Dennis A Wheeler

Chapter 1 Mediterranean climate variability over the last centuries: A review

Publisher Summary This chapter discusses a necessary task for assessing to which degree the industrial period is unusual against the background of pre-industrial climate variability. It is the reconstruction and interpretation of temporal and spatial patterns of climate in earlier centuries. There are distinct differences in the temporal resolution among the various proxies. Some of the proxy records are annually or even higher resolved and hence record year-by-year patterns of climate in past centuries. Several of the temperature reconstructions reveal that the late twentieth century warmth is unprecedented at hemispheric scales and is explained by anthropogenic, greenhouse gas (GHG) forcing. The chapter discusses the availability and potential of long, homogenized instrumental data, documentary, and natural proxies to reconstruct aspects of past climate at local- to regional-scales within the larger Mediterranean area, which includes climate extremes and the incidence of natural disasters. The chapter describes the role of external forcing, including natural and anthropogenic influences, and natural, internal variability in the coupled ocean–atmosphere system at subcontinental scale.

MARINE OBSERVATIONS OF OLD WEATHER

Weather observations are vital for climate change monitoring and prediction. For the worlds oceans, there are many meteorological and oceanographic observations available back to the mid-twentieth century, but coverage is limited in earlier periods, and particularly also during the two world wars. Before 1850 there are currently very few instrumental observations available. Consequently, detailed observational estimates of surface climate change can be made only back to the mid-nineteenth century. To improve and extend this early coverage, scientists need more observations from these periods. Fortunately, many such observations exist in logbooks, reports, and other paper records, but their inclusion in the climatic datasets requires that these paper records be abstracted from the worlds archives, digitized into an electronic form, and blended into existing climate databases. As a first step in this direction, selected Royal Navy logbooks from the period of 1938–47, kept in the U.K. National Archives, ha...

ANALYSIS OF THE BARCELONA PRECIPITATION SERIES 1850-1991

Interest in climatic change has never been greater and it is inevitable that the search for periodicities in the climatic record should be a popular means of attempting to unravel at least some of the complexities of the atmospheric system. This paper reviews aspects of the methodologies of spectral analysis and takes the example of the Barcelona precipitation series (1850‐1991) to illustrate how both spectral analysis and other statistical analyses can provide information on climatic evolution as expressed through the medium of this one variable. Copyright

A HISTORICAL ANALOG OF 2005 HURRICANE VINCE

This paper documents a rare spell of severe weather in Spain that took place during the mid-nineteenth century when a tropical storm struck the southwest of the country on 29 October 1842. The use of a variety of independent documentary sources has provided unprecedented scope for the analysis of this event, allowing it to be set within its wider context, and for a judgement to be made on its tropical origin. The evidence suggests that this was similar, though stronger, to the more recent Hurricane Vince, which made landfall in Spain on 10 October 2005. This case study not only places Hurricane Vince, suggested at the time to have been unique, in its more proper long-term context, but it also demonstrates how documentary sources can improve our wider understanding of climate dynamics during historical times in the Atlantic basin.

Witnessing North Atlantic westerlies variability from ships’ logbooks (1685–2008)

Abstract A monthly index based on the persistence of the westerly winds over the English Chanel is constructed for 1685–2008 using daily data from ships’ logbooks and comprehensive marine meteorological datasets. The so-called Westerly Index (WI) provides the longest instrumental record of atmospheric circulation currently available. Anomalous WI values are associated with spatially coherent climatic signals in temperature and precipitation over large areas of Europe, which are stronger for precipitation than for temperature and in winter and summer than in transitional seasons. Overall, the WI series accord with the known European climatic history, and reveal that the frequency of the westerlies in the eastern Atlantic during the twentieth century and the Late Maunder Minimum was not exceptional in the context of the last three centuries. It is shown that the WI provides additional and complementary information to the North Atlantic Oscillation (NAO) indices. The analysis of WI series during the industrial era indicates an overall good agreement with the winter and high-summer NAO, with the exception of several multidecadal periods of weakened correlation. These decoupled periods between the frequency and the intensity of the zonal flow are interpreted on the basis of several sources of non-stationarity affecting the centres of the variability of the North Atlantic and their teleconnections. Comparisons with NAO reconstructions and long instrumental indices extending back to the seventeenth century suggest that similar situations have occurred in the past, which call for caution when reconstructing the past atmospheric circulation from climatic proxies. The robustness and extension of its climatic signal, the length of the series and its instrumental nature make the WI an excellent benchmark for proxy calibration in Europe and Greenland.

