NASA06
FSSP notes
J French (compiled 2/17/06)

The ‘old’ FSSP (ser# 413-0577-12) was used for the entire NASA06 project (3 test flights, 9 research flights). It was noted early in the experiment that the instrument was exhibiting ‘strange’ behavior during flights. However, attempts to reproduce this behavior on the ground were, generally, unsuccessful.

Problems with the instrument were sporadic and did not affect every flight. Only on a few occasions are data corrupted for an entire flight. In some instances the instrument appeared to work early in a flight but did not work later in the same flight.

Although the exact nature of the problem varied somewhat, in general, when the probe was not working, it reported a high number of total resets while at the same time reporting no strobes. It is believed this behavior resulted from fogging on one of the optic mirrors due to a heater problem. Between the flight on Feb05 and Feb09 corrosion was noted on a connector for the heater in one of the probe arms. The connector was cleaned and the instrument worked well for both remaining flights (Feb09 and Feb10).

Below is a brief synopsis of FSSP status for each flight:

Test flights:
0110b - FSSP working
0110c - FSSP working
0113b - all clear air
0124a - all clear air

Research flights:

0118a:

FSSP worked entire flight, favorable comparisons between LWC devices

0126a:

FSSP not working most (all?) of flight, early in flight (19:31-19:35) penetrated liquid water ~0.2 g m-3 based on PVM and DMT, FSSP showed droplets, but very 'spiky', shortly after this time, rest of flight indicated lots of resets but no strobes, no particles in other regions where PVM & DMT indicated LW ~ 2 g m-3; after flight Don checked with nebulizer, appeared to be working on ground

0127a:

FSSP works well entire flight, DMT turned on ~third way through flight (?...~21:55), maximum LWCs between 0.5 & 1.0 g m-3

0127b:

more difficult to determine, LWCs less than earlier flight on this day, max around 0.2 in PVM, 0.15 in DMT...FSSP picks up most of this, particularly early on, later in flight looks questionable, but LWCs are even less, stobes/resets ~ 0.1, typical for ice??

0131a:

FSSP not working this flight, no strobes, lot of resets, after flight Glenn checked with nebulizer and beads, was not working, cleaned and re-aligned mirror, noted broken heater wire but not sure if breakage occurred during disassembly & cleaning.

0202a:

FSSP is working for the first half to ¾ of the flight. After 2130 it appears that the instrument begins exhibiting problems consistent with the probe not working properly (high # resets, few strobes). However, even after 2130, LWCs computed from the probe show reasonable agreement with the PVM and DMT. I would still judge data taken after this period as ‘suspect’. Before 2130 the FSSP appears to be behaving quite well. LWCs computed from FSSP, PVM, and DMT compare favorably.

0205b:

FSSP does not work correctly virtually the entire flight. Within 30 minutes after takeoff, the probe begins reporting high # resets with essentially no strobes. Only in the first ½ of flight do comparisons of LWC between FSSP, DMT, and PVM look reasonable. After this time, FSSP does not even appear to respond to regions of liquid water (as identified using data from the PVM & DMT).

0209a:

FSSP works entire flight

0210a:

During this flight, the ‘new’ FSSP was also flown (new probe in OBL, while ‘old’ probe remained in IBL). The old probe appeared to work well entire flight. Comparisons between the new and old probe reveal the new probe reports roughly 2X the number of resets, strobes and gated strobes as does the old probe. Particle size spectra agree quite well, except for number concentration. Consequently, the LWC for the new probe is roughly 2X that reported from the old probe.