Sensitivity of stratospheric water vapour to variability in tropical tropopause temperatures and large-scale transport

Abstract. Concentrations of water vapour entering the tropical lower stratosphere are primarily determined by conditions that air parcels encounter as they are transported through the tropical tropopause layer (TTL). Here we quantify the relative roles of variations in TTL temperatures and transport in determining seasonal and interannual variations of stratospheric water vapour. Following previous studies, we use trajectory calculations with the water vapour concentration set by the Lagrangian dry point (LDP) along trajectories. To assess the separate roles of transport and temperatures, the LDP calculations are modified by replacing either the winds or the temperatures with those from different years to investigate the wind or temperature sensitivity of water vapour to interannual variations and, correspondingly, with those from different months to investigate the wind or temperature sensitivity to seasonal variations. Both ERA-Interim reanalysis data for the 1999–2009 period and data generated by a chemistry–climate model (UM-UKCA) are investigated. Variations in temperatures, rather than transport, dominate interannual variability, typically explaining more than 70 % of variability, including individual events such as the 2000 stratospheric water vapour drop. Similarly seasonal variation of temperatures, rather than transport, is shown to be the dominant driver of the annual cycle in lower stratospheric water vapour concentrations in both the model and reanalysis, but it is also shown that seasonal variation of transport plays an important role in reducing the seasonal cycle maximum (reducing the annual range by about 30 %). The quantitative role in dehydration of sub-seasonal and sub-monthly Eulerian temperature variability is also examined by using time-filtered temperature fields in the trajectory calculations. Sub-monthly temperature variability reduces annual mean water vapour concentrations by 40 % in the reanalysis calculation and 30 % in the model calculation. As with other aspects of dehydration, simple Eulerian measures of variability are not sufficient to quantify the implications for dehydration, and the Lagrangian sampling of the variability must be taken into account. These results indicate that, whilst capturing seasonal and interannual variation of temperature is a major factor in modelling realistic stratospheric water vapour concentrations, simulation of seasonal variation of transport and of sub-seasonal and sub-monthly temperature variability are also important and cannot be ignored. </jats:p

New WHO Violence Prevention Information System, an interactive knowledge platform of scientific findings on violence.

Scientific information on violence can be difficult to compile and understand. It is scattered across websites, databases, technical reports and academic journals, and rarely addresses all types of violence. In response, in October 2017 WHO released the Violence Prevention Information System or Violence Info, an online interactive collection of scientific information about the prevalence, consequences, risk factors and preventability of all forms of interpersonal violence. It covers homicide, child maltreatment, youth violence, intimate partner violence, elder abuse and sexual violence

Improvements to the Red List Index

The Red List Index uses information from the IUCN Red List to track trends in the projected overall extinction risk of sets of species. It has been widely recognised as an important component of the suite of indicators needed to measure progress towards the international target of significantly reducing the rate of biodiversity loss by 2010. However, further application of the RLI (to non-avian taxa in particular) has revealed some shortcomings in the original formula and approach: It performs inappropriately when a value of zero is reached; RLI values are affected by the frequency of assessments; and newly evaluated species may introduce bias. Here we propose a revision to the formula, and recommend how it should be applied in order to overcome these shortcomings. Two additional advantages of the revisions are that assessment errors are not propagated through time, and the overall level extinction risk can be determined as well as trends in this over time

Employment mobility in high-technology agglomerations: the cases of Oxfordshire and Cambridgeshire

This paper examines labour market behaviour of the highly skilled in high-tech local economies, taking the UK examples of Oxfordshire and Cambridgeshire as case studies. It reports on data from a survey of members of three scientific institutes to compare rates of employee mobility in the two locations and considers the likely explanations and implications of those patterns

Possible impacts of a future grand solar minimum on climate: Stratospheric and global circulation changes.

This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/2014JD022022A future decline in solar activity would not offset projected global warmingA future decline in solar activity could have larger regional effects in winterTop-down mechanism contributes to Northern Hemisphere regional response.LJG and ACM were supported by the National Centre for Atmospheric Science's Climate Directorate. ACM also acknowledges support from the ERC ACCI project no. 267760 and an AXA Postdoctoral Fellowship. SI and AAS were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). LJG and JAA were supported by a grant from the National Environmental Research Council

A chemistry-transport model simulation of middle atmospheric ozone from 1980 to 2019 using coupled chemistry GCM winds and temperatures

International audienceA Global 40-year simulation from 1980 to 2019 was performed with the FinROSE chemistry-transport model based on the use of coupled chemistry GCM-data. The main focus of our analysis is on climatological-scale processes in high latitudes. The resulting trend estimates for the past period (1980?1999) agree well with observation-based trend estimates. The results for the future period (2000?2019) suggest that the extent of seasonal ozone depletion over both northern and southern high-latitudes has likely reached its maximum. Furthermore, while climate change is expected to cool the stratosphere, this cooling is unlikely to accelerate significantly high latitude ozone depletion. However, the recovery of seasonal high latitude ozone losses will not take place during the next 15 years