TROPOMI XCH4 retrievals – Official product TROPOMI/CH4-official

TROPOMI XCH4 retrievals – Official product TROPOMI/CH4-official#

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

  • 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#

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 “OFFICIAL”

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 0.5

Keep diagnostic group larger than 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

YAML template#

Please find below a template for a YAML configuration:

 1obsparser:
 2  plugin:
 3    name: TROPOMI
 4    version: CH4-official
 5    type: obsparser
 6
 7    # Optional arguments
 8    aggreg_freq: XXXXX  # str
 9    crop_domain:
10      xmin: XXXXX  # float
11      xmax: XXXXX  # float
12      ymin: XXXXX  # float
13      ymax: XXXXX  # float
14    nlayers: XXXXX  # float
15    obs_duration: XXXXX  # float
16    stationID: XXXXX  # str
17    networkID: XXXXX  # str
18    parameter: XXXXX  # str
19    std_max: XXXXX  # float
20    cloud_fraction_max: XXXXX  # float
21    aot_max: XXXXX  # float
22    chi2_max: XXXXX  # float
23    sza_max: XXXXX  # float
24    prec_max: XXXXX  # float
25    sr_max: XXXXX  # float
26    sa_min: XXXXX  # float
27    qa_value: XXXXX  # float
28    ws_min: XXXXX  # float
29    ws_max: XXXXX  # float
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