Statistical representation of mountain shading

International audienceShadows cast by the mountains themselves have a strong influence on the surface energy balance of mountainous regions. If the influence of shadows is to be included on sub-grid scales in a surface energy balance model, a statistical representation has to be used. Slope components calculated from digital elevation models of areas in North Wales and the French Alps are found to have double-exponential distributions. From this result, expressions are developed for the fractions of the areas that will be either self-shaded or shaded by remote topography as functions of solar elevation and time of day. These expressions are in good agreement with results from a terrain shading model. Keywords: solar radiation, topography, surface energy balance, statistical parameterisatio

Modelled sensitivity of the snow regime to topography, shrub fraction and shrub height

Recent studies show that shrubs are colonizing higher latitudes and altitudes in the Arctic. Shrubs affect the wind transport, accumulation and melt of snow, but there have been few sensitivity studies of how shrub expansion might affect snowmelt rates and timing. Here, a three-source energy balance model (3SOM), which calculates vertical and horizontal energy fluxes – thus allowing within-cell advection – between the atmosphere, snow, snow-free ground and vegetation, is introduced. The three-source structure was specifically adopted to investigate shrub–tundra processes associated with patchy snow cover that single- or two-source models fail to address. The ability of the model to simulate the snow regime of an upland tundra valley is evaluated; a blowing snow transport and sublimation model is used to simulate premelt snow distributions and 3SOM is used to simulate melt. Some success at simulating turbulent fluxes in point simulations and broad spatial pattern in distributed runs is shown even if the lack of advection between cells causes melt rates to be underestimated. The models are then used to investigate the sensitivity of the snow regime in the valley to varying shrub cover and topography. Results show that, for domain average shrub fractional cover ≤0.4, topography dominates the pre- and early melt energy budget but has little influence for higher shrub cover. The increase in domain average sensible heat fluxes and net radiation with increasing shrub cover is more marked without topography where shrubs introduce wind-induced spatial variability of snow and snow-free patches. As snowmelt evolves, differences in the energy budget between simulations with and without topography remain relatively constant and are independent of shrub cover. These results suggest that, to avoid overestimating the effect of shrub expansion on the energy budget of the Arctic, future large-scale investigations should consider wind redistribution of snow, shrub bending and emergence, and sub-grid topography as they affect the variability of snow cover

Full effects of land use change in the representative concentration pathways

Future land use change (LUC) is an important component of the IPCC representative concentration pathways (RCPs), but in these scenarios' radiative forcing targets the climate impact of LUC only includes greenhouse gases. However, climate effects due to physical changes of the land surface can be as large. Here we show the critical importance of including non-carbon impacts of LUC when considering the RCPs. Using an ensemble of climate model simulations with and without LUC, we show that the net climate effect is very different from the carbon-only effect. Despite opposite signs of LUC, all the RCPs assessed here have a small net warming from LUC because of varying biogeophysical effects, and in RCP4.5 the warming is outside of the expected variability. The afforestation in RCP4.5 decreases surface albedo, making the net global temperature anomaly over land around five times larger than RCPs 2.6 and 8.5, for around twice the amount of LUC. Consequent changes to circulation in RCP4.5 in turn reduce Arctic sea ice cover. The small net positive temperature effect from LUC could make RCP4.5's universal carbon tax, which incentivizes retaining and growing forest, counter productive with respect to climate. However, there are spatial differences in the balance of impacts, and potential climate gains would need to be assessed against other environmental aims

The effect of Staphylococcus aureus carriage in late pregnancy on antibody levels to staphylococcal toxins in cord blood and breast milk.

We investigated the effect of carriage of Staphylococcus aureus in the later stages of pregnancy on levels of antibody specific to the S. aureus toxins, staphylococcal enterotoxin B (SEB), staphylococcal enterotoxin C (SEC) and toxic shock syndrome toxin-1 (TSST-1), in cord blood and breast milk and also explored the relationship between levels of antibody in antenatal serum and cord blood. Nasopharyngeal swabs and stool samples were collected on two occasions, from 96 women, during the last 6 weeks of pregnancy. Samples were cultured and S. aureus isolates were identified. Antenatal and cord blood samples from the same women and their infants were analysed for IgG antibody to SEB, SEC and TSST-1 by enzyme-linked immunosorbent assay. Breast milk samples were analysed for IgA antibody to the same toxins. We found that S. aureus carriage in pregnancy is common and exposure to a toxin-producing isolate boosts immunity. Over 89% of women and infants have some protective antibody to the toxins, and antitoxin IgG levels are higher in cord blood samples compared with antenatal samples. Levels of cord blood IgG and breast milk IgA specific for the staphylococcal toxins vary. Some infants lack protection and could be at risk of toxin-induced disease

Will fire danger be reduced by using Solar Radiation Management to limit global warming to 1.5°C compared to 2.0°C

