86 research outputs found
CMIP5 diversity in southern westerly jet projections related to historical sea ice area; strong link to strengthening and weak link to shift
A major feature of projected changes in Southern Hemisphere climate under future scenarios of increased greenhouse gas concentrations is the poleward shift and strengthening of the main eddy-driven belt of mid-latitude near-surface westerly winds (the westerly jet). However, there is large uncertainty in projected twenty-first century westerly jet changes across different climate models.
Here the World Climate Research Programme’s Coupled Model Intercomparison Project phase 5 (CMIP5) models were evaluated to assess linkages between diversity in simulated sea ice area (SIA), Antarctic amplification and diversity in projected 21st century changes in the westerly jet following the Representative Concentration Pathway 8.5 scenario (RCP8.5). To help disentangle cause and effect in the coupled model analysis, uncoupled atmosphere-only fixed sea-surface experiments from CMIP5 were also evaluated.
It is shown that across all seasons approximately half of the variance in projected RCP8.5 jet strengthening is explained statistically by inter-model differences in simulated historical SIA, whereby CMIP5 models with larger baseline SIA exhibit more ice retreat and less jet strengthening in the future. However, links to jet shift are much weaker and only statistically significant in autumn and winter. It is suggested that a significant cross-model correlation between historical jet strength and projected strength change (r = -0.58) is, at least in part, a result of atmospherically-driven historical SIA biases, which then feed back onto the atmosphere in future projections. The results emphasize that SIA appears to act in concert with proximal changes in sea-surface temperature gradients in relation to model diversity in westerly jet projections
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Combining satellite observations and reanalysis energy transports to estimate global net surface energy fluxes 1985-2012
Two methods are developed to estimate net surface energy fluxes based upon satellite-based reconstructions of radiative fluxes at the top of atmosphere and the atmospheric energy tendencies and transports from the ERA-Interim reanalysis. Method 1 applies the mass adjusted energy divergence from ERA-Interim while method 2 estimates energy divergence based upon the net energy difference at the top of atmosphere and the surface from ERA-Interim. To optimise the surface flux and its variability over ocean, the divergences over land are constrained to match the monthly area mean surface net energy flux variability derived from a simple relationship between the surface net energy flux and the surface temperature change. The energy divergences over the oceans are then adjusted to remove an unphysical residual global mean atmospheric energy divergence. The estimated net surface energy fluxes are compared with other data sets from reanalysis and atmospheric model simulations. The spatial correlation coefficients of multi-annual means between the estimations made here and other data sets are all around 0.9. There are good agreements in area mean anomaly variability over the global ocean, but discrepancies in the trend over the eastern Pacific are apparent
The sensitivity of British weather to ocean tides
Tides in shelf seas greatly impact ocean mixing and temperature structure. Using a regional‐coupled ocean–atmosphere prediction system, at ocean coastal process and atmosphere convection permitting scales, we assess the influence of tides on British weather by comparing simulations with and without tides. In summer, when seasonal stratification is particularly sensitive to tides, the sea‐surface temperature is up to 6 K cooler in simulations with tidal mixing. Tides cool the air temperature over the sea by up to 3 K, and nearby land by up to 1.4 K. The mean air temperature across Great Britain land areas cools by 0.3 K with tides. Changes in near‐surface stability result in decreases in summer mean wind speeds over the ocean. A 6% reduction in summer precipitation is found with tides, consistent with cooler temperatures. This study has implications for climate projections since global‐coupled models typically do not include tides
Sheep Updates 2015 - Katanning
This session covers fourteen papers from different authors:
