Laki Study

Model-run description for several simulations with NorESM-M)

Purpose of simulation: Understand climate effects of large volcanic eruptions in Northern hemisphere.

Contact person: Alf Grini (alf.grini@met.no)

Data owner: Alf Grini (alf.grini@met.no)

Revision Number: r196

Production computer used: Cray XT3 in Bergen (hexagon)

Production date: Sprint 2014

Ensemble runs: Yes, 20 members

Storage locations: NorStore (/projects/NS2345K/noresm/cases/KatlaStudy), where BF2_VolcanoStart.. is ensemble members with volcano. NoVolcano.. are ensemble members for no eruption ensemble members.

Storage space: 1,6 Tb at NorStore (for each ensemble member)

Projects: PEGASOS

Publications: None (yet)

Papers in preparation:

Simulation name(s): N20TRAERCN_f19_g16_0X), where X = ensemble member, where X = 1,2,3 for this set-up

Compset name used: N20TRAERCN

Model type: Fully coupled

Type of run: Hybrid/branch

Simulation period: Each ensemble member is 4-5 years

Initialisation Start from CMIP5 transient simulation, N20TRAERCN_f19_g16_06

Resolution: f19_g16= 1.9×2.5 degree atmosphere/land. Dipolar ocean/ice grid, ~ 1 degree

Emission year(s): 1850-2005 (aerosol and aerosol-precursors)

Greenhouse gases: Prescribed concentrations 1850-2005

Emission inventories IPCC AR5, see references in Kirkevåg et al. (2013)

Frequency for output: Monthly and selected daily 1850-1949: Monthly + daily + 6h +3h as defined by CMIP5: 1950-2005

Active/changing forcing agents: Greenhouse gases: Direct and indirect (1. & 2.) effects of SO4, POM and BC.

Special considerations: An extension to the normal NorESM-M has been created. In the extended version it is possible to specify a vulcanic eruption at some lon/lat location and some height distribution. The volcano can then have several eruptions distributed in time. This is used to simulate the Laki eruption on Iceland 1783.

Tuning parameters which are changed relative to the host model CAM4:

rhminl: 0.90 lower RH threshold for formation of low stratiform clouds (0.91 in CAM4)

critrp: 5.0 mm/day maximum prcipitation rate for suppression of autoconversion of cloud water (0.5 mm/day in CAM4)

r3lc: 14 um critical mean droplet volume radius for onset of autoconversion (10 um in CAM4)