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

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The one with the ship in it…

On the RV lance, our days are alternately spent in open water and surrounded by mesmerising fields of sea ice. The ice takes many forms – glittering bright white sculptures rising from turquise pedestals, broken jigsaw pieces of a flat crust, slushy grey platelets, a near invisible film creeping over the water surface…The larger pieces bang and shriek against the thickened steel bows, behind which our labs are located.

As part of the ACCACIA project, some of us on board are investigating how biological and chemical processes in waters at the ice edge affect the atmosphere above. The spring melt of the ice brings with it a burst of life, as microscopic marine plants (phytoplankton) begin to multiply. To keep track of this change, we will measure the levels of nutrients and the plant pigment, chlorophyll-a, in the water. Anna Dimond is responsible for the round the clock collection and preparation of these samples.

Steve Andrews is analysing air and water samples on board, looking for atmospherically active trace gases such as dimethyl sulphide (DMS) and halocarbons that are produced by the phytoplankton. Between filtering and freezing samples, Anna is also finding time to test for levels of an enzyme implicated in the production of some of these gases.

I am isolating organic matter from seawater, and will compare the compounds I find to those in tiny airborne particles. To collect the latter, I have set up a sampler not unlike a vacuum cleaner on the highest deck of the ship. I hope to discover more about the nature and source of these compounds, as they are thought to affect the properties of the particles, and perhaps ultimately cloud formation.

CTD cast

A CTD cast underway

Each day begins with a CTD cast. A rosette of 12 ten litre bottles, plus an assortment of sensors monitoring temperature, salinity, pressure and light, is lowered over the side of the ship and down into the chilly water. In the ice, the water temperature reads -1.6 degrees Celsius. Once the rosette is back on board and secured in its heated tent to prevent it freezing up, our day of filtering, dripping and bubbling water begins.

Work is punctuated with three excellent hot meals a day, rivers of tea (our Norwegian crew have asked if it is healthy to drink so much!) and trips up to the bridge to scan the horizon for polar bears. We haven’t seen one yet, but are keeping our fingers crossed for the last few days in the ice, before we head back to Tromsø and home. We have seen some whales and dolphins though!

Rosie Chance

Whales and dolphins

Whales and dolphins

MASIN Flight 182

On board:  Al Howland (pilot),  Amélie Kirchgaessner (co-pilot/mission scientist), Barbara Brooks, Tom Lachlan-Cope

The intention of the flight plan was to measure high sensible fluxes at the ice edge in an area north of Svalbard, forecast by the Met Office model. Satellite imagery indicated cloud streets which looked like they would nevertheless allow a descent to low level. After a beautiful transit, we arrived in the area, to find that the clouds extended all the way down to the deck, so we could not get low enough to perform the flux measurements over open water. We did an 30-minute low level run at 100ft over the sea ice northwards, followed by a spiral ascend to 3000ft and a descend to 200ft heading back southwards along our track.

Fjord ice edge in Wijdefjorden

Fjord ice edge in Wijdefjorden

The next part of the flight was dedicated to aerosol measurements. Two legs were flown in the sea smoke parallel to the ice edge W-E at 100ft, returning at 150ft. At this point, due to strong tail winds, we were given additional science time. This was used to fly one leg W-E over the sea ice at 100ft, returning E-W at 300ft over the sea smoke of the open water. We then headed back towards Longyearbyen airport (LYR), flying a saw tooth pattern.  Both, top and bottom limit of the “teeth” were determined by the thickness of the cloud at the respective location.  After each ascent and descent respectively 2 minutes were flown straight and level. This brought us to the northern end of Wijdefjorden, where we descended to 100ft  under completely  cloud free conditions, to sample some turbulent fluxes over open water  before we reached the edge of the Fjord ice. We continued at low level for a scenic flight home, spotting some seals, a couple of walruses, and plenty of polar bear tracks, before we ascended to 5000ft for the transit back to LYR.

Amelie Kirchgaessner

Flight B760

Hello there, I am Rhiannon one of the ACCACIA PhD students and  will be updating the blog with our activities.

Thursday we flew flight B760 taking off just after 9am local time from Kiruna airport, headed to Longyearbyen on Svalbard via some science!

When we planned the flight Wednesday morning the forecasts showed a change between non existent or thin cloud over the sea ice East of Svalbard and then an area of convective cloud over the open sea. The winds were predicted to be light and flowing off the ice. The images below are an example of what we look at when planning, but we have many, many more forecast images at our disposal!

Planning Plots

Google Earth picture showing our proposed science sectors (yellow) and the sea ice extent (red). Plot showing pressure, cloud and precipitation forecast for Svalbard.

The aims were twofold, firstly to pass the ship RV Lance, which is also part of ACCACIA so we will be able to do inter-comparisons of data from the ship and the aircraft. Then after landing to refuel at Svalbard we were to fly to the east of the island and do a stack of passes going from the ice to the open sea at several heights. This pattern aims to establish the lower atmosphere structure and the transition from sea ice to water and look at the aerosol properties within the boundary layer and above the clouds.

