Atmospheric convection as an unstable predator-prey process with memory

2021 ◽  
Author(s):  
Maxime Colin ◽  
Steven C. Sherwood
Keyword(s):  
Large Scale ◽  
Rain Rate ◽  
Static Stability ◽  
Convective Precipitation ◽  
Small Scale ◽  
Quasi Equilibrium ◽  
Convective Activity ◽  
Atmospheric Convection ◽  
Predator Prey ◽  
Predator Prey Model

AbstractHeuristic models and observational analyses of atmospheric convection often assume that convective activity, for example rain rate, approaches some given value for any given large-scale (“macrostate”) environmental conditions such as static stability and humidity. We present novel convection-resolving simulations in which the convective activity evolves in a fixed equilibrium mean state (“macrostate”). In this case convective activity is unstable, diverging quasi-exponentially away from equilibrium either to extreme or zero rain rate. Thus almost any rain rate can coexist with an equilibrium profile: the model rain rate also depends on convective history. We then present a two-variable, predator-prey model motivated by this behavior, wherein small-scale (“microstate”) variability is produced by, but also promotes convective precipitation, while macrostate properties such as CAPE promote, but are consumed by convective precipitation. In this model, convection is influenced as much by its own history (via persistent microstate variability) as by its current environment. This model reproduces the simulated instability found above and could account for several lag relationships in simulated and observed convection, including its afternoon maximum over land and the well-known “quasi-equilibrium” balance at synoptic time scales between the forcing and response of key variables. These results point to a strong role for convective memory and suggests that basic strategies for observing, modeling and parameterizing convective processes should pay closer attention to persistent variability on scales smaller than that of the grid box.

The effects of obstacle size on periodic travelling waves in oscillatory reaction–diffusion equations

2007 ◽  
Vol 464 (2090) ◽  
pp. 365-390 ◽  
Author(s):  
Matthew J Smith ◽  
Jonathan A Sherratt ◽  
Nicola J Armstrong
Keyword(s):  
Large Scale ◽  
Order Approximation ◽  
Travelling Waves ◽  
Natural Populations ◽  
Reaction Diffusion ◽  
Field Studies ◽  
Reaction Diffusion Equations ◽  
Infinite Domain ◽  
Predator Prey ◽  
Predator Prey Model

Many natural populations undergo multi-year cycles, and field studies have shown that these can be organized into periodic travelling waves (PTWs). Mathematical studies have shown that large-scale landscape obstacles represent a natural mechanism for wave generation. Here, we investigate how the amplitude and wavelength of the selected waves depend on the obstacle size. We firstly consider a large circular obstacle in an infinite domain for a reaction–diffusion system of ‘ λ – ω ’ type. We use perturbation theory to derive a leading order approximation to the wave generated by the obstacle. This shows the dependence of the wave properties on both parameter values and obstacle size. We find that the limiting values of the amplitude and wavelength are approached algebraically with distance from the obstacle edge, rather than exponentially in the case of a flat boundary. We use our results to predict the properties of waves generated by a large circular obstacle for an oscillatory predator–prey system, via a reduction of the predator–prey model to normal form close to Hopf bifurcation. Our predictions compare well with numerical simulations. We also discuss the implications of these results for wave stability and briefly investigate the effects of obstacles with elliptical geometries.

scholarly journals Examination of a Stochastic and Deterministic Convection Parameterization in the COSMO Model

2015 ◽  
Vol 143 (10) ◽  
pp. 4088-4103 ◽  
Author(s):  
Kirstin Kober ◽  
Annette M. Foerster ◽  
George C. Craig
Keyword(s):  
Large Scale ◽  
Convective Precipitation ◽  
Small Scale ◽  
Synoptic Situation ◽  
Dependent Manner ◽  
Physical Processes ◽  
Verification Methods ◽  
Synoptic Forcing ◽  
Convection Parameterization

Abstract Stochastic parameterizations allow the representation of the small-scale variability of parameterized physical processes. This study investigates whether additional variability introduced by a stochastic convection parameterization leads to improvements in the precipitation forecasts. Forecasts are calculated with two different ensembles: one considering large-scale and convective variability with the stochastic Plant–Craig convection parameterization and one considering only large-scale variability with the standard Tiedtke convection parameterization. The forecast quality of both ensembles is evaluated in comparison with radar observations for two case studies with weak and strong synoptic forcing of convection and measured with neighborhood and probabilistic verification methods. The skill of the ensemble based on the Plant–Craig convection parameterization relative to the ensemble with the Tiedtke parameterization strongly depends on the synoptic situation in which convection occurs. In the weak forcing case, where the convective precipitation is highly intermittent, the ensemble based on the stochastic parameterization is superior, but the scheme produces too much small-scale variability in the strong forcing case. In the future, the degree of stochastic variability could be tuned, and these results show that parameters should be chosen in a regime-dependent manner.

