Yesterday we had the right levels of smoke pollution for our study (we want to find out how air pollution changes the behavior of clouds), but there was not enough energy in the atmosphere to make the clouds rise to the levels where water clouds become ice clouds. Since we want to get a complete cloud profile, we had returned a little disappointed last night. Today, we were a bit anxious about running into the same problem again, and made contingency plans for alternative flight regions, but we decided to start with the same study area as yesterday, south of Alta Floresta.
The morning started like most mornings in Manaus: A little bit of low-to-mid-level cloud in the sky, some small cumulus developing around 0930L. We took off at 1447Z (10447L) climbed towards FL390. With some relief we noted that there were not the big cells already dominating the sky like yesterday, but more active development of mid-size cumuli. That’s a good thing, because these big cells tend to drain all the energy from the atmosphere in their surroundings, leaving nothing for the “middle class”, which is what we want –dare- to fly into.
At about 1600Z, we descended again to be at low level near Alta Floresta, and at 1614Z we entered the smoke-polluted boundary layer at 15,000’. Some fires were visible, but no really big ones. Cloud base was at about 6200’, and once close to the ground we were flying over the huge areas of deforestation that are characteristic of the State of Mato Grosso. Soon we got really excited - a fire below was producing a plume of smoke that was growing into a nice, mid-sized cumulus. We actually managed to target this cloud several times and made some successful passages through it. – I’m sorry to be so enthusiastic about air pollution, but that’s what we are here to study!
The cloud development looked quite promising in this area, and we decided to give it a go here, instead of moving on to our contingency region. At 1654Z we began our usual procedure of cloud profiling, climbing and descending, turning in all directions to fly through the clouds at just the right spots. It’s like Goldilocks: Not so far into the cloud that things start shaking too wildly, but far enough to get good data. This time we managed to get a nice fresh outflow from a cumulonimbus cloud at 35,000’. Flying below the clouds we learn what the clouds suck in from the boundary layer, flying in the outflow we find out what they spit out into the upper troposphere.
We were done with the cloud profiling at 1937Z, turned towards Manaus, and climbed to 41,000’. On the way back we sampled ice crystals in the large regional outflow “soup” and landed again in Manaus at 2109Z. This flight had been a total success, and everybody went back to the hotel with a sense of accomplishment.
(Thanks to Pilot Steffen Gemsa for contributing some of the pictures)
The central idea of ACRIDICON is to compare the interactions between aerosols, cloud, rain, and radiation in clouds that are meteorologically similar, but contain different amounts of aerosol particles. We have so far sampled moderately polluted clouds (AC07) and fairly clean clouds (AC09). Now we are hunting for really dirty clouds. One thing I had never expected in the Amazon dry season: That finding really polluted air would be a problem. In previous campaigns, there were so many fires producing so much smoke that one could almost cut the air with a knife. I remember a morning in Ji Parana in 2002, where I woke up in the hotel room, smelled smoke, went into the hall way and, looking down the hall, saw smoke haze. I first thought the hotel was on fire, but it was just the heavy smoke that covered the whole region!
Well, this year we have to look pretty hard to find really polluted air. It appears that deforestation has really gone down in recent years, and that this shows up in improved air quality. A good thing for everybody, of course, except for us smoke hunters! We are further constrained by the area that we are allowed to operate in and by the need to find just the right kind of convective clouds. This makes flight planning a bit of a gamble, especially since weather forecasting in this region is not as reliable as one would like, to put it mildly.
Today, we put our bets on an area south of Alta Floresta, where the satellites had seen a large region of smoke, not very heavy, but good enough. The forecast was not for very strong convection, but we were willing to take a chance. HALO took off at 1052L and passed through a mix of clouds. Soon we saw nicely developed cumulus to our east, and even some threatening-looking giant Cb. Promising, but here the air was too clean for our purposes.
