A111111!1 q/'( :tnriofu,~r '..!!I 199-l
(" illll'rnational Glariologiral
Snrit"t~
Climate since AD 1510 on Dyer Plateau, Antarctic
Peninsula: evidence for recent climate change
L. G. T Hm1Pso:-.;.
IJ. rrd l'ofur R1·smrd1 <:r11/rr. Thi· Ohio S/11/r C11 il'1·ni!r . Cofu111h11.1 . OH ./3210. f".S.. I.
D . A. P F.EL,
Briti1h .l 11/11rc1i.- S11n•1:r . .\"alum( F.11ri11111111rul Rl'.11'11rd1 C:u1111rif. C:a111hri1~!!I' (;JJJ OJ;;T. F.11.ulo11d
E.
~1Jos u·:Y -TH0~1Pso:-.; ,
l~nrf 1'11(111 Rr.11·ard1 <.mll'I. T/11· Ohio St11/1• C11in•r.•i!1 . (.'11f11111h111.
OH .J32J(). C.S.A.
R. ~fl"L\"A:'\EY ,
IJ1 ili1h . 111/urrtfr S1111·~1· . . \ (1/111af T:11rir11111111·11/ Rrm11"d1 C.111111rif. ( .'a111firirfgr C:IJ.1 OET . F.11.!!ln11d
J.
l~rrrf
DAI , P. N. LI !'!, t-.1. E. DA\"IS.
1'11far R1 11wrh C:mln. Thr Ohio Stair l "11il'1'rri!r. C11f11111b111. OH 4.'1210. l ".S. A.
(:,•0/1/~nin
C. F. R .\nto ·D
P111,!!rn111. C11il'rrsi!1• q/ 11"11shi11.i:11111. Sm/1(1·. tr.I 9fll95. C.S.. I.
ABSTRACT. A -180 \"l'ar record uf thl' oxyg-t• n-iMJIUl'l' ra tios, du't n.1111t·11t,
r hemiral 'Pl'l"il'' and lll't arr umulatinn li·om ire r <H"t'' drillt:d i11 1989-90 on Dyer
Platt':tll i11 tlw A11tarrtiC" Pc·ninsu la is pn·,rntrd . The rontinuou' anal~'l'' uf,mall 1s11ha111111al J ~amp lt:' n·n·al Wt'll-pn''t'rYed a nnual n 1riatio11s in both sulliite content and
111
6 0. thus allowing an l'Xrrllen t tinw-sralr to be established.
Thi~ histor~ ren·a ls a rerent pru1101111n:d warmini;: in which the last two decadr'
han· bt'<'n among tlw "armc't in the last lin· rcn turirs. Funhrrmort', unlikt· in East
Antarrtira. on O)t'r Pla tra11 rnndi ti un~ appear to han• been fai rly normal fmm ,\ D
1500 tu 1850 wirh roolrr rnnd itiuns from 1850 10 l!.130 a nd a wanning trrncl
dominating- 'inn· I !J30. Rc·cnnstrur trd a nnual la~ er thirkncs~('s suggest an inrn·ast• in
net an·unntlation bl'ginning t·arly in tht' IYth re111 uq and con tinuing tu the pre,enl.
111
Thi' i11tuitin· rnnnicl bl'tWl'('ll increasing ni-l an·u1111ilatiun and dcpkti-d h 0 (l'Olllt'r
rlimate l in thl· I 9th n :ntury appears widl'~prt'ad in the pcnimula region and
r hallengc·s our under~ta ndi n g ufthc: physical relationsh ips among moisturt' ~uu 1-cr,, air
tt·mpt·ratures and snow arrumulatinn. Tht· romplex mt>teorulngiral regime in the:
Anrarrtic Prnimula rt'gion rnmplira tcs meaningful in terpretation of proxy imlic:ators
and IT,ult' in a 'trong imprint oflnral high- fn·quc·n c~ prnn·sst'> upon tht' largt'r-sr ak
rlimal<' pirtutT.
0
INTRODUCTION
,\ rn-opt•ra rin· .c;lariulo.c;ir al climatologica l in·-cotT drilling prug-ram "·a, co ndurtt'd on D) er Pl ateau
70 -10' 16" S: 6-l 52'30" \\": 2002 m a.~ . I. : nwan annual
tc:mprrature: - 2 1 C 1 ht' tWt't'n 1988 and 1992. Tht'
program draw' upon the t'Xpt'rt ist· uf each e;roup to
C''tabli,h a -180 ~ t':tl' palcoe111"ironmental his tory or tlw
..\n tarrtir Pt'nimula rn{ion Fig-. I l. In 1988- 89, a
gt'11phy,iral program " a' initia ted and two icP rort''
\\l"rt'' drillt'd 10 a dt'plh ur 108111 al a lot·ation ti km \\e~111r
the rli,ide. In 1989-90. t\\n COl'l'S were rermerrcl 1 m
apart 1111 tht' rn•., t nr D ~t· r Pla tt'au (C"urC' I - 233 .8111 a nd
rnn- 2 - 2'.l!i .2111 1 ancl t\\o 31Jm core:' 11t·rr rlrillt'cl -lkm
-l:ZO
I
east uf the dilidi:. In 1989 -90, the geoph)'ir al measurement~ were expanded to r nc-ompas' tht: new c111..lora1iom a Wl'll as potential li.11urr drill 'i tt'' (papt·r in
prrparation by C. Raymond a nd 01hers 1. lre-c-ort: qualit ~
Yarird from exl'cllen t t long. contin1111u' p it'l't'~ in tlw
upper 112 m 10 \Try poor (li-arturt'd ;ind \\afi:n·d 1 hd1m
190111. T he hiswr~ prc·sentt'd hert' is frum the top 112111 111
run· I 1:\0 1761 - 1990 ) a nd the lower part 1112- 190111 111
cure 2 1.-\ 0 l.i0-l- l 760 i. Tht' rn111plenw111ary 'ectinn' 111
both rorrs are being ana lyzt'd at tlw British ..\nt.trr ti1
Surw~ 1BAS t a' part of" thi, joint prujcct.
Tlw. ntarrtir Peni1i-ttl:1 arn1 is a rli111a1irall) rompl1 ·'
a nd 'en,iti\ r re~ion '' hich extt'nd' nort h" ard anm~ 1h•
t·i rum-JJL>lar trough i Sl'hwt'rdtle~n. 198.J. ). This j, . 1
Tliu111p.1011 n11d 11/ltrr.1: (;/i111alr d1t111gt 011 LJ_rrr Plalrt111 . •·l11/11rrli<' P1•11i11111/n
o'
Antarctic Peninsula Region
+1a•s
South Atlantic Ocean
Weddel/See
+
Amund..n·Scotl
SouthPol1
Fi.f!.. I . Tltr /orntin11 of tltt' l~ rrr Pin/mu drill ,i/r in tltr
• l111arrtir Pl'lli11s11/n rr.ci1111 iJ i/1111/rall'd a/o11g u·illt nlllfr
,!!m~rn/1ltil'frnl11rts 111r11/io11rd i11 !hr In/.
major arra for sea-in: proclurtion and thus meteorolngiral
ronditioni. arr ~trnngly alfl'ctrd by variat ions in sen-in:
rover m·er thr acljal'rnt oceans and the \\'edclr ll Sea. This
pwjert i~ part ur a continuing clfort to construct a glohal
rlimatl' ' Yntht•,is for ilw last 1000 years with spt•t·ial
emphasi, upon the charac:tn and temporal synchruneity
of the "prel>UITit'd'' muM rC'rrnt Nt>oglarial en:nt ofttn
railed the '' Little Irr A~e" !LI A )· . Tclentifying and
unclt-ri.ta ncling the linkagr' lwtwrt·n dimatit· ,·ariations in
lu\\'t:I' latitudes and thost· in the polar rt:l{ions should
1·nhanre our a bilit y to iclt'ntify a nd undn,tand tlw
mcrlrnnis1m rc·,p11nsibll' li1r gl 11hall~ ~ign ili canl rlimate
lluct u at iun~. Thr Antarnic Pl·ninsu la i~ a kq· 'itr li1r
clima tic and envirr111mr 111al recuni.trul'!ions from icr cores
and pnw idl's a cri tical link bt'twcen rt·nircb li·om tht·
intrrior 111' Antarr tica and thosl' r·mngin~ from South
.-\nwrica . First. a 1·u111pr1·ht·n, i\T rlimaw hi, 1nry li1r tlw
prni11,11 la rl'gion mu'l he n·constr11necl - a li1rn1irlabh1ask ~i\l· 11 lht· llll' l l't1r11l11~ic al a nd 11rt"a11ic r11n 1pll'xit ~ uf
t lw . 1 n-a.
in thr labnratorics at tlw Byrd Polar R csl'a rr h C:t'n ter
<BPRC) and the Brit i,h Antnrn ic· Survey.
Sampks wrrc cut r11n tinuuusly alo11g the enti re lt>ngth
of the rn n: and each sample was a nalyzed !Or mirropartide
rn nrentration I :\lPC J and ,izr dii.tributio n, nxygeni,otopic ra tim (61110 ). liquid ronduni,·ity 1 LC l and
ronrentratiom of st>lrr ti-d inorga 11ic aniom. ~l PC. liiuO.
LC and anions were mea,ured a t BPRC. All mc>a,url'111
ments exrept 6 0 were condurted unclcr Cbss 100 Clran
R oom conditions. Tht' t·nncTntration and size di,1ributio11
of particles with diam eter~ 2:: 0.63 / t lTI ml I 'amplt' \l'l'rl'
mra~urrcl u'ing a model TA- I I Coulter Counter
!T hompson, 1977 ). Cunduni,·ity of liquid sampks wal>
measun:cl with a Bl'ckman moclrl RC:-1 6C rnndueti,·icy
bridge. The rnnrr ntratiom of thr major :rnion' or r hloride
1Cl ), ,ulfa ti- tS0 12 ) a nd nitrate 1:'110:1 \1·t·rl· ckterminl'd
\\'ith a Diont·x modl'l 2010i chromatograph eq ui pprd \lith
an A 4A anion ~eparator rolumn .
Total /3 radioacti,·ity is routinl'I) LN'd to iclt:ntif)·
kno\\'11 time ~ tratigraphi« horizons aswr iatcd "i1h pa'l
almusphcric thermonuclear trsts (Crozaz, 1969). Snmples
wi th nrnssrs between 250 and 350 g were r ut from th e
upper 30 m of the rore. These wt·re acidilircl, melted and
pumped through ion-t'xcha ngt· filters, after whirh total f3
raclioac ti\'ity was measurcd by a Tenneler LB I000 Series
low-bark rround fJ rountin~ systC'm. \\'hen identified .
the~e radioactive horizons allow \'erification o r si-a~unall y
\'arying parameters and pro,·ick rnnfirma rir111 or the
dating of layers youngn th a n 195.J. 1PicriotlO and
\Vilgain . 1963 ). Figun· 3 illus trnte~ thr Ji radioat·ti\'ity
prnlilt• along with so/ and 11 111 0 for ear h >:1111pk in thC'
11ppn +om or core I whirh t'llC'fllllpass the las t j3 yl'ars.
1'\ntr that till' lir'l major in«n':IM' in 11 racli11al· t i ,·i1~ lll'«Ur'
in 1963 ti+. c11inride111 \\'ith 1%.J. iclrntilil·d ll\ rount ing
· ·
· ...,, o .-, a11 d u• 111 0 .
·
Ill
;1111111 a I ,· a na1111n~
1
The high annual aec u11111latiun ratc orU.·Hm l\,atrr
1·q ui,·ak11 t1 allo\\·ed each :1111111al layl'r to hr r ut into an
a\l'r:l):'l' of 15 ''11n plrs m·a r lhl· top a nd , i).. ,,1111plr' al
1111 m . Thi~ ' a111pli11g ,r(H'nH· 1nu ltrd in +l :Hi 'a mpl•·>
Borehole Temp. (°C)
-19
0
-20
-21
,.
