Single column models Gunilla Svensson and Frank Kauker Single column models Gunilla Svensson and Frank Kauker* Department of Meteorology Bolin Centre for Climate Research and Swedish e-science Research Centre (SeRC) *Alfred Wegener Institute

What can Single Column Models (SCM) be used for? By extracting a column out of a three-dimensional model, one is able to separate the effects on the local evolution from the large- scale forcing and the local (vertical) processes SCM experiments can be idealized or real (or something in between): Ideal cases and be compared with process resolving models such as LES Real cases, forced by the three-dimensional model, re- analysis or observations, can be compared with observations Sensitivity to parameters, parameterization schemes and their interactions can be done in a controlled environment and can aid parameterization development

What can Single Column Models (SCM) be used for? There is a long tradition in using atmospheric SCM to understand processes, and intercompare parameterizations, many of them have been coordinated within GEWEX Global Atmospheric System Study (GASS) Ocean and sea-ice 1-D models exist but fewer studies are published, and to our knowledge no intercomparison studies have been conducted

Arctic processes Morrison et al., 2011 Persson 2012 April 30 – June 20 Atmosphere Morrison et al., 2011 Snow Sea-ice Ocean Solomon et al., 2015 Persson 2012

Airmass transformation Transport in over sea ice in winter opaquely cloudy Radiatively clear case Open ocean Sea ice Pithan et al., 2013

Polar airmass transition – Larcform1 GASS SCM model intercomparison Pithan et al., 2016

Surface response of synoptic events SHEBA winter z Model development should be done in the whole column. Observations need to support that. Snow Ice Ocean Persson et al. 2016

AOSCM experimental setup Eulerian or Lagrangian Nudging or dynamical tendencies Current system EC-Earth: OpenIFS cycle 40r1 OASIS3-MCT LIM3 NEMO3.6 Nudging or dynamical tendencies

An extreme warm advection episode during ACSE 1 – 7 Tjernström et al. 2015

AOSCM L137 Simulation of ACSE case LES case z0=0.006m SCM for LES case LWC (g kg-1) LES - MIMICA LES case z0=0.006m SCM – LES SCM for LES case AOSCM – LES AOSCM for LES case AOSCM z0=0.001 Default z0 LES case SCM No moisture advection Sensitivity to advection of moisture and heat SCM No temperature advection

Summer (JJA) averaged surface albedo (1982 -2005) Koenigk et al., 2014

CMIP5 models Atlantic layer inflow to Arctic Biases are likely related to flow/topography interaction and representation of subgrid processes (vertical mixing) Ilicak et al., 2016

CMIP5 models Mean March mixed-layer depth Ilicak et al., 2016

1. Introduction Modelled snow volume dramatically different (even when forced with the same Atmospheric reanalysis (ERAinterim))

Atmosphere Ocean Single Column Model (AOSCM) Observations IAOOS and MOSAiC http://www.mosaic-expedition.org

SCM plans Workshop (APPLICATE-YOPP-GASS) last week in Stockholm on airmass transformation – outcome include recommendations for a second more realistic airmass transformation intermodel comparison experiment, Larcform 2 Existing observations will be used to design more intercomparioson cases focusing on different seasons/processes, also suitable for LES and/or AOSCM intercomparison (funded by Applicate) Proposed that AOSCM will be run for the observational site in forecast mode during MOSAiC – concept will be tested next year during the ODEN expedition

1-D modeling in MOSAIC