An AUV-Based Investigation of the Role of Nutrient Variability in the Predictive Modeling of Physical Processes in the Littoral Ocean

2003 ◽  
Author(s):  
Kent A. Fanning ◽  
John Walsh
Keyword(s):  
Predictive Modeling ◽  
Physical Processes ◽  
Nutrient Variability

scholarly journals Recent Decadal Changes in Heat Waves over China: Drivers and Mechanisms

2019 ◽  
Vol 32 (14) ◽  
pp. 4215-4234 ◽  
Author(s):  
Qin Su ◽  
Buwen Dong
Keyword(s):  
Heat Waves ◽  
Asian Summer Monsoon ◽  
Early Period ◽  
Spatial Extent ◽  
Physical Processes ◽  
Southeastern China ◽  
Anthropogenic Aerosol ◽  
Asian Summer ◽  
Frequency Intensity

Abstract Observational analysis indicates significant decadal changes in daytime, nighttime, and compound (both daytime and nighttime) heat waves (HWs) over China across the mid-1990s, featuring a rapid increase in frequency, intensity, and spatial extent. The variations of these observed decadal changes are assessed by the comparison between the present day (PD) of 1994–2011 and the early period (EP) of 1964–81. The compound HWs change most remarkably in all three aspects, with frequency averaged over China in the PD tripling that in the EP and intensity and spatial extent nearly doubling. The daytime and nighttime HWs also change significantly in all three aspects. A set of numerical experiments is used to investigate the drivers and physical processes responsible for the decadal changes of the HWs. Results indicate the predominant role of the anthropogenic forcing, including changes in greenhouse gas (GHG) concentrations and anthropogenic aerosol (AA) emissions in the HW decadal changes. The GHG changes have dominant impacts on the three types of HWs, while the AA changes make significant influences on daytime HWs. The GHG changes increase the frequency, intensity, and spatial extent of the three types of HWs over China both directly via the strengthened greenhouse effect and indirectly via land–atmosphere and circulation feedbacks in which GHG-change-induced warming in sea surface temperature plays an important role. The AA changes decrease the frequency and intensity of daytime HWs over Southeastern China through mainly aerosol–radiation interaction, but increase the frequency and intensity of daytime HWs over Northeastern China through AA-change-induced surface–atmosphere feedbacks and dynamical changes related to weakened East Asian summer monsoon.

scholarly journals Atlantic Hurricanes and Climate Change. Part II: Role of Thermodynamic Changes in Decreased Hurricane Frequency

2013 ◽  
Vol 26 (21) ◽  
pp. 8513-8528 ◽  
Author(s):  
Megan S. Mallard ◽  
Gary M. Lackmann ◽  
Anantha Aiyyer
Keyword(s):  
Case Studies ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Effect Of Temperature ◽  
Physical Processes ◽  
Thermodynamic Conditions ◽  
Atlantic Hurricanes ◽  
Reduced Activity

Abstract A method of downscaling that isolates the effect of temperature and moisture changes on tropical cyclone (TC) activity was presented in Part I of this study. By applying thermodynamic modifications to analyzed initial and boundary conditions from past TC seasons, initial disturbances and the strength of synoptic-scale vertical wind shear are preserved in future simulations. This experimental design allows comparison of TC genesis events in the same synoptic setting, but in current and future thermodynamic environments. Simulations of both an active (September 2005) and inactive (September 2009) portion of past hurricane seasons are presented. An ensemble of high-resolution simulations projects reductions in ensemble-average TC counts between 18% and 24%, consistent with previous studies. Robust decreases in TC and hurricane counts are simulated with 18- and 6-km grid lengths, for both active and inactive periods. Physical processes responsible for reduced activity are examined through comparison of monthly and spatially averaged genesis-relevant parameters, as well as case studies of development of corresponding initial disturbances in current and future thermodynamic conditions. These case studies show that reductions in TC counts are due to the presence of incipient disturbances in marginal moisture environments, where increases in the moist entropy saturation deficits in future conditions preclude genesis for some disturbances. Increased convective inhibition and reduced vertical velocity are also found in the future environment. It is concluded that a robust decrease in TC frequency can result from thermodynamic changes alone, without modification of vertical wind shear or the number of incipient disturbances.

scholarly journals Greedy measurement selection for state estimation

2018 ◽  
Author(s):  
J. Nichols ◽  
Albert Cohen ◽  
Peter Binev ◽  
Olga Mula
Keyword(s):  
Hilbert Space ◽  
Differential Operator ◽  
High Dimensional ◽  
Dimensional Vector ◽  
Physical Processes ◽  
Linear Measurements ◽  
Measurement Selection ◽  
Selection For ◽  
Unknown Solution

