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CALIPSO HOMEUser’s Guide HOMEData Summaries →IIR Level 2 Track Product Descriptions - Versions 4.20 and 4.21

CALIPSO: Data User’s Guide - Data Product Descriptions - IIR Level 2 Track V4.20 and V4.21 Products

Create Date: March 25, 2020
Last Updated: April 29, 2020
Last Updated: October 11, 2020

10-01-2020: Version 4.21
A minor version bump (+0.01) has been applied to all CALIPSO data products due to a required upgrade to the operating system on the CALIPSO production cluster. All algorithms were re-compiled to process in this new environment with no change to the underlying science algorithms or inputs.


Introduction

This document provides a description and preliminary quality assessment of the Level 2 IIR/Lidar Track product DP2.2A, as described in Section 2.17 of the CALIPSO Data Product Catalog PC-SCI-203 Release 4.92.

The primary geophysical variables reported in the IIR Level 2 track products are the measured brightness temperatures under the lidar track in the three IIR channels (8.65, 10.60 and 12.05 μm), a scene classification, effective emissivity in each IIR channel, cloud effective diameter (De) and ice or liquid water path.

The IIR Level 2 track algorithm, described in details in Garnier et al. (2012, 2013), takes full advantage of the co-located characterization of the atmosphere provided by CALIOP. It is applied to suitable types of scenes classified using the CALIOP 5-km Cloud and Aerosol layer products. The retrievals are applied to the so-called upper level which includes either one single semi-transparent or opaque layer, or several semi-transparent layers. Emissivity retrievals require a correction for the contribution from the “background”. When the lowermost of at least two layers in the column is opaque to CALIOP, the background reference is from this opaque layer, which is called lower level. Otherwise, the reference is from the Earth surface. Upper and lower level properties inferred from CALIOP are also provided.

In the continuity of the approach developed for Version 3 (V3), IIR cloud De retrievals use the concept of microphysical index (ßeff) applied to the IIR pairs of channels (12.05, 10.6) and (12.05, 8.65), with ßeff12/10 and ßeff12/08 defined as the 12.05-to-10.6 and 12.05-to-08.65 ratios of the effective absorption optical depths, respectively. The microphysical indices are interpreted in terms of De by using Look-Up Tables (LUTs) built for several models. For ice clouds, the Version 4 (V4) algorithm uses two ice crystal models, namely severely rough “single hexagonal column” and “8-element column aggregate” elaborated from new ice properties (Yang et al., 2013; Bi and Yang, 2017), and De is retrieved using the ice crystal model that provides the best agreement with the observations in terms of relationship between ßeff12/10 and ßeff12/08. For liquid water clouds, the algorithm uses dedicated LUTs derived from Mie calculations that were added in V4.

For ice clouds, four sets of De derived from a second approach are also reported in V4. Here, the LUTs are analytical functions relating ßeff12/10 and De as derived from in situ measurements at tropical and mid-latitudes performed during the TC4 and SPARTICUS field experiments (Mitchell et al., 2018).

Input Data Summary:

  • CALIPSO IIR Level 1B product DP1.2, version V2.00.
  • CALIPSO Lidar Level 2, 5 km Cloud and Aerosol layer product DP2.1A, version V4.20.
  • CALIPSO WFC IIR Level 1B product DP1.3, 1-km registered science record, version V3.xx.
  • MERRA 2 atmospheric profiles (same as CALIOP) and surface temperature.
  • IGBP (International Geosphere/Biosphere Program) surface type and AFWA (Air Force Weather Agency) snow/ice index (same as in CALIOP products).

Output Summary:

IIR/Lidar track product, version V4.20, named after the CALIPSO Lidar Level 2 product.



Data Descriptions

In the text below we provide brief descriptions of individual data fields reported in the CALIPSO IIR/Lidar Level 2 Track products. Where appropriate, we also provide an assessment of the quality and accuracy of the data in the current release. The data descriptions are 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)
Latitude
Longitude
LIDAR_Shot_Time
LIDAR_Profile_ID
IIR_Image_Time_12_05
Brightness_Temperature_08_65, Brightness_Temperature_12_05, Brightness_Temperature_10_60
Type_of_Scene
Was_Cleared_Flag_1km
Multi_Layer_Flag
Effective_Emissivity_08_65, Effective_Emissivity_12_05, Effective_Emissivity_10_60
Effective_Emissivity_Uncertainty_08_65, Effective_Emissivity_Uncertainty_12_05, Effective_Emissivity_Uncertainty_10_60
Effective_Emissivity_Uncertainty_Terms_08_65, Effective_Emissivity_Uncertainty_Terms_12_05, Effective_Emissivity_Uncertainty_Terms_10_60
Particle_Shape_Index
Particle_Shape_Index_Confidence
Effective_Particle_Size
Effective_Particle_Size_Uncertainty
Ice_Liquid_Water_Path
Ice_Liquid_Water_Path_Confidence
Reference_Brightness_Temperature
Blackbody_Brightness_Temperature
Computed_Brightness_Temperature_Surface
Optical_Depth_12_05
Optical_Depth_12_05_Uncertainty
Optical_Depth_0532_Upper_Level
Depolarization_Upper_Level
Integrated_Backscatter_Upper_Level
Layer_Top_Height_Upper_Level
Centroid_IAB_0532_Upper_Level
Layer_Bottom_Height_Upper_Level
Layer_Top_Temperature_Upper_Level
Temperature_Centroid_IAB_0532_Upper_Level
Layer_Bottom_Temperature_Upper_Level
Layer_Top_Pressure_Upper_Level
Pressure_Centroid_IAB_0532_Upper_Level
Layer_Bottom_Pressure_Upper_Level
Ice_Water_Flag_Upper_Level
Ice_Water_Flag_QA_Upper_Level
Ice_Water_Path_CALIOP_Upper_Level
Optical_Depth_0532_Lower_Level
Depolarization_Lower_Level
Integrated_Backscatter_Lower_Level
Layer_Top_Height_Lower_Level
Centroid_IAB_0532_Lower_Level
Layer_Bottom_Height_Lower_Level
Layer_Top_Temperature_Lower_Level
Temperature_Centroid_IAB_0532_Lower_Level
Layer_Bottom_Temperature_Lower_Level
Layer_Top_Pressure_Lower_Level
Pressure_Centroid_IAB_0532_Lower_Level
Layer_Bottom_Pressure_Lower_Level
Ice_Water_Flag_Lower_Level
Ice_Water_Flag_QA_Lower_Level
Surface_Emissivity_08_65, Surface_Emissivity_12_05, Surface_Emissivity_10_60
IGBP_Surface_Type
Snow_Ice_Surface_Type
Surface_532_Integrated_Depolarization_Ratio
TGeotype
Initial_Surface_Temperature
Surface_Temperature
IIR_Data_Quality_Flag
Equalization_Flag
LIDAR_Data_Quality_Flag
Surrounding_Obs_Quality_Flag
High_Cloud_vs_Background_Flag
Computed_vs_Observed_Background_Flag
Regional_Background_Std_Dev_Flag
Microphysics
Dust_Stratospheric_Aerosol_Flag
Dust_Stratospheric_Aerosol_Flag_QA
Reflectance
Integrated_Water_Vapor_Path

Science Data Parameters

Latitude
Units: deg
Format: Float_32
Valid Range: -90.0...90.0
Fill Value: -9999.00
Definition: This parameter is a replicate of the parameter “Latitude” in the Level 1B IIR product. It gives the geodetic latitude at the center of the pixel.