This was my first time on the FAAM 146, and it is a bit different from a normal plane! Many of the seats have been removed to fit in racks of instruments, we have four point harnesses (a bit like a racing driver) for take off and landing and wear headsets to talk to each other. When you take your headphones off you realise why you need them, it is so loud! We do get in flight meals, but they came in a brown paper bag and were much more like a normal lunch than your standard aircraft fare (I very much enjoyed mine and even had a cake!)

There are instruments attached to outside of the plane or which take in air for analysis. This means you have access to almost live data when you are sat on the plane via your laptop connected to the on board network.

with all this data at your disposal you can quickly plot up many interesting things including tephigrams and windspeed plots or look at the mixing ratios of all sorts of chemical species, as well as keeping up with your current position.

I was sat infront of the York GCMS (gas chromatograph – mass spectrometer), which pulls in air and looks for a range of anthropogenic and biogenic volatile organic compounds (VOCs). I got to help out a little bit too!

On board the plane

My view on board the plane, lots of screen and headsets and tubes!Photo by Rhiannon Davies.

After about an hour and a half of flying we approached the RV Lance ready to pass by in an L-shaped pattern so we pass alongside and behind the ship.

We dropped down lower so we were in the best position for science and made our pass. The pilots spotted the ship first and then after about 5 minutes we passed by.

Passing the RV Lance.

Passing the RV Lance! Photo quickly taken by Jamie Minaeian.

It looks tiny!

We made a vaguely right angled turn as we had to avoid some weather and flew the second part of the pass. Then we climbed back up and approached Svalbard airport.

After a well executed landing on Svalbard, we were able to disembark while the plane refuelled. This was a welcome chance to stretch our legs and say hello to the BAS MASIN plane and its crew. Another research aircraft was in Longyearbyen as well, the Polar-5 from the Alfred Wegener Institute for Polar and Marine Research.

After taking some photos and enjoying the sunshine my fingers got cold so I headed back onto the plane for a packed lunch.

Aeroplanes!

Three research planes all in a row! From left to right, our plane the 146, the Polar-5 and the BAS MASIN Twin Otter. All on the big coldness that is Svalbard. Photo by Rhiannon Davies.

We took off again and headed East across Svalbard, the views were spectacular and the pilots thanked us for the opportunity to fly there! Then we began to fly over the sea ice we transitioned from thicker ice over very thin translucent sheets to newly formed frazil ice. The pilots brought us to the point allocated for the start of our science and we ‘profiled’ down to our minimum safe altitude over the sea ice. We then flew for half an hour before turning round and taking the plane to a higher altitude and flying back over where we had just been, we did several legs in this manner. This allows us to get a profile of the atmosphere over the ice edge. We found a very stable boundary layer over the ice which became more turbulent at low levels over the sea.The instruments had picked up and interesting aerosol/haze layer which we made sure we flew through.The transition to convective cumulus cloud was a bit further south than the models had predicted, this isn’t all bad though as wouldn’t have a job if forecasts were perfect!

Then we turned for Kiruna and flew back home. We landed as the sun was starting to set at about 6pm. A long day for all!

Sunset

Sunset over Kiruna. Photo by Rhiannon Davies

After a debrief we headed back to our hotels and to the pub for a moose burger!

First Flight

Just a quick one (it’s late and we have another early start tomorrow for flight number 3). Two views from the flight deck on our first flight.

Sea ice from 100ft

Descending to 100ft over sea ice.

 

Sea-smoke

Sea-smoke – condensation forming as cold air moves over warmer water.

ICE-ACCACIA – Extra measurements during ACCACIA

ICE-ACCACIA is a project which will be running alongside the main ACCACIA project. It will collect samples which will be used to investigate the properties of the aerosols with respect to their properties as ice nuclei. From the samples we will be able to quantify the number and efficiency of ice nuclei in the remote Arctic for the first time. The exact chemical composition of these particles is very important when it comes to how good they are at ‘seeding ice crystals’.

This sensitivity of clouds to ice nucleation arises in part because cloud water droplets in the absence of particles which nucleate ice can supercool to about -36oC. In fact very pure water will remain liquid at temperatures well below 0 oC but will freeze instantly when the ‘supercooled’ liquid water comes into contact with dust (checkout this YouTube clip).

Samples collected in Kiruna will be analysed in a laboratory which has been set up in the Arena Arctica hangar. The samples are suspended in tiny cloud droplets, and the temperatures at which they freeze are recorded by taking a video of the droplets as they are cooled.ice_lab

The ICE-ACCACIA project is led by Dr Ben Murray from the Institute for Climate and Atmospheric Science in Leeds, the ICE-ACCACIA team includes Dr Jim McQuaid, Dr Kelly Baustian and Dr Theo Wilson from ICAS. The results are used in atmospheric models which give us a better understanding of the effects of cloud on climate.