When we reached Alta Floresta, the air was dirty enough, but there were hardly any clouds! We flew over large deforested areas, and saw a few smallish fires. But, one of the actually had its smoke plume rising into a little cumulus cloud – a pyrocumulus! Even though it was small, we got quite excited and sampled through it. By this time (1250L), the clouds had started to develop quite nicely, and we began our cloud profiling routine. We went through cloud after cloud, getting shaken around, turning sharply again and again to get back into the next cloud, much to the discomfort to our Air Force observer who got quite airsick!
BUT – the strong inversion that was present at about 15,000’ made it difficult for clouds to rise through this level. Some valiantly pushed through and reached as much as 18,000’, but quickly collapsed, exhausted from their effort. It seemed that just as soon as we had made a passage through a cloud, it fell apart behind us. We joked in the cockpit that we were breaking the clouds with our airplane…
At 1515L it became clear that the clouds weren’t likely to rise any higher. Actually, there were beautiful clouds growing way higher just to the east of us – BUT – this was in a military area that we weren’t allowed to enter. How frustrating! We decided to head back to Manaus, collected some measurements in cirrus and outflow on the way back, and landed at 1652L. It was a great flight all in all, but we were still a bit disappointed because the clouds had fizzled out just below the level where ice starts to form, one of the phenomena that we are really interested in.
On this flight I took some pictures of the inside of HALO. There is one open area with a table, but the rest is packed with instruments. What a difference from the situation in the picture that was taken in 2006!
Pollutants in the atmosphere are transported horizontally by the winds and carried upwards by rising warm air and clouds. To find out the details of this transport, one can release small amounts of a substance that can be measured in incredibly minute concentrations in air samples. To do this, we went to the helicopter pad on top of the Park Suites hotel.
From here, one has a breathtaking 360-degree view over the Rio Negro, the Ponta Negra beach, the Hotel Tropical (left), and parts of Manaus. Standing on the edge of the heliport one gets a hollow feeling in the stomach...
The tracer was released from the heliport at about 06:00L and HALO took off at 10:40L.
The first part of the flight consisted of collecting air samples at low levels in the area where the models had forecast that our tracer would spread out to. Then came a comparison flight with the G1 aircraft in formation at low level.
On this day, there were lots of fires all over the area surrounding Manaus, which sent smoke into an otherwise relatively clean boundary layer and into the cumulus clouds rising out of it. Three more runs to collect air samples followed, to find out where the tracer was moving to as time went on. These runs were interspersed by a cloud profiling program, taking measurements of cloud properties at different altitudes.
Towards evening, the atmosphere showed remarkable layering, with the layers marked by haze or thin clouds. These layers were the product of air from the boundary layer flowing out of the top of clouds, bringing along pollution (carbon monoxide, aerosols, etc.) from below. At 17:40L, HALO landed again at Manaus’ Eduardo Gomes Airport.
The night in the hammock was short. At 0430 there were noises from the forest and soon also from the kitchen, and I found myself awake. Daybreak is actually a nice time in the forest – the air is still cool and there are lots of interesting calls from birds and monkeys. The most prominent is the call of the Screaming Piha (it must be the most inconspicuous bird with the most conspicuous call!). After breakfast and talking some science, I went again to the tower construction site in the hope of seeing some action, but only found the steel quietly waiting in the forest.
A great thing the ATTO crew has done recently is to build a boardwalk between the different lab containers. It makes moving around a pleasure instead of a muddy slog, and it preserved the soil and cover vegetation around the measurement sites.
One of the great joys of being at our tower sites is the opportunity to climb one of the walk-up towers into the forest canopy and get close to this amazing plantscape. Here also one has the best chance of seeing the forest fauna, which otherwise is always too far up to be seen. Usually, birding in the rainforest leaves you with a painful neck and steamed up glasses…
Climbing above the canopy brings one into another world again. Instead of the dark gloom of the understory there is bright sunshine up here, instead of the stifling still, humid air there is a cool breeze, instead of the enclosed sensation in the forest, an unending wide open space. Climbing up to the top at 80 m feels a little dicey, but is perfectly safe and the reward is a fantastic view over the Amazon forest.
