Reduced viscosity steadily weakens oceanic currents

<p>Highland environments are rarely preserved in the geological record, particularly from as early as the Paleozoic Era. However, several stratigraphic locations are now known which definitely or potentially preserve such environments near the paleoequator during the Late Carboniferous and Early Permian Periods, during which the Earth was in the depths of an icehouse climate like that of the Pliocene and Pleistocene Epochs, the Late Paleozoic Ice Age (LPIA). Several of these locations contain evidence of mountain glaciation at altitudes below 2000 m, leading to questions about the significance of tropical mountain glaciation for global climate during this interval of geologic time. However, climate model simulations for the LPIA have not been able to simulate mountain glaciation like that inferred from the geological record, possibly because of low resolution, incorrect boundary conditions, or climate model bias resulting from incomplete representation of moist convective processes impacting tropical lapse rates. </p><p>The overarching purpose of this study is to develop a climate modeling framework that enables the significance of mountain glaciation for global paleoclimate to be evaluated. Ideally, such a framework would allow low-resolution global model output to be downscaled to the scale of a mountain range to calculate the equilibrium line altitude and similar parameters, enabling evidence of mountain glaciation in the deep past to be used to constrain/tune the low-resolution global models. While this study was designed to inform a specific problem in deep time paleoclimate, its results are likely broadly applicable to assessing how well mountain glaciation is captured by global climate modeling of the past, present, and future.   </p><p>Here, I present a framework in which the CMIP6 pre-industrial control simulation for the Community Earth System Model version 2 (CESM2) at 0.9°x1.25° resolution is used to generate a data atmosphere for the Community Land Model version 5 (CLM5) run at 0.01° resolution in 10 tropical and 1 mid-latitude domain to study the surface mass balance over the domain. For computational reasons, glaciation is assumed to cover a small portion of each grid cell, but surface mass balance still can be evaluated. Topographic boundary conditions come from GMTED2010, but most other information is directly interpolated from the CESM2 simulation. CLM5 simulations require a fixed lapse rate to be assumed, which is varied in each CLM5 simulation across six different values. The CLM5 simulation output along with the mean tropical lapse rate in the CESM2 simulation is then used to evaluate the various biases of this framework in comparison with estimated pre-industrial equilibrium line altitudes for the studied domains.</p><p>This work is supported by the National Science Foundation (USA) under grant EAR-1849754. </p>

In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth-analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like modern Earth), and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3 times the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The temperate obliquity seasons are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal lightcurves as they would appear to a high-contrast imaging mission (TPF-I/Darwin) and consider the inverse problem of estimating thermal inertia based solely on time-resolved photometry. [Abridged]

The degree to which total meridional heat transport is sensitive to the details of its atmospheric and oceanic components is explored. A coupled atmosphere, ocean, and sea ice model of an aquaplanet is employed to simulate very different climates—some with polar ice caps, some without—even though they are driven by the same incoming solar flux. Differences arise due to varying geometrical constraints on ocean circulation influencing its ability to transport heat meridionally. Without complex land configurations, the results prove easier to diagnose and compare to theory and simple models and, hence, provide a useful test bed for ideas about heat transport and its partition within the climate system. In particular, the results are discussed in the context of a 1978 study by Stone, who argued that for a planet with Earth’s astronomical parameters and rotation rate, the total meridional heat transport would be independent of the detailed dynamical processes responsible for that transport and depend primarily on the distribution of incoming solar radiation and the mean planetary albedo. The authors find that in warm climates in which there is no ice, Stone’s result is a useful guide. In cold climates with significant polar ice caps, however, meridional gradients in albedo significantly affect the absorption of solar radiation and need to be included in any detailed calculation or discussion of total heat transport. Since the meridional extent of polar ice caps is sensitive to details of atmospheric and oceanic circulation, these cannot be ignored. Finally, what has been learned is applied to a study of the total heat transport estimated from the Earth Radiation Budget Experiment (ERBE) data.