1. The Sheep Industry Business Innovation project, Bruce Mullan, Sheep Industry Development Director, Department of Agriculture and Food, Western Australia
2. Western Australian sheep stocktake, Kate Pritchett and Kimbal Curtis, Research Officers, Department of Agriculture and Food, Western Australia
3. Wool demand and supply - short term volatility, long term opportunities, Chris Wilcox, Principal of Poimena Analysis
4. Lifetime management for maternal ewes, Mike Hyder, Research Officer, Department of Agriculture and Food, Western Australia
5. National Livestock Identification System (NLIS) for sheep and goats - what is the NLIS database? Leigh Sonnermann, Biosecurity Officer, Department of Agriculture and Food, Western Australia
6. Myths, Facts and the role of animal welfare in farming, Lynne Bradshaw, president, RSPCA WA
7. Latest research and development on breech strike prevention, Geoff Lindon, Manager Productivity and Animal Welfare, AWI
8. Lamb Survival Initiative and 100% Club, Katherine Davies, Development Officer, Department of Agriculture and Food, Western Australia
9. How to boost your lamb survival, Joe Young, Sheep Consultant, R.B. Young and Son
10. Using genomic technology to increase genetic gain, Stephen Lee, School of Animal and Veterinary Sciences, University of Adelaide and Sheep Cooperative Research Centre (CRC) & Ian Robertson, Merinotech WA
11. Economics of feed lotting - to feed-lot or not?, Lucy Anderton, Economist, Department of Agriculture and Food, Western Australia
12. Anameka and other shrubs to fill feed gaps, Hayley Norman CSIRO & Ed Barrett-Lennard UWA & Department of Agriculture and Food, Western Australia
13. Sheep industry traineeships - encouraging a new generation of farmers, Jackie Jarvis, Consultant, Agrifood Labour & Skills
14. Opportunities and challenges facing youth in the sheep and wool industry, Ben Patrick, Yarrawonga Stu
Sheep Updates 2015 - Ravensthorpe
This session covers fourteen papers from different authors:
1. The Sheep Industry Business Innovation project, Bruce Mullan, Sheep Industry Development Director, Department of Agriculture and Food, Western Australia
2. Western Australian sheep stocktake, Kate Pritchett and Kimbal Curtis, Research Officers, Department of Agriculture and Food, Western Australia
3. Wool demand and supply - short term volatility, long term opportunities, Chris Wilcox, Principal of Poimena Analysis
4. Lifetime management for maternal ewes, Mike Hyder, Research Officer, Department of Agriculture and Food, Western Australia
5. National Livestock Identification System (NLIS) for sheep and goats - what is the NLIS database? Leigh Sonnermann, Biosecurity Officer, Department of Agriculture and Food, Western Australia
6. Myths, Facts and the role of animal welfare in farming, Lynne Bradshaw, president, RSPCA WA
7. Latest research and development on breech strike prevention, Geoff Lindon, Manager Productivity and Animal Welfare, AWI
8. Lamb Survival Initiative and 100% Club, Katherine Davies, Development Officer, Department of Agriculture and Food, Western Australia
9. How to boost your lamb survival, Joe Young, Sheep Consultant, R.B. Young and Son
10. Using genomic technology to increase genetic gain, Stephen Lee, School of Animal and Veterinary Sciences, University of Adelaide and Sheep Cooperative Research Centre (CRC) & Ian Robertson, Merinotech WA
11. Economics of feed lotting - to feed-lot or not?, Lucy Anderton, Economist, Department of Agriculture and Food, Western Australia
12. Anameka and other shrubs to fill feed gaps, Hayley Norman CSIRO & Ed Barrett-Lennard UWA & Department of Agriculture and Food, Western Australia
13. Sheep industry traineeships - encouraging a new generation of farmers, Jackie Jarvis, Consultant, Agrifood Labour & Skills
14. Opportunities and challenges facing youth in the sheep and wool industry, Ben Patrick, Yarrawonga Stu
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Variability in the global energy budget and transports 1985–2017
