Abstract

The retrieval of the aerosol optical thickness (AOT) from remotely-sensed data relies on the adopted aerosol model. However, the method of this technique has been rather limited because of the high variability of the surface albedo, in addition to the spatial variability in the aerosol properties over the land surfaces. To overcome unsolved problems, we proposed a method for the visibility-derived AOT estimation from SKYNET-based measurement and daytime satellite images with a custom aerosol model over the Chiba area (35.62° N, 140.10° E), which is located in the greater Tokyo metropolitan area in Japan. Different from conventionally-used aerosol models for the boundary layer, we created a custom aerosol model by using sky-radiometer observation data of aerosol volume size distribution and refractive indices, coupled with spectral response functions (SPFs) of satellite visible bands to alleviate the wide range of path-scattered radiance. We utilized the radiative transfer code 6S to implement the radiative transfer calculation based on the created custom aerosol model. The concurrent data from ground-based measurement are used in the radiative analysis, namely the temporal variation of AOT from SKYNET. The radiative estimation conducted under clear-sky conditions with minimum aerosol loading is used for the determination of the surface albedo, so that the 6S simulation yields a well-defined relation between total radiance and surface albedo. We made look-up tables (LUTs) pixel-by-pixel over the Chiba area for the custom aerosol model to retrieve the satellite AOT distribution based on the surface albedo. Therefore, such a reference of surface albedo generated from clear-sky conditions, in turn, can be employed to retrieve the spatial distribution of AOT on both clear and relatively turbid days. The value for the AOTs retrieved using the custom aerosol model is found to be stable than conventionally-used typical aerosol models, indicating that our method yields substantially better performance.

Highlights

  • Atmospheric aerosol has a pivotal role in both air pollution and radiation budget studies [1,2,3]

  • High spatial resolution satellite images can be useful for obtaining aerosol optical thickness (AOT) distribution in wide regions, the lack of accurate knowledge on the optical characteristics of surface reflectance often leads to uncertainties in the retrieval of AOTs [11]

  • We described the custom aerosol model for the extraction of the AOT distribInuttihoinssstaurdouy,nwd ethdeesCchriibbeadatrheea cfruosmtomskaye-rraodsoiol mmeotdeerlwfoitrhthseufefixctireancttiaocncuofratchye

