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CALIPSO: Data User's Guide - Data Product Description - Lidar Level 3 Stratospheric Aerosol Profile Monthly Product Version 1.00


CALIPSO HOMECALIPSO User’s Guide HOMEData Products Descriptions → Lidar Level 3 Stratospheric Aerosol Profile Monthly Product

Introduction

The Lidar Level 3 stratospheric aerosol profile product reports global distributions of 532 nm total attenuated backscatter, particulate backscatter, extinction, attenuated scattering ratios, and stratospheric aerosol optical depths on a uniform spatial grid. All level 3 parameters are derived from the CALIPSO version 4 level 1 and level 2 5 km merged layer and version 1.x level 2 polar stratospheric cloud data products, with a temporal averaging of one month.

Resolution and Coverage

Table 1: The spatial coverage and resolution of L3 stratospheric aerosol profile product.

Spatial Coverage Spatial Resolution
Horizontal:
  • 360° longitude (180° W to 180° E)
  • 170° latitude (85° S to 85° N)
  • 20° longitude by 5° latitude
    Vertical:
  • 8.2 km to 36.2 km altitude
  • 900 m vertical resolution

    Reference

    Young, S. A. and Vaughan, M. A., “The retrieval of profiles of particulate extinction from Cloud - Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) data: Algorithm description”, J. Atmos. Ocean. Tech., 26, 1105-1119, doi:10.1175/2008JTECHA1221, 2009.

    Data Descriptions

    In the text below we provide brief descriptions of individual data fields reported in the CALIPSO L3 stratospheric aerosol profile product. Where appropriate, we also provide an assessment of the quality and accuracy of the data in the current release. The data descriptions are grouped into several major categories, as follows:

    Additionally all the science data sets (SDSs) are listed in the table to the right, click on the SDS name to go directly to the description.

    Science Data Set (SDS)
    Longitude_Midpoint
    Latitude_Midpoint
    Altitude_Midpoint
    Tropopause_Height_Mean
    Potential_Temperature_Mean
    Number_of_Granules
    Calibration_Coefficient_Mean_532
    Calibration_Coefficient_Standard_Deviation_532
    Samples_Calibration_Coefficient_532
    Stratospheric_Optical_Depth_Background
    Stratospheric_Optical_Depth_Uncertainty_Background
    Total_Attenuated_Backscatter_Background
    Total_Attenuated_Backscatter_Standard_Deviation_Background
    Samples_Accepted_Background
    Samples_Rejected_Background
    Molecular_Backscatter_Background
    Molecular_Backscatter_Standard_Deviation_Background
    Ozone_Absorption_Coefficient_Background
    Ozone_Absorption_Coefficient_Standard_Deviation_Background
    Attenuated_Scattering_Ratio_Background
    Attenuated_Scattering_Ratio_Uncertainty_Background
    Particulate_Backscatter_Background
    Particulate_Backscatter_Uncertainty_Background
    Extinction_Coefficient_Background
    Extinction_Coefficient_Uncertainty_Background
    Stratospheric_Optical_Depth
    Stratospheric_Optical_Depth_Uncertainty
    Total_Attenuated_Backscatter
    Total_Attenuated_Backscatter_Standard_Deviation
    Samples_Accepted
    Samples_Rejected
    Molecular_Backscatter
    Molecular_Backscatter_Standard_Deviation
    Ozone_Absorption_Coefficient
    Ozone_Absorption_Coefficient_Standard_Deviation
    Attenuated_Scattering_Ratio
    Attenuated_Scattering_Ratio_Uncertainty
    Particulate_Backscatter
    Particulate_Backscatter_Uncertainty
    Extinction_Coefficient
    Extinction_Coefficient_Uncertainty

    In the following we provide brief descriptions of individual data fields reported in the stratospheric aerosol product. The primary outputs are reported in terms of 1) Background component and 2) All aerosol component. For the Background component, all features identified by the level 2 algorithms have been removed. For All aerosol, aerosol layers are retained while clouds and polar stratospheric clouds are removed. See the detailed data quality summary for more details of this procedure.



