Aerosol impacts on the entrainment efficiency of Arctic mixed-phase convection in a simulated air mass over open water

Abstract. Springtime Arctic mixed-phase convection over open water in the Fram Strait as observed during the recent ACLOUD (Arctic CLoud Observations Using airborne measurements during polar Day) field campaign is simulated at turbulence-resolving resolutions. The first objective is to assess the skill of large-eddy simulation (LES) in reproducing the observed mixed-phase convection. The second goal is to then use the model to investigate how aerosol modulates the way in which turbulent mixing and clouds transform the low-level air mass. The focus lies on the low-level thermal structure and lapse rate, the heating efficiency of turbulent entrainment, and the low-level energy budget. A composite case is constructed based on data collected by two research aircraft on 18 June 2017. Simulations are evaluated against independent datasets, showing that the observed thermodynamic, cloudy, and turbulent states are well reproduced. Sensitivity tests on cloud condensation nuclei (CCN) concentration are then performed, covering a broad range between pristine polar and polluted continental values. We find a significant response in the resolved mixed-phase convection, which is in line with previous LES studies. An increased CCN substantially enhances the depth of convection and liquid cloud amount, accompanied by reduced surface precipitation. Initializing with the in situ CCN data yields the best agreement with the cloud and turbulence observations, a result that prioritizes its measurement during field campaigns for supporting high-resolution modeling efforts. A deeper analysis reveals that CCN significantly increases the efficiency of radiatively driven entrainment in warming the boundary layer. The marked strengthening of the thermal inversion plays a key role in this effect. The low-level heat budget shifts from surface driven to radiatively driven. This response is accompanied by a substantial reduction in the surface energy budget, featuring a weakened flow of solar radiation into the ocean. Results are interpreted in the context of air–sea interactions, air mass transformations, and climate feedbacks at high latitudes.

[1]  Yang Yang,et al.  Anthropogenic Aerosols Effects on Ice Clouds: A Review , 2022, Atmosphere.

[2]  T. L’Ecuyer,et al.  Global evidence of aerosol-induced invigoration in marine cumulus clouds , 2021, Atmospheric Chemistry and Physics.

[3]  A. Nenes,et al.  Secondary ice production processes in wintertime alpine mixed-phase clouds , 2021, Atmospheric Chemistry and Physics.

[4]  M. Wendisch,et al.  Case study of a humidity layer above Arctic stratocumulus and potential turbulent coupling with the cloud top , 2021 .

[5]  G. Faluvegi,et al.  Present and future aerosol impacts on Arctic climate change in the GISS-E2.1 Earth system model , 2021, Atmospheric Chemistry and Physics.

[6]  M. Wendisch,et al.  Employing airborne radiation and cloud microphysics observations to improve cloud representation in ICON at kilometer-scale resolution in the Arctic , 2020, Atmospheric Chemistry and Physics.

[7]  J. Quaas,et al.  CO2-forced changes of Arctic temperature lapse rates in CMIP5 models , 2020 .

[8]  E. Jäkel,et al.  Small-scale structure of thermodynamic phase in Arctic mixed-phase clouds observed by airborne remote sensing during a cold air outbreak and a warm air advection event , 2019, Atmospheric Chemistry and Physics.

[9]  M. Wendisch,et al.  Meteorological conditions during the ACLOUD/PASCAL field campaign near Svalbard in early summer 2017 , 2018, Atmospheric Chemistry and Physics.

[10]  Manfred Wendisch,et al.  Role of air-mass transformations in exchange between the Arctic and mid-latitudes , 2018, Nature Geoscience.

[11]  J. Hartmann,et al.  New calibration procedures for airborne turbulence measurements and accuracy of the methane fluxes during the AirMeth campaigns , 2018, Atmospheric Measurement Techniques.

[12]  U. Lohmann,et al.  A model intercomparison of CCN-limited tenuous clouds in the high Arctic , 2017, Atmospheric Chemistry and Physics.

[13]  Robert M. Graham,et al.  Extreme cyclone events in the Arctic: Wintertime variability and trends , 2017 .

[14]  Christine Wesche,et al.  Polar aircraft Polar5 and Polar6 operated by the Alfred Wegener Institute , 2016 .

