# SCIAMACHY_L2_NADIR_IR2_N2O

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of SCIAMACHY_L2_NADIR_IR2_N2O data.

field name

type

dimensions

unit

description

datetime_start

double

{time}

[seconds since 2000-01-01]

measurement start time

datetime_length

double

{time}

[s]

measurement integration time

orbit_index

int32

absolute orbit number

latitude

double

{time}

[degree_north]

center latitude for each nadir pixel

longitude

double

{time}

[degree_east]

center longitude for each nadir pixel

latitude_bounds

double

{time, 4}

[degree_north]

corner latitudes for each nadir pixel

longitude_bounds

double

{time, 4}

[degree_east]

corner longitudes for each nadir pixel

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_direction_type

int8

{time}

scan direction for each measurement; enumeration values: forward (0), backward (1), mixed (2)

N2O_column_number_density

double

{time}

[molec/cm^2]

N2O vertical column density

N2O_column_number_density_uncertainty

double

{time}

[molec/cm^2]

error on the N2O vertical column density

N2O_column_number_density_validity

int32

{time}

flag describing the N2O vertical column density

cloud_fraction

double

{time}

[]

average cloud fraction of footprint

index

int32

{time}

zero-based index of the sample within the source product

## Ingestion options

The table below lists the available ingestion options for SCIAMACHY_L2 products.

option name

legal values

description

dataset

nad_uv0_o3, nad_uv1_no2, nad_uv3_bro, nad_uv4_h2co, nad_uv5_so2, nad_uv6_oclo, nad_uv7_so2, nad_uv8_h2o, nad_uv9_chocho, nad_ir0_h2o, nad_ir1_ch4, nad_ir2_n2o, nad_ir3_co, nad_ir4_co2, lim_uv0_o3, lim_uv1_no2, lim_uv3_bro, clouds_aerosol

the dataset of the L2 product to ingest; each dataset is a combination of nadir/limb choice, retrieval window, and main quantity; option values are ‘nad_uv0_o3’ (default), ‘nad_uv1_no2’, ‘nad_uv3_bro’, ‘nad_uv4_h2co’, ‘nad_uv5_so2’, ‘nad_uv6_oclo’, ‘nad_uv7_so2’, ‘nad_uv8_h2o’, ‘nad_uv9_chocho’, ‘nad_ir0_h2o’, ‘nad_ir1_ch4’, ‘nad_ir2_n2o’, ‘nad_ir3_co’, ‘nad_ir4_co2’, ‘lim_uv0_o3’, ‘lim_uv1_no2’, ‘lim_uv3_bro’, ‘clouds_aerosol’

This definition is only applicable when: dataset=nad_ir2_n2o

## Mapping description

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

field name

mapping description

datetime_start

path

/nad_ir2_n2o[]/dsr_time

datetime_length

path

/nad_ir2_n2o[]/integr_time

orbit_index

path

/mph/abs_orbit

latitude

condition

No co-adding needed

path

/geolocation_nadir[]/cen_coor_nad/latitude

description

center latitude for each nadir pixel

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

the latitude of the geographic average of cor_coor_nad[2] and cor_coor_nad[3] of the N/2-th pixel

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/cen_coor_nad, /geolocation_nadir[]/cor_coor_nad[]

description

the latitude of the geographic average of 1: the geographic average of cor_coor_nad[2] and cor_coor_nad[3] of the second pixel and 2: cen_coor_nad of the N-th pixel

longitude

condition

No co-adding needed

path

/geolocation_nadir[]/cen_coor_nad/longitude

description

center longitude for each nadir pixel

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

the longitude of the geographic average of cor_coor_nad[2] and cor_coor_nad[3] of the N/2-th pixel