Longitude
Units: deg
Format: Float_32
Valid Range: -180.0...180.0
Fill Value: -9999.00
Definition: This parameter is a replicate of the parameter “Longitude” in the Level 1B IIR product. It gives the geodetic longitude at the center of the pixel.

LIDAR_Shot_Time
Units: sec
Format: Float_64
Valid Range: 4.204E8...1.072E9
Fill Value: -9999.0000
Definition: This parameter is a replicate of the parameter “Lidar_Shot_Time” in the Level 1B IIR product.
Time expressed in International Atomic Time (Temps Atomique International, TAI). Units are in seconds, starting from January 1, 1993.

LIDAR_Profile_ID
Units: NoUnits
Format: Int_32
Valid Range: 1...3,153,600,000
Fill Value: -9999
Definition: This parameter, added in V4, is the profile ID of the CALIOP single shot profile collocated with the center of the IIR pixel.

IIR_Image_Time_12_05
Units: sec
Format: Float_64
Valid Range: 4.204E8...1.072E9
Fill Value: -9999.0000
Definition: This parameter is a replicate of the parameter “Image_Time_12.05” in the Level 1B IIR product.
Time expressed in International Atomic Time (Temps Atomique International, TAI). Units are in seconds, starting from January 1, 1993.

Brightness_Temperature_08_65, Brightness_Temperature_12_05, Brightness_Temperature_10_60
Units: K
Format: Float_32
Valid Range: 0.0...400.0
Fill Value: -9999.00
Definition: These parameters give the brightness temperature of IIR channels 8.65 μm, 12.05 μm, and 10.60 μm. They are calculated from the corresponding IIR Level 1B calibrated radiances (Calibrated_Radiances_8.65, Calibrated_Radiances_12.05 and Calibrated_Radiances_10.60). The conversion functions have been refined in V4 (see Table 2 in Garnier et al., 2018).

Type_of_Scene
Units: NoUnits
Format: Int_8
Valid Range: 0...99
Fill Value: -99
Definition: This parameter is the scene classification derived from the CALIOP Level 2 Cloud and Aerosol layer products, designed to select the scenes to be further analyzed in term of effective emissivity and in the meantime to be possibly compared with existing clouds classifications.

Only layers identified with a 5 or 20-km horizontal resolution are used in the analysis.

The scenes are first organized according to the background reference scene (4th column in the table below), which can be either the surface (low non-depolarizing semi-transparent aerosol layers may be accepted) or an opaque layer (lower level).

For each category, one to several semi-transparent (ST) layers can be considered as the upper level to compute the effective emissivity (3rd column in the table). Layers are high when their centroid altitude is above 7 km, and are low otherwise.

In V4, clear sky scenes (10) and scenes containing only aerosol layers (Types 51 to 57 and 64) are classified as such if Was_Cleared_Flag_1km = 0. If Was_Cleared_Flag_1km > 0, they are assigned new type of scenes (50 and 91 to 98, see “OTHERS”) and no IIR retrievals are attempted.

A low altitude ST cloud layer (Type 24) is re-classified into Type 59 if the maximum attenuated backscatter and the maximum volume depolarization ratio in the layer are smaller than 0.02 sr-1 and 6% respectively (threshold was 7 % in V3), as a possible indicator of the presence of aerosols.

In V4, scenes containing one single high ST cloud or one single high ST aerosol layer over a high opaque cloud are classified as new types 81 or 85 if the distance between the centroid altitudes of the ST and opaque layers is smaller than 1 km, and they are processed as a single layer. In V3, these scenes were assigned types 41 and 65, respectively.

The scenes which do not match the classification are reported as type 99.

Value Description Number of Layers in Upper Level Reference Type of scene V4 vs V3
CLEAR SKY, Was_Cleared_Flag_1km=0      
10 Clear sky (no aerosol layer) n/a n/a Different
AEROSOLS ONLY, Was_Cleared_Flag_1km=0      
51 1 to 4 high ST aerosol layer(s) 1 to 4 10 Different
52 1 to 4 low ST aerosol layer(s), all layers have mean volume depolarization ratio < 6% 1 to 4 10 Different
53 1 to 4 low ST aerosol layer(s), at least one layer has mean volume depolarization ratio > 6% 1 to 4 10 Different
54 1 to 4 high ST aerosol layer(s) and 1 to 3 low ST aerosol layer(s) 2 to 5 10 Different
55 1 high opaque layer 1 10 Different
56 1 low opaque aerosol layer 1 10 Different
64 1 to 4 high ST aerosol layer(s)/ 1 low opaque aerosol layer 1 to 4 56 Different
57 Any other aerosol layer(s) only 3 to 8 10 Different
CLOUDS      
20 Low opaque cloud, no aerosol, maximum volume depolarization ratio >40% 1 10 (or 52 backup) Same
70 Low opaque cloud, no aerosol, maximum volume depolarization ratio < 40% 1 10 (or 52 backup) Same
40 High opaque cloud, no aerosol, maximum volume depolarization ratio >40% 1 10 (or 52 backup) Same
80 High opaque cloud, no aerosol, maximum volume depolarization ratio < 40% 1 10 (or 52 backup) Same
81 1 high ST cloud and 1 high opaque cloud
Centroid altitudes difference < 1 km
1 10 (or 52 backup) New, 41 in V3
85 1 high ST aerosol and 1 high opaque cloud
Centroid altitudes difference < 1 km
1 10 (or 52 backup) New, 65 in V3
21 1 high ST cloud only (no aerosol) 1 10 Same
22 2 high ST clouds, no high ST aerosol layer, up to 4 low ST aerosol layers 2 10 (or 52 backup) Same
23 1 high ST cloud and 1 low ST cloud, no high ST aerosol layer, up to 4 low ST aerosol layers 2 10 (or 52 backup) Same
24 1 low ST cloud, no high ST aerosol layer, maximum 532-nm attenuated_backscatter > 0.02 sr-1 or maximum volume depolarization ratio > 6% 1 10 (or 52 backup) Different
59 1 low ST cloud, no high ST aerosol layer, maximum 532-nm attenuated_backscatter < 0.02 sr-1 and maximum volume depolarization ratio < 6%. 1 10 (or 52 backup) Different
25 2 low ST clouds only (no aerosol layer) 2 10 (or 52 backup) Same
26 3 high ST clouds 3 10 (or 52 backup) Same
27 2 high ST clouds and 1 low ST cloud 3 10 (or 52 backup) Same
67 3-4 high ST clouds and 1 low ST cloud 4 or 5 10 (or 52 backup) Same
28 1 high ST cloud and 2 low ST clouds 3 10 (or 52 backup) Same
68 2-3 high ST clouds and 2 low ST clouds or 3 high ST clouds and 3 low ST clouds 4 to 6 10 (or 52 backup) Same
29 3 to 7 low ST clouds only (no aerosols) 3 to 7 10 Same
31 1 high ST cloud / 1 low opaque cloud, no high ST aerosol layer, up to 4 low ST aerosol layers 1 20 Same
32 2 to 6 high ST cloud/ 1 opaque cloud 2 to 6 20 Same
62 3 to 6 ST cloud (at least 1 high ST and 1 low ST)/ 1 opaque cloud 3 to 6 20 Same
33 1 high ST cloud and 1 low ST cloud / 1 opaque cloud 2 20 Same
34 1 low ST cloud/ 1 opaque cloud 1 20 Same
39 2 to 4 low ST clouds/ 1 low opaque cloud 2 to 4 20 Same
41 1 high ST cloud/ 1 high opaque cloud
Centroid altitudes difference > 1 km
1 40 Different
42 2 high ST cloud/ 1 high opaque cloud 2 40 Same
MIXED AEROSOLS/CLOUDS      
30 1 high ST cloud / 1 to 4 low ST aerosol layers 1 52 Same
66 1 high ST aerosol layer above 1 high ST cloud and 1 low ST cloud 3 10 (or 52 backup) Same
63 1 to 4 low aerosol layers above 1 low ST cloud 2 to 5 10 (or 52 backup) Same
35 1 to 4 high ST aerosol layers / 1 low opaque cloud 1 to 4 20 Same
36 1 to 4 low ST aerosol layers / 1 low opaque cloud 1 to 4 20 Same
37 1 high ST cloud / 1 low opaque aerosol layer 1 56 Same
38 1 low ST cloud / 1 low opaque aerosol layer 1 56 Same
65 1 to 4 high ST aerosol layers / 1 high opaque cloud
If 1 high ST aerosol layer, centroid altitudes difference must be > 1 km
1 to 4 40 Different
OTHERS      
50 Clear sky (no aerosol layer) Was_Cleared_Flag_1km > 0 n/a n/a New, 10 in V3
91 1 to 4 high ST aerosol layer(s)
Was_Cleared_Flag_1km > 0
n/a n/a New, 51 in V3
92 1 to 4 low ST aerosol layer(s), all layers have mean volume depolarization ratio < 6%
Was_Cleared_Flag_1km > 0
n/a n/a New, 52 in V3
93 1 to 4 low ST aerosol layer(s), at least one layer has mean volume depolarization ratio > 6%
Was_Cleared_Flag_1km > 0
n/a n/a New, 53 in V3
94 1 to 4 high ST aerosol layer(s) and 1 to 3 low ST aerosol layer(s)
Was_Cleared_Flag_1km > 0
n/a n/a New, 54 in V3
95 1 high opaque aerosol layer
Was_Cleared_Flag_1km > 0
n/a n/a New, 55 in V3
96 1 low opaque aerosol layer
Was_Cleared_Flag_1km > 0
n/a n/a New, 56 in V3
97 Any other aerosol layers only
Was_Cleared_Flag_1km > 0
n/a n/a New, 57 in V3
98 1 to 4 high ST aerosol layer(s)/ 1 low opaque aerosol layer
Was_Cleared_Flag_1km > 0
n/a n/a New, 64 in V3
99 No classification n/a n/a Different

