EKO MS-80 - Appendix; Radiometric Terms Definitions

EKO INSTRUMENTS CO., LTD. - Pyranometer MS-80/80S/80U - Instruction Manual Ver. 1
Pg. 42
APPENDIX
A-1. Radiometric Terms
Table A-1. Definitions of Terms
Hemispheric Solar Irradiance
Cosine-weighted solar irradiance received over a solid angle of 2πsr on a
plane surface, expressed in units of W/m
2
or kW/m
2
.
Global Solar Irradiance, Global
Horizontal Irradiance [GHI]
Hemispherical solar irradiance received on a horizontal plane surface,
expressed in units of W/m
2
or kW/m
2
.
Direct Solar Irradiance, Direct Normal
Irradiance [DNI]
Normal-incidence solar irradiance received over a small solid angle which
includes the circumsolar irradiance, expressed in units of W/m
2
or kW/m
2
.
Diffuse Solar Irradiance, Diffuse
Horizontal Irradiance [DHI]
Hemispherical solar irradiance without the direct solar irradiance, i.e.
indirect irradiance of the scattered solar radiation [by air molecules, aerosol
particles, clouds, etc.], expressed in units of W/m
2
or kW/m
2
.
Pyranometer
A radiometer designed to measure the hemispheric solar irradiance over
the wavelength range of about 300 to 3,000nm.
Pyrheliometer
A radiometer designed to measure the direct solar irradiance over a certain
solid angle including the circumsolar irradiance.
World Meteorological Organization
(WMO)
It is a specialized organization of the International Union that carries out
international standardization and coordination of meteorological work.
WMO: Abbreviation for World Meteorological Organization
World Radiation Reference
[WRR]
Radiometric reference instrument system which has an uncertainty of less
than +/-0.3%, expressed in SI units.
This reference is maintained by the World Meteorological Organization
[WMO], and it has been issued since January 1, 1980
ISO9060
An ISO norm [International Standard]. The first edition was published in
1990, then the second edition was revised in 2018.
Based on the performance of each characteristic, Pyranometer is classified
into three classes A, B, and C, and specifications of "Spectrally flat
radiometer" and "Fast response radiometer" are set as sub-categories.
Pyrheliometer is classified into 4 classes of AA, A, B and C based on the
performance of each characteristic, and specifications of "spectrally flat
radiometer" and "Fast response radiometer" are set as sub-categories.