CALIPSO quality statements Lidar Level 2 Cloud and aerosol Layer products

Introduction

Cloud and aerosol Layer products document the spatial location of major geophysical variables, the surrounding meteorological conditions (such as temperature and pressure), and some of the optical properties of measurements and derivations. The optical properties of the direct measurement include the integral decay backward scattering, the volumetric offset ratio, and the attenuation of the total color ratio. The derived optical properties are properties that can only be obtained by applying CALIPSO extinction inversion.
Optical thickness is the main derivative optical property recorded in the layer product. Other include ice water path, particle depolarization ratio and particle color ratio. CALIPSO Cloud and aerosol layer products

Overview
CALIPSO Cloud and aerosol layer products are built around two tightly coupled data types. Layer products are generated in three different spatial resolutions.
1/3 km layer products record the cloud detection information obtained at the highest spatial resolution of lidar: horizontal 1/3 km, vertical 30 m. Due to the limited downlink bandwidth of the CALIPSO, this full-resolution data can only be down to 0.5 km below sea level at 8.3 km above the average sea level.
1 km The horizontal resolution of the product record is 1 km, and the cloud detection information is obtained from the vertical range of 20.2 km above sea level up to 0.5 km below the surface.
5 km layer products record cloud and aerosol probing information on a horizontal grid of 5 km. There are currently no separate stratospheric data products.

Definition of data maturity

Maturity Level	Description
Beta	Earlier versions of the product allowed users to familiarize themselves with data formats and parameters. Users are strongly advised not to blindly use these data products as a basis for research findings, journal publications and/or presentations.
Provisional	A limited comparison with independent sources has been completed, and the apparent manual repair is fixed.
valldated Stage 1	Estimate uncertainties by independent measurements at selected locations and times.
valldated Stage 2	Uncertainty is estimated through more widely distributed independent measurements.
valldated Stage 3	Uncertainty is estimated by independent measurements representing global conditions.
External	Data is not CALIPSO measurement results, but is obtained from external sources (such as the global Modeling and Assimilation Authority (GMAO)) or a fixed constant in the CALIPSO retrieval algorithm.

Column Time Parameters

Day Night Flag
Profile Time
Profile Time UTC Column geolocation Information

Latitude
Longitude Column spacecraft Orientation

Off Nadir Angle
scattering Angle
Solar Azimuth Angle
Solar Zenith Angle
spacecraft Position Column Surface Properties

DEM Surface elevation (external)
The surface height of LIDAR coverage obtained from the GTOPO30 digital elevation is higher than the local average sea level (DEM). 5 km layer products record the minimum, maximum, average, and standard deviation of all DEM surface samples along the 5-point limit.
IGBP Surface Type (external)
Lidar Surface elevation (ValStage1)
NSIDC Surface Type (external)
Surface elevation Detection Frequency (ValStage1; 5 miles Products only Column meteorological Data

Surface wind speed (external, aerosol products only)
tropopause Height (external)
tropopause Temperature (external) Column Optical Properties

Column Feature fraction (ValStage1; 5-km products only)
A portion of the 5km horizontal average cross section between 30 km and DEM surface elevation is determined to contain a feature (i.e. cloud, aerosol or stratosphere).
Column Integrated Attenuated backscatter 532 (ValStage1; 5-km products only)
For the 532nm total attenuation of the post-scattering coefficients of the cylindrical integral. The limit of points is from the beginning
The backscattering signal at 〜40 km until the distance unit before the elevation specified by the digital elevation
。 This quantity represents the total attenuation backscattering of a column of measurements.
Column IAB cumulative probability (ValStage1; 5-km products only)
The cumulative probability distribution of the total integral attenuation backscattering value is measured. The value of this field is between 0 and 1.
Column Optical Depth Cloud 532 (provisional; 5-km products only)
The optical thickness of all clouds detected within the 5 km average profile.
Column Optical Depth Cloud Uncertainty 532 (provisional; 5-km products only)
The uncertainty of the column Optical Depth Cloud 532 parameter computed based on the CALIPSO version 3 extinction factor.
Column Optical Depth Aerosols 532 (provisional; 5-km products only)
The 532 nm aerosol extinction curve integral, reported in the Calisps 5 km aerosol profile product, averaged 5 km of the optical depth of all aerosols detected within the range.
Column Optical Depth Aerosols Uncertainty 532 (provisional; 5-km products only)
Column Optical Depth Aerosols 1064 (provisional; 5-km products only)
Column Optical Depth Aerosols Uncertainty 1064 (provisional; 5-km products only)
Column Optical Depth stratospheric 532 (provisional; 5-km products only)
Stratospheric columnar optical thickness.
Column Optical Depth Stratospheric uncertainty 532 (provisional; 5-km products only)
Column Optical Depth stratospheric 1064 (provisional; 5-km products only)
Column Optical Depth Stratospheric uncertainty 1064 (provisional; 5-km products only) Column QA Information