The study of energy flows in the Earth system is essential for understanding current climate change. To understand how energy is accumulating and being distributed within the climate system, an updated reconstruction of energy fluxes at the top of atmosphere, surface and within the atmosphere derived from observations is presented. New satellite and ocean data are combined with an improved methodology to quantify recent variability in meridional and ocean to land heat transports since 1985. A global top of atmosphere net imbalance is found to increase from 0.10 ± 0.61 W m−2 over 1985–1999 to 0.62 ± 0.1 W m−2 over 2000–2016, and the uncertainty of ± 0.61 W m−2 is related to the Argo ocean heat content changes (± 0.1 W m−2) and an additional uncertainty applying prior to 2000 relating to homogeneity adjustments. The net top of atmosphere radiative flux imbalance is dominated by the southern hemisphere (0.36 ± 0.04 PW, about 1.41 ± 0.16 W m−2) with an even larger surface net flux into the southern hemisphere ocean (0.79 ± 0.16 PW, about 3.1 ± 0.6 W m−2) over 2006–2013. In the northern hemisphere the surface net flux is of opposite sign and directed from the ocean toward the atmosphere (0.44 ± 0.16 PW, about 1.7 ± 0.6 W m−2). The sea ice melting and freezing are accounted for in the estimation of surface heat flux into the ocean. The northward oceanic heat transports are inferred from the derived surface fluxes and estimates of ocean heat accumulation. The derived cross-equatorial oceanic heat transport of 0.50 PW is higher than most previous studies, and the derived mean meridional transport of 1.23 PW at 26° N is very close to 1.22 PW from RAPID observation. The surface flux contribution dominates the magnitude of the oceanic transport, but the integrated ocean heat storage controls the interannual variability. Poleward heat transport by the atmosphere at 30° N is found to increase after 2000 (0.17 PW decade−1). The multiannual mean (2006–2013) transport of energy by the atmosphere from ocean to land is estimated as 2.65 PW, and is closely related to the ENSO variability
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The low-resolution version of HadGEM3 GC3.1: development and evaluation for global climate
A new climate model, HadGEM3 N96ORCA1, is presented that is part of the GC3.1 configuration of HadGEM3. N96ORCA1 has a horizontal resolution of ~135 km in the atmosphere and 1° in the ocean and requires an order of magnitude less computing power than its medium-resolution counterpart, N216ORCA025, while retaining a high degree of performance traceability. Scientific performance is compared both to observations and the N216ORCA025 model. N96ORCA1 reproduces observed climate mean and variability almost as well as N216ORCA025. Patterns of biases are similar across the two models. In the north-west Atlantic, N96ORCA1 shows a cold surface bias of up to 6K, typical of ocean models of this resolution. The strength of the Atlantic meridional overturning circulation (16 to 17 Sv) matches observations. In the Southern Ocean, a warm surface bias (up to 2K) is smaller than in N216ORCA025 and linked to improved ocean circulation. Model El Niño/Southern Oscillation and Atlantic Multidecadal Variability are close to observations. Both the cold bias in the Northern hemisphere (N96ORCA1) and the warm bias in the Southern hemisphere (N216ORCA025) develop in the first few decades of the simulations. As in many comparable climate models, simulated interhemispheric gradients of top-of-atmosphere radiation are larger than observations suggest, with contributions from both hemispheres. HadGEM3 GC3.1 N96ORCA1 constitutes the physical core of the UK Earth System Model (UKESM1) and will be used extensively in the Coupled Model Intercomparison Project 6 (CMIP6), both as part of UKESM1 and as a stand-alone coupled climate model
Epidemiology of injuries presenting to the national hospital in Kampala, Uganda: implications for research and policy
BackgroundDespite the growing burden of injuries in LMICs, there are still limited primary epidemiologic data to guide health policy and health system development. Understanding the epidemiology of injury in developing countries can help identify risk factors for injury and target interventions for prevention and treatment to decrease disability and mortality.AimTo estimate the epidemiology of the injury seen in patients presenting to the government hospital in Kampala, the capital city of Uganda.MethodsA secondary analysis of a prospectively collected database collected by the Injury Control Centre-Uganda at the Mulago National Referral Hospital, Kampala, Uganda, 2004-2005.ResultsFrom 1 August 2004 to 12 August 2005, a total of 3,750 injury-related visits were recorded; a final sample of 3,481 records were analyzed. The majority of patients (62%) were treated in the casualty department and then discharged; 38% were