Inclined turbulent thermal convection in liquid sodium is studied at large Rayleigh numbers based on the results of both experimental measurements and high-resolution numerical simulations. For a direct comparison, the considered system parameters are set to be similar: in the direct numerical simulations (DNS), in the large-eddy simulations and in the experiments, while the Prandtl number of liquid sodium is very small ( ). The cylindrical convection cell has an aspect ratio of one; one circular surface is heated, while the other one is cooled. Additionally, the cylinder is inclined with respect to gravity and the inclination angle varies from , which corresponds to Rayleigh–Benard convection (RBC), to , as in a vertical convection (VC) set-up. Our study demonstrates quantitative agreement of the experimental and numerical results, in particular with respect to the global heat and momentum transport, temperature and velocity profiles, as well as the dynamics of the large-scale circulation (LSC). The DNS reveal that the twisting and sloshing of the LSC at small inclination angles periodically affects the instantaneous heat transport (up to of the mean heat transport). The twisted LSC is associated with a weak heat transport, while the sloshing mode that brings together the hot and cold streams of the LSC is associated with a strong heat transport. The experiments show that the heat transport scales as in both limiting cases (RBC and VC) for Rayleigh numbers around , while any inclination of the cell, , leads to an increase of .

Twentieth century sea-level rise inferred from tide gauge, geologically derived and thermosteric sea-level changes

A crucial branch of science called climate modeling uses mathematical equations and computer simulations to study and forecast the Earth's climate sys- tem. The main elements of climate modeling, such as general circulation models (GCMs), data assimilation methods, and numerical formulations, are outlined in this paper. GCMs, which include grid point and spectral models, are effective instruments for examining the behavior of the climate. Four-Dimensional Data Assimilation (4D-Var) is one example of a data assimilation technique that in- corporates observational data into models to improve their correctness. Numeri cal methods, ocean dynamics, heat transport, radiative transfer, and atmospheric dynamics are all included in numerical formulations. The simulation of different climate processes is possible because to these mathematical representations. Fur thermore, the detection of precipitation patterns within climate modeling is using machine learning techniques like Random Forest more frequently. This paper highlights the importance of high-performance computing (HPC) in climate modeling, boosting efficiency and simulations, in the context of research technique. Advanced data assimilation and validation techniques are also examined, as well as the influence of high-resolution modeling on small-scale climatic processes. On HPC platforms, accessibility to climate modeling is addressed. It is shown how climate modeling crosses physics, mathematics, computer science, and engineering to be interdisciplinary. A comprehensive understanding of the Earth's intricate climate system gains from the integration of all its parts, from atmospheric dynamics to data assimilation. We explore the consequences of these research approaches, their contribution to enhancing climate prediction models, and the influence of various factors on climatic variables in the debate. Climate modeling becomes an essential tool for studying precipitation patterns and climate change, ultimately improving our comprehension of the complex cli- mate system on Earth.

The chemistry and transport phenomena of chemical vapor deposition of silicon from SiCl 4

Role of hybrid nano-structures and dust particles on transportation of heat energy in fluid with memory effects

Future sea-level rise and its early detection by satellite remote sensing

Water vapour plays a key role in the Earth's energy balance. Almost 50% of the absorbed solar radiation at the surface is used to cool the surface, through evaporation, and warm the atmosphere, through release of latent heat. Latent heat is the single largest factor in warming the atmosphere and in transporting heat from low to high latitudes. Water vapour is also the dominant greenhouse gas and contributes to a warming of the climate system by some 24°C (Kondratev 1972). However, water vapour is a passive component in the troposphere as it is uniquely determined by temperature and should therefore be seen as a part of the climate feedback system. In this short overview, we will first describe the water on planet Earth and the role of the hydrological cycle: the way water vapour is transported between oceans and continents and the return of water via rivers to the oceans. Generally water vapour is well observed and analysed; however, there are considerable obstacles to observing precipitation, in particular over the oceans. The response of the hydrological cycle to global warming is far reaching. Because different physical processes control the change in water vapour and evaporation/precipitation, this leads to a more extreme distribution of precipitation making, in general, wet areas wetter and dry areas dryer. Another consequence is a transition towards more intense precipitation. It is to be expected that the changes in the hydrological cycle as a consequence of climate warming may be more severe that the temperature changes.

Hemispheric difference in the momentum transport by atmospheric waves in the Martian summer polar region was investigated by using the atmospheric temperature profiles taken by MGS TES. In the southern polar region, isolated zonal wave number‐1 temperature disturbances were prominent and upward EP (Eliassen‐Palm) fluxes were found indicating the existence of planetary waves, while they were obscure in the northern polar region. This north‐south difference is attributed to the difference in CO2 polar cap retreat: the asymmetric retreat of the southern polar cap which remains throughout the summer creates near‐surface temperature anomalies with the zonal wave number of unity and resultant planetary waves, while the nearly symmetric retreat of the northern polar cap do not create such disturbances. The momentum transport in the southern polar region will drive a localized meridional circulation with ascent at 70°S–80°S and descent over the pole. This meridional circulation would increase the atmospheric temperature by ∼10 K near the pole and transport dust that is lifted up by local dust storms.

