A5004317310- Oceanographic and Atmospheric Processes
- Climate variability and models
- Meteorological Phenomena and Simulations
- Ocean Waves and Remote Sensing
- Tropical and Extratropical Cyclones Research
- Solar and Space Plasma Dynamics
- Marine and coastal ecosystems
- Methane Hydrates and Related Phenomena
- Advanced Thermodynamics and Statistical Mechanics
- Geophysics and Gravity Measurements
- Atmospheric and Environmental Gas Dynamics
- Fluid Dynamics and Turbulent Flows
- Geology and Paleoclimatology Research
- Global Energy and Sustainability Research
- Hydrocarbon exploration and reservoir analysis
- Arctic and Antarctic ice dynamics
- Spectroscopy and Quantum Chemical Studies
- Ocean Acidification Effects and Responses
- Spacecraft and Cryogenic Technologies
- Geological formations and processes
- Ionosphere and magnetosphere dynamics
- Statistical Mechanics and Entropy
- Geological and Geophysical Studies
- Phase Equilibria and Thermodynamics
- Atmospheric aerosols and clouds
University of Reading
2016-2025
National Institute of Meteorology
2021
Scripps Institution of Oceanography
2019
University of California, San Diego
2019
Laboratoire de Météorologie Dynamique
2001-2006
University of Cape Town
2004-2006
Sorbonne Université
2001-2006
Centre National de la Recherche Scientifique
2004
Institut Pierre-Simon Laplace
2004
Planetary Science Institute
2000-2001
Abstract An idealized case‐study has been designed to investigate the modelling of diurnal cycle deep precipitating convection over land. A simulation this case was performed by seven single‐column models (SCMs) and three cloud‐resolving (CRMs). Within framework, a quick onset convective rainfall is found in most SCMs, consistent with results from general‐circulation models. In contrast, CRMs do not predict before noon. joint analysis provided both types model indicates that occurs too early...
Abstract The North Atlantic eddy-driven jet exhibits latitudinal variability with evidence of three preferred locations: south, middle, and north. Here the authors examine drivers this associated storm track. investigate changes in storm-track characteristics for locations propose a mechanism by which enhanced activity, as measured upstream heat flux, is responsible cyclical downstream shifts jet. This based on nonlinear oscillator relationship between meridional temperature gradient (and...
Lorenz's theory of available potential energy (APE) remains the main framework for studying atmospheric and oceanic cycles. Because APE generation rate is volume integral a thermodynamic efficiency times local diabatic heating/cooling rate, often regarded as an extension heat engines. Available energetics in classical thermodynamics, however, usually relies on concept exergy measured relative to reference-state maximizing entropy at constant energy, whereas APE's reference state minimizes...
The static energy encodes all possible information about the thermodynamics and potential (and related forces) of stratified geophysical fluids. In this paper, we develop a systematic methodology, called asymptotics, that exploits property for constructing energetically thermodynamically consistent sound-proof approximations equations motion. By approximating to various orders accuracy, two main families are (re-)derived discussed: pseudo-incompressible (PI) approximation anelastic (AN)...
A key issue in stratified turbulence theory concerns the nature of link between D(APE), dissipation rate available potential energy APE, and W_{r,turbulent}, turbulent change background gravitational GPE_r, which are both controlled by molecular diffusion. For Boussinesq fluids with a linear equation state, this is simply W_{r,turbulent}=D(APE), widely interpreted as implying that GPE_r increases at expense contrast laminar case where internal (IE). This idea revisited here regarding IE sum...
Abstract This paper provides a comprehensive derivation of the total energy equations for atmospheric components Earth System Models (ESMs). The assumptions and approximations made in this are motivated discussed. In particular, it is emphasized that closing budget conceptually challenging hard to achieve practice without resorting ad hoc fixers. As concrete example, terms diagnosed realistic climate simulation using global atmosphere model. largest errors example spurious dynamical core...
Because it allows a rigorous separation between reversible and irreversible processes, the concept of available potential energy (APE) has become central to study turbulent stratified fluids. In ocean modelling, is fundamental parameterisation meso-scale eddies mixing heat salt. However, how apply APE theory consistently local or regional subdomains been longstanding source confusion due globally defined Lorenz reference state entering definition buoyancy forces being generally thought be...
