Special Sensor Ultraviolet Spectrographic Imager (SSUSI)

The Special Sensor Ultraviolet Spectrographic Imager (SSUSI) is a space-based remote sensing instrument with a spectrograph and imaging mode that was developed to measure emissions in the ultraviolet (UV). In imaging mode, SSUSI measures emission across
the disk within five bands: Ly α [119 -124 nm], 130.4 [128-132 nm], 135.6 [134-137 nm], N2 Lyman Birge Hopfield LBHS [140-152 nm], and LBHL [165-180 nm].

CPI has been an active participant in each of the SSUSI calibration/validation programs (starting with the launches of F16 in 2004, F17 in 2006 and F18 in 2009). Work has focused on calibration and validation of dayside products and validation of auroral products. Calibration efforts have been directed to comparisons of SSUSI dayside data with TIMED/GUVI data and with radiances from CPI’s first-principals physics models. For F18, CPI has taken the lead on comparisons with coincident data from the Naval Research Laboratory’s (NRL’s) Special Sensor Ultraviolet Limb Imager (SSULI). Validation of dayside products has focused on comparisons of QEUV with independent solar measurements and of NmF2 and HmF2 with ground-based ionosonde data. Auroral validation efforts have been directed to comparisons of precipitation products (average energy Eavg and energy flux Q) with coincident data from SSJ/5 (on-board electron and proton particle sensors) and comparisons of NmE and HmE with incoherent scatter radar data.

 

SSUSI F16 auroral images for two of the three spectral channels used to
specify precipitation characteristics (the third channel is LBHS, shortward of
the LBHL channel). Contours of constant solar zenith angle at 90° and 100°
are displayed to identify nightside versus dayside observations.