Gridded average rainfall percentage metadata

Dataset

Title High resolution mean monthly and three-monthly rainfall percentge data (base climatological data sets).

Custodian

Custodian Bureau of Meteorology
Jurisdiction Australia

Description

Abstract Mean monthly and three-monthly high resolution rainfall grids.
The grids show the rainfall values across Australia in the form of two-dimensional array data.
The mean data are based on the standard 30-year period 1991–2020.
See LINEAGE below for more information.
Search Word(s) Gridded, analyses, rainfall, climatology, meteorology
Geographic Extent Names(s) Australia
General Category Gridded monthly data
General Custodian Jurisdiction Australian Government
Australia
Geographic Extent Polygon Not applicable
Geographic Bounding Box See below
North Bounding Latitude -9.975
South Bounding Latitude -44.525
East Bounding Longitude 156.275
West Bounding Longitude 111.975

Data Currency

Beginning Date 1991
Ending Date 2020

Dataset Status

Progress Completed
Maintenance and
Update frequency
As required

Access

Stored Data Format NetCDF (network Common Data Form)
Available Format Type NetCDF & Arc-ASCII row major format
Access Constraint

Please note that the copyright for any data supplied by the Bureau of Meteorology is held in the Commonwealth of Australia and the user shall give acknowledgement of the source in reference to the data.

Apart from dealings under the Copyright Act 1968, the user 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.

Data Quality

Lineage

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 estimate 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 Information

Contact Organisation Bureau of Meteorology
Contact Position Climate Data Services
Mail Address PO BOX 1289, Melbourne 3001, Australia
Locality  
State Victoria
Country Australia
Postcode 3001
Telephone (03) 9669 4082
Facsimile (03) 9669 4515
Electronic Mail Contact us climatedata@bom.gov.au

Metadata date

Metadata date 2020
Further information 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.
Additional Metadata These grids are based on monthly rainfall data - additional information available on request (see contact above).