Awe, Samuel O. and Mahony, Martin and Michaud, Edley and Murphy, Conor and Noone, Simon J. and Venema, Victor K. C. and Thorne, Thomas G. and Thorne, Peter (2022) Insights from 20 years of temperature parallel measurements in Mauritius around the turn of the 20th century. Climate of the Past, 18 (4). pp. 793-820. ISSN 1814-9332

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Abstract

There is considerable import in creating more complete, better understood holdings of early meteorolog- ical data. Such data permit an improved understanding of climate variability and long-term changes. Early records are particularly incomplete in the tropics, with implications for estimates of global and regional temperature. There is also a relatively low level of scientific understanding of how these early measurements were made and, as a result, of their ho- mogeneity and comparability to more modern techniques and measurements. Herein we describe and analyse a newly rescued set of long-term, up to six-way parallel measure- ments undertaken over 1884–1903 in Mauritius, an island situated in the southern Indian Ocean. Data include (i) mea- surements from a well-ventilated room, (ii) a shaded thermo- graph, (iii) instruments housed in a manner broadly equiv- alent to a modern Stevenson screen, (iv) a set of measure- ments by a hygrometer mounted in a Stevenson screen, and for a much shorter period (v) two additional Stevenson screen configurations. All measurements were undertaken within an ∼ 80 m radius of each other. To our knowledge this is the first such multidecadal multi-instrument assessment of meteoro- logical instrument transition impacts ever undertaken, pro- viding potentially unique insights. The intercomparison also considers the impact of different ways of deriving daily and monthly averages. The long-term comparison is sufficient to robustly characterize systematic offsets between all the in- struments and seasonally varying impacts. Differences be- tween all techniques range from tenths of a degree Celsius to more than 1 ◦C and are considerably larger for maximum and minimum temperatures than for means or averages. System- atic differences of several tenths of a degree Celsius also exist for the different ways of deriving average and mean tempera- tures. All differences, except two average temperature series pairs, are significant at the 0.01 level using a paired t test. Given that all thermometers were regularly calibrated against a primary Kew standard thermometer maintained by the ob- servatory, this analysis highlights significant impacts of in- strument exposure, housing, siting, and measurement prac- tices in early meteorological records. These results reaffirm the importance of thoroughly assessing the homogeneity of early meteorological records.

Item Type:	Article
Keywords:	Insights; 20 years; temperature parallel measurements; Mauritius; 20th century;
Academic Unit:	Faculty of Social Sciences > Geography Faculty of Social Sciences > Research Institutes > Irish Climate Analysis and Research Units, ICARUS
Item ID:	16948
Identification Number:	https://doi.org/10.5194/cp-18-793-2022
Depositing User:	Peter Thorne
Date Deposited:	20 Feb 2023 12:42
Journal or Publication Title:	Climate of the Past
Publisher:	European Geosciences Union (EGU)
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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