bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation of the diurnal cycle of marine stratocumulus during FIRE—An LES and SCM modelling study
Authors: Chlond Andreas , Müller Frank , Sednev Igor 
Published: February 2005

AbstractAs part of the European Project on Cloud Systems in Climate Models (EUROCS), the stratocumulus‐topped boundary layer has been simulated using the Max Planck Institute Large‐Eddy Simulation (LES) model and the European Centre Hamburg Version Single Column Model (ECHAM–SCM). We have addressed the full diurnal cycle of stratocumulus off the coast of California based on observations of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE). The results of the LES model demonstrate that the model is capable of reproducing the observed diurnal cycle of the boundary‐layer structure reasonably well. In particular, the LES model reproduces the distinct diurnal variation in liquid‐water path and of turbulence profiles due to the forcing imposed by the short‐wave heating of the cloud layer. In addition, we have examined the sensitivity of our LES results with respect to the assumed values of various external environmental conditions. We found that the largest contribution to the variance of the LES‐derived data products is due to the uncertainties in the cloud‐top jumps of liquid‐water potential temperature and total‐water mixing ratio and to the net radiative forcing.To evaluate the quality of the representation of stratocumulus in a general circulation model, results from the standard ECHAM–SCM are contrasted with diagnostics from LES simulations. Results of the standard ECHAM–SCM reveal the following deficiencies: values of the liquid‐water path are too low, and unrealistically large levels of turbulent kinetic energy within the cloud layer are due to a numerical instability arising from a decoupling of radiative and diffusive processes. Based on these findings, the SCM has been revised. The modifications include the vertical advection scheme, the numerical treatment of diffusion and radiation, and the combination of the 1.5‐order turbulent closure model with an explicit entrainment closure at the boundary‐layer top in combination with a front tracking/capturing method. It is demonstrated that, with these modifications, the revised SCM produces a fair simulation of the diurnal cycle of the stratocumulus‐topped boundary layer which is significantly improved compared to the one performed with the standard SCM. Copyright © 2004 Royal Meteorological Society
Moisture–convection feedback in the tropics
Authors: Grabowski W. W. , Moncrieff M. W. 
Published: February 2005

AbstractThis paper discusses the large‐scale moisture–convection feedback in the tropics, where spatial fluctuations of deep convection cause perturbations of free‐tropospheric moisture which, in turn, affect the spatial distribution of deep convection. A simple heuristic argument using the timescale of free‐tropospheric humidity change explains why moisture–convection feedback is particularly relevant for tropical intraseasonal oscillations.The large‐scale dynamical context for moisture–convection feedback is investigated in idealized rotating constant‐sea‐surface‐temperature (‘tropics everywhere’) aquaplanet using cloud‐resolving convection parametrization (CRCP; super‐parametrization) and a traditional convective parametrization (the Emanuel scheme). The large‐scale organization of convection within the equatorial waveguide takes the form of MJO‐like (Madden–Julian Oscillation) coherent structures. First, CRCP simulations are performed in which development of large‐scale free‐tropospheric moisture perturbations is artificially suppressed using relaxation with a timescale of one day. As in previous simulations where much shorter relaxation timescale was used, MJO‐like coherences do not develop and, if already present, they disintegrate rapidly. Second, CRCP simulations that start from planetary‐scale moisture perturbation in the free troposphere are conducted. The ensuing large‐scale velocity perturbations have e‐folding times of five and seven days, respectively, for interactive and prescribed radiation simulations. This supports the conjecture that interactive radiation enhances moisture–convection feedback; an enhanced large‐scale circulation results from differences in radiative cooling between areas having enhanced and suppressed convectively‐generated moisture and cloudiness. Additional support for the role of moisture–convection feedback in intraseasonal oscillations is seen in simulations that apply the Emanuel scheme. The standard configuration of the Emanuel scheme is insensitive to free‐tropospheric humidity and results in weak MJO‐like coherences. A simple modification of the Emanuel scheme that enhances its sensitivity to free‐tropospheric humidity dramatically improves the simulated MJO‐like coherences. Copyright © 2004 Royal Meteorological Society
The impacts of spatial variability on the development of convection
Authors: Stirling A. J. , Petch J. C. 
Published: February 2005

