07 Oct 2022
07 Oct 2022
Status: this preprint is currently under review for the journal ACP.

Effects of variable, ice-ocean surface properties and air mass transformation on the Arctic radiative energy budget

Manfred Wendisch1, Johannes Stapf1, Sebastian Becker1, André Ehrlich1, Evelyn Jäkel1, Marcus Klingebiel1, Christof Lüpkes2, Michael Schäfer1, and Matthew D. Shupe3,4 Manfred Wendisch et al.
  • 1Leipzig Institute for Meteorology (LIM), Leipzig University, Germany
  • 2Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 3Physical Sciences Laboratory (PSL), National Oceanic and Atmospheric Administration (NOAA), Boulder, Colorado, USA
  • 4Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, USA

Abstract. Low-level airborne observations of the Arctic surface radiative energy budget are discussed. We focus on the terrestrial part of the budget, quantified by the thermal-infrared net irradiance (TNI). The data have been collected in cloudy and cloud-free conditions over and in the vicinity of the marginal sea ice zone (MIZ) close to Svalbard during two aircraft campaigns in spring of 2019 and in early summer of 2017. The measurements, complemented by ground-based observations available from the literature and radiative transfer simulations, are used to evaluate the influence of surface type (sea ice, open ocean, MIZ), seasonal characteristics, and synoptically driven meridional air mass transports into and out of the Arctic on the near-surface TNI. The analysis reveals a typical four-mode structure of the frequency distribution of the TNI as a function of surface albedo, sea ice fraction, and surface brightness temperature. Two modes prevail over sea ice and another two over open ocean, each representing cloud-free and cloudy radiative states. Characteristic shifts and modifications of the TNI modes during the transition from winter towards early spring and summer conditions are discussed. Furthermore, the influence of warm air intrusions (WAIs) and marine cold air outbreaks (MCAOs) on the near-surface downward thermal-infrared irradiances and the TNI is highlighted for several case studies. It is concluded that during WAIs the surface warming depends on cloud properties and evolution. Lifted clouds embedded in warmer air masses over a colder sea ice surface, decoupled from the ground by a surface-based temperature inversion, have the potential to warm the surface more strongly than near-surface fog or thin low-level boundary layer clouds, because of a higher cloud base temperature. For MCAOs it is found that the thermodynamic profile of the southward moving air mass adapts only slowly to the warmer ocean surface.

Manfred Wendisch et al.

Status: open (until 24 Dec 2022)

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Manfred Wendisch et al.

Manfred Wendisch et al.


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Short summary
Atmospheric radiation measurements have been conducted during two field campaigns using research aircraft. The data are analysed to see if the near-surface air in the Arctic is warmed or cooled if warm/humid air masses from the South enter the Arctic, or cold/dry air moves from the North from the Arctic to mid-latitude areas. It is important to studie these processes and to check if climate models represent them well. Otherwise it is not possible to reliably forecast the furure Arctic climate.