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Vol . 22S IJOURNALOFTROPICALMETEOROLOGYJul y20 1 6
Arti c leID :1 006-
87 75 (20 1 6 )S I
-
0 067-
11
HAZE-TO-FOGTRANSFORMATIONDURINGALONGLASTING,LOW
VISIBILITYEPISODEINNANJING
ZHANGShu-
ting(张舒婷 ) ,
NIUSheng-
jie(牛生杰 )
(Key
Labo ra tory of Meteo ro logi calD isas ter
,M inis tryo fEdu cat io n/ J oint Interna t iona lRes earch Labo rato r
yo f C limate
and E nv ironmen tCh ange/Co l labora ti veInn ovat ionCen teronForecast andEva luat ionofMe teo ro log icalDis aster s
,
Nanj ingUn i
v ers i tyof In fo rmat
i onSc ienceandTec hno logy,Nanj ing2 1 0044China
)
Abstract :Haze -
to-
fog tran sfo rmat io nduri
ng
a lon
g la sting , l
owvisib i l i
tyep i
sodewasexam inedus ingtheobs ervat
i on s
fromacomprehens iv efie ldcampaigncon duct
ed inNanj i ng ,Chi naduring4
-
9Decemb er20 1 3 . Inth isep i sode,haze
wastrans formed intofogand the fog
lastedfo rdozensofhour s.Theimpac t sofme teorolog icalfac torssuchas w ind
,
t emperat
ur e(T
) andrel at i
veh umid ity (RH
) onhaze , tran sit i onandfogduring thisepi
sodewere inves t igated .Resul tsr e?
vea led s i
gn i fi cant di fferencesbetween hazeandfo
gdays ,dueto the ird ifferen tfo rmationm echani sms .Compari sonwas
madefo rbou ndary
-
layer cond it ionsduringhazydays ,haze
-
to-
fog
day sand foggydays .D ist ribu ti onsofw indspeed
and w ind di re ct ionaswe ll as syno
pticweathercondi ti ons aroundNanj in
ghadde term inati veimpactsontheoccur rences
and charac terist icso f hazeandfog
. Weakeneds ou ther l
yw ind insou thern Nanj i ng
resu lted inhi
ghconcentrat
ionofpo l
?
lutan ts,andh azeeventsoccurred f
requ ent lyduring thestudyperiod .Th ew
inds
peedwas les sthan 1m s
'
in thehaze
event,wh ichresu l tedi na stab leatmo s
phericcond i tionand we akd ispersiono fth e
pol lu tan ts .Thehe i
gh tof th etem
per
?
atureinvers ionwasabout400mduri ng
theperiod
.Th e invers ionin tens itywasweakandthetempe rature
-
d ifference
w as4°
Ckm'
1
orle ss inhaze ,wh i lethe i
nvers ionwass tronger,andtemperature
-
differencewasabout6^ 1kin*
1
,ap?
proach in
g th einvers ionl a
yerin tensi
t
y i nth e fogevent .Hazeeventi sstrong lyin fluenced by
amb ien tRH .RHval ues in?
creased, wh ich res ul ted inhazeda
ysev ident ly increased
,sugges ti ng
that ani ncreasi ng
frac t ionof haze eventsbecaus ed
byhygros cop ic
grow th ofaeros ol s,ra th er th ansimp
l yby h i gha eroso ll oading
.When RHwasab ove9 0% ,hazeaero so ls
startedtobetrans fo rm edfromhazetofog
.Th isstudy
ca ll sfo rmoreefforts to contro lem i ss ionstop
reventhazeevents
inthereg
ion .
Keyw
o rds :h aze;fog ;
tran sformat ion;met eorol og
ica le lement s
CLC number :P427 .2Documentcode :A
do i :
1 0. 1 6 5 55 /j.1 00 6
-8 77 5 .2 0 1 6 . S1 .007
1INTRODUCTIONYangtzeR iverDel ta (
YRD)ha ssufferedfromseve re
po llution scausedb yh i ghconcen trationsofaerosol
par-
Low vis ibi li t
ycau sedby
fogorsevere hazecanbe tide s re sul tedfromem i s sions fromfo ss i l fueland
aheavyburdenfora ir transpor
tand roadtraffic .Po llu-biomas sburning ,transportationandoth ercombu stion
tantpar tic leconcentra tionsdur inghazeorfogeventssource s (
Cheneta l .
[5
]
).Conc entration sofaerosol
par ti-
canb es everal times,orevenadozentimes
,highe rthan
c lesgreatlyexceeded therecent lyrevisedambi enta ir
those dur ingnorma lweathe rs,and
po l lu tantpar tic les inqua
l itys
tandardofChinaforPMZ5 andwereatleas t1 0
thea irthreatenthehea lthofhumansandotherl iv ing t imesthosemeasuredinea ste rnUS .Thema incauseof
things in manyregionsintheworld
(Jacquel ineetal .
[
l
]
;hazei satmospheri cae roso lpartic le s
,andfogcouldde-
Poschl[2
]
).Duetofa stdeve lopment inChin ainrecentcreasePM
2.
5andPM 1 0ne artheground(
Fane tal .
E6
]
).
years ,China'
sregiona lhaze i nurb anare ashas in-Aeroso lsin theenvi ronmentaredecidedbypar
ti cle
c rea seds i
gni ficantl
y ,wh i lethe re isadec re as ing
trend s ize,
shapeandchem ica lcompos i t ion(
Okadae tal.
[7]
).
of foggydaysinCh i na(
T iee ta l.
[
3]
;Fueta l .
[
4J
).TheAtmo spher icfinepart icul atesplayama
jorrol eina ir
pollut ion (Heeta l .
[8]
).
Recei ved2 0 1 5-
0 7-
2 8;Revi sed20 16
-
03-
1 5;Accep
tedTheformationofhazei sc losel
yl inkedtome teoro-
20 1 6-07 -
1 5logica landatmosp
he ri ccondi t ions(La iandS eque ira
[9]
;
Foundationi tem :Nat iona lNatu ra lScienceFoun dati onof Ch i
-L ieta l.
