Preprints

Filtering by Subject: Oceanography and Atmospheric Sciences and Meteorology

High-resolution observations of the North Pacific transition layer from a Lagrangian float

Alexis Kaminski, Eric A. D'Asaro, Andrey Y. Shcherbina, Ramsey R. Harcourt

Published: 2021-02-11
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

A crucial region of the ocean surface boundary layer (OSBL) is the strongly-sheared and -stratified transition layer (TL) separating the mixed layer from the upper pycnocline, where a diverse range of waves and instabilities are possible. Previous work suggests that these different waves and instabilities will lead to different OSBL behaviours. Therefore, understanding which physical processes [...]

Reduced High-Latitude Land Seasonality in Climates with Very High Carbon Dioxide

Matthew Henry, Geoffrey K Vallis

Published: 2021-02-10
Subjects: Atmospheric Sciences, Climate, Oceanography and Atmospheric Sciences and Meteorology

Observations of warm past climates and projections of future climate change show that the Arctic warms more than the global mean, particularly during winter months. Past warm climates such as the early Eocene had above-freezing Arctic continental temperatures year-round. In this paper, we show that a reduced Arctic land seasonality with increased greenhouse gases is a robust consequence of the [...]

Dynamical attribution of North Atlantic interdecadal predictability to oceanic and atmospheric turbulence under realistic and optimal stochastic forcing

Dafydd Stephenson, Florian Sévellec

Published: 2021-02-01
Subjects: Climate, Environmental Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Unpredictable variations in the ocean originate from both external atmospheric forcing and chaotic processes internal to the ocean itself, and are a crucial sink of predictability on interdecadal timescales. In a global ocean model, we present i.) an optimisation framework to compute the most efficient noise patterns to generate uncertainty and ii.) a uniquely inexpensive, dynamical method for [...]

Observations of nonlinear momentum fluxes over the inner continental shelf

Thomas Pell Connolly, Steven J Lentz

Published: 2021-01-31
Subjects: Oceanography and Atmospheric Sciences and Meteorology

Nonlinear momentum fluxes over the inner continental shelf are examined using moored observations from multiple years at two different locations in the Middle Atlantic Bight. Inner shelf dynamics are often described in terms of a linear alongshore momentum balance, dominated by frictional stresses generated at the surface and bottom. In this study, observations over the North Carolina inner shelf [...]

The active and passive roles of the ocean in generating basin-scale heat content variability

Dafydd Stephenson, Florian Sévellec

Published: 2021-01-28
Subjects: Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

The role of ocean circulation in transforming surface forcing into interannual-to-multidecadal oceanic variability is an area of ongoing debate. Here, a novel method, establishing exact causal links, is used to quantitatively determine the role of ocean active and passive processes in transforming stochastic surface forcing into heat content variability. To this end, we use a global ocean model [...]

Vertical fluxes conditioned on vorticity and strain reveal submesoscale ventilation

Dhruv Balwada, Qiyu Xiao, Shafer Smith, Ryan Abernathey, Alison Gray

Published: 2021-01-24
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology

It has been hypothesized that submesoscale flows play an important role in the vertical transport of climatically important tracers, due to their strong associated vertical velocities. However, the multi-scale, non-linear and Lagrangian nature of transport makes it challenging to attribute proportions of the tracer fluxes to certain processes, scales, regions or flow features. Here we show that [...]

An idealized 1.5-layer isentropic model with convection and precipitation for satellite data assimilation research. Part II: model derivation

Onno Bokhove, Luca Cantarello, Steven Tobias

Published: 2021-01-22
Subjects: Applied Mathematics, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

In this part II paper we present the analytical derivation of the isentropic 1.5-layer shallow water model described and used in part I of this study. The mathematical derivation presented here is based on a combined asymptotic and slaved Hamiltonian analysis. The scaling assumptions throughout the paper are supported by real observations based on radiosonde data. Eventually, a fully consistent [...]

An idealized 1.5-layer isentropic model with convection and precipitationfor satellite data assimilation research. Part I: model dynamics

Luca Cantarello, Onno Bokhove, Steven Tobias

Published: 2021-01-22
Subjects: Applied Mathematics, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

An isentropic 1.5-layer model based on modified shallow water equations is presented, including terms mimicking convection and precipitation. This model is an updated version of the isopycnal single-layer modified shallow water model presented in Kent et al. (2017). The clearer link between fluid temperature and model variables together with a double-layer structure make this revised, isentropic [...]