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Summary

Introduction

Atmospheric aerosol has a pivotal role in both air pollution and radiation budget studies [1,2,3]. The variability characterized by such measurements is strongly site-specific and the spatial coverage offered by ground-based networks is not necessarily sufficient to evaluate the variability at a scale that is significant for the climate In this regard, satellite-based measurements have the advantage of broad and continuous observation, with the ability to collect large-range aerosol information and obtain their yearly spatiotemporal distributions [25]. This observation site is located on the east side of Tokyo Bay, surrounded by urban or industrial districts. Since the Atmosphere 2021, 12, 1144 Atmosphere 2021, 12, 1144 properties and monthly sampling of aerosol particles have been conducted at CEReS3.oTf h21is observation site is located on the east side of Tokyo Bay, surrounded by urban or indus‐ trial districts. Hariema.aHwiamria-8wiasroi‐n8eisofoJnaepoafnJ’sapnaenw’sgneeowstagteioonstaartyiosnaaterlylisteast‐ tehlalitthesasthbaetenhaospbeeraetnedopbeyrtahteedJabpyanthMe eJatepoarnolMogeitceaolrAogloegniccyal(JAMgAen) csyin(cJeMJuAl)ys2i0n1c5e [J3u6l]y. 2T0h1e5 A[3d6v]a. nTcheedAHdimvaanwcaerdi IHmiamgaewr (aAriHIIm) saegnesro(rAoHnbI)oasrednsHoirmoanwbaorair-d8 iHs simupaewriaorri‐t8o icsonsuvpenetriioonratlo icmoangveernst,ioansailt ihmaasgmeros,reasviitshibalsemanodrenveisairb-lienfarnadrendeawra‐ivneflreanregdthwbaavnedlesn, gththerbeabnydse,ntahbelrienbgy heingahbelri-ndgimhiegnhseior‐ndailmteernrseisotnriaallteenrrveisrtorniaml eennvt imroonnmiteonritnmg o[3n7it]o. rAinsga[g3e7o].sAtastiaongaeroystsaattieolnliatery, Hhs3ia5igmt.h8ela0law0itbekao,mrviH-e8himitrgheahecwoaerabqdrousiv‐a8tehtortehresceauoetrrqfdaausrcoaettuhoanerndasdut1aar4tfrm0ao◦cuoenEsapdn[h31de84r]0ae.°tomEIfto[t3ahsp8les]ho.eeIatrhreatahlsosfoaatthhalaoepswpearaoslropxtwhaimtaisaatpltaaiortpeinapslro3rol5eux,s8itomi0ol0uankttiiomoofnn 5o0f05–0200–0200m00bmutbisuctaips acbalpeaobflemoofnmitoorninitgoraienrgosaoelrvoasorilavtiaorniastaiot nthseaht itghhe theimghpoteraml preosroallurteiosno‐ AoofttflEtAehrfruereHraebeHr2teqrseqiiI.dutoteI5duhIsneInsseaembnaneountnoatntrtictsh0tfnnbhs0hod.i2ddoi4.isrfat4.sr7saao5toss7,tsasroutt,mnat0u,ontc,uM0b.h1dibh5.1done50eoy1O0xaya1,,famJrts,D,omawarrdwarMdpainInientSctandehtOhtd,nfhfiofefo0ttsDioo0ahhcs.rJ6scr.rIueae6satSue4pshta4ta,ishaeeμtaneteμdedel[hnmfdl3fmlvoieluf9mtaiaurmetal]armenla.,lanedla,nwtdAiaadvaniwddintasga[sliia3aylssonkeacyp9skntopuo[]paouom4.ps[ngflpn4se0Ailepee0eidt]Hetsh.ddr]aohd.tfiecTrfiomeftTeonohHhtdrdhmhdeareeatineewahwmtypsphytesptpaariateipttrrrorimewohmeieoarcc-adcdectae8ttertdehhdririawadiiiimeeau‐slamtu8liirotrdtavtirearehibhvgieesegsrsoeeetspetetoehfsphrctsorfaearaoteovnvaonatnofasasmnaftsscbtemvtifsiteahlsoeoafhafteoerrsiufntrberlrsupeesanviepfrinshelbcramiihivcetonitmtvyletiiriumgioiiosrituoslciiynonaibconltbfactholf(ficloetS(romfeeiosSorRonbmorrRlbmunosFraelaFuace.scnw)nht.)crctdfhitd-hoforiEsemoosarnmarcnldcotoreohoetitrwonhanhnreen--ee‐‐ ttihonesferobmandthsetolaenxdtrsaucrtftahcee.inHfoimrmaawtiaorni-8peimrtiangeentdtaotathperodviriedcetdscbayttCerEinRgeSofwsaoslaursreadd.iaTthioen CfrEoRmeSthdeatlaanadresguernfaecrea.teHdimbyaawpaprliy‐8inigmfaugrethdeartgaepormoevtirdicedcobryreCctEioRnesStowJaMs Ausdedat.aTahiemCinEgRaetS pdoatteanatirael gaepnpelircaatetidonbytoalpapnldyisnugrffaucrethoebrsgeervoamtieotnrisc, cwohrriechctiroenqsuitroeJhMigAhdgaetoaloacimatiinogn aatccpuo-‐ rtaecnyti[a4l1a–p4p3]l.icTaatibolne 1toplraonvdidseusrfthaceeroelbesvearnvtatdioetnasi,lswohnicthhereuqsueidreclheiagrh-sgkeyotleosctaitmioangaecscfurroamcy A[4H1I–4o3b]s.eTrvabatleio1nsp.rovides the relevant details on the used clear‐sky test images from AHI observations

Landsat-8 OLI
Custom Aerosol Model
Radiative Transfer Handled by 6S
Process of AOT Retrieval
Reference of Surface Albedo
Spatiotemporal Analysis and Characteristics of AOT Distribution
A Case Analysis of Landsat-8 OLI
Findings
Conclusions
Full Text
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