Stochastic Nature of Physical Parameterizations in Ensemble Prediction: A Stochastic Convection Approach

Abstract In this paper it is argued that ensemble prediction systems can be devised in such a way that physical parameterizations of subgrid-scale motions are utilized in a stochastic manner, rather than in a deterministic way as is typically done. This can be achieved within the context of current physical parameterization schemes in weather and climate prediction models. Parameterizations are typically used to predict the evolution of grid-mean quantities because of unresolved subgrid-scale processes. However, parameterizations can also provide estimates of higher moments that could be used to constrain the random determination of the future state of a certain variable. The general equations used to estimate the variance of a generic variable are briefly discussed, and a simplified algorithm for a stochastic moist convection parameterization is proposed as a preliminary attempt. Results from the implementation of this stochastic convection scheme in the Navy Operational Global Atmospheric Prediction System (NOGAPS) ensemble are presented. It is shown that this method is able to generate substantial tropical perturbations that grow and "migrate" to the midlatitudes as forecast time progresses while moving from the small scales where the perturbations are forced to the larger synoptic scales. This stochastic convection method is able to produce substantial ensemble spread in the Tropics when compared with results from ensembles created from initial-condition perturbations. Although smaller, there is still a sizeable impact of the stochastic convection method in terms of ensemble spread in the extratropics. Preliminary simulations with initial-condition and stochastic convection perturbations together in the same ensemble system show a promising increase in ensemble spread and a decrease in the number of outliers in the Tropics

Impact of Stochastic Convection on the Ensemble Transform

Abstract The impact of stochastic convection on ensembles produced using the ensemble transform (ET) initial perturbation scheme is examined. This note compares the behavior of ensemble forecasts based only on initial ET perturbations with the behavior of ensemble forecasts based on the ET initial perturbations and forecasts that include stochastic convection. It is illustrated that despite the fact that stochastic convection occurs only after the forecast integrations have started, it induces changes in the initial perturbations as well. This is because the ET is a "cycling" scheme, in which previous short-term forecasts are used to produce the initial perturbations for the current forecast. The stochastic convection scheme induces rapid perturbation growth in regions where convection is active, primarily in the tropics. When combined with the ET scheme, this results in larger initial perturbation variance in the tropics, and, because of a global constraint on total initial perturbation variance, smaller initial perturbation variance in the extratropics. Thus, the inclusion of stochastic convection helps to mitigate a problem found in the practical implementation of the ET, namely, that of too little initial variance in the tropics and too much in the extratropics. Various skill scores show that stochastic convection improves ensemble performance in the tropics, with little impact to modest improvement in the extratropics. Experiments performed using the initial perturbations from the control ensemble run but forecast integrations using the stochastic convection scheme indicate that the improved performance of the stochastic convection ensemble at early forecast times is due to both "indirect" changes in the initial perturbations and "direct" changes in the forecast. At later forecast times, it appears that most of the improvement can be gained through stochastic convection alone

Economic variables that influence plantation sustainability in South Carolinas’ coastal zone

The main focus of this study is to identify the key factors that have a significant impact on plantation land conversion in South Carolina. There are many factors that are influential in determining land conversion: land characteristics, external forces, and seller’s and buyer’s characteristics. This study gives an overview of South Carolina’s coastal zone plantations between 1988 and 1998. Characteristics of these plantations such as income, land use patterns, and ownership transfer patterns were defined

A study of undergraduate students’ use of educational technologies

A qualitative study was conducted to investigate the use of technology by undergraduate students at a large public research university. Forty student interviews were conducted, 20 female students and 20 male students. Students were asked questions about their technology usage, such as: How do you use technology for academic purposes, What kinds of technological devices do you use, What software and applications do you use? Students’ were also asked questions about the usage of technology in classrooms and the university’s technology resources. The findings of this study indicate that a variety of commonly available technological tools such as email, web browsers, presentation software, learning management systems, and the internet are being used by undergraduate students and their instructors. Such usage is prevalent both inside and outside the classroom. Somewhat more specialized tools are used in different disciplines. Based on the findings of the study, the authors identify a similarity between a “gear” and technology use by faculty members and students

Comprehensive assessment of youth violence in five Caribbean countries: Gender and age differences

