Tropical climate variability: interactions across the Pacific, Indian, and Atlantic Oceans

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this recordComplex interactions manifest between modes of tropical climate variability across the Pacific, Indian, and Atlantic Oceans. For example, the El Niño–Southern Oscillation (ENSO) extends its influence on modes of variability in the tropical Indian and Atlantic Oceans, which in turn feed back onto ENSO. Interactions between pairs of modes can alter their strength, periodicity, seasonality, and ultimately their predictability, yet little is known about the role that a third mode plays. Here we examine the interactions and relative influences between pairs of climate modes using ensembles of 100-year partially coupled experiments in an otherwise fully coupled general circulation model. In these experiments, the air–sea interaction over each tropical ocean basin, as well as pairs of ocean basins, is suppressed in turn. We find that Indian Ocean variability has a net damping effect on ENSO and Atlantic Ocean variability, and conversely they each promote Indian Ocean variability. The connection between the Pacific and the Atlantic is most clearly revealed in the absence of Indian Ocean variability. Our model runs suggest a weak damping influence by Atlantic variability on ENSO, and an enhancing influence by ENSO on Atlantic variability.This study was supported by the Australian Research Council’s Centre of Excellence for Climate System Science. This research was undertaken with the assistance of resources from the National Computational Infrastructure (NCI), which is supported by the Australian Government

Generation of the Amundsen Sea Low by Antarctic Orography

The Amundsen Sea Low (ASL) is a distinctive feature of the Southern Hemisphere high latitude atmospheric circulation, regulating regional Antarctic climate, meridional heat transport, ocean circulation, and sea-ice in the Amundsen-Bellingshausen Seas. Most previous research on the ASL has focused on its variability with only a few studies attempting to understand why the climatological ASL exists. These studies have proposed different hypotheses to explain the presence of the ASL, however, a clear understanding of the mechanisms responsible for the generation of the ASL remains uncertain. Here we use an atmospheric general circulation model to show that the ASL is a consequence of the interaction between Antarctic topography and the westerly wind jet, with negligible influence from low-latitude teleconnections. A nonrotating fluid flow simulation further suggests that the ASL can be explained by flow separation resulting from the interaction of westerly winds with the topography of Antarctica

Response of Southern Hemisphere Western Boundary Current Regions to Future Zonally Symmetric and Asymmetric Atmospheric Changes

Subtropical western boundary currents (WBCs) are often associated with hotspots of global warming, with certain WBC extension regions warming 3–4 times faster than the global mean. In the Southern Hemisphere, strong warming over the WBC extensions has been observed over the last few decades, with enhanced warming projected into the future. This amplified warming has primarily been linked to poleward intensification of the mid-latitude westerly winds in the Southern Hemisphere. Changes in these winds are often thought of as being zonally symmetric; however, recent studies show that they contain strong zonal asymmetries in certain ocean basins. The importance of these zonal asymmetries for the Southern Ocean has not yet been investigated. In this study, we use an ocean-sea-ice model forced by prescribed atmospheric fields to quantify the contribution of projected zonally asymmetric atmospheric changes in generating future ocean warming and circulation changes in the subtropical WBC regions. We find that the zonally asymmetric component of atmospheric forcing, characterized by a pattern that is consistent across CMIP6 models, can explain more than 30% (>2°C) of the sea surface temperature (SST) warming found in the Tasman Sea and southern Australia region and a sizable fraction of warming in the Agulhas Current region. These changes in SST in both the Indian and Pacific basins are found to be primarily driven by increases in the advection of warm tropical water to the mid-latitudes due to changes in the large-scale subtropical ocean gyres, which in turn can largely be explained by changes in the mid-latitude surface wind stress patterns