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/cen_coor_nad, /geolocation_nadir[]/cor_coor_nad[]

description

the longitude of the geographic average of 1: the geographic average of cor_coor_nad[2] and cor_coor_nad[3] of the second pixel and 2: cen_coor_nad of the N-th pixel

latitude_bounds

condition

No co-adding needed

path

/geolocation_nadir[]/cor_coor_nad[]/latitude

description

corners are rearranged in the following way: 0,2,3,1

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

cor_coor_nad[0] and cor_coor_nad[1] are taken from the first pixel and cor_coor_nad[2] and cor_coor_nad[3] are taken from the N-th pixel; corners are rearranged in the following way: 0,2,3,1

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

cor_coor_nad[0] is taken from the first pixel, cor_coor_nad[2] is taken from the fourth pixel, cor_coor_nad[1] is taken from cor_coor_nad[3] of the N-th pixel, and cor_coor_nad[3] is taken from cor_coor_nad[1] from the N-th pixel; corners are rearranged in the following way: 0,2,3,1

longitude_bounds

condition

No co-adding needed

path

/geolocation_nadir[]/cor_coor_nad[]/longitude

description

corners are rearranged in the following way: 0,2,3,1

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

cor_coor_nad[0] and cor_coor_nad[1] are taken from the first pixel and cor_coor_nad[2] and cor_coor_nad[3] are taken from the N-th pixel; corners are rearranged in the following way: 0,2,3,1

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/cor_coor_nad[]

description

cor_coor_nad[0] is taken from the first pixel, cor_coor_nad[2] is taken from the fourth pixel, cor_coor_nad[1] is taken from cor_coor_nad[3] of the N-th pixel, and cor_coor_nad[3] is taken from cor_coor_nad[1] from the N-th pixel; corners are rearranged in the following way: 0,2,3,1

solar_zenith_angle

condition

No co-adding needed

path

/geolocation_nadir[]/sol_zen_angle_toa[1]

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/sol_zen_angle_toa[2]

description

the value at end of integration time of the N/2-th geolocation

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/sol_zen_angle_toa[1], /geolocation_nadir[]/sol_zen_angle_toa[2]

description

the average of the value at end of integration time of the second record and the value at middle of integration time of the N-th record

viewing_zenith_angle

condition

No co-adding needed

path

/geolocation_nadir[]/los_zen_angle_toa[1]

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/los_zen_angle_toa[2]

description

the value at end of integration time of the N/2-th geolocation

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/los_zen_angle_toa[1], /geolocation_nadir[]/los_zen_angle_toa[2]

description

the average of the value at end of integration time of the second record and the value at middle of integration time of the N-th record

relative_azimuth_angle

condition

No co-adding needed

path

/geolocation_nadir[]/rel_azi_angle_toa[1]

condition

Co-adding needed and all N geolocations are within a single scan (N is not divisible by 5)

path

/geolocation_nadir[]/rel_azi_angle_toa[2]

description

the value at end of integration time of the N/2-th geolocation

condition

Co-adding needed of both forward and backward scan pixels (N is divisible by 5)

path

/geolocation_nadir[]/rel_azi_angle_toa[1], /geolocation_nadir[]/rel_azi_angle_toa[2]

description

the average of the value at end of integration time of the second record and the value at middle of integration time of the N-th record

scan_direction_type

path

/geolocation_nadir[]/corner_coord[], /geolocation_nadir[]/dsr_time

description

When the integration time is higher than 1s we are dealing with a mixed (2) pixel, otherwise the scan direction is based on the corner coordinates of the first ground pixel of the measurement. The first geolocation pixel is a backscan (1) pixel if the inproduct of the unit vector of the third corner with the outproduct of the unit vector of the first corner and the unit vector of the second corner is negative (otherwise it is part of a forward (0) scan)

N2O_column_number_density

path

/nad_ir2_n2o[]/vcd[0]

N2O_column_number_density_uncertainty

path

/nad_ir2_n2o[]/vcd_err[0], /nad_ir2_n2o[]/vcd[0]

description

relative error is converted to absolute error by multiplying with measured value

N2O_column_number_density_validity

path

/nad_ir2_n2o[]/flag_vcd_flags

cloud_fraction

path

/clouds_aerosol[]/cl_frac

description

in case of co-adding, the average of all values within the integration time is taken