Polar 6 campaign NETCARE 2014 Resolute Bay/Nunavut/Canada

Weekly Report 2: 14. July – 24.July 2014 ___________________________________________________________________________ 1. Introduction This report briefly summarizes flight activities during the second part of the campaign. During the third and forth week of the campaign, we concluded a set of flights under clear sky conditions, learning more about the nature of new particle formation and growth both over ice covered and open water conditions of Lancaster Sound and some northern Polynas. Attempts were made to sample at low altitude the atmosphere over both fast ice and melting ice. We were fortunate that Resolute in July was well located for these studies, close to the ice edge. As well, there were opportunities to study low lying clouds that had nucleated on a very small number of particles, leading to clouds with low droplet number density but large size droplets. Vertical profiles to roughly 10000 feet were conducted on each flight. One particularly interesting flight was conducted to the eastern end of Devon Island where, upon descent, we saw clear indication of secondary aerosol formation through the condensation of methane sulfonic acid, i.e. a species that arises from oceanic gaseous emissions. After the weather change (see below), enhanced levels of methane sulfonic acid were repeatedly observed at low altitudes, especially over the open ocean. But the period was also characterized by a period of foggy weather that precluded flying, as we anticipated the arrival of the Amundsen for overlap flights. One of the highlights during the campaign was the measurement of the emission plume of the CCGS Amundsen. Three times - the flights on July 19, 20, and 21 (morning flight) - ship emissions of the Amundsen research ice breaker were measured, with the aim to detect the plume by the different sensors. Most of the plume encounters were observable in NOx, as well as CO2, such that emission indices of emissions (Black Carbon, particle numbers, CCN) can be determined. Also, particle mass spectra were recorded during several plume crossings by the ALABAMA and SP-AMS instruments, allowing for particle composition to be determined. The first emission plume measurements were carried out during the operation of the CCGS Amundsen in the Lancaster Sound (Northwest Passage), ship station 301 (74,18°N, 83,54°W). Measurement

two and three were done after the CCGS Amundsen reached the ice edge and they operated under ice conditions, North of Somerset Island, only less than 50 nm from Resolute Bay. With the engines working harder in the ice, emissions (such as NOx), were noticeably higher. The CCGS Amundsen emission plume studies were support by plume forecasting with the WRF (Weather Research Forecast) Chem. model from LATMOS Paris. 2. Weather Situation The weather situation in the second half of the NETCARE campaign changed substantially from the first half. An upper air low was stationary above the area of interest. Lows in the lower atmosphere moved in from the west and warm air with high humidity streamed in. This warm air produced stable fog over the nearby cold surfaces. An intensive low-pressure system with several centers became stationary and after the fog situation, several frontal cloud bands with precipitation, low ceilings and bad visibilities reached the area. Also the wind picked up from northeast with an average wind speed of 15 to 20 knots and gusts up to 40 knots. 3. Science equipment The instrumentation continued to operate in an excellent manner without any major failures, exceptional the failure of the SP2 instrument during flight fourteen and fifteen. With the input from Aventech Barrie the AIMMS20 data logging was successful realized and the 1 Hz meteorological data were available for the last flights. During the flights the systems of MPIC and JGU Mainz (CO sensor, CO2/H20 sensor and ALABAMA) performed without problems. During all these 5 flights enhanced CO values were observed at higher altitudes (above approx. 3000 feet). Also particle concentrations were elevated and the particles were found to be mainly composed of sulfate and organics. Most likely these air masses are influenced by biomass burning events in the North West Territories, as predicted by MACC forecasts. A comprehensive set of instrument calibrations was conducted, in part taking advantage of the expertise of Environment Canada personnel who were in Resolute Bay for the first half of the campaign. The SP-AMS has been successfully operating throughout the final week of the campaign. The SP-AMS has generally sampled with a time resolution of 20-30 seconds to obtain both averaged particle chemical composition and size-resolved chemical composition. In this mode, the instrument has measured higher levels of methane sulfonic acid at lower levels and generally larger particle sizes in the later part of the campaign. The SP-AMS sampled at 1Hz during the ship emissions measurements and was able to capture some of the plumes. During

these measurements a large amount of organic aerosol was measured as well as some black carbon. As well, the CPC, SMPS and CCNC instruments operated without problem. 4. Flight Summary The scientific flights are listed below. In total, 35.4 hours (flight time) have been flown during the second part of the campaign, including the ferry flights from Resolute Bay back to Muskoka. With the arrival in Muskoka on July 24, 2014 and the beginning of the de-integration the NETCARE campaign ended. Five more research flights were done. • 17th of July 2014: We flew again southwest of Resolute over Lancaster

Sound, then east over the Sound and back to the west at low level. The measurements were initially over solid ice and then over/in low-level cloud.

• 19th of July 2014: First of the emission plume measurements in the Lancaster Sound, nearby Devon Island.

• 20th of July 2014: The second emission measurements were done after the Amundsen reached the ice edge and operated North of Somerset Island.

• 21th of July 2014: During the morning flight we repeated the flight from the day before – measurements of the emission plume, North of Somerset Island, whereby the Amundsen steamed to North in direction of the Wellington channel.

• 21th of July 2014: During the afternoon flight (last survey flight) we measured the aerosol particle nearby the ice edge and flown the in low level during West of Resolute Bay over sea ice covered area.

 No. Flight / Date Subject Flight time Nr. 11 / 17.07.2014 Survey Flight 4.7 Nr. 12 / 19.07.2014 Survey Flight 5.1 Nr. 13 / 20.07.2014 Survey Flight 4.7 Nr. 14 / 21.07.2014 Survey Flight 4.0 Nr. 15 /21.07.2014 Survey Flight 4.0 Nr. 16-17 / 23.07.2014 Resolute Bay - Churchill (Ferry) 6.6 Nr. 18-19 / 23.07.2014 Churchill – Muskoka (Ferry) 6.3 TOTAL 35.4

Table 1: Overview on the flight activity of POLAR 6 The NETCARE Team Resolute Bay, 24. July 2014

Figure 1: Weather chart on July 18, 2014– Resolute Bay is influenced by intensive low-pressure systems (ECMWF data, modified by Ralf Brauner)

Figure 2: Overview of the flight activity (prepared by Christian Conrad)

Figure 3: Low-level clouds near Devon Island (photo: Kevin Elke)

Figure 4: POLAR 6 meets CCGS Amundsen (photo: Maurice Levasseur)