Historical and Projected Changes in the Southern Hemisphere Surface Westerlies

The Southern Hemisphere (SH) surface westerlies fundamentally control regional patterns of air temperature, storm tracks, and precipitation while also regulating ocean circulation, heat transport and carbon uptake. Wind-forced ocean perturbation experiments commonly apply idealized poleward wind shifts ranging between 0.5 and 10 degrees of latitude and wind intensification factors of between 10% and 300%. In addition, changes in winds are often prescribed ad hoc as a zonally uniform anomaly that neglects important regional and seasonal differences. Here we quantify historical and projected SH westerly wind changes based on examination of CMIP5, CMIP6, and reanalysis data. We find a significant reduction in the location bias of the CMIP6 ensemble and an associated reduction in the projected poleward shift compared to CMIP5. Under a high emission scenario, we find a projected end of 21st Century ensemble mean wind increase of ∼10% and a poleward shift of ∼0.8° latitude, although there are important seasonal and regional variations

On the choice of ensemble mean for estimating the forced signal in the presence of internal variability

This is the final version of the article. Available from American Meteorological Society via the DOI in this record.In this paper we examine various options for the calculation of the forced signal in climate model simulations, and the impact these choices have on the estimates of internal variability. We find that an ensemble mean of runs from a single climate model [a single model ensemble mean (SMEM)] provides a good estimate of the true forced signal even for models with very few ensemble members. In cases where only a single member is available for a given model, however, the SMEM from other models is in general out-performed by the scaled ensemble mean from all available climate model simulations [the multimodel ensemble mean (MMEM)]. The scaled MMEM may therefore be used as an estimate of the forced signal for observations. The MMEM method, however, leads to increasing errors further into the future, as the different rates of warming in the models causes their trajectories to diverge. We therefore apply the SMEM method to those models with a sufficient number of ensemble members to estimate the change in the amplitude of internal variability under a future forcing scenario. In line with previous results, we find that on average the surface air temperature variability decreases at higher latitudes, particularly over the ocean along the sea ice margins, while variability in precipitation increases on average, particularly at high latitudes. Variability in sea level pressure decreases on average in the Southern Hemisphere, while in the Northern Hemisphere there are regional differences.This work was supported by the Australian Research Council (ARC) through grants to L. M. F. (DE170100367) and to M. H. E. through the ARC Centre of Excellence in Climate System Science (CE110001028). J. B. K. is supported by the Natural Environment Research Council (Grant NE/N005783/1). B. A. S. was supported by the U.S. National Science Foundation (EAR-1447048)

Zonal wave 3 pattern in the Southern Hemisphere generated by tropical convection

A distinctive feature of the Southern Hemisphere extratropical atmospheric circulation is the quasi-stationary zonal wave 3 pattern. This pattern is present in both the mean atmospheric circulation and its variability on daily, seasonal and interannual timescales. While the zonal wave 3 pattern has substantial impacts on meridional heat transport and Antarctic sea ice extent, the reason for its existence remains uncertain, although it has long been assumed to be linked to the presence of three major landmasses in the Southern Hemisphere extratropics. Here we use an atmospheric general circulation model to show that the stationary zonal wave 3 pattern is instead driven by zonally asymmetric deep convection in the tropics, with little influence from extratropical orography or landmasses. Localized regions of deep convection in the tropics form a local Hadley cell, which in turn creates a wave source in the subtropics that excites a poleward- and eastward-propagating wave train, forming quasi-stationary waves in the Southern Hemisphere high latitudes. Our findings suggest that changes in tropical deep convection, either due to natural variability or climate change, fundamentally control the zonal wave 3 pattern, with implications for southern high-latitude climate, ocean circulation and sea ice

Qualitative study exploring the phenomenon of multiple electronic prescribing systems within single hospital organisations