[15]  E. Barnes,et al.  The impact of Arctic warming on the midlatitude jet‐stream: Can it? Has it? Will it? , 2015 .

[16]  G. Mann,et al.  The complex response of Arctic aerosol to sea-ice retreat , 2014 .

[17]  T. Mauritsen,et al.  Arctic amplification dominated by temperature feedbacks in contemporary climate models , 2014 .

[18]  A. P. Siebesma,et al.  The GASS/EUCLIPSE model intercomparison of the stratocumulus transition as observed during ASTEX: LES results , 2013 .

[19]  K. Steffen,et al.  July 2012 Greenland melt extent enhanced by low-level liquid clouds , 2013, Nature.

[20]  Thorsten Mauritsen,et al.  Meteorological conditions in the central Arctic summer during the Arctic Summer Cloud Ocean Study (ASCOS) , 2012 .

[21]  M. Shupe,et al.  An Arctic CCN-limited cloud-aerosol regime , 2011 .

[22]  A. P. Siebesma,et al.  Formulation of the Dutch Atmospheric Large-Eddy Simulation (DALES) and overview of its applications , 2010 .

[23]  P. Novelli,et al.  Assessing the relative contributions of transport efficiency and scavenging to seasonal variability in Arctic aerosol , 2010 .

[24]  C. Ritter,et al.  AMALi - the Airborne Mobile Aerosol Lidar for Arctic research , 2009 .

[25]  Sungsu Park,et al.  Intercomparison of model simulations of mixed‐phase clouds observed during the ARM Mixed‐Phase Arctic Cloud Experiment. I: single‐layer cloud , 2009 .

[26]  Yong Cai,et al.  Performance characteristics of the ultra high sensitivity aerosol spectrometer for particles between 55 and 800 nm: Laboratory and field studies , 2008 .

[27]  V. Masson,et al.  How important is the vertical structure for the representation of aerosol impacts on the diurnal cycle of marine stratocumulus , 2008 .

[28]  Audrey B. Wolf,et al.  Intercomparison of model simulations of mixed‐phase clouds observed during the ARM Mixed‐Phase Arctic Cloud Experiment. II: Multilayer cloud , 2008 .

[29]  K. D. Beheng,et al.  A two-moment cloud microphysics parameterization for mixed-phase clouds. Part 1: Model description , 2006 .

[30]  K. D. Beheng,et al.  A two-moment cloud microphysics parameterization for mixed-phase clouds. Part 2: Maritime vs. continental deep convective storms , 2006 .

[31]  Martin Köhler,et al.  Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case , 2004 .

[32]  P. Field,et al.  Ice nucleation characteristics of an isolated wave cloud , 2002 .

[33]  R. Rasmussen,et al.  Explicit forecasting of supercooled liquid water in winter storms using the MM5 mesoscale model , 1998 .

[34]  E. Bigg,et al.  Sudden changes in arctic atmospheric aerosol concentrations during summer and autumn , 1996 .

[35]  T. Choularton,et al.  The Effect of Rimer Surface-Temperature on Ice Splinter Production by the Hallett-Mossop Process , 1986 .

[36]  S. Nicholls.  The dynamics of stratocumulus: Aircraft observations and comparisons with a mixed layer model , 1984 .

[37]  J. Klett,et al.  Microphysics of Clouds and Precipitation , 1978, Nature.

[38]  J. Hallett,et al.  Production of secondary ice particles during the riming process , 1974, Nature.

[39]  E. Bigg.  The formation of atmospheric ice crystals by the freezing of droplets , 1953 .

[40]  K. Markowicz,et al.  Simulation of long-term direct aerosol radiative forcing over the arctic within the framework of the iAREA project , 2021 .

[41]  P. Kollias,et al.  Microwave Radar/radiometer for Arctic Clouds MiRAC: First insights from the ACLOUD campaign , 2019 .

[42]  M. Shupe,et al.  Resilience of persistent Arctic mixed-phase clouds , 2012 .

[43]  Dimitar Ouzounov,et al.  Terra and Aqua MODIS products available from NASA GES DAAC , 2004 .