1. 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

2. 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

3. 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

4. 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

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

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

7. 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

8. 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

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

10. 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

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

12. 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

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

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

15. Atmosphere Ocean Single Column Model (AOSCM)
Observations IAOOS and MOSAiC

16. 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

17. 1-D modeling in MOSAIC