11 September 1995
2:25 PM
PH: (Summary half-way through flight.) Okay. So, so far what we've done is we headed out from Porto Velho at low altitude to the region where we thought we would see some fires at Samuel. Didn't find any fires there, although pretty nice uniform smoke, old smoke. Then we climbed as we headed out towards this site where a large burn was reported on the satellite yesterday. Climbed to 10,000 ft. And then, because the smoke was fairly uniform when we reached that site, we didn't see any cumulus there to indicate any fire below. But, because the smoke was uniform we did three CAR turns to the right and two to the left looking down on the smoke. We are now heading north again to the closest cumulus that's popping up above the smoke level here.
4:11 PM
PH: Okay. We'll do our final summary. I've already summarized the first part of the flight. We tried some cumulus studies not very successfully. They were dying on us. Then we headed back to our original site near Samuel for individual plume studies and found a couple of plumes that we worked quickly. We should have got some good chemistry on them. And then we had to head back prematurely, because the airport closing down. Okay. Are you ready, Ron?
RF: Yes, we got a couple of bags, filter samples, for background while we were doing all the sampling around the cumulus. So I really loaded those up so that they could get good organic carbon on them. And then we got a pretty good sample on that smoldering fire. We had about 25 ppm of excess CO2. And then the flaming fire we did quite well on that sample. We had almost 60 ppm of excess CO2. So both of those should be very good samples for emission factors.
PH: Good. I should note that they were both the same sort of fuel, namely, felled trees that were pretty gray looking but one was smoldering and the second one was definitely flaming. Maybe some of the flaming, the black smoke, might have been due to using gasoline to light the fire, but we saw no one there and I can't really believe that they are using gasoline, at the price it is here, to light these fires. Did you get CCN samples and everything else, Ron?
RF: Oh, yes. We did quite a few hot and cold DMPS and we did them on both of the fires, I believe. I'll take a look at it in a minute. CCN, I assume, was okay. I didn't hear anything from Don.
DS: Yes, CCN is fine. It worked pretty well. Those last two plumes we had I had to, of course, put pollution filter in but no problem.
PH: Okay. Make a note of those particular CCN spectra for looking at to see if they differ from the ambient we have been measuring today.
DS: They differ from the ambient, in fact they are larger by a factor of 10 or 100.
PH: Okay. Good. Ray.
RW: Let's see. I took 50 "no-bags". Humidigram. Got good optical data of the regional haze and some pretty good extinction cell data I think on both fires. So that all looks pretty good.
PH: Art?
AR: Today's flight was characterized by moist conditions up through about 8,000 ft, which also corresponded to near the top of the haze layer which was sort of fizzled out between 8,000 and 10,000 ft. When we got on top, we looked around for any cumulus that might be associated with fires. And when we didn't see anything in the immediate area, we hustled off toward the northwest and sampled a complex of very vigorously growing cumulus congestus clouds, although they seemed to have hit a barrier around 15,000 to 20,000 ft, the very highest peaks of the clouds and subsequently very little precipitation was noted. We continued to sample those clouds, first sampling a few turrets near cloud top. Those topped out at around 10,000 ft to 10,500 ft. Then we worked our way downward to below cloud base. During that same time, this complex of vigorously growing cumulus congestus clouds fizzled out, broke up and completely died away rather unexpectedly, considering the fact that we began sampling them around 10:30 LT in the morning and by 11:30 LT they were just about completely gone. Subsequently, we went from cloud base up to cloud top and that's when we saw that particular complex had died away completely. We did sample some detrained air from time to time from these clouds, which may be of interest at a later time. Again, like so many of these heavy, smoky days such as today, the smoke played a role in permitting good fire or cloud selection because it was so heavy. The boundary layer of the convection in the morning, any way, was limited to the region below 2,000 ft MSL and as a result no cumulus were forming. The smoke plumes today went up maybe 500 ft or 1,000 ft above ground level and then became very stratified, reflecting the stability that was still present under dimly sunny skies.
PH: Okay, Art. You suggested in the flight that the cumulus may have dissipated because we had flown through it earlier, but I don't believe that we would have dissipated that cumulus.
AR: No, that's right, Peter. I was being facetious.
PH: In little cumulus that can happen, but not that large complex we were looking at.
AR: No, that's right. That's why it was facetious.
PH: Well, if you make a comment like that on the tape, it comes out as an impression rather than a joke.
AR: Yes, I suppose that's true. I'll have to watch it then.