ORCHIDEE Development Section

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


CTESSEL plant functional types

PFT Number of pixels Area, Mkm2 CH4 flux (GCP-2019), TgC/y
PFT1 Crops, mixed farming56432 (23.63%)15.36 (12.86%)8.592 (9.47%)
PFT2 Short grass25072 (10.5%)10.56 (8.84%)3 (3.31%)
PFT3 Evergreen needleleaf22720 (9.51%)6.95 (5.82%)6.746 (7.44%)
PFT4 Deciduous needleleaf12484 (5.23%)3.09 (2.59%)0.691 (0.76%)
PFT5 Deciduous broadleaf19020 (7.96%)5.42 (4.54%)3.351 (3.69%)
PFT6 Evergreen broadleaf25516 (10.68%)14.38 (12.04%)25.358 (27.96%)
PFT7 Tall grass26996 (11.3%)9.88 (8.27%)8.024 (8.85%)
PFT9 Tundra39624 (16.59%)8.73 (7.31%)2.58 (2.84%)
PFT10 Irrigated crops10472 (4.38%)3.7 (3.09%)7.329 (8.08%)
PFT11 Semidesert32796 (13.73%)12.62 (10.57%)0.816 (0.9%)
PFT13 Bogs and marshes7436 (3.11%)1.26 (1.06%)2.447 (2.7%)
PFT16 Evergreen shrubs3704 (1.55%)0.97 (0.81%)0.136 (0.15%)
PFT17 Deciduous shrubs12924 (5.41%)3.9 (3.27%)1.925 (2.12%)
PFT18 Mixed forest - Wood10740 (4.5%)4.01 (3.36%)2.413 (2.66%)
PFT19 Interrupted forest73544 (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)

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

Additional parametrization

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