Was_Cleared_Flag_1km
Units: NoUnits
Format: Int_8
Valid Range: 0...15
Fill Value: -99
Definition: This parameter, added in V4, is the number of CALIOP single shot clouds in the atmospheric column seen by the 1-km IIR pixel that were cleared from the CALIOP 5-km layer products. This parameter is derived from the parameter “ssWas_Cleared” reported in the CALIOP layer products.

Multi_Layer_Flag
Units: NoUnits
Format: Float_32
Valid Range: -8,030.0...8,030.0
Fill Value: -9999.00
Definition: This flag (name changed in V4) provides the number of layers included in the upper level (ten thousands and thousands digits), as well as the difference in km between the base altitude of the uppermost layer and the top altitude of the lowermost layer (tens-units-decimals digits). Multi_Layer_Flag takes the sign of this difference, which can be negative in case of overlapping layers. When the upper level contains only one layer, this difference is set to zero and Multi_Layer_Flag = 1000.
Digits Interpretation
Tens-Units-Decimals Difference between the bottom altitude of the uppermost layer and the top altitude of the lowermost layer of the upper level.
Multi_Layer_Cloud_Flag takes the sign of this quantity. This quantity is set to zero for mono-layer cases.
Hundreds 0
Tens-thousands-and thousands Number of layers in the upper level.

Effective_Emissivity_08_65, Effective_Emissivity_12_05, Effective_Emissivity_10_60
Units: NoUnits
Format: Float_32
Valid Range: 0.0...1.0
Fill Value: -9999.00
Definition: These parameters give the effective emissivity at 8.65 μm, 12.05 μm and 10.60 μm of the upper level associated to Type_of_Scene. Unlike in V3, effective emissivities found outside the physical range [0., 1.] are reported in V4. These non-physical values are due to retrieval errors. These parameters are set to invalid if no emissivity retrievals are attempted.

Effective_Emissivity_Uncertainty_08_65, Effective_Emissivity_Uncertainty_12_05, Effective_Emissivity_Uncertainty_10_60
Units: NoUnits
Format: Float_32
Valid Range: TBD...TBD
Fill Value: -9999.00
Definition: These parameters give the estimated uncertainty in the effective emissivity at 08.65 μm, 12.05 μm and 10.60 μm.

Effective_Emissivity_Uncertainty_Terms_08_65, Effective_Emissivity_Uncertainty_Terms_12_05, Effective_Emissivity_Uncertainty_Terms_10_60
Units: NoUnits
Format: Float_32
Valid Range: TBD...TBD
Fill Value: -9999.00
Definition: These parameters, added in V4, include the three terms used to compute the estimated uncertainty in the effective emissivity. The three records report the sensitivity of the effective emissivity to (in this order):
  • - an error dTm in the measured brightness temperature,
  • - an error dTBG in the background reference brightness temperature,
  • - an error dTBB in the blackbody temperature.
  • The following temperature errors are used in V4 for the computations:

      Water Surface Non-water Surface
    dTm (K) 0.3 0.3
    dTBG (K) 1 3
    dTBB (K) 2 2

    In V3, the reported uncertainties were computed using dTm = dTBG = dTBB = 1 K.


    Particle_Shape_Index
    Units: NoUnits
    Format: Int_8
    Valid Range: 1...9
    Fill Value: -99
    Definition: This index identifies the model that was used to retrieve Effective_Particle_Size. The definition of this index is different than in V3: there was no water model in V3 and V3 ice crystals models were from the database described in Yang et al. (2005).
    Value Interpretation
      V4 V3
    1 Water N/A
    7 Severely rough 8-element column aggregate Aggregate
    8 N/A Plate
    9 Severely rough single hexagonal column Solid Column

    If all the layers are liquid water clouds, the water model is used. If all the layers are ice clouds, the ice model is determined by minimizing the mean squared difference between the retrieved (ßeff12/10, ßeff12/08) pair of microphysical indices and the ensemble of pairs available in the ice LUTs. If at least one cloud layer has an unknown phase, or in case of multi-layer systems that include both ice and water clouds, both the ice and water models are considered in the search of the best agreement with the retrievals. If only one microphysical index could be computed (because effective emissivity at 08.65 or at 10.60 μm is negative or larger than 1), the model is guessed. Retrievals are not attempted for aerosol layers, except for stratospheric aerosol layers classified as “PSC aerosol” or “volcanic ash” that may be ice clouds, in case of misclassification. In these specific cases, ice models are used.

    This parameter is set to invalid if none of the ßeff12/10 and ßeff12/08 microphysical indices can be computed or if no microphysical retrievals are attempted.


