About average mean sea level pressure maps

How were the maps created?

The average mean sea level pressure (MSLP) maps are based on the NCEP2 (National Centers for Environmental Prediction) monthly re-analyses for the period 1979-2000.

Computer models are frequently used in the forecasting process. These models need to produce a snapshot of the current state of the atmosphere before they can produce forecasts. This snapshot is often called an "analysis", or if it is an analysis of past conditions, it is called a "re-analysis". It is these re-analysis fields which were used to develop the MSLP climate maps. Re-analysis fields are created based upon data from the world's national meteorological services (from ground stations, upper air observations, satellites, ships, buoys etc.). These data are fed into computers, checked for accuracy, and mapped onto a three-dimensional grid.

Monthly and annual averages were calculated from this gridded data.

The gridded data were then visualised in a geographic information system and the colour maps created through this process.

Data used in the analysis

The MSLP climatology used is based on the NCEP2 (National Centers for Environmental Prediction) re-analyses for the period 1979-2000.

The re-analysis is done at NCEP (formerly NMC) using T62 (209 km) global spectral model of 28 vertical levels. This is the same model used in the assimilation system, as implemented in the NCEP operational system in December 1994. The model has 5 levels in the boundary layer and about 7 levels above 100 hPa. The lowest model level is about 5 hPa from the surface, and the top level is at about 3 hPa.

For more information about NCEP see http://www.ncep.noaa.gov/

Mean sea level pressure metadata

The following metadata summary, and detailed metadata file, provide information about the average monthly and annual gridded MSLP datasets. For example, information is provided about the format, spatial extents and analysis techniques used to generate the grids.

The detailed metadata file provides more information about the mean sea level pressure gridded datasets, including information about the analysis technique. You can also find out about the other gridded datasets we have available.

Copyright & contact information

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

If you want to know more, please contact us at webclim@bom.gov.au