Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017

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.

Local and Remote Controls on Arctic Mixed‐Layer Evolution

“…The ice and cloud situation on 6 June 2017 is shown in Figure . As described by Knudsen et al () and Wendisch et al (), on these days surface pressure was relatively high in the area, and low clouds were predominantly single layer and in mixed phase. The low‐level flow was initially from the southwest, bringing relatively warm and moist air masses into the area.…”

Low-level mixed-phase clouds in a complex Arctic environment

“…Large-scale advection and air mass properties are known to influence MPC properties (Mioche et al, 2017;Qiu et al, 2018, amongst others). Previous studies suggest that at Svalbard northerly flow is often associated with cold air masses originating from the central Arctic and that southerly flows bring warmer and more humid air from lower latitudes (Dahlke and Maturilli, 2017;Knudsen et al, 2018;Kim et al, 2017;Mioche et al, 2017). Furthermore, the open sea west of the Svalbard archipelago might act as a local source of humidity and heat.…”

“…Particularly low-level mixed-phase clouds are important for the warming of near-surface air (Shupe and Intrieri, 2004;Intrieri et al, 2002;Zuidema et al, 2005). The multitude of microphysical and dynamical processes within the cloud and the interactions with local and large-scale processes make these mixed-phase clouds difficult to represent in numerical models (Morrison et al, 2008(Morrison et al, , 2012Komurcu et al, 2014). Improvements in the process-level understanding are still required to improve the description of low-level mixed-phase clouds in climate models (McCoy et al, 2016;Kay et al, 2016;Klein et al, 2009).…”

On the Thermodynamic Preconditioning of Arctic Air Masses and the Role of Tropopause Polar Vortices for Cold Air Outbreaks From Fram Strait

“…Such air masses feature the typical characteristics of marine CAOs, namely, upward fluxes of sensible heat, the uptake of moisture, and convective overturning with cloud formation and the associated release of latent heat (e.g., Brümmer, 1997;Papritz & Sodemann, 2018;Papritz et al, 2015;Renfrew & Moore, 1999). This definition of CAOs has-sometimes with slight variations-been employed in a number of previous studies of CAOs in this region (e.g., Bracegirdle & Gray, 2008;Knudsen et al, 2018;Kolstad & Bracegirdle, 2008;Kolstad et al, 2009;Papritz & Sodemann, 2018;Papritz & Spengler, 2017).…”