AbstractA cloud‐resolving model is used to investigate the impact of spatial variability in moisture and temperature on the timing of deep convection over land. Using a simulation of a diurnal cycle of convection, horizontal variations in moisture and temperature are shown to have a significant impact on the development of convection. The onset of deep convection can change by several hours and total rainfall amounts can change by up to 70%.Further sensitivity studies are carried out to investigate the impacts of vertical location, horizontal scale and magnitude of the variability. It is shown that variability of relative humidity in the boundary layer has the most significant impact and this is linked to its strong influence on local convective inhibition. Horizontal scales larger than 10 km are shown to have the strongest influence on the timing of convection, and the strongest amplitude of convectively generated fluctuations is shown to be on these larger scales. © Royal Meteorological Society, 2004. J. C. Petch's contribution is Crown copyright
Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case
Authors: Duynkerke Peter G. , de Roode Stephan R. , van Zanten Margreet C. , Calvo Javier , Cuxart Joan , Cheinet Sylvain , Chlond Andreas , Grenier Hervé , Jonker Piet J. , Köhler Martin , Lenderink Geert , Lewellen David , Lappen Cara‐lyn , Lock Adrian P. , Moeng Chin‐hoh , Müller Frank , Olmeda Dolores , Piriou Jean‐marcel , Sánchez Enrique , Sednev Igor 
Published: February 2005

AbstractAs part of the European Project on Cloud Systems in Climate Models, the diurnal cycle of stratocumulus has been simulated with Large‐Eddy Simulation (LES) models and Single Column Models (SCMs). The models were initialized and compared with observations collected in marine stratocumulus in July 1987 during the First International Satellite Cloud Climatology Project Regional Experiment. The results of the six LES models are found to be in a fair agreement with the observations. They all capture the distinct diurnal variation in the cloud liquid‐water path, the turbulence profiles and clearly show a decoupled boundary layer during daytime and a vertically well‐mixed boundary layer during the night. Entrainment of relatively dry and warm air from just above the inversion into the boundary layer is the major process modifying the thermodynamic structure of the boundary layer during the night. The differences that arise in the liquid‐water path evolution can therefore be attributed mainly to differences in the entrainment rate. The mean entrainment rates computed from the LES model results are 0.58±0.08 cm s−1 and 0.36±0.03 cm s−1 for the night‐time and daytime periods, respectively. If the horizontal domain size in a LES model is enlarged, mesoscale fluctuations develop. This leads to a broader liquid‐water path distribution and a reduction of the cloud albedo.To assess the quality of the representation of stratocumulus in general‐circulation models, results from ten SCMs are compared with observations and LES results. The SCM latent and sensible heat fluxes at the surface agree fairly well with the LES results. Many of the SCMs predict a liquid‐water path which is much too low, a cloud cover smaller than unity, and cloud tops that are lower than the observations and the LES results. This results in a much larger amount of downwelling short‐wave radiation absorbed at the sea surface. Improvement of entrainment parametrizations is needed for a better representation of stratocumulus in SCMs.Observations and LES results of entrainment rates for different stratocumulus cases are compared. The observed entrainment rates in Atlantic stratocumulus clouds during the Atlantic Stratocumulus Transition Experiment (ASTEX) are larger than for the ones over the Pacific Ocean off the coast of California. Results from LES models corroborate these findings. The differences in the entrainment rate can likely be attributed to the smaller inversion jumps of the liquid‐water potential temperature for the ASTEX stratocumulus cases. © Royal Meteorological Society, 2004. A. P. Lock's contribution is Crown copyright
Improved mixing representation in Emanuel's convection scheme
Authors: Grandpeix J.‐Y. , Phillips V. , Tailleux R. 
Published: February 2005

AbstractRecent 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 of shortcomings in the way that entrainment is represented in such parametrizations. This matter was explored in the European Cloud Systems project (EUROCS) by means of an idealized humidity experiment in which the main controlling parameter is RH. In the latter study, cloud‐resolving model (CRM) experiments suggested that a shallow/deep convection transition occurs when RH crosses a threshold value that ranges from about RH=50% to RH=60%.In this paper, we seek to increase the responsiveness of Emanuel's convection scheme to RH, and to reproduce the threshold behaviour of the idealized humidity case, by replacing the original uniform probability density function (PDF) for mixing fractions by a more flexible two‐parameter bell‐shaped function that allows a wider range of behaviour. The main result is that the parameters of this PDF can be tuned to allow a regime transition to occur near a threshold value of RH≈55%. In contrast to CRM results, however, this transition is between two different regimes of deep convection rather than between a shallow and deep regime. Possible ways to obtain a shallow‐to‐deep transition with Emanuel's scheme are discussed. Copyright © 2004 Royal Meteorological Society
Cloud representation in general‐circulation models over the northern Pacific Ocean: A EUROCS intercomparison study
Authors: Siebesma A. P. , Jakob C. , Lenderink G. , Neggers R. A. J. , Teixeira J. , Van Meijgaard E. , Calvo J. , Chlond A. , Grenier H. , Jones C. , Köhler M. , Kitagawa H. , Marquet P. , Lock A. P. , Müller F. , Olmeda D. , Severijns C. 
Published: February 2005

