Data FAQs

Are PAR data available from the Bureau of Meteorology?

Photosynthetically Active Radiation (PAR) is the portion of the solar spectrum - from approximately 400 to 700 nanometres - which is utilised in the process of photosynthesis. This spectral band is a subset of the spectral band measured by the Bureau's pyranometers, and can be determined from observations using special instruments. Alternatively, when expressed as an energy, PAR may be estimated using an empirical relationship such as: PAR=0.45 * Global solar exposure (MJm^-2). For further information refer to, for example:

• Photosynthetically Active Radiation (PAR) as Observed from Satellites
• Relationships of Photosynthetically Active Radiation and Shortwave Irradiance by Papaioannou et al, Theoretical and Applied Climatology, 48, pp 23-27, 1993

Does the Bureau provide illuminance data?

Illuminance is the total luminous flux incident on a surface per unit area, where the luminous flux is the power of light weighted to correspond to the sensitivity of the human eye. The Bureau of Meteorology does not have illuminance data.

Can the Bureau provide Leaf Area Index data?

The Bureau of Meteorology does not provide Leaf Area Index data. These data, along with the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) can be obtained in a research-oriented spatial data format from the National Computational Infrastructure website.

Are Clearness Index data available from the Bureau?

The Clearness Index is a measure of the reduction in solar energy as sunlight passes through the atmosphere. It is equal to the ratio of global solar radiation on the surface of the earth to the extraterrestrial radiation at the top of the atmosphere, and can range from approximately 0.8 in the clearest conditions to near zero in overcast conditions. The Bureau does not provide measurements of Clearness Index.

Are UV data available from the Bureau?

The Bureau of Meteorology has a UV forecast service, but it does not provide observations of UV radiation. UV data from a number of locations are available from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).

Does the Bureau provide access to solar observations from other groups?

Not at this time. The solar data available from the Bureau of Meteorology are from its own ground observation network and from the Bureau's model which processes satellite images.

Can I obtain solar information from areas within the ocean or other large areas of water?

The Bureau's model to estimate solar exposure from satellite images currently does not process imagery over large bodies of water. However, during the processing of the imagery over land, the solar exposure is extrapolated approximately 50km from the coastline to include narrow peninsulas and small islands close to the mainland.

What causes the small regions of lower exposure I sometimes see on the solar exposure maps?

Large salt lakes can sometimes appear to have a lower solar exposure than the surrounding land. The computer model processes the whitish salt areas as if they were cloud, which would block some of the sunlight reaching the ground.

How frequently are the Bureau's solar data updated?

Daily solar data for locations via Climate Data Online, and daily gridded solar data and maps are nominally updated shortly after midnight each day.

Hourly solar grids and one minute solar data are updated at various times during the year. Please visit (or subscribe to) our Updates to One Minute Solar Data and Changes to Solar Data pages to keep informed of updates.