======  N_r99PDX  ======

===== Model-run description for three simulations with NorESM1-M =====

**Purpose of simulation:**  Estimate the effect of BC on global and Arctic climate

**Contact person:**         Alf Kirkevåg (alf.kirkevag@met.no)

**Data owner:**             Alf Kirkevåg (alf.kirkevag@met.no) 

**Revision Number:**        r99  

**Production computer used:** Cray XT in Bergen (hexagon)

**Production date:**        October - November 2010 

**Storage locations:**      NorStore (/norstore_osl/projects/NS2345K/noresm/cases/N_r99PDX), where X = yr116, noBCyr116, noBCdepyr116  

**Storage space:**          1500 Gb at NorStore 

**Projects:**               EarthClim/ACCESS

**Publications:**            

**Papers in preparation:**  Sand et al. (submitted)

**Simulation name(s):**     N_r99PDX, where X = yr116, noBCyr116, noBCdepyr116 
 
**Compset name used:**      NAER2000

**Model type:**             Fully coupled

**Type of run:**            Initial

**Simulation period:**      92 years

**Spin-up period:**         116 years 

**Initialisation:**         

**Ensemble runs:**          No    

**Resolution:**             f19_g19 = 1.8x2.5

**Emission year(s):**       2000 (aerosols and precursors), but BC emissions set to 0 for X = noBCyr116. For X = noBCdepyr116 BC emissions are for year 2000, but deposition of BC on snow and sea-ice is set to 0.      

**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)]]

**Greenhouse gases:**       Prescribed concentrations (2000?) 

**Frequency for output:**   Monthly (for atm, ocn and lnd)

**Active/changing forcing agents:**  Direct and indirect (1. & 2.) effects by anthropogenic SO4, POM and BC. The effects of all BC is found from the difference between the experiments N_r99yr116 and N_r99noBCyr116, and the effect of BC deposited on snow and sea-ice is found from the difference between N_r99yr116 and N_r99noBCdepyr116.

**Special considerations:** 

**Tuning parameters which are changed relative to the host model CCSM4:** 

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) 

R_snw:   500 um      grain size of cold snow overlaying sea-ice (250 um in CICE4)