    Spatial Coordinates

    Longitude_Midpoint (1-D array)
    Units: degree (°)
    Format: Float_32
    Valid range: -180.0...180.0
    Definition: Longitude at the latitude/longitude/altitude grid cell midpoint.

    Latitude_Midpoint (1-D array)
    Units: degree (°)
    Format: Float_32
    Valid range: -85.0...85.0
    Definition: Latitude at the latitude/longitude/altitude grid cell midpoint.

    Altitude_Midpoint (1-D array)
    Units: kilometer (km)
    Format: Float_32
    Valid range: 8.2...36.2
    Definition: Altitude at the latitude/longitude/altitude grid cell midpoint.

    Meteorological Context

    Tropopopause_Height_Mean (external, 2-D array)
    Units: kilometer (km)
    Format: Float_32
    Fill value: -9999.0000
    Valid range: 5.0...18.0
    Definition: The mean tropopause height above local mean sea level within a latitude/ longitude grid cell. This is derived from the MERRA-2 reanalyses.

    Potential_Temperature_Mean (external, 3-D array)
    Units: Kelvin (K)
    Format: Float_32
    Fill value: -9999.0000
    Valid range: 300.0...1,250.0
    Definition: Mean potential temperature within a latitude/longitude/altitude grid cell, calculated from the MERRA-2 reanalyses.

    Overflight Parameters

    Number_of_Granules (2-D array)
    Units: NoUnits
    Format: Int_16
    Valid Range: 0...451
    Description: Number of granules passing through the latitude/ longitude grid cell which contribute.

    532 nm Calibration Parameters

    Calibration_Coefficient_Mean_532 (2-D array)
    Units: km3·sr·J-1·count
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 4.4E10...6.6E10
    Description: Mean 532 nm calibration coefficient within a latitude/longitude grid cell, calculated using all the contributing profiles falling within the grid cell.

    Calibration_Coefficient_Standard_Deviation_532 (2-D array)
    Units: km3·sr·J-1·count
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...5.7E8
    Description: Standard deviation of 532 nm nighttime calibration coefficients within a latitude/longitude grid cell, calculated using all the contributing profiles falling within the grid cell.

    Samples_Calibration_Coefficient_532 (2-D array)
    Units: NoUnits
    Format: Int_32
    Fill Value: -9999
    Valid Range: 0...8,000
    Description: Number of samples used for calculating the calibration coefficient statistics within a latitude/longitude grid cell.

    532 nm Background Component

    Stratospheric_Optical_Depth_Background (2-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -0.05...0.06
    Description: Optical depth in the background component, within a latitude/longitude grid cell, calculated by integrating the mean extinction coefficient profile from the uppermost altitude bin (36 km) down to the altitude of the mean tropopause in that grid cell or to the last point above the tropopause if the extinction profile does not extend all the way to the tropopause.

    Stratospheric_Optical_Depth_Uncertainty_Background (2-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...0.02
    Description: The uncertainty in the stratospheric optical depth in the background component, within a latitude/longitude grid cell.

    Total_Attenuated_Backscatter_Background (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...5.3E-4
    Description: Mean of the calibrated total attenuated backscatter within a latitude/longitude/altitude grid cell for the background component. This is the primary input into the extinction engine, along with the gridded molecular backscatter and the ozone absorption coefficient. Note that we exclude all measurements over the South Atlantic Anomaly (SAA) region because of noise issues. For the background mode, all layers detected by the CALIOP level 2 algorithm are removed, which includes aerosol, cloud and polar stratospheric clouds (PSC).

    Total_Attenuated_Backscatter_Standard_Deviation_Background (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.1E-5
    Description: Standard deviation of total attenuated backscatter within a latitude/longitude/altitude grid cell for the background component.