scholarly journals Effective Diffusivity in Baroclinic Flow

2014 ◽  
Vol 71 (3) ◽  
pp. 972-984 ◽  
Author(s):  
Eric M. Leibensperger ◽  
R. Alan Plumb
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Effective Diffusivity ◽  
Static Stability ◽  
Small Scale ◽  
Tracer Transport ◽  
Theoretical Predictions ◽  
Diffusive Processes ◽  
Theoretical Developments

Abstract Large-scale chaotic stirring stretches tracer contours into filaments containing fine spatial scales until small-scale diffusive processes dissipate tracer variance. Quantification of tracer transport in such circumstances is possible through the use of Nakamura’s “effective diffusivity” diagnostics, which make clear the controlling role of stirring, rather than small-scale dissipation, in large-scale transport. Existing theory of effective diffusivity is based on a layerwise approach, in which tracer variance is presumed to cascade via horizontal (or isentropic) stirring to small-scale horizontal (or isentropic) diffusion. In most geophysical flows of interest, however, baroclinic shear will tilt stirred filamentary structures into almost-horizontal sheets, in which case the thinnest dimension is vertical; accordingly, it will be vertical (or diabatic) diffusion that provides the ultimate dissipation of variance. Here new theoretical developments define effective diffusivity in such flows. In the frequently relevant case of isentropic stirring, it is shown that the theory is, in most respects, unchanged from the case of isentropic diffusion: effective isentropic diffusivity is controlled by the isentropic stirring and, it is argued, largely independent of the nature of the ultimate dissipation. Diabatic diffusion is not amplified by the stirring, although it can be modestly enhanced through eddy modulation of static stability. These characteristics are illustrated in numerical simulations of a stratospheric flow; in regions of strong stirring, the theoretical predictions are well supported, but agreement is less good where stirring is weaker.

Use of High-Resolution DIDSON Sonar to Quantify Attributes of Predation at Ecologically Relevant Space and Time Scales

2013 ◽  
Vol 47 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Victoria E. Price ◽  
Peter J. Auster ◽  
Laura Kracker
Keyword(s):  
High Resolution ◽  
Time Scales ◽  
Large Scale ◽  
Multiple Scales ◽  
Predation Rate ◽  
Visual Observation ◽  
Small Scale ◽  
Dual Frequency ◽  
Predator Prey ◽  
Space And Time

AbstractPredator-prey interactions of large vagile fishes are difficult to study in the ocean due to limitations in the space and time requirements for observations. Small-scale direct underwater observations by divers (ca. <10 m radius) and large-scale hydroacoustic surveys (10 s m2 to 100 s km2) are traditional approaches for surveying fish. However, large piscivorous predators identify and attack prey at the scale of meters to tens of meters. Dual-Frequency Identification Sonar (or DIDSON) is a high-resolution acoustic camera operating in the MHz range that provides detailed continuous video-like imaging of objects up to a range of 30 m. This technology can be used to observe predator-prey interactions at ecologically relevant space and time scales often missed by traditional methods. Here we establish an approach for quantifying predation-related behaviors from DIDSON records. Metrics related to predator and prey group size, prey responses to predation, predation rate, predator strategies, and the nonrandom use of landscape features by both predator and prey are described. In addition, relationships between patterns in these attributes are tested and issues regarding sampling strategies for future studies are discussed. We suggest that approaches combining direct visual observation and acoustic sampling at multiple scales are required to quantify variation in these relationships across underwater landscapes.

scholarly journals Large Scale Experimental Study of the Scour Protection Damage Around a Monopile Foundation Under Combined Wave and Current Conditions

2020 ◽  
Vol 8 (6) ◽  
pp. 417 ◽  
Author(s):  
Minghao Wu ◽  
Leen De Vos ◽  
Carlos Emilio Arboleda Chavez ◽  
Vasiliki Stratigaki ◽  
Tiago Fazeres-Ferradosa ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Static Stability ◽  
Future Research ◽  
Small Scale ◽  
Flume Experiments ◽  
Wave Flume ◽  
Scale Models ◽  
Damage Data ◽  
Scour Protection

This paper presents a series of large-scale wave flume experiments on the scour protection damage around a monopile under combined waves and current conditions with model scales of 1:16.67 and 1:8.33. The main objective is to compare the damage data obtained from these large-scale models with existing monopile scour protection design approaches, which were proposed based on small scale wave flume experiments, and to study the applicability of the existing approaches. The static stability (onset of motion and bed shear stress) and the dynamic stability (three-dimensional damage numbers) of the scour protection are investigated. Both results show that the existing design approaches can be conservative when applied to large scale models, which highlights the need of further investigations on scale and model effects. In addition, this paper also analyses the scour protection damage depth. It is observed that damage depths of the scour protection layer under low Keulegan–Carpenter number (KC) conditions are smaller than predictions. The study provides valuable large scale experimental data for future research on the monopile scour protection design.

