The Lusaka Leg

Operations base in Lusaka, Zambia

Flight planning at the operations base in Lusaka, Zambia

The final swamp survey of the campaign has just landed, so I thought this would be a good time for an update on our work here in Zambia. Since arriving on Wednesday we’ve conducted three flights over three different wetland areas, with each of them providing a rich, complex dataset for us all to get our teeth into when we get home. The Kafue river floodplain and the Bangweulu and Lukanga swamps all exhibited the telltale signs of strong methane emitters, with large concentrations enhancements observed during each flight. This large signal should make Rebecca’s life easier when determining source isotopic signatures (see “Meanwhile, back in the lab”), and we have started putting our heads together to determine the best ways of calculating how much methane each source area emits. While we won’t get into the nitty-gritty of the data analysis until we return, sitting together in the bar after a flight provides a great opportunity to foment some ideas.

The Bangweulu sortie was particularly special for me, as it was my first flight up in the jump seat as mission scientist 1. At first it seems like a daunting task, choosing where and at what height to fly in order to get the most out of the time available. However, with sage advice from veteran mission scientists beforehand, patience from the pilots, and help and encouragement from the rest of the team down the back, all went smoothly. Having surveyed the swamp, we flew back along a rift valley, hugging as close to the side wall as we could, looking for any sign of geological emissions. The data from this will need picking over in more detail before conclusions can be drawn, but from a scenery perspective this has to take top spot among flights I have ever been on. Looking up at the Muchinga Mountains from 1500 ft above the valley floor was a breathtaking sight for which I feel very privileged.

That leads me on to a topic that’s been covered many times in these blogs before, but now we’ve reached the end of the campaign I feel it bears repeating. These detachments are hard work, but the early starts and the weeks spent away from home don’t seem a hardship when you’re part of such a close team. As I write this we’re sitting out on the terrace with a Mosi in hand (other Zambia lagers are presumably available…) with impala wandering by, and I can reflect on friendships made and renewed. I’d completely echo Michelle’s earlier post – the rambling late night discussions, debates and arguments have been second to none, and I’ll certainly miss them when we leave. I’m looking forward to being home, but I’m looking forward to the next one too…

Farewell, and thanks for all the methane - Zwamps team

Farewell, and thanks for all the methane – Zwamps team

Smoking savannah fires from the first MOYA flight campaign

A few weeks ago, the MOYA team completed the first campaign on the Atmospheric Research Aircraft (run by FAAM). I was not in the field in Senegal, but instead I was doing weather forecasting, flight planning and monitoring of the data from back home in the UK. Although there was no wiggle room in the packed schedule, the team managed to get in 4 exciting science flights, and saw different things in each one! Here’s a rundown of what they got up to…

Photo Credit: Axel Wellpott.
Sampling over a forest fire in Senegal from the FAAM aircraft

On Tuesday 28 February 2017, they flew inland over a region of forest fires in Senegal. We wanted to sample the emissions from these fires, and they managed to do just that! The picture below shows some of the methane, carbon dioxide and carbon monoxide traces along the flight track. The big spikes show the places where they flew through the fire plumes. They saw huge spikes in all these gases – up to 500 ppb extra of methane, on top of the usual 1850 ppb in this region in this season. That’s about an extra 27%!

Measurements shown on a Google Earth map

Flight 1: Methane, carbon monoxide and carbon dioxide measurements from a flight over forest fires burning in Senegal shown on a Google Earth map.

We should be able to find out a lot about what gases and particles are in these fire plumes when we analyse these measurements – I’m not sure if anyone has ever flown directly over the fires to measure the emissions before! Some of the air inlets experienced a smoky smell and some strong turbulence from the heat from the fires, as well as a bird strike. All in the name of science!

Photo Credit: Euan Nisbet. Inside the FAAM atmospheric research aircraft

Photo Credit: Euan Nisbet.
Inside the FAAM atmospheric research aircraft – all eyes to the screens.

Next morning, the crew flew back over a similar region of the Casamance, and this time the visibility was very poor. You can see from the photo just how smoky it was. Sampling these fires two days in a row will allow us to find out how variable the emissions are from day to day.

Photo credit: Euan Nisbet. Smoke from the fires in the Casamance region of Senegal.

Photo credit: Euan Nisbet.
Smoke from the fires in the Casamance region of Senegal.

After refuelling in Dakar, the next flight was off the coast, with the aim of sampling fire emissions as they are blown out to sea. The measurements showed there were layers with high levels of ozone, carbon monoxide and nitrogen oxides as well as moderate methane, which may well have been from the fires. The figure below shows the carbon monoxide (CO) levels as the aircraft flew back and forth at different heights. At 5000 feet, there’s a layer of high CO that isn’t present above or below that height. The next day, they flew off the coast again and measured something similar, which one scientist called a “complex sandwiched air mass”!

Carbon monoxide levels along the flight track are shown by the colours. High levels at 5000 feet were sandwiched in between cleaner air.

Credit: Axell Wellpott.
Carbon monoxide levels along the flight track are shown by the colours. High levels at 5000 feet were sandwiched in between cleaner air.

Dr Grant Allen, one of the lead scientists on the flights, said of the experience:

“The flying was very challenging (and exciting!). Flying as low as 500 ft over the savannah and through intense fire plumes is a rare experience for most and I’ll admit to being nervous on occasion. However, the professionalism of FAAM and the expert training of the pilots and aircraft engineers means we are always in safe hands. The team recorded the most intense sampling (vertically) of a near-source fire plume ever performed with the FAAM research aircraft and the data will keep the science team busy for many months and years to come. We expect to analyse the carbon-isotopic fractionation of biomass burning signatures for this crucial regional methane source and provide new chemical and aerosol measurements of fire plumes.”

So started the first of the MOYA flight campaigns. We are all hoping we will have the same success and luck in the future!

– Dr Michelle Cain, University of Cambridge