[l 0
1
).Atmo spher ichazeisma in lygatheredin the
na(4 1 275 1 5 1,4 1 3 75 1 38 ) ;Gr aduateS tudentInnovat ionP lanbounda r
ylayer
,sow ind, temperatureandhumidi t
ybe-
for theUni vers iti eso f J ian
gsuProv ince (CXZZ 1 3
-
0 5 1 4 ) ;apro -
l〇w850hPaa re themos timportantfactors .Whenthe re
je ctfundedby thePrio r
ity Academ icPr ogramDeve lopm
en tofisaninver siolllaye r inthei〇w ertroposphe re ,thea tmo-
J iang suH igherEducat ion In st itut ion s,
?.
^^A,?
,,,.
^j.
j?
,sphe re ismas tables tate,whi chwouldl imi tvert i ca l
B iography :ZHANGShu-
ting,Ph .D .cand idate
,p rimari
l
yun
-
. .
^ tr , n^,,mi 、
dertak i ng
res earchon atmosphericenvironment .d lSPerS 10nof
Pol lutants(P lheeta l
[U
,
;Roa cheta l -
[' 2
1
)-
Correspondingauthor:ZHANGShu-
t ing,e
-ma il :va ri ationofhazedays isma in l
yre lat edto
zhangst1 0@nuis t .edu . cnaeroso lpo l lutioncondi tionandtochange sofsurround
-
6 8JournalofTrop i calM eteo ro logyVo l. 22
ingenvi ronmen t .Ca lmcond idonmwinte r isop
t imal
2DATAANDMETHODSforhazeto oc cur .High
-
pressuresys temi s thema insyn
?
opt icsys teminwhichha zec anoccur(Wange tal .
1
1 31
).2 . 1Dataands iteinfo
rmat ion
Themainrea soni sthatatmosphe ricstratif
ication issta
-TheYRDh adbe enundergoingrapiddevelopment
bleand theinversionlayer
i smuchth i cke rinwinte r;a sduringthela stthreedec ades .Nan
jing
i same gaci ty
i n
are sul t,po llu tantsaremuche as iertogather .Incon- theYRDwi thhi
ghpopu
l at iondensi ty andawel
l-deve l
-
tra st, inwe athersys tem sofcyc loneandea ste r lyb el t
,opede conomy.Urbanizationh asbrought
grea tstres sto
hazedays occurrarely .l oca lenvironmentan dhaze-
rel ateddi sastersh appened
SixChine semegac it i es su fferedfromcon tinuous-frequently .Thefie ldstudy
focusingonphys
i cscharac-
lydecreas ing vi s ib il i ty inthepas t30
years(Change t ter is tic s infogan
dhazew asc arriedoutinDec .20 1 3 .
a l .
[14
]
).Thevis ib i li ty trendcou ldbeattributedtotheThesampl ings itewasloc ateda t(
1 1 8 .7°
E,3 2 .2
°
N;22
increaseinsul furdioxideem i s sionoraeroso lconcen -
mabo vethesea leve l)
inNUIST(Nan
jingUn ive rsit
yof
tra tion
;however
,nocausa li tycou
ldbees tabl i shedsoInforma tionandSc ienc eT echno logy),whi chi snorthof
far .Many in-
s itumea surementshaveal readybeenc ar -theY ang
tzeRiverandsur roundedbyvari ouspol lution
r ie dout tos tudyhazeandfo gunderdi ffe rentrela tivesourc es,suchas
petrochem ic a lfac tori es,as tee l
p lant,a
hum id ity(
RH)
.Re sultssh owedthatlowvi sibi li tytherma l
powe rs tation,
ani trog enou sferti li ze rp
lan t,and
eventsunder lowRHcondi tionweremost l
yinducedh i
ghw ay
s(Lueta l .
[2 ,
]
).
byhe avyaerosol loading,
wh il ethoseunderh i
ghRH2 .2Ins trume nts
c ondi t ionwe reduetotheinf luenc eofaeroso lhygro-Theme asu rementscol le cteddur ingt
hefi eldexper-
sc opicgr
owthbecom ings
tron ge r
,whi chcouldlead toimentincludevi sib i li ty,boundary-
l ayerprofi lesand
lowv i s ib i l ityev ents evenunderm ode ra teaeroso lpo
l-CCNnumberconc entration
,amon gothe rs .Vi s ib i l ity
lu tants .Animportan tsou rceofaeroso lpart icl e si slo-
andreal-
t imeweatherw ere automat i cal lymea suredand
ca lemi ss ion (Ch anandYao
l
, 5]
).Someauthor sana -
recordedeve ry30sw ithaVPF-730AutomatedPre sent
l
yzedthehighe stleve lofatmosp
he ri ce nv i ronmentWe atherObse rv ingSy stem(B iral
,Bris tol
,UK ).The in?
po l lutantsinw inte rre su ltedfromveh ic leexhau stands trumentha sanoptical transm it ter,a forwardsca tterre
-
coa l/cokeem i ssions,andconcludedequal l y
impo rtan tc eiverandaback-
sc atterrec eive r,whichrecordfog
c ontri butionsof loc a lem i ss ionandregional transpor tdens i ty ,prec ip i ta t ionident ity,
rainra te,andsnowfal l
inN orthChina,unde rtheme teoro logi ca lcond i
tion so fra te.Thevi sua lrangeoftheinst rument isfrom 1 0 mto
lowtemp erature
, lowRH,we akradi ation
,andlow75km . There la t iveer rorofthe ins trumen ti s± 1 0% for
bou nda ry-
layerhe i gh t(Chenetal .
[1 6
1
;Che neta l .
[1 7
1
;v i s ibi l ityl e ssthan1 6km,and±20%forvi si bi l itybe
-
Da ie ta l .
[ , K J
).tween1 6and30km .
