The Sun has both direct and indirect influence on the
terrestrial system; and appropriate measurements of both total and
spectral solar irradiance provide the requisite understanding of one
of the primary climate system variables. SOLSTICE provides precise
daily measurements of solar spectral irradiance at ultraviolet wavelengths.
Even small variations in the Sun's radiation at these short wavelengths
lead to changes in atmospheric chemistry. Although the ultraviolet
radiation from the Sun varies by as much as a factor of 2, its measurement
requires access to space since this radiation does not penetrate the
atmosphere. Also, the variability of solar ultraviolet radiation over
an 11-year solar cycle is a strong function of wavelength, leading
to varying requirements for different portions of the ultraviolet
spectrum. The SOLSTICE measurements provide coverage from 115 nm to
320 nm with a spectral resolution of 0.1 nm, an absolute accuracy
of better than 5%, and a relative accuracy of 0.5% per year.
Table 1: SOLSTICE Properties
| Instrument Type | Modified Monk-Gilleison spectrometers |
| Detector Type | photomultiplier tubes |
| Wavelength Range | 115 - 310 nm |
| Resolution | 1 nm |
| Absolute Accuracy | 1.2-6% |
| Relative Accuracy | 0.2-2.6%/year |
| Dimensions (H×W×D) | 18.3 × 38.7 × 84.6 (×2) cm |
| Mass | 36.0 kg (total) |
| Power | 33.2 watts (total) |
| Nominal Data Rate | 738 bps (total) |
| Field-of-View | 1.5° × 1.5° (uncalculated) and 0.75° × 0.75° (calculated) |
