Gridded average solar exposure metadata
|Title||Monthly and annual solar exposure (base climatological data sets)|
|Custodian||Bureau of Meteorology|
Global solar exposure is the total amount of solar energy falling on a horizontal surface. The daily global solar exposure is the total solar energy for a day. Typical values for daily global exposure range from 1 to 35 MJ/m2 (megajoules per square metre). For mid-latitudes, the values are usually highest in clear sun conditions during the summer, and lowest during winter or very cloudy days.
These average data sets are based on 30 years (1990 - 2019) of solar exposure data derived from Japan Meteorological Agency and National Oceanographic & Atmospheric Administration satellite imagery.
See LINEAGE below for more information.
|Search Word(s)||Gridded, satellite, climatology, solar, radiation, exposure, meteorology|
|Geographic Extent Names(s)||Australia|
|General Category||Gridded climatological data|
|General Custodian Jurisdiction||Australian Government
|Geographic Extent Polygon||Not applicable|
|Geographic Bounding Box||See below|
|North Bounding Latitude||-10.025|
|South Bounding Latitude||-43.975|
|East Bounding Longitude||153.975|
|West Bounding Longitude||112.025|
|Stored Data Format||Arc/Info grids all Australia, NetCDF|
|Available Format Type||NetCDF & Arc-ASCII row major format|
Satellite-derived solar global horizontal irradiance estimates are based on images from the Geostationary Meteorological Satellites GMS-4 and GMS-5, Geostationary Operational Environmental Satellite (GOES-9), the MTSAT-1R and MTSAT-2 satellites, and the Himawari-8 satellite, which are provided with permission of the Japan Meteorological Agency (JMA) and the United States National Oceanic & Atmospheric Administration (NOAA).
Any use of products from this imagery requires acknowledgement of the satellites of JMA and NOAA as the original source of the satellite data, and acknowledgement of the Commonwealth of Australia (Bureau of Meteorology) which received and processed the images.
Acknowledgement should be in the form:
Please contact us (see details below) for more information.
The Bureau of Meteorology's computer radiation model uses visible images from geostationary meteorological satellites to estimate daily global solar exposures at ground level.
At each location for each satellite acquired image, the brightnesses are averaged over each grid cell and used to estimate solar irradiance at the ground. Essentially, the irradiance at the ground can be calculated from the irradiance at the top of the earth’s atmosphere, the amount absorbed in the atmosphere (dependant on the amount of water vapour present), the amount reflected from the surface (surface albedo) and the amount reflected from clouds (cloud albedo).
These instantaneous irradiance values are integrated over the day to give daily insolation (daily radiant exposure) in megajoules per square metre. The daily exposure gridded datasets cover Australia with a resolution of 0.05 degrees in latitude and longitude.
The maps for this dataset were produced by reprocessing archived raw satellite data using software that was extensively rewritten in 2006 but based on the physical model that has been used since 1990. Bias with respect to exposure estimates from Bureau of Meteorology ground instruments was removed by a linear adjustment to each month's maps. The monthly averages have been adjusted (to reduce the effect of missing days as solar declination changes) using the ratio of top-of-atmosphere exposure totals for the full month and for the sampled days.
|Positional Accuracy||The satellite data on which the analyses were based have an associated resolution and typical accuracy of 0.05 degrees (5 km) up to and including June 1994 and 0.01 degrees (1.25 km) thereafter, although some individual images have errors of several km. For Himawari-8 the observation times follow a less regular progression with latitude and have a typical uncertainty of up to 0.5 minutes due to the satellite imaging the Earth in broad swaths, the fact that these swaths follow a complex pattern that is generally the same between images but can differ for some images, and the limited information on times available in the satellite data stream.|
The accuracy of the model’s daily estimates of solar exposure is estimated by comparison with measurements by Bureau of Meteorology ground instruments.
The source of uncertainties associated with calculations includes:
The model assumes that hourly (or less frequent) "instantaneous samples" of the irradiance will describe the conditions for the hourly (or longer) period.
All these factors with both random and biased components means that the 95% uncertainty for any of the daily solar exposure estimates, regardless of the averaging period (that is, daily, monthly and seasonal), is of the order of 3 MJ/m2.
For more information (metadata) please contact us.
|Logical Consistency||Not applicable|
All of the months for the period had at least half of their days sampled, with the vast majority missing no more than one day. The satellite data were acquired from the following satellites and instruments.
GMS is the Geostationary Meteorological Satellite series operated by the Japan Meteorological Agency.
GOES is the Geostationary Operational Environmental Satellite system operated by the US National Oceanic and Atmospheric Administration.
MTSAT is the Multi-Functional Transport Satellite series operated by the Japan Meteorological Agency.
VISSR is the Visible and Infrared Spin Scan Radiometer.
JAMI is the Japanese Advanced Meteorological Imager.
AHI is the Advanced Himawari Imager.
|Contact Organisation||Bureau of Meteorology|
|Contact Position||Climate Data Services|
|Mail Address||PO BOX 1289, Melbourne 3001, Australia|
|Telephone||(03) 9669 4082|
|Facsimile||(03) 9669 4515|
|Electronic Mail||Contact us email@example.com|
|Additional Metadata||Additional information available on request (see contact above)|