Solar Spectra:
Standard Air Mass Zero

2000 ASTM Standard Extraterrestrial Spectrum Reference E-490-00

DOWNLOAD 2000 ASTM E-490-00

The Excell spreadsheet E490_00a_AM0.xls displays a plot of the two spectra showing very small differences.

NOTE: Before 2004-10-18 2200 UT the spreadsheet download was for a PRELIMINARY version of the E490 AM0
spectral standard. That spreadsheet had different" spectral step sizes and data values versus the PUBLISHED version of
the standard. As of 2004-10-18 2200 UT the workbook contains the current published table data.

Our apologies for any inconvienence this may have caused.

Contact Aron Habte (Aron.Habte@nrel.gov) if you have questions or concerns about this update.


TABLE 1: The Solar Constant in Alternative Units
Solar constant = 1366.1 W*m-2 [SI unit]
= 0.13661 W*cm-2
= 136.61 mW*cm-2
= 1.3661 x 106 erg*cm-2*s-1
= 126.9 W*ft-2
= 1.959 cal*cm-2*min-1 (± 0.03 cal*cm-2*min-1)
= 0.0326 cal*cm-2*s-1
= 433.4 Btu*ft-2*h-1
= 0.1202 Btu*ft-2*s-1
= 1.956 Langleys*min-1


The calorie is the thermochemical calorie-gram and is defined as 4.1840 absolute joules.

The Btu is the thermochemical British thermal unit and is defined by the relationship:

        1 Btu (thermochemical)/(°F*lb) = 1 cal*g (thermochemical)/(°C*g).

The Langley, however, is defined in terms of the older thermal unit the calorie*g (mean);
that is, 1 Langley = 1 cal*g (mean)*cm-2; 1 cal*g (mean) = 4.19002 J.


TABLE 2 Solar Irradiance at the Planets
  Planet Solar Irradiance, W*m-2
Mean Perihelion Aphelion
Mercury 9116.4 14447.5 6271.1
Venus 2611.0 2646.4 2575.7
Earth 1366.1 1412.5 1321.7
Mars 588.6 715.9 491.7
Jupiter 50.5 55.7 45.9
Saturn 15.04 16.76 13.53
Uranus 3.72 4.11 3.37
Neptune 1.510 1.515 1.507
Pluto 0.878 1.571 0.560


REFERENCES

(1) Fröhlich, C., and Lean, J., "Total Solar Irradiance Variations: the Construction of a Composite and its Comparison with Models," International Astronomical Union Symposium 185: New Eyes to See Inside the Sun and Stars, Kluwer Academic Publ., Dortrecht, The Netherlands, pp. 89-102.

(2) Woods, T. N., et al, "Validation of the UARS Solar Ultraviolet Irradiances: Comparison with the ATLAS 1 and 2 Measurements," Journal of the Geophysical Research, Vol. 101, No. D6, April 30, 1996, pp. 9541-9569.

(3) Neckel, H., and Labs, D., "The Solar Spectrum Between 3300 and 12500 Å," Solar Physics, Vol. 90, 1984, pp. 205-258.

(4) Kurucz, R. L., "ATLAS9 Stellar Atmosphere Programs and 2 km/s Grid," Harvard-Smithsonian Center for Astrophysics CD-ROM No. 13, 1993.

(5) Smith, E. V. P., and Gottlieb, D. M., "Solar Flux and its Variations," Space Science Reviews, Vol. 16, Nos. 5/6, November/December 1974, pp. 771-802.



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