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Larcform 1 - single column model intercomparison of Arctic air formation, link to model results in NetCDF format (2016)

Pithan, Felix ; Ackerman, Andrew ; Angevine, Wayne ; [et al.]

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In: Supplement to: Pithan, Felix; Ackerman, Andrew; Angevine, Wayne; Hartung, Kerstin; Ickes, Luisa; Kelley, Maxwell; Medeiros, Brian P; Sandu, Irina; Steeneveld, Gert-Jan; Sterk, HAM; Svensson, Gunilla; Vaillancourt, Paul A; Zadra, Ayrton (2016): Strengths and biases of models in representing the Arctic winter boundary layer - the Larcform 1 single column model intercomparison. Journal of Advances in Modeling Earth Systems, 8(3), 1345-1357, https://doi.org/10.1002/2016MS000630

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Publication Date: 2023-01-13

Description: Weather and climate models struggle to represent lower tropospheric temperature and moisture profiles and surface fluxes in Arctic winter, not least because they lack or misrepresent physical processes that are specific to high latitudes. The Arctic boundary layer in winter has been observed to be in either a radiatively clear or cloudy state: The radiatively clear state is characterized by strong surface radiative cooling leading to the build-up of surface-based temperature inversions, whereas the cloudy state occurs when cloud liquid water is present in the atmospheric column, allowing little or no surface radiative cooling and leading to weaker and typically elevated temperature inversions. Many large-scale models have been shown to lack the cloudy state, and some do substantially underestimate stability in the clear state. We here present results from the first Lagrangian ARCtic air FORMation experiment (Larcform 1), a GASS (Global atmospheric system studies) single-column model intercomparison which reproduces these biases of large-scale models in an idealised setup.

Type: Dataset

Format: application/zip, 8.9 MBytes

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Classification of Arctic multilayer clouds using radiosonde and radar data in Svalbard (2019)

Vassel, Maiken ; Ickes, Luisa ; Maturilli, Marion ; [et al.]

COPERNICUS GESELLSCHAFT MBH

In: EPIC3Atmospheric Chemistry and Physics, COPERNICUS GESELLSCHAFT MBH, 19, pp. 5111-5126, ISSN: 1680-7316

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Publication Date: 2020-03-05

Description: Multilayer clouds (MLCs) occur more often in theArctic than globally. In this study we present the results of a detection algorithm applied to radiosonde and radar datafrom an 1-year time period in Ny-Ålesund, Svalbard. Multi-layer cloud occurrence is found on 29 % of the investigated days. These multilayer cloud cases are further analysed regarding the possibility of ice crystal seeding, meaning that an ice crystal can survive sublimation in a subsaturated layer between two cloud layers when falling through this layer. For this we analyse profiles of relative humidity with respect to ice to identify super- and subsaturated air layers. Then the sublimation of an ice crystal of an assumed initial size of r=400 μm on its way through the subsaturated layer is calculated. If the ice crystal still exists when reaching a lower supersaturated layer, ice crystal seeding can potentially take place. Seeding cases are found often, in 23 % of the investigated days (100 % includes all days, as well as non-cloudy days). The identification of seeding cases is limited by the radar signal inside the subsaturated layer. Clearly separated multilayer clouds, defined by a clear interstice in the radar image, do not interact through seeding (9 % of the investigated days). There are various deviations between the relative humidity profiles and the radar images, e.g. due to the lack of ice-nucleating particles (INPs) and cloud condensation nuclei (CCN). Additionally, horizontal wind drift of the radiosonde and time restriction when comparing radiosonde and radar data cause further deviations. In order to account for some of these deviations, an evaluation by manual visual inspection is done for the non-seeding cases.

Repository Name: EPIC Alfred Wegener Institut

Type: Article , isiRev

Format: application/pdf

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