A few flights in…

We got a couple of science flights into our first week in Longyearbyen, and then had to spend the weekend on the ground as a low pressure system moved northwards over Svalbard, accompanied by a fair bit of rain fall. Not the conditions of nice undisturbed Arctic stratocumulus or clear skies that we really want.

The last flight before the weekend nearly didn’t happen – there was fog filling the fjord and over the airport. Fortunately, that receded sufficiently for a takeoff late in the morning.

MASIN take off

MASIN taking off over a fog bank

We kept a close eye on it during the day as it pushed up across the airfield and then receded again, and called up the aircraft a couple of times to let them know it was still clear enough to land. If Longyearbyen gets fogged in, the only other place for them to go and land is Ny Alesund. In the event, by the time they came in to land, the fog had cleared from the airport, though there was still plenty in the fjord.

MASIN above fog

MASIN approaching Longyearbyen above fog in the fjord

We’ve had another two flights since the weekend, all reasonably successful. All the flights have been made pretty much due north of Longyearbyen, over the sea ice north of Svalbard at around 81N, 15E. Most flights have focused on the cloud properties, with one focusing more on the turbulent fluxes between the surface and atmosphere over broken sea ice.

sea ice

Broken sea ice with melt ponds on the surface

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News from the high seas

While we’ve been focused primarily on clouds, the other half of the ACCACIA field campaign is going on at sea, on the RRS James Clark Ross. The latest news from the JCR is that everything is working well. The ICE-ACCACIA team from Leeds have made 5 deployments of the surface micro-layer sampler, and are seeing interesting results on ice nucleating material collected from ocean surface. The aerosol team from Manchester are doing OK, but lacking very much to measure – the marine BL around the ice edge is very clean. Only the biologists are not getting much – there’s not much going on in the ocean surface layer so far.

There has been some larger-scale biology though – to the delight of all on the ship (and the envy of all of us in Longyearbyen) they had a close encounter with a polar bear. Lucy sent the photo below.

polar bear

Polar bear about 50m from the James Clark Ross. Off the SE coast of Greenland

First science flight

We got our first science flight in yesterday, flying north of Svalbard across the edge of the sea ice. At low level the air was fairly clear over open water, but a radiation fog over the ice prevented the aircraft from descending below 500ft. There were several think decks of cloud above however, and we worked in those after doing as much as possible at low level.

MASIN-brocken-spectre-1

A Brocken Spectre – rings of scattered light around the shadow of the aircraft.

As I write the aircraft is back up in the same area conducting our second science flight. Take off was delayed by fog at the airport this morning – it’s still hanging around in the fjord, and washing up against the end of the runway. I’m on watch to call the aircraft if conditions deteriorate at all and they need to come back early.

The approach in to Longyearbyen airport

The approach in to Longyearbyen airport

Back in the field

The ACCACIA team – or at least a subset of them – are back in the field. We don’t have the FAAM 146 aircraft on this campaign, but the BAS Twin Otter is back in Longyearbyen, and the BAS research ship the James Clark Ross is on its way north to make surface measurements.

The aircraft team in Longyearbyen this time round consists of Tom Lachlan-Cope, Russ Ladkin, Amelié Kirchgaessner, Alex Weiss, and Vicky Hamilton-Morris, all from BAS along with Al Howland the pilot, and Robert Metcalf the aircraft mechanic; also Ian Brooks, Barbara Brooks (Leeds) and James Dorsey (Manchester). We arrived late on Friday night, and spent the weekend settling in, unpacking, and installing instrumentation on the aircraft.

Russ installing the turbulence probe on the aircraft

Russ installing the turbulence probe on the aircraft

This morning (Wednesday) we conducted a shake-down flight to makes sure all the instruments are working – most of them are, though there are a few issues that need sorting out.Tomorrow is looking good for a first science flight.

view from cockpit and turbulent probe

The view from the cockpit – the boom sticking out in front is the turbulence measurement probe

Above is a view from the cockpit showing the turbulence probe mounted over the windows. This measures the turbulent airflow in the atmosphere, which coupled with measurements to temperature and humidity fluctuations, allows the vertical turbulent transport of heat, moisture, and momentum to be measured.

MASIN-on-the-ground

Barbara

Barbara sat in the back of the Twin Otter with laptop to control her aerosol instruments (in yellow rack at left)

A Polar Low Flight

A small delegation of atmospheric modellers from the University of Bergen had the possibility to visit the ACCACIA field campaign. With the idea that meeting experimental meteorologists and looking out of the window instead of staring at a computer screen would broaden our views we went off to Kiruna. My PhD-project is about the dynamics of polar lows, also known as arctic hurricanes. These winter storms are well known by local fishermen and people living along the north-west coast of Norway for their sudden appearance and are usually accompanied by heavy snowfall and hurricane force winds. So far March had been a month of high polar low activity, including the period of the ACCACIA field campaign. Despite the focus of the campaign on aerosols and clouds, there’s always a chance that other meteorological features can become the target for the day.

Plan B became reality: we went off to fly into a polar low! There was a remarkable agreement between the met.no forecast and the latest satellite overpass, so we were very likely to actually find the polar low (usually the forecast and reality don’t match that well). It was my first flight on a research aircraft and this plane looks like one big instrument, everywhere on the outside there are instruments mounted and the inside has some seats, but most of the space is occupied by instrument racks and screens.