A Dynamic Predator–Prey Model for Fishery Resources: A Case of Lake Kasumigaura

1982 ◽  
Vol 14 (2) ◽  
pp. 225-235 ◽  
Author(s):  
Y Kitabatake
Keyword(s):  
Traditional Method ◽  
Large Scale ◽  
Prey Species ◽  
Operation Time ◽  
Lake Kasumigaura ◽  
Present Level ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Fishery Resources ◽  
Research Findings

A dynamic model for fishery resources with predator–prey relationships is constructed based on observational data and research findings for Lake Kasumigaura, Japan. The analysis of the stationary state as well as the sensitivity analysis shows that the use of diesel-powered trawling, which enables the large-scale catch of prey species in comparison with the traditional method of sailing trawling, may lead to the extinction of predator as well as prey species once the trawling efficiency in the catch of prey species is improved beyond the present level, provided that fishermen behave so as to maximize their profits subject to the restriction of operation time.

scholarly journals An alternating active-dormitive strategy enables disadvantaged prey to outcompete the perennially active prey through Parrondo’s paradox

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Tao Wen ◽  
Eugene V. Koonin ◽  
Kang Hao Cheong
Keyword(s):  
Large Scale ◽  
Active Form ◽  
Adaptive Strategy ◽  
High Energy ◽  
Predator Population ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Parrondo’S Paradox ◽  
Dormant Forms ◽  
Large Predator

Abstract Background Dormancy is widespread in nature, but while it can be an effective adaptive strategy in fluctuating environments, the dormant forms are costly due to the inability to breed and the relatively high energy consumption. We explore mathematical models of predator-prey systems, in order to assess whether dormancy can be an effective adaptive strategy to outcompete perennially active (PA) prey, even when both forms of the dormitive prey (active and dormant) are individually disadvantaged. Results We develop a dynamic population model by introducing an additional dormitive prey population to the existing predator-prey model which can be active (active form) and enter dormancy (dormant form). In this model, both forms of the dormitive prey are individually at a disadvantage compared to the PA prey and thus would go extinct due to their low growth rate, energy waste on the production of dormant prey, and the inability of the latter to grow autonomously. However, the dormitive prey can paradoxically outcompete the PA prey with superior traits and even cause its extinction by alternating between the two losing strategies. We observed higher fitness of the dormitive prey in rich environments because a large predator population in a rich environment cannot be supported by the prey without adopting an evasive strategy, that is, dormancy. In such environments, populations experience large-scale fluctuations, which can be survived by dormitive but not by PA prey. Conclusion We show that dormancy can be an effective adaptive strategy to outcompete superior prey, recapitulating the game-theoretic Parrondo’s paradox, where two losing strategies combine to achieve a winning outcome. We suggest that the species with the ability to switch between the active and dormant forms can dominate communities via competitive exclusion.

scholarly journals Predator-Prey Dynamics of Intra-Host Simian Immunodeficiency Virus Evolution Within the Untreated Host

2021 ◽  
Vol 12 ◽  
Author(s):  
Brittany Rife Magalis ◽  
Patrick Autissier ◽  
Kenneth C. Williams ◽  
Xinguang Chen ◽  
Cameron Browne ◽  
...  
Keyword(s):  
Population Size ◽  
Disease Progression ◽  
Large Scale ◽  
Immune Cell ◽  
Sequence Data ◽  
Viral Population ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Temporal Sampling ◽  
The Relationship

The dynamic nature of the SIV population during disease progression in the SIV/macaque model of AIDS and the factors responsible for its behavior have not been documented, largely owing to the lack of sufficient spatial and temporal sampling of both viral and host data from SIV-infected animals. In this study, we detail Bayesian coalescent inference of the changing collective intra-host viral effective population size (Ne) from various tissues over the course of infection and its relationship with what we demonstrate is a continuously changing immune cell repertoire within the blood. Although the relative contribution of these factors varied among hosts and time points, the adaptive immune response best explained the overall periodic dynamic behavior of the effective virus population. Data exposing the nature of the relationship between the virus and immune cell populations revealed the plausibility of an eco-evolutionary mathematical model, which was able to mimic the large-scale oscillations in Ne through virus escape from relatively few, early immunodominant responses, followed by slower escape from several subdominant and weakened immune populations. The results of this study suggest that SIV diversity within the untreated host is governed by a predator-prey relationship, wherein differing phases of infection are the result of adaptation in response to varying immune responses. Previous investigations into viral population dynamics using sequence data have focused on single estimates of the effective viral population size (Ne) or point estimates over sparse sampling data to provide insight into the precise impact of immune selection on virus adaptive behavior. Herein, we describe the use of the coalescent phylogenetic frame- work to estimate the relative changes in Ne over time in order to quantify the relationship with empirical data on the dynamic immune composition of the host. This relationship has allowed us to expand on earlier simulations to build a predator-prey model that explains the deterministic behavior of the virus over the course of disease progression. We show that sequential viral adaptation can occur in response to phases of varying immune pressure, providing a broader picture of the viral response throughout the entire course of progression to AIDS.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

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