# OCO_OCO2_LtCO2

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `OCO_OCO2_LtCO2` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime | double | {time} | [seconds since 1970-01-01] | time of the measurement
latitude | double | {time} | [degree_north] | center latitude of the measurement
longitude | double | {time} | [degree_east] | center longitude of the measurement
latitude_bounds | double | {time, 4} | [degree_north] | corner latitudes of the measurement
longitude_bounds | double | {time, 4} | [degree_east] | corner longitudes of the measurement
surface_altitude | double | {time} | [m] | surface altitude
surface_pressure | double | {time} | [hPa] | retrieved surface pressure
pressure | double | {time, vertical} | [hPa] | pressure levels
sensor_azimuth_angle | double | {time} | [degree] | sensor azimuth angle
sensor_zenith_angle | double | {time} | [degree] | sensor zenith angle
solar_azimuth_angle | double | {time} | [degree] | solar azimuth angle
solar_zenith_angle | double | {time} | [degree] | solar zenith angle
CO2_column_volume_mixing_ratio_dry_air | double | {time} | [ppmv] | Column-averaged dry-air mole fraction of CO2 (includes bias correction)
CO2_column_volume_mixing_ratio_dry_air_uncertainty | double | {time} | [ppmv] | XCO2 posterior error
CO2_column_volume_mixing_ratio_dry_air_validity | int8 | {time} |  | XCO2 simple quality bitflag
CO2_column_volume_mixing_ratio_dry_air_apriori | double | {time} | [ppmv] | XCO2 a-priori
CO2_column_volume_mixing_ratio_dry_avk | double | {time, vertical} | [ppmv/ppmv] | XCO2 column averaging kernel
CO2_volume_mixing_ratio_dry_air_apriori | double | {time, vertical} | [ppmv] | CO2 a-priori profile
validity | int8 | {time} |  | XCO2 quality flag
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 | path | /time[]
latitude | path | /latitude[]
longitude | path | /longitude[]
latitude_bounds | path | /vertex_latitude[]
longitude_bounds | path | /vertex_longitude[]
surface_altitude | path | /Sounding/altitude[]
surface_pressure | path | /Retrieval/psurf[]
pressure | path | /pressure_levels[]
description | the vertical grid is inverted to make it ascending
sensor_azimuth_angle | path | /Sounding/sensor_azimuth_angle[]
sensor_zenith_angle | path | /sensor_zenith_angle[]
solar_azimuth_angle | path | /Sounding/solar_azimuth_angle[]
solar_zenith_angle | path | /solar_zenith_angle[]
CO2_column_volume_mixing_ratio_dry_air | path | /xco2[]
CO2_column_volume_mixing_ratio_dry_air_uncertainty | path | /xco2_uncertainty[]
CO2_column_volume_mixing_ratio_dry_air_validity | available | optional
condition | version>9
path | /xco2_qf_simple_bitflag[]
CO2_column_volume_mixing_ratio_dry_air_apriori | path | /xco2_apriori[]
CO2_column_volume_mixing_ratio_dry_avk | path | /xco2_averaging_kernel[]
description | the vertical grid is inverted to make it ascending
CO2_volume_mixing_ratio_dry_air_apriori | path | /co2_profile_apriori[]
description | the vertical grid is inverted to make it ascending
validity | path | /xco2_quality_flag[]