Flight Manager

Steph & Matt at the flight manager’s console

After take-off from Kiruna we headed straight to the polar low area. First two legs in the polar low zone were at high altitude, zzzzzzhp and another dropsonde is doomed to have a seaman’s grave… We dropped 11 of those, providing us with a nice glimpse of the state of the atmosphere, and than descended to finish with two low legs. Really low legs: approximately 100ft over a rough ocean state: high demand flying for the pilots (and too bumpy to take pictures), as far as I know this is one of very few direct measurements of the surface fluxes in a polar low. As the dropsonde data indicated, and now confirmed by looking out of the window: we were at the right location. Flying into wind speeds around 25 m/s and looking down at rough sea states, which changed suddenly into a calm and cosy ocean with wind speeds around 5m/s. A remarkable change, often mentioned by fishermen: it looks like a black wall is coming towards you and within a few minutes there is a transit from calm conditions to severe storm…

Annick Terpstra

A typical day (2)

For most of the science team flying days start about 5:30am, getting up to check the latest forecasts and to grab the most up to date sea ice data and satellite imagery of cloud cover. Satellite imagery and retrievals of sea surface temperature and chlorophyll concentration are provided by NEODAAS – we email a subset of these out to the team on the research ship to help guide their sampling too. The aircraft ground crew and many of the instrument operators have a much earlier start. Pre-flight preparation starts 4 hours before take-off: 5am for most of the ACCACIA flights.

146 startup

The 146 being started up ready for flight

Just over an hour before take-off we all meet in the operations room at the airport for a quick briefing to ensure everyone knows the plan for the day; then it’s all aboard ready for the flight. Almost all our flights have had a 9am take-off from Kiruna. Although we’re primarily interested in low-level process for ACCACIA, measurements start straight away.

Flight manager

Matt Gascoyne at the flight managers console

Our area of interest is mostly over sea ice around Svalbard; this is around a 2-hour transit from Kiruna. In order to maximise our science time, we stop for a refuel at Longyearbyen. Depending on the plan for the day, we may do some science on the approach to Svalbard – releasing dropsondes to measure the vertical thermodynamic structure of the atmosphere, and mapping the cloud field with a lidar.

Approach to Longyearbyen

View of the approach into Longyearbyen from the flight deck

Once in the operational area the aircraft flies a complicated pattern of ‘legs’ to measure the vertical and horizontal structure of the boundary layer, cloud, and aerosol. The science is directed by the ‘mission scientist’ who sits up front just behind the pilots.

Mission scientist

Me in the mission scientists position up front

While the mission scientist has a laptop on which to view some of the measurements as they are made, they rely heavily on the rest of the team to keep them informed of the full array of measurements in real time. Very often we end up changing our original plan in the light of the conditions we actually find – this can take a lot of quick thinking, and good information and advice from those down the back. Flight time is expensive (over £100 a minute) so we can’t afford to take our time thinking about what to do next.

Jim McQuaid at filters

Jim McQuaid at the filters instrument rack

Kelly downloading data

Kelly Baustian downloading data from the low-turbulence inlet system at the filters rack

The main cabin is packed with instrument racks, and a science team of anything up to 19 people. FAAM provide a core team of instrument operators, and university or MetOffice instruments usually have their own operators. Then there are a handful of people who don’t have specific instruments to deal with, but monitor the real-time data and keep the mission scientist informed. Everyone keeps some sort of log or notes of what’s going on – these are eventually compiled to provide a detailed set of notes on each flight to help interpret the data during later analysis.

Angela at core cloud console

Angela Dean at the core cloud microphysics console

cloud probes

Cloud microphysics probes beneath the wing

Discussing clouds

Discussing cloud measurements with Ian Crawford

After the flight, a quick debrief and chat with the team on the ground to discuss what went well, what problems occurred, and to see what’s planned for the next day. It’s usually about 8pm by the time we get back to the hotel – time to find some dinner, a well-deserved beer, and an early night ready to start all over the next day.

post-flight

A post-flight discussion between Ians Brooks and Renfrew

 

A typical day (1)

Two thirds of the way through this field campaign, and we’ve settled into a routine of sorts. The planning of a research flight starts the day before with a careful examination of a wide range of forecast products. The MetOffice are providing us with customised forecast maps – generated from their global operational forecast model – of both the whole of Northen Europe up into the high Arctic, and close ups of the Svalbard region. They are also running a high resolution (4km) model of just the Svalbard region. The maps include winds at various altitudes, cloud, precipitation, visibility, and surface pressure. We also grab the publically available forecasts from the Norwegian meteorological service, and take a look at various other freely available forecast products from different models around the world. We also use satellite retrievals of daily sea ice extent (University of Bremen sea ice group) to help plan where we need to be.

around the planning table

Gathered at the operations room to discuss plans

In order for the aircrew to file a flight plan, we need a pretty good idea of what we want to do tomorrow by about 10am, and a more detailed plan with precise locations and a summary of the nature of the flight legs required by about midday. The forecast team – the scientists who will fly the mission – start planning by 8am, soon after the latest forecasts become available. When the weather is more or less what we want it is easy to plan, and we can finish everything in a couple of hours. When conditions are less ideal it take a lot longer; carefully considering various options, and trying to balance how far away we operate – and hence the time we get on task – against the quality of the science we expect to get out of the flight. After all that effort things often change on the day – the weather forecast isn’t always right, which is why we’re here in the first place.

After sorting out the plan for tomorrow, the afternoon is spent completing summaries of the previous flights, looking further ahead at the options for the next few days, and trying (and usually failing) to catch up on non-ACCACIA work, answering emails, etc.

Discussion

Discussing the forecast

The science team has been split into two groups who alternate on flights. In late afternoon, those not flying often head down to the airport to meet the team flying today to see how it all went, and brief them on the plans for the following day or two. There is a tiny bit of friendly rivalry about which team is getting the best cases.

New forecasts come in during the early evening, so we give those a quick check in case they differ significantly from the ones we based our plans on, and then it’s off for dinner and an early night ready for an early start in the morning.

FAAM 146

The FAAM aircraft in the hanger at Arena Arctica