Abstract

Global solar exposure is the total amount of solar energy falling on a horizontal surface. The hourly global solar exposure is the total solar energy for one hour. Typical values for hourly global exposure range up to 4 MJ/m2 (megajoules per square metre). The values are usually highest in the middle of the day and around summer, with localised variations caused mainly by variations in atmospheric conditions, primarily cloudiness. See metadata statement for more information.
Google map showing geographic bounding box with values North bound -10.013967 East bound 153.949355 West bound 112.903114 South bound -43.660886
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Product Type/Sub Type

dataset - Database

Constraints

license
Creative Commons Attribution 3.0 Australia Licence

IP Owner

Bureau of Meteorology
Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

2013

Product Type

dataset

Topic Category

climatologyMeteorologyAtmosphere

Keywords

Database
GIS
solar
solar exposure
Meteorology

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-10.013967
East bound
153.949355
West bound
112.903114
South bound
-43.660886

Lineage

The Bureau of Meteorology's computer radiation model uses hourly visible images from geostationary meteorological satellites to estimate hourly instantaneous global solar irradiances at ground level. These estimates are then used to statistically estimate the monthly mean of the exposure over each hour of the day. At each location in 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 irradiances were produced by reprocessing archived raw satellite data using software that was extensively rewritten in 2006, but based on the two-band physical model (Weymouth and Le Marshall, 2001) that has been the basis of the Bureau of Meteorology's satellite solar radiation system since 2000. The irradiances are not corrected for any bias with respect to ground-based radiation observations. Each instantaneous irradiance is converted to an equivalent hourly exposure by assuming that the atmospheric transmittance, also known as clearness index, for the instant of the satellite measurement is representative of the one-hour interval. While such an estimate may have a large uncertainty for a particular hour, due to the lack of information on atmospheric variations within the hour, the mean of a large statistical sample will have a significantly smaller uncertainty. The monthly means presented in this dataset are averages of the values from 1990 to 2012 (23 years of data). Thus the mean for each specific month and UT hour of the day is an average of approximately 690 samples (about 30 days per month times 23 years). The hourly exposure gridded datasets cover Australia with a resolution of 0.05 degrees in latitude and longitude. For each of twelve months, there are grids for eighteen UT hours, labelled by the month and the end UT hour of the accumulation hour. The first and last accumulation intervals end at 19 UT and 12 UT respectively, so that the eighteen intervals are: 18 UT to 19 UT, labelled 19 UT 19 UT to 20 UT, labelled 20 UT ... 11 UT to 12 UT, labelled 12 UT The exposure units are megajoules per square metre. References: Weymouth G.T. and Le Marshall J.F. 2001. Estimate of daily surface solar exposure using GMS-5 stretched-VISSR observations. The system and basic results. Aust. Meteor. Mag., 50, 263-278.

Digital Transfer Options

onLine

DISTRIBUTION Format

pdf
gdb

Distributor

Role
distributor
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

cf1e952e-1a3c-145d-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

Metadata Date Stamp

2012-11-23

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Geoscience Australia
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
Downloads
For information on acquiring this product,
please contact Geoscience Australia Client Services via:

fax:
+61 2 6249 9960; or
phone:
1800 800 173 (within Australia);
 
+61 2 6249 9966 (outside Australia).