Gridded monthly rainfall metadata
|Title||High resolution monthly rainfall total gridded datasets from 1900 onwards.|
|Update frequency||The latest month's grids are scheduled on the last day of the month, 3rd , 7th and 21st of the month|
|Custodian||Bureau of Meteorology|
|Abstract||Monthly high resolution rainfall grids.
The grids show the rainfall values across Australia in the form of two-dimensional array data.
The data extend from 1900 onwards.
See LINEAGE below for more information.
|Search word(s)||Gridded, analyses, rainfall, meteorology|
|Geographic extent names(s)||Australia|
|General category||Gridded monthly data|
|Geographic extent polygon||Not applicable|
|Geographic bounding box||See below|
|Domain and grid resolution||Two grid resolutions provided:
Native (original) resolution is 0.01 degrees (approximately 1 km) – available on request,
A grid averaged resolution of 0.05 degrees (approximately 5 km) – available via public webpage
|Domain°(0.01 degree resolution)||111.995°E – 156.255°E; 9.995°S – 44.505°S.|
|Domain°(0.05 degree resolution)||111.975°E – 156.275°E; 9.975°S – 44.525°S.|
|Maintenance and update frequency||Ongoing|
|Stored data format||.nc(zipped), Arc/InfoTM grids - all Australia|
|Available format type||ASCII row major|
Please note that the copyright for any data supplied by the Bureau of Meteorology is held in the Commonwealth of Australia and the purchaser shall give acknowledgement of the source in reference to the data. Apart from dealings under the Copyright Act 1968, the purchaser shall not reproduce (electronically or otherwise), modify or supply (by sale or otherwise) these data without written permission from the supplier.
Please contact us (see details below) for more information.
Use of these data should be acknowledged to the Bureau of Meteorology.
The analyses (grids) are generated using statistical interpolation (Gandin 1963; Lorenc 1981), which is basically a form of least squares regression applied in two dimensions. Often referred to as optimal interpolation (Daley 1993), the technique yields estimates of grid-point values from a weighted sum of observation increments to a background value. In the analysis of monthly rainfall, the background value is related to the monthly climatology (a reasonable first-guess of the rainfall in a given month), and is set at 0. Correspondingly the increments are the anomaly-ratio of monthly rainfall, formed from the difference of the rainfall from the monthly climatology, relative to the monthly climatology. This way the background value has a zero mean.
The background error correlation and background error variance (BGE) form the most important elements of statistical interpolation, which are determined from interstation correlations for each month, across the climatology period 1981 to 2010. For a given realisation, the observation increment is spread out according to the spatial structure of the respective BGE for that month. This means that the level of accuracy is expected to be better in data dense areas and degrade to those defined by the BGE in areas of data sparseness.
To effectively account for low network density in parts of Australia, two passes of the statistical interpolation technique are applied (following the method of Glowacki et al. 2012), first at a low resolution (0.25 degrees) and a second time at the final resolution of 0.01 degrees. The first pass generates pseudo-observations in data sparse regions, which are limited in their inclusion, by sampling the grid at 2 degree intervals. Pseudo-observations have little or no evident impact on the final resolution analysis away from data sparse regions in Australia's interior. The resulting rainfall anomaly-ratio grids are converted back to rainfall totals by adding one then multiplying by the monthly rainfall climatology. See Evans et al. (2020) for full details of the analysis scheme.
|Positional accuracy||The observational (station) data on which the analyses were based have an associated accuracy of the order of 0.01 degrees (approximately 1km) or better.|
|Attribute accuracy||Not applicable|
|Logical consistency||Not applicable|
|Completeness||No missing data|
|Contact organisation||Bureau of Meteorology|
|Contact position||NCC Information Officer|
|Mail address||PO BOX 1289, Melbourne 3001, Australia|
|Telephone||(03) 9669 4082|
|Facsimile||(03) 9669 4515|
|Online/email||via feedback form|
|Additional metadata||These grids are based on monthly rainfall data. Additional information and high is available on request (see contact above).|
- Daley R. 1993. Atmospheric data analysis. Cambridge University Press, New York, U.S.A., 457pp.
- Gandin, L. S., 1963: Objective Analysis of Meteorological Fields. Gidrometeorologicheskoe Izdaltel’stvo, 286 pp.
- Glowacki, T.J., Xiao, Y. and Steinle, P. 2012. Mesoscale Surface Analysis System for the Australian Domain: Design Issues, Development Status, and System Validation. Weather and Forecasting. 27, 141–157.
- Evans, A., Jones, D.A., Smalley, R., and Lellyett, S. 2020. An enhanced gridded rainfall analysis scheme for Australia. Bureau of Meteorology Research Report. No. 41.
- Lorenc, A., 1981: A global three-dimensional multivariate statistical interpolation scheme. Monthly Weather Review., 109, 701–721.