# Atmospheric backscatter profiling lidar *methodologies* Elastic backscatter lidar fires laser pulses (typically 532/1064 nm) and resolves the return as a function of altitude to retrieve range-resolved profiles of aerosol and cloud attenuated backscatter and extinction. Acquisition: range-gated elastic backscatter vs altitude. Retrieval: aerosol/cloud vertical structure, optical depth, depolarisation. Example instruments: CALIPSO/CALIOP, EarthCARE/ATLID. ## Specifications - **family**: LiDAR - **entity type**: methodology - **last verified date**: 2026-06-05 - **verified by**: agency-doc - **claim status**: unclaimed - **attributes**: {"family":"LiDAR","summary":"Elastic backscatter lidar fires laser pulses (typically 532/1064 nm) and resolves the return as a function of altitude to retrieve range-resolved profiles of aerosol and cloud attenuated backscatter and extinction. Acquisition: range-gated elastic backscatter vs altitude. Retrieval: aerosol/cloud vertical structure, optical depth, depolarisation. Example instruments: CALIPSO/CALIOP, EarthCARE/ATLID."} - **technology**: lidar ## Editorial Atmospheric backscatter profiling lidar fires short laser pulses and records the range-gated return signal as a function of altitude, producing vertical profiles of aerosol and cloud attenuated backscatter and extinction across the troposphere and lower stratosphere. The method relies on elastic scattering of photons from aerosol particles and molecules, with depolarisation channels capable of distinguishing liquid water droplets from non-spherical ice crystals and dust. Spaceborne implementations have operated at wavelengths including 532 nm, 1064 nm, and 355 nm. CALIPSO/CALIOP established a reference architecture with a dual-wavelength, three-channel receiver achieving 30 m vertical and 333 m horizontal resolution at a 705 km orbit, measuring from the surface to 40 km altitude.[^s-eoportal-calipso][^s-ncbi-caliop-cal-v4] EarthCARE/ATLID extends the technique with a 355 nm high-spectral-resolution lidar (HSRL) that separates molecular and particulate backscatter without relying on assumed aerosol models, improving extinction retrieval accuracy at 100 m vertical resolution to 20 km.[^s-amt-atlid-a-pro][^s-eoportal-earthcare] China's ACDL on DQ-1 combines a 532 nm HSRL and polarisation channel with a 1064 nm elastic channel for coincident aerosol and cloud profiling.[^s-amt-acdl-calibration] The ISS-hosted CATS demonstrated three-wavelength backscatter (355/532/1064 nm) with 532 nm HSRL from February 2015 to October 2017, validating HSRL retrievals from a low-inclination orbit.[^s-cats-gsfc] ICESat/GLAS carried a dual-purpose design: primary ice-sheet altimetry at 1064 nm, with coincident 1064 and 532 nm backscatter channels producing cloud and aerosol boundary and extinction data products.[^s-nsidc-glas-backscatter][^s-researchgate-glas-initial] Aeolus/ALADIN produces aerosol backscatter at 355 nm through its Mie-channel Fizeau interferometer as a co-product alongside its primary Doppler wind retrieval.[^s-esa-aladin-overview] Core data products include attenuated backscatter coefficient profiles, particulate extinction, column optical depth, aerosol layer top and base heights, cloud thermodynamic phase, and aerosol subtype classifications. These products feed air-quality monitoring, climate radiation budget assessments, and numerical weather prediction assimilation. ## Sources - [s-eoportal-calipso] | CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) - eoPortal | https://www.eoportal.org/satellite-missions/calipso | tier=community | accessed=2026-06-05 CALIOP dual-wavelength 532/1064 nm elastic backscatter, three-channel receiver, 30 m vertical resolution, 333 m horizontal resolution, 705 km orbit, surface to 40 km altitude - [s-ncbi-caliop-cal-v4] | CALIPSO Lidar Calibration at 532 nm: Version 4 Nighttime Algorithm - PMC | https://pmc.ncbi.nlm.nih.gov/articles/PMC7816828/ | tier=peer-reviewed | accessed=2026-06-05 Peer-reviewed calibration paper confirming 532 nm elastic backscatter measurement principle and attenuated backscatter products - [s-esa-aladin-overview] | ALADIN - ESA Earth Online | https://earth.esa.int/eogateway/instruments/aladin | tier=agency-doc | accessed=2026-06-05 ALADIN 355 nm direct-detection Doppler wind lidar; Mie channel (Fizeau interferometer) produces aerosol backscatter co-product - [s-amt-acdl-calibration] | ACDL/DQ-1 calibration algorithms Part 1: 532 nm polarization and HSRL channel - AMT 2025 | https://amt.copernicus.org/articles/18/2021/2025/ | tier=peer-reviewed | accessed=2026-06-05 Peer-reviewed; confirms ACDL 532 nm HSRL + polarization + 1064 nm elastic channel for atmospheric backscatter profiling on DQ-1 - [s-amt-atlid-a-pro] | The EarthCARE lidar cloud and aerosol profile processor (A-PRO) - AMT 2024 | https://amt.copernicus.org/articles/17/5301/2024/ | tier=peer-reviewed | accessed=2026-06-05 Peer-reviewed; ATLID 355 nm HSRL; retrieves particulate attenuated backscatter, Rayleigh molecular backscatter, perpendicular backscatter; 100 m vertical resolution to 20 km - [s-nsidc-glas-backscatter] | GLAS/ICESat L1B Global Backscatter Data - NSIDC | https://nsidc.org/data/gla07/versions/18 | tier=agency-doc | accessed=2026-06-05 ICESat/GLAS L1B backscatter product at 1064 nm and 532 nm; atmospheric backscatter profiling alongside primary altimetry - [s-researchgate-glas-initial] | GLAS on ICESat: Initial Science Measurement Performance - peer-reviewed | https://www.researchgate.net/publication/23976855_Geoscience_Laser_Altimeter_System_GLAS_on_the_ICESat_Mission_Initial_Science_Measurement_Performance | tier=peer-reviewed | accessed=2026-06-05 Confirms GLAS 1064 nm primary altimetry + 1064/532 nm atmospheric backscatter; dual-purpose design; cloud/aerosol layer boundary and extinction data products - [s-cats-gsfc] | Cloud-Aerosol Transport System (CATS) - NASA GSFC | https://cats.gsfc.nasa.gov/ | tier=agency-doc | accessed=2026-06-05 CATS: three-wavelength 1064/532/355 nm elastic backscatter + HSRL at 532 nm on ISS JEM-EF, Feb 2015 - Oct 2017 - [s-eoportal-earthcare] | EarthCARE - eoPortal | https://www.eoportal.org/satellite-missions/earthcare | tier=community | accessed=2026-06-05 EarthCARE/ATLID mission profile, ESA-JAXA, launched May 2024 --- Source: https://eo-atlas.org/methodologies/lidar-atmospheric-backscatter Maintainer: SpectraWorks B.V. 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