    Particle_Shape_Index_Confidence
    Units: NoUnits
    Format: Int_8
    Valid Range: 1...4
    Fill Value: -99
    Definition: This index reflects the agreement between the retrieved (ßeff12/10, ßeff12/08) pair of microphysical indices and the selected model. When both ßeff12/10 and ßeff12/08 are within the expected range of values according to the look-up tables, this index reflects the relative difference between the associated effective diameters De12/10 and De12/08. Confidence is considered as good (1) when both diameters agree within 30% and medium (2) otherwise. When only one microphysical index can be computed, the V4 algorithm uses a best guess model and this index is set to 3. When at least one microphysical index is not within the expected range of values, this index is set to 4 (no confidence). A fill value indicates that none of the microphysical indices can be computed or that no microphysical retrievals are attempted.

    Value Interpretation
    1 Good confidence
    2 Medium confidence
    3 Best guess model used
    4 No confidence

    Effective_Particle_Size
    Units: microns
    Format: Float_32
    Valid Range: 0.0...200.0
    Fill Value: -9999.00
    Definition: This parameter if the effective diameter De of the upper level associated to Type_of_scene. When both ßeff12/10 and ßeff12/08 microphysical indices can be retrieved, this parameter is the mean of the effective diameters De12/10 and De12/08 retrieved from the respective microphysical indices and the model identified in Particle_Shape_Index. When only one microphysical index can be computed, De is retrieved from this microphysical index using the best guess model. Effective_Particle_Size should not be used when the microphysical indices are not within the expected range of values, that is when Particle_Shape_Index_Confidence is equal to 4.

    The full set of De12/10 and De12/08 associated to each shape is provided in Microphysics, which includes also De12/10 derived from ßeff12/10 and four LUTs established during field campaigns (Mitchell et al., 2018).


    Effective_Particle_Size_Uncertainty
    Units: microns
    Format: Float_32
    Valid Range: 0.0...200.0
    Fill Value: -9999.00
    Definition: Definition: This parameter is the estimated absolute uncertainty in the effective diameter reported in Effective_Particle_Size. In V4, it is inferred from the estimated uncertainty in the microphysical indices. When the microphysical indices are outside the range of values available in the LUTs, the uncertainty is not estimated.

    Ice_Liquid_Water_Path
    Units: g·m-2
    Format: Float_32
    Valid Range: 0.0...1300.0
    Fill Value: -9999.00
    Definition: This parameter is an estimate of the ice water path when the upper level includes only ice clouds and of the liquid water path when the upper level includes only water clouds.

    Ice_Liquid_Water_Path_Confidence
    Units: g·m-2
    Format: Float_32
    Valid Range: 0.0...1300.0
    Fill Value: -9999.00
    Definition: This parameter is the estimated absolute uncertainty in the ice or liquid water path reported in Ice_Liquid_Water_Path.

    Reference_Brightness_Temperature
    Units: K
    Format: Int_16
    Valid Range: 0.0...400.0
    Fill Value: -9999
    Scale Factor: 100.00
    Offset: 100.00
    Scale Equation: data/scale_factor + offset
    Comments: ordered as 08.65, 10.60, 12.05 μm, 08.65, 10.60, 12.05 μm
    Definition: This parameter includes six records. The first three records are the background reference brightness temperatures at 08.65 μm, 10.60 μm, and 12.05 μm, as computed using the FASRAD radiative transfer model (Dubuisson et al., 2005) and using Temperature_Centroid_IAB_0532_Lower_Level if the reference is an opaque layer. The last three records are the background reference brightness temperatures used to retrieve the effective emissivity of the upper level. They may differ from the first three records when the reference is measured in neighboring pixels (cf High_Cloud_vs_Background) or if the opaque reference is an ice layer. This parameter is a fill value if no effective emissivity retrievals are attempted.

    Blackbody_Brightness_Temperature
    Units: K
    Format: Int_16
    Valid Range: 0.0...400.0
    Fill Value: -9999
    Scale Factor: 100.000
    Offset: 100.000
    Scale Equation: data/scale_factor + offset
    Comments: ordered as 08.65, 10.60, 12.05 μm, 08.65, 10.60, 12.05 μm
    Definition: This parameter includes six records. The first three records are the blackbody brightness temperatures at 08.65 μm, 10.60 μm, and 12.05 μm, as computed using the FASRAD radiative transfer model (Dubuisson et al., 2005) and Temperature_Centroid_IAB_0532_Upper_Level. The last three records are the blackbody brightness temperatures used to retrieve the effective emissivity of the upper level. Due to corrections introduced in the algorithm, they may differ from the first three records when the upper level is composed of ice clouds. This parameter is a fill value if no effective emissivity retrievals are attempted.

    Computed_Brightness_Temperature_Surface
    Units: K
    Format: Int_16
    Valid Range: 0.0...400.0
    Fill Value: -9999
    Scale Factor: 100.000
    Offset: 100.000
    Scale Equation: data/scale_factor + offset
    Comments: ordered as 08.65, 10.60 and 12.05 μm
    Definition: This parameter is the equivalent brightness temperature of the clear sky surface radiance as computed using the FASRAD radiative transfer model (Dubuisson et al., 2005). FASRAD uses atmospheric profiles and skin temperatures from the MERRA 2 model, and surface emissivities reported in the product. (see Surface_Emissivities). This parameter is reported for all types of scenes in V4.

    Optical_Depth_12_05
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...10.0
    Fill Value: -9999.00
    Definition: This parameter is the effective absorption optical depth at 12.05 μm derived from the effective emissivity at 12.05 μm if the latter is found between 0 and 1. Absorption optical depths larger than 10 (i.e. effective emissivity at 12.05 μm larger than 0.9999546) are not reported.

    Optical_Depth_12_05_Uncertainty
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...10.0
    Fill Value: -9999.00
    Definition: This parameter is the estimated absolute uncertainty in Optical_Depth_12_05. Uncertainties larger than 10 are not reported.

    Optical_Depth_0532_Upper_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...20.0
    Fill Value: -9999.00
    Definition: This parameter is the summation of the layers’ optical depths at 532 nm as provided in the CALIOP lidar Level 2 Cloud and/or Aerosol layer products for the layers included in the upper level. This parameter is set to invalid when no IIR retrievals are attempted.

    Depolarization_Upper_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter is the upper level’s integrated particulate depolarization ratio derived from CALIOP observations, where the contribution of each layer of the upper level depends on its integrated particulate depolarization ratio, its 532-nm integrated attenuated backscatter and the 532-nm overlying two-way transmittance. The computation was different in V3. This parameter is set to invalid when no IIR retrievals are attempted.

    Integrated_Backscatter_Upper_Level
    Units: sr-1
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter is the upper level’s 532-nm integrated attenuated backscatter (IAB) derived from CALIOP observations. It is the summation of the layers’ individual 532-nm integrated attenuated backscatter as reported in the CALIOP Level 2 Cloud and/or Aerosol layer products weighted by their overlying 532-nm two-way transmittance. The computation was different in V3. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Top_Height_Upper_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Layer_Top_Altitude” reported in the CALIOP Level 2 Cloud or Aerosol layer product for the uppermost layer in the upper level. Because the algorithm only accounts for features detected with 5 or 20 km horizontal averaging, the uppermost layer reported here can be lower than in the CALIOP product. This parameter is set to invalid when no IIR retrievals are attempted.

