LIDAR Aerosol Extinction Inversion Below Clouds Using Feedback Calibration

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Solution Overview

Problem

Existing LIDAR methods struggle to accurately invert the aerosol extinction coefficient below clouds due to the inability to determine a calibration point altitude when low and thick clouds are present, leading to inaccurate inversion results.

Innovation Solution

An inversion method that includes obtaining a first calibration value from a horizontal echo signal, determining a cloud base calibration point, and iteratively adjusting a second calibration value until the difference between the first and second values meets a specified relative error, using methods like slope and Fernald backward integration to achieve accurate inversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the Fernald method is used to obtain aerosol extinction coefficient through backward integration, then the vertical aerosol extinction profile can be obtained, but the method requires a calibration point altitude with low aerosol content which cannot be determined when low and thick clouds are present

Engineering Contradiction:

Improveaerosol extinction coefficient inversion accuracyVSAvoidmethod applicability under cloudy conditions

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

Instead of using the traditional forward integration method that requires a known calibration point, the patent employs backward integration from the cloud top altitude. The inversion process starts with an assumed extinction coefficient at cloud top and iteratively adjusts it by comparing horizontal and vertical profiles until consistency is achieved, thereby eliminating the need for a pre-determined calibration point in clear air

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements an iterative feedback mechanism where the horizontally homogeneous assumption provides an initial extinction coefficient that is compared with the vertically integrated profile. The difference between these profiles feeds back into adjusting the cloud top extinction coefficient until convergence is reached within a specified error threshold, ensuring self-consistency of the inversion results

Inventive Principle:

Principle #23Feedback

2Loss of information

If laser detection is performed through low and thick clouds, then echo signals can be obtained, but the laser cannot penetrate through the clouds making it impossible to determine calibration point altitude

Engineering Contradiction:

Improvecalibration point information availabilityVSAvoidcloud blocking effect on laser

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the calibration information from the cloud top region rather than requiring clear air calibration points below. By determining the cloud base altitude through signal analysis and using the cloud top as the new calibration reference, the method separates the calibration function from the traditional clear air requirement, allowing calibration to proceed despite cloud presence

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The cloud top altitude serves as an intermediary calibration surface between the LIDAR system and the aerosol layer of interest. Rather than attempting to penetrate through clouds to reach clear air, the method uses the cloud top as a mediating reference plane from which backward integration proceeds, enabling calibration without direct laser penetration through the cloud layer

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method enables accurate inversion of aerosol extinction coefficients below clouds by iteratively adjusting calibration values, providing clear cloud positions and aerosol distributions with minimal error, even in cloudy conditions.

Implementation Method 1

LIDAR can not only monitor intensity changes of atmospheric aerosols, but also observe the vertical distribution of the atmospheric aerosols

Methodology Applied

Scientific EffectLIDAR: LIDAR

Implementation Method 2

an atmospheric backscattering echo signal power P(Y) at a horizontal range Y received by the LIDAR

Methodology Applied

Scientific EffectScattering: Scattering

Implementation Method 3

CH represents a horizontal atmospheric extinction coefficient (km−1)

Methodology Applied

Scientific EffectExtinction: Absorption (EM radiation)

Data Source

PatentUS20260072176A1Inversion method of aerosol extinction coefficient below clouds by lidar detection

Publication Date: 2026.03.12 HEFEI INSTITUTE OF PHYSICAL SCIENCE CHINESE ACADEMY OF SCIENCES

AI summary

An inversion method of an aerosol extinction coefficient below clouds by Light Detection and Ranging (LIDAR) detection includes: obtaining an aerosol extinction coefficient corresponding to an echo signal of LIDAR in a horizontal direction as a first calibration value EXT1; determining a calibration point altitude at a cloud, and obtaining an atmospheric extinction coefficient corresponding to the calibration point altitude at the cloud base as a second calibration value EXT0; obtaining a second extinction coefficient profile, and obtaining an extinction coefficient at a first altitude X as a second calibration value EXTX, the first altitude X being greater than a blind area altitude; comparing the first calibration value EXT1 with the second calibration value EXTX, adjusting the second calibration value EXT0 when |EXTX−EXT1|>EXT1·δ, performing the obtaining a second extinction coefficient profile based on the adjusted second calibration value EXT0 until |EXTX−EXT1|<EXT1·δ, and outputting the second calibration value EXTX, where δ is a relative error.