Parametric PDEs of the general form $$ \mathcal{P}(u,a)=0 $$ are commonly used to describe many physical processes, where $\mathcal{P}$ is a differential operator, a is a high-dimensional vector of parameters and u is the unknown solution belonging to some Hilbert space V. Typically one observes m linear measurements of u(a) of the form $\ell_i(u)=\langle w_i,u \rangle$, $i=1,\dots,m$, where $\ell_i\in V'$ and $w_i$ are the Riesz representers, and we write $W_m = \text{span}\{w_1,\ldots,w_m\}$. The goal is to recover an approximation $u^*$ of u from the measurements. The solutions u(a) lie in a manifold within V which we can approximate by a linear space $V_n$, where n is of moderate dimension. The structure of the PDE ensure that for any a the solution is never too far away from $V_n$, that is, $\text{dist}(u(a),V_n)\le \varepsilon$. In this setting, the observed measurements and $V_n$ can be combined to produce an approximation $u^*$ of u up to accuracy $$ \Vert u -u^*\Vert \leq \beta^{-1}(V_n,W_m) \, \varepsilon $$ where $$ \beta(V_n,W_m) := \inf_{v\in V_n} \frac{\Vert P_{W_m}v\Vert}{\Vert v \Vert} $$ plays the role of a stability constant. For a given $V_n$, one relevant objective is to guarantee that $\beta(V_n,W_m)\geq \gamma >0$ with a number of measurements $m\geq n$ as small as possible. We present results in this direction when the measurement functionals $\ell_i$ belong to a complete dictionary.

Becoming Gypsy: Tell Me What the Body Knows in Flamenco Dance

2015 ◽  
Vol 6 (1) ◽  
pp. 22-35
Author(s):  
Diane Oatley
Keyword(s):  
Knowledge Acquisition ◽  
The Body ◽  
Physical Interaction ◽  
Embodied Knowledge ◽  
Physical Processes ◽  
The Unconscious ◽  
The World ◽  
Language And Cognition ◽  
Experiences Of Women

Abstract In The Meaning of the Body, philosopher Mark Johnson makes a case for the significance of movement in terms of the body processes he holds as essential to the generation of meaning and knowledge acquisition in physical interaction with the world–equally essential as language and cognition. The article employs this theory in interpreting the experiences of women learning flamenco dance in Spain. The investigation of the perceptions of women studying flamenco dance, a dance tradition often defined as “gypsy,” indicates that exposure to flamenco dance and culture leads to revision of stereotypes regarding embodiment and difference, but respondents did not relate this revision to bodily engagement, or physical processes particular to dancing flamenco. Although Johnson’s failure to properly account for the role of the unconscious proved to be a serious shortcoming in the theory, and one which had implications for the findings, application of the theory disclosed the parameters of a discourse on the body in flamenco. The theory thus represents a radical gesture in redefining embodiment in its own right in a manner that precludes dualism with the consequent opening of a range of alternative perspectives on the articulation of embodied knowledge.

scholarly journals Notes on the behaviour of trajectories of polynomial dynamic systems

2020 ◽  
Vol 313 ◽  
pp. 00014
Author(s):  
Irina Andreeva
Keyword(s):  
Dynamic Systems ◽  
Wide Spectrum ◽  
Modern Science ◽  
Seismic Stability ◽  
Phase Portraits ◽  
Main Task ◽  
Physical Processes ◽  
Science And Engineering ◽  
Research Stage

Dynamic systems play a key role in various directions of modern science and engineering, such as the mathematical modeling of physical processes, the broad spectrum of complicated and pressing problems of civil engineering, for example, in the analysis of seismic stability of constructions and buildings, in the fundamental studies of computing and producing systems, of biological and sociological events. A researcher uses a dynamic system as a mathematical apparatus to study some phenomena and conditions, under which any statistical events are not important and may be disregarded. The main task of the theory of dynamic systems is to study curves, which differential equations of this system define. During such a research, firstly we need to split a dynamic system’s phase space into trajectories. Secondly, we investigate a limit behavior of trajectories. This research stage is to reveal equilibrium positions and make their classification. Also, here we find and investigate sinks and sources of the system’s phase flow. As a result, we obtain a full set of phase portraits, possible for a taken family of differential dynamic systems, which describe a behavior of some process. Namely polynomial dynamic systems often play a role of practical mathematical models hence their investigation has significant interest. This paper represents the original study of a broad family of differential dynamic systems having reciprocal polynomial right parts, and describes especially developed research methods, useful for a wide spectrum of applications.

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