This repository is a global methane emission assimilation system based on an Ensemble Kalman Filter (EnKF) framework and the GEOS-Chem Global Chemical Transport Model (v12.5.0). It is an updated version of the ESA PyOSSE: Package for Observation System Simulation Experiments developed by Liang Feng. We have converted the original FORTRAN modules to Python scripts for better use and easier update.
Included in this repository are:
- Tag run program to create the Jacobian matrix needed for the EnKF;
- Zip file for GEOS-Chem v12.5.0 and user-updated global_ch4_mod.F for an easier way to define the tag run;
- Scripts to create inversion run directory, GEOS-Chem rerun directory and diagnosis directories;
- Configuration files that specify inversion options and diagnosis options;
- Scripts to run GEOS-Chem tests;
- Scripts for CH4 observations, including GOSAT, TROPOMI, NOAA, TCCON;
- Scripts to correct GEOS-Chem CH4 latitudinal biases during inversion; and
- Main Driver routines.
We acknowledge the GEOS-Chem community, in particular the Harvard University team that helps maintain the GEOS-Chem model, and the NASA Global Modelling and Assimilation Office (GMAO) for providing the MERRA2 data product.
- http://wiki.seas.harvard.edu/geos-chem/index.php/Main_Page/
- https://github.com/geoschem/
- https://github.com/geoschem/GEOSChem-python-tutorial
# Python environment installation
$ conda env create -vv -n idp -f enkf_environment.yml
$ source activate idp# configuration
$ cd .../global_tagrun/code/
$ vim geos_chem_def.py
# tag run
$ ./enkf_drive_sh.py# configuration
$ vim /obs/operator_config.py ## Observation options
$ cd .../enkf/
$ vim geos_chem_def.py ## inversion options and diagnosis path
$ vim restart_config.py
# inversion run
$ ./etkf_main.py
| Data | Usage | Official Access |
|---|---|---|
| NOAA ObsPack products | In-situ CH4 recordings for inversion | Global Monitoring Laboratory (noaa.gov) |
| GOSAT Proxy XCH4 data(v9.0) | GOSAT XCH4 retrievals for inversion | University of Leicester GOSAT Proxy XCH4 v9.0 |
| ACE-FTS CH4 profiles(v4.1) | CH4 profiles for GEOS-chem latitudinal bias correction | Data access and Data quality flags |
| TCCON data | In-situ XCH4 measurements for validation | TCCON Data Archive |
We appreciate all of the scientists and professionals who contributed to the datasets listed above.
The decadal mean difference between GOSAT-retrieved methane column concentrations (XCH4) and those simulated using GEOS-Chem with a priori emissions at 4x5 (R4, a) and 2x2.5 (R2, b) scales and using a posteriori emissions after inversion at grid scales of R4 (c) and R2 (d).
Decadal mean distribution of a priori and a posteriori methane emissions in using R4 (a, d) and the R2 (b, e) inversions and their differences (a posteriori minus a priori) (c, f).
Annual mean variations of global total methane emissions (a) in R4 (blue) and R2 (orange) versions of the GEOS-Chem model and their monthly variations (b) from 2010 to 2019.
Global annual total emissions during the 2010s (Tg/yr).
Taylor diagrams of statistical results (correlation coefficient, standard deviation, and root-mean-square deviation (RMSD)) between surface-measured methane column concentrations (XCH4) from the TCCON network and those simulated using GEOS-Chem with a priori emissions at R4 (a) and R2 (b), and using a posteriori emissions after inversion at R4 (c) and R2 (d) (Deep blue: latitudes of TCCON sites are larger than 60°N; Green: the latitudes of sites are within 45° – 60°N; Yellow: the latitudes of sites are within 30° – 45°N; Red: the latitudes of sites are within –15°S – 45°N; Blue: The sites located in the mid-latitudes of SH).
[1] Feng, L., Palmer, P.I., Bösch, H. and Dance, S., 2009. Estimating surface CO 2 fluxes from space-borne CO 2 dry air mole fraction observations using an ensemble Kalman Filter. Atmospheric chemistry and physics, 9(8), 2619−2633, https://doi.org/10.5194/acp-9-2619-2009.
[2] Feng, L., Palmer, P.I., Bösch, H., Parker, R.J., Webb, A.J., Correia, C.S., Deutscher, N.M., Domingues, L.G., Feist, D.G., Gatti, L.V. and Gloor, E., 2017. Consistent regional fluxes of CH 4 and CO 2 inferred from GOSAT proxy XCH 4: XCO 2 retrievals, 2010–2014. Atmospheric chemistry and physics, 17(7), 4781−4797, https://doi.org/10.5194/acp-17-4781-2017.
[3] Zhu, S., Feng, L., Liu, Y., Wang, J. and Yang, D., 2022. Decadal Methane Emission Trend Inferred from Proxy GOSAT XCH4 Retrievals: Impacts of Transport Model Spatial Resolution. Advances in Atmospheric Sciences, 39(8), 1343-1359, https://doi.org/10.1007/s00376-022-1434-6.