ICE-CORE ANALYSES
c:
\
40
'tr;11igT.1ph~
and cll'11,i1y FiJ.{. '2 \\l' rt' 111l'a,11rl'cl
im11wd ia1«1~ in thl' li1·ld . Thl· li11n·l111k 11·111pt"ra 1url·
pr11lill' wa, cl r tn111i11l'cl usinl! l\\'O tlwrmi, tm·, " ·i1h
r;i lihra tion rr'i,tanc"' at 0. ( j . - 30 and 50 C:.
Bon·h11k lt'm pnatun·'· llll'asut'l'd I year ;rr1a rrtrit·,·al
or thr l'll l't', rangt• frum a mi11imu111 nl' 21.:16
al j3 m
111 a maximum ur I!1.8!1 Cat 2:lO 111 Fi~. '2 . All in· rnre~
\\'t'l'l' returnt·d frozl·n li1r phy'il·al and rlll'mi ra l an.tly't''
\ 'i,ua l
-E
80
-
~
.r:.
Q.
Cl)
·22 300 500
..,..
"
700
900
\~~
120
0
160
..
200
Tit« tnm I.in Ir 11r .\ g t· l.1.-\ i' l'1111 trmTr,ial a' thr
l'\·rn 1 h:t> nut hr1·n clt·mon, tratcd 10 lw global. alth11ug-h
t' \ irl1·nr1· nl 1·1111li11g dUl'' 1·xi'1 a\\ a~ from llw \ 11rth
..\1l:i11ti1· "·lwn· thr LI.-\ i' a pro111i11rnt li:.11un· in
1 li111 :1 1r rn 11rcb. Tlw tnm i'
UM·i'ul .1, it ).!<' lll"r,dl ~
i11rlir:111·, .1 rnol 1.ll'1il•cl IWl\H'1'11 ~ . \I> l:iOO .111cl 1!100.
.dthnug-h 1imin){ :111d inrcn,i 1 ~ a rt' qu il l' 'a riabll'.
-3
Density (kg m )
.'
.·
240
Ft,t:, . :!. T/11• lm1/11 r11/11n· /1n!/il1 ;, 111 1111w 11111 ,/ i11 /ft,· /'il(J
!JO /~1 r1 /'/111.1111 li1111·lt11/1· 1111tl tf, 1111/i, ., ,, .,.,, "''"'"''ti 111
100111
"'""!!. """I .
+:? I
Th11111/11 ,.11 1111d 11//11n : (.'/i11111/1
.111111~1 1111 /~11·1
Plu!r1111 .• l11/111rli1 Pl'lli1t.111/a
~ {dph kg . , 1
s"o c·1" 1
0
200
400 ·30 ·25 · 20
0 ......_......__.__.___,
so.2·
0
(µeq. r 1)
c1· (µeq. r 11
No3· (µeq. r 11
Par1icles per ml
4000 8000
2
3 0 2 4 6 8 10 0 0.5 1.0 1.5 2.0 0
r-::::::,;;~::::::=
5
10
.,.
.. 15
ii
.§.
e
0
(.)
20
.!:
.c
c.
Cl>
c 25
30
35
40
Fi.::. 3. T/11· 11•11fii11w11.,. 111111(1·1·rr 1!/ b111 0 . SO/. CJ . . \ "O·; . anti i1w1/11blr /111rlirulaln ( di11111rlrn ?_().fi311111 J arr
1
i/111.1/111/rdfril !hr 11/J/11·r ./0111 ( 193i- !JO ) q{ 1 urt I un /J. rc 1 P/alrau. Tlir ncdlml(l' /11nrnwl 1r11so111tl rariali1111 • in ~ "0
a11d su ,~. (•Jl!fi1111r1/ l~r !hr !%JG./ t3 liuri~Ull . /m11 ·idr II /ir(risr li1111 -.l"((l/1 '" .J/I 15(}().
1:ad1 for ~ IPC: a11rl c'> 111 0 a11rl '.!850 'ampl1·' for a11 iu11,.
Tl11">t' anaJy,c·, rt'' t•a l ll"l'll-prt·"·1Trcl . a11nua l 'arialiu11' i11
huth so, ~ a11cl h111 0 \\ hirh makl' tla1i11g the rnrl'
,1rai!{hllur"arcl. Figu n· :3 iJlu, 1ra11:' 1ha1 so, ~ sh'' " '
111
1hc: bt•llc:r 'c:<1>unaJi1 y 1ha11 0 0 a11d l)H· lack of \\ t•JI.
clc:lint'cl >t·a,ona lity in tlw c·o11cen1rnlions of C J . 0 .1
and clu' I ro111c·111. lcl1:111iliratio11 of known ,·ukanic: t'\"t'lll~
1di,Clh<t•rl Jar •.., lc:nd~ runher , upport lO tlll' timc·-,ca lr . A
prrr iM· 1i1111·-,calc- i' tbt· lir~t \lc·p in rll'\·rloping hil("hrt·,ulu1i1111 hbtnrit·, of a1n11i-ph..-ric d1hl co1111·n1. h1110 ,
almc>-pht"ri<" rlw mi'lr~ a11rl ne t annu al an·unwl;i ti nn.
RESULTS.
