DOI: 10.23637/rmstmarain1853-2024-01
title: Dataset: Total Monthly and Annual Rain at Rothamsted 1853-2024

description: This dataset contains the total monthly and annual rainfall, at Rothamsted from 1853 - 2024 and is based on continuous daily records measured at the site. The chart shows the annual data for illustrative purposes and the complete set of monthly data (and annual data) is available in the downloadable data file.
description: Daily rainfall is measured as the total (mm) over the 24-hour period 0900 to 0900 GMT. It includes all precipitation - snow, rain, mist and fog. Rainfall was first recorded at Rothamsted in 1853, using a copper funnel rain gauge (5 inch / 12.7 cm diameter) and measured using a graduated cylinder. Data was collected daily, manually, until 2004 and since then by Automatic Weather Station using a standard protocol. From December 2004 - September 2020 it was measured using an electronic tipping bucket rain gauge (10 inch / 25.4cm diameter), ARG100, calibrated to tip at 0.2mm (which has since become the minimum amount of rain that can be recorded). The rain gauge was within a 30cm deep 1.5m radius turf wall, retained by brick, to reduce wind eddies that may potentially blow rain out of the gauges. Since Sept 9th 2020 it has been recorded with an SBS500 tipping bucket rain gauge, funnel diameter 25.2cm and calibrated to tip at 0.2mm, manufactured by Environmental Measurements Ltd (EML), supplied and calibrated by Campbell Scientific. It is no longer sited within the turf wall, as the aerodynamics of the gauge means that it should not be affected by wind eddies. The old 5 inch manual copper rain gauge is still used to manually measure precipitation fallen as snow when the tipping bucket rain gauge is blocked with snow or ice. 

NOTE 1. There is a slight discrepancy in the amount of rain measured by the ARG100 rain gauge between 10/12/2003 and 09/09/2020 a correction factor is advised for these data.

NOTE 2. Rain recording started at Rothamsted in March 1853 and thus the total for that year is for 10 months March-December. 

NOTE 3. Early records have been converted to millimetres (rounded to one decimal place) from inches.

NOTE 4. There may be variations when compared to the previous dataset owing to inclusion of new information or corrections
description: An Excel file containing monthly and annual total rainfall for each year, and charts of these data. 

There are a few missing days of records in the 19th century and early/mid 20th century - these are indicated with a highlight. Days with records are also provided. This may be because a 'trace' of rain, snow, mist, dew or fog was manually recorded. A 'trace' is less than 0.05mm. For most purposes a missing value can be assumed to be zero. 0.05 mm tended to be recorded as 1mm.
description: Location: Rothamsted Meteorological Station, Harpenden, Hertfordshire, England 51.82 N 0.37 W 128 m asl. 

Over time, there have been changes to the rain gauges used:
06/02/1853-1948; 5 inch (12.7cm) diameter (cylindrical gauge), at ground level.
1948-11/12/2003; MK2 5 inch (12.7cm) diameter (cylindrical gauge), in turf wall.
11/12/2003-09/09/2020; ARG100 10 inch (25.4cm) (tipping bucket, hourglass), in turf wall *
09/09/2020-present; SBS500 9.9 inch (25.1cm) (tipping bucket, hourglass), at ground level. 

* this gauge (manufactured by EML, supplied and calibrated by Campbell Scientific) has been identified as capturing slightly more rain than the previous and the subsequent gauges. Therefore a correction factor (CF) is suggested, see ReadMe page for details. The CF advised is to divide the ARG100 data (11/12/2003-09/09/2020) by 1.1098 to match 5-inch and MK2 data (1853-2003).

These gauges can be seen in photos in the 'Media' tab of the web page.
description: The summary data contained in this spreadsheet are derived from daily data measured at Rothamsted Meteorological Station, Harpenden. Verification includes checks for instrument errors, for missing data and outliers. This dataset is compiled by Tony Scott and Sarah Perryman from the original raw daily data which is available, after registering, from the e-RA database. Please contact the e-RA Curators for an access password and further details.

We acknowledge the many weather recorders who have contributed to the collection of these data over the years, starting with Thomas Wilson and Edwin Grey in the 19th century including; Dave Yeoman, John Croft, Bob Norrish, Chris Hall, Paul Hargreaves, Helen Martin, Alan Thornhill, Phil Styles, Andrew Hunt and others.