Selecting parameters for CLM6-PPE

[linniahawkins]

Step 1: Identify the variables and processes in CLM of interest to the community for both tuning and uncertainty quantification. (google sheet)

Step 2: Use the CLM5-OAAT experiment (Kennedy et al., 2024) to identify parameters influential on the variables/processes of interest. (slide deck)

Step 3: Narrow down the parameter list to ~72 parameters and run a mini-OAAT ensemble (experimental design).

Step 4: Make some hard choices (discussion below).

Working parameter list

[linniahawkins]

Temperature sensitivity and acclimation of Vcmax, Jmax, TPU, and leaf maintenance respiration

Background (Bonan et al. 2011, Lombardozzi et al. 2015)

• Vcmax, Jmax, Tpu, Rd, Ko, Kc, Cp vary with leaf temperature according to the Arrhenius function. Only activation energy parameters are used in the Arrhenius function.

• Vcmax, Jmax, Tpu, Rd also have a high-temperature stress function (Leuning, 2002). Entropy and deactivation energy are used in the stress function.

• Vcmax, Jmax, Tpu all acclimate to a 10-day running mean of temperature. The vcmaxse_sf, jmaxse_sf, tpuse_sf parameters modify the acclimation sensitivity (entropy).

We coded up these functions in python to test parameter sensitivities offline google slides

Proposal:

1. Hold Kc,Ko,Cp parameters fixed. Hold deactivation energy parameters fixed.
2. Include all activation energy parameters for Vcmax, Jmax, TPU, & lmr
3. Group the acclimation scale factors into one parameter ACCLIM_SF (vcmaxse_sf, jmaxse_sf, tpuse_sf scaled simultaneously).