======  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:**        Spring 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= 1.9x2.5 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 [[http://www.geosci-model-dev.net/6/207/2013/gmd-6-207-2013.html|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)