Unfortunately, my high hopes for the local bird fauna were dashed. I saw a total of 7 (seven!) individuals, none of them well enough to identify. At least the class Arachnida obliged: When I saw a slight movement in the shadow of the tower to my side, I turned around and saw a beautiful tarantula cruising around the small platform that Eiko Nemitz’ ammonia measurement. Do spiders emit ammonia? We might find out!
At 1230, it was time again to leave ATTO, and another 5½ hour trip by foot, ATV, boat, and pickup truck brought me back to Manaus for the end of the science team meeting.
Since there was no flight planned for today and tomorrow, I took the opportunity to visit the Amazon Tall Tower Observatory (ATTO), a field site in the middle of the jungle 150 km NE of Manaus. This station is operated jointly by our Institute and the Brazilian National Amazon Research Institute (INPA), together with a large group of Brazilian and German partners. The centerpiece of the site is going to be a 325-m tall tower, from which measurements of trace gases, aerosols, and micrometeorology will be made. The project was initiated in 2008, but since planning and construction of the tall tower proceeded quite slowly, we decided early on to build a “Not-quite-so-tall Tower” (80 m high), and began measurements there in 2011. I wanted to see how the construction of the tall tower was progressing, and visit our resident science team.
The trip to the site takes about 5-6 hours, about 1-2 hours on paved roads, an hour on a dirt road, over an hour on a speed boat on the Rio Uatumã, and finally as much as an hour on a rough dirt road through the jungle, with some waiting times in between to make the connections. The dirt road is always a work in progress. In the rainy season, the lower part dissolves into a long lake of mud, and becomes unpassable even for jeeps. When we drove up from "Porto ATTO", our landing on the Rio Uatumã, to the observation station, we had to make serveral stops to get out of the way of road construction. All in all, I left Manaus at about 06:20 and made it to ATTO just for lunch.
The afternoon was spent looking at the construction site for the tall tower and looking at the three container labs that make up the present measurement site. At the moment, the “tall tower” is about 1 m tall, but all the foundations have been cast as well as the anchors where the cables will be attached that hold the tower. These anchors consist of concrete columns that go 6 m into the ground. All the steel for the construction is lying around the tower base in the forest, and we have been told that the actual tower construction will start this Thursday!
The container labs now are quite impressive. One lab houses the aerosol measurements. The air for these measurements is piped down from a dedicated 80-m mast that is placed directly next to the lab container, to avoid particle losses. A second container houses a variety of trace gas measurements, including ozone and nitrogen oxides. The third container is dedicated to high-precision measurements of CO2, CO, and CH4.
The day ended with a nice dinner (beans, rice, fish, meat, and salad) and discussions with the local science team over a few beers. Sleeping accommodations are in a jungle lodge, surrounded by mosquito netting, where everybody lies in comfortable hammocks.
Uli Pöschl from the Max Planck Institute for Chemistry, Mainz, who was an important member of our coordination group for the first half of the campaign, left this morning to return to Germany. Unfortunately, Danny Rosenfeld, another key member of the team was also called home today on a family emergency. So, this morning we had the last chance to take a picture of the steering group together.
(Today's blog comes to you courtesy of guest blogger Manfred Wendisch)
On Friday we had an exciting HALO flight with the objective to validate satellite measurements and collect data in and above the clouds. HALO was supposed to meet the high-flying satellite over the measurement area on its way southward, which requires an extremely exact timing by the pilots. Additionally, we wanted the meeting point to be at a certain altitude above nice convective clouds. It was almost unbelievable with which precision the pilots managed to fulfill this strange request! Actually, HALO was at exactly at the planned place above the clouds at the right time, amazing!
