1
Lidar Constant C Calibra.on Normalized Rela-ve Backsca3er signal is found by applying the a=erpulse, dead-me, overlap, and range correc-ons to raw lidar signal: The molecular profiles rely on nearby radiosonde profiles. The column-averaged lidar constant C is found using a molecular fiFng algorithm searching for the sta-s-cally best top of aerosol layer. Aeronet AOD : Airport Site (76 m alt.) and Mobile Site (341 m alt.) The airport site was cross-calibrated to the mobile site to increase the number of lidar C calibra-on data points. Solving for Lidar Ex.nc.on A molecular fiFng algorithm finds the top of the aerosol layer, which is combined with the previously found C solves for the column op-cal depth. The Fernald algorithm is then used to find the ex-nc-on profile. Since this inversion is dependent on the molecular fit, the coefficient of varia-on R 2 determines the quality of the data. Only R 2 > 0.5 data are considered. Ascension Island Aeronet AOD (532 nm) Airport Site (sea-level) 0.1 0.2 0.3 0.4 0.5 ARM Site (365 m) 0.1 0.2 0.3 0.4 0.5 Data Fit: y = 0.915x - 0.002 1 to 1 line Results The mountains of Ascension Island and proximity to the ocean encourage orographic li=ing of moist air. Consequently, It is o=en cloudy at the lidar mobile site. Most of the op-cal depth stems from the cloudy boundary layer (0 to 2 km). The al-tude range above the clouds (2 to 5 km) that can contain smoke and other aerosols was most polluted in Oct. 2017, and most pris-ne in late May-early June. During the biomass burning season: The low depolariza-on ra-o indicates that the aerosols are probably smoke. Elevated aerosol layers also occur in Feb and March (example below). The higher depolariza-on ra-os suggest this is dust not smoke Conclusion Aerosols above clouds, between 2 to 5 km, are o=en present at Ascension A new finding is that these are more likely to be dust in late austral summer The ever-present clouds provided a significant challenge in iden-fy good quality lidar data. Collabora-on with the CLARIFY team, the NASA ORACLES lidar team and the new ARM overlap func-on has allowed us to improve our lidar ex-nc-on calcula-on and provide confidence in the results. Introduc.on Ascension Island (8S, 14W) is an ideal loca-on to witness the long- range transport of smoke from African biomass burning and dust. The DOE micropulse lidar provides the only consistent indicator of ver-cal structure during the 17-month-long LASIC campaign. The lidar ex-nc-on profile is derived using an Fernald-based inversion algorithm developed at the University of Miami and is constrained by AERONET-derived aerosol op-cal depth. We compare our lidar inverted ex-nc-on profiles to the CLARIFY EXSCALABAR aircra= in-situ ex-nc-on profile. Aim Comparison between the DOE lidar and in-situ ex-nc-on values Observe aerosol structure evolu-on by month. Be3er understand how to obtain high quality ex-nc-on retrievals from micropulse lidar Acknowledgements Many thanks to DOE ASR DE-SC0013720 LASIC planning grant and DE- SC0018272 for making this research possible. Contact Informa.on Rodrigo Delgadillo: [email protected] Aerosol Ver.cal Structure as Assessed by the Micropulse Lidar upon Ascension Island during the LASIC Campaign Rodrigo Delgadillo, P. Zuidema, P. Muradyan, R. L. Coulter, S. J. Abel, C. Fox, R. A. Ferrare, S. P. Burton Univ. of Miami/RSMAS, Miami, FL DOE Argonne Ntnl Lab UK Met Office NASA Langley NRB [Counts km 2 / 7 J 7 s] 0 0.2 0.4 Range [km] 0 5 10 08:21:36 NRB max: 1.06 R 2 : 0.63 S NRB (z )= C (β a (z )+ β m (z ))e -2(a (z )+m (z )) MPL Particle Extinction 18:00 04 Mar 2017 20:15 22:30 00:45 03:00 05:15 07:30 09:45 12:00 05 Mar 2017 Altitude km 0 1 2 3 4 5 km -1 0 0.06 0.12 0.18 0.24 60.3 MPL Linear Depolarization Ratio 18:00 04 Mar 2017 20:15 22:30 00:45 03:00 05:15 07:30 09:45 12:00 05 Mar 2017 UTC Altitude km 0 1 2 3 4 5 0 0.03 0.06 0.09 0.12 60.15 R 2 > 0.5 Ceilometer cloud base in red MPL Particle Extinction 18:00 14 Aug 2016 21:45 01:30 05:15 09:00 12:45 16:30 20:15 00:00 16 Aug 2016 Altitude km 0 1 2 3 4 5 km -1 0 0.06 0.12 0.18 0.24 60.3 MPL Linear Depolarization Ratio 18:00 14 Aug 2016 21:45 01:30 05:15 09:00 12:45 16:30 20:15 00:00 16 Aug 2016 UTC Altitude km 0 1 2 3 4 5 0 0.03 0.06 0.09 0.12 60.15 R 2 > 0.5 Ceilometer cloud base in red Comparison with CLARIFY In-situ Ex.nc.on (EXSCALABAR) MPL ex-nc-on for 15 min average of the raw lidar data: The post-deployment overlap calibra-on done by ARM at the SGP site differs substan-ally from the pre-deployment calibra-on done by the MPL manufacturer SigmaSpace. The new overlap places less weight within the boundary layer, reducing those ex-nc-ons. The new ex-nc-on profiles above 2km have ver-cal structures that agree with those from the aircra=. Correc-ng the derived column-averaged lidar ra-o to be 65/sr, the mean lidar ra-o of free-tropospheric smoke at 530 nm derived by the NASA High Spectral Resolu-on Lidar 2 during ORACLES Sept 2016, brings the MPL-retrieved values into approximate agreement with the in-situ ex-nc-on. Integrated Extinction for Entire Campaign with 3 day running average 10 Jul 2016 25 9 Aug 2016 24 8 Sep 2016 23 8 Oct 2016 23 7 Nov 2016 22 7 Dec 2016 22 6 Jan 2017 21 5 Feb 2017 20 7 Mar 2017 22 6 Apr 2017 21 6 May 2017 21 5 Jun 2017 20 5 Jul 2017 20 4 Aug 2017 19 3 Sep 2017 18 3 Oct 2017 18 2 Nov 2017 UTC Integrated Extinction 0 0.05 0.1 0.15 0.2 0.25 0.3 od1: integrated from 0 to 2 km od2: integrated from 2 to 5 km Boundary layer Lower free troposphere Cloudy profiles excluded by fiFng algoritm MPL: 25-Aug-2017 14:30 Aircraft: 25-Aug-2017 14:17 to 14:31 Extinction [Mm -1 ] 0 100 200 300 400 500 Altitude [km] 0 1 2 3 4 5 6 2016 Sigma Space Overlap (aod: 0.29, R2: 0.56, LR: 18.07 sr -1 ) 2018 ARM Overlap (aod: 0.09, R2: 0.49, LR: 13.54 sr -1 ) Aircraft RH 405 (aod: 0.21) Aircraft RH 660 (aod: 0.11) LR Adjusted MPL (65 sr -1 ) MPL: 01-Sep-2017 13:45 Aircraft: 01-Sep-2017 13:26 to 13:48 Extinction [Mm -1 ] 0 100 200 300 400 500 Altitude [km] 0 1 2 3 4 5 6 2016 Sigma Space Overlap (aod: 0.72, R2: 0.19, LR: 13.65 sr -1 ) 2018 ARM Overlap (aod: 0.38, R2: 0.24, LR: 25.04 sr -1 ) Aircraft RH 405 (aod: 0.53) Aircraft RH 660 (aod: 0.28) LR Adjusted MPL (65 sr -1 )