111
liltn and re1·c:a l 1ha1 in 15e1H·r:d 1hr :weragt' 6 0 rt>r11n),
d11 t"a )Jlllrl' ll1U l"il of lht )argt'·SC<l )t' f1•atlll"l'S u(° 1111"
tt·mp1·1-.11urr hiswr~ a l H a lk~ Ba) ( ~l'l' R~ ,·alut' g-i\l·n
in Tahlt· I 1. .Jo111:-. and url u:r-; noll'd lhl' m·cc"ity 10 a n a l ~z1
add i1io11al con·s frum thr peninsula and lO includ t' rl u·
analyses of both 61110 and OD in future ,cudic·"
Tlw Dyn Plateau rrrord presented hr n· prm·icb
information fr<Jm an additional sitr "hic h is fi ' furtlH·•
'oul h anrl 360111 hi!(her than.J a mr~ Ross (, )and, Jt)(J(J .111rl
870 m higher than Dnlll'm an Island or the Gnml'z ,j11·.
n·spt"rtiH·I)', and 6.5- :3.5' C: rolder (a nnu a l :l\·rraKe th.111
a11~ othtr penin-;11la drill sitr (P1·el. 1992) ...\1thi'1in11· 1 I l
lllt'a,un·mrms li;we 1101 hern made but an· pla11111·d in 1l w
nc:ar lt1turt' .
or
.\> ll"ilh all~ in· l'lll"t.' . thl'' l' Jii,writ , rdln ·1 a ("l)ITil>inal ion
Juc-.11. rl'1~i t1 11a) .md Jar~t"l"-,l'.rl<" prtJll'' >t°.\. Of 1110,1 illll'rt''t
.ire· 1h1· rq{io11al a11cl lari.:c·r->ralt- rnmpo111:1ll' 11 hir h iclt-a ll ~
-;houlrl bt• inl l'gTa ll'cl '"i1h othl'r ..\n tarnir Pl'11in,ula
hi,turir' lU a'l'l'rtai11 a hruach:r pinure tJf thl' climate
hiswr~ or 1h1: region. Cnmpari11!{ records from an a rra~ or
>i tc·~ al~o hkhliglrn spatial dilkrence> whirh ma~ n·lkn
mnre luraliz1·cl prncr,,e,...\ recent paper b~ J om"' and
nthf'I"\ I 199:3 1 di,c u,secJ thr rnmp(exity nf the lllClt'Ol"lllUgica) r..-gime in the pc·ni1Mila rrt:iun. thr largt· ,pat ial
\ ariahiJit y or r JimaU." paramrll:"I"• ~uc h <l' temp..-ralUrP and
1ht> nwdiorrt rt"lation,hip httwet"n h111 0 and te111p..-ra tun·
111
1R :::::0..1. The a111111al an·ragf'' of 6 0 fro111 '"" D~ cT
Pla 11:au C"IJrt'o;. tht' 1989 90 OSL" rnrl' drill.-cl a1 tht platrau
nr, 1 and th.- 191:18- 89 B.-\ S rnre clrilll'd Ci km 11 e,t. a rr
illus1r.c1rcl in Fig1irr 1-. l nrlud..-cl arr lht' an1111al tAugusl 111
1h..- fi11lo 11 ing .Jul ~ 1 an·ragr 1rmpt·ra 1urr> frum H a lk ~ Ba ~.
lo 1t·a11·cl on lht· rna'l lo 1hr t'asl an oss 1he \\'i::clddl Sc·a.
Thl'>t' 1hnT Jii,lurit" an· ' 111001h..-cl '' i1 h a ~ ~ t'ar Gau"ian
Tab/( I . C111 jfiri111/1 11{ d~1m11i11alio11 ( R1 ) /111 11 li1m11
1
1r/al1u111hif1t1111u11.1.:.1111111111/(r 1111'111.t:rrl f/" 0 from Iii u IJ.1 c1
P/11lr1111 ia ru rr.• 1111d 111n111 a111111nl lr111prra/11rn 11/ Ha/1,:1
Har. All a1111111d 111·rragr• ;,•m .imunllird il'ilh ll 5_re111
GauHill11 filler
Hnllr1
f'aramt/er
T C:
1.onu
~ 1 ~0 - BAS
O.tiB8
t!:.!9.9''/,, I
0. 178
198.U"'i,
l.OUO
0..!1 3
(!-J9.9" ;.
1.on11
Tlio111pso11 nnd othrn : Climntt r/11111ge on D)•tr Pia/Mu, Antarctic Pmi11rnln
Halley~.
-27+-~~.--~-,.~~-.-~~.--~--,.~~-..-~~~~--i--21
1970
1960
1950
1980
1990
Year (AD)
Fig. 4. Tilt 1958-89 nnnual avtragts of 6180 from lwo Dyer Pia/tau cores, tht 1989-90 OSU corr nnd the 1988-89 BAS
core, art compared with the annual average temperatures ( August lo the following July) from Hnllt)' Bay . All three records
were smoothed with n 5year Gaussian filler. The osr..; core was drilled al the plateau crest and the BAS core was drilled
6 km lo the west.
In 1985 a 302 m core was drilled at Siple Station
(75°55'S, 84° 15' W , 1054ma.s.l. ) at the base of the
Anta rctic Peninsula (Fig. 1). As on Dyer Plateau the
excellent preservation of seasonal changes in 6180 and
SO/ - (Mosley-Thomson and others, 1991 ) provided a
550 year history of environmental conditions (MosleyThompson and others, 1990). To expand our view of the
climate and environment of the peninsula area, the D yer
Plateau records are presented with comparable ones from
Siple Station. This comparison highlight~ mo re regiona lly
extensive trends dominated by larJ!:er-scale processes and
also bolates dilfert'nn:s.
Oxygen-isotopic analyses
records n:ficct in va rying degree~ ( I ) the air
tempera1ure a1 which condrnsa tion occu rs, (2 ) a tmo-
6 1HO
Oxygen Isotopic Ratio (°loo)
spheric processes occurring between the water-vapor
source (oceans) and the deposition si te, (3) local
conditions which dominate during firnification, a nd
(4) the surface elevation and latitude of the depositio nal
site (see Dansgaard a nd others, 1973; Bradley, 1985, for
review). The correlation of atmospheric temperatures
with 6180 and its spatial representativeness are still under
discussion ; nevertheless, 61110 is u ed widely as a climate
proxy, particularly for temperature Uouzel a nd others,
1983; Thompson a nd others, 1986, 1989); Johnsen and
others, 1992; Peel, 1992). As shown in fig ure 4, the recent
61110 history appears to rellect the major ti-mperaturc
tri-nds in th e Weddell Sea sector (Table IJ.
