Aerosol and Carbon dioxide Detection Lidar (ACDL)
Overview
Guangyao Dai1, Songhua Wu1, Kangwen Sun1, Wenrui Long1, lidar group1 ,Jiqiao Liu2, Weibiao Chen2
1 Faculty of Information Science and Engineering, Ocean University of China, Qingdao, China
2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, China

2023/11/13 @ ESA-ESRIN
1Content

1. Motivation
2. ACDL/DQ-1 introduction
3. Aerosol and cloud optical properties
4. Carbon dioxide column measurements
5. Summary21. Motivation
CO2 and CH4 are the most importantgreenhouse gases responsible for global
warming, currently contributing about+1.3 ℃ to global warming
Aerosol and cloud are the mostimportant masses that cooling theatmosphere with -0.4 ℃.

“The Paris Agreement”
Focus on the global
distributions of the CO2
and aerosol/cloud fromSpace.

IPCC AR63

1. Motivation

HSRL at 532 nm
IPDA at 1572 nm

2006.4-2023.7(Switch off)

Launch: 2022
In-orbit

Mission project:2028-2030

Aeolus-2
Probably 2030

ATLID/EarthCARE(HSRL@355nm)
HSRL at 355
2018-2023(Switch off)

Launch scheduled: 20244

2. ACDL/DQ-1 introduction
SensorObserved object
Global column CO2；

[main Payload]
AerosolandCarbon Global aerosols and clouds profile；

Detection Lidar (ACDL)
Particulate

Global pollutant distribution PM2.5 etc.

Observing

Scanning Polarimeter (POSP)
Directional
Polarization

Camera (DPC)
Environmentaltrace

Aerosols and clouds, PM2.5

Aerosols and clouds, PM2.5

gas

NO2, SO2, O3 etc.
Monitoring Instrument (EMI)
Wide Swath Imaging system Temperature and humidity, aerosols and(WSI)

cloudsSpecification
Orbit

Value705 km,
sun-synchronous orbit

Revisit duration~ 51 days

Weight

2.8 t

lifetime＞ 8 years

52. ACDL/DQ-1 introduction
Specifications
Wavelengths
Laser energy

Parameters532nm, 1064nm and 1572nm；≥130mJ@532nm≥190mJ@1064nm≥40mJ@1572nm

Divergence

50μradStability of the laser 1572nm: 0.6MHZ@10000s
linewidths
1064nm: 5MHz@10000s

Telescope aperture
FOV

20Hz@1572nm (On/Off dual-pulse)
20Hz@532nm and 1064nm (dual-pulse)
1000mm190μrad

HSRL

Iodine cell: OD > 25dB

Receiver channels

532nm HSRL
532nm parallel-polarized
532nm cross-polarized
1064nm aerosol
1572nm CO2PRF➢ The first spaceborne lidar (IPDA) for CO2 detection in the world➢ The first spaceborne Iodine-based HSRL working at 532nm inthe world6

2. ACDL/DQ-1 introductionlevel

Data processing

Data products

FormatLevel 0The observation data obtained by downlinking multi-packet data integrity
inspection and data splicing through the two channels of the satellite.

Raw data

RAW

Level 1A

Process the level 0 aerosol data, obtain the profiles of 532 nm and 1064
nm channels, with the geographic location and height corrected.

Profiles data of 532 nm and 1064
nm channels

HDF5Level 1B

Process the level 0 CO2 data, obtain the profiles of 1572 nm channel, withthe geographic location and height corrected.

Profiles data of 1572 nm channel

HDF5

Level 2A

Attenuated backscatter coefficient with systematic constant correction

Attenuated backscatter coefficient

HDF5

Level 2B

Differential Absorption Optical Depth (DAOD) products

DAOD

HDF5

Level 2C

Cloud and aerosol products including extinction coefficient, backscatter
coefficient, depolarization ratio, AOD, lidar ratio and color ratio

Cloud and aerosol opticalproperties

HDF5

Level 2D

XCO2XCO2

HDF5 72. ACDL/DQ-1 introduction
ACDL/DQ-1 performance assessment:• ACDL/DQ-1 have been operating in-orbit for more than 17 months;• Now about 1 billion laser shots have been emitted in total from the switch-on of ACDL/DQ-1 on 17th May 2022;
Lidar Pulses Count

PulsesRMS=0.41MHz

DateDrops by:~5% (@1064)
Increases by:~5% (@532)

ID No.

Frequency/ MHz

Maximum/ MHz

Minimum/ MHzRMS/ MHz

Allan deviation/ MHz (@10000s)

TML0194

400.02401.49

398.8

0.41

＜0.03

Can be adjusted!

83. Aerosol and cloud optical properties
Specifications

Parameter

wavelength532.024 nm; 1064.490 nm

pulse energy~130 mJ@532 nm; ~190 mJ@1064 nm

repetition rate

20 Hz @ dual-pulse (40 Hz)

Etalon filter bandwidth<20 pmsampling rate

50 MHzvertical resolution

3 m@<7.5 km ; 24 m (8 point average)@>7.5 km

horizontal resolution~ 330 mHigh-spectral-resolution lidar (HSRL) with an iodine vapor absorption
filter (working at 1110 line, bandwidth<2GHz) and polarization
detection➢ 532 nm (cross- and parallel-polarized channels and molecular channel)➢ 1064 nm channel

Dai G, Wu S, Long W, et al. Aerosols and Clouds data processing
and optical properties retrieval algorithms for the spaceborne
ACDL/DQ-1[J]. AMTD, 2023, 2023: 1-20.

