Modifications to the representation of subgrid mixing in kilometre‐scale versions of the Unified Model

A mixed subgrid scheme for scalars and momentum fluxes in cloud‐resolving models which includes an extra subgrid vertical flux, referred to as “the Leonard term”, that accounts for the tilting of horizontal flux into the vertical by horizontal gradients in vertical velocity was proposed by Moeng. Here we describe the implementation of the Leonard term in the current subgrid mixing scheme used in kilometre‐scale versions of the Met Office's Unified Model. We present results that show that including this extra term in the Met Office's 1.5 km grid length UK model reduces the domain‐average precipitation by reducing the number of grid points with rainfall rates greater than 4 mm/hr‐1, which are over‐represented by the model. Increasing the magnitude of the Leonard terms further decreases the occurrence of the heaviest rainfall rates

A framework for convection and boundary layer parameterization derived from conditional filtering

A new theoretical framework is derived for parameterization of subgrid physical processes in atmospheric models; the application to parameterization of convection and boundary layer fluxes is a particular focus. The derivation is based on conditional filtering, which uses a set of quasi-Lagrangian labels to pick out different regions of the fluid, such as convective updrafts and environment, before applying a spatial filter. This results in a set of coupled prognostic equations for the different fluid components, including subfilter-scale flux terms and entrainment/detrainment terms. The framework can accommodate different types of approaches to parameterization, such as local turbulence approaches and mass-flux approaches. It provides a natural way to distinguish between local and nonlocal transport processes, and makes a clearer conceptual link to schemes based on coherent structures such as convective plumes or thermals than the straightforward application of a filter without the quasi-Lagrangian labels. The framework should facilitate the unification of different approaches to parameterization by highlighting the different approximations made, and by helping to ensure that budgets of energy, entropy, and momentum are handled consistently and without double counting. The framework also points to various ways in which traditional parameterizations might be extended, for example by including additional prognostic variables. One possibility is to allow the large-scale dynamics of all the fluid components to be handled by the dynamical core. This has the potential to improve several aspects of convection-dynamics coupling, such as dynamical memory, the location of compensating subsidence, and the propagation of convection to neighboring grid columns

The third Met Office Unified Model-JULES Regional Atmosphere and Land Configuration, RAL3

The third version of the Regional Atmosphere and Land (RAL3) science configuration is documented. Developed through international partnership, RAL configurations define settings for the Unified Model atmosphere and Joint UK Land Environment Simulator when applied across timescales with kilometre and sub-km scale model grids. The RAL3 configuration represents a major advance compared to previous versions by delivering a common science definition suitable for application to tropical and mid-latitude regions. Developments within RAL3 include the introduction of a double-moment microphysics scheme and a bi-modal cloud scheme, replacing use of a single-moment scheme and different cloud schemes for mid-latitudes and tropics in previous versions. Updates have been implemented to the boundary layer scheme and a consolidation of land model settings to be more consistent with Global Atmosphere and Land (GAL) science configurations. Physics developments aimed to address priorities for model performance improvement identified by users. This paper documents the RAL3 science configuration, including a series of iterative revisions delivered since its first release, and their characteristics. Evidence is provided from the variety of assessments of RAL3, relative to the previous version (RAL2). Collaborative development and evaluation across organisations has enabled evaluation across a range of domains, grid-spacing and timescales. The analysis indicates more realistic precipitation distributions; improved representation of clouds and of visibility; a continued trend to more realistic representation of convection; and reduced near-surface wind speeds, but a persistent cold temperature bias. Overall the convective-scale verification scores and climatological model distributions relative to observations improve for the majority of variables. Ensemble results show improvements to the spread-error relationship. User feedback from subjective assessment activities has also been positive. Differences between RAL3 revisions and RAL2 are further illustrated through process-based analysis of a convective system over the UK. The latest RAL3 configuration (RAL3.3) is therefore recommended for research, operational numerical weather prediction and climate production at km and sub-km scales

Testing of the short self-efficacy and outcome expectations

The purpose of this study was to test the reliability and validity of the short outcome expectations for exercise (SOEE) and short self-efficacy expectations for exercise (SSEE) scales in a sample of adults recruited into two exercise intervention studies for patients post stroke. A total of 157individuals, 90males (56%) and 67females (43%) with an average age of 63.7 (SD=12.3) years participated in the study. There was evidence of internal consistency for both scales based on alpha coefficients and Rasch Model testing estimates of person and item separability, evidence of test re-test reliability with no change in scores over a 6-week period, and some support of reliability based on R2 estimates. There was evidence of validity of the measures based on confirmatory factor analysis using structural equation modeling and Rasch measurement model testing, and convergent validity testing. There was some evidence of convergent validity based on a statistically significant relationship between self-efficacy and outcome expectations, and both of these measures with physical health status. The study provided some preliminary evidence for the reliability and validity of the SSEE and SOEE when used with adult stroke patients, and suggested revisions for subsequent use of these measures are provide

Cardiovascular risk in survivors of stroke

Background: stroke survivors are at significant risk for recurrent stroke and cardiovascular disease. Inadequately managed modifiable risk factors increase the threat of recurrent stroke, development of new comorbidities, and double the risk of premature mortality. The purpose of this study was to determine the prevalence of modifiable cardiovascular risk factors in stroke survivors who completed a research screening evaluation for entry into exercise rehabilitation studies. The sample collected between January 2001 and June 2005 evaluated 364 community-dwelling men and women aged 34 to 88 years living in Baltimore, Maryland.Methods: each participant’s risk profile was evaluated from data obtained during a medical history and physical examination and from laboratory analysis of a fasting blood sample. Current practice guidelines were used to define risk categories.Results: ninety-nine percent of participants had at least one suboptimally controlled risk factor. Ninety-one percent had two or more concurrent risk factors inadequately treated. Eighty percent of the participants had prehypertension or hypertension, 67% were overweight or obese, 60% had suboptimal low-density lipoprotein, 45% had impaired fasting glucose, 34% had low high-density lipoprotein, and 14% were current smokers, while reportedly receiving routine medical care.Conclusions: these findings confirm that cardiovascular risk factors remain inadequately managed in stroke survivors, increasing the chance for repeat stroke and cardiovascular event. Systematic assessment of this vulnerable population is imperative at every healthcare encounte

Confronting the Convective Gray Zone in the Global Configuration of the Met Office Unified Model

Abstract In atmospheric models with kilometer‐scale grids the resolution approaches the scale of convection. As a consequence the most energetic eddies in the atmosphere are partially resolved and partially unresolved. The modeling challenge to represent convection partially explicitly and partially as a subgrid process is called the convective gray zone problem. The gray zone issue has previously been discussed in the context of regional models, but the evolution in regional models is constrained by the lateral boundary conditions. Here we explore the convective gray zone starting from a defined global configuration of the Met Office Unified Model using initialized forecasts and comparing different model formulations to observations. The focus is on convection and turbulence, but some aspects of the model dynamics are also considered. The global model is run at nominal 5 km resolution and thus contributions from both resolved and subgrid turbulent and convective fluxes are non‐negligible. The main conclusion is that in the present assessment, the configurations which include scale‐aware turbulence and a carefully reduced and simplified mass‐flux convection scheme outperform both the configuration with fully parameterized convection as well as a configuration in which the subgrid convection parameterization is switched off completely. The results are more conclusive with regard to convective organization and tropical variability than extratropical predictability. The present study thus endorses the strategy to further develop scale‐aware physics schemes and to pursue an operational implementation of the global 5 km‐resolution model to be used alongside other ensemble forecasts to allow researchers and forecasters to further assess these simulations