Abstract
Abstract. The two concerted field campaigns, Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) and the Physical feedbacks of Arctic planetary boundary level Sea ice, Cloud and AerosoL (PASCAL), took place near Svalbard from 23 May to 26 June 2017. They were focused on studying Arctic mixed-phase clouds and involved observations from two airplanes (ACLOUD), an icebreaker (PASCAL) and a tethered balloon, as well as ground-based stations. Here, we present the synoptic development during the 35-day period of the campaigns, using near-surface and upper-air meteorological observations, as well as operational satellite, analysis, and reanalysis data. Over the campaign period, short-term synoptic variability was substantial, dominating over the seasonal cycle. During the first campaign week, cold and dry Arctic air from the north persisted, with a distinct but seasonally unusual cold air outbreak. Cloudy conditions with mostly low-level clouds prevailed. The subsequent 2 weeks were characterized by warm and moist maritime air from the south and east, which included two events of warm air advection. These synoptical disturbances caused lower cloud cover fractions and higher-reaching cloud systems. In the final 2 weeks, adiabatically warmed air from the west dominated, with cloud properties strongly varying within the range of the two other periods. Results presented here provide synoptic information needed to analyze and interpret data of upcoming studies from ACLOUD/PASCAL, while also offering unprecedented measurements in a sparsely observed region.
Highlights
The phenomenon of Arctic amplification – the 2–3 times higher warming of the Arctic relative to the global atmosphere – is a major indication of current drastic Arctic climate changes (Serreze and Barry, 2011)
This paper provides an overview of the synoptic development during the ACLOUD airborne and PASCAL ship-based field campaigns, which took place near Svalbard from 23 May to 26 June 2017
Relative to the long-term averages, we identified three key periods representative of the distinct synoptic states during the ACLOUD/PASCAL measurement period: (1) a cold period (CP; 23–29 May; 7 days), (2) a warm period (WP; 30 May–12 June; 14 days), and (3) a normal period (NP; 13–26 June; 14 days)
Summary
The phenomenon of Arctic amplification – the 2–3 times higher warming of the Arctic relative to the global atmosphere – is a major indication of current drastic Arctic climate changes (Serreze and Barry, 2011). Most of these previous observational campaigns in the Arctic obtained relatively few process-level observations of the coupled Arctic climate system, especially related to interactions between clouds and the ABL and with regards to the radiative interaction of the cloud properties with the surface All these campaigns have been conducted in the last decade and measured the “new Arctic” (Jeffries et al, 2013, and references therein), they are hard to compare due to the different synoptic and sea ice conditions as well as climate regimes in the various regions. Following an introduction of the ACLOUD/PASCAL set-up in Sect. 2.1, Sect. 2.2, 2.3, and 2.4 describe the surface-based measurements, satellites and models applied, respectively
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