# S4-L2-SO2

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `S4-L2-SO2` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime | double | {time} | [seconds since 2000-01-01] | time of the measurement
datetime_length | double |  | [s] | measurement duration
latitude | float | {time} | [degree_north] | pixel center latitude
longitude | float | {time} | [degree_east] | pixel center longitude
latitude_bounds | float | {time, 4} | [degree_north] | latitudes of pixel boundary
longitude_bounds | float | {time, 4} | [degree_north] | latitudes of pixel boundary
validity | int8 | {time} |  | continuous quality descriptor, varying between 0 (no data) and 100 (full quality data)
SO2_column_number_density | float | {time} | [mol/m^2] | sulphur dioxide column density
SO2_column_number_density_uncertainty_random | float | {time} | [mol/m^2] | random error of sulphur dioxide column density
SO2_column_number_density_uncertainty_systematic | float | {time} | [mol/m^2] | systematic error of sulphur dioxide column density
SO2_column_number_density_amf | float | {time} | [] | total air mass factor
SO2_column_number_density_amf_uncertainty_random | float | {time} | [] | random error of total air mass factor
SO2_column_number_density_amf_uncertainty_systematic | float | {time} | [] | systematic error of total air mass factor
index | int32 | {time} |  | zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for `S4-L2-SO2` products.

option name | legal values | description
--- | --- | ---
so2_column | 1km, 7km, 15km | whether to ingest the anothropogenic SO2 column at the PBL (default), the SO2 column from the 1km box profile (so2_column=1km), from the 7km box profile (so2_column=7km), or from the 15km box profile (so2_column=15km)

## Mapping description

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

field name | mapping description
--- | ---
datetime | path | /@time_reference_days_since_1950, /PRODUCT/delta_time[]
description | time reference converted from days since 1950-01-01 to seconds since 2020-01-01 (using 86400 seconds per day) and delta_time added
datetime_length | path | /PRODUCT/delta_time[]
description | delta_time[num_ground_pixels] - delta_time[0]
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[]
validity | path | /PRODUCT/qa_value
SO2_column_number_density | condition | so2_column unset
path | /PRODUCT/sulfur_dioxide_total_column_polluted[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_1km[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_7km[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_15km[]
SO2_column_number_density_uncertainty_random | condition | so2_column unset
path | /PRODUCT/sulfur_dioxide_total_column_polluted_precision[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_1km_precision[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_7km_precision[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_15km_precision[]
SO2_column_number_density_uncertainty_systematic | condition | so2_column unset
path | /PRODUCT/sulfur_dioxide_total_column_polluted_trueness[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_1km_trueness[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_7km_trueness[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_column_15km_trueness[]
SO2_column_number_density_amf | condition | so2_column unset
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_polluted[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_1km[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_7km[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_15km[]
SO2_column_number_density_amf_uncertainty_random | condition | so2_column unset
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_polluted_precision[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_1km_precision[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_7km_precision[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_15km_precision[]
SO2_column_number_density_amf_uncertainty_systematic | condition | so2_column unset
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_polluted_trueness[]
condition | so2_column=1km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_1km_trueness[]
condition | so2_column=7km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_7km_trueness[]
condition | so2_column=15km
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/sulfur_dioxide_total_air_mass_factor_15km_trueness[]