LAI sent to host has a forced minimum

[rgknox]

In EDCanopyStructureMod.F90:calc_areaindex() we impose an artificial minimum on all area indices. In other words, LAI/TAI/etc is not allowed to be lower than 0.1.

I think this is a pretty old artifact in the code, it has been left alone for this long just to retain B4B results in tests, but I think we really should remove this.

Its possible this was originally added to prevent a div0 somewhere, but we can find protections against this.

I could conceive that this minimum is generating some weird inconsistency that is affecting @jkshuman 's runs, but this is just a stab in the dark (might be worth testing its removal if no other ideas are generated).

[rosiealice]

Just going through my emails, wherein I found this issue. I agree we could test with removing these caps (which were indeed initially put in to avoid a /0 somewhere in the CLM surface exchange code) but maybe after the current crop of run time issues have gone away?

On 14 August 2017 at 19:14, Ryan Knox notifications@github.com wrote:

In EDCanopyStructureMod.F90:calc_areaindex() we impose an artificial minimum on all area indices. In other words, LAI/TAI/etc is not allowed to be lower than 0.1.

I think this is a pretty old artifact in the code, it has been left alone for this long just to retain B4B results in tests, but I think we really should remove this.

Its possible this was originally added to prevent a div0 somewhere, but we can find protections against this.

I could conceive that this minimum is generating some weird inconsistency that is affecting @jkshuman https://github.com/jkshuman 's runs, but this is just a stab in the dark (might be worth testing its removal if no other ideas are generated).

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[ckoven]

this is the same issue (or a subset anyway) as #101, right? so then that problem still exists?

[ckoven]

reopening this because of #739

[glemieux]

After checking to see if we could simply remove this again per the discussion https://github.com/NGEET/fates/discussions/1007#discussioncomment-5457762, testing shows that this is still and issue. I'm seeing a floating point error for threaded aux_clm suite test SMS_D_Lm6_P144x1.f45_f45_mg37.I2000Clm50FatesRs.cheyenne_intel.clm-FatesCold:

...
49699 102:MPT: #2  MPI_SGI_stacktraceback (
49700 102:MPT:     header=header@entry=0x7ffdc2c860d0 "MPT ERROR: Rank 102(g:102) received signal SIGFPE(8).\n\tProcess ID: 55323, Host: r13i3n34, Program: /glade/scratch/glemieux/ctsm-tests      /tests_ai-min-remove-aux-3/SMS_D_Lm6_P144x1.f45_f45_mg37.I2000Clm50"...) at sig.c:340
49701 102:MPT: #3  0x00002b2d04b8fe66 in first_arriver_handler (signo=signo@entry=8,
49702 102:MPT:     stack_trace_sem=stack_trace_sem@entry=0x2b2d14480080) at sig.c:489
49703 102:MPT: #4  0x00002b2d04b900f3 in slave_sig_handler (signo=8, siginfo=<optimized out>,
49704 102:MPT:     extra=<optimized out>) at sig.c:565
49705 102:MPT: #5  <signal handler called>
49706 102:MPT: #6  0x00000000018ed580 in edsurfaceradiationmod::ed_sunshadefracs (nsites=10,
49707 102:MPT:     sites=..., bc_in=..., bc_out=...)
49708 102:MPT:     at /glade/u/home/glemieux/ctsm/src/fates/biogeophys/EDSurfaceAlbedoMod.F90:1266
...

The fates suite test ERS_Lm13.f10_f10_mg37.I2000Clm50Fates.cheyenne_gnu.clm-FatesCold is failing during the TotalBalanceCheck call due to aresp_acc being NaN:

5751 49: ENDRUN:ERROR in /glade/u/home/glemieux/ctsm/src/fates/main/EDMainMod.F90 at line 1013
...
65286 49: mass balance error detected
65287 49: element type (see PRTGenericMod.F90):            1
65288 49: error fraction relative to biomass stock:    0.0000000000000000
65289 49: absolut error (flux in - change):                        NaN
65290 49: call index:            1
65291 49: Element index (PARTEH global):           1
65292 49: net:                        NaN
65293 49: dstock:  -0.16263594704082607
65294 49: seed_in:    0.0000000000000000
65295 49: net_root_uptake:    0.0000000000000000
65296 49: gpp_acc:    1.8726980289346781E-003
65297 49: flux_generic_in:    0.0000000000000000
65298 49: wood_product:    0.0000000000000000
65299 49: error from patch resizing:    0.0000000000000000
65300 49: burn_flux_to_atm:    0.0000000000000000
65301 49: seed_out:    0.0000000000000000
65302 49: flux_generic_out:    0.0000000000000000
65303 49: frag_out:    1.4318040557578071E-002
65304 49: aresp_acc:                        NaN
65305 49: error=net_flux-dstock:                       NaN
65306 49: biomass   293.76402263977747
65307 49: litter   663.48754971364178
65308 49: seeds   9.8703240123981963
65309 49: total stock   967.12189636581752
65310 49: previous total   967.28453231285835
65311 49: lat lon  -70.000000000000000        15.000000000000000
65312 49: ---------------------------------------

[rgknox]

@glemieux , for the SIGFPE(8) fail, can you confirm that line 1266 in the error matches this line from the recent tag:

https://github.com/NGEET/fates/blob/sci.1.65.3_api.25.4.0/biogeophys/EDSurfaceAlbedoMod.F90#L1266

[glemieux]

@rgknox confirmed :+1: