# MLS_L2_SO2

## Variables

The table below lists the variables that are present in the HARP product that results from an ingestion of `MLS_L2_SO2` data.

field name | type | dimensions | unit | description
--- | --- | --- | --- | ---
datetime | double | {time} | [seconds since 2000-01-01] | time of the measurement
longitude | double | {time} | [degree_east] | tangent longitude
latitude | double | {time} | [degree_north] | tangent latitude
pressure | double | {vertical} | [hPa] | pressure per profile level
SO2_volume_mixing_ratio | double | {time, vertical} | [ppv] | SO2 volume mixing ratio
SO2_volume_mixing_ratio_uncertainty | double | {time, vertical} | [ppv] | uncertainty of the SO2 volume mixing ratio
SO2_volume_mixing_ratio_validity | int32 | {time, vertical} |  | quality flag for the SO2 volume mixing ratio
index | int32 | {time} |  | zero-based index of the sample within the source product

## Mapping description

Bits 4 to 9 and 11 to 14 in the quality flag denote a specific error condition while bits 0 to 2 denote the severity (bit 0 error, bit 1 warning, bit 2 comment).

Bits 4 to 9 denote the MLS status (bit 4 HICLOUD, bit 5 LOWCLOUD, bit 6 NO_APRIORI_T, bit 7 NUM_ERROR, bit 8 TOO_FEW_RAD, bit 9 GLOB_FAILURE).

Bits 11 to 14 denote specific checks as specified in the EOS MLS data quality document (the pressure range, quality and convergence thresholds come from table 1.1.1 in issue 4.x-4.0 of that document): Bit 11 denotes pressure out of range, bit 12 denotes quality below threshold, bit 13 denotes convergence above threshold and bit 14 denotes a negative precision. Also, if any of the bits 11 to 14 is set, bit 0 is automatically set.

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

field name | mapping description
--- | ---
datetime | path | /HDFEOS/SWATHS/SO2/Geolocation_Fields/Time[]
description | the time converted from TAI93 to seconds since 2000-01-01T00:00:00
longitude | path | /HDFEOS/SWATHS/SO2/Geolocation_Fields/Longitude[]
latitude | path | /HDFEOS/SWATHS/SO2/Geolocation_Fields/Latitude[]
pressure | path | /HDFEOS/SWATHS/SO2/Geolocation_Fields/Pressure[]
SO2_volume_mixing_ratio | path | /HDFEOS/SWATHS/SO2/Data_Fields/L2gpValue[]
SO2_volume_mixing_ratio_uncertainty | path | /HDFEOS/SWATHS/SO2/Data_Fields/L2gpPrecision[]
SO2_volume_mixing_ratio_validity | path | /HDFEOS/SWATHS/SO2/Data_Fields/Status[], /HDFEOS/SWATHS/SO2/Data_Fields/Quality[], /HDFEOS/SWATHS/SO2/Data_Fields/Convergence[], /HDFEOS/SWATHS/SO2/Data_Fields/L2gpPrecision[], /HDFEOS/SWATHS/SO2/Geolocation_Fields/Pressure[]
description | see generic mapping description