    Samples_Accepted_Background (3-D-array)
    Units: NoUnits
    Format: Int_32
    Fill Value: -9999
    Valid Range: 0...8,000
    Description: Number of samples within a latitude/longitude/altitude grid cell contributing to the gridded value of the total attenuated backscatter in the grid cell, for the background component. This is the number of samples that pass the quality filtering criteria.

    Samples_Rejected_Background (3-D array)
    Units: NoUnits
    Format: Int_32
    Fill Value: -9999
    Valid Range: 0...8,000
    Description: Number of samples within a latitude/longitude/altitude grid cell that have been rejected by the quality filtering scheme for the background component.

    Molecular_Backscatter_Background (External, 3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...5.3E-4
    Description: Mean of molecular backscatter within a latitude/longitude/altitude grid cell, for the background component, calculated from the MERRA-2 meteorological input data on molecular density given in CALIOP level 1B files and the theoretical value of the molecular backscatter cross section. The molecular data are gridded using the same number of profiles corresponding to the profiles accepted for gridding the primary input of total attenuated backscatter within a grid cell for the background component.

    Molecular_Backscatter_Standard_Deviation_Background (External, 3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.1E-5
    Description: Standard deviation of molecular backscatter within a latitude/longitude/altitude grid cell, calculated from the meteorological data, for the background component.

    Ozone_Absorption_Coefficient_Background (External, 3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...1.9E-3
    Description: Mean of the ozone absorption coefficient within a latitude/longitude/altitude grid cell, for the background component. As for the molecular backscatter, ozone absorption is also computed using the ozone density profiles from the MERRA-2 input data and is gridded using the same number of profiles corresponding to the accepted profiles of total backscatter within a grid cell in the background component.

    Ozone_Absorption_Coefficient_Standard_Deviation_Background (External, 3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...8.0E-5
    Description: Standard deviation of ozone absorption coefficient within a latitude/longitude/altitude grid cell, calculated from meteorological data, for the background component.

    Attenuated_Scattering_Ratio_Background (3-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.30...1.70
    Description: Attenuated scattering ratio is defined as the ratio of the measured attenuated backscatter coefficients and the attenuated backscatter coefficients calculated from the molecular model. This parameter provides the mean attenuated scattering ratio computed in a latitude/longitude/altitude grid cell for the background component.

    Attenuated_Scattering_Ratio_Uncertainty_Background (3-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.03...0.35
    Description: Uncertainties in attenuated scattering ratio calculated within a latitude/longitude/ altitude grid cell in the background component.

    Particulate_Backscatter_Background (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -1.1E-4...1.3E-4
    Description: Retrieved value of the particulate backscatter within a latitude/longitude/altitude grid cell for the background component.

    Particulate_Backscatter_Uncertainty_Background (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...4.5E-5
    Description: The uncertainties in particulate backscatter in the background component computed in a latitude/longitude/altitude grid cell.

    Extinction_Coefficient_Background (3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -5.4E-03...6.5E-3
    Description: The extinction coefficients in the background component in a latitude/longitude/altitude grid cell obtained from the retrieved particulate backscatter profiles and using the lidar ratio of 50 sr.

    Extinction_Coefficient_Uncertainty_Background (3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.6E-3
    Description: Uncertainties in the extinction coefficients in the background component, in a latitude/longitude/altitude grid cell, computed in the same way as the particulate backscatter uncertainties. This is the primary quality assurance metric for the extinction profiles.

    532 nm All Aerosol Component

    Stratospheric_Optical_Depth (2-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -0.02...2.00
    Description: Optical depth in the all aerosol component, within a latitude/longitude grid cell, calculated by integrating the mean extinction coefficient profile from the uppermost altitude bin (36 km) down to the altitude of the mean tropopause in that grid cell or to the last point above the tropopause if the extinction profile does not extend all the way to the tropopause.

