QA4ECV_L2_NO2

Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of QA4ECV_L2_NO2 data.

field name

type

dimensions

unit

description

scan_subindex

int16

{time}

pixel index (0-based) within the scanline

datetime

double

{time}

[seconds since 1995-01-01]

start time of the measurement

orbit_index

int32

absolute orbit number

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)

solar_zenith_angle

float

{time}

[degree]

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

relative_azimuth_angle

float

{time}

[degree]

relative azimuth angle 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

surface_altitude

float

{time}

[m]

surface altitude

surface_pressure

float

{time}

[hPa]

surface pressure

pressure_bounds

double

{time, vertical, 2}

[Pa]

pressure boundaries for each layer

cloud_fraction

float

{time}

[]

cloud fraction

cloud_fraction_uncertainty

float

{time}

[]

effective cloud fraction uncertainty

cloud_pressure

float

{time}

[hPa]

cloud optical centroid pressure from the cloud product

cloud_pressure_uncertainty

float

{time}

[hPa]

cloud optical centroid pressure from the cloud product

snow_ice_type

int8

{time}

surface snow/ice type; enumeration values: snow_free_land (0), sea_ice (1), permanent_ice (2), snow (3), ocean (4)

sea_ice_fraction

float

{time}

[]

sea-ice concentration (as a fraction)

tropopause_pressure

double

{time}

[Pa]

tropopause pressure

tropospheric_NO2_column_number_density

float

{time}

[molec/cm^2]

tropospheric vertical column of NO2

tropospheric_NO2_column_number_density_uncertainty

float

{time}

[molec/cm^2]

uncertainty of the tropospheric vertical column of NO2 (standard error)

tropospheric_NO2_column_number_density_avk

float

{time, vertical}

[]

averaging kernel for the tropospheric vertical column number density of NO2

tropospheric_NO2_column_number_density_amf

float

{time}

[]

tropospheric air mass factor, computed by integrating the altitude dependent air mass factor over the atmospheric layers from the surface up to and including the layer with the tropopause

stratospheric_NO2_column_number_density

float

{time}

[molec/cm^2]

stratospheric vertical column of NO2

stratospheric_NO2_column_number_density_uncertainty

float

{time}

[molec/cm^2]

uncertainty of the stratospheric vertical column of NO2 (standard error)

stratospheric_NO2_column_number_density_avk

float

{time, vertical}

[]

averaging kernel for the stratospheric vertical column number density of NO2

stratospheric_NO2_column_number_density_amf

float

{time}

[]

stratospheric air mass factor

NO2_column_number_density

float

{time}

[molec/cm^2]

total vertical column of NO2 (ratio of the slant column density of NO2 and the total air mass factor)

NO2_column_number_density_uncertainty

float

{time}

[molec/cm^2]

uncertainty of the total vertical column of NO2 (standard error)

NO2_column_number_density_amf

float

{time}

[]

total air mass factor, computed by integrating the altitude dependent air mass factor over the atmospheric layers from the surface to top-of-atmosphere

NO2_column_number_density_avk

float

{time, vertical}

[]

averaging kernel for the total column number density of NO2

surface_albedo

float

{time}

[]

surface albedo in the NO2 fitting window

validity

int32

{time}

processing quality flag

index

int32

{time}

zero-based index of the sample within the source product

Ingestion options

The table below lists the available ingestion options for QA4ECV_L2_NO2 products.

option name

legal values

description

total_column

summed, total

whether to use total_no2_vertical_column (which is derived from the total slant column diveded by the total amf) or summed_no2_total_vertical_column (which is the sum of the retrieved tropospheric and stratospheric columns); option values are ‘summed’ (default) and ‘total’

stratospheric_column

stream

whether to use the default NO2 stratospheric column (default) or the stratospheric column estimated with the STREAM method (stratospheric_column=stream)

cloud_fraction

radiance

whether to ingest the cloud fraction (default) or the radiance cloud fraction (cloud_fraction=radiance)

