Observations within (AC)³
Data will be collected during dedicated, short–term field campaigns using ground stations, ship, balloon, and aircraft, and intensive, long–term observations from the ground (at super sites) and satellites for the circum Arctic region. The temporary, intensive field campaigns will be performed in different seasons to cover various cloud, aerosol, sea ice, and meteorological situations. They aim at detailed process studies with a focus on atmospheric and surface properties and feedback mechanisms driving Arctic amplification. The long–term observations target on trends and spatio–temporal variability during longer time periods (up to the last 3.5 decades). The short–term intensive campaigns are embedded in the long–term data sampling. Different temporal and spatial scales will be covered by using diverse observational platforms. The collected data will have some overlap and complementarity, which assures coherence.
Overview of (AC)³ campaigns
Arctic amplification might cause a weaker jet stream, which would result in an increase of undulations (wavier jet), an amplification of Rossby wave amplitudes, and more blocking situations. These dynamic consequences would promote warm/moist air intrusions and continental cold air outbreaks, which would further amplify the Arctic warming (positive feedback).
We have observed the transformations of air mass properties along their pathways over open water, the MIZ, and the sea ice of the Arctic Ocean using HALO to follow the air masses in a quasi-Lagrangian way.
Eventually we have achieved an exciting and impressive data set to explore the phenomena we are interested in:
- Warm/Moist Air Intrusions
- Atmospheric Rivers
- Cold Air Outbreaks (CAOs)
- Air Mass Tracking — Weak CAOs
- Polar Low
- Arctic Cirrus over Sea Ice
Each of the two Polar aircraft flew more than 100 hours during 13 flight missions. HALO collected data during almost 150 flight hours, dropped 347 sondes and completed a flight distance of 113,000 km during 17 research flights. And there were almost no failures of the instrumentation! Our three aircraft performed 8 closely collocated flight mission, in addition to flights jointly carried out with the British FAAM and the French SAFIRE.
September 2019 – September 2020
During the MOSAiC expedition the German ice breaker Research Vessel (RV) Polarstern (central observatory), will be frozen in the Siberian sea ice in fall 2019 along with a distributed network of research sites on the ice. This observational constellation will move across the Arctic ice cap with the natural transpolar drift of the sea ice for a full year. As a result of the observations, shortcomings in the numerical description of Arctic processes and sources of erroneous forecasts in the Arctic will be identified.
(AC)³ is a major German player within the international MOSAiC consortium in which 17 nations are involved. (AC)³ will lead two of the planned airborne campaigns (MOSAiC-Airborne observations in the Central Arctic, MOSAiC-ACA) using the Polar 5 and Polar 6 aircraft of AWI to complement the observations on RV Polarstern.
AFLUX is a joint project of different German universities and research institutes and of one French university. The general goal of AFLUX is to obtain a comprehensive data set of atmospheric parameters in the polar cloud-covered and cloud-free atmospheric boundary layer (ABL) over sea ice. The combined analysis of the measurement data and of suitable modeling results will be used to estimate the role of Arctic clouds and of surface heterogeneities for the amplified climate change in polar regions.
The research flights aim to measure turbulent and radiative fluxes of energy and depending on the properties of low-level clouds and aerosol particles, as well as on trace gas concentration. To that aim both in situ measurement techniques and remote sensing instruments will be applied.
The general goal of PAMARCMiP is to obtain a comprehensive data set of atmospheric and sea ice properties that will be used to understand and quantify the interaction between atmospheric aerosol, surface optical properties, and clouds in the central Arctic.
PAMARCMiP combines ground-based stationary and mobile measurements at and in vicinity of the Villum Research Station (Greenland), airborne measurements by the Polar 5 research aircraft, and profiling the atmosphere by tethered-balloon observations.
The general goal of ACLOUD is to obtain a comprehensive data set of a diversity of atmospheric parameters that will be used to understand and quantify specific physical processes in, above, and below Arctic clouds. The analysis of the measurement data will, in combination with different kinds of atmospheric models, be used to estimate the role of Arctic clouds for the amplified climate change in Polar Regions.
The research flights aim to measure properties of cloud and aerosol particles, trace gas concentration, the energy fluxes in the atmospheric column including radiative fluxes as well as fluxes of sensible and turbulent latent heat. In situ measurement techniques and remote sensing instruments will be applied.
To investigate relevant small-scale processes in detail, an intensive field campaign was conducted during early summer in the central Arctic during the Physical feedbacks of Arctic planetary boundary layer, Sea ice, Cloudand AerosoL (PASCAL) drifting ice floe station. During PASCAL, an ice floe camp was built, while Polarstern was moored to the drifting ice floe. A multitude of physical, meteorological and biological research observations were conducted and is associated with the concurrent aircraft campaign ACLOUD.
The new BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) tethered balloon system combines a set of instruments to measure turbulent and radiative parameters and energy fluxes and has proven its robust performance in cloudy conditions of the Arctic atmospheric boundary layer.
CONCORD 2016 – present
Continuous measurements (ground–based) will be conducted at the German/French research site (AWIPEV) in Ny–Ålesund (Svalbard) throughout the entire duration of (AC)³ within ‘Continuous characterization of the Ny-Ålesund column and radiative effects from ground-based remote sensing’ (CONCORD). The overarching goal of CONCORD is to characterize the thermodynamic structure, clouds, aerosols, trace gases and radiative effects in the atmospheric column on a long–term basis exploiting the synergy of various remote sensing instruments. The analysis will be based on the established routine observations at the research station; new instrumentation will be installed within (AC)³, which will turn Ny–Ålesund into a complete atmospheric supersite providing also vertical cloud information. The long–term column characteristics at Ny–Ålesund and its variability will be connected to the large–scale and local meteorology, and the representativeness will be assessed. Data from other stations (Eureka in Canada, Summit in Greenland, Barrow in Alaska) will be involved.
Satellite observations 2016 – present
Satellite-based measurements play an essential role in bridging temporal and spatial scales. By now, long (more than 30 years) time series of satellite radiance measurements exist. However, these time series consist of inhomogeneous measurements by different instruments and satellites with partly inhomogeneous orbits. Therefore, the generation of homogeneous climate data records of basic measurements
(radiances, reflectivities, brightness temperatures) is rather demanding.
We will use data from passive microwave imagers, which provide daily year-round sea ice information since 1978 (area, drift, type and more). In the solar spectral range, a fleet of satellite instruments provide spectrally and radiometrically calibrated data, which are used for satellite products of surface spectral relectance, albedo, melt ponds, atmospheric constituents (trace gases, clouds, aerosols), and ocean colour. Active space-borne lidar and radar measurements provide supportive information on vertical aerosol, cloud, and precipitation distribution despite their significant limitations with respect to spatial coverage.
Key characteristics of the satellite instruments relevent to (AC)³ and their role in the projects are provided here.