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aerocom:indirect [2013-10-02 23:07:53]
steve.ghan@pnnl.gov |
aerocom:indirect [2014-01-16 18:23:13]
steve.ghan@pnnl.gov |
| * fix_1850: as in fix_2000, but for pre-industrial emissions \\ | * fix_1850: as in fix_2000, but for pre-industrial emissions \\ |
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| | == Motivation == |
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| | The proposed study is designed to address two key areas of uncertainty: 1) the sensitivity of cloud liquid water path to aerosol, and 2) the competition between heterogeneous and homogeneous nucleation of ice crystals. |
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| | To address issue 1), we’ve added daily and monthly diagnostics that can be compared with CloudSat and MODIS retrievals of the relationship between the aerosol optical depth and the probability of precipitation (Wang et al., 2012). |
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| | To address issue 2), we’ve added experiments in which heterogeneous nucleation is neglected for T%%<%%-37C, and in which ice nucleation for T%%<%%-37C is a prescribed function of temperature (Cooper, 1986). |
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| | We also have added a requirement to nudge toward analyzed winds, which we’ve found greatly reduces the noise due to natural variability without significantly inhibiting the cloud response to the aerosol. (Kooperman et al., 2012). Simulations of six years duration each should be sufficient for all experiments. |
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| | To facilitate analysis and comparison before the 2013 AeroCom meeting, the results should be submitted to the AeroCom repository by August 1, 2013. Please contact steve.ghan@pnnl.gov and xiaohong.liu@pnnl.gov when your results have been submitted. |
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| | Cooper, W. A.: Ice initiation in natural clouds. precipitation enhancement – a scientific challenge, Meteor. Mon., 43, 29–32, 1986. |
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| | Kooperman, G. J., M. S. Pritchard, S. J. Ghan, R. C. J. Sommerville, and L. M. Russell, 2012: Constraining the influence of natural variability to improve estimates of global aerosol indirect effects in a nudged version of the Community Atmosphere Model 5. J. Geophys. Res., 117, doi:10.1029/2012JD018588. |
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| | Wang, M., S. Ghan, X. Liu, T. L’Ecuyer, K. Zhang, H. Morrison, M. Ovchinnikov, R. Easter, R. Marchand, D. Chand, Y. Qian, and J. E. Penner, 2012: Strong constraints on cloud lifetime effects of aerosol using satellite observations. Geophys. Res. Lett., 39, 15, doi:10.1029/2012GL052204. |
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| <ExperimentName> = all_2000, all_1850, hom_2000, hom_1850, fix_2000, or fix_1850 | <ExperimentName> = all_2000, all_1850, hom_2000, hom_1850, fix_2000, or fix_1850 |
| <VariableName> see list below | <VariableName> see list below |
| <VerticalCoordinateType> => "Surface", "Column", "ModelLevel" | <VerticalCoordinateType> => "Surface", "TOA", "Column", "ModelLevel" |
| <Period> => "2008", "2010", ... | <Period> => "2008", "2010", ... |
| <Frequency> => "timeinvariant","hourly", ,"3hourly", "daily", "monthly" | <Frequency> => "timeinvariant","hourly", ,"3hourly", "daily", "monthly" |
| (1) 2D diagnostics for evaluation with satellite data | (1) 2D diagnostics for evaluation with satellite data |
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| 5 years (years 2006-2010) of 3-hourly data from the PD run | 5 years (years 2006-2010) of 3-hourly instantaneous data from the PD run |
| ====== | ====== |
| ^ name ^ long_name (CF if possible) ^ units ^ description ^ | ^ name ^ long_name (CF if possible) ^ units ^ description ^ |
| | z | altitude | m | each layer | | | z | altitude | m | each layer | |
| | airmass | atmosphere_mass_content_of_air | kg m-2 | each layer | | | airmass | atmosphere_mass_content_of_air | kg m-2 | each layer | |
| | mmrdu | mass_fraction_ of_dust_dry_aerosol_in_air | kg/kg | | |
| | mmrbc | mass_fraction_ of_black_carbon_dry_aerosol_in_air | kg/kg | | |
| | mmrso4 | mass_fraction_ of_sulfate_dry_aerosol_in_air | kg/kg | | |
| | cirrus_nso4 | sulfate_aerosol_number_for_homogeneous | m-3 | | |
| | cirrus_ndust | dust_aerosol_number_for_homogeneous | m-3 | | |
| | cirrus_bc | bc_aerosol_number_for_homogeneous | m-3 | | |
| | ccn0.1 | cloud_condensation_nuclei_0.1 | m-3 | each layer (S=0.1%) | | | ccn0.1 | cloud_condensation_nuclei_0.1 | m-3 | each layer (S=0.1%) | |
| | ccn0.3 | cloud_condensation_nuclei_0.3 | m-3 | each layer (S=0.3%) | | | ccn0.3 | cloud_condensation_nuclei_0.3 | m-3 | each layer (S=0.3%) | |
| | sati | ice_supersaturation | 1 | Supersaturation with respect to ice | | | sati | ice_supersaturation | 1 | Supersaturation with respect to ice | |
| | wsubi | subgrid_vertical_velocity_for_cirrus | m s-1 | | | | wsubi | subgrid_vertical_velocity_for_cirrus | m s-1 | | |
| | cirrus_nso4 | sulfate_aerosol_number_for_homogeneous | m-3 | grid cell mean sulfate aerosol number used for homogeneous aerosol freezing for T<-37C | | | mmrdu | mass_fraction_of_dust_dry_aerosol_in_air | kg/kg | each layer | |