Aerosol Ver.cal Structure as Assessed by the Micropulse Lidar … · 2018. 7. 5. · NRB max: 1.22 R2: 0.57 NRB [Counts km2/ 7J7s] 0 0.2 0.4 Range [km] 0 5 10 18:11:04 NRB max: 1.25

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Page 1: Aerosol Ver.cal Structure as Assessed by the Micropulse Lidar … · 2018. 7. 5. · NRB max: 1.22 R2: 0.57 NRB [Counts km2/ 7J7s] 0 0.2 0.4 Range [km] 0 5 10 18:11:04 NRB max: 1.25

LidarConstantCCalibra.on•  NormalizedRela-veBacksca3ersignalisfoundbyapplyingthe

a=erpulse,dead-me,overlap,andrangecorrec-onstorawlidarsignal:

•  Themolecularprofilesrelyonnearbyradiosondeprofiles.•  Thecolumn-averagedlidarconstantCisfoundusingamolecular

fiFngalgorithmsearchingforthesta-s-callybesttopofaerosollayer.

•  AeronetAOD:AirportSite(76malt.)andMobileSite(341malt.)•  Theairportsitewascross-calibratedtothemobilesitetoincrease

thenumberoflidarCcalibra-ondatapoints.SolvingforLidarEx.nc.on•  AmolecularfiFngalgorithmfindsthetopoftheaerosollayer,

whichiscombinedwiththepreviouslyfoundCsolvesforthecolumnop-caldepth.

•  TheFernaldalgorithmisthenusedtofindtheex-nc-onprofile.•  Sincethisinversionisdependentonthemolecularfit,the

coefficientofvaria-onR2determinesthequalityofthedata.•  OnlyR2>0.5dataareconsidered.

Ascension Island Aeronet AOD (532 nm)

Airport Site (sea-level)0.1 0.2 0.3 0.4 0.5

AR

M S

ite (

365 m

)

0.1

0.2

0.3

0.4

0.5

DataFit: y = 0.915x - 0.0021 to 1 line

Results•  ThemountainsofAscensionIslandandproximitytotheocean

encourageorographicli=ingofmoistair.•  Consequently,Itiso=encloudyatthelidarmobilesite.•  Mostoftheop-caldepthstemsfromthecloudyboundarylayer(0

to2km).Theal-tuderangeabovetheclouds(2to5km)thatcancontainsmokeandotheraerosolswasmostpollutedinOct.2017,andmostpris-neinlateMay-earlyJune.

Duringthebiomassburningseason:

•  Thelowdepolariza-onra-oindicatesthattheaerosolsareprobablysmoke.

ElevatedaerosollayersalsooccurinFebandMarch(examplebelow).Thehigherdepolariza-onra-ossuggestthisisdustnotsmoke

Conclusion•  Aerosolsaboveclouds,between2to5km,areo=enpresentat

Ascension•  Anewfindingisthatthesearemorelikelytobedustinlateaustral

summer•  Theever-presentcloudsprovidedasignificantchallengeiniden-fy

goodqualitylidardata.•  Collabora-onwiththeCLARIFYteam,theNASAORACLESlidarteam

andthenewARMoverlapfunc-onhasallowedustoimproveourlidarex-nc-oncalcula-onandprovideconfidenceintheresults.

Introduc.on•  AscensionIsland(8S,14W)isanidealloca-ontowitnessthelong-

rangetransportofsmokefromAfricanbiomassburninganddust.•  TheDOEmicropulselidarprovidestheonlyconsistentindicatorof

ver-calstructureduringthe17-month-longLASICcampaign.•  Thelidarex-nc-onprofileisderivedusinganFernald-based

inversionalgorithmdevelopedattheUniversityofMiamiandisconstrainedbyAERONET-derivedaerosolop-caldepth.

•  Wecompareourlidarinvertedex-nc-onprofilestotheCLARIFYEXSCALABARaircra=in-situex-nc-onprofile.

Aim•  ComparisonbetweentheDOElidarandin-situex-nc-onvalues•  Observeaerosolstructureevolu-onbymonth.•  Be3erunderstandhowtoobtainhighqualityex-nc-onretrievals

frommicropulselidar

AcknowledgementsManythankstoDOEASRDE-SC0013720LASICplanninggrantandDE-SC0018272formakingthisresearchpossible.

ContactInforma.onRodrigoDelgadillo:[email protected]

AerosolVer.calStructureasAssessedbytheMicropulseLidaruponAscensionIslandduringtheLASICCampaign

RodrigoDelgadillo,P.Zuidema,P.Muradyan,R.L.Coulter,S.J.Abel,C.Fox,R.A.Ferrare,S.P.BurtonUniv.ofMiami/RSMAS,Miami,FLDOEArgonneNtnlLabUKMetOfficeNASALangley

NRB [Counts km2/ 7J7s]

0 0.2 0.4

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km]

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08:13:50NRB max: 1.07

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NRB [Counts km2/ 7J7s]

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km]

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08:21:36NRB max: 1.06

R2: 0.63

NRB [Counts km2/ 7J7s]

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km]

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08:26:16NRB max: 1.08

R2: 0.60

NRB [Counts km2/ 7J7s]

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km]

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10:02:25NRB max: 0.94

R2: 0.61

NRB [Counts km2/ 7J7s]

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17:01:02NRB max: 1.08

R2: 0.52

NRB [Counts km2/ 7J7s]

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R2: 0.51

NRB [Counts km2/ 7J7s]

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R2: 0.61

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R2: 0.61

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R2: 0.60

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R2: 0.53

NRB [Counts km2/ 7J7s]

