The global historical climate database HCLIM

Abstract

There is a growing need for past weather and climate data to support science and decision-making. This paper describes the compilation and construction of a global multivariable (air temperature, pressure, precipitation sum, number of precipitation days) monthly instrumental climate database that encompasses a substantial body of the known early instrumental time series. The dataset contains series compiled from existing databases that start before 1890 (though continuing to the present) as well as a large amount of newly rescued data. All series underwent a quality control procedure and subdaily series were processed to monthly mean values. An inventory was compiled, and the collection was deduplicated based on coordinates and mutual correlations. The data are provided in a common format accompanied by the inventory. The collection totals 12452 meteorological records in 118 countries. The data can be used for climate reconstructions and analyses. It is the most comprehensive global monthly climate dataset for the preindustrial period so far.

Fig. 1

Schematic diagram, showing the sequence of steps involved in the data collection.

Fig. 2

(a) Spatial distribution of the newly digitized records organized by source and (b) Start year of the rescued records. (c) Time evolution of the number of digitized records. (d) Histogram of the length of the records that have been digitized.

Fig. 3

Records that were checked for duplication, deduplicated and merged from Madison.

Fig. 4

(a) The merged temperature record from Madison with homogeneity breaks after the breakpoint detection. The thick line shows the rolling mean or moving average, here based on every decade. (b) Meteorological stations named Madison in four states in the USA (Wisconsin, Nebraska, Indiana, and Florida).

Fig. 5

Example of a SEF file: Temperature record from Berlin 1719, from the Dove Collection.

Fig. 6

Temperature, pressure, precipitation, and wet day records in HCLIM by start year.

Fig. 7

Length of the time series in years before 1891.

Fig. 8

(a) Time evolution of the number of records per parameter (note the logarithmic scale). (b) Histogram of the length of all the records until 2021.

Fig. 9

(a) The oldest and longest temperature time series in the world from Paris that shows mean annual temperature for the years 1658–2018. The black dashed lines indicate homogeneity breaks (HCLIM). (b) The oldest and longest air pressure time series in the world from Paris, showing mean annual air pressure in hPa for the years 1670–2007 (the time series has a gap between 1726–1747). (c) The oldest and longest precipitation annual record from Paris (1688–2018). (d) The oldest and longest annual record for number of rain days from Prague^–.