A Pioneer in Tropical Meteorology: William Sharpe's Barbados Weather Journal, April–August 1680

The first barometers in the Americas were provided by the Royal Society of London in 1677 to correspondents in the Caribbean Island of Barbados. Colonel William Sharpe of Barbados was the first person in the Americas to make daily observations of the weather using a meteorological instrument (other than a wind vane) and made the first known measurements of barometric pressure within the circulation of a hurricane on 12 August 1680. His record provides new insight into the early history of the barometer and early perceptions of tropical weather, vindicates the hypothesis that the barometer would prove useful in detecting hurricanes, and contributes to Edmund Halleys understanding of the empirical distinctions between the Tropics and temperate zones. Sharpes name and contributions, previously unknown to the meteorological community, can now be properly recognized.

A verification of UK gale forecasts by the ‘solar weather technique’: October 1995–September 1997

Abstract In recent years the ‘solar weather’ technique of weather forecasting which takes into account of the influence of the sun has received much attention. No attempt has hitherto been made to determine the success, or otherwise, of elements of these forecasts, which include solar predictors and are prepared 6–11 months in advance of the events they predict. This paper conducts an evaluation of these forecasts but confines attention to the prediction of gales. Skill levels are assessed over different seasons. The results, whilst differing greatly between the seasons, reveal a degree of success that cannot readily be accounted for by chance and suggest that this system of forecasting continues to be assessed over a longer time period to further investigate these findings.

Hudson's Bay Company ship's logbooks: a source of far North Atlantic weather data

The Arctic region is widely recognised to be one of the most sensitive to climate change. Here, the consequences of current trends will be felt most keenly; ice cap melting and thinning and the consequent implications for sea level rise and loss of habitat may be profound. Yet these regions remain amongst the most poorly chronicled. Recent advances in satellite monitoring and instrumental observations now provide valuable information, but this record extends over little more than half a century. For earlier times, the record is, at best, patchy and inconsistent. This is not, however, to imply that all such data and information have been recognised and fully exploited. This is far from the case and this paper draws attention to largely overlooked documentary sources that can extend our knowledge of the far North Atlantic climate back to the late eighteenth century. These documents consist of the logbooks of sailing ships navigating those hazardous waters in the late eighteenth and early- to mid-nineteenth centuries. This paper focuses specifically on those logbooks kept on board Hudsons Bay Company (HBC) ships on their regular annual voyages between the UK and Hudsons Bay between 1760 and 1870. The information they contain is shown to be detailed, reliable and of unique character for the period and place. The style and form of presentation of the logbooks is reviewed and particularly those aspects that deal with the daily meteorological information they contain. Attention is also drawn to the high degree of homogeneity found in the logbooks in terms of presentation and methods of preparation, rendering them directly and helpfully comparable one with another. A specific example is offered of the benefits of using these data and it is proposed that this set of logbooks, when taken collectively and, embracing as it does over a century from 1750 provides a matchless, substantial and uniformly reliable source of oceanic weather information for the far North Atlantic for what can be regarded as the ‘pre-instrumental’ period (before 1850).

The weather diary of Margaret Mackenzie of Delvine (Perthshire): 1780–1805

Abstract The weather diary kept by Margaret MacKenzie at Delvine (Perthshire) between 1780 and 1805 was recently discovered in the archives of the Royal Society of Edinburgh. It contains a daily temperature record with other useful observations on the state of the weather. The dates, location and rural setting in which the observations were made lends particular significance to their interpretation for purposes of climatic reconstruction

Ship logbooks help analyze pre-instrumental climate

The Climatological Database for the Worlds Oceans: 1750–1854 (CLIWOC) project, which concluded in 2004, abstracted more than 280,000 daily weather observations from ships logbooks from British, Dutch, French, and Spanish naval vessels engaged in imperial business in the eighteenth and nineteenth centuries. These data, now compiled into a database, provide valuable information for the reconstruction of oceanic wind field patterns for this key period that precedes the time in which anthropogenic influences on climate became evident. These reconstructions, in turn, provide evidence for such phenomena as the El Nino-Southern Oscillation and the North Atlantic Oscillation. Of equal importance is the finding that the CLIWOC database—the first coordinated attempt to harness the scientific potential of this resource [Garcia-Herrera et al., 2005]—represents less than 10 percent of the volume of data currently known to reside in this important but hitherto neglected source.