Dark Current Monitoring and Correction for OMPS

The OMPS dark current monitoring/correction and transient detection algorithm will be described, and trending results presented. Dark current resulting from electrons thermally excited into the CCD conduction band constitutes a systematic bias that must be removed from OMPS sensor signals. While characterized prior to launch, the bias evolves post launch due to space weather effects and must be monitored and updated on orbit. Lattice damage caused by energetic particle hits results in pixels developing elevated dark current rates (becoming "hot"). The number of hot pixels on OMPS CCDs has increased linearly since launch at a rate of ~0.5% of all pixels / 100 orbits (~1 week). The mean dark current for hot pixels is 2-3 times that for undamaged pixels, but dramatic increases - greater than 800 times normal - are seen in some pixels. Failure to adequately update dark current characterizations, or to properly filter transient events in deriving dark current corrections, can lead to significant radiometric errors. Potential magnitudes and impacts on ozone retrievals of such errors will be estimated.