Flight Report - PELTI Research Flight, 18 July 2000

PELTI Flight Reports as pdf files:

Friends,

Attached please find reports on our last three PELTI flights. I'm sorry for the recent information blackout, but things were too busy to get the reports done until I had a chance to catch up during a hard down day yesterday.

As you can see, we're doing very well on the comparison of the three inlets. It's clear that the LTI brings many more large particles into the plane than either the CAI or the NASA (solid diffuser) inlet. The APS data is very informative in that regard, as are chemical analyses from the filters. I hope to get some processed data out to you today that will show you the kinds of comparisons we've done. One major question concerns double peaks in the volume distribution behind the LTI. The right peak is probably the result of enhancement of large particles by curving streamlines in the LTI, plus losses of still larger particles in the tubing behind the inlet. Interestingly, this second peak sometimes goes away (it did during a constant-condition FT leg!) and is not as noticeable when the LTI is operated in a modestly turbulent mode (which should minimize the enhancement that would come from curving streamlines).

We're not as far along on comparing the LTI output with ambient concentrations. It has been hard to get the internal FSSP-300 leak-free (it's in a tight spot) and there are questions about just how to interpret its counts due to its relatively non-uniform flow regime. The TAS comparison of inside and outside was delayed a bit, but we now have some good data that is being analyzed back in the lab. We plan several more TAS samples in the MBL, because our precision with Na analyses will give us a good test of the enhancement that could be responsible for that extra peak behind the LTI.

We plan to fly tomorrow - largely in sea salt - and again on Friday, when a big dust event that features large concentrations in the FT is due. With luck, we'll be on our way back on Saturday.

Barry

huebert@soest.hawaii.edu