| | cirrus_ndust | dust_aerosol_number_for_heterogeneous | m-3 | grid cell mean dust aerosol number used for heterogeneous aerosol freezing for T<-37C | | | mmrbc | mass_fraction_of_black_carbon_dry_aerosol_in_air | kg/kg |each layer | |
| | cirrus_nbc | BC_aerosol_number_for_heterogeneous | m-3 | grid cell mean BC aerosol number used for heterogeneous aerosol freezing for T<-37C | | | mmrso4 | mass_fraction_of_sulfate_dry_aerosol_in_air | kg/kg | each layer | |
| | cirrus_nihom | homogeneous_nucleation_number | m-3 | grid cell mean ice crystal number production from homogeneous aerosol freezing for T<-37C during one model time step | | | cirrus_nso4 | sulfate_aerosol_number_for_homogeneous | m-3 | grid cell mean sulfate aerosol number used for homogeneous aerosol freezing even if ice not nucleated| |
| | cirrus_nihet | heterogeneous_nucleation_number | m-3 | grid cell mean ice crystal number production from heterogeneous aerosol freezing for T<-37C during one model time step | | | cirrus_ndust | dust_aerosol_number_for_heterogeneous | m-3 | grid cell mean dust aerosol number used for heterogeneous aerosol freezing even if ice not nucleated | |
| | cirrus_freqhom | homogeneous_nucleation_frequency | 1 | frequency counter of homogeneous aerosol freezing for T<-37C. For each time step, freqhom = 1 if homogeneous ice nucleation happens; otherwise freqhom = 0. Monthly average of this value indicates the homogeneous nucleation frequency. | | | cirrus_nbc | BC_aerosol_number_for_heterogeneous | m-3 | grid cell mean BC aerosol number used for heterogeneous aerosol freezing even if ice not nucleated | |
| | cirrus_freqhet | heterogeneous_nucleation_frequency | 1 | frequency counter of heterogeneous aerosol freezing for T<-37C. At each model time step, set freqhom = 1 if heterogeneous ice nucleation happens; otherwise freqhom = 0. Monthly average of this value indicates the heterogeneous nucleation frequency. | | | cirrus_nihom | homogeneous_nucleation_number | m-3 | grid cell mean ice crystal number production from homogeneous aerosol freezing for T%%<%%-37C during one model time step | |
| | | cirrus_nihet | heterogeneous_nucleation_number | m-3 | grid cell mean ice crystal number production from heterogeneous aerosol freezing for T%%<%%-37C during one model time step | |
| | | cirrus_freqhom | homogeneous_nucleation_frequency | 1 | frequency counter of homogeneous aerosol freezing for T%%<%%-37C. For each time step, freqhom = 1 if homogeneous ice nucleation happens; otherwise freqhom = 0. Monthly average of this value indicates the homogeneous nucleation frequency. | |
| | | cirrus_freqhet | heterogeneous_nucleation_frequency | 1 | frequency counter of heterogeneous aerosol freezing for T%%<%%-37C. At each model time step, set freqhom = 1 if heterogeneous ice nucleation happens; otherwise freqhom = 0. Monthly average of this value indicates the heterogeneous nucleation frequency. | |
| | mp_hetnuc | droplet_freezing_rate_by_heterogeneous | m-3 s-1 | grid cell mean freezing rate of cloud droplets in mixed-phase clouds for T>-37C | | | mp_hetnuc | droplet_freezing_rate_by_heterogeneous | m-3 s-1 | grid cell mean freezing rate of cloud droplets in mixed-phase clouds for T>-37C | |
| | mp_homnuc | droplet_freezing_rate_by_homogeneous | m-3 s-1 | grid cell mean instantaneous freezing rate of cloud droplets for T<=-37C | | | mp_homnuc | droplet_freezing_rate_by_homogeneous | m-3 s-1 | grid cell mean instantaneous freezing rate of cloud droplets for T<=-37C | |
| f3d(nx,nz) cloud fraction | f3d(nx,nz) cloud fraction |
| t3d(nx,nz) temperature | t3d(nx,nz) temperature |
| phase3d(nx,nz) cloud thermodynamic phase (0: entire cloud consists of ice, 1: entire cloud consists of liquid water, between 0 and 1: mixed-phase) | phase3d(nx,nz) cloud thermodynamic phase (0: entire cloud consists of ice, |
| cdr3d(nx,nz) cloud droplet effective radius | 1: entire cloud consists of liquid water, between 0 and 1: mixed-phase) |
| icr3d(nx,nz) ice crystal effective radius | phase3d could be from fice3d/f3d where fice3d=ice+mixed phase cloud fraction |
| cdnc3d(nx,nz) cloud droplet number concentration | cdr3d(nx,nz) in-cloud droplet effective radius |
| | icr3d(nx,nz) in-cloud ice crystal effective radius |
| | cdnc3d(nx,nz) in-cloud droplet number concentration |
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| thres_cld = 0.001 \\ | thres_cld = 0.001 \\ |
| ==== Q/A ==== | ==== Q/A ==== |
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| * 2D cloud fields (lwp, iwp, cdr, cdnc, ttop, cod): Please compute them from grid-box mean values at each level but DO NOT divide by the total (2D) cloud cover, which will be done in analysis after averaging in time and space. | * 2D cloud fields (lwp, iwp, cdr, cdnc, ttop, cod): Please save them as grid-box mean values but DO NOT divide by the total (2D) cloud cover, which will be done in analysis after averaging in time and space. |
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| * The three months 1 October - 31 December 2005 are thought as spin-up, which can of course be longer. Please choose as overlap assumption the one you use in the radiation scheme. | * The three months 1 October - 31 December 2005 are thought as spin-up, which can of course be longer. Please choose as overlap assumption the one you use in the radiation scheme. |