    Figure 1. Spatial distribution of stratospheric aerosol optical depth in August 2017 from (left) the background component and (right) the all aerosol component. The signature of the smoke layers from the intense biomass burning in Canada during this month can be seen in the all aerosol component.


    Stratospheric_Optical_Depth_Uncertainty (2-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 2.4E-2...0.40
    Description: The uncertainty in the stratospheric optical depth in the all aerosol component, within a latitude/longitude grid cell.

    Total_Attenuated_Backscatter (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...6.3E-4
    Description: Mean of the calibrated total attenuated backscatter within a latitude/longitude/altitude grid cell for the all aerosol component. This is the primary input into the extinction engine, along with the gridded molecular backscatter and the ozone absorption coefficient. Note that we exclude all measurements over the South Atlantic Anomaly (SAA) region because of noise issues. For the all aerosol component, the clouds and PSCs are removed while the total backscatter from the aerosol layers are retained.

    Total_Attenuated_Backscatter_Standard_Deviation (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.2E-4
    Description: Standard deviation of total attenuated backscatter within a latitude/longitude/altitude grid cell for the all aerosol component.

    Figure 2. Global distribution of the number of accepted and rejected samples at 18 km for July 2015 for the all aerosol component. Data over the SAA region (in white) are not used. Numbers of both accepted and rejected samples are highest over Antarctica because of the orbital geometry.


    Samples_Accepted (3-D-array)
    Units: NoUnits
    Format: Int_32
    Fill Value: -9999
    Valid Range: 0...8,000
    Description: Number of samples within a latitude/longitude/altitude grid cell contributing to the gridded value of the total attenuated backscatter in the grid cell, for the all aerosol component. This is the number of samples that pass the quality filtering criteria.

    Samples_Rejected (3-D array)
    Units: NoUnits
    Format: Int_32
    Fill Value: -9999
    Valid Range: 0...8,000
    Description: Number of samples within a latitude/longitude/altitude grid cell that have been rejected by the quality filtering scheme for the all aerosol component.

    Molecular_Backscatter (External, 3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...5.3E-4
    Description: Mean of molecular backscatter within a latitude/longitude/altitude grid cell, for the all aerosol component, calculated from the MERRA-2 meteorological input data on molecular density given in CALIOP level 1B files and the theoretical value of the molecular backscatter cross section. The molecular data are gridded using the same number of profiles corresponding to the profiles accepted for gridding the primary input of total attenuated backscatter within a grid cell for the all aerosol component.

    Molecular_Backscatter_Standard_Deviation (External, 3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.1E-5
    Description: Standard deviation of molecular backscatter within a latitude/longitude/altitude grid cell, calculated from the meteorological data, for the all aerosol component.

    Ozone_Absorption_Coefficient (External, 3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...1.9E-3
    Description: Mean of the ozone absorption coefficient within a latitude/longitude/altitude grid cell, for the all aerosol component. As for the molecular backscatter, ozone absorption is also computed using the ozone density profiles from the MERRA-2 input data and is gridded using the same number of profiles corresponding to the accepted profiles of total backscatter within a grid cell in the all aerosol component.

    Ozone_Absorption_Coefficient_Standard_Deviation (External, 3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...9.5E-5
    Description: Standard deviation of ozone absorption coefficient within a latitude/longitude/altitude grid cell, calculated from meteorological data, for the all aerosol component.

    Attenuated_Scattering_Ratio (3-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.60...25.00
    Description: Attenuated scattering ratio is defined as the ratio of the measured attenuated backscatter coefficients and the attenuated backscatter coefficients calculated from the molecular model. This parameter provides the mean attenuated scattering ratio computed in a latitude/longitude/altitude grid cell for the all aerosol component.

    Attenuated_Scattering_Ratio_Uncertainty (3-D array)
    Units: NoUnits
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.03...5.6
    Description: Uncertainties in attenuated scattering ratio calculated within a latitude/longitude/altitude grid cell in the all aerosol component.