We took off 11:00 local time, shortly after the first cumuli started to pop up. It is always fun for me to watch these very regular visible signs of the beginning of convection each morning here in Manaus. You may almost set your wristwatch at 10 am because that time the clouds start to evolve each day. After take-off we flew northward and observed high cirrus clouds, which would make the comparison with the satellite measurements more complicated. We took it as a challenge and decided during the flight to try to reach the high cirrus and to even fly above it. Here the exceptional capabilities of HALO came into play; HALO can fly high and for a long time. Indeed we managed to reach a flight level of 45,000 ft; we even got over the cirrus top. This was an amazing experience, seeing the contrast between the dark-blue upper atmosphere and space and the bright cirrus.
After returning to lower levels, we chased convective clouds most of the rest of the flight. Air traffic control was very flexible and allowed the pilots to change levels and heading frequently to catch the most appropriate parts of the clouds. The pilots fly into the clouds only if their on-board radar indicates it is safe to penetrate. In this way we managed to sample almost 30 clouds on our 7-hour flight. Again, this was only possible because HALO offers such awesome possibilities of long endurance and high ceiling.
The collaboration with the pilots (Steffen, Michael) and the aircraft technician (Tommy) was just awesome, the whole crew including the PhD students operating the instruments in the back of the plane (Mareike, Frank, Thomas, Daniel) had a lot of fun and enjoyed the whole flight. We learned a lot and marveled what incredible clouds Mother Nature presents us here in Brazil. Look at the amazing pictures attached!
Don't worry, just a short entry: Believe it or not, the containers with our equipment, which had been held up in customs here since early August, were finally released TODAY!!! Thanks go to Bruno and Roberta for working hard to get this to happen. I won't bore you with the gory details of the story, which contains customs agents that fell ill, lost documents, and a couple of week of "The containers will be surely released tomorrow...".
Our Brazilian colleagues recommended that we should begin the exportation procedure TODAY. Good advice, I think!
The day started out sunny, with just a little bit of cirrus in the sky. By about 0830L, the vultures near the airport were testing the first slight thermals, but even they could not make it very high above the ground. By 0930, they had better success, and the first very small cumulus clouds showed up in the sky. After the usual hectic pre-flight period, HALO took to the sky at 1029 local time, or 1429Z.
Today, we wanted to investigate the behavior of clouds growing in clean air, and the models and satellite images had predicted that we would find good conditions for this purpose around Boa Vista, some 600 km north of Manaus. We performed a slow climb to 39,000’ through a moderately hazy boundary layer with about 600 CN/cc. At this time, cloud bases were about 3600’ and cloud tops reached 6000’. At 1456Z we arrived at FL390, stayed there for some 5 minutes and began our descent again into the BL. Some large cumulonimbus clouds to the NW looked like they reached above 40,-000'. The Cb in the image to the right could actually be seen on the Aqua MODIS satellite image, and we ended up sampling its outflow later in the flight (after 1831Z).
The highest tops were now at ~18,000’ and average tops at ~15,000’. In the BL, we found CN counts of 600-800 /cc. After turning south again near Boa Vista, we sampled the growing cu’s from cloud base at 3500’ up to 36,000’, and the headed southeast to sample the Cb outflow mentioned before. After about an hour of this, at 1912Z, we left this outflow, to fly to another large outflow from a beautiful, big Cb closer to Manaus (picture below). Here we were greeted by the noise of static discharge, a smoggy smell in the air (ozone? NO2?), and high particle counts (~4000/cc). A bit spooky, but very exciting to us! After 1954z we left this outflow, descended, entered the mixed layer at 14,000’ with CN ~550/cc.
On the final approach to Manaus airport, we flew along a huge and threatening looking thundershower. Good thing we were able to land before this came over the airport! Landing was at 2020Z.
The science crew today was Meinrat Andreae (Mission PI), Micael Cecchini, Florian Ewald, Mira Krüger, and Sergej Molleker.