CLIWOC multilingual meteorological dictionary

This dictionary is the first attempt to express the wealth of archaic logbook wind force terms in a form that is comprehensible to the modern-day reader. Oliver and Kington (1970) and Lamb (1982) have drawn attention to the importance of logbooks in climatic studies, and Lamb (1991) offered a conversion scale for early eighteenth century English wind force terms, but no studies have thus far pursued the matter to any greater depth. This text attempts to make good this deficiency, and is derived from the research undertaken by the CLIWOC project1 in which British, Dutch, French and Spanish naval and merchant logbooks from the period 1750 to 1850 were used to derive a global database of climatic information. At an early stage in the project it was apparent that many of the logbook weather terms, whilst conforming to a conventional vocabulary, possessed meanings that were unclear to twenty-first century readers or had changed over time. This was particularly the case for the important element of wind force; but no special plea is entered for the evolution in nautical vocabulary, which often reflected more wide-ranging changes in the respective native languages.The key objective was to translate the archaic vocabulary of the late eighteenth and early nineteenth century mariner into expressions directly comparable with the Beaufort Scale (see Appendix I). Only then could the projects scientific programme be embarked upon. This dictionary is the result of the largest undertaking into logbook studies that has yet been carried out. Several thousand logbooks from British, Dutch, French and Spanish archives were examined, and the exercise offered a unique opportunity to explore the vocabulary of the one hundred year period beginning in 1750. The logbooks from which the raw data have been abstracted range widely across the North and South Atlantic and the Indian Oceans. Only the Pacific, largely in consequence of the paucity of regular naval activity in that area, is not well represented. The range of climates encountered in this otherwise wide geographic domain gives ample opportunity for the full range of the mariners nautical weather vocabulary to be assessed, from the calms of the Equatorial regions, through the gales of the mid-latitude systems to the fearsome storms of the tropical latitudes. The Trade Winds belts, the Doldrums, the unsettled mid-latitudes, even the icy wastes of the high latitudes, are all embraced in this study. It is not here intended to pass any judgements on the climatological record of the logbooks, and this text seeks only to provide a means of understanding archaic wind force terms and, other than to indicate those items that were not commonly used, no information is given on the frequency with which different terms appeared in the logbooks. Attention is, furthermore, confined to Dutch, English, French and Spanish because these once great imperial powers were the only nations able to support wide-ranging ocean-going fleets with their attendant collections of logbooks and documents over this long period of time. The work is offered to the wider academic community in the hope that they will prove to be of as much value as it has been to the CLIWOC team

Reconstructing El Niño Southern Oscillation using data from ships' logbooks, 1815- 1854. Part I: Methodology and Evaluation

The meteorological information found within ships’ logbooks is a unique and fascinating source of data for historical climatology. This study uses wind observations from logbooks covering the period 1815 to 1854 to reconstruct an index of El Niño Southern Oscillation (ENSO) for boreal winter (DJF). Statistically-based reconstructions of the Southern Oscillation Index (SOI) are obtained using two methods: principal component regression (PCR) and composite-plus-scale (CPS). Calibration and validation are carried out over the modern period 1979–2014, assessing the relationship between re-gridded seasonal ERA-Interim reanalysis wind data and the instrumental SOI. The reconstruction skill of both the PCR and CPS methods is found to be high with reduction of error skill scores of 0.80 and 0.75, respectively. The relationships derived during the fitting period are then applied to the logbook wind data to reconstruct the historical SOI. We develop a new method to assess the sensitivity of the reconstructions to using a limited number of observations per season and find that the CPS method performs better than PCR with a limited number of observations. A difference in the distribution of wind force terms used by British and Dutch ships is found, and its impact on the reconstruction assessed. The logbook reconstructions agree well with a previous SOI reconstructed from Jakarta rain day counts, 1830–1850, adding robustness to our reconstructions. Comparisons to additional documentary and proxy data sources are provided in a companion paper

Application of nearest-neighbor resampling for homogenizing temperature records on a daily to subdaily level.

ABSTRACT Nearest-neighbor resampling is introduced as a means for homogenizing temperature records on a daily to sub-daily level. Homogenization refers here to the problem of calculating daily mean and sub-daily temperatures from a time series subject to irregular observation frequencies and changing observation schedules. The method resamples diurnal temperature cycles from an observed hourly temperature subrecord at the station. Unlike other methods, the technique maintains the variance in a natural way. This property is especially important for the analysis of trends and variability of extremes. For a given day, the resampling technique does not generate a single-valued solution but this peculiarity is of no effect in the applications considered here. The skills of the nearest-neighbor resampling technique, in terms of bias, RMSE, and variability, are compared with those of four other methods: a sine-exponential model, a model that uses the climatological mean daily cycle, a regression model for calculating daily values, and a deterministic version of the nearestneighbor technique. The series used in the tests is the 1951-2000 meteorological record of De Bilt (The Netherlands). The emphasis in the comparisons is on the reconstruction of daily mean temperatures. The analysis shows important differences in performance between the models. The regression-based method performs best with respect to the calculation of the individual daily mean temperatures; the day-to-day variability is best reproduced with the nearest-neighbor resampling technique. The performance of the models improves when cloudiness is used as an extra predictor. The improvement is, however, small compared to the intermodel differences. The type of model that should be used depends on the desired application. For trend and variability studies, the nearest-neighbor resampling technique performs best. Nearest-neighbor resampling can successfully be performed even in situations where the length of the hourly subrecord is an order of magnitude less than the length of the series to be homogenized

Thematische collectie: CLIWOC: Scheepsjournaals en databases, 1750-1850

Hoofddoel van het CLIWOC-project was het benutten van klimaatgegevens uit scheepsjournaals voor het aanleggen van een database van dagelijkse weer-observaties voor oceanen uit de periode 1750 - 1850. Een van de belangrijkste resultaten van het project is een database met gegevens uit Britse, Nederlandse, Franse en Spaanse scheepsjournaals uit de pre-industriële periode (1750 - 1853). In deze thematische collectie wordt een deel van de Nederlandse inbreng samengebracht. Tijdens de oorspronkelijke gegevensverzameling in de periode december 2000 tot en met november 2003 werden per scheepsreis gegevens verzameld in MS Access databases. De datasets in deze collectie bevatten deze oorspronkelijke databases samen met de afbeeldingen van de bijbehorende scheepsjournaals