The decadal averages of 6 111 0 for Dyer Plateau and
Siple Station (fi J!:. 5) reveal the ah;ence of a prolonged
cool period from 1450 to 1850, ronsis1e111 \\ ith t:a rlicr
61HO hi>torics from Jamt·~ R os> l'la 11d Ari, tarai 11 :rnd
Adjusted Annual Layer Thickness (m)
Decadal Average
Oyer Plaleau
Siple Statton
-30 ·29
0.3
Oyer Plateau
0.4 0.5
Siple Statton
0.8 0.4 0.5
0.6
·24 ·31
·28
·25
2000 .....-.........,,....-......___.
2000+-~'---r~-~
1950
1950
1900
1900
1850
1850
~ 1800
1800
:. 1750
1750
1700
1700
11150
1650
1800
1600
1550
1550
~
1500
Ave.• -25.e "too
Ave.• ·29.e "loo
1500
Av•.• O.« m
Ave.• 0.51 m
Fig. 5. Drrndal nu raxn rlj. 6 1HO and rero111/rurtnl l1!vu thicknt>W> 011 J)_ia Plntt'llu 1m illus/raled 1t'ith ro11r111"1"r11t
hi.1 /orie; f rom Siple Station /urn ltd 11/ thr b11> f of the .-l11/t1r<'lir Pminwln.
Th11111/11111111111'11/h1·1.-: l .'/i11111/r 1'11111~·· 1111 /~ r1•1 P/1111'11/1. A1ll1111tir l'ruiw11/11
11tlwr,. l!Jl:ll .md 011lll'n1<111 [, land I Pl·1·1. 1992 1. Thi,
1·li111a tl' ,n·n.trin j, dilliTl'nt frl1111 tha1 found in li 1':0
n•r11rd, from E:N ...\ntarrrica 11r fi·um , itt·, r1·nwn·cl from
till' \\'1·dckll S1".1 'l'\ t11r :\l1 i-lt·~ -Tho1111N111. 199'.! 11 lwrr
r1111li-r than norm.ii ro nditi11n' w1·n· motT prl·1·alrnt prior
111
t11 lltlO. Tlw l>)t"I' Plal t":tll 1: 0 hi, 111ry '11ggr't' a 1nark<·cl
n111lin!( l1l'll\'l'l'n l!H·ll a11d lfl j (), ali1·r which 1·111,lt•r 1ha11
111Jr111al wncli1io11' pn·1·a ilt-d li1r a 1t"llllll'). T hi, .-i-n111r yl1111!{ r 11ul pl'riocl i' nt•t 1·1 ich-111 at Sipil· Station a t tlw h:t , l'
or till' pl·nin,ula . 011 thl' 11tl1l·r hand. th<' Sipk Station
111
1'1 0 ·rl·c111"CI. lik1· that from D)l'I' Plat1«1t1. rl'n·ab nu
prolong I'd rnol J>lTil•d priur tu l 8j!) Fi~. j . Thl' lar k or a
111ark rcl root pl'riocl nn D) 1·r Pla1ca u in thl' middk or thl'
pl'ni1h1da and at Siph- S1ation. all)ng 11ith tho~1· li·om
, 1·tt·1:d 1"11l'l'-t' ll·1·a tion . l11111•r-lati tuclc- p1·nin~ula ' itr,
l'n·I. I !19'.! . prm·icJ,.s an 1· 111t>r~ing 1·i1·11· or tlw di man·
11r 11 11· Ja,t h : dl~111ill 1 · n11in111 in tlw pl·nin~ula n ·f{ion 11 hirh
i' q ui tl· clilli.·n ·111 fi·11m 1h.i1 in Lht ...\111arnira. Tlw O)i' r
Pla11·a u !'1 111 0 ri·l'onl 1Fig . 5 1 inclicat1•, a n i,11t11pi1
11anning hl'gi11ni11g- in l!J30 .t11d L'Xtt·nt.ling 111 thl' pn''t' lll
tl1L' warming al Siplc· S1ation j, n11m· 1110d1·,t 1. On 0) l'I'
Pla11·a11 tlw la, t t1111 dl'1· ack~ ha1·l' hl'l'n ammu{ tlw
" i,11t11picall) .. warmt'~t thrt'l' ckr adt•, 1tht' 11thl·r hl·ing
1113 1- +IJ , in 1lw la>t fil'I' r1·nturi1·~. lihtrum1·11rnl n:c11rds
indicatr that tlw warming , incr IY:JO appl'a1-. tn hr
r<'ginnall) 'ii.: nilican1 throughou1 th t.> pL·ni11'lda . For
n.ampli-. from 19+'.l to 1992 trmpnaturt'' at farada)
ha 11• 11 a rnwd nt'at'I) 2..'i C ljont";; and 11thr1,, 199'.l l.
Furthl'r e1·idl'llt'1' 111' this 11 arming is rrlle\'tt'd in thr ra,picl
di,illll'gratiun 11r ilw \\'mdi ... In· S lwtr fi·um ~ 20011 km- in
I lJb(j tu :::: 700 k111~ in I 98!1 1Ouakt' a11d \ 'a 11ghan . I!l!l 11.
Spli-1htt1t'' ' l'r ! I!J92 1 rq>ttrtl'cl the n Te nt n·trl'at ol'
:\urtl11·a't Glacier 011 S11rni11i.;t1111 bla11d ahout 65 mik'
i llfl km I nort h or tlw \\'urdit: kl' Slwlt: Thl·,c· 11IN'l'1·a1ion,. a lon)t 11ith 6 111 0 l prnxy l rn:ord ~, inclii.:atc a n ·c1·nt
and r11nti11ui11~ 11 annin~ trrnd i11 tlw p1·11in,ula rq~ion.
