# ECA_ATL_NOM_1B

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `ECA_ATL_NOM_1B` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime | double | {time} | [seconds since 2000-01-01] | UTC time
latitude | double | {time, vertical} | [degree_north] | latitude
longitude | double | {time, vertical} | [degree_east] | longitude
altitude | float | {time, vertical} | [m] | altitude
orbit_index | int32 |  |  | absolute orbit number
backscatter_coefficient | float | {time, vertical} | [1/m/sr] | attenuated backscatter
backscatter_coefficient_uncertainty | float | {time, vertical} | [1/m/sr] | attenuated backscatter
index | int32 | {time} |  | zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for `ECA_ATL_NOM_1B` products.

option name | legal values | description
--- | --- | ---
data | rayleigh, mie, crosspolar | the type of backscatter profile to ingest; option values are ‘rayleigh’ (default), ‘mie’, ‘crosspolar’

## Mapping description

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

field name | mapping description
--- | ---
datetime | path | /ScienceData/time
latitude | path | /ScienceData/sample_latitude
description | the vertical grid is inverted to make it ascending
longitude | path | /ScienceData/sample_longitude
description | the vertical grid is inverted to make it ascending
altitude | path | /ScienceData/sample_altitude
description | the vertical grid is inverted to make it ascending
orbit_index | path | /HeaderData/VariableProductHeader/MainProductHeader/orbitNumber
backscatter_coefficient | condition | data=rayleigh or data unset
path | /ScienceData/rayleigh_attenuated_backscatter
description | the vertical grid is inverted to make it ascending
condition | data=mie
path | /ScienceData/mie_attenuated_backscatter
description | the vertical grid is inverted to make it ascending
condition | data=crosspolar
path | /ScienceData/crosspolar_attenuated_backscatter
description | the vertical grid is inverted to make it ascending
backscatter_coefficient_uncertainty | condition | data=rayleigh or data unset
path | /ScienceData/rayleigh_attenuated_backscatter_total_error
description | the vertical grid is inverted to make it ascending
condition | data=mie
path | /ScienceData/mie_attenuated_backscatter_total_error
description | the vertical grid is inverted to make it ascending
condition | data=crosspolar
path | /ScienceData/crosspolar_attenuated_backscatter_total_error
description | the vertical grid is inverted to make it ascending