# OMI_L3_OMHCHOd

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `OMI_L3_OMHCHOd` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime_start | double | {time} | [seconds since 2000-01-01] | start time of the grid
datetime_stop | double | {time} | [seconds since 2000-01-01] | end time of the grid
latitude | double | {latitude} | [degree_north] | latitude of the grid cell mid-point (WGS84)
longitude | double | {longitude} | [degree_east] | longitude of the grid cell mid-point (WGS84)
HCHO_column_number_density | double | {time, latitude, longitude} | [molecules/cm^2] | HCHO column number density
HCHO_column_number_density_uncertainty | double | {time, latitude, longitude} | [molecules/cm^2] | Uncertainty of the HCHO column number density.
index | int32 | {time} |  | zero-based index of the sample within the source product

## Mapping description

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

field name | mapping description
--- | ---
datetime_start | path | /@RangeBeginningDate
datetime_stop | path | /@RangeEndingDate
latitude | path | /@RangeEndingDate
description | a uniformly increasing sequence on the interval (-90, 90)
longitude | path | /@RangeEndingDate
description | a uniformly increasing sequence on the interval (-180, 180)
HCHO_column_number_density | path | /key_science_data/column_amount[]
HCHO_column_number_density_uncertainty | path | /key_science_data/column_uncertainty[]