    Centroid_IAB_0532_Upper_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is the upper level centroid altitude seen by IIR. This parameter is the weighted average of the centroid altitudes of the layers included in the upper level, by using as a weight the product of the 532-nm integrated attenuated backscatter and of the overlying 532-nm two-way transmittance of each layer. The computation was different in V3. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Bottom_Height_Upper_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Layer_Base_Altitude” reported in the CALIOP Level 2 Cloud or Aerosol layer product for the lowermost layer in the upper level. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Top_Temperature_Upper_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter is the temperature at Layer_Top_Height_Upper_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product. This parameter is set to invalid when no IIR retrievals are attempted.

    Temperature_Centroid_IAB_0532_Upper_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter is the upper level centroid temperature derived from Centroid_IAB_0532_Upper_Level and MERRA 2 profiles. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Bottom_Temperature_Upper_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the temperature at Layer_Bottom_Height_Upper_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Top_Pressure_Upper_Level
    Units: hPa
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the pressure at Layer_Top_Height_Upper_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product. This parameter is set to invalid when no IIR retrievals are attempted.

    Pressure_Centroid_IAB_0532_Upper_Level
    Units: hPa
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the upper level’s centroid pressure derived from Centroid_IAB_0532_Upper_Level and MERRA 2 profiles. This parameter is set to invalid when no IIR retrievals are attempted.

    Layer_Bottom_Pressure_Upper_Level
    Units: hPa
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the pressure at Layer_Bottom_Height_Upper_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product. This parameter is set to invalid when no IIR retrievals are attempted.

    Ice_Water_Flag_Upper_Level
    Units: NoUnits
    Format: Int_8
    Valid Range: 1...9
    Fill Value: -99
    Definition: This parameter, added in V4, is built from “Ice/Water Phase” reported in the parameter “Feature_Classification_Flags” of the CALIOP Level 2 Cloud layer product, as shown in the following table:
    Ice_Water_Flag_Upper_Level Description Interpretation
    1 CALIOP Ice/Water phase=1, all layers randomly oriented ice crystals (ROI)
    2 CALIOP Ice/Water phase=2, all layers liquid water
    3 CALIOP Ice/Water phase=3, all layers horizontally oriented ice crystals (HOI)
    4 CALIOP Ice/Water phase=1 and 3 ice crystals only, both ROI and HOI
    6 CALIOP Ice/Water phase=(1 or 3) and 2 (ROI and/or HOI) ice and liquid water
    9 at least one layer has CALIOP Ice/Water phase=0 at least one layer has unknown/not determined phase.
    -99 fill value no cloud layer in upper level or retrievals not attempted.

    Ice_Water_Flag_QA_Upper_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...100.1
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is built from “Feature Type QA” and “Ice/Water Phase QA” reported in the parameter “Feature_Classification_Flags” of the CALIOP Level 2 Cloud layer product. For each layer of the upper level, “Feature Type QA” and “Ice/Water Phase QA” are converted into scores, chosen between 0 and 100, as shown in the table below.
    Feature_Type_score CALIOP Feature Type QA Ice/Water_Phase_score CALIOP Ice/Water Phase QA
    100 high 100 high
    50 medium 50 medium
    25 low 25 low
    0 none 0 none

    The Feature Type and Ice/Water Phase scores assigned to the upper level are the mean scores. Finally, the mean scores are combined into Ice_Water_Flag_QA_Upper_Level as

    Feature_Type_score + 0.001 x Ice/Water_Phase_score

    This parameter is a set to invalid if the upper level does not contain cloud layers or when no retrievals are attempted.

    Example: Ice_Water_Flag_QA_Upper_Level = 75.1 means: a) Feature_Type_score = 75 (medium to high confidence in the cloud/aerosol classification for the cloud layers included in the upper level) and b) Ice/Water_Phase_score = 100 (high confidence in the Ice/Water phase classification for all the cloud layers included in the upper level).


    Ice_Water_Path_CALIOP_Upper_Level
    Units: g·m-2
    Format: Float_32
    Valid Range: TBD...TBD
    Fill Value: -9999.00
    Definition: This parameter is the summation of the layers’ ice water paths reported in the CALIOP Level 2 Cloud layer product for the ice layers included in the upper level. This parameter is set to invalid when no effective emissivity retrievals are attempted.

    Optical_Depth_0532_Lower_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...5.0
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Feature_Optical_Depth_532” parameter reported in the CALIOP Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Depolarization_Lower_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Integrated_Particulate_Depolarization_Ratio” reported in the CALIOP lidar Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Integrated_Backscatter_Lower_Level
    Units: sr-1
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Integrated_Attenuated_Backscatter_532” reported in the CALIOP Level 2 Cloud or Aerosol layers product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Layer_Top_Height_Lower_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Layer_Top_Altitude” reported in the CALIOP Level 2 Cloud or Aerosol layers product for the lower level, if any, according to “Type_of_Scene”. Otherwise, this parameter is set to invalid.

    Centroid_IAB_0532_Lower_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is the centroid altitude of the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid. It is a replicate of the centroid altitude provided in the parameter “Attenuated_Backscatter_Statistics_532” of the CALIOP Level 2 Cloud or Aerosol layer product.

    Layer_Bottom_Height_Lower_Level
    Units: km
    Format: Float_32
    Valid Range: -0.5...30.1
    Fill Value: -9999.00
    Definition: This parameter is a replicate of the parameter “Layer_Base_Altitude” reported in the CALIOP Level 2 Cloud or Aerosol layers product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Layer_Top_Temperature_Lower_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter is the temperature at Layer_Top_Height_Lower_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Temperature_Centroid_IAB_0532_Lower_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter is the centroid temperature of the lower level if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid. It is derived from Centroid_IAB_0532_Lower_Level and MERRA 2 profiles.

    Layer_Bottom_Temperature_Lower_Level
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the temperature at Layer_Bottom_Height_Lower_Level replicated from the CALIOP Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Layer_Top_Pressure_Lower_Level
    Units: hPA
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is a replicate of the parameter “Layer_Top_Pressure” reported in the CALIOP Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Pressure_Centroid_IAB_0532_Lower_Level
    Units: hPA
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the centroid pressure derived from Centroid_IAB_0532_Lower_Level and MERRA 2 profiles for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Layer_Bottom_Pressure_Lower_Level
    Units: hPA
    Format: Float_32
    Valid Range: 1.0...1086.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is a replicate of the parameter “Layer_Base_Pressure” reported in the CALIOP Level 2 Cloud or Aerosol layer product for the lower level, if any, according to Type_of_Scene. Otherwise, this parameter is set to invalid.

    Ice_Water_Flag_Lower_Level
    Units: NoUnits
    Format: Int_8
    Valid Range: -9...9
    Fill Value: -99
    Definition: This parameter, added in V4, uses “Ice/Water Phase” of the lower level as reported in the parameter “Feature_Classification_Flags” of the CALIOP Level 2 Cloud layer product. This flag is assigned specific values if the lower level is an aerosol layer, or if the reference is the surface or if no retrievals are attempted (see Type_of_Scene). It is set to invalid if Type_of_Scene is not defined.
    Ice_Water_Flag_Lower_Level CALIOP Ice/Water Phase Interpretation
    1 1 randomly oriented ice crystals (ROI)
    2 2 liquid water
    3 3 horizontally oriented ice crystals (HOI)
    9 0 unknown/not determined
    5 N/A lower level is an aerosol layer
    -9 N/A background reference is surface or retrievals not attempted
    -99 (fill value) N/A Type of Scene not defined.