AbstractThe EUROCS (EUROpean Cloud Systems study) project aims to improve the treatment of cloud systems in regional and global climate and weather prediction models. This paper reports an intercomparison study of cloud representation over the Pacific Ocean for nine climate and weather prediction models. The study consists of an analysis of a June/July/August 1998 period along an idealized trajectory over the Pacific Ocean that encompasses both the ascending and descending branch of the Hadley circulation. The three cloud types that are studied by EUROCS, stratocumulus, shallow cumulus and deep‐convective cloud systems, do all occur in a persistent and geographically separated way, along this trajectory.The main focus of this study is on processes related to the hydrological cycle within the Hadley circulation. These include the large‐scale dynamics (i.e. the strength of the up‐ and downwelling branches of the Hadley cell), the cloud processes (i.e. cloud cover, cloud amounts and precipitation), and the impact of these processes on the radiation budget both at the top of the atmosphere and at the ocean's surface.In order to make a quantitative assessment, special care has been taken to select reliable observational datasets. The main conclusions are that (1) almost all models strongly underpredicted both cloud cover and cloud amount in the stratocumulus regions while (2) the situation is opposite in the trade‐wind region and the tropics where cloud cover and cloud amount are overpredicted by most models. These deficiencies result in an overprediction of the downwelling surface short‐wave radiation of typically 60 W m−2 in the stratocumulus regimes and a similar underprediction of 60 W m−2 in the trade‐wind regions and in the intertropical convergence zone (ITCZ). Similar biases for the short‐wave radiation were found at the top of the atmosphere, while discrepancies in the outgoing long‐wave radiation are most pronounced in the ITCZ. © Royal Meteorological Society, 2004. A. P. Lock's contribution is Crown copyright
Competitive Reactions to Advertising and Promotion Attacks
Authors: Steenkamp Jan-Benedict E. M. , Nijs Vincent R. , Hanssens Dominique M. , Dekimpe Marnik G. 
Published: February 2005

How do competitors react to each other's price-promotion and advertising attacks? What are the reasons for the observed reaction behavior? We answer these questions by performing a large-scale empirical study on the short-run and long-run reactions to promotion and advertising shocks in over 400 consumer product categories over a four-year time span. Our results clearly show that the most predominant form of competitive response is passive in nature. When a reaction does occur, it is usually retaliatory in the same instrument, i.e., promotion attacks are countered with promotions, and advertising attacks are countered with advertising. There are very few long-run consequences of any type of reaction behavior. By linking reaction behavior to both cross- and own-effectiveness, we further demonstrate that passive behavior is often a sound strategy, while firms that do opt to retaliate often use ineffective instruments, resulting in “spoiled arms.” Accommodating behavior is observed in only a minority of cases, and often results in a missed sales opportunity when promotional support is reduced. The ultimate impact of most promotion and advertising campaigns depends primarily on the nature of consumer response, not the vigilance of competitors.
Time-Varying Competition
Authors: Sudhir K. , Chintagunta Pradeep K. , Kadiyali Vrinda 
Published: February 2005

Normative models typically suggest that prices rise in periods of high demand and cost. However, in many markets, prices fall when demand or costs rise. This inconsistency occurs because the normative models assume that competitive intensity does not change with demand and cost conditions over time. We therefore introduce the notion of time-varying competition by suggesting that it is important not only to account for the direct effect of demand and cost on prices (e.g., higher demand means higher prices), but also the indirect effect of demand and cost changes on competition (e.g., higher demand could cause more competition and, hence, lower prices). We develop a general, unified framework to empirically model the direct and indirect effects of demand and cost shifts on pricing in differentiated product markets. Our approach allows us to measure the indirect effect of multiple demand and cost drivers on competitive intensity and test predictions from alternative theories of repeated games. The empirical application is to the U.S. photographic film industry, where there are two main players, Kodak and Fuji. We find that the indirect effects are highly significant and comparable in magnitude to the direct effects. Competitive intensity is greater in periods of high demand and lower cost and is moderated by whether demand or costs are expected to grow or decline. Interestingly, we find asymmetries in the competitive responses of Kodak and Fuji. While Kodak is sensitive to demand factors, Fuji is sensitive to costs. Our results suggest that market characteristics such as observability of competitor prices can be an important determinant of how competitive intensity is affected by demand and cost conditions.
Planning Marketing-Mix Strategies in the Presence of Interaction Effects
Authors: Naik Prasad A. , Raman Kalyan , Winer Russell S. 
Published: February 2005