Ex is t ingresul tsabouttheeffectofhazeaeroso lsonDe tect ionofboundary layerw asdon eus i ng
foga reno tc ons i s tent.Som es tu d iesshow ed tha tthein -TPAWP-
3000m ic rowaverad iometer(Rad iome trics
,
c reaseofh azeaeroso l scouldstrengthenfogforma tionU SA
) ,wh ichdete cts tempera tureand liqu idwate r-vapor
anddevelopm ent(JiaandG uo
|
1 9]
) , andothersshowedprofi le sfromtheearth'
ssurfac eto10km.I thasfive
tha ttheradiat ioneffec t inducedbyhazeaerosolsc ouldoxygenchannel s andsev enwater
-vaporc hanne l,
le adtoreduct ionoffogoc cur renceinfrequency(Gau -TPAWP-
3000recordeddataeverym inu te .Br ightne ss
tame tal .
f
201
). Inrec en t
yea rs
,fogandhazeeventsoc -
temperaturerange is0-400K .Surfac etemperaturede-
curredfrequently intheYRDregionofChina;however
,tec tionandrelat iv ehum idit
ypre ci s ionsa re2%.
thetransi t ionofhazetofogi snotw e llunders tood .InTheab i li t
yofModel33 2 1Aerodynam i cPartic le
thi ss tudy ,weana l
yzedhaze -
to-fogtransform at i ondur-S izerSpec tromete r(APS
)tomakeaccu rate
inga long la st ing ,lowvi s ibi l ityepi sod einNan
jing
andm as s-we i ghteds i zedis tribut ionmeasurementwa seva lu
-
cha ra cter is tic sofboundary layerus ingi n-
s i tum ea sure -
a ted .Sampl ingfrequencywas 1min,an
dmeasurement
mentsofmac ro-
andmicro-
phys
ic sonhaze-
to-
fogday spa rti cl esc aleswe re0 . 3 7
-20|
xm .Asaresult,theAPS
inwinter20 1 3 .Th egoa lofthi ss tudyi stoanalyze3 32 1systemdetec tedpart icl e sthatwe re le ssthan0 .3
(
xm
h aze-to-
fo gtransformationmechani smi nordertopro-inaerodynam icdiame te rus ing
the lowes tsize bin .
v id em orescientifi cevidencefo ridentifi ca tionandpre
-Acont inuou s-
flowdu alCCNcounter (CCN-200
)
dictionofhazeandfogevents .The
pap er iso rgan
izedm anufac turedbyDrople tMe asureme tnTechno logie s
a sfo l low s .Se ction2de scribe s the in-
s i tufo gandhaze(DMT
,USA)wa suti li zed tomeasureCCNconcentra-
mea surements,introducing theobserva t ionper iod
,s i tet i onsa tdi fferentsupe rsaturationvalues(Robertsand
andda ta .Inse ction3 . 1,gene ra l informa tiononhazetoNenes[
221
;Lanc ee ta l .
[23
]
).F ivesupersa tu rat ionva lue s
fogevent s isdescribed .Se ction s3 .2to3 .4addre ss the( nom ina ll
y0 . 1
,0 .2
,0 .4
,0 .8
,and 1 .0%
)madeup
acycl e
m eteoro logica le lementsofwind
,tempera
tureandRHo fh al fanhour,ta
k ing10m info r0 . 1%and5m infor
inonehaze-to-
fogevent.Aeroso lsandc loudconcentra -
theo thersupersatura tionva lues .C loudroomto tala ir-
tionnumber(CCN
)concen trat ionduringhaze-
to-
fogf low ratewa s500cm3
min" 1
,ratioofbes tsh eathflow
transi tionareana l
yze dinse ction3 . 5 .
Summ aryandandsamp linga irfl ow ratewas1 0
:1
,sampling
frequency
conc lu sionaregiven i nsection4 .was1Hz
,andmeasurementparticl esca le sw ere0 . 75 -
S IZHANGShu- t
ing (张舒婷 )and N 1 USh eng
-
j i e(牛生 杰)69
1 0 .0 0
(
xm(L ie ta l .
[24
]
).pen
dedwa terdrople tsand/o ric ec rys tal s(
N a t iona lO -
Su rfacem ete oro logi ca lcond it ionsandsynopt
i ccean i ca ndA tmosphe ri cAdm in i s trat i on,1 995
).Haze
weatherdatawereobta in edfrom theCh inaM eteor olog- regim eoccursas atrans i t ionbe tw eenc l ear
-
sky
a nd fog
ic a lAdm in ist rat i on'
scompre h ens i veo bse rvat i onnet-reg imes
,andv is ib i l i tyi sh igh l
yvar iab l e inhazereg ime ,
work .Wate r-va
pord iv erge ncewa sobta ine dus ing
theHazeregimei sdefineda sv i s i b i l i t
ylowe r than5000m
Fina lAn al
ys isDa ta(FN L
)from th eNati ona lCen ter sunt i l
fogoccurs(E l ia seta l
.
[26
]
).Hazetrans i t ion
phasei s
forEnv ironm en ta lPred i ct i on(NCEP
)oftheUS .defin edbythesta rtofanaeroso lact ivat ionproc es
s .
Compu
ta t ionforhazeisdoneforv i s ib i l i tylow erthan
2000m,asdrop
letsappe ara tv i s ib i l itybetween1400
3 .
1Ge ne ral
info rmat ionon hazetofogtramform ationand2000m .Thev i s ib il i tyval ueso f40 0and8 8 0m
A tm osphe ri ccond i t i on sm aybec la s si fi edi n tocha rac ter izethetra ns i t ionphasebetweenfogandhaze
th reereg im esacc ord ingtov i s ib i l ity :cl ea rsky ,fogandregim es,wh i c his cons i sten tw i ththe500 - 10 00mv i s i
-
haze .Cl as s i fic a t ioni susua l lydonebasedonabs o lutebi l ity
i n te rva lcorrected .I nou rs tudy ,weuseR Ha nd
va lue sofv i sib il ityrange (Ta rd ifandRa smussen1
251
).v i s ib i li ty (
V is)
todefin efogandhaze ( Fi g . l
): it is fog if
C le ar-
shyregime isdefineda rb itrar i lyforvi s ib i l i tybet
-V i s< 1kmandRH> 90%;iti shaze , ifV is<5kmand
te rt han5000m, i ncontra sttohazyandfoggyc ond i
-RH<8 0%; iti sthetran s i ti onp
hase,i fVi s< lkmand
tionswhenv i s i b i l i tycanreachdram at ic al lylow er va l
-80%<RH<90%;an
di tiscl ea r-
skyreg imeifvi sibi li ty
ues .T he in ternat i ona ldefin it i onoffogi s anob servedval uei sbe tter tha n5000m .Thehaze -
to-
fogtra n s i t ion
horizon ta lv i s ib i l itybe low1kini n thep re senceofsu s-dur ingoursu rveycanberough l ydiv i dedin t
ofour
3 .