Normalized transmission

1.0

spectrum
0.8

1106
0.6

1108

1107
0.4

1109

18786.75

1110
1111

1110 line

0.2

18787.00

18787.25

18787.50

18787.75

18788.00

18788.25

Frequency (cm^-1)

18788.50

18788.75

18789.00

18789.25

9

3. Aerosol and cloud optical properties•Profiling of aerosol and cloud with use of HSRL

•Validation for aerosol and cloud products
103. Aerosol and cloud optical properties: ACDL calibrations
Flow chart of ACDL calibration

3. Aerosol and cloud optical properties: ACDL calibrations
Multi-channel global calibration coefficients of ACDL (June, July 2022)

3. Aerosol and cloud optical properties: ACDL calibrations
Averaged attenuated backscattering coefficients after calibration at 31-35 km altitude versus model results.
(30 July, 2022; 31 October, 2022)

Meng F, Dai G* et al., in preparation.

3. Aerosol and cloud optical properties

Dai G, Wu S, Long W, et al. Aerosols and Clouds data processing
and optical properties retrieval algorithms for the spaceborne
ACDL/DQ-1[J]. AMTD, 2023, 2023: 1-20.

Data products retrieval flowchart

14

3. Aerosol and cloud optical properties(a) Depolarization ratio(b) Backscatter coefficient(a) Depolarization ratio(b) Backscatter coefficient(c) Extinction coefficient(d) Lidar ratio(c) Extinction coefficient(d) Lidar ratio(e) Color ratio(f) Scenario classification(e) Color ratio(f) Scenario classification

Daytime measurement
over Indian Ocean

Nighttime measurement
over Europe and Africa
15

3. Aerosol and cloud optical properties
Backscatter coefficient

Depolarization ratio

Extinction coefficient

Lidar ratio

cloud and aerosol classification

Preliminary results!

Dust event measurement casein Beijing on 8th March, 2023
16

3. Aerosol and cloud optical properties

Depolarization ratio

Canada wildfire on 5 June, 2023

Lidar ratio

17

3. Aerosol and cloud optical properties: validation with CALIOP

Latitude2022-0704-09:43

Longitude

Latitude2022-0704-08:43

Longitude

ACDL and CALIOP simultaneous measurement: 2-3 times higher18

3. Aerosol and cloud optical properties: validation with GB lidars
Santa-Cruz（28.472°N，16.247°W）

With ground-based lidars
in China

LatitudeWith MPLNET
at 02:56 on 9th June 2023

LongitudeACDL
MPLNETACDL

MPLNET

Results from
Lanzhou Univ.
KAUST_Campus（39.103° E，22.305° N）

Qiantao Liu, AMTD, 2023

19

3. Aerosol and cloud optical properties: validation with AERONET/MODIS
With AERONETWith MODIS

All-time
measurements

Night-timemeasurements

4. Carbon dioxide column measurements
Online echo

Echo from ground

Offline echo
Offline monitoringOnline monitoring

Echo from clouds

Echo from ocean

Onlineecho
fromclouds

Online Offline
echo echo
from fromground clouds

Onlineecho
fromocean

Offlineecho
fromground

Offlineecho
fromocean

Flowchart of the XCO2 retrieval

21

4. Carbon dioxide column measurements

ACDL/DQ-1 CO2 performance assessment:• Comparing with passive instruments, the ACDL/DQ-1 isNight-time CO2 measurement in June

capable of providing CO2 measurements both daytime andnighttime;• ACDL/DQ-1 covers the CO2 measurements at high latitudes(from 82°N to 82°S);

All-time CO2 measurement in June22

4. Carbon dioxide column measurements

GOSAT monthly coverage rate: 3-5%

OCO-2 monthly coverage rate: 7-12%

ACDL monthly coverage rate: >80%

ACDL/DQ-1 CO2 measurements:• Monthly coverage rate is 8-10 times higher than passive satellites

23

4. Carbon dioxide column measurements：validation
Sites

Lat/LonInstruments

Xianghe, Hebei

39.75N116.96E

Bruker 125HRs

Additional sites:

Hefei, Anhui

31.91N117.17E

Bruker 125HRs

Edwards, Park Falls, East

Bruker 125HRs

Trout Lake, Karlsruhe etc.

Shanghai
Tsukuba, Japan

31.18N
121.59E
36.051 N
140.121E

Bruker 125HRs

ACDL/DQ-1 CO2 measurements:• R square: 0.934;• RMS: 0.63ppm.

24

5. Summary
1. The first spaceborne lidar for simultaneously observation of CO2 and aerosol based on IPDA and HSRL techniques
are introduced. The first in-orbit demonstration for IPDA and HSRL in space.
2. The procedures for the multi-channel calibration, data pre-processing, and retrieval algorithms are described. The
following properties are calculated based on the data from ACDL/DQ-1: Backscatter coefficient; Depolarization
ratio; Extinction coefficient and Lidar ratio etc.
3. Globally CO2 column concentrations are measured with active instruments (lidars) for the first time, to ourknowledge.
4. Several measurement cases with different scenes (e.g., dust layers, pollutions, smoke, Hunga Tonga sulfate…) arepresented with high temporal and spatial resolution. The observation capability of ACDL/DQ-1 is hence
demonstrated.

5. For the further research, the calibrations and validations for the ACDL data products with collocated ground-basedlidars and satellite active/passive instruments (EarthCARE…) are planned. Thus the international contributions toACDL/DQ-1 are highly recommended and warmly welcome.
Email:
wush@ouc.edu.cn
daiguangyao@ouc.edu.cn

25Thanks

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