5. Required Support Measurements

The chemical ozonesonde will provide one means of ozone validation by in situ measurements. The vertical resolution of the ozonesonde is comparable to the ISP at 0.5-1 km, and the detector provides sufficient sensitivity for accurate measurements of ozone in the stratosphere.  In addition, a Brewer instrument will be used to determine column ozone density by means of moonlit measurements.  The Lunar Brewer requires only that the image is formed on a slit which provides for measurements of different phases of the moon with equal intensity.  The tracking requirements become more stringent with smaller phases of the moon, but these can be accommodated.  In order to use the Lunar Brewer within the same night as the mission, the moon must be at a sufficient height for at least one hour.  The optimal launch windows, corresponding to the presence of the moon (and no sun) with later blackout conditions for the NiteOwl mission, are *****.

Support measurements may be found in satellite measurements (e.g. GOME, TOMS) that correspond to the Churchill region within a reasonable time frame.  However, it is more likely that this mission will obtain vertical ozone profile validation from either the ground-based Brewer in Umkher mode or an ozonesonde which may be flown separately from the NiteOwl payload.  The ozonesonde is preferred due to its higher spatial and temporal resolution in the vertical profile.  

In order to determine other trace species concentrations, it is required that temperature or pressure be measured.  Although the inversion technique could also provide some measure of these parameters, several species are extremely sensitive to photolysis rate dependent on the temperature.  With this requirement on the precision of the temperature survey, it is best to provide a definite means of measurement.  A thermistor will allow the measurement of temperature in a simple, effective and reliable way that would not place significant burden on the cost or payload weight of the mission.