<a >
IA . !—— I
'
■
g Haze| |to fo
g II Fog| |Fog
2 01 3 / 1 2/4 | ||2 01 3 / 1 2/6| 1
2 01 3 /1 2 /8
t:; f !K :
i
ll i l JTii 1 -
〇 . 〇_
l
._yIt 1
RH(%
)
20 1 3/ 1 2/4I II20 1 */ 1 2 / 6I I 20 1 3/ 1 2/8
I
I
II I I
以I IIII
I
(C
)i
/i,iHMf LIHIHHHi 1! ■20 0
_ 0 .8 fr1
\\ g i i
-
-
ji 丨置 丨f■> 4^
吞 ij i : ij i i . i'HW i!_以
TO0 .4 - II IIII iij
flf I>
,MUS
至 。 .2 .U I !. I t 1M !J|'
'
0 .0 I^I . I .TA I.1
T(t :)
20
*
1 3/12/42 01 3 /1 2/620
1 3 /1 2 /8
T ime
Figu re1 .Tempo ra
lvaria
tionsof
(a
)v
is
ib i l ity , ( b)RHand (
c)
tempe
ratu re .B la ck l i
neisRH= 90% ,
an dgrayl i
n eisRH=80% .
Ta bl e1 .Start ing
time ,en di n
gtime
,d ur atio n,me an san ds tan dardd ev ia t
ion s( inparent hes is )ofkeyp
ropert
iesu nderdi fferen t
w eather co nd it
ion sin20
1 3 .
4Ac cumu lat ionCo arseparti c le
Ave rag eAv erage
Av e rag e .
,,
?」T i me_‘
part ic lenumb ern umber
Re gimeT ime pe r io d,Temp.KHV i s
du rat ion心 、,
n / 、 ,,、 concent rat ioncon cen tr at
i on
⑴ (%
)( km
)(cm
- -
)(cm
- '
)
S tart ing t imeEnd ing t ime
H aze20 1 3/ 1 2/32 3 : 4020 1 3 / 12 /4 1 0 :47l
l h5 . 673 .90 .7348 .2- 1 548 9 . 2534 .4-46 34 . 1
(2 . 0
)(4 . 9
)(0 .
1 )
H azetofog2 0 1 3/ 1 2 /42 3 :2 120 1 3 / 1 2 /51 0 : 26l l h6 . 684 . 50 . 527 4. 6
-
2 1528 . 945 9 . 4-
8 52 3 8 .7
(1
. 8 )(5
.
1
)(0 .2)
Fog
I2 0 1 3 / 1 2/52 3 :442 0 1 3/ 1 2 /68 : 2 09h5 . 8 339 1 . 90 . 722 5 . 7
-
1 1 1 86 .6 12 5 .9-
13 1 4 . 7
(0 . 5
)( 5 . 4)(
0 . 1)
Fog
II2 0 1 3/ 1 2/71 7 :
1 02 0 1 3/ 1 2 /99 : 3 233 h5 . 8 799 4.30 . 32 7 0 . 7-
1 52 45 9 .81 53 . 4-
94 1 42 .3
( 1. 6
)(6 .9 )(
0 . 2)
70J ou rnalof Trop ica lM e teo rologyVo l.2 2
stages(
Table1
): hazes tage(
2340LS丁(LST
=
UTC+8h)
_
广 . 二W3D ecem be rto1 047LST4Dec em ber
) ,haze -
to -
fog各知 、
s tage (232 1LST4Dec emberto 1 026LST5D ec ern -/
be r) ,fogstageI
(2344LST 5De cember to08 2 0LST6^283
L* .
f
De c ember) ,andfo gstageI I (
2 1 25LST6De cem bertoG%^
093 2LST9Dec embe r)
.
3 .2Impac tofsurfacewi
ndonhaze
-
to-
fogtramfor rna
-
?/0
,
6
、
‘
non
.
W indspeedandboundary-
l ayerstra tif
ic at io np ro-
?
卜’7
▽\)
、
v i dethewea ther b ackgroundforhazeorfogevents.A t
°
^r^r
surfac e,theweakpre ss uresy
s temc on tro l ledmos tar eas
ofcen tra lande as ternCh ina,andthedom inantflows\。
wer efromth esou thwe standwe s t,w i
thw i ndspee
dles s /
(
?T'
l〇
^^
\ ,/
’
tha n3ms
'
,wh i chcou l dre su lti nahaze- fogep isode ;
 ̄
k
(Yangeta l .
|
2 7]
)
.Ea r l
ystud ie soffo
rm at i ona ndevo lu t ion'
mechanism sofhazeevents inB ei
jing
foundthatthe卜 :
一
s\
p rima ryreasonsw eres tab l eant i
-
c yc lon icc i rcu l a ti onat^^y
* 79
i
t |.
? 4
^surfac e
, l ow er ing
thep lane ta rybounda ry-
l ayerhe igh t
(Denget al .
|
2 8]
).Wang e
tal .foundthattheco l da irbe-
\一"
longed to thehori zonta lthroughturn ingto longi tud in a l ^ ^S
,rTIt
s ty l e,
thegrou ndw ascon tro l ledbythe
pre- h igha n t icy
-
\
c lon eandthegroundfron tzone hadbeen
pre s sedtothe .一
J iangnanreg
io n |
l 41
.Zhangeta lshowe dtha ttheE as t.
.