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17:33:50NRB max: 1.29

R2: 0.57

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km]

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R2: 0.68

NRB [Counts km2/ 7J7s]

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NRB [Counts km2/ 7J7s]

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R2: 0.70

NRB [Counts km2/ 7J7s]

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km]

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R2: 0.56

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km]

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R2: 0.56

18-Aug-2017

SNRB(z) = C(�a(z) + �m(z))e�2(⌧a(z)+⌧m(z))

MPL Particle Extinction

18:00

04 Mar 2017

20:15 22:30 00:45 03:00 05:15 07:30 09:45 12:00

05 Mar 2017

Altitu

de

km

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3

4

5

km

-1 0

0.06

0.12

0.18

0.24

60.3

MPL Linear Depolarization Ratio

18:00

04 Mar 2017

20:15 22:30 00:45 03:00 05:15 07:30 09:45 12:00

05 Mar 2017UTC

Altitu

de

km

0

1

2

3

4

5

0

0.03

0.06

0.09

0.12

60.15

R2 > 0.5

Ceilometer cloud base in red

MPL Particle Extinction

18:0014 Aug 2016

21:45 01:30 05:15 09:00 12:45 16:30 20:15 00:0016 Aug 2016

Alti

tud

ekm

0

1

2

3

4

5

km-1

0

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60.3

MPL Linear Depolarization Ratio

18:0014 Aug 2016

21:45 01:30 05:15 09:00 12:45 16:30 20:15 00:0016 Aug 2016UTC

Alti

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ekm

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3

4

5

0

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60.15

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Ceilometer cloud base in red

ComparisonwithCLARIFYIn-situEx.nc.on(EXSCALABAR)•  MPLex-nc-onfor15minaverageoftherawlidardata:

•  Thepost-deploymentoverlapcalibra-ondonebyARMattheSGPsitedifferssubstan-allyfromthepre-deploymentcalibra-ondonebytheMPLmanufacturerSigmaSpace.Thenewoverlapplaceslessweightwithintheboundarylayer,reducingthoseex-nc-ons.

•  Thenewex-nc-onprofilesabove2kmhavever-calstructuresthatagreewiththosefromtheaircra=.

•  Correc-ngthederivedcolumn-averagedlidarra-otobe65/sr,themeanlidarra-ooffree-troposphericsmokeat530nmderivedbytheNASAHighSpectralResolu-onLidar2duringORACLESSept2016,bringstheMPL-retrievedvaluesintoapproximateagreementwiththein-situex-nc-on.

Integrated Extinction for Entire Campaign with 3 day running average

10Jul

2016

25 9Aug2016

24 8Sep2016

23 8Oct

2016

23 7Nov2016

22 7Dec2016

22 6Jan

2017

21 5Feb2017

20 7Mar2017

22 6Apr

2017

21 6May2017

21 5Jun

2017

20 5Jul

2017

20 4Aug2017

19 3Sep2017

18 3Oct

2017

18 2Nov2017

UTCIn

teg

rate

d E

xtin

ctio

n

0

0.05

0.1

0.15

0.2

0.25

0.3

od1: integrated from 0 to 2 kmod2: integrated from 2 to 5 km

Boundarylayer

Lowerfreetroposphere

CloudyprofilesexcludedbyfiFngalgoritm

MPL: 25-Aug-2017 14:30Aircraft: 25-Aug-2017 14:17 to 14:31

Extinction [Mm-1]

0 100 200 300 400 500

Alti

tude [km

]

0

1

2

3

4

5

6

2016 Sigma Space Overlap (aod: 0.29, R2: 0.56, LR: 18.07 sr-1)

2018 ARM Overlap (aod: 0.09, R2: 0.49, LR: 13.54 sr-1)Aircraft RH 405 (aod: 0.21)Aircraft RH 660 (aod: 0.11)

LR Adjusted MPL (65 sr-1)

MPL: 01-Sep-2017 13:45Aircraft: 01-Sep-2017 13:26 to 13:48

Extinction [Mm-1]

0 100 200 300 400 500

Alti

tude [km

]

0

1

2

3

4

5

6

2016 Sigma Space Overlap (aod: 0.72, R2: 0.19, LR: 13.65 sr-1)

2018 ARM Overlap (aod: 0.38, R2: 0.24, LR: 25.04 sr-1)Aircraft RH 405 (aod: 0.53)Aircraft RH 660 (aod: 0.28)

LR Adjusted MPL (65 sr-1)