Differences in gender and age have been established in the context of crime, violence, and prevalence of risk and protective factors. These studies are often notable only in the Western Hemisphere. Despite growth in crime and violence in the Caribbean Community (CARICOM), relatively little understanding of violence in CARICOM member states exists. In light of these concerns, the major purposes of this study include: (1) comprehensively assessing the scope of the four behaviors (i.e., engagement, victimization, witness, and report) in relation to violence and youth’s perceptions of risk and protective factors in family and school domains, and (2) examining how they differ by youth’s gender and age. This study draws on assessment data on youth violence in five CARICOM Member States: Antigua and Barbuda, St. Kitts and Nevis, St. Lucia, Jamaica, and Trinidad and Tobago using a completed 51-item quantitative questionnaire from approximately 512 students. The results suggest that violence engagement, victimization, witness, and report significantly differed by gender and age. Male students were more likely to engage in violence, but less likely to report such violence to adults. Similarly, older students reported that they were more likely to engage in and witness violence. For risk and protective factors, female students reported significantly higher scores on domestic violence, whereas male students had higher scores on the access to drugs/weapons. Older students also tended to report higher levels of some school risk factors and lower levels of some protective factors in both family and school

'A true partner around the table?' Perceptions of how to strengthen public health's contributions to the alcohol licensing process

Introduction: There are increased opportunities for public health practitioners (PHPs) in England to shape alcohol availability and reduce harms through a statutory role in licensing processes in local government. However, how public health can effectively influence alcohol licence decision-making is little understood. Methods: A mixed methods study was conducted to identify challenges faced by PHPs and mechanisms to strengthen their role. This involved a survey of practitioners across London local authorities (n = 18) and four focus group discussions with a range of licensing stakeholders (n = 36). Results: Survey results indicated a varied picture of workload, capacity to respond to licence applications and levels of influence over decision-making among PHPs in London. Practitioners described a felt lack of status within the licence process, and difficulties using and communicating public health evidence effectively, without a health licensing objective. Strategies considered supportive included engaging with other responsible authorities and developing understanding and relationships over time. Conclusions: Against political and resource constraints at local and national government levels, pragmatic approaches for strengthening public health influence over alcohol licensing are required, including promoting relationships between stakeholders and offering opportunities for PHPs to share best practice about making effective contributions to licensing

Perioperative Laboratory Abnormalities in Gynecologic Oncology Surgical Patients

Background: Laboratory blood testing incurs financial costs and the blood draws can increase discomfort, yet minimal data exists regarding routine testing in gynecologic oncology surgical patients. Additionally, an increasing number of gynecologic oncology surgeries are performed via a laparoscopic approach. Thus, further investigation into perioperative laboratory testing for gynecologic oncology patients is warranted. An increasing number of gynecologic oncology surgeries are performed via a laparoscopic approach. Thus, further investigation into perioperative laboratory testing for gynecologic oncology patients is warranted. Objective: The aims of this study were (1) to evaluate the frequency and etiology of perioperative laboratory test abnormalities in patients undergoing laparoscopic and laparotomy surgery in a gynecologic oncology service, and (2) to establish an evidence-based algorithm to reduce unnecessary laboratory testing. Materials and Methods: A single-institution retrospective study was completed, investigating laparoscopic and laparotomic surgeries over 4 years. Information on preoperative and postoperative laboratory data, surgical parameters, perioperative interventions, and patient demographics was collected. Quality-assurance data were reviewed. Data were tabulated and analyzed using Statistical Product and Service Solutions (SPSS) version 22. A Student's t-test was used to test for group differences for continuous variables with equal variance, the Mann-Whitney?U test for continuous variables when unequal variance was detected, and Pearson's ?2 was used to investigate categorical variables of interest. p-Values 98% of patients underwent at least one preoperative and postoperative laboratory test, totaling 8060 preoperative and 5784 postoperative results. The laparoscopy group was significantly less likely to have postoperative metabolic abnormalities or to undergo perioperative blood transfusion. Patients taking an angiotensin-converting-enzyme inhibitor, angiotensin-II?receptor blocker, or diuretic were significantly more likely to have elevated creatinine preoperatively (odds ratio [OR]: 5.0; p?Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140101/1/gyn.2015.0106.pd