,A ,
Y i
i
"
T
^
A s ianw i nte rm on soonwa swe ak inJ anua ry20 1 3 ,an’
^.
abnorma l lyh ighpre ssurecen te rocc urredat42 . 5°
N,
?
p\
1 20 . 0°
E,andtheco l da irof
p ostthroughw asd i ffi cu l t
to i nvadeeas te rnCh ina a sare su lt[29
]
.F ig .2i s theweath -,M
t
erpat ternove re as ternCh i nafrom0 800LST4Decern-為二
"
?
t3
ber to093 2LST9De cember20 1 3 .Athigha lt i tud e,a
1
7 \
-
T?
troughi nt
henorthmovede a stwa rdon3Decembe r,: A
andm ovedaw ayfi om J i angsuProv inc ea t
2000LST4j*
丄咖
,
Dec embe r.On5Dec em b er,theE as tAs i anma
jor二
troughmovedea stwa rd,wh il e them i d-
lat i tud ege opo-f *
^ }|||||^&Ajt^===s^-c= ::^
ten t i alhe i
gh tfie ldappe ar e
d tobezonal l
yor ie n ted . Un-j ̄
(bV .
t i l2 000LST8De cem be r,anupper
-
layer troug
hcom-’
'
^v
b i nedw iththem id-
lowe rl aye rco ldai rshe armoved'
v
^eas tw ard
,br ingingco lda irsou thw ardneart hesurfac e,\
.f
wh ic h im pac ted thewe ath er i nNa nj
i ng.A cco rd i ngto
-?
,\
1
thesu rfaceobserva t ion, t
henorthw es ter l
yp reva i l ed i n—
H?
Na nj
ingon3Decembe r,s inc ethec i tywasinfro n to fa
wea kh i gh-
pre ssuresys temtha twa sc en te redinNorth
C h i na .On4D ec embe r,t
hew ea kc o ld ai rmovedsou th-
^wa rda ndc aus ed
pres sure
grad i en ttodec re ase .Na nj
i ng1
wa sunder thecon tro lofhomoge neouspre s sure,a ndth e
windspe edw asre duced .Seve reco l da ir i ntrudedsou th-
t/"
.
I
wa rdsincethen i
gh tof 8De cembe r
,wh i chcau sed
pre s-
suregrad i enttoinc re ase,andw indspe
edin cr ea se dto'
^r
97
^
6-
8ms
_ l
.Thev i s ib i l i tyobv iou s lyim proveda t1 700
LST9Dec ember,and th el arge
-
sca l eh aze-
to- fo g
ePi S
w
e
T!;
e t〇 an end '
■
n ,fnW i ndd i rec t ionc anin
flue n cethetra n spor to f
po
l lu-4
—
—tr
一
ta n ts,w h
i l ew ind speedgre at
l
yinf luenc esatmosp
he r ic*
?iJ〇fc
'
d ispe rs ionc apab i l i ty .Lowwi ndspeed
inthehor izo nt al
d ire ct i on imp
l i es th attheatmosphe re isra ther stab le,an dF ig
u re2 .A ve ragesyn op ticweath e rdu r
ingt hehaze
-
to-
fo g
tha tthed i sper sionofl oca lem i ss ions i s l im i ted .A ir
-ma s sproces sof 4 -9D ecember20 1 3 . (
a)Su rfac ew i
ndfie ld; (
b)
transport canb ri ng inpo l lu tan ts o rc le ana ir from d is tan t,g
eopot en ti a lh e i
gh tfi e l d at8 50hPa
;(c
)geop otentia lh e i
ght
inf luenci ngloc alconc ent rat ionsof
pa rt i c l e s.fie lda t500h Pa .
S IZHANGS hu-
ting(张舒婷 )and N IUShen
g-
j ie(牛生杰 )7 1
F igure3shows thew indspeedwa s les sthan1mwec ou l dconc lud ethepo llu te da ir m as sesfrom we stern
sl
inthehazeevent,w h ichhel
ped toma in tai nthesta
-a rea scon tribu tedto thea cc umul at i onofpar t ic l esi n
b leboundarylaye rne art
hesurfac e .
Surfa ceroughnessNan
jing (
Fig .4)
.When thew indspe edsl ow eddown ,the
a l so inf luenc e sw indspe ed.C i t ie sw ithdense lyd i s
-hazebegan totran sform in tofog .Loca lem i ss iona c-
t r ibu tedta llbu i ld i ngshaveh i ghsurfa ceroughn es s,compan i edb
yregi onal transportfrom we stw as re spon
-
w h ichs low sd ownnear -surfacew in d .Loww indspeeds i ble fo rthepa rt ic l es inhaze-to-
fog trans i t ion .F ig .5 a
ind i ca tes tha td i spe rs ionhadb eenweakenedove rtheshowsthespa ti a ld i str ibu t io no fsu rfacew in dd i re ct ion
obs erva t ionreg ion . I nF ig .3,i nthenorthwes ttosou th-dur ingthehazeeve nt .Thes i tewascon tro l ledbyt h e
w es tbyw es t (
NW-WSW) thew in dsp eed(
W S)wasnorthea s terl
yw i nd ,wh ic ht ransp orted thepo l l u tant s
h i
ghb eforehazetra n sform edtofog,andtheconc en t ra
-fromtheno r th tothe s ite,w h i l ethesouthw es tpa rtof
t i onof ae roso landCCNshowedare l ati ve l
yh igh leve l.theobservat ions itewa sdomi na te dbyw i ndfromthe
A ccord ingtoHYSP LITbackt rajectori e sandfi reho tnorthwe st inthehazeevent .An inver sere lat ionshipbe
-
spo tsfo rthehaze -
fogpe ri odsdur ingtheobservat ion .tw eenconc en t rationandw indspeedsugge sts thep re-
Zha ngXiangz
h i,thedepu
tyd i re ctorofTe st i ng
ce n te rofdom ina nceofloca lsourc es,be c ausest rongw indsent
Depar tmento fEnv i ronmen talProtec tion,said
“
Thepo l lu tantsou tof thes tudyareawhe rea swe akw i nda l
-
conc en tra t ionsofpo tas s i umi onandb la ckc a rbon inthelowedpo l l uta ntstoac cumul ateove rt ime .Apa rtfrom
a i rwe rei nc reas ed .The setwocompos it ionsw er e0 . 5lo ca lemi ss ion
,reg i ona ltransp ortwa sreportedasan
t ime sh i
gher thann ormal .Th i s isca used b
ys trawb um-impor tan tcau seforpa rt icl econc en t rat ionintheatm o-
ing !Th esek i ndsofpar t ic le sm ain l ycam efromthespher icenv ironmen t(Pe tere tal .
