Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-1135
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
19 Jan 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
The Microphysics of Clouds over the Antarctic Peninsula – Part 2: modelling aspects within Polar WRF
Constantino Listowski and Tom Lachlan-Cope British Antarctic Survey, NERC, High Cross, Madingley Rd, Cambridge, CB3 0ET, UK
Abstract. The first intercomparisons of cloud microphysics schemes implemented in the Weather Research and Forecasting (WRF) mesoscale atmospheric model (version 3.5.1) are performed in the Antarctic Peninsula using the polar version of WRF (Polar WRF) at 5 km resolution, along with comparisons to the British Antarctic Survey's aircraft measurements (presented in Part 1 of this work, Lachlan-Cope et al., 2016). This study follows previous works suggesting the misrepresentation of the cloud thermodynamic phase in order to explain large radiative biases derived at the surface in Polar WRF continent-wide, and in the Polar WRF-based operational forecast model Antarctic Mesoscale Prediction System (AMPS) over the Larsen C Ice shelf. Several cloud microphysics schemes are investigated: the WRF Single-Moment 5-class scheme (WSM5), the WRF Double-Moment 6-class scheme (WDM6), the Morrison double-moment scheme, the Thompson scheme, and the Milbrandt- Yau Double-Moment 7-class scheme. WSM5 used in AMPS struggles the most to capture the observed supercooled liquid phase mainly because of their ice nuclei parameterisation overestimating the number of activated crystals, while other micro- physics schemes (but not WSM5's upgraded version, WDM6) manage much better to do so. The best performing scheme is the Morrison scheme for its better average prediction of occurrences of clouds, and cloud phase, as well as its lowest surface radiative bias over the Larsen C ice shelf in the infrared. This is important for surface energy budget consideration with Polar WRF since the cloud radiative effect is more pronounced in the infrared over icy surfaces. However, our investigation shows that all the schemes fail at simulating the supercooled liquid mass at some temperatures (altitudes) where observations show evidence of its persistence. An ice nuclei parameterisation relying on both temperature and aerosol content like DeMott et al. (2010) (not currently used in WRF cloud schemes) is in best agreement with the observations, at temperatures and aerosol concentration characteristic of the Antarctic Peninsula where the primary ice production occurs (Part 1), compared to parame- terisation only relying on the atmospheric temperature (used by the WRF cloud schemes). Overall, a realistic ice microphysics implementation is paramount to the correct representation of the supercooled liquid phase in Antarctic clouds.

Citation: Listowski, C. and Lachlan-Cope, T.: The Microphysics of Clouds over the Antarctic Peninsula – Part 2: modelling aspects within Polar WRF, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1135, in review, 2017.
Constantino Listowski and Tom Lachlan-Cope
Constantino Listowski and Tom Lachlan-Cope
Constantino Listowski and Tom Lachlan-Cope

Viewed

Total article views: 246 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
175 56 15 246 3 15

Views and downloads (calculated since 19 Jan 2017)

Cumulative views and downloads (calculated since 19 Jan 2017)

Viewed (geographical distribution)

Total article views: 246 (including HTML, PDF, and XML)

Thereof 244 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 29 Mar 2017
Publications Copernicus
Download
Short summary
Modelling Antarctic tropospheric clouds remains challenging because of the lack of observations in this remote place. We use aircraft in-situ observations to assess the performances of cloud simulations over the Antarctic Peninsula within the Polar Weather Research and Forecasting model. The cloud scheme used by the operational forecast model AMPS has the poorest performance. Ice microphysics is key for correctly modelling the supercooled liquid phase, and for lowering the radiation biases.
Modelling Antarctic tropospheric clouds remains challenging because of the lack of observations...
Share