Project CAMS41 Phase 2
Implementation of CH4 wetland emissions in CTESSEL model

• CTESSEL plant functional types
• Wetland CH4 emission formulization
• CH4 emission data (used for validation)
• CTESSEL global optimization with 2 optimized parameters (s, q10)
• CTESSEL global optimization with 16 optimized parameters (s, q10 per PFT)
• CTESSEL global optimization with 18 optimized parameters (s per band, q10 per PFT)
• Comparison of optimization results

---

CTESSEL plant functional types

PFT	Number of pixels	Area, Mkm2	CH4 flux (GCP-2019), TgC/y
PFT1 Crops, mixed farming	56432 (23.63%)	15.36 (12.86%)	8.592 (9.47%)
PFT2 Short grass	25072 (10.5%)	10.56 (8.84%)	3 (3.31%)
PFT3 Evergreen needleleaf	22720 (9.51%)	6.95 (5.82%)	6.746 (7.44%)
PFT4 Deciduous needleleaf	12484 (5.23%)	3.09 (2.59%)	0.691 (0.76%)
PFT5 Deciduous broadleaf	19020 (7.96%)	5.42 (4.54%)	3.351 (3.69%)
PFT6 Evergreen broadleaf	25516 (10.68%)	14.38 (12.04%)	25.358 (27.96%)
PFT7 Tall grass	26996 (11.3%)	9.88 (8.27%)	8.024 (8.85%)
PFT9 Tundra	39624 (16.59%)	8.73 (7.31%)	2.58 (2.84%)
PFT10 Irrigated crops	10472 (4.38%)	3.7 (3.09%)	7.329 (8.08%)
PFT11 Semidesert	32796 (13.73%)	12.62 (10.57%)	0.816 (0.9%)
PFT13 Bogs and marshes	7436 (3.11%)	1.26 (1.06%)	2.447 (2.7%)
PFT16 Evergreen shrubs	3704 (1.55%)	0.97 (0.81%)	0.136 (0.15%)
PFT17 Deciduous shrubs	12924 (5.41%)	3.9 (3.27%)	1.925 (2.12%)
PFT18 Mixed forest - Wood	10740 (4.5%)	4.01 (3.36%)	2.413 (2.66%)
PFT19 Interrupted forest	73544 (30.79%)	18.6 (15.57%)	15.995 (17.6%)
not accounted			1.31 (1.44%)
Total	238 820	119.44	90.71
North (90N - 25N)	152988 (64.06%)	62.11 (52%)	28.750 (31.69%)
Tropics (25N - 25S)	69576 (29.13%)	47.69 (39.93%)	59.168 (65.23%)
South (25S - 90S)	16256 (6.81%)	9.69 (8.11%)	2.768 (3.05%)

---

Wetland CH4 emission formulization

\( f_\mathsf{CH4} = s \cdot f_\mathsf{wet} \cdot \mathsf{PRSOIL\_STR} \cdot q_{10}^{\frac{\mathsf{PTSOIL(1)-25}}{10}}\)

since PRSOIL_STR is also temperature-dependent:

\( \mathsf{PRSOIL\_STR} = \mathsf{FSN} \cdot \mathsf{FWCO2} \cdot \mathsf{RVR0VT} \cdot \mathsf{RQ}_{10}^{\frac{\mathsf{TSOIL}-25}{10}} \)

the formula has been changed to:

\( f_\mathsf{CH4} = s \cdot f_\mathsf{wet} \cdot \mathsf{FSN} \cdot \mathsf{FWCO2} \cdot \mathsf{RVR0VT} \cdot q_{10}^{\frac{\mathsf{PTSOIL(1)-25}}{10}}\)

CTESSEL variables used (routine SRFCOTWO)

• PRSOIL_STR (respiration from soil and structural biomass)
• PTSOIL (soil temperature per layer 1-4)
• TSOIL (average temperature over the 2 first layers)
• FSN (attenuation function for snow pack)
• FWCO2 (scaling factor accounting for soil moisture effect on respiration)
• RVR0VT (reference respiration tabulated by vegetation type)
• RQ10 (temperature dependency factor)

\( \mathsf{RQ}_{10} = 2.5665 - 0.05308 \cdot \mathsf{TSOIL} + 0.00238 \cdot \mathsf{TSOIL}^2 - 0.00004 \cdot \mathsf{TSOIL}^3 \)

Additional parametrization

• \( f_\mathsf{wet} \) (wetland extent fraction)
• \( q_{10} \) (temperature dependence factor)
• \( s \) (global scaling factor)

Global Wetland Extent Fraction

The data are taken from the ORCHIDEE-WET global simulation at 1°-resolution drived by ERA5 atmospherical forcing (2010-2016) conducted by S.Peng.
The fraction of wetland area was calibrated with GIEMS (Global Inundation Extent from Multi-Satellites) and Gumbricht et al. 2017 data (doi: 10.1111/gcb.13689).
The data in CTESSEL are used as monthly climatological dataset.

---

CH4 emission data (used for validation)

GCP-2019 inversion products
Mean/median across 11 products
Individual GCP-2019 products

---

CTESSEL global optimization with 2 optimized parameters (s, q10)

---

CTESSEL global optimization with 16 optimized parameters (s, q10 per PFT)

---

CTESSEL global optimization with 18 optimized parameters (s per band, q10 per PFT)

---

Comparison of optimization results

Parameter	Prior / Min / Max	Post (2 param)	Post (16 param)	Post (18 param)
Cost-function	3 179 808	2 677 576	2 557 460	2 457 930
RMSD	0.001807	0.001657	0.001620	0.001588
s_North	0.003300 min=0.000165 max=0.066	0.001886	0.002040	0.001419
s_Tropics				0.00261
s_South				0.00283
q10_PFT1	2.0 min=1.01 max=4.0	1.311	1.255	1.111
q10_PFT2			1.01	1.01
q10_PFT3			2.153	1.115
q10_PFT4			3.056	3.639
q10_PFT5			1.298	1.21
q10_PFT6			1.01	1.057
q10_PFT7			1.32	1.01
q10_PFT9			2.076	1.939
q10_PFT10			3.73	3.99
q10_PFT11			1.429	1.186
q10_PFT13			1.01	1.01
q10_PFT16			1.373	1.18
q10_PFT17			1.203	1.078
q10_PFT18			1.687	1.233
q10_PFT19			1.01	1.01