TROPOMI XCH4 retrievals from SRON TROPOMI/CH4-SRON#
Description#
This plugin reads TROPOMI XCH4 retrievals as provided by SRON. Data can be downloaded here: `https://ftp.sron.nl/open-access-data-2/TROPOMI/tropomi/ch4/19_446/`__.
The data is described in Lorente et al. (2021)
For filtering data, the product User Guide mentions that:
- The most relevant filtering criteria are:
Cloud fraction < 0.001 (IFOV, OFOV)
Ratio weak and strong CH 4 column 0.85 - 1.15
Standard deviation of ratio weak and strong CH 4 column < 0.05
Aerosol optical thickness (NIR) < 0.3 (see User Guide, more recent than Lorente et al. in which this criteria is AOT (SWIR) < 0.1)
chi2 < 100
Solar zenith angle < 70
Precision < 10 ppb
Surface roughness < 80 m
Surface albedo (SWIR) > 0.02 (only land)
with the parameter ’qa_value’ in the diagnostics group equal to 1
YAML arguments#
The following arguments are used to configure the plugin. pyCIF will return an exception at the initialization if mandatory arguments are not specified, or if any argument does not fit accepted values or type:
Optional arguments#
- orbit_range : optional
Range of orbit IDs to cover
- Argument structure:
- orb_min : int, optional, default -10
Minimum orbit ID
- orb_max : int, optional, default 10000000
Minimum orbit ID
- aggreg_freq : str, optional, default “1D”
Frequency at which to aggregate files into intermediate monitor file
- crop_domain : optional
Domain where to keep data. Data outside are discarded
- Argument structure:
- xmin : float, mandatory
West boundary
- xmax : float, mandatory
East boundary
- ymin : float, mandatory
South boundary
- ymax : float, mandatory
North boundary
- nlayers : float, optional, default 12
Number of layers expected in the averaging kernels
- obs_duration : float, optional, default 0.016666666666666666
Duration of each observation
- stationID : str, optional, default “TROPOMI”
Name to put in the ‘station’ column of the output parsed datastore
- networkID : str, optional, default “KNMI-SRON”
Name to put in the ‘network’ column of the output parsed datastore
- parameter : str, optional, default “CH4”
Name of the species to put in the ‘parameter’ column of the output parsed datastore
- std_max : float, optional, default 0.05
Threshold for standard deviation of ratio weak and strong CH4 column
- cloud_fraction_max : float, optional, default 0.001
Maximum threshold for cloud fraction
- aot_max : float, optional, default 0.3
Aerosol optical thickness (NIR)
- chi2_max : float, optional, default 100
Threshold for chi-square value
- sza_max : float, optional, default 70
Solar zenith angle
- prec_max : float, optional, default 10
Precision threshold
- sr_max : float, optional, default 80
Maximum surface roughness
- sa_min : float, optional, default 0.02
Minimum surface albedo (SWIR) to keep land only
- qa_value : float, optional, default 1
Keep diagnostic group equal to qa_value
- ws_min : float, optional, default 0.85
Minimum ratio weak and strong CH4 column
- ws_max : float, optional, default 1.15
Maximum ratio weak and strong CH4 column
- balb_max : float, optional, default 0.8
Maximum blended albedo
YAML template#
Please find below a template for a YAML configuration:
1obsparser:
2 plugin:
3 name: TROPOMI
4 version: CH4-SRON
5 type: obsparser
6
7 # Optional arguments
8 orbit_range:
9 orb_min: XXXXX # int
10 orb_max: XXXXX # int
11 aggreg_freq: XXXXX # str
12 crop_domain:
13 xmin: XXXXX # float
14 xmax: XXXXX # float
15 ymin: XXXXX # float
16 ymax: XXXXX # float
17 nlayers: XXXXX # float
18 obs_duration: XXXXX # float
19 stationID: XXXXX # str
20 networkID: XXXXX # str
21 parameter: XXXXX # str
22 std_max: XXXXX # float
23 cloud_fraction_max: XXXXX # float
24 aot_max: XXXXX # float
25 chi2_max: XXXXX # float
26 sza_max: XXXXX # float
27 prec_max: XXXXX # float
28 sr_max: XXXXX # float
29 sa_min: XXXXX # float
30 qa_value: XXXXX # float
31 ws_min: XXXXX # float
32 ws_max: XXXXX # float
33 balb_max: XXXXX # float