Annual layer thicknesses
\
.-\nmtal ht) t'l' thirkn'"' " " prrn idr a hi.111r) 11r thf' llt'I ma''
at 1 u11111lati111; i11 a g i11·n ) ear hut do 11111 n· llt·l't
prn·ipi1ati1.'11 amou11h dirrl'll ) . l ' nli1rtu11att"ly. ht)t'r'
thi11 a' 1ht') art' huri1·cl h) '"h"·quent an·umtdati1111 a11cl
a' tht') an· ' trl·trhed 11 hen thl· irl' llu11·, out11«trd li-11111 the
lTl''t ur the platl·att. Om· 11hjl·11i1 t' or the c111nplrmt" 111 a ry
!.\l'oph y,iea l ,lllcl~ i, 111 pr1J1·iclc- infunnatiu11 alJt1lit tltt• ll1J11
1·harat·11·ri. 1ir' or thl' in· arnund th e bun:hl)lt' tu .1djt1, 1
nwa,un·d a1111ual layer thi r km·,,l., lur ' ueh thin11i11g. 011L·
i111p11rtanr a"umption i' that thl· ' urfo r t: 1 crtical 1·t:lucit y
i, 1·q ual to thl· , hort-trrm :H'ClllllUlation t'<l!l' nt' 1.1 6 m a 1
nwan d1·mit) = +OU kg m 1, ol11ainrd from ' ta kr 1111·;"urt"mt'nt' for th r pt'riod l!-JH9- 92 ..-\nother a;;sumption i~
that th ... 1t'l11r i1 y ancl dl'n, it y pnifile~ h;11 t.' remainn l
t'11t1, 1;1111 111 l'I' tim e. ...\ df'tailt·d cli,nt ~'i<m of th<' linal
a nnual la)i-r rt"n 11htruni1111 i, in prrpara tion h) C.
Ra) nw nd a nd 1Hllt'r,; h111,r1·t' r. thr- trl'11d in thi-,t'
l't'l'lll1'tl'll l'lrd thiekm•,st'' I Fi o. .i 1 i' 11111 r xpr1"11·d tn
1'11at1!1,t'. al th11ugh lhl' linal thil'kllr""' 111 ;11· 1 al') ' liglttl).
Fi \;urt· 3 illlhtr.tt•·' llw d1·radal a1 r- ra!,:"' tJt' tilt'
n·1·1111-trun1·d a n11u.1l l:t) 1·r tl1irk11t'"''' .4 11 I ti1r l.111h till'
0) 1·r Pht1t'a11 a11d Si pit· Station rnrt',.
11 l1111g-1t· rn1
-mo yl'ar , 1n·11CI i, ,., iclc-nt a1 t'ithrr ,itt'. altl11111gh w11-ra l
, h11rt-t<Tlll 11t11hi-ckrad al 1 111·11tb a pp1·;11 111 b l:'. ·') 11chr114'.l l
Tah/1• 2. C.111·/.licit-1111 !1/i/1'11 r111i1111ti1111 , fl~ J. a11 .~i1·m /i1r
II li111111 rd11li1111.1hi/1 lir/;1·11 II 1111'/t< l/lfd iu•-(u/1' 111111/1/11011/.1
in 11 1nrr /i·11111 .~i/J/, ,\ /11/i1111 11111/ 11111•.fm111 l~ r.i /'/11/1'1111.
.-11111111/ira
l ' fllr/1111•/(1
Panin datl'•
1'111 timla11•1
,~1~ 0
f:1tt'.i.1 .\0 / '
...i ..
o.+7j
' ~l!) . !l
h1'0
0. 01
:\S
Exn·" ~o ,~
().j8'.)
99.(1
0.'.l-1-7
.-\"
!l!l.l l
• R1 indiC'atn tlw rrartinn
.,r
( Jilt' 1ariahli- 1ha1 j,
1·xplainl'd b) th r- othn aml tlw lt·n ·l of 'ii:11ilir a1w1· 111
lht' rdatiu11,hip i' gin·n in pan·nthl" '''· .-\n R~ vi' 1.11
indicatt" a pl'1frn rdatiunship. ·s implit:' 1ha1 R~ 11a11ot ~i~nifit·ant at a11 y accl'ptablc len·l.
nrnt• 1R1 =0.:.1+7. >il:(nifir ant al thr 99"!,, t... w l: Ta hli- :.!
Fmm .\n 1.100 to :::: 1700. A 11 int' n-as1·d , tig-lttl) :ti h11tl1
., i tt·~ afi1·r whi..t1 A 11 clt"nra,t'cl In :1 minimum at l 7j0, Tl ii·
minimum j, 11111rt' pru1111u11,·ed at D)lT Pla11 -.1u tha11 .11
Sipl1· St.1ti1111. SinC1· 1750, .4 11 ha. inr rt<t>l.'d ~raduall) .11
buth ,j11·' althuu~h 11101'l' >tr11n!(I) at D) t' t' Plall'all tl1;111 .11
Siple Station. Thi. lll't arntmulatiltn incr«ast• ,inn· 17.j ll j,
in !{l'lll'rnl agrn·ment \1ith th u>i: on .J ame, Ru" .11111
Dullt·man I sland~ s•'l' Pl'l'l. IY92; .Jones and 01h1·1-.. I!l!l:i .
.\, norrd h~ .)0111•, and othl't'> t 1993 ). in thi, n·!{i1 111. ti ...
6 111 0 an<l .411 hi,tnri1·, a rt· not r orrelatl'd a, 1·:0. p1·1·1,-d
a»u1t1ini;: pn·ripit:ition inrn·ast'' wi1h tl'mp1·ralt1r<'. T li·
h 111 0 and .-\ 11 rer11rd, l'rom broth l>)·,.r Pl:11r-au a nd Si pl•
Stat ion rurtht'r M1ppun 1hi~ innm.i,tt'nry; 'Pl'( ilie.tll) . .Ill
i>11t11pirally rnul pt•riud (:::: 1800- 1930 i, a"11ri.111·cl 11 iil1
i1wr... a, in!{ nr-t arr umulation . Thi' pat1rrn . .1pp:1n·111 h
ll'idt', pn·atl in the penin,ula . i11dka1r' a mon· 1·11111pln
rr-lati1111, hip a1111111!( 111oi, tun· 'uul'l'n. a1n1u, pl11·ri1 11·111·
pn:11un· and hu111idit) . a11d 1wt , 11011 ar1·um ul:1ti1111 tl1.11
i~ l·•rn1111u11ly a" umt·d .. \ , till' pl'ni 11,u la i, a nwtl·11n •l• 1-irall) r ompl1· x rL·~ion . it p1i>1'' a l(rral r halll'llg• · 1111
acn1ra t1· in ttrpn·tatiun 111' in· con · prox) dat.1 .
