Climatology of Upper Tropospheric–Lower Stratospheric (UTLS) Jets and Tropopauses in MERRA

A global climatology (1979–2012) from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) shows distributions and seasonal evolution of upper tropospheric jets and their relationships to the stratospheric subvortex and multiple tropopauses. The overall climatological patterns of upper tropospheric jets confirm those seen in previous studies, indicating accurate representation of jet stream dynamics in MERRA. The analysis shows a Northern Hemisphere (NH) upper tropospheric jet stretching nearly zonally from the mid-Atlantic across Africa and Asia. In winter–spring, this jet splits over the eastern Pacific, merges again over eastern North America, and then shifts poleward over the North Atlantic. The jets associated with tropical circulations are also captured, with upper tropospheric westerlies demarking cyclonic flow downstream from the Australian and Asian monsoon anticyclones and associated easterly jets. Multiple tropopauses associated with the thermal tropopause “break” commonly extend poleward from the subtropical upper tropospheric jet. In Southern Hemisphere (SH) summer, the tropopause break, along with a poleward-stretching secondary tropopause, often occurs across the tropical westerly jet downstream of the Australian monsoon region. SH high-latitude multiple tropopauses, nearly ubiquitous in June–July, are associated with the unique polar winter thermal structure. High-latitude multiple tropopauses in NH fall–winter are, however, sometimes associated with poleward-shifted upper tropospheric jets. The SH subvortex jet extends down near the level of the subtropical jet core in winter and spring. Most SH subvortex jets merge with an upper tropospheric jet between May and December; although much less persistent than in the SH, merged NH subvortex jets are common between November and April.

Poetry on Pre-Raphaelite principles: science, nature and knowledge in William Michael Rossetti’s 'Fancies at Leisure' and 'Mrs. Holmes Grey'

This article demonstrates how early Pre-Raphaelite poetry worked according to the principle that art should be modelled on science theorised by the Pre-Raphaelites in their early essays. As the main theorists (rather than practitioners) of Pre-Raphaelite art, F. G. Stephens and William Michael Rossetti defined the Pre-Raphaelite project in terms of observation, investigation, experiment, the “adherence to fact” and the “search after truth”. In the hands of the early Pre-Raphaelite poets, and particularly Rossetti himself, poetry too becomes a mode of scientific enquiry into the natural world, the nature of observation, human psychology and medical practice.

Challenges in quantifying changes in the global water cycle

Understanding observed changes to the global water cycle is key to predicting future climate changes and their impacts. While many datasets document crucial variables such as precipitation, ocean salinity, runoff, and humidity, most are uncertain for determining long-term changes. In situ networks provide long time-series over land but are sparse in many regions, particularly the tropics. Satellite and reanalysis datasets provide global coverage, but their long-term stability is lacking. However, comparisons of changes among related variables can give insights into the robustness of observed changes. For example, ocean salinity, interpreted with an understanding of ocean processes, can help cross-validate precipitation. Observational evidence for human influences on the water cycle is emerging, but uncertainties resulting from internal variability and observational errors are too large to determine whether the observed and simulated changes are consistent. Improvements to the in situ and satellite observing networks that monitor the changing water cycle are required, yet continued data coverage is threatened by funding reductions. Uncertainty both in the role of anthropogenic aerosols, and due to large climate variability presently limits confidence in attribution of observed changes.

Persia and kingship in William Cartwright's The Royall Slave (1636)

The recent reorientation of early modern studies draws attention to the Renaissance stage as a site of exploration of images of the Islamic world. This article examines the use of ancient and contemporary Persia in William Cartwright’s The Royall Slave (1636), in which Persia figures as a convenient space through which to examine political issues relevant to the audience at home in England. Assessing the construction of idealized societies and rulers in the play, The Royall Slave is a contemporary Court and academic drama that demonstrates its importance as one of a number of synchronous texts that represent Persia.

Economic crises in England, 1270-1520: a statistical approach

The chapter examines how far medieval economic crises can be identified by analysing the residuals from a simultaneous equation model of the medieval English economy. High inflation, falls in gross domestic product and large intermittent changes in wage rates are all considered as potential indicators of crisis. Potential causal factors include bad harvests, wars and political instability. The chapter suggests that crises arose when a combination of different problems overwhelmed the capacity of government to address them. It may therefore be a mistake to look for a single cause of any crisis. The coincidence of separate problems is a more plausible explanation of many crises.

Modelling the medieval economy: money, prices and income in England, 1263-1520

This chapter presents a simple econometric model of the medieval English economy, focusing on the relationship between money, prices and incomes. The model is estimated using annual data for the period 1263-1520 obtained from various sources. The start date is determined by the availability of continuous runs of annual data, while the finishing date immediately precedes the take-off of Tudor price inflation. Accounts from the ecclesiastical and monastic estates have survived in great numbers for this period, thereby ensuring that crop yields can be estimated from a regionally representative set of estates.