    Ice_Water_Flag_QA_Lower_Level
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...100.1
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is built from “Feature Type QA” and “Ice/Water Phase QA” reported in the parameter “Feature_Classification_Flags” of the CALIOP Level 2 Cloud layer product. “Feature Type QA” and “Ice/Water Phase QA” of the lower level (if any) are converted into scores, chosen between 0 and 100, as shown in the table below. If the lower level is an aerosol layer, Ice/Water Phase score is set to 0.
    Feature_Type_score CALIOP Feature Type QA Ice/Water_Phase_score CALIOP Ice/Water Phase QA
    100 high 100 high
    50 medium 50 medium
    25 low 25 low
    0 none 0 none

    The Feature Type and Ice/Water Phase scores are then combined into Ice_Water_Flag_QA_Lower_Level as Feature_Type_score + 0.001 x Ice/Water_Phase_score.


    Surface_Emissivity_08_65, Surface_Emissivity_12_05, Surface_Emissivity_10_60
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: These parameters are the surface emissivities for channels 08.65, 12.05 and 10.60 μm respectively. They have been revisited in V4 after the analysis of IIR observations in clear sky conditions. They are determined according to the TGeotype category. For snow-free land pixels, surface emissivity at 08.65 μm and at 10.60 μm are determined from monthly nighttime and daytime maps (resolution: latitude x longitude = 1° x 2°).
      Surface Emissivity
    Category 08.65 μm 10.60 μm 12.05 μm
    Water 0.971 0.984 0.982
    Water/sea ice transition 0.981 0.990 0.982
    Sea ice 0.981 0.990 0.982
    Snow 0.966 0.977 0.975
    Snow-free land Monthly maps
    (Night and Day)
    Monthly maps
    (Night and Day)
    0.975

    IGBP_Surface_Type
    Units: NoUnits
    Format: Int_8
    Valid Range: 1...18
    Fill Value: -99
    Definition: This parameter, added in V4, is a replicate of the parameter “IGBP_Surface_Type” provided in the CALIOP Level 2 layer products. Reports the IGBP (International Geosphere/Biosphere Program) surface type.

    Snow_Ice_Surface_Type
    Units: NoUnits
    Format: UInt_8
    Valid Range: 0...255
    Fill Value: 99
    Definition: This parameter, added in V4, is a replicate of the parameter “Snow_Ice_Surface_Type” reported in the CALIOP Level 2 layer products. Reports the AFWA (Air Force Weather Agency) Snow and Ice map.

    Surface_532_Integrated_Depolarization_Ratio
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is a replicate of the parameter “Surface_532_Integrated_Depolarization_Ratio” reported in the CALIOP Level 2 layer products.

    TGeotype
    Units: NoUnits
    Format: Int_16
    Valid Range: 100...1800
    Fill Value: -9999
    Definition: This parameter, added in V4, is derived from IGBP_Surface_Type and uses Surface_532_Integrated_Depolarization_Ratio, if available, and Snow_Ice_Surface_Type to identify pixels covered with sea ice or snow and to refine the classification around coastlines.
    Category TGeotype Interpretation
    Water 1700 IGBP water (17) and surface depolarization ratio < 0.15 or snow ice surface type = 0.
    1705 Surface depolarization not available and 0 < snow ice surface type < 50.
    1750 Coastline land (IGBP ≠ 17) pixel changed to water because surface depolarization ratio < 0.15.
    Water/sea ice transition 1710 IGBP water (17) 0.15 ≤ surface depolarization ratio ≤ 0.6
    Sea ice 1510 IGBP water (17) Surface depolarization > 0.6 or snow ice surface type ≥ 50
    Snow 1560 Land (IGBP ≠17) Surface depolarization > 0.6 or snow ice surface type ≥ 50
    Snow-free land IGBP x 100 Land (IGBP ≠17) Surface depolarization < 0.6 or snow ice surface type = 0.
    1730 Coastline water (IGBP =17) pixel changed to snow-free land because 0.15 ≤ surface depolarization ratio ≤ 0.6.

    Initial_Surface_Temperature
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the MERRA 2 skin temperature.

    Surface_Temperature
    Units: K
    Format: Float_32
    Valid Range: 160.0...340.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the skin temperature used for the emissivity retrievals. For pixels located over snow-free land, the initial MERRA 2 skin temperature is corrected using monthly nighttime and daytime correction maps (resolution: latitude x longitude = 1° x 2°) established from the analysis of IIR observations in clear sky conditions.

    IIR_Data_Quality_Flag
    Units: NoUnits
    Format: Int_8
    Valid Range: 0...15
    Fill Value: -99
    Definition: This parameter is an indicator of the IIR calibrated radiance quality and is extracted from the parameter “Pixel_Quality_Index” of the IIR Level 1 product.

    If not zero, corresponding to nominal quality:

    • either one channel has poor quality or is missing, or
    • the radiances in the 3 channels are not all part of the same image measurement sequences which, for scenes with high broken clouds, could lead to some errors at the edge of the images for geometrical reasons.

    Bit Bit Value Interpretation
    1 0 IIR calibrated radiances in the 3 channels are of nominal quality
    1 At least one of the channels has poor quality or is missing
    2 0 Channels 08.65 and 10.60 derived from the same sequence of acquisition
    1 Channels 08.65 and 10.60 not derived from the same sequence of acquisition
    3 0 Channels 08.65 and 12.05 derived from the same sequence of acquisition
    1 Channels 08.65 and 12.05 not derived from the same sequence of acquisition
    4 0 Channels 10.60 and 12.05 derived from the same sequence of acquisition
    1 Channels 10.60 and 12.05 not derived from the same sequence of acquisition
    5-8 0 N/A

    Equalization_Flag
    Units: NoUnits
    Format: Int_8
    Valid Range: 0...7
    Fill Value: -99
    Definition: This parameter, added in V4, is extracted from the parameter “Pixel_Quality_Index” of the IIR Version 2.00 Level 1B product. It indicates whether an equalization correction has been applied.
    Bit Bit Value Interpretation
    Equalization Correction
    1 0 Channel 12.05: no
    1 Channel 12.05: yes
    2 0 Channel 10.60: no
    1 Channel 10.60: yes
    3 0 Channel 08.65: no
    1 Channel 08.65: yes
    4-8 0 N/A

    LIDAR_Data_Quality_Flag
    Units: NoUnits
    Format: Int_8
    Valid Range: 0 : lowest / 1 : intermediate / 2 : high / 3 : highest
    Fill Value: -99
    Definition: This flag is the Feature Type QA derived from the parameter "Feature_Classification_Flag" in the CALIOP lidar Level 2 layer products for the uppermost layer in the upper level.
    Value Interpretation : Feature QA from Feature_Classification_Flag
    0 none
    1 low
    1 medium
    2 high

    Surrounding_Obs_Quality_Flag
    Units: NoUnits
    Format: Int_16
    Valid Range: 0...412
    Fill Value: -9999
    Definition: This flag is a composite of 3 different pieces of information:
    • the units digit indicates if the studied pixel is isolated or part of a structure with consecutive IIR pixels of same Type_of_scene. It is not computed for scenes containing only aerosols, for type of scene 20, or when no IIR retrievals are attempted.
    • the tens digit is a mineral aerosols index based on IIR inter-channels brightness temperature differences (BTD). Mineral aerosols layers are identified (tens digit=1) when the 08_65 minus 12_05 BTD is < -2K and the 10_60 minus 12_05 BTD is < -0.5 K.
    • the hundreds digit is an index describing the difference between observed and computed brightness temperatures for specific types of scenes: scenes identified as clear sky (10) or containing low aerosols (52, 53) and scenes containing opaque clouds (20, 40). This index is designed to identify cloud-free and opaque cloud pixels where measured and computed brightness temperatures are exhibiting large differences and which may require further analysis.