Dust content and excess sulfate
The .JHO yl'ar hi, t11rit'' of' du ~ t clepo,irion ar O~-.·r Pl:i t1 "'
and Siplr Sta1io11 ( Fi~ . 6) :ne quitt' , imila r R1 = ll.1- ·,
,ignilir ant at tht' 99.9%, ln·rl : Tahir 2 11 ith 1"C1n'i'tr 111:
lu11 rn11ri:n1rati1111' fr11111 .\l> 1500 ut11il ll11· 111irl-l ll1h 1·1·11t111'
Tht' l't' art t1111 pr11111i1w111 rlu,t ll-aturr, at IJ<•th ,ill'< I
thr- ~r:trlual innr.1"' i11 d u' t 1·1111!1." lll ,i nc1· !Will .111d '
tl1t pr11111int'11t dti-t n ·1·11t frnm 1598 111 ICiOO. Th.- i111-r1··' ''
i11 du,t ,i11rr 1850 i, pnpl t'xing i11 1 i... ,, 111' tlw 10111·un 1·111
dt'l-r1·a"· i11 tt'111pcr:i1un· !IJ 111 () 1 :ind i11crr:1v· in 11 °·1
a1T11 111tda 1i1J11. Thi'><' 1111, t·n a ti 11n, r:1i•r 1hr q 111·,ti 1•11
1,llt'lhl'I' thl· i111Tt'a>t·cl <lu'I rcllrr 1': 1l l a 111• •1 1· tl 11,1 1
Thum/111111nnrl11/hrn: Climalr tlin11,g1 011 Dl'rr Platrnu ..·111/11/"t'fif Pr11i11J1il11
Dust Content
(Diameter ~ 0.63 µm per ml)
Oecadal Average
Excess Sulfate
(ueq.
r•i
Oecadal Average
Dy81 Plateau
2000
0
Dyer Plateau
t500 3000 0
Siple Station
Siple Station
4000 0.5
1.5
2000
2.5
1950
t900
1850
1800
0
~1750
j
1700
1650
1600
1550
1500
Fi,!!,. 6. D(rad11 I m·m1grJ id' /11/nl d111/ <'1111/m/ ( dillm(/rn
?_0.6.11w1111I 1 ) 1111d r\t'f.U 1111/11/1• ( EXS) 1111 /Jyr
Pl11/M11 Ill'<' i/1111/l'llll'd 1..ilh fOllfllrrml lti.11urirJ from Siple
St11tin11 lorn/I'd 11/ the basr 1!/ tltr • l11/r11 rlir Pmi11.111l11.
atmmplwre. n·~ult inµ- !'mm 1a I m<ll'l' l'ili:rtin· 1·111rai1111wn1
pr111·e,st''· 1h 1 inl'n·awcl ''llll'f'<' arl'a a, iC'e n·tn·at in the
)ll'lliw.ula n:g-ion 1·xp1»l'cl mun· b1·drrll'k nr 11·1 a 'l'mip1·n11a11t"11l di,plarenll'lll ur primary rirnilati1m lc:aturt·,
which l'l'SUltrd in thC' 'outhwarcl i1d\'f'C'lio11 ufc) u,l. a nd /or
::! 1 1·111rai11mr n1 111' clu,1 in th1· mnrt· p11ru11' nppl'r lirn
layer' durinl-( clrilli11g and tran>ptl!'Jatio11 . Tilt' l:u ·k ,,r a
'i111ilar i11nr·a"· in th1· 1un1T11lra1iu11' ol th1· tl 1ro·r major
.11111111' Cl . SO/ .111cl :\0:1 I '"~!:(l''I' 1ha1 rill' dti-t
i11tTl':tM' i, pr11h.tl1l) not :t>M11·ia11·cl 1.i th 10111.1 n1inali1111
hut clot•, rel kn a n-.tl i111 Tt·.1,1· i11 a 1n1u,plll'ri.- cl"' l i111·"·
.-\, p.1ni.-11lat1'' an· cl1·p1i-i11·d hy liuth 111·1 :incl cir~
pr111 1'" t''- it i> dilli111h 111 >1:·para11· thrir 1·1111 1rili111 i111"
11 i1ho u1 :i 1·11111i11u11th. nwlii-1 l'ar. in ,j111 ' 111111 :incl air
':i111pli11g pr111.(ra111 . l'n·1·i1111' '1ucli1·, in Ea,1 .\ lllan 1i«a
:O.l11, l1·1·-Th11111p,11n. 1~19:! .111d S11ur h .\ 11ll'ri1·a Tho111p' "11 .111cl u1 h1·r,. I !IBIJ n ·p•Jrt 1·d i11.-n ·awd pa ninilail'
rl"P'"i1i11n d11ri11l-( 1•111),· r )J1·riucb.
