# S5P_L2_CH4

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of S5P_L2_CH4 data.

field name

type

dimensions

unit

description

scan_subindex

int16

{time}

pixel index (0-based) within the scanline

datetime_start

double

{time}

[seconds since 2010-01-01]

start time of the measurement

datetime_length

double

[s]

duration of the measurement

orbit_index

int32

absolute orbit number

validity

int32

{time}

processing quality flag

latitude

float

{time}

[degree_north]

latitude of the ground pixel center (WGS84)

longitude

float

{time}

[degree_east]

longitude of the ground pixel center (WGS84)

latitude_bounds

float

{time, 4}

[degree_north]

latitudes of the ground pixel corners (WGS84)

longitude_bounds

float

{time, 4}

[degree_east]

longitudes of the ground pixel corners (WGS84)

sensor_latitude

float

{time}

[degree_north]

latitude of the geodetic sub-satellite point (WGS84)

sensor_longitude

float

{time}

[degree_east]

longitude of the goedetic sub-satellite point (WGS84)

sensor_altitude

float

{time}

[m]

altitude of the satellite with respect to the geodetic sub-satellite point (WGS84)

solar_zenith_angle

float

{time}

[degree]

zenith angle of the Sun at the ground pixel location (WGS84); angle measured away from the vertical

solar_azimuth_angle

float

{time}

[degree]

azimuth angle of the Sun at the ground pixel location (WGS84); angle measured East-of-North

sensor_zenith_angle

float

{time}

[degree]

zenith angle of the satellite at the ground pixel location (WGS84); angle measured away from the vertical

sensor_azimuth_angle

float

{time}

[degree]

azimuth angle of the satellite at the ground pixel location (WGS84); angle measured East-of-North

altitude_bounds

float

{time, vertical, 2}

[m]

altitude bounds per profile layer

pressure_bounds

float

{time, vertical, 2}

[Pa]

pressure bounds per profile layer

surface_altitude

float

{time}

[m]

surface altitude

surface_altitude_uncertainty

float

{time}

[m]

surface altitude precision

surface_pressure

float

{time}

[Pa]

surface pressure

surface_meridional_wind_velocity

float

{time}

[m/s]

northward wind

surface_zonal_wind_velocity

float

{time}

[m/s]

eastward wind

CH4_column_volume_mixing_ratio_dry_air

float

{time}

[ppbv]

column averaged dry air mixing ratio of methane

CH4_column_volume_mixing_ratio_dry_air_uncertainty

float

{time}

[ppbv]

uncertainty of the column averaged dry air mixing ratio of methane (1 sigma error)

CH4_column_volume_mixing_ratio_dry_air_validity

int8

{time}

continuous quality descriptor, varying between 0 (no data) and 100 (full quality data)

CH4_column_number_density_avk

float

{time, vertical}

[]

column averaging kernel for methane retrieval

CH4_column_number_density_apriori

float

{time, vertical}

[mol/m2]

a-priori column number density profile of methane

dry_air_column_number_density

float

{time, vertical}

[mol/m2]

column number density profile of dry air

H2O_column_number_density

float

{time}

[mol/m^2]

H2O total column density

H2O_column_number_density_uncertainty

float

{time}

[mol/m^2]

uncertainty of the H2O column density (standard error)

cloud_fraction

float

{time}

[]

cloud fraction from VIIRS data in the SWIR channel for the instantaneous field of view

aerosol_height

float

{time}

[m]

aerosol height parameter in the CH4 retrieval

aerosol_optical_depth

float

{time}

[]

aerosol optical thicknesss in the SWIR band

surface_albedo

float

{time}

[]

surface albedo in the SWIR channel

surface_albedo_uncertainty

float

{time}

[]

precision of the surface albedo in the SWIR channel

index

int32

{time}

zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for S5P_L2_CH4 products.

option name

legal values

description

ch4

bias_corrected

whether to ingest the ‘normal’ CH4 column vmr (default) or the bias corrected CH4 column vmr (ch4=bias_corrected)

## Mapping description

The table below details where and how each variable was retrieved from the input product.