    Digit Digit Value Digit Interpretation
    Units 0 3 or more consecutive pixels with the same Type_of_Scene
    1 2 consecutive pixels with the same Type_of_Scene
    2 Not computed
    Tens
    IIR aerosols index
    0 No mineral aerosols detected
    1 Mineral aerosols detected
    Hundreds
    Obs-Computed BTs
    0 Not computed or satisfactory for computed cases:
    Mean (Observed - Computed) Brightness Temperatures between -2K and +2K
    1 Low
    Mean (Observed - Computed) Brightness Temperatures between -5K and -2K
    2 High
    Mean (Observed - Computed) Brightness Temperatures between +2K and +5K
    3 Very low
    Mean (Observed - Computed) Brightness Temperatures < -5K
    4 Very high
    Mean (Observed - Computed) Brightness Temperatures > 5K

    High_Cloud_vs_Background_Flag
    Units: NoUnits
    Format: Float_32
    Valid Range: -93.0...412.0
    Fill Value: -9999.00
    Definition: This flag is to give the main characteristics of the background radiance used to retrieve the effective emissivity of the current pixel.

    If the background radiance is derived from reference measurements in the vicinity of the pixel, the unit digit gives an indication of the mean distance from the current pixel. If it is derived from the FASRAD model, the unit digit is set to zero.

    Depending on Type_of_Scene, the reference can be clear sky (10) or possibly low ST non-depolarizing aerosols (52), a low opaque cloud (20), a high opaque cloud (40), or a low opaque aerosols layer (56). This information is provided in the hundreds digit. When the reference is a cloud or aerosol layer selected among nearby observations (i.e. not computed), the tens digit indicates the range of values of its effective emissivity. Otherwise, it is set to 0 (computed reference) or -9 (clear sky).

    Digit Digit Value Digit Interpretation
    Units 0 Background reference computed
    1 Background reference measured at a distance <= 10 km
    2 Background reference measured, 10 km < distance <= 50 km
    3 Background reference measured, 50 km < distance <= 100 km
    Tens 0 Background reference computed
    1 Measured background reference effective emissivity between -0.1 and 1.1
    2 Measured background reference effective emissivity < -0.1
    3 Measured background reference effective emissivity > 1.1
    -9 Measured background reference is clear sky
    Hundreds 0 Background reference: clear sky (10)
    1 Background reference: low opaque cloud (20)
    2 Background reference: high opaque cloud (40)
    3 Background reference: low semi-transparent non-depolarizing aerosols (52)
    4 Background reference: low opaque aerosol layer (56)

    Computed_vs_Observed_Background_Flag
    Units: NoUnits
    Format: Float_32
    Valid Range: -10.0...10.0
    Fill Value: -9999.00
    Definition: This parameter is to assess the impact of computed versus measured background reference radiances in the retrieved effective emissivities. If the background reference is derived from a series of neighboring pixels (cf High_Cloud_vs_Background_Flag), this parameter gives the mean relative difference between those measurements and the computed radiances (not used to retrieve the effective emissivities). Otherwise, the parameter is set to invalid. The three elements are for the IIR channels 08.65 μm, 10.60 μm and 12.05 μm respectively.

    Regional_Background_Std_Dev_Flag
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...1.0
    Fill Value: -9999.00
    Definition: This parameter is to assess the standard deviation associated to Computed_vs_Observed_Background_Flag
    Regional_Background_Std_Dev_Flag Interpretaion
    0 Standard deviation ≤ 0.15
    1 Standard deviation > 0.15

    Microphysics
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...2002009.0
    Fill Value: -9999.00
    Definition: This parameter gives the whole set of De12/10 and De12/08 diameters inferred from the ßeff12/10 and ßeff12/08 microphysical indices as derived with the V3 algorithm (records 1 to 3) and as derived with the V4 algorithm (records 4 to 6).

    In addition, records 7 to 10 are De12/10 derived from four relationships established using in-situ aircraft data during the SPARTICUS and TC4 campaigns (Table 1 in Mitchell et al., 2018). Because of uncertainties in the first bin N(D)1 of the size distributions, two LUTs were established for each campaign, with N(D)1 unmodified or set to zero.

    Digits Interpretation
    Units Records 1 to 3: particle shape_index V3.
    Records 4 to 6: particle shape_index V4.
    Records 7 to 10: set to 0.
    Thousands-Hundreds-Tens Effective diameter De12/08 in microns
    Records 1 to 3: V3.
    Records 4 to 6: V4; set to zero if ßeff12/08 is not valid and ßeff12/10 is valid.
    Records 7 to 10: set to 0.
    Millions-Hundred thousands-Ten thousands Effective diameter De12/10 in microns
    Records 1 to 3: V3.
    Records 4 to 6: V4, set to zero if ßeff12/10 is not valid and ßeff12/08 is valid.
    Records 7 to 10: SPARTICUS N(D)1 unmodified, TC4 N(D)1 unmodified, SPARTICUS N(D)1 = 0, TC4 N(D)1 = 0.

    Dust_Stratospheric_Aerosol_Flag
    Units: NoUnits
    Format: Int_8
    Valid Range: 0...8
    Fill Value: -99
    Definition: The 7 records are the number of aerosol layers in the atmospheric column classified by CALIOP as: record #1: tropospheric dust, record #2: tropospheric polluted dust, record #3: tropospheric dusty marine, record #4: stratospheric PSC aerosol, record #5: stratospheric volcanic ash, record #6: stratospheric sulfate/other, and record #7: stratospheric elevated smoke. This parameter was added in V4.

    Dust_Stratospheric_Aerosol_Flag_QA
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...100.1
    Fill Value: -9999.00
    Definition: The 7 records are QA scores assigned to the 7 aerosol subtypes reported in Dust_Stratospheric_Aerosol_Flag. For each aerosol subtype, the QA score is computed from “Feature Type QA” and “Aerosol/PSC Type QA” reported in the parameter “Feature_Classification_Flags” of the CALIOP Level 2 Aerosol layer product. “Feature Type QA” and “Aerosol/PSC Type QA” of each layer are converted into scores, chosen between 0 and 100, as shown in the table below.
    Feature_Type_score CALIOP Feature Type QA Aerosol/PSC_Type_score CALIOP Aerosol/PSC Type QA
    100 high 100 confident
    50 medium
    25 low
    0 none 0 not confident

    The Feature Type and Aerosol/PSC Type scores assigned to the atmospheric column are the mean scores. Finally, the mean scores are combined into Dust_Stratospheric_Aerosol_Flag_QA as Feature_Type_score + 0.001 x Aerosol/PSC_Type_score.


    Reflectance
    Units: NoUnits
    Format: Float_32
    Valid Range: 0.0...2.0
    Fill Value: -9999.00
    Definition: This parameter, added in V4, is the Wide Field of view Camera reflectance replicated from the IIR WFC Level 1B product.

