# GOME_L2

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `GOME_L2` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime_stop | double | {time} | [seconds since 2000-01-01] | time of the measurement at end of integration time
datetime_length | double | {time} | [s] | measurement integration time
orbit_index | int32 |  |  | absolute orbit number
latitude | double | {time} | [degree_north] | tangent latitude of the measurement
longitude | double | {time} | [degree_east] | tangent longitude of the measurement
latitude_bounds | double | {time, 4} | [degree_north] | corner latitudes for the ground pixel of the measurement
longitude_bounds | double | {time, 4} | [degree_east] | corner longitudes for the ground pixel of the measurement
O3_column_number_density | double | {time} | [molec/cm^2] | ozone total column
O3_column_number_density_uncertainty | double | {time} | [molec/cm^2] | error on the ozone total column
NO2_column_number_density | double | {time} | [molec/cm^2] | NO2 total column
NO2_column_number_density_uncertainty | double | {time} | [molec/cm^2] | error on the NO2 total column
cloud_fraction | double | {time} | [] | cloud fraction
cloud_fraction_uncertainty | double | {time} | [] | cloud fraction error
cloud_top_height | double | {time} | [km] | cloud top height
cloud_top_height_uncertainty | double | {time} | [km] | cloud top height uncertainty
cloud_top_pressure | double | {time} | [hPa] | cloud top pressure
cloud_top_pressure_uncertainty | double | {time} | [hPa] | cloud top pressure uncertainty
cloud_top_albedo | double | {time} | [] | cloud top albedo
cloud_top_albedo_uncertainty | double | {time} | [] | cloud top albedo uncertainty
surface_pressure | double | {time} | [hPa] | surface pressure
surface_height | double | {time} | [km] | surface height
surface_albedo | double | {time} | [] | surface albedo
solar_zenith_angle | double | {time} | [degree] | solar zenith angle at top of atmosphere
viewing_zenith_angle | double | {time} | [degree] | line of sight zenith angle at top of atmosphere
relative_azimuth_angle | double | {time} | [degree] | relative azimuth angle at top of atmosphere
scan_subindex | int8 | {time} |  | relative index (0-3) of this measurement within a scan (forward + backward)
scan_direction_type | int8 | {time} |  | scan direction for each measurement; enumeration values: forward (0), backward (1)
index | int32 | {time} |  | zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for `GOME_L2` products.

option name | legal values | description
--- | --- | ---
ozone | vcd1 | the fitting window choice for ozone to ingest; either window 0 (default) or window 1 (ozone=vcd1)

## Mapping description

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

field name | mapping description
--- | ---
datetime_stop | path | /ddr[]/glr/datetime
datetime_length | description | set to a fixed value of 1.5s for all pixels
orbit_index | path | /pir/start_orbit
latitude | path | /ddr[]/glr/corners[4]/lat
longitude | path | /ddr[]/glr/corners[4]/lon
description | each longitude will be transformed from a value in the range 0 - 360 to a value in the range -180 - 180
latitude_bounds | path | /ddr[]/glr/corners[0:3]/lat
description | the corners are rearranged in the following way: 1,3,2,0
longitude_bounds | path | /ddr[]/glr/corners[0:3]/lon
description | the corners are rearranged in the following way: 1,3,2,0
O3_column_number_density | condition | ozone unset
path | /ddr[]/irr/vcd[0]/total
condition | ozone=vcd1
path | /ddr[]/irr/vcd[1]/total
O3_column_number_density_uncertainty | condition | ozone unset
path | /ddr[]/irr/vcd[0]/total, /ddr[]/irr/vcd[0]/error
description | relative error is converted to absolute error by multiplying with measured value
condition | ozone=vcd1
path | /ddr[]/irr/vcd[1]/total, /ddr[]/irr/vcd[1]/error
description | relative error is converted to absolute error by multiplying with measured value
NO2_column_number_density | path | /ddr[]/irr/vcd[2]/total
NO2_column_number_density_uncertainty | path | /ddr[]/irr/vcd[2]/total, /ddr[]/irr/vcd[2]/error
description | relative error is converted to absolute error by multiplying with measured value
cloud_fraction | condition | version=1
path | /ddr[]/irr/icfa/frac
condition | version>1
path | /ddr[]/irr/ocra/cloud_frac
cloud_fraction_uncertainty | condition | version=1
path | /ddr[]/irr/icfa/frac, /ddr[]/irr/icfa/err_frac
description | relative error is converted to absolute error by multiplying with measured value
condition | version>1
path | /ddr[]/irr/ocra/cloud_frac, /ddr[]/irr/ocra/cloud_frac_error
description | relative error is converted to absolute error by multiplying with measured value
cloud_top_height | available | optional
condition | version>1
path | /ddr[]/irr/rocinn/height
cloud_top_height_uncertainty | available | optional
condition | version>1
path | /ddr[]/irr/rocinn/height, /ddr[]/irr/rocinn/height_error
description | relative error is converted to absolute error by multiplying with measured value
cloud_top_pressure | condition | version=1
path | /ddr[]/irr/icfa/press
condition | version>1
path | /ddr[]/irr/rocinn/pressure
cloud_top_pressure_uncertainty | condition | version=1
path | /ddr[]/irr/icfa/press, /ddr[]/irr/icfa/err_press
description | relative error is converted to absolute error by multiplying with measured value
condition | version>1
path | /ddr[]/irr/rocinn/pressure, /ddr[]/irr/rocinn/pressure_error
description | relative error is converted to absolute error by multiplying with measured value
cloud_top_albedo | available | optional
condition | version>1
path | /ddr[]/irr/rocinn/albedo
cloud_top_albedo_uncertainty | available | optional
condition | version>1
path | /ddr[]/irr/rocinn/albedo, /ddr[]/irr/rocinn/albedo_error
description | relative error is converted to absolute error by multiplying with measured value
surface_pressure | condition | version=1
path | /ddr[]/irr/icfa/surf_press
condition | version>1
path | /ddr[]/irr/surface_pressure
surface_height | available | optional
condition | version>1
path | /ddr[]/irr/surface_height
surface_albedo | available | optional
condition | version>1
path | /ddr[]/irr/surface_albedo
solar_zenith_angle | path | /ddr[]/glr/sza_toa[1]
viewing_zenith_angle | path | /ddr[]/glr/line_sight_toa[1]
relative_azimuth_angle | path | /ddr[]/glr/rel_azi_toa[1]
scan_subindex | path | /ddr[]/glr/subset_counter
description | relative index (0-3) of this measurement within a scan (forward + backward)
scan_direction_type | path | /ddr[]/glr/subset_counter
description | the scan direction is based on the subset_counter of the measurement; 0-2: forward (0), 3: backward (1)