Multiple updates to drought deciduous phenology #801

mpaiao · 2021-10-30T03:16:54Z

Added new options and controls for drought deciduous phenology

Description:

First set of changes in the drought deciduous phenology to improve its predictability.

Implemented option to drive leaves on / leaves off using soil matric potential instead of soil water content, which is more intuitive for setting up thresholds. The choice is controlled by fates_phen_drought_threshold: when it is positive, it continues to use the soil volumetric water content (m3/m3), and when it is negative, it uses soil matric potential (in mm).
When drought-deciduous leaves are off, the plant now stops allocating carbon to fine roots to reduce carbon losses when carbon balance is necessarily non-positive.
Revised variable sapw_memory and struct_memory. The name referred to the target value, but the variable was storing the losses, and thus inconsistent with leafmemory (formerly laimemory, see Replaced variable laimemory with leafmemory #865). All of these, along with the new fnrtmemory now store the carbon pool prior to leaf shedding.
The drought-deciduous status is still done at the site level but now it is PFT-dependent because the root distribution is PFT dependent. This required turning a few site-level variables into site x PFT.
Sub-routine phenology_leafonoff (EDPhysiologyMod.F90) was rewritten to reduce duplicated code. Most of the steps for cold deciduous and drought deciduous were the same. The revised routine first checks whether or not it is time o flush or shed leaves, then it uses a common set of commands.

Collaborators:

Discussions with @rgknox @ckoven @rosiealice @jkshuman @XiulinGao

Expectation of Answer Changes:

These changes should affect the code when running with drought deciduous phenology. The code now uses a different approach to find moisture threshold (rooting zone and optionally, matric potential), and the carbon allocation strategies changed during the leaf-off periods.

Checklist:

My change requires a change to the documentation.
I have updated the in-code documentation .AND. (the technical note .OR. the wiki) accordingly.
I have read the CONTRIBUTING document.
FATES PASS/FAIL regression tests were run
If answers were expected to change, evaluation was performed and provided

Test Results:

CTSM (or) E3SM (specify which) test hash-tag:

CTSM (or) E3SM (specify which) baseline hash-tag:

FATES baseline hash-tag:

Test Output:

1. Bug fix in DailyPRTAllometricCarbon (parteh/PRTAllometricCarbonMod.F90). When allocating to different tissues, the code was subtracting allocation of tissues before calculating the amount for the next tissue, potentially under-allocating carbon to fine roots. 2. Renamed variable laimemory with leafmemory. We were never tracking the LAI, but leaf carbon, and thus the name is dangerously misleading. 3. Implemented an option carbon allocation routine (DailyPRTAllometricCarbonSimpler in parteh/PRTAllometricCarbonMod.F90). In this routine, I applied much simpler rules for maintenance allocation: it simply checks how much each pool is in deficit, and allocates carbon (storage + carbon_balance) to the pools according to the debt. If there is any carbon left, then the plant finishes filling the storage pool and then allocates to growth.

…s predictability. 1. Implemented option to drive leaves on / leaves off using soil matric potential instead of soil water content, which is more intuitive for setting up thresholds. The choice is controlled by fates_phen_drought_threshold: when it is positive, it continues to use the soil volumetric water content (m3/m3), and when it is negative, it uses soil matric potential (in mm). 2. When drought-deciduous leaves are off, the plant now stops allocating carbon to any living tissue, to reduce carbon losses when carbon balance is necessarily non-positive. 3. The drought-deciduous status is still done at the site level but now it is PFT-dependent because the root distribution is PFT dependent. This required turning 5 site-level variables into site x PFT. 4. Sub-routine phenology_leafonoff (EDPhysiologyMod.F90) was rewritten to reduce duplicated code. Most of the steps for cold deciduous and drought deciduous were the same. The revised routine first checks whether or not it is time o flush or shed leaves, then it uses a common set of commands.

…efinitions of sapwood and structural memory.

…t-decid

…on approach.

…arbon-alloc

…f with end select). And now all tests for hlm_parteh_mode use select case, which is safer for options in any case.

I updated the soil moisture / soil matric potential variable to skip the topmost layer. I did not change the rooting depth profile, instead I simply ignored the contribution of the top most layer. This layer dries out rather quickly and experience very negative values, which ultimately keeps plants under "leaves off" state for too long.

rosiealice · 2021-11-15T20:51:55Z