    Integrated_Water_Vapor_Path
    Units: g·cm-2
    Format: Float_32
    Valid Range: 0.0...10.0
    Fill Value: -9999.00
    Definition: This parameter gives the column-integrated atmospheric water vapor derived from the MERRA 2 product.


    File Metadata Parameters

    Product_ID
    an 80-byte (max) character string specifying the data product name. For the IIR Level 2 track products, the value of this string is “CAL_IIR_L2_Track”.

    Date_Time_at_Granule_Start
    a 27-byte character string that reports the date and time at the start of the file orbit segment (i.e., granule). The format is yyyy-mm-ddThh:mm:ss.ffffffZ.

    Date_Time_at_Granule_End
    a 27-byte character string that reports the date and time at the end of the file orbit segment (i.e., granule). The format is yyyy-mm-ddThh:mm:ss.ffffffZ.

    Date_Time_at_Granule_Production
    This is a 27-byte character string that defines the date at granule production. The format is yyyy-mm-ddThh:mm:ss.ffffffZ.

    Initial_IIR_Scan_Center_Latitude
    This field reports the first subsatellite latitude of the granule.

    Initial_IIR_Scan_Center_Longitude
    This field reports the first subsatellite longitude of the granule.

    Ending_IIR_Scan_Center_Latitude
    This field reports the last subsatellite latitude of the granule.

    Ending_IIR_Scan_Center_Longitude
    This field reports the last subsatellite longitude of the granule.

    Orbit_Number_at_Granule_Start
    This field reports the orbit number at the granule start time.

    Orbit_Number_at_Granule_End
    This field reports the orbit number at the granule stop time.

    Orbit_Number_Change_Time
    This field reports the time at which the orbit number changes in the granule.

    Path_Number_at_Granule_Start
    This field reports the path number at the granule start time.

    Path_Number_at_Granule_End
    This field reports the path number at the granule stop time.

    Path_Number_Change_Time
    This field reports the time at which the path number changes in the granule.

    Number_of_IIR_Records_in_File
    This field reports the number of IIR records in the file.

    Number_of_Valid_08_65_Pixels
    This field reports the number of IIR pixels in the file with valid radiance in channel 08_65.

    Number_of_Valid_12_05_Pixels
    This field reports the number of IIR pixels in the file with valid radiance in channel 12_05.

    Number_of_Valid_10_60_Pixels
    This field reports the number of IIR pixels in the file with valid radiance in channel 10_60.

    Number_of_Invalid_08_65_Pixels
    This field reports the number of IIR pixels in the file with invalid radiance in channel 08_65.

    Number_of_Invalid_12_05_Pixels
    This field reports the number of IIR pixels in the file with invalid radiance in channel 12_05.

    Number_of_Invalid_10_60_Pixels
    This field reports the number of IIR pixels in the file with invalid radiance in channel 10_60.

    Number_of_Rejected_08_65_Pixels
    This field reports the number of IIR pixels in the file in channel 08_65 rejected by the algorithm.

    Number_of_Rejected_12_05_Pixels
    This field reports the number of IIR pixels in the file in channel 12_05 rejected by the algorithm.

    Number_of_Rejected_10_60_Pixels
    This field reports the number of IIR pixels in the file in channel 10_60 rejected by the algorithm.

    Number_of_Rejected_08_65_Pixels_Location
    This field reports the number of IIR pixels in the file in channel 08_65 rejected by the algorithm due to collocation.

    Number_of_Rejected_12_05_Pixels_Location
    This field reports the number of IIR pixels in the file in channel 12_05 rejected by the algorithm due to collocation.

    Number_of_Rejected_10_60_Pixels_Location
    This field reports the number of IIR pixels in the file in channel 10_60 rejected by the algorithm due to collocation.

    Number_of_Rejected_08_65_Pixels_Radiance
    This field reports the number of IIR pixels in the file in channel 08_65 rejected by the algorithm due to radiance.

    Number_of_Rejected_12_05_Pixels_Radiance
    This field reports the number of IIR pixels in the file in channel 12_05 rejected by the algorithm due to radiance.

    Number_of_Rejected_10_60_Pixels_Radiance
    This field reports the number of IIR pixels in the file in channel 10_60 rejected by the algorithm due to radiance.

    Mean_08_65_Radiance_All
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 08_65 for the non-rejected pixels.

    Mean_12_05_Radiance_All
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 12_05 for the non-rejected pixels.

    Mean_10_60_Radiance_All
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 10_60 for the non-rejected pixels.

    Mean_08_65_Radiance_Selected_Cases
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 08_65 for the cases selected for emissivity retrievals.

    Mean_12_05_Radiance_Selected_Cases
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 12_05 for the cases selected for emissivity retrievals.

    Mean_10_60_Radiance_Selected_Cases
    This field reports the mean radiance (in W·m-2·sr-1·μm-1) in the file in channel 10_60 for the cases selected for emissivity retrievals.

    Mean_08_65_Brightness_Temp_All
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 08_65 for the non-rejected pixels.

    Mean_12_05_Brightness_Temp_All
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 12_05 for the non-rejected pixels.

    Mean_10_60_Brightness_Temp_All
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 10_60 for the non-rejected pixels.

    Mean_08_65_Brightness_Temp_Selected_Cases
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 08_65 for the cases selected for emissivity retrievals.

    Mean_12_05_Brightness_Temp_ Selected_Cases
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 12_05 for the cases selected for emissivity retrievals.

    Mean_10_60_Brightness_Temp_ Selected_Cases
    This field reports the mean brightness temperature (in Kelvin) in the file in channel 10_60 for the cases selected for emissivity retrievals.

    Number_of_Valid_LIDAR_Pixels
    This field reports the number of records in the lidar input product available at IIR pixel resolution.

    Number_of_Invalid_LIDAR_Pixels
    This field is set to 0.

    Number_of_Rejected_LIDAR_Pixels
    This field is set to 0.

    Number_of_Selected_Cloud_Cases
    This field reports the number of pixels in the file selected for emissivity retrievals with at least one cloud layer.

    Percent_of_Selected_Cloud_Cases
    This field reports the percentage of pixels in the file selected for emissivity retrievals with at least one cloud layer.

    Number_of_Selected_Aerosol_Cases
    This field reports the number of pixels in the file selected for emissivity retrievals with only aerosol layers.

    Percent_of_Selected_Aerosol_Cases
    This field reports the percentage of pixels in the file selected for emissivity retrievals with only aerosol layers.

    Number_of_Identified_Pixels_Clear_Sky
    This field reports the number of “clear sky” pixels in the file (i. e no clouds and no aerosols).

    Percent_of_Identified_Pixels_Clear_Sky
    This field reports the number of “clear sky” pixels in the file (i. e no clouds and no aerosols).

    Mean_Altitude_High_Cloud
    This field reports the mean centroid altitude (in km) for high clouds retrievals.

    GEOS_Version
    This is a 64-byte character that reports the version of the MERRA-2 data product provided by the GMAO.


    Data Quality Statements

    IIR Level 2 Track Product Information
    Release Date Version Data Date Range Production Strategy
    October 12, 2020 4.21 July 01, 2020 - present Standard
    April 27, 2020 4.20 June 13, 2006 - June 30, 2020 Standard


    NASA
    Last Updated: November 22, 2021
    Curator: Charles R. Trepte
    NASA Official: Charles R. Trepte

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