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1 km Resolution UK Composite Rainfall Data from the Met Office Nimrod System

Update Frequency: Continual
Latest Data Update: 2023-06-19
Status: Ongoing
Online Status: ONLINE
Publication State: Published
Publication Date: 2003-08-31
Download Stats: last 12 months
Dataset Size: 6.86K Files | 251GB


1 km resolution composite data from the Met Office's UK rainfall radars via the Met Office NIMROD system. The NIMROD system is a very short range forecasting system used by the Met Office. Data are available from 2004 until present at UK stations and detail rain-rate observations taken every 5 minutes. Each file has been compressed and then stored within daily tar archive files.

The precipitation rate analysis uses processed radar and satellite data, together with surface reports and Numerical Weather Prediction (NWP) fields. The UK has a network of 15 C-band rainfall radars and data form these are processed by the Met Office NIMROD system.

Please note CEDA are not able to fulfil requests for missing data from this archive. The data may be available at a cost by contacting the Met Office directly with required dates. It is worth contacting the CEDA first to check if the reason for the gap is already identified as being due to the data not existing at all.

CEDA does not support reading software but programs written by the community to do this task in IDL, Matlab, FORTRAN and Python are available in the dataset software directory.

The data files contain integer precipitation rates in unit of (mm/hr)*32. Each value is between 0 and 32767. In practice it is rare to see a value in excess of 4096 i.e. 128 mm/hr.

At 10:00 on 14 June 2005, the 1 km composite data files became larger with 2175 rows by 1725 columns compared to the previous 775 rows by 640 columns. From 14:55 on 30 August 2006, the 1 km composite data files are gzipped files. From 13 Nov 2007, the 1 km composite is derived directly from processed polar (600m x 1 degree) rain rate estimates and there is more detail in the rain structure.

Citable as:  Met Office (2003): 1 km Resolution UK Composite Rainfall Data from the Met Office Nimrod System. NCAS British Atmospheric Data Centre, date of citation.
Abbreviation: Not defined
Keywords: Met Office, NIMROD, rain radar


Previous Info:
No news update for this record
Previously used record identifiers:
Access rules:
Restricted data: please submit an application using the REQUEST ACCESS link for access.
Use of these data is covered by the following licence: When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.
Data lineage:

Data are acquired from rain radar network in the UK and Europe by the Met Office's NIMROD system. Composite products (images and data) and single site data are then sent to the BADC by the Met Office's DART operational dissemination system. Raw polar data from single sites are sent through from the RADARNET team at the Met Office. On arrival at the BADC the data are ingested after a one day quarantine.

Data Quality:
Data are from the Met Office's operational NIMROD system
File Format:
NIMROD product data are in the non-standard NIMROD binary format. Refer to linked documentation for further details. However, the documentation does not indicate there are three 4 byte elements in each record. These are located before each block of data within the record, the first and second should be equal to 512 to confirm the size of the next data block; the third should be equal to twice the size of the data grid (e.g. if the data are in a grid 200 by 500 boxes, then this third entry should be 200,000)

Process overview

This dataset was generated by instruments deployed on platforms as listed below.

Instrument/Platform pairings

Met Office C-band radar Deployed on: UK Radar Stations
NIMROD system Deployed on: UK Radar Stations
Output Description


  • long_name: Precipitation Rate
  • gcmd_url:
  • gcmd_keyword: Precipitation Rate
  • names: Precipitation Rate,

Co-ordinate Variables

Temporal Range
Start time:
End time:
Geographic Extent

Related parties
Authors (1)
Funders (1)
Principal Investigators (1)