt Resolution 5 on Improvement of Earth rotation theories and models.JMF, AE, and JG were partially supported by Spanish Project AYA2016-79775-P (AEI/FEDER, UE). The work of RSG described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Support for that work was provided by the Earth Surface and Interior Focus Area of NASA’s Science Mission Directorate

Are Ocean Reanalyses Useful for Earth Rotation Research?

Oceanic circulation and mass‐field variability play important roles in exciting Earth's wobbles and length‐of‐day changes (ΔΛ), on time scales from days to several years. Modern descriptions of these effects employ oceanic angular momentum (OAM) series from numerical forward models or ocean state estimates, but nothing is known about how ocean reanalyses with sequential data assimilation (DA) would fare in that context. Here, we compute daily OAM series from three 1/4° global ocean reanalyses that are based on the same hydrodynamic core and input data (e.g., altimetry, Argo) but different DA schemes. Comparisons are carried out (a) among the reanalyses, (b) with an established ocean state estimate, and (c) with Earth rotation data, all focusing on the period 2006–2015. The reanalyses generally provide credible OAM estimates across a range of frequencies, although differences in amplitude spectra indicate a sensitivity to the adopted DA scheme. For periods less than 120 days, the reanalysis‐based OAM series explain ∼40%–50% and ∼30%–40% of the atmosphere‐corrected equatorial and axial geodetic excitation, similar to what is achieved with the state estimate. We find mixed performance of the reanalyses in seasonal excitation budgets, with some questionable mean ocean mass changes affecting the annual cycle in ΔΛ. Modeled excitations at interannual frequencies are more uncertain compared to OAM series from the state estimate and show hints of DA artifacts in one case. If users are to choose any of the tested reanalyses for rotation research, our study points to the Ocean Reanalysis System 5 as the most sensible choice.Key Points: We evaluate three ocean reanalyses for their skill in explaining Earth rotation variations on different time scales from 2006 to 2015. For periods <120 days, reanalyses explain 40%–50% of atmosphere‐reduced polar motion excitation variance, similar to an ocean state estimate. Reanalyses show mixed skill in seasonal excitation budgets and, in one case, hints of data assimilation artifacts at interannual periods.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659https://resources.marine.copernicus.eu/product-detail/GLOBAL_REANALYSIS_PHY_001_031/INFORMATIONhttps://isdc.gfz-potsdam.de/ggfc-oceans/oam/https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ngdc.mgg.dem:316https://podaac-tools.jpl.nasa.gov/drive/files/GeodeticsGravity/tellus/L3/mascon/RL06/JPL/v02/CRI/netcdfhttps://keof.jpl.nasa.gov/combinations

Are Ocean Reanalyses Useful for Earth Rotation Research?

Abstract Oceanic circulation and mass‐field variability play important roles in exciting Earth's wobbles and length‐of‐day changes (ΔΛ), on time scales from days to several years. Modern descriptions of these effects employ oceanic angular momentum (OAM) series from numerical forward models or ocean state estimates, but nothing is known about how ocean reanalyses with sequential data assimilation (DA) would fare in that context. Here, we compute daily OAM series from three 1/4° global ocean reanalyses that are based on the same hydrodynamic core and input data (e.g., altimetry, Argo) but different DA schemes. Comparisons are carried out (a) among the reanalyses, (b) with an established ocean state estimate, and (c) with Earth rotation data, all focusing on the period 2006–2015. The reanalyses generally provide credible OAM estimates across a range of frequencies, although differences in amplitude spectra indicate a sensitivity to the adopted DA scheme. For periods less than 120 days, the reanalysis‐based OAM series explain ∼40%–50% and ∼30%–40% of the atmosphere‐corrected equatorial and axial geodetic excitation, similar to what is achieved with the state estimate. We find mixed performance of the reanalyses in seasonal excitation budgets, with some questionable mean ocean mass changes affecting the annual cycle in ΔΛ. Modeled excitations at interannual frequencies are more uncertain compared to OAM series from the state estimate and show hints of DA artifacts in one case. If users are to choose any of the tested reanalyses for rotation research, our study points to the Ocean Reanalysis System 5 as the most sensible choice