This is the author accepted manuscript. The final version is available from American Geophysical Union (AGU) via the DOI in this record.The commitment to limit warming to 1.5°C as set out in the Paris Agreement is widely regarded as ambitious and challenging. It has been proposed that reaching this target may require a number of actions, which could include some form of carbon removal or Solar Radiation Management in addition to strong emission reductions. Here we assess one theoretical solution using Solar Radiation Management to limit global mean warming to 1.5°C above pre‐industrial temperatures, and use the McArthur fire danger index to evaluate the change in fire danger. The results show that globally fire danger is reduced in most areas when temperatures are limited to 1.5°C compared to 2.0°C. The number of days where fire danger is ‘high’ or above is reduced by up to 30 days per year on average, although there are regional variations. In certain regions, fire danger is increased, experiencing 31 more days above ‘high’ fire danger.This work was supported by the European Commission‟s 7th Framework Programme (EU/FP7) under Grant Agreement 603864 (HELIX), and the Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101)

Older adults' experiences of internet-based vestibular rehabilitation for dizziness: A longitudinal study.

Objective Factors influencing engagement with self-managed rehabilitation are not well understood, but evidence suggests they may change over time. Despite increasing digitalisation of self-managed interventions, little is known about the role of internet-based interventions in patients’ experiences of self-directed rehabilitation. This longitudinal qualitative study investigated individuals’ on-going experiences of internet-guided, self-managed rehabilitation within the context of rehabilitation for dizziness. Methods Eighteen adults aged fifty and over who experienced dizziness used the ‘Balance Retraining’ internet intervention for six weeks. Participants took part in semi-structured telephone interviews at two week intervals to explore their experiences. Data were inductively thematically analysed. Results The internet intervention was reported to facilitate engagement with rehabilitation exercises, providing motivation to continue through symptom reduction and simple but helpful strategies. It was perceived as informative, reassuring, visually pleasing and easy to use. Barriers to engagement included practicalities, symptoms, and doubts about exercise efficacy. Participants’ perceptions did not always remain consistent over time. Conclusion The internet intervention may be a feasible method of supporting self-managed vestibular rehabilitation. More generally, longitudinal findings suggest that appearance-related perceptions of online interventions may be especially important for initial engagement. Furthermore, intervention features targeting self-efficacy seem important in overcoming barriers to engagement

Airmass analysis of the processes driving the progression of the Indian summer monsoon

The Indian summer monsoon is a vital source of water and a cause of severe impacts for more than a billion people in the Indian subcontinent. The INCOMPASS project investigates the mechanisms driving its onset and progression through an observational field campaign supplemented by high‐resolution numerical simulations for the 2016 season using UK Met Office models. A 4.4 km resolution convection‐permitting limited‐area model simulation (driven at its boundaries by a daily‐initialised global model) is used in this study, and verified against observations, along with short‐lead‐time operational global forecasts. These data show that the monsoon progression towards northwest India in June 2016 is a non‐steady process, modulated by the interaction between moist low‐level southwesterly flow from the Arabian Sea and a northwesterly incursion of descending dry air from western and central Asia. The location and extent of these two flows are closely linked to midlatitude dynamics, through the southward propagation of potential vorticity streamers and the associated formation of cyclonic circulations in the region where the two airmasses interact. Particular focus is devoted to the use of Lagrangian trajectories to characterise the evolution of the airstreams and complement the Eulerian monsoon progression analysis. The trajectories confirm that the interaction of the two airstreams is a primary driver of the general moistening of the troposphere associated with monsoon progression. They also indicate the occurrence of local diabatic processes along the airstreams, such as turbulent mixing and local evaporation from the Arabian Sea, in addition to moisture transport from remote sources. In summary, this combined Eulerian–Lagrangian analysis reveals the non‐steady nature of monsoon progression towards northwest India. This process is driven by the interaction of different airmasses and influenced by a synergy of factors on a variety of scales, such as midlatitude dynamics, transient weather systems and local diabatic processes

The Met Office Unified Model Global Atmosphere 7.0/7.1 and JULES Global Land 7.0 configurations

We describe Global Atmosphere 7.0 and GlobalLand 7.0 (GA7.0/GL7.0), the latest science configurations of the Met Office Unified Model (UM) and the Joint UK Land Environment Simulator (JULES) land surface model developed for use across weather and climate timescales. GA7.0 and GL7.0 include incremental developments and targeted improvements that, between them, address four critical errors identified in previous configurations: excessive precipitation biases over India, warm and moist biases in the tropical tropopause layer (TTL), a source of energy non-conservation in the advection scheme and excessive surface radiation biases over the Southern Ocean. They also include two new parametrisations, namely the UK Chemistry and Aerosol(UKCA) GLOMAP-mode (Global Model of Aerosol Processes) aerosol scheme and the JULES multi-layer snow scheme, which improve the fidelity of the simulation and were required for inclusion in the Global Atmosphere/Global Land configurations ahead of the 6th Coupled Model Inter-comparison Project (CMIP6).In addition, we describe the GA7.1 branch configuration, which reduces an overly negative anthropogenic aerosol effective radiative forcing (ERF) in GA7.0 whilst maintaining the quality of simulations of the present-day climate. GA7.1/GL7.0 will form the physical atmosphere/land component in the HadGEM3–GC3.1 and UKESM1 climate model submissions to the CMIP6