The

Calibration Altitude 532 (external)
is used to calibrate the atmospheric zone channel parallel to 532 nm, at the top and bottom elevations above the average sea level of kilometers.
Feature Finder QC (ValStage1)
requires an average of 15 consecutive laser pulses to produce the nominal 5km horizontal resolution data. We record a set of feature finder QC marks per 5 km average. Conceptually, these flags are a set of 15 Boolean values that tell the user whether a feature (cloud, aerosol, or ground echo) is detected in each of the 15 laser pulses. These flags are implemented as a 16-bit integer.
Normalization Constant Uncertainty (provisional)
Standardizes constant Uncertainty (temporary), The uncertainties in the 532nm and 1064nm calibration constants are attributable only to random errors in the backscatter measurements in the calibration area; Recorded as a relative error in the Nx2 array (i.e. DC/C d/C-dc/c), where the first column stores the uncertainty of 532nm, and the second column stores the uncertainty of 1064nm. Layer Spatial Properties

horizontal averaging (external; 5 km from products)
The horizontal average required for the feature to be detected. For all data versions prior to version 3.01, the value in this field will be 0,5,20 or 80, and 0 is the padding value; The remaining values represent the characteristics detected at an average interval of 5 km, 20 km, and 80 km respectively. The top height and layer datum height of the
layer top Altitude and layer base Altitude (ValStage1)
Layers, above the average sea level, record the top and bottom height of the layer in kilometer units. Due to the data averaging scheme, the accuracy of the CALIPSO can be measured in itself as a function of height. Between 0.5 km and ~ 8.2 km, the LIDAR has a vertical resolution of 30 meters. From 8.2 km to 20.2 km, the LIDAR has a vertical resolution of 60 meters. Above 〜20.2km, the vertical resolution is 180 meters.
number Layers Found (ValStage1)
The amount of layers found in this column; cloud data products only record the number of clouds found and aerosol data
products only record the number of aerosol layers found.
single Shot Cloud cleared fraction (ValStage1; 5 miles products only)
at the planetary boundary layer (pbl,planetary Boundar The layers detected in the Y layer are subject to an additional cloud scavenger to separate the small-scale boundary Stratus from any surrounding PBL aerosols at the highest possible spatial resolution. The Tanji purge score reports the portion of the nominal layer area removed by the cloud cleanup process (that is, the horizontal average distance multiplied by the layer height). Layer Meteorological Properties

Layer Top pressure (external)
The pressure at the top height of the layer, in units of HPA H P a hpa.
midlayer pressure (external)
The pressure at the midpoint of the layer in the vertical direction, measured in hpa h P a hpa.
Layer Base pressure (external)
Layer bottom pressure, unit hpa H P a hpa.
Layer Top Temperature (external)
Midlayer Temperature (external)
Layer Base Temperature (external)
Relative Humidity (external; 5 miles aerosol products only) Layer measured Optical Properties

Integrated Attenuated backscatter 532 (Provisional @ 5 km; ValStage1 @ 1 Miles & 1/3 miles)
532nm Integral attenuated backscatter (γ′532γ532′\gamma_{532}^{'} or IAB).