Lightning in CLM5.0, prescribed or interactive?

[Hemraj]

What version of the code are you using?
codebase=cesm2.2.0
Compset (for SSP3; and similar for SSP1): ISSP370Clm50Bgc (SSP370_DATM%GSWP3v1_CLM50%BGC_SICE_SOCN_MOSART_CISM2%NOEVOLVE_SWAV)
co2_type = 'diagnostic' (lnd_in)
"CLM_BLDNML_OPTS" value="-bgc bgc -megan -fire_emis" (env_run.xml)

Have you made any changes to files in the source tree?
NO

Describe your problem or question:
There is no problem, I wanted to understand how the model works. The main purpose of these simulations is to see how future changes in climate affect wildfires under SSP1 and SSP3. I kept population constant so, anthropogenic ignitation is fixed. I pass different meteorology for SSP1 and SSP3 to see their effect on wildfire:

user_nl_datm:
anomaly_forcing = 'Anomaly.Forcing.Precip','Anomaly.Forcing.Temperature','Anomaly.Forcing.Pressure','Anomaly.Forcing.Humidity','Anomaly.Forcing.Uwind','Anomaly.Forcing.Vwind','Anomaly.Forcing.Shortwave','Anomaly.Forcing.Longwave'

(SSP1)
streams = "datm.streams.txt.CLMGSWP3v1.Solar 2001 2001 2013",
"datm.streams.txt.CLMGSWP3v1.Precip 2001 2001 2013",
"datm.streams.txt.CLMGSWP3v1.TPQW 2001 2001 2013",
"datm.streams.txt.presaero.SSP1-2.6 1 2010 2010",
"datm.streams.txt.topo.observed 1 1 1",
"datm.streams.txt.co2tseries.SSP1-2.6 2015 2015 2500",
"datm.streams.txt.Anomaly.Forcing.Precip 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Temperature 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Pressure 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Humidity 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Uwind 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Vwind 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Shortwave 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Longwave 2015 2015 2100"

(SSP3)
streams = "datm.streams.txt.CLMGSWP3v1.Solar 2001 2001 2013",
"datm.streams.txt.CLMGSWP3v1.Precip 2001 2001 2013",
"datm.streams.txt.CLMGSWP3v1.TPQW 2001 2001 2013",
"datm.streams.txt.presaero.SSP3-7.0 1 2010 2010",
"datm.streams.txt.topo.observed 1 1 1",
"datm.streams.txt.co2tseries.SSP3-7.0 2015 2015 2500",
"datm.streams.txt.Anomaly.Forcing.Precip 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Temperature 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Pressure 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Humidity 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Uwind 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Vwind 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Shortwave 2015 2015 2100",
"datm.streams.txt.Anomaly.Forcing.Longwave 2015 2015 2100"


Light streams inside CaseDocs/lnd_in for both cases is:
&light_streams
lightngmapalgo = 'bilinear'
stream_fldfilename_lightng = '/CESM/input_data/atm/datm7/NASA_LIS/clmforc.Li_2012_climo1995-2011.T62.lnfm_Total_c140423.nc'
stream_year_first_lightng = 0001
stream_year_last_lightng = 0001
/

My question is, in addition to anthropogenic ignitions (which is fixed in this case), lightning is the another ignition source. It seems the lightning is prescribed for NASA_LIS as seen in lnd_in. I wonder whether this lighting data is just for initial condition or the model uses the same lightning data for whole period of simulation (my case runs from 2015 to 2100). Or is it the interactive lightning which is driven by future changes in meteorology obtained from SSP as shown above.

I need these details for better explaining my results. Thank you so much.

Best regards,
-Hemraj

 

[slevis]

A way to investigate this may be to look at the contents of the lightning file. Though just from the file name, I would conclude that the lightning data represent a 1995-2011 climatology. I am pretty confident that the model does not, yet, include interactive lightning driven by the meteorology.

 

[Hemraj]

Thank you so much @slevis. It is now clear that the lightning is prescribed (not interactive) and the model is using the same lightning data throughout the simulation. This also makes clear that whatever the changes in wildfires seen due to climate/meteorological changes are due to changes in fuel load and/or computability, but not due to changes in ignition/lightning frequencies.

The above .nc file contains three hourly lightning frequencies for a year.
"""
float lnfm[lon,lat,time]
long_name: lightning frequency
units: flash/km2/hr
mode: time-dependent
"""