Abstract In layered models of the ocean, assumption a deep resting layer is often made, motivated by surface intensification many phenomena. The propagation speed first-mode, baroclinic Rossby waves in such always faster than with all layers active. deep-resting not crucial for phase-speed enhancement since same result holds if bottom pressure fluctuations are uncorrelated from overlying wave dynamics. this paper authors explore relevance behavior to recent observational estimates “too-fast”...
The concept of density or isopycnal sufaces forms the backbone our understanding numerous aspects ocean circulation. It is central to study quasi-geostrophic motions, potential vorticity, lateral stirring, and Atlantic meridional overturning circulation, among others. well known, however, that identification such surfaces greatly complicated by thermobaric nonlinearity equation state. So far, prevailing paradigm has been should be empirically constructed as neutral material feasible. Because...
Atmosphere–ocean general circulation models (AOGCMs) predict a weakening of the Atlantic meridional overturning (AMOC) in response to anthropogenic forcing climate, but there is large model uncertainty magnitude predicted change. The AMOC generally understood be result increased buoyancy input north warmer leading reduced convection and deep water formation. Consistent with this idea, analyses have shown empirical relationships between density gradient, link not direct because large-scale...
Abstract Recent empirical and modelling studies suggest that mid‐tropospheric relative humidity ( RH ) is an important controlling factor of deep atmospheric convection, which appears to be underestimated in present cumulus parametrizations. This indicates the possible presence shortcomings way entrainment represented such matter was explored European Cloud Systems project (EUROCS) by means idealized experiment main parameter . In latter study, cloud‐resolving model (CRM) experiments...
Abstract. We compare the variability of Atlantic meridional overturning circulation (AMOC) as simulated by coupled climate models RAPID project, which cover a wide range resolution and complexity, observed RAPID/MOCHA array at about 26° N. analyse on timescales, from five-daily to interannual. In all resolutions there is substantial timescales few days; in most AOGCMs amplitude somewhat larger magnitude than that array, while time-mean within 10 % observational estimate. The annual cycle...
Abstract The study of the mechanical energy budget oceans using Lorenz available potential (APE) theory is based on knowledge adiabatically rearranged reference state minimum energy. compressible and nonlinear character equation for seawater has been thought to cause be ill defined, casting doubt usefulness APE investigating ocean energetics under realistic conditions. Using a method volume frequency distribution parcels as function temperature salinity in context Boussinesq approximation,...
Abstract In this paper, the concept of available potential energy (APE) density is extended to a multicomponent Boussinesq fluid with nonlinear equation state. As shown by previous studies, APE naturally interpreted as work against buoyancy forces that parcel needs perform move from notional reference position at which its vanishes actual position; because can be defined relative an arbitrary state, so density. The therefore best viewed defining class locally quantities, each tied different...
We extend the local theory of available potential energy (APE) to a general multicomponent compressible stratified fluid, accounting for effects diabatic sinks and sources. As simple fluids, total density fluid parcel is sum its elastic APE density. These respectively represent adiabatic compression/expansion work needed bring it from reference pressure actual against buoyancy forces required move state position position. Our expression new derived using only elementary manipulations...
Abstract The effect of a baroclinic mean flow on long oceanic Rossby waves is studied using combination analytical and numerical solutions the eigenvalue problem. summarized by value nondimensional numberwhen shear keeps constant sign throughout water column. Because previous studies have shown that no interaction occurs if has shape first unperturbed mode (the non–Doppler shift effect), an implicit assumption in application present work to real ocean relative projections second higher modes...
This letter argues that the current controversy about whether W buoyancy , power input due to surface fluxes, is large or small in oceans stems from two distinct and incompatible views on how relates volume‐integrated work of expansion/contraction B . The prevailing view should be identified with net value which theories estimate small. alternative view, defended here, only positive part i.e., one converting internal energy into mechanical energy, enter definition since negative associated...
Abstract A key idea in the study of Atlantic meridional overturning circulation (AMOC) is that its strength proportional to density gradient or, more precisely, pressure gradient. physical basis would indicate how estimate relevant locally from distribution numerical ocean models test such an has been lacking however. Recently, studies energetics have suggested AMOC driven by release available potential energy (APE) into kinetic (KE) and a conversion takes place primarily deep western...
A predator–prey relationship between storm track intensity and growth rate is revealed in reanalysis data of the North Atlantic Pacific, as well an idealized global circulation model with a zonally asymmetric heating dipole. Averaging phase space these two quantities reveals that both oscillate on approximately monthly time‐scales. These oscillations occur due to quasi‐periodic bursts activity reduce excess baroclinicity bring flow back towards state marginally stable those bursts. Many...