Decrease in air-sea CO2 fluxes caused by persistent marine heatwaves

Alex Mignot, Karina Von Schuckmann, Florent Gasparin, Simon van Gennip, Peter Landschützer, Coralie Perruche, Julien Lamouroux, Tristan Amm

Published: 2021-01-21
Subjects: Oceanography and Atmospheric Sciences and Meteorology

Regional processes play a key role in the global carbon budget. Major ocean carbon uptake at mid-latitudes counteracts carbon release in the tropics, which is modulated by episodes of marine heatwaves (MHWs). Yet, we lack essential knowledge on persistent MHWs (PMHWs), and their effect on the carbon sensitive areas. Here, based on a 1985-2017 joint analysis of reconstructions, ocean reanalysis, [...]

Near-inertial dissipation due to stratified flow over abyssal topography

Varvara E Zemskova, Nicolas Grisouard

Published: 2021-01-12
Subjects: Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Linear theory for steady stratified flow over topography sets the range for topographic wavenumbers over which freely propagating internal waves are generated, and the radiation and breaking of these waves contribute to energy dissipation away from the ocean bottom. However, previous numerical work demonstrated that dissipation rates can be enhanced by flow over large scale topographies with [...]

Yield estimation of the 2020 Beirut explosion using open access waveform and remote sensing data

Christoph Pilger, Patrick Hupe, Peter Gaebler, Andre Kalia, Felix Schneider, Andreas Steinberg, Sudhaus Henriette, Lars Ceranna

Published: 2020-12-22
Subjects: Applied Statistics, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Physics, Statistics and Probability

We report on a multi-technique analysis using publicly available data for investigating the huge, accidental explosion that struck the city of Beirut, Lebanon, on August 4, 2020. Its devastating shock wave led to thousands of injured with more than two hundred fatalities and caused immense damage to buildings and infrastructure. Our combined analysis of seismological, hydroacoustic, infrasonic [...]

Idealized forecast-assimilation experiments for convective-scale Numerical Weather Prediction

Thomas Kent, Luca Cantarello, Gordon Inverarity, Steven Tobias, Onno Bokhove

Published: 2020-12-18
Subjects: Meteorology, Oceanography and Atmospheric Sciences and Meteorology

To aid understanding of and facilitate research into forecast-assimilation systems of Numerical Weather Prediction (NWP), idealized models that embody essential characteristics of these systems can be used. This article concerns the use of such an idealized fluid model of convective-scale NWP in inexpensive data assimilation (DA) experiments. The forecast model, introduced in Kent et al (2017), [...]

The influence of orbital parameters on the North American Monsoon system during the Last Interglacial Period

Nadja Insel, Max Berkelhammer

Published: 2020-12-17
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Environmental Sciences, Hydrology, Oceanography and Atmospheric Sciences and Meteorology

The response of summer precipitation in the western U.S. to climate variability remains a subject of uncertainty. For example, paleoclimate records indicate the North American monsoon (NAM) was stronger and spatially more extensive during the Holocene, whereas recent modeling suggests a weakened NAM response to increasing temperatures. These illustrate diverging pictures of the NAM response to [...]

Climate change research and action must look beyond 2100

Christopher Lyon, Erin E Saupe, Christopher J Smith, Daniel J Hill, Andrew P Beckerman, Lindsay C Stringer, Robert Marchant, James McKay, Ariane Burke, Paul O'Higgins, Alexander M Dunhill, Bethany J Allen, Julien Riel-Salvatore, Tracy Aze

Published: 2020-12-16
Subjects: Environmental Sciences, Environmental Studies, Geography, Human Geography, Nature and Society Relations, Oceanography and Atmospheric Sciences and Meteorology, Physical and Environmental Geography, Physical Sciences and Mathematics, Social and Behavioral Sciences

Anthropogenic activity is changing Earth’s climate and ecosystems in ways that are potentially dangerous and disruptive to humans. Greenhouse gas concentrations in the atmosphere continue to rise, ensuring these changes will be felt for centuries beyond 2100, the current benchmark for prediction. Estimating the effects of past, current, and potential future emissions to only 2100 is therefore [...]

Differences in carbon isotope discrimination between angiosperm and gymnosperm woody plants, and their relationship to atmospheric O2:CO2 ratio, physiology, and environment

Vincent John Hare, Aliénor Lavergne

Published: 2020-12-13
Subjects: Biogeochemistry, Climate, Geochemistry, Oceanography and Atmospheric Sciences and Meteorology, Paleobiology

For most of the Phanerozoic Eon, Earth’s woody vegetation has been dominated by C3 plants – predominantly gymnosperms - with angiosperms only emerging as the dominant plant group as CO2 declined during the Cenozoic (66 Ma onward). At present, differences in carbon isotope discrimination (Δ13C) between angiosperm and gymnosperm plants are relatively small (2–3 ‰), but an increasing body of [...]

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