Johnny Wei-Bing Lin

Influence of a stochastic moist convective parameterization on tropical climate variability

Convective parameterizations used in general circulation models (GCMs) generally only simulate the mean or first-order moment of convective ensembles and do not explicitly include higher-order moments. The influence of including unresolved higher-order moments is investigated using a simple stochastic convective parameterization that includes a random contribution to the convective available potential energy (CAPE) in the deep convective scheme. Impacts are tested in an tropical atmospheric model of intermediate complexity. Adding convective noise noticeably affects tropical intraseasonal variability, suggesting inclusion of such noise in GCMs might be beneficial. Model response to the noise is sensitive not only to the noise amplitude, but also to such particulars of the stochastic parameterization as autocorrelation time.

Rethinking convective quasi-equilibrium: observational constraints for stochastic convective schemes in climate models

Convective quasi-equilibrium (QE) has for several decades stood as a key postulate for parametrization of the impacts of moist convection at small scales upon the large-scale flow. Departures from QE have motivated stochastic convective parametrization, which in its early stages may be viewed as a sensitivity study. Introducing plausible stochastic terms to modify the existing convective parametrizations can have substantial impact, but, as for so many aspects of convective parametrization, the results are sensitive to details of the assumed processes. We present observational results aimed at helping to constrain convection schemes, with implications for each of conventional, stochastic or ‘superparametrization’ schemes. The original vision of QE due to Arakawa fares well as a leading approximation, but with a number of updates. Some, like the imperfect connection between the boundary layer and the free troposphere, and the importance of free-tropospheric moisture to buoyancy, are quantitatively important but lie within the framework of ensemble-average convection slaved to the large scale. Observations of critical phenomena associated with a continuous phase transition for precipitation as a function of water vapour and temperature suggest a more substantial revision. While the systems attraction to the critical point is predicted by QE, several fundamental properties of the transition, including high precipitation variance in the critical region, need to be added to the theory. Long-range correlations imply that this variance does not reduce quickly under spatial averaging; scaling associated with this spatial averaging has potential implications for superparametrization. Long tails of the distribution of water vapour create relatively frequent excursions above criticality with associated strong precipitation events.

Considerations for Stochastic Convective Parameterization

Convective parameterizations in general circulation models (GCMs) generally only aim to simulate the mean or first-order moment of convection; higher moments associated with subgrid variability are not explicitly considered. In this study, an empirically based stochastic convective parameterization is developed that uses an assumed mixed lognormal distribution of rainfall, tuned with parameter values derived from observations, to control selected nonmean statistical properties of convection. Testing of this stochastic convective parameterization reveals that large-scale model dynamics interacts heavily with the convective parameterization, in ways such that the resulting output is fundamentally different from the input. This suggests stochastic parameterizations cannot be calibrated outside of a model’s dynamical framework. Implications are discussed for the relative merits of the empirical approach versus another approach that introduces the stochastic process within the framework of the convective parameterization. Inclusion of the variance arising from unresolved scales by stochastic parameterization of convection is found to have a substantial impact upon atmospheric variability in the Tropics, including intraseasonal and longer timescales.

Maintenance of Tropical Intraseasonal Variability: Impact of Evaporation–Wind Feedback and Midlatitude Storms

An intraseasonal tropical oscillation with a period of 20‐80 days is simulated in the Neelin‐Zeng QuasiEquilibrium Tropical Circulation Model. This model is an intermediate-level atmospheric model that includes primitive equation nonlinearity, radiative‐convective feedbacks, a simple land model with soil moisture, and a Betts‐Miller-type moist convective adjustment parameterization. Vertical temperature and moisture structures in the model are based on quasi-equilibrium profiles taken from deep convective regions. The tropical intraseasonal variability is reasonably broadband. The eastward propagating 20‐80-day variability is dominated by zonal wavenumber 1, shows features similar to an irregular Madden‐Julian oscillation (MJO), and exhibits amplitude and phase speeds that vary both seasonally and between events. At higher wavenumbers, the model has a distinction between the low-frequency MJO-like band and the moist Kelvin wave band, similar to that found in observations. In the model, it is conjectured that this arises by interaction of the wavenumber-1 moist Kelvin wave with the zonally asymmetric basic state. Experiments using climatological sea surface temperature forcing are conducted using this model to examine the effects of evaporation‐wind feedback and extratropical excitation on the maintenance of intraseasonal variability, with particular attention paid to the low wavenumber mode in the 20‐80-day band. These experiments indicate that evaporation‐wind feedback partially organizes this intraseasonal variability by reducing damping, but it is not by itself sufficient to sustain this oscillation for the most realistic parameters. Excitation by extratropical variability is a major source of energy for the intraseasonal variability in this model. When midlatitude storms are suppressed, tropical intraseasonal variability is nearly eliminated. However, the eastward propagating intraseasonal signal appears most clearly when midlatitude excitation is aided by the evaporation‐wind feedback.