Modeling ocean-induced rapid Earth rotation variations: an update

We revisit the problem of modeling the ocean’s contribution to rapid, non-tidal Earth rotation variations at periods of 2–120 days. Estimates of oceanic angular momentum (OAM, 2007–2011) are drawn from a suite of established circulation models and new numerical simulations, whose finest configuration is on a 1⁄ 6◦ grid. We show that the OAM product by the Earth System Modeling Group at GeoForschungsZentrum Potsdam has spurious short period variance in its equatorial motion terms, rendering the series a poor choice for describing oceanic signals in polar motion on time scales of less than ∼2 weeks. Accounting for OAM in rotation budgets from other models typically reduces the variance of atmosphere-corrected geodetic excitation by ∼54% for deconvolved polar motion and by ∼60% for length-of-day. Use of OAM from the 1⁄ 6◦ model does provide for an additional reduction in residual variance such that the combined oceanic–atmospheric effect explains as much as 84% of the polar motion excitation at periods < 120 days. Employing statistical analysis and bottom pressure changes from daily Gravity Recovery and Climate Experiment solutions, we highlight the tendency of ocean models run at a 1◦ grid spacing to misrepresent topographically constrained dynamics in some deep basins of the Southern Ocean, which has adverse effects on OAM estimates taken along the 90◦ meridian. Higher model resolution thus emerges as a sensible target for improving the oceanic component in broader efforts of Earth system modeling for geodetic purposes.Austrian Science Fund http://dx.doi.org/10.13039/501100002428National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104https://isdc.gfz-potsdam.de/ggfc-oceans/https://doi.org/10.5281/zenodo.4707150http://rz-vm115.gfz-potsdam.de:8080/repository/https://ifg.tugraz.at/ITSG-Grace2018ftp://isdcftp.gfz-potsdam.de/grace/Level-1B/GFZ/AOD/RL06/https://ecco-group.org/products-ECCO-V4r4.ht

Late Pleistocene evolution of tides and tidal dissipation: dissipation data

These .mat files contain the dissipation files calculated in Wilmes et al. (2023) Late Pleistocene evolution of tides and tidal dissipation. For details on how dissipation was calculated and the simulation details see the paper. Each file contains following variables: time_(i or g) = time in ka BP lat & lon = latitude and longitude vectors const = tidal constituents (M2, S2, K1, O1) diss_all = dissipation time slices for all runs (33 for Gowan, 62 for ICE-6G); dimensions: lon/lat/time/const mz_all = land mask time slices for all runs; dimensions: lon/lat/time hz_all = bathymetries time slices for all runs; dimensions: lon/lat/time dtot_all / dshelf_all/ ddeep_all = globally integrated dissipation values for all time slices for global dissipation / open dissipation / shelf dissipation; dimensions: time/cons

The Anomalous 2012–13 Boreal Winter Oceanic Excitation of Earth’s Polar Motion

International audienc

Win–win for everyone? Reflecting on nature-based solutions for flood risk management from an environmental justice perspective

Nature-based solutions (NbS) are often framed positively in terms of win–win options or no-regret measures. However, are NbS equally beneficial for everyone? Are burdens and benefits of NbS really equally distributed and projects embraced by everyone? Is the process leading to the implementation of NbS always fair and inclusive? This chapter provides a broad overview of different environmental justice issues, critically reflecting on NbS through recognition justice, procedural justice, and distributive justice. Whereas the current critical literature focuses particularly on urban NbS, this chapter focuses on the wider translocal consequences of NbS projects. The theoretical reflections are illustrated with case studies of NbS from various countries: the recognition of marginalised women in Vietnam in mangrove restoration projects, the challenges when introducing procedural justice in implementing NbS in Serbia, the legal injustices locals are faced in the Czech Republic when they want to implement NbS, the trade-off between public collective and individual economic interest when implementing a sand nourishment project in the Netherlands, and the development of a beneficiary-pays based upstream–downstream compensation scheme in Austria