BACKGROUND: A previous census of electronic prescribing (EP) systems in England showed that more than half of hospitals with EP reported more than one EP system within the same hospital. Our objectives were to describe the rationale for having multiple EP systems within a single hospital, and to explore perceptions of stakeholders about the advantages and disadvantages of multiple systems including any impact on patient safety. METHODS: Hospitals were selected from previous census respondents. A decision matrix was developed to achieve a maximum variation sample, and snowball sampling used to recruit stakeholders of different professional backgrounds. We then used an a priori framework to guide and analyse semi-structured interviews. RESULTS: Ten participants, comprising pharmacists and doctors and a nurse, were interviewed from four hospitals. The findings suggest that use of multiple EP systems was not strategically planned. Three co-existing models of EP systems adoption in hospitals were identified: organisation-led, clinician-led and clinical network-led, which may have contributed to multiple systems use. Although there were some perceived benefits of multiple EP systems, particularly in niche specialities, many disadvantages were described. These included issues related to access, staff training, workflow, work duplication, and system interfacing. Fragmentation of documentation of the patient's journey was a major safety concern. DISCUSSION: The complexity of EP systems' adoption and deficiencies in IT strategic planning may have contributed to multiple EP systems use in the NHS. In the near to mid-term, multiple EP systems may remain in place in many English hospitals, which may create challenges to quality and patient safety.Peer reviewe

CMIP5 Intermodel Relationships in the Baseline Southern Ocean Climate System and With Future Projections

This is the final version. Available on open access from Wiley via the DOI in this recordClimate models exhibit a broad range in the simulated properties of the climate system. In the early historical period, the absolute global mean surface air temperature in Coupled Model Intercomparison Project, phase 5 (CMIP5) models spans a range of ~12-15 °C. Other climate variables may be linked to global mean temperature, and so accurate representation of the baseline climate state is crucial for meaningful future climate projections. In CMIP5 baseline climate states, statistically significant intermodel correlations between Southern Ocean surface temperature, outgoing shortwave radiation, cloudiness, the position of the mid-latitude eddy-driven jet, and Antarctic sea ice area are found. The baseline temperature relationships extend to projected future changes in the same set of variables. The tendency for models with initially cooler Southern Ocean to exhibit more global warming, and vice versa for initially warmer models, is linked to baseline Southern Ocean climate system biases. Some of these intermodel correlations arise due to a ‘capacity for change’. For example, models with more sea ice initially have greater capacity to lose sea ice as the planet warms, whereas models with little sea ice initially are constrained in the amount they can lose. Similar constraints apply to Southern Ocean clouds, which are projected to reduce under radiative forcing, and the jet latitude, which is projected to migrate poleward. A first look at emerging data from CMIP6 reveals a shift of the relationship from the Southern Ocean towards the Antarctic region, possibly due to reductions in Southern Ocean biases, such westerly wind representation.Natural Environment Research Council (NERC)Centre for Southern Hemisphere Oceans ResearchAustralian Government National Environmental Science ProgramAustralian Research Council (ARC

Work‐related post‐traumatic stress symptoms in obstetricians and gynaecologists: findings from INDIGO a mixed methods study with a cross‐sectional survey and in‐depth interviews

Objectives: To explore obstetricians’ and gynaecologists’ experiences of work‐related traumatic events, to measure the prevalence and predictors of post‐traumatic stress disorder (PTSD), any impacts on personal and professional lives, and any support needs. Design: Mixed methods: cross‐sectional survey and in‐depth interviews. Sample and setting: Fellows, members and trainees of the Royal College of Obstetricians and Gynaecologists (RCOG). Methods: A survey was sent to 6300 fellows, members and trainees of RCOG. 1095 people responded. Then 43 in‐depth interviews with trauma‐exposed participants were completed and analysed by template analysis. Main outcome measures: Exposure to traumatic work‐related events and PTSD, personal and professional impacts, and whether there was any need for support. Interviews explored the impact of trauma, what helped or hindered psychological recovery, and any assistance wanted. Results: Two‐thirds reported exposure to traumatic work‐related events. Of these, 18% of both consultants and trainees reported clinically significant PTSD symptoms. Staff of black or minority ethnicity were at increased risk of PTSD. Clinically significant PTSD symptoms were associated with lower job satisfaction, emotional exhaustion and depersonalisation. Organisational impacts included sick leave, and ‘seriously considering leaving the profession’. 91% wanted a system of care. The culture in obstetrics and gynaecology was identified as a barrier to trauma support. A strategy to manage the impact of work‐place trauma is proposed. Conclusions: Exposure to work‐related trauma is a feature of the experience of obstetricians and gynaecologists. Some will suffer PTSD with high personal, professional and organisational impacts. A system of care is needed