[3 0
]
).Thewe aknorther ly
northofJiangsuprov i nce . Thewindsfrom the se d ire c-w ind l edto th eac cum u l at io nof aeroso l sa ndt he i r
pre-
t i on sb rought inpo l lu tan t sfrom strawcom bu s ti on;so
,cur sor saround thes ite (X ueta l .
[3 l
]
;Gaoe tal .
[32
]
).
0 . 00 043 . 758 7 . 501 31 . 31 75 . 02 1 8 . 82 62 . 53 06 . 33 50 .0
2^
#W i nd d i re ct i on
'
* I
'
(0
旦 .??J!
卜A4Aj^ tlii \ \U
20 1 3/ 1 2 /42 01 3 /1 2 /52 01 3 /1 2/62 0 1 3/ 1 2/ 720 1 3/ 1 2/ 82 0 1 3 /1 2 /9
T im e
F igure3.T emp o ra lv a r ia t io nso f w in dspeed andw in dd i rec t ion .
Fogformationre qu i resafavorab lewe at
hercond i
-
po rtorea c hNanj
ing .Ac cum u l at ionofwate rvaporin
t ion,sayasa tu ra tedwa ter
- vaporenv i ronm en t .Duri ngthe con ve rgen ce zoneh el pedfogfonnat i on i n th isare a ,
thehaz e-
to -
fog trans i t i on,su rfac ew indspe edwa sl ow
,W i ndspe ed in thefoge ventwasgrea te rthantha t
t hesamea sin th ehazeeven t,w h ichi sc onduc ive toa c- inhazeandhaze
-
to -fog tran sit ion .When fogwa s ind e?
c um u la tio no f
pa rt icu latem at ter sandt he ir i nte ract ionve l opmentandmatures tage s
,m ic rophys ic a lproce sse s
wi thwatervapor .Lowsurfac e-windspeeda lsoprovid-suc hasconde nsa t i ona ndevapora ti ondeve lopedwe l
l ,
edthec ond it i onforthe t ra nsfo rmat ion .Fo rw inddi re c-Whenthea irb ecamesa tura ted ,sma l lpe rtu rbat i on s
t ion ,F i g . 5bshowsthesurfacew inda l lcamefromthecou ldcauseo therphysi c al
quan t i t ie s(e .g .
,wa te rvapor,
southa ndconvergeda t the s i te,wh ic htran sportedwam itu rbu lenc e
,ortem pe ra tu re)tom akecorre spond ingad
-
andhum idai rtothes i te .The rew asaconve rgen ce l i nejus tmen tstoach i evean ewequ i l ib ri ums tate .Inth i s
near1 1 8°
E .Toth ewes toftheconve rgenc el ine,theba l ance ds ta te
,tu rbu lencecou lddeve lop ;so,var ia b il i ty
near -su rfacew i ndwasdom i na tedbyt heso u thwe s te rl y ;o fw i ndsp eedwou l dbela rger thanin thehazeeven t ,
totheea s ttotheconvergence
l ine,thenea r
-
sur fac eF i
gu re5 cshowsthew indf ie ldi nthefi rstfog
w i ndwa sthesou theas ter ly .T hesouth e as te r lyandeven t .Th i sfogl as tedn i neho urs .Tothenor thof the
sou thwes te rlyar e themos ttypi ca lc arrie rsforwate rva-s i te,thene ar -surfa cew indw asthenorthea ste rl y ;to the
7 2 Jo urn a lof Tro
pica l M e teo rologyV ol
. 22
C l uste rmea ns-
Stan da rd
33backwardt rajecto r ies
GDASMeteo ro log ical Data
?SHGE. '咖135
1
慧.
.
mmam,:
〇-3 000
< ‘'
、?2500
co
)2 000
① —- -———
^****^ ——1 500
a;1 000 「■^
▼^ 1 000
^ ̄
500
244872
F igure4.B ack trajec tor
ytoNa n
jing
72 ha ndfi rehotspot sonYR Ddu r
i
ng 1
-
1 5D ecemb e r20 1 3,
t he in t e rva lbe tw eentwop
oi
n ts
i s1 2h ,andt he starp
oin t i sNan
j i
ng
.
southofthes ite,
thew indwa sdom i na tedbythenorth-temp eratu rew as inthefogeve nt .Lowtem pe ra tureis
wes te rly .Low -
pre ssu rer eara i rflowincreasedc onve r-
genera l lyfavora b leformo is turecondensat i on,bec au s e
gence
,sowa terv apo rconden seda ndforme dfo g .The i tw i l lmakemorepa rt ic l eshygro scop icfora ct i va t ion
secondfogeventl asted60hour s,but no tcon tinuous l
y.andg
rowth .Thehaze -
to-fogt ransi ti onhappen edbas i
-
I twa sdom ina te dbythesouthe rl yw ind(F ig . 5d
).Ne arca l l y inth e i nvers i onl aye r.Thehe igh tof the tem pe ra
-
theob servations ite,therewastheconve rgenc ezone,
turei nvers i onwa sabo ut 400m .Whentherewa satem-
andthesou thea ste rl
ywindbroughtwarma ndhum i dp
era tu reinvers ioninhaze,the inver s io nin ten s i tywas
a ir,w h ichp rov idedmo i sture forthefog
top
er s is t .weakandthetem perature-
d ifferencewa s4X.knr1
o r
3 .3Impact of
temperatureonhaze -to
-
fogtra jisfo rinal ionl es s .Inthehazeeven tthetemperatu rewash ig herth an
T he rewa san inver s ionlaye rne arthesurfa cebe-thatd ur ingthetr ans i t ionan d thefogd aysatsurface,
foreth efo rmat i onoffog(N i uetal .