    Particulate_Backscatter (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -6.2E-5...0.15
    Description: Retrieved value of the particulate backscatter within a latitude/longitude/altitude grid cell for the all aerosol component.

    Particulate_Backscatter_Uncertainty (3-D array)
    Units: km-1·sr-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...2.1E-2
    Description: The uncertainties in particulate backscatter in the all aerosol component computed in a latitude/longitude/altitude grid cell.

    Extinction_Coefficient (3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: -3.2E-3...7.5
    Description: The extinction coefficients in the all aerosol component in a latitude/longitude/altitude grid cell obtained from the retrieved particulate backscatter profiles and using the lidar ratio of 50 sr.

    Extinction_Coefficient_Uncertainty (3-D array)
    Units: km-1
    Format: Float_32
    Fill Value: -9999.0000
    Valid Range: 0.0...1.56
    Description: Uncertainties in the extinction coefficients in the all aerosol component, in a latitude/longitude/altitude grid cell, computed in the same way as the particulate backscatter uncertainties. This is the primary quality assurance metric for the extinction profiles.

    File Metadata Parameters

    Product_ID
    Units: NoUnits
    Format: Char
    Valid range: CAL_LID_L3_Stratospheric_APro
    Definition: An 80-byte maximum character string specifying the data product name. This will be “CAL_LID_L3_Stratospheric_APro”.

    Date_Time_of_Production
    Units: NoUnits
    Format: Char
    Valid range: 4/2006 - 12/2026
    Definition: A 27-byte character string that defines the date at granule production. The format is yyyy-mm-ddThh:mm:ssZ.

    Nominal_Year_Month
    Units: NoUnits
    Format: Char
    Valid range: 200606 - present
    Definition: A six-digit integer indicating the year and month when data within the level 3 file was measured by CALIPSO in the format yyyymm.

    Number_of_Level_1_Files_Analyzed
    Units: NoUnits
    Format: UInt_16
    Valid range: 1...451
    Definition: This integer field specifies the number of Level 1B files that are included for analysis from this month.

    List_of_Level_1_Input_Files
    Units: NoUnits
    Format: UInt_16
    Valid range: 1...451
    Definition: This field lists all the nighttime Level 1 files that are used in the analysis for the current month.

    List_of_Level_2_5kmMerged_Input_Files
    Units: NoUnits
    Format: UInt_16
    Valid range: 1...451
    Definition: This field lists all the corresponding Level 2 5 km merged layer files used in the analysis for the current month.

    List_of_Level_2_PSC_Input_Files
    Units: NoUnits
    Format: UInt_16
    Valid range: 1...31
    Definition: This field lists all the Level 2 PSC files that are used in the analysis for the current month.

    Initial_Aerosol_Lidar_Ratio_532
    Units: sr
    Format: Float_32
    Definition: The value of the initial lidar ratio used for extinction retrievals. A constant value of 50 sr is used for all calculations.

    Initial_Aerosol_Lidar_Ratio_Uncertainty_532
    Units: sr
    Format: Float_32
    Definition: The value of the uncertainty on the initial lidar ratio used for extinction retrievals. A constant value of 10 sr is used for all calculations.

    Molecular_Backscatter_Cross_Section
    Units: m2·sr-1
    Format: Float_32
    Definition: The value of the molecular backscatter cross section used in computing the molecular backscatter values.

    Molecular_Extinction_Cross_Section
    Units: m2
    Format: Float_32
    Definition: The value of the molecular extinction cross section used to compute the molecular extinction coefficients which in turn are used for the two way transmission calculations.

    Ozone_Absorption_Cross_Section
    Units: m2
    Format: Float_32
    Definition: The value of the ozone absorption cross section used to compute the ozone absorption coefficient which is used in the two way transmission calculations.




    NASA
    Last Updated: August 10, 2018
    Curator: Charles R. Trepte
    NASA Official: Charles R. Trepte

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