admitted. Road traffic injuries (RTIs) were the most common causes of injury for all age groups in this sample, except for those under 5 years old, and accounted for 49% of total injuries. RTIs were also the most common cause of mortality in trauma patients. Within traffic injuries, more passengers (44%) and pedestrians (30%) were injured than drivers (27%). Other causes of trauma included blunt/penetrating injuries (25% of injuries) and falls (10%). Less than 5% of all patients arriving to the emergency department for injuries arrived by ambulance.ConclusionsRoad traffic injuries are by far the largest cause of both morbidity and mortality in Kampala. They are the most common cause of injury for all ages, except those younger than 5, and school-aged children comprise a large proportion of victims from these incidents. The integration of injury control programs with ongoing health initiatives is an urgent priority for health and development
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UK Global Ocean GO6 and GO7: a traceable hierarchy of model resolutions
Versions 6 and 7 of the UK Global Ocean configuration (known as GO6 and GO7) will form the ocean components of the Met Office GC3.1 coupled model and UKESM1 earth system model to be used in CMIP61 simulations. The label “GO6” refers to a traceable hierarchy of three model configurations at nominal 1, 1∕4 and 1∕12° resolutions. The GO6 configurations are described in detail with particular focus on aspects which have been updated since the previous version (GO5). Results of 30-year forced ocean-ice integrations with the 1∕4° model are presented, in which GO6 is coupled to the GSI8.1 sea ice configuration and forced with CORE22 fluxes. GO6-GSI8.1 shows an overall improved simulation compared to GO5-GSI5.0, especially in the Southern Ocean where there are more realistic summertime mixed layer depths, a reduced near-surface warm and saline biases, and an improved simulation of sea ice. The main drivers of the improvements in the Southern Ocean simulation are tuning of the vertical and isopycnal mixing parameters. Selected results from the full hierarchy of three resolutions are shown. Although the same forcing is applied, the three models show large-scale differences in the near-surface circulation and in the short-term adjustment of the overturning circulation. The GO7 configuration is identical to the GO6 1∕4° configuration except that the cavities under the ice shelves are opened. Opening the ice shelf cavities has a local impact on temperature and salinity biases on the Antarctic shelf with some improvement in the biases in the Weddell Sea
Re-emergence of North Atlantic subsurface ocean temperature anomalies in a seasonal forecast system
A high-resolution coupled ocean atmosphere model is used to study the effects of seasonal re-emergence of North Atlantic subsurface ocean temperature anomalies on northern hemisphere winter climate. A 50-member control ensemble is integrated from 1 September 2007 to 28 February 2008 and compared with a parallel ensemble with perturbed ocean initial conditions. The perturbation consists of a density-compensated subsurface Atlantic temperature anomaly corresponding to the observed subsurface temperature anomaly for September 2010. The experiment is repeated for two atmosphere horizontal resolutions (~ 60 km and ~ 25 km) in order to determine whether the sensitivity of the atmosphere to re-emerging temperature anomalies is dependent on resolution. A wide range of re-emergence behavior is found within the perturbed ensembles. While the observations seem to indicate that most of the re-emergence is occurring in November, most members of the ensemble show re-emergence occurring later in the winter. However, when re-emergence does occur it is preceded by an atmospheric pressure pattern that induces a strong flow of cold, dry air over the mid-latitude Atlantic, and enhances oceanic latent heat loss. In response to re-emergence (negative SST anomalies), there is reduced latent heat loss, less atmospheric convection, a reduction in eddy kinetic energy and positive low-level pressure anomalies downstream. Within the framework of a seasonal forecast system the results highlight the atmospheric conditions required for re-emergence to take place and the physical processes that may lead to a significant effect on the winter atmospheric circulation
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