field name

mapping description

scan_subindex

description

the scanline and pixel dimensions are collapsed into a temporal dimension; the index of the pixel within the scanline is computed as the index on the temporal dimension modulo the number of scanlines

datetime_start

path

/PRODUCT/time, /PRODUCT/delta_time[]

description

time converted from milliseconds since a reference time (given as seconds since 2010-01-01) to seconds since 2010-01-01 (using 86400 seconds per day); the time associated with a scanline is repeated for each pixel in the scanline

datetime_length

path

/@time_coverage_resolution

description

the measurement length is parsed assuming the ISO 8601 ‘PT%(interval_seconds)fS’ format

orbit_index

path

/@orbit

validity

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/processing_quality_flags[]

description

the uint32 data is cast to int32

latitude

path

/PRODUCT/latitude[]

longitude

path

/PRODUCT/longitude[]

latitude_bounds

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/latitude_bounds[]

longitude_bounds

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/longitude_bounds[]

sensor_latitude

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/satellite_latitude[]

description

the satellite latitude associated with a scanline is repeated for each pixel in the scanline

sensor_longitude

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/satellite_longitude[]

description

the satellite longitude associated with a scanline is repeated for each pixel in the scanline

sensor_altitude

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/satellite_altitude[]

description

the satellite altitude associated with a scanline is repeated for each pixel in the scanline

solar_zenith_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/solar_zenith_angle[]

solar_azimuth_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/solar_azimuth_angle[]

sensor_zenith_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/viewing_zenith_angle[]

sensor_azimuth_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/viewing_azimuth_angle[]

altitude_bounds

condition

processor version >= 01.00.00

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/altitude_levels[]

description

derived from height per level (layer boundary) by repeating the inner levels; the upper bound of layer k is equal to the lower bound of layer k+1; the vertical grid is inverted to make it ascending

condition

processor version < 01.00.00

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/height_levels[]

description

derived from height per level (layer boundary) by repeating the inner levels; the upper bound of layer k is equal to the lower bound of layer k+1; the vertical grid is inverted to make it ascending

pressure_bounds

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_pressure[],/PRODUCT/SUPPORT_DATA/INPUT_DATA/pressure_interval[]

description

derived from surface pressure and pressure difference between retrieval levels (the pressure grid is equidistant between the surface pressure and a fixed top pressure); given a zero-based layer index k, the pressure bounds for layer k are derived as: (surface_pressure - k * pressure_interval, surface_pressure - (k + 1) * pressure_interval); the vertical grid is inverted to make it ascending

surface_altitude

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_altitude[]

surface_altitude_uncertainty

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_altitude_precision[]

surface_pressure

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_pressure[]

surface_meridional_wind_velocity

available

optional

condition

processor version >= 01.03.00

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/northward_wind[]

surface_zonal_wind_velocity

available

optional

condition

processor version >= 01.03.00

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/eastward_wind[]

CH4_column_volume_mixing_ratio_dry_air

condition

ch4 unset

path

/PRODUCT/methane_mixing_ratio[]

condition

ch4=bias_corrected

path

/PRODUCT/methane_mixing_ratio_bias_corrected[]

CH4_column_volume_mixing_ratio_dry_air_uncertainty

path

/PRODUCT/methane_mixing_ratio_precision[]

CH4_column_volume_mixing_ratio_dry_air_validity

path

/PRODUCT/qa_value

CH4_column_number_density_avk

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/column_averaging_kernel[]

description

the vertical grid is inverted to make it ascending

CH4_column_number_density_apriori

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/methane_profile_apriori[]

description

the vertical grid is inverted to make it ascending

dry_air_column_number_density

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/dry_air_subcolumns[]

description

the vertical grid is inverted to make it ascending

H2O_column_number_density

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/water_total_column[]

H2O_column_number_density_uncertainty

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/water_total_column_precision[]

cloud_fraction

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/cloud_fraction_VIIRS_SWIR_IFOV[]

aerosol_height

condition

processor version >= 01.00.00

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/aerosol_mid_altitude[]

condition

processor version < 01.00.00

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/aerosol_mid_height[]

aerosol_optical_depth

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/aerosol_optical_thickness_SWIR[]

surface_albedo

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/surface_albedo_SWIR[]

surface_albedo_uncertainty

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/surface_albedo_SWIR_precision[]