Instrument Debrief for HAMSR
Sortie Number: 05-9024
Instrument Performance:
HAMSR performed very well. The overheating problem seen at Dryden was fixed before the ferry flight. The fix worked, and we are not seeing any anomalous instrument temperatures.
We see a lot of signals related to convective activity. This is most apparent in the 183-GHz band, where scattering from large ice particles (like graupel) above convective cells causes very large brightness temperature depression relative to normal values - especially in the more transparent channels that normally see deep into the warmer part of the atmosphere but are shielded from doing that by a scattering layer above the convective cells. This usually also indicates heavy precipitation. In this sortie, we see brightness temperatures as low as 95 K - this is compared with normal values of 270-280 K for the more transparent channels (i.e. a depression of something like 180 K!). Just eyeballing a plot, it looks like we encountered that around 14:20. The 5 K ambient drop reported by the pilot at 14:31 seems to correlate well with another cell. (I don't have the track plot in front of me, but it is possible this is a repeat pass over the 14:20 cell.) It does not stick out as very different from the others, though, but it does show up in the temperature sounding bands, including the 50-GHz band (which takes some doing, since scattering effects are much less at those lower frequencies). The 50-GHz band shows a very large Tb depression around 15:10. We see depressions around 60-80 K in the more transparent channels, which is extremely unusual. The other bands also show the ususal scattering signature here, and it is close to being the largest event for those bands too. If I had to point to the most notable feature of this sortie, I think it would have to be the 15:10 event. We will post some quicklook data later. Bjorn