Patterns of Intimate Partner Violence: a study of female victims in Malawi

Abstract: Background: The term “intimate partner violence” (IPV) encompasses physical, sexual and psychological violence, or any combination of these acts, and globally is the most common type of violence against women. This study aims to examine the lifetime prevalence of different types of intimate partner violence (IPV) among Malawi women ages 15 to 49, and its association with age, education, and living in rural versus urban areas. Methods: Data was obtained from a cross-sectional study of data as part of the 2004 Malawi Demographic and Health Survey. Women were eligible for the study if they met the following criteria: 1) lived in one of the 15,041 households randomly selected from 522 rural and urban clusters located in 10 large districts of Malawi; 2) were married or cohabitating; and 3) were between the ages of 15 and 49 years. Consenting, eligible women responded to a comprehensive questionnaire covering demographic factors, health issues, as well as items related to physical, emotional and sexual IPV. To assess bivariate associations, chi-squared tests and multivariate logistic regressions were conducted. Results: Among the 8291 respondents, 13% reported emotional violence; 20% reported being pushed, shaken, slapped or punched; 3% reported experiencing severe violence, such as being strangled or burned, threatened with a knife, gun or with another weapon; and 13% reported sexual violence. Data showed women ages 15 to 19 were significantly less likely to report emotional IPV, women ages 25 to 29 were significantly more likely to report being pushed or shaken, slapped or punched (OR 1.35; CI: 1.05-1.73), and women ages 30 to 34 were significantly more likely to report sexual IPV, compared to women ages 45 to 49 (OR 1.40; CI: 1.03-1.90). Finally, women who had no ability to read were less likely to report sexual IPV than their counterparts who could read a full sentence (OR 0.76; CI: 0.66-0.87). Conclusions: The prevalence of different types of IPV in Malawi appears slightly lower than that reported for other countries in sub-Saharan Africa. Further studies are needed to assess the attitudes and behaviors of Malawi women towards acceptability and justification of IPV as well as their willingness to disclose it.

A Third Moment Adjusted Test Statistic for Small Sample Factor Analysis.

Goodness-of-fit testing in factor analysis is based on the assumption that the test statistic is asymptotically chi-square, but this property may not hold in small samples even when the factors and errors are normally distributed in the population. Robust methods such as Brownes (1984) asymptotically distribution-free method and Satorra Bentlers (1988, 1994) mean scaling statistic were developed under the presumption of nonnormality in the factors and errors. This article finds new application to the case where factors and errors are normally distributed in the population but the skewness of the obtained test statistic is still high due to sampling error in the observed indicators. An extension of Satorra Bentlers statistic is proposed that not only scales the mean but also adjusts the degrees of freedom based on the skewness of the obtained test statistic in order to improve its robustness under small samples. A simple simulation study shows that this third moment adjusted statistic asymptotically performs on par with previously proposed methods and at a very small sample size offers superior Type I error rates under a properly specified model. Data from Mardia, Kent, and Bibbys (1980) study of students tested for their ability in 5 content areas that were either open or closed book were used to illustrate the real-world performance of this statistic.

Type of alcohol drink and exposure to violence: an emergency department study.

We compared the prevalence of exposure to violence across different types of alcohol consumed and the association between the type of alcohol consumed and exposure to violence. A cross-sectional analysis of data collected from a sample of 295 Emergency Department (ED) patients identified as having an alcohol problem. Outcome measure include exposure to violence, and the main study predictor was “type of alcoholic drink” including: malt liquor beer (MLB), regular beer, wine cooler, wine, fortified wine or hard liquor. Using logistic regression analysis, ED patients who drank MLB in combination with other types of alcohol increased their odds of being both threatened and physically attacked by 8.5 compared to ED patients who drank other types of alcohol. Being female increased the odds of being both threatened and physically attacked by 2.5 and using illicit drugs increased the odds by 3.8. Analysis of covariance and estimated marginal means revealed that ED patients who only drank MLB had a higher exposure to violence compared to non-MLB drinkers, and that female illicit drug users who drank MLB in combination with other types of alcohol had the highest exposure to violence. MLB was identified as a predictor of the amount of exposure to violence and in particular, that the use of malt liquor beer in combination with other types of alcohol increased the risk of being both threatened and physically attacked. Implications for ED and community interventions are suggested.

Chapter 15 - Climate and Variability in the First Quasi-Equilibrium Tropical Circulation Model

This chapter focuses on taking quasi-equilibrium thinking into the realm of quantitative simulation. The climate and variability in the first quasi-equilibrium tropical circulation model (QTCM) is described. The QTCM is a new class of model for the tropical circulation that directly exploits constraints placed on the flow by deep convection, as represented by quasi-equilibrium thermodynamic closures in the convective parameterization. The QTCM makes use of the analytical solutions as basis functions within the numerical model, an approach referred to as “tailored basis functions,” because the retained vertical structures are tailored to the dominant physics of interest. The simplest QTCM is chosen that adequately simulates primary features of the tropical climatology. This is termed QTCMl because it retains a single vertical structure for temperature and humidity. A sampling of the simulation for a variety of phenomena and reviewing results are further presented in the chapter. The model dynamical framework, the implementation of cloud prediction, short-wave and long-wave radiation schemes, and the land-surface scheme are also explained.

Reply [to “Comment on ‘Teaching evolution, the Kansas School Board of Education, and the democratization of science’” The causes of anti-science views]

I thank R. Stephen White for responding to my Eos Forum article and appreciate the opportunity to have a dialogue with him regarding these issues. He argues that populism is not the primary cause of anti-science thinking. Rather, public sentiment toward science is one of implicit acceptance. Anti-science thinking and actions are cultural anomalies, possibly the result of conservative political activism, religious schooling, or lack of intellectual rigor.