The rate of ocean heat uptake depends on the mechanisms that transport heat between the surface and the ocean interior. A recent study found that the vertical heat transport driven by motions with scales smaller than 0.5° (submesoscales) and frequencies smaller than 1 day−1 is upward. This transport competes with the other major components of the global heat transport, namely, the downward heat transport explained by the large‐scale wind‐driven vertical circulation and vertical diffusion at small scales and the upward heat transport associated with mesoscale eddies (50‐ to 300‐km size). The contribution from motions with small spatial scales (<0.5°) and frequencies larger than 1 day−1, including internal gravity waves, has never been explicitly estimated. This study investigates this high‐frequency (subdaily) submesoscale contribution to the global heat transport. The major result of this study, based on the analysis of a high‐resolution ocean model, is that including this high‐frequency contribution surprisingly doubles the upward heat transport due to submesoscales in winter in the global ocean. This contribution typically concerns depths down to 200–500 m and can have a magnitude of up to 500 W m−2 in terms of wintertime heat fluxes at 40‐m depth, which causes a significant upward heat transport of ~7 PW when integrated over the global ocean. Thus, such submesoscale heat transport, which is not resolved by climate models, impacts the heat uptake in the global ocean. The mechanisms involved in these results still need to be understood, which should be the scope of future work.

Any tilt of a Rayleigh–Bénard convection cell against gravity changes the global flow structure inside the cell, which leads to a change of the heat and momentum transport. Especially sensitive to the inclination angle is the heat transport in low-Prandtl-number fluids and confined geometries. The purpose of the present work is to investigate the global flow structure and its influence on the global heat transport in inclined convection in a cylindrical container of diameter-to-height aspect ratio $\unicode[STIX]{x1D6E4}=1/5$. The study is based on direct numerical simulations where two different Prandtl numbers $Pr=0.1$ and 1.0 are considered, while the Rayleigh number, $Ra$, ranges from $10^{6}$ to $10^{9}$. For each combination of $Ra$ and $Pr$, the inclination angle is varied between 0 and $\unicode[STIX]{x03C0}/2$. An optimal inclination angle of the convection cell, which provides the maximal global heat transport, is determined. For inclined convection we observe the formation of two system-sized plume columns, a hot and a cold one, that impinge on the opposite boundary layers. These are related to a strong increase in the heat transport.

Marine Energy is not necessarily same as Ocean Power. Marine energy can be created in the ocean as also in rivers, lakes, streams, estuaries, and more. The difference between ocean energy and tidal energy is that tidal energy uses gravitational pull of earth, moon and sun to produce energy whereas wave energy uses kinetic forces of waves to generate electricity. The tides at shorelines of oceans will rise and fall twice a day. Marine energy or marine power is also referred to as ocean energy, ocean power, or marine and hydrokinetic energy. energy refer to the energy carried by ocean waves, tides salinity, and ocean temperature differences. The movement of water in the world’s oceans creates a vast store of kinetic energy, or energy in motion. Some of this energy can be harnessed to generate electricity to power homes, transport and industries. The term marine energy encompasses both wave power i.e., power from surface waves, and tidal power obtained from the kinetic energy of large bodies of moving water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world. substantial amount of renewable energy around the world.

Ocean heat transport in the South Atlantic of a coupled climate model has been diagnosed and compared with observational estimates. The coupled model overestimates the northward heat transport in the South Atlantic. This corresponds to an underestimate of the northward flux of bottom water across World Ocean Circulation Experiment (WOCE) section A11 (the model transports less than 1 Sv compared with climatological estimates of 6 Sv). The magnitude of the southward outflow of North Atlantic deep water agrees well with observational estimates while the northward flux of surface and intermediate waters is larger than observational estimates. We show that with the correct water mass properties a realistic northward flux of bottom water across 30°S is only possible, in the climate model, if the depths of the channels linking the Argentine and Brazil basins are properly represented. We find that an increase in the northward flow of bottom water corresponds to an increase in the southward flow of deep water, rather than a reduction in the northward flux of surface and intermediate waters. This indicates that the upper and lower limb of the overturning are decoupled in the model. As a consequence, increasing the northward transport of bottom water leads to a small reduction of the northward heat transport across 30°S. The magnitude of the heat transport from the Indian to the Atlantic ocean in the model (the warm water path) is surprisingly large for a noneddy resolving model. We find that the magnitude of the Indonesian Throughflow is important in climate resolution models for determining the strength of the warm water path. However, the relative strengths of the warm and cold water paths do not significantly change the heat transported across 30°S.