# S4-L2-AUI

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `S4-L2-AUI` 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)
absorbing_aerosol_index | float | {time} | [] | aerosol index
absorbing_aerosol_index_uncertainty | float | {time} | [] | uncertainty of the aerosol index
scene_albedo | float | {time} | [] | scene albedo
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-AUI` products.

option name | legal values | description
--- | --- | ---
wavelength_ratio | 354_388nm, 340_380nm | ingest aerosol index retrieved at wavelengths 354/388 nm (default) or 354/388 nm (wavelength_ratio=340_380nm)

## 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
absorbing_aerosol_index | condition | wavelength_ratio=354_388nm or wavelength_ratio unset
path | /PRODUCT/aerosol_index_354_388
condition | wavelength_ratio=340_380nm
path | /PRODUCT/aerosol_index_340_380
absorbing_aerosol_index_uncertainty | condition | wavelength_ratio=354_388nm or wavelength_ratio unset
path | /PRODUCT/aerosol_index_354_388_precision
condition | wavelength_ratio=340_380nm
path | /PRODUCT/aerosol_index_340_380_precision
scene_albedo | condition | wavelength_ratio=354_388nm or wavelength_ratio unset
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/scene_albedo_388[]
condition | wavelength_ratio=340_380nm
path | /PRODUCT/SUPPORT_DATA/DETAILED_RESULTS/scene_albedo_380[]