[3 3
]
) ,andthefogtherewa sl es swa te rvapo r
,aeroso lc onden sat ionwas
form ed inthe inve rs i onl ayer.After t
he form at i onof theweak,re
l eas el aten theat w assma l l ,
fog , theinve r si on laye rgrad ua l lymovedtoth etopo
fInthehaze -
to -
fogtrans i t i on
,the in ten s i tyo fthein
-
thefog . Inthedeve lopm en tstageo f thefog , tempe ra-ver s ionwa ss trong er
,andtemperatu re-d i fferenc ewa s
turedecrea sedatth em o is tad iaba t ic l aps erate .A tem-abou t6X.knr1
,approach ingtheinve rs io nlayer
i ntens ity
peratureinversioni sas tablestratificationandwi l lac
- inthefogeve n t .Du ri ngtheha ze- to
-fogtra n s i t i on , th e
c umu l atemo i s ture ande nergy i nthe inver s ionl ayer ;so
,th ic knes softhei nver s ion layerinc rea sed
,thebounda ry
tempe rature inver s ionprov idesaco nd it i onforch ang ing la
yerwa ss tab leandthewa te rva
poraccum u la tedat
s i zea nd chem ica lreact ionofpar
ti c les .n i gh t .
Fi
gure6s how s theprofi
le sof temperaturedur ingFogdeve l ope dinth ein ver s ionlayer
.The intens i ty
theha ze-to -
fog t ra nsforma t ion .Theh ighes tsurfac etem-ofi nvers i onwa sal sothemax im um inthefogeven t,
pe ratu reapp ear edd ur i ngthehazeeven t
,fo l l ow edbythoug hthetem pera tureinver si ond isappe aredsomet ime s
th ati nthehaze-
to - fogtrans it i on
,andth e lowes t surface inthefog even t.T h issugges
tsthatfogeven
tco u ldoc-
S IZHANGSh u-
ting(张舒婷)
an dN IUS heng-
j i e (牛 生杰 )73
37N-
|
—^
—一  ̄ 37N
p
 ̄
r—
r—
;
—
湖■
(迁)'
? ,、 ,
.
,、 、 、 v 、
/36N.
(b
\,一
广
一
7V7/
.
35N 、 ,」 .
、、 G.
v 、 、 、 、35N 、 .
34N*
34N-\\
^33N
-
. ,J\33N*J
"
^32N
'
? '
132N' '+ ■
■
31 N'
;. 1 3 1 N
Z\
::: ,.
^: ::
) /^2 7
H 2 E1 HE11 6E1 1 8E1 20£ 1 22E1 24EJ2 6E 1 28E
2 ?
n 2 E 1 1 4E1 1 6E1 1 8E1 20£ 1 22 E 1 24E_
1 26E 1 28E
3 7N t—
^
>
 ̄
:
 ̄
;
3 7NT i
3 6N.(C
^/
’?? ?
-
Wh\、36N
-d
j^ y\>
yV\V
r
r麵2 7
f
1 1 2E 11 4E 1 1 6E1 1 8E1 20E 1 22 E 1 24E1 26E1 28E
2 ? ,
1 1 2E1 1 4E1 1 6 E 1 1 8E 1 20E1 22 E
 ̄
T24E_
1 26E 1 28Eit
*
Fi gure5
.Vap orf l
uxd ive r
g ence(g/ (h
Pa ?
cm2 ?
s) )and
win dfie ld(
ni/s)on the
ground :(a
)0 0 00LST4Decemb e r20 1 3 ,(b ) 0 00 0
LST5Decembe r20 1 3, (
c) 00 00LST6Decembe r20 1 3
,an d(d) 0
000LST8De cemb er20 1 3 .Th e star i sth e ob se rvat io nsit e .
1-4Vx
<\'
—
n.N.\.—
*^
haze-
fog
wW f〇g
?
r ̄
1 .0■ /
'
■★
暑丨 : \\〕\
I :\U-
0 .5 -\1l
.
丨 丨 j■
0 .0_>
1
..
051 01 5
Tem pe rature(
°
C )
Fi
gu re 6.T emp
e raturepro fi
lesdu r
ing
th ehaze-
t o-
fog
tran s fo rmat
io np roces s.
c urinuns tab l e temperaturestra tific at i on .Thetw ofogTemper atureatthe inve rs i onlayerto
pw ass i
gnif
ic an t l
y
e ventsw eres l igh t lyd i fferen t . Inthefirstfogeven t,higherinthefoge vent t
han inthehazeevent;th iswas
s i nc e th erewa s thenorthe rl
ywind
,ani so the rma ll ayerduetothefactthatthefogi nthedeve lopmen ts tagere
?
began toappea rbe tw ee n100a nd200m
,a ndthenfogl easedla tenthea t
,inve rsera d ia t ionh ind eredlongwa ve
e xtendedtothegroundatth is lo cat ion .I nt hesecondrad ia t ivecoo l i ngnea rthesurface,a ndwa rmadvec t ion
fogeven t,wa te r
-
vap or t ransportfromthe sou thwa sonewa sa l soan importan tr ea sonfortheinver s ionat the
oftheimp or tantfac tor sfortran s i t ionfromh a zetofog .fogtop .
74Journ a l of Tro
picalMe teo rol ogyV o
l. 22
3 .4Impac
t of
RH o nhaze-
to-
fog transfo rmat ione rfractionofhazeev entswa scausedby
hygroscop ic
Ambi en tRHc an in fluen cehazeorfogformat ion,growthofa eroso l s .Thereduction in
pr imaryae roso le
-
developm en tanddi ss ipat i onbyaffecting
hygroscop
icm i s sionfu rtherampl if
i edthi seffect,an
dRHa lsohad
grow thofa tm osphe ri c ae roso ls .Underthesamep art i c l eobv i ousandimportan te ffectonthesc a le
,s i zeand
concentrat i on,theh ighe rt heRHi s
,the lowe r thev is i
-numberofa i rpo l l u tants .