Companies spend millions of dollars on advertising to boost a brand's image and simultaneously spend millions of dollars on promotion that many believe calls attention to price and erodes brand equity. We believe this paradoxical situation exists because both advertising and promotion are necessary to compete effectively in dynamic markets. Consequently, brand managers need to account for interactions between marketing activities and interactions among competing brands. By recognizing interaction effects between activities, managers can consider interactivity trade-offs in planning the marketing-mix strategies. On the other hand, by recognizing interactions with competitors, managers can incorporate strategic foresight in their planning, which requires them to look forward and reason backward in making optimal decisions. Looking forward means that each brand manager anticipates how other competing brands are likely to make future decisions, and then by reasoning backward deduces one's own optimal decisions in response to the best decisions to be made by all other brands. The joint consideration of interaction effects and strategic foresight in planning marketing-mix strategies is a challenging and unsolved marketing problem, which motivates this paper. This paper investigates the problem of planning marketing mix in dynamic competitive markets. We extend the Lanchester model by incorporating interaction effects, constructing the marketing-mix algorithm that yields marketing-mix plans with strategic foresight, and developing the continuous-discrete estimation method to calibrate dynamic models of oligopoly using market data. Both the marketing-mix algorithm and the estimation method are general, so they can be applied to any other alternative model specifications for dynamic oligopoly markets. Thus, this dual methodology augments the decision-making toolkit of managers, empowering them to tackle realistic marketing problems in dynamic oligopoly markets. We illustrate the application of this dual methodology by studying the dynamic Lanchester competition across five brands in the detergents market, where each brand uses advertising and promotion to influence its own market share and the shares of competing brands. Empirically, we find that advertising and promotion not only affect the brand shares (own and competitors') but also exert interaction effects, i.e., each activity amplifies or attenuates the effectiveness of the other activity. Normatively, we find that large brands underadvertise and overspend on promotion, while small brands underadvertise and underpromote. Finally, comparative statics reveal managerial insights into how a specific brand should respond optimally to the changes in a competing brand's situation; more generally, we find evidence that competitive responsiveness is asymmetric.
A Prelaunch Diffusion Model for Evaluating Market Defense Strategies
Authors: Roberts John H. , Nelson Charles J. , Morrison Pamela D. 
Published: February 2005

This paper describes the development and application of a marketing model to help set an incumbent's defensive marketing strategy prior to a new competitor's launch. The management problem addressed is to assess the market share impact of a new entrant in the residential Australian long distance telephone call market and determine the factors that would influence its dynamics and ultimate market appeal. The paper uses probability flow models to provide a framework to generate forecasts and assess the determinants of share loss. We develop models at two levels of complexity to give both simple, robust forecasts and more detailed diagnostic analysis of the effect of marketing actions. The models are calibrated prior to the new entrant's launch, enabling preemptive marketing strategies to be put in place by the defending company. The equilibrium level of consideration of the new entrant was driven by respondents' strength of relationship with the defender and inertia, while trial was more price-based. Continued use of the defender depends on both service factors and price. The rate at which share loss eventuates is negatively related to the defender's perceived responsiveness, saving money being the only reason to switch, and risk aversion. Prelaunch model forecasts, validated six months after launch using both aggregate monthly sales data and detailed tracking surveys, are shown to closely follow the actual evolution of the market. The paper provides a closed-form multistate model of the new entrant's diffusion, a methodology for the prelaunch calibration of dynamic models in practice, and insights into defensive strategies for existing companies facing new entrants.
Comments on Competitive Responsiveness
Authors: Shugan Steven M. 
Published: February 2005

Marketing Science features many and diverse articles that analyze competitive responsiveness. Although recent Marketing Science editorials (e.g., Shugan 2002) suggest that competitive responsiveness is only a part of a comprehensive competitive marketing strategy, it remains a vital part. For that reason and many others, Marketing Science is particularly proud of this special issue edited by David J. Reibstein and Dick R. Wittink. Before introducing and vigorously applauding both the editors and authors of this excellent special issue, we emphasize that competitive responsiveness raises numerous issues, including whether one can forecast outcomes of new policies based on past observations made under old policies (i.e., the Lucas critique) and decisions regarding which variables should be considered endogenous (Shugan 2004), i.e., determined within the model. Perhaps, normative models are inherently perishable—evolution in market structure requires modifications over time. Also, although complete consistency within the world of the model is aesthetically pleasing, imposing industry-specific exogenous constraints (that might appear unrelated to the modeling assumptions) is sometimes necessary.
An ARIMA Supply Chain Model
Authors: Gilbert Kenneth 
Published: February 2005

This paper presents a multistage supply chain model that is based on Autoregressive Integrated Moving Average (ARIMA) time-series models. Given an ARIMA model of consumer demand and the lead times at each stage, it is shown that the orders and inventories at each stage are also ARIMA, and closed-form expressions for these models are given. The paper also discusses the causes of the bullwhip effect, a phenomenon in which variation in demand produces larger variations in upstream orders and inventory. This discussion reveals how different modeling can lead to different insights because they make different assumptions about the cause of the bullwhip effect. These observations are used to develop managerial insights about reducing the bullwhip effect.