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

path

/PRODUCT/time, /PRODUCT/delta_time[]

description

time converted from milliseconds since a reference time (with the reference time being 1995-01-01) to seconds since 1995-01-01; the time associated with a scanline is repeated for each pixel in the scanline

orbit_index

path

/@orbit

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[]

solar_zenith_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/solar_zenith_angle[]

relative_azimuth_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/relative_azimuth_angle[]

sensor_zenith_angle

path

/PRODUCT/SUPPORT_DATA/GEOLOCATIONS/viewing_zenith_angle[]

surface_altitude

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_altitude[]

surface_pressure

path

/PRODUCT/tm5_surface_pressure[]

pressure_bounds

path

/PRODUCT/tm5_pressure_level_a[], /PRODUCT/tm5_pressure_level_b[], /PRODUCT/tm5_surface_pressure[]

description

pressure in Pa at level k is derived from surface pressure in hPa as: tm5_pressure_level_a[k] + tm5_pressure_level_b[k] * tm5_surface_pressure[] * 100.0; the TOA pressure is clamped to 1e-3 Pa

cloud_fraction

condition

cloud_fraction unset

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/cloud_fraction[]

condition

cloud_fraction=radiance

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/cloud_radiance_fraction_no2[]

cloud_fraction_uncertainty

available

optional

condition

cloud_fraction unset

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/cloud_fraction_uncertainty[]

cloud_pressure

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/cloud_pressure[]

cloud_pressure_uncertainty

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/cloud_pressure_uncertainty[]

snow_ice_type

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/snow_ice_flag[]

description

0: snow_free_land (0), 1-100: sea_ice (1), 101: permanent_ice (2), 103: snow (3), 255: ocean (4), other values map to -1

sea_ice_fraction

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/snow_ice_flag[]

description

if 1 <= snow_ice_flag <= 100 then snow_ice_flag/100.0 else 0.0

tropopause_pressure

path

/PRODUCT/tm5_pressure_level_a[], /PRODUCT/tm5_pressure_level_b[], /PRODUCT/tm5_surface_pressure[], /PRODUCT/tm5_tropopause_layer_index[]

description

pressure in Pa at tropause is derived from the upper bound of the layer with tropopause layer index k: tm5_pressure_level_a[k + 1] + tm5_pressure_level_b[k + 1] * tm5_surface_pressure[] * 100.0

tropospheric_NO2_column_number_density

path

/PRODUCT/tropospheric_no2_vertical_column[]

tropospheric_NO2_column_number_density_uncertainty

path

/PRODUCT/tropospheric_no2_vertical_column_uncertainty[]

tropospheric_NO2_column_number_density_avk

path

/PRODUCT/averaging_kernel[], /PRODUCT/amf_total[], /PRODUCT/amf_trop[], /PRODUCT/tm5_tropopause_layer_index[]

description

averaging_kernel[layer] = if layer <= tm5_tropopause_layer_index then averaging_kernel[layer] * amf_total / amf_trop else 0

tropospheric_NO2_column_number_density_amf

path

/PRODUCT/amf_trop[]

stratospheric_NO2_column_number_density

condition

stratospheric_column unset

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/stratospheric_no2_vertical_column[]

condition

stratospheric_column=stream

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/stratospheric_no2_vertical_column_stream[]

stratospheric_NO2_column_number_density_uncertainty

condition

stratospheric_column unset

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/stratospheric_no2_vertical_column_uncertainty[]

condition

stratospheric_column=stream

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/stratospheric_no2_vertical_column_stream_uncertainty[]

stratospheric_NO2_column_number_density_avk

path

/PRODUCT/averaging_kernel[], /PRODUCT/amf_total[], /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/amf_strat[], /PRODUCT/tm5_tropopause_layer_index[]

description

averaging_kernel[layer] = if layer > tm5_tropopause_layer_index then averaging_kernel[layer] * amf_total / amf_strat else 0

stratospheric_NO2_column_number_density_amf

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/amf_strat[]

NO2_column_number_density

condition

total_column=summed or total_column unset

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/summed_no2_total_vertical_column[]

condition

total_column=total

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/total_no2_vertical_column[]

NO2_column_number_density_uncertainty

condition

total_column=summed or total_column unset

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/summed_no2_total_vertical_column_uncertainty[]

condition

total_column=total

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/total_no2_vertical_column_uncertainty[]

NO2_column_number_density_amf

path

/PRODUCT/amf_total[]

NO2_column_number_density_avk

path

/PRODUCT/averaging_kernel[]

surface_albedo

path

/PRODUCT/SUPPORT_DATA/INPUT_DATA/surface_albedo_no2[]

validity

path

/PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/processing_quality_flags[]