16 September 1995
PH: Okay. To start the summary: this morning's flight was devoted to individual plume sampling in an area 100 miles or so south of Maraba. We looked at several, maybe 4 or 5, burns of primary forest fires that were certainly of wood, live wood, and undergrowth, rather than any debris from slash burning. So, there should be quite a few good samples there of emission factors from primary forest burning. On the first fire that we sample, we also traced the smoke as best we could up to the base of the stratocumulus and cumulus fractus and then we cycled up through the cloud getting cloud samples to up near cloud top. Went back down again, got a CCN sample just below cloud base, although the smoke at that point just below cloud base wasn't apparent on the particle measuring instruments.
On the way out of Maraba, we climbed to above the main cloud top, so we got a profile on the way out. About 30 miles out or so heading south, we went back down through the cloud to the area where we did most of our sampling down to about 1,500 ft there. So, we had a couple of profiles through the main regional smoke layer. There is only one sunphotometer site in this region and that is 100 miles or so north of Maraba and it's in the no-fly zone for us. So, we can't do measurements directly over that sunphotometer. It's just to the west of the boundary that they've set for us that runs from Maraba to Belem. So, that's unfortunate.
We haven't seen any hot fires here today. It's mainly smoldering combustion quite a bit of it. Just one of the fires that we sampled, I forget which one, we saw some flames but they were mainly smoldering.
There's a lot of clearing going on in this area, perhaps as much as we've seen anywhere.
This is a big source region for the smoke that has been carried to the west during the last couple of weeks and would end up in the Porto Velho maybe down in the Cuiaba area that we were sampling earlier on. Ron, are you ready to summarize?
RF: Let's see. One, two, three emission factor samples, two of which were probably okay. Three background bags. Pretty high background today compared to what we've seen on other days. And none of those fires were particularly intense, so I think these are pretty marginal emission factors. And I guess I disagree with you somewhat in calling those primary forest fires. It looks like to me that they are just underbrush beneath the trees that are burning. And I don't know if that's designed to clear the underbrush and leave the trees or what, because it looks like the standing trees don't burn and the only burnt up trees you see are the ones they chop down first and then they'll probably burn a year later after they dry out.
PH: Yes, I agree. I said on the tape somewhere that it's probably primarily underbrush, but it's in the forest itself, unlike what we were sampling in Porto Velho where it was right on the edge and we were seeing burning of old trees that had been down for quite a while, so it's different from that at least.
Jack?
JR: Everything seems to have gone okay. I haven't seen anything go wrong with the instruments.
PH: Don, summarize.
DS: The CCN functioned pretty well this flight. Towards the end it was getting pretty warm. It's starting to go down but I guess we'll be fine. The blue ice has warmed up too. The concentrations in the background air were around 400 or 500 cm-3 in the high supersat. channel, in the smoke it varied between 11,000 and 20,000 with the diluters thrown in. And it was pretty consistent in the same plume and the background air was also quite consistent. TDDR worked fine and everything else is ready for the next flight.
PH: Okay, good. Ron, what did you get on the DMPS?
RF: A lot of hot and cold samples, usually on the same bag whenever we sampled the source. And I think for the background sampling we were doing hot and cold on alternate bags, but it's the usual thing we've seen where the number doesn't decrease very much but all the sizes go down about 20 or 30%.
PH: Okay. So, we've seen that consistently in all the fires we've looked at or have there been any exceptions to that?
RF: I can't say we've seen a good flaming fire yet. Usually on the smoldering ones in the background haze you see that.
PH: Okay. So, that's the summary of the flight so far. We're now heading back to Maraba.
Okay, let's climb up and go as far back as we can in the clouds.
KM: We would have to reverse course to do that. We'll be entering the control zone.
PH: Oh, you can't climb any more from here?
KM: No, can't climb here.
PH: Okay.
KM: Okay, we can give you a climb. I think we'll just do a little jog to the right and that will keep us out of there space.
PH: Okay, good. Just stay in as much cloud as you can.
KM: And how high do you want to go?
PH: Go through the middle of the clouds.<
These cloud that we are going through now are cumulus humilis for the most part, a few towering cumulus. We're going through the middle of them. At least the middle of the smaller ones. As far as the bigger ones are concerned, we are probably going through the lower third. In fact, at this point we are about 500 ft above cloud base.
KM: How long do you want to stay up here, Peter?
PH: As long as you can, Ken.
KM: Okay.
KM: I can give you about another 5 mins here.
LS: Peter, I guess we're going to have to drop down out of this cloud. We can't go on any further west until we get clear.
PH: Okay, fine.