Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors

AbstractNon-radiatively heated outer atmospheres are common among stars on the cool side of the HR diagram. These atmospheres resemble that of the Sun in which the bulk of the heating is associated with magnetic fields. Consequently it is assumed that other cool stars also generate and maintain an internal magnetic field through a dynamo action. This field gives rise to a wide spectrum of phenomena in the stellar atmosphere. The dynamo process that sustains the field thrives on the interaction of rotation and turbulent convection. In this review I formulate a set of propositions outlining our present knowledge of this interaction as distilled from stellar observations. In doing so, I outline the effects of stellar evolution on rotation rate, discuss some of the proposed “dividing lines” in the HR-diagram, and comment on the possible role of the convective turnover time in dynamo efficiency and on dynamo activity for extremely slowly and rapidly rotating stars.

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Radiative-Convective Equilibrium Model Intercomparison Project

10.5194/gmd-2017-213 ◽

2017 ◽

Cited By ~ 2

Author(s):

Allison A. Wing ◽

Kevin A. Reed ◽

Masaki Satoh ◽

Bjorn Stevens ◽

Sandrine Bony ◽

...

Keyword(s):

General Circulation ◽

General Circulation Models ◽

Cloud Fraction ◽

Model Intercomparison ◽

Tropical Circulation ◽

Cloud Feedbacks ◽

Single Column ◽

Intercomparison Project ◽

Self Aggregation

Abstract. RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state, cloud feedbacks, and convective aggregation across the spectrum of models to be assessed. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, and single column models.

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Role of Satellite Sensors in Groundwater Exploration

Sensors ◽

10.3390/s8032006 ◽

2008 ◽

Vol 8 (3) ◽

pp. 2006-2016 ◽

Cited By ~ 13

Author(s):

Saumitra Mukherjee

Keyword(s):

Groundwater Exploration ◽

Satellite Sensors

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Bayesian deconstruction of climate sensitivity estimates using simple models: implicit priors, and the confusion of the inverse

10.5194/esd-2019-33 ◽

2019 ◽

Author(s):

James Annan ◽

Julia Hargreaves

Keyword(s):

Climate Sensitivity ◽

Bayesian Approach ◽

Bayesian Framework ◽

Observational Evidence ◽

Observational Constraints ◽

Heuristic Methods ◽

Uncertain Parameters ◽

Equilibrium Climate Sensitivity ◽

The Status

Abstract. Observational constraints on the equilibrium climate sensitivity have been generated in a variety of ways, but the epistemic basis of these calculations have not always been clearly presented and a number of results have been calculated which appear to be based on somewhat informal heuristics. This causes a lack of clarity about the status of such results and how they compare to other analyses, in particular whether the differences between them may be due to differences in unstated assumptions rather than observational evidence. In this paper, we show how these problems can be resolved. We demonstrate that many of these estimates can be reinterpreted within the standard subjective Bayesian framework in which a prior over the uncertain parameters is updated through a likelihood arising from observational evidence. In many of these cases, the prior which was (under this interpretation) implicitly used exhibits some unconventional and possibly undesirable properties. We present alternative calculations which use the same observational information to update a range of explicitly presented priors. Our calculations suggest that the heuristic methods do often generate reasonable results, in that they agree fairly well with the explicitly Bayesian approach using a reasonable prior. However, we also find some significant differences and argue that the explicitly Bayesian approach is preferred, as it both clarifies the role of the prior, and allows researchers to transparently test the sensitivity of their results to it.

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Modified Chaplygin Gas Cosmology

Advances in High Energy Physics ◽

10.1155/2012/357802 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 36

Author(s):

H. B. Benaoum

Keyword(s):

Scalar Field ◽

Cosmological Model ◽

Chaplygin Gas ◽

Observational Constraints ◽

Modified Chaplygin Gas ◽

Tachyonic Field ◽

The Relationship

Modified Chaplygin gas as an exotic fluid has been introduced by H. B. Benaoum (2002). Essential features of the modified Chaplygin gas as a cosmological model are discussed. Observational constraints on the parameters of the model have been included. The relationship between the modified Chaplygin gas and a homogeneous minimally coupled scalar field is reevaluated by constructing its self-interacting potential. In addition, we study the role of the tachyonic field in the modified Chaplygin gas cosmological model and the mapping between scalar field and tachyonic field is also considered.

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Building mountains

Gravitational-Wave Astronomy ◽

10.1093/oso/9780198568032.003.0014 ◽

2019 ◽

pp. 312-360

Author(s):

Nils Andersson

Keyword(s):

Magnetic Field ◽

Neutron Star ◽

Gravitational Waves ◽

Observational Constraints ◽

Neutron Star Crust

Different ways of generating continuous gravitational waves from a deformed rotating neutron star are discussed, starting with the physics of the neutron star crust and the modelling of elasticity and strain. A summary of observational constraints is provided. The role of the star’s interior magnetic field is considered. Accreting systems are explored and notion of precessing stars is discussed.

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