bil i ty
be com es .Dur ing
t hehazeevent,
thema infeatures3 .5Haz eae ro so lcharacter is t ic sandac t iva tionratiodur-
wer eaccumu lationofaerosol s,
lowRHnear th esurfac e ing thehaz c -to
-
fogtransformation
andloww indspe ed .M ixtureandtrans it i onofpart i c l e sTab l e1showsth em in im umvalue sofac cumu la
-
andwa te rvaporusua l l
yhapp
enunderh igherhumidityt i onpani c l enumberconcentrat ionw eresma l le rtha n
thanhazeevent .Whenth eai rwassaturated,hazec oarse -
pa rt ic lenumbe rconcentration innon-
fogdays,
aerosolscouldb eac tiva tedtoformCCN,andth e andv i c ever sa .Them a x imumva luesofaccumu la t ion
ae roso lp art ic le s th atw erecon t inuous lyac cumu l atedpa rt i c l enumberconcentr at ionwe real llarge rtha n
cou l dmixandcoex is tw i thfogdrop le t s,thereb
ypro-coar se-
pa rt ic l enumberconc entra t ion,exc ep tdur ingthe
mo t inganexp
los ivedeve l opmentoffogevent . t rans i tionfromhazetofog .Thecoagu lationofhaze
F igure6show sthewater-
vapo rd i ve rgenc ein theaeroso lshappenedats izebe low0 .5
(
jl iti(Husa randHo l
-
groundlayer .Dur ingthehazeevent,thes itewa sina low a
y
[
M,
);
inpart i cu l a r,thereduct
i onofae roso l
part i c l es
regionof wa te r
-
vapo rdive rge nce(ne ga t i vecente r
),sug
- le ssthan0 .2|
xmdu ringthe trans it i onfromha /etofog
ge s t ingtha tmoi s tureconve rgedi nNanj
ingarea .Part i
-wasc ausedpr imar i l y
byc oagu l at io n (Ja cque l i n e
M l
) . I n
cl esbeganhygroscop i cgrowth
;bu tduetoh i
ghconc en - thehazc-to - fog
trans i t ionduringwh ic ha irwassa tura t
-
trat i onofhyg roscop i cpart i c le sandweakwa te r-
vapored ,somea e ro so lsi nac cumulat i onmodecou ldbeacti-
dive rgenc e
,part i c le sc ouldnotgrowin tofogdrop l e ts .vatedasCCNandconve rtedtofogdrop
letsthrough
Howeve r, th i scou ldserveas
preparat ion
periodoffog,condensa t iongr
ow th.Tab le2show sthat tempor a lva ri
-
naine ly ,con tinu edmo i s tureconvergencean
dwater-va-at io nsofaero so lnumb erco nce n trat
i on,ac cumu l at ion
por transportcouldturnha ze intofog .Lackofm o is tur e
,num bercon cen tra t ion,coarse -
par t ic l enumberconc en -
hazewou ldrema inas haze;wi thcoldai rcom ingdown, tra tion
,a ndCCNco ncent ra tion .Nc cn(CCNnumbe r
hazewou ldd i ss i
pa te .conc en trat
i on)va luedependeds trongl
yonwe athersys
-
Dur ingth eha ze- to-fogtran s i
tion
,al thou ghthe retern sduringt
hem ea suremen tpe rio d .H i
ghNc cnva lues
wasnoo bvi ousmo is tu reconve rgencene artheobserva-wereobse rveddur ingpe riod sofheavyae roso lpo llu?
t ionsi te,thedom inan tw indd irect i onsou thof thes i tet ion .Nc cnwa sfo undtobea sh i
ghas3 8 1 98 .4 cm
3
at
wou l dbringwarmandhum ida irfromthesouth,in
-0 .99%supe r sa turati on .Norma l l
y ,Nc cnwa sabou t 5929 . 1
cr ea s inga irhum id ity .Hygroscop icgrowthcont i nued,and9967 . 9cm
3
atsupe rsa turat iono f0 . 1 98%and
andthehaze cou l dtransfo rmintofog .Ano therpos s ib le0 . 397%
, re spe ct i ve ly ,a ndm orethan30000 . 0cm
'
-
at
re asonwa s thata i rpo l lut ionhadb ecomemorecomplexsurp ersa turat i onabove0 . 5% .Unde rdi ffe ren twea ther s ,
ove r theyea rs,andseconda ryaeroso lhygro scop icwasCCNconcen trat ion swe red ifferen t .Onthehaz e-to -fog
stro nge randmorei nc li nedtomoi stureabsorpt i onanddays,theCCNconcen trat i onwas theh i ghe st
,fo l lowed
growth lead i ngtoreducedv is ib i li ty .Th i smean sah igh
-bythaton thefog
days .
Tab le2.S ta t i st icso f CCNN umberCo ncen trat io n .TheN ccn (
cm3
)a
t fi vesupersaturat ion sarepre sented .Them i
nimum ,max
i
?
mum,m eanva l ueand thecorresp
on di ng
standardd ev ia tio na re presented .The l astl i
neis then umbero f samp
l es .
SS0 . 1 98%0 .3 9 7%0 . 5 96%0 . 79%0 . 99%
M in 1 . 6 1 5 3 . 846 9 2 . 351 73 . 5530 4 . 1
M ax1177 0.42554 63379 7 . 43 65 33 . 33 81 98 . 4
M ean592 9. 1996 7 . 91 138 7 . 6 1 21 87 . 61 22 62 . 8
S td195 8 . 9395 3 . 1470 3 . 251 04 .451 33 . 4
N43 15025 035 014 1 5
Inanattempttoanal
yzea ct i va tionofae roso lstole s s than1 5
(
jumw eretoosm a l ltoa ct ivateunder the
CCNandtheconve rs ionofCCNtofogdrop
l e ts,
thera - threesurper sa turat i onva lues
,wh i lep ar t icl e sof3 5
j
xm
tiosofact i va tionbased on the obse rvednumberc onc en -had thea ct ivat ionra t ioof 0 . 9a ta llthreesupersatura-
tra t ionofaeroso lsandCCN(N cn
(aeroso lnumbercon-t ionva lues .Mos t
pani c les of25
j
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Anunusualhaze-to- fogtransi t ionoc curredduringdeve lopedofhaze and fog .
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