Inhomogeneities of stratocumulus liquid water

There is a growing body of observational evidence on inhomogeneous cloud structure, most recently from the extensive measurements of the FIRE field program. Knowledge of cloud structure is important because it strongly influences the cloud radiative properties, one of the major factors in determining the global energy balance. Current atmospheric circulation models use plane-parallel radiation, so that the liquid water in each gridbox is assumed to be uniform, which gives an unrealistically large albedo. In reality cloud liquid water occupies only a subset of each gridbox, greatly reducing the mean albedo. If future climate models are to treat the hydrological cycle in a manner consistent with energy balance, a better treatment of cloud liquid is needed. FIRE concentrated upon two cloud types of special interest: cirrus and marine stratocumulus. Cirrus tend to be high and optically thin, thus reducing the effective radiative temperature without increasing the albedo significantly, leading to an enhanced greenhouse heating. In contrast, marine stratocumulus are low and optically thick, thus producing a large increase in reflected radiation with a small change in emitted radiation, giving a net cooling which could potentially mitigate the expected greenhouse warming. The FIRE measurements in California stratocumulus during June and July of 1987 show variations in cloud liquid water on all scales. Such variations are associated with inhomogeneous entrainment, in which entrained dry air, rather than mixing uniformly with cloudy air, remains intact in blobs of all sizes, which decay only slowly by invasion of cloudy air. Two important stratocumulus observations are described, followed by a simple fractal model which reproduces these properties, and finally, the model radiative properties are discussed

The Impact of Parental Psychological Control on College Students’ Relational Aggression and Friendship Quality

The present study investigated the relationships between parental psychological control and college students’ relational aggression and friendship quality. Based on previous research, it was expected that parents’ use of psychological control would be associated with students’ increased use of relational aggression with peers and lower friendship quality. Students completed a series of survey measures assessing their mothers’ and fathers’ use of psychological control, behavioral control, and warmth/acceptance. Students also completed a series of survey measures assessing their friendship quality, social skills, relational aggression, self-esteem, and social desirability. The study’s findings revealed that parental psychological control was associated with and predicted students’ increased use of relational aggression with peers. Parental psychological control was also associated with students’ lower friendship quality. However, parents’ use of psychological control did not predict students’ friendship quality after accounting for the influence of students’ personal and peer relationship variables. This finding suggests that characteristics of peer relationships may play a larger role than parenting behaviors in shaping college students’ friendships. The study also found that students who displayed higher levels of relational aggression had lower quality friendships. Other findings revealed that the relationship between parental psychological control and students’ friendship quality can be partially explained by students’ use of relational aggression with peers. Students’ friendship quality can also help to explain the influence of parental psychological control on students’ relational aggression. In addition, the study found that combinations of parenting behaviors were more informative predictors of students’ relational aggression and friendship quality than psychological control alone. Finally, this study revealed the importance of assessing participants’ social desirability when measuring sensitive personal qualities such as relational aggression, friendship quality, and self-esteem. Overall, this study contributes to the field of research on parental psychological control by revealing its effects on college students’ relational aggression and friendship quality

Public Procurement Policy: Implications for Theory and Practice

This paper proposes a conceptual framework for the study of public procurement policy. It reviews policy-related writings by public procurement scholars and assesses these works from the perspective of their contributions to generalized understandings of public procurement policy. Selected tools and concepts from the policy sciences are applied to propose a model to illuminate unique aspects of public procurement policy in ways that will facilitate its study. The paper concludes by discussing some recent actions, trends, and issues from the U.S defense procurement sector in terms of the framework. Models such as the one proposed in this paper will contribute to enhanced approaches to procurement policy analysis by scholars, as well as to informed and sophisticated policy implementation by practitioners

Arizona Prospector

https://digitalcommons.library.umaine.edu/mmb-vp/3024/thumbnail.jp

A Universal Property of Axonal and Dendritic Arbors

SummaryAxonal and dendritic arbors can be characterized statistically by their spatial density function, a function that specifies the probability of finding a branch of a particular arbor at each point in a neural circuit. Based on an analysis of over a thousand arbors from many neuron types in various species, we have discovered an unexpected simplicity in arbor structure: all of the arbors we have examined, both axonal and dendritic, can be described by a Gaussian density function truncated at about two standard deviations. Because all arbors are characterized by density functions with this single functional form, only four parameters are required to specify an arbor's size and shape: the total length of its branches and the standard deviations of the Gaussian in three orthogonal directions. This simplicity in arbor structure can have implications for the developmental wiring of neural circuits

Windowed and Wavelet Analysis of Marine Stratocumulus Cloud Inhomogeneity

To improve radiative transfer calculations for inhomogeneous clouds, a consistent means of modeling inhomogeneity is needed. One current method of modeling cloud inhomogeneity is through the use of fractal parameters. This method is based on the supposition that cloud inhomogeneity over a large range of scales is related. An analysis technique named wavelet analysis provides a means of studying the multiscale nature of cloud inhomogeneity. In this paper, the authors discuss the analysis and modeling of cloud inhomogeneity through the use of wavelet analysis. Wavelet analysis as well as other windowed analysis techniques are used to study liquid water path (LWP) measurements obtained during the marine stratocumulus phase of the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment. Statistics obtained using analysis windows, which are translated to span the LWP dataset, are used to study the local (small scale) properties of the cloud field as well as their time dependence. The LWP data are transformed onto an orthogonal wavelet basis that represents the data as a number of times series. Each of these time series lies within a frequency band and has a mean frequency that is half the frequency of the previous band. Wavelet analysis combined with translated analysis windows reveals that the local standard deviation of each frequency band is correlated with the local standard deviation of the other frequency bands. The ratio between the standard deviation of adjacent frequency bands is 0.9 and remains constant with respect to time. This ratio defined as the variance coupling parameter is applicable to all of the frequency bands studied and appears to be related to the slope of the data's power spectrum. Similar analyses are performed on two cloud inhomogeneity models, which use fractal-based concepts to introduce inhomogeneity into a uniform cloud field. The bounded cascade model does this by iteratively redistributing LWP at each scale using the value of the local mean. This model is reformulated into a wavelet multiresolution framework, thereby presenting a number of variants of the bounded cascade model. One variant introduced in this paper is the 'variance coupled model,' which redistributes LWP using the local standard deviation and the variance coupling parameter. While the bounded cascade model provides an elegant two- parameter model for generating cloud inhomogeneity, the multiresolution framework provides more flexibility at the expense of model complexity. Comparisons are made with the results from the LWP data analysis to demonstrate both the strengths and weaknesses of these models