Thl' >l'l'11nd pno111i11l·n1 d11>1 li:atun· i' :111 .1hrupt a11cl
l.1r).(t' clu'r incrl'a>i· li-11111 ) j!)!:I 10 1600. 111 l.i~IY. cl11>l
11111t1·nr in1Tt' awcl Ii) t1l'arly :1 1:1r1t1r 11r 10 ar bilrh Dyl'r
Pla11·au and Sipk Statiun. Fiµ-un· Ii ahu illu-irat1'' li1r
liul11 n 1n·, rht' t'Xl'l'" ,u )fall' EXS 1 11r nun-~1·:1 - ,a It ,1111;, t1·
'.'\")S _ :1clj11't1·cl u'i11g Cl 101 "'ri111a11· rill' "'a-,,tlr n>1np11111·n1 Dai and urh1•r,_ 199 1 . EXS i, 'uh,ra111ial1)
l'l1·1arl'rl li-11111 l j 99 111 )1jOI. ~ugg-1·,tinl-( rha1 llw ,1111:1 11·
.1rri1 1·cl at l11 11h , i11•, I ) <':tr al'Jl'I' tlH' p.1nin ilatl''· Tiii'
111 i~i11 11r thi, l'\'1'111 i' unkn1111 II. . \ ltl10111~h llll' l tiUO
l'l'U)lli1111 uf H u.1ynap111i11a in , 1111tlwrn P1·ru i, prn111im·n1
in 1h" Q.u1·li-1.1) .1 ,..., 11rcb Thump>11n .1 ml 111111·1" . Ill~jtj
and ha, lit·1·11 n11r1·cl in EXS in (;rl'l·11l.111cl 1J h1·,1· autl111r>
i1 i' unlikd ) 1h.11 th1·,1· pani11ila11·, • ll'i~in . 1r"rl lr11111
H uay11aputina . Giw11 the large r11m·1·ntratio11>, tl11:ir
11rigi11 i> prohahl~ lura L I r i\ pos,ihlt' that H uaynaputina
t'CJ11trihu tr cl tn tht' de1at1·cl EXS i11 1601 liut it cannot be
till' ~o urc-1· liir EXS ll'hil'h lirst arril'l·cl in ) j!.J8.
H11 ay11apurina has y1· t to hr iclt"ntilil'cl cnnclthil't:ly in
,\ ntarrtiC' icr-r 11re rl'rurcls. _-\,n·naining \\'httht'r tl1t' dust
i, of 1·olca11il' oril{in i, a logirnl next 'trp "' 11 di ;i,
inspl'C'ling 11ther .\ ntarrtir rt'rurcl> for thio, po!l·111ia l
"nwrker horiLon ''. Thr EXS hi>tt1ril's li·om Over Plamlll
and Siple:- . tat ion , Ri Q_j83. , igniliranr at . rhc 99.Y'Y,,
ltn•I: Table 2 a lo ng- 11·itl1 EXS hi,tori1·, rrom Grn·nlancl
11 ill rnntrihutr to thr clt"1't'l11pml'nl of a global 1·ulcanir
hi>tor~ liir the la~r liw 1·1·nll1ri1·s.
Tht' EXS hi,tnrirs liJI' Sipk Sration ancl Dyer Platrau
Fil{. G, rn·l'al a numho.: r 111' kn1111·n n 1ll';inir l'n·nt' a' ll't'll
a' ''11111· u11id1·ntilircl ... , 1·nc-. lckn rili ration uf knoll'n r1·e:-n b
prm·iclt'> timr-<.ca l.- nmlirmation . I 11 aclcliciun. th!' rrren1
harkv;ro1111cl n1111 t"11t rati1111 ur EX S may 111· l'umpan·cl ll'ith
that from thr pre-inclu,rrial era t11 cll'll"rminr wlw1htr
.- \n1arrtir snn11· i, )t't 1·onta111inatl'cl by :'llo rtht'l'11 Ht'mispht·n· inclu~trial arti1·i1ic·s. To make this.. rnmparbon.
) t•a1-.. of known 1·ulranism (Fig. 61 ll'l'l'l' n·mm·rd fl'tlm the
record prior to :11·t·ragin~. In thr Oytr Pla tl'au 1·on· du·
ra l i11 of t'XC'r!ls SO/ li·om I H.'i I tll 1990 to l ha l li·n111 1600
to 1850 i> 1.18/ 1.1 5 1/t.t'C) I. 11 '"~g't'> lin~ l'i rtually no
r hangr in tht' EXS MHll'IT ~i nn· 18.)U. A 'imilar ra lrnla tion
liw EXS at Siplt- S1:11i11n g-i11·, a ra tio ol' 1.:.12/ J.:l-t.
indicaring a , )ighc inrrra": in !::XS ,in e lfnO: howc-l'rr.
th is clitli-rc:nce i0.09 11t·q !. 11 i> l'l'l'Y nt"ar the a11alytil'al
prtr ision uf the anal y,t·s and m:1y lw lllt"ani11g-lt•>'.
=
CONCLUSIONS
Thi· 1·1111"rging pak·udi111a11· hi>l •ll'Y li·um D) c·r Pla11·au i,
prU1 icling' l'urt hl'r i11,ig-ht i11t11 lhl' rn:iunal hi,tory 111' 111l'
.\utan tiC' Pt'ni n>11la. \\' lll'n 1 il'111•d alrn1g with .1 n1111parahk hi,llll') f'n•m Sipl1· S1a1i1111. n·rt.1i11 n-g-irn1al 1liar:11·11·ri,1i r> htT111111· t·1·id1·111. Tli1·,t· int luch· n ·latil'l·I)
1111r111a l rn11clitiu1h · 1 ·. ~. 1111 I.L\ . li'tim LillO 111 II-DU wi1h
C11()lrr l'11ndi1ion' lh1111 IH.'iO 1" 1hc· 111icl-:?Oth n ·111ur) .
( '. ouil"r 11111cli1iun> 11nr ·"'"ri.11l'cl wi1 h .1 gr:1rlu:d i11n 1·:1,1·
in 1111· llu.\ lli' i1h,,l11hl1· clu,1 .111cl .111 i111Tl'a><· in 111·1
:ll'l' L1Jlllllatiu11. :\o maj11r inrn·aM' in t·'(1·1·" 'lilfa1" at'"'""''
i, 1; 111ncl 11 hid1 'liJ.\g'l''h 1111 a111l1r11p11!{1·11il' r111111 ih111i"11 1o 1
' """ i11 1hi' n ·g-i11n .
Thl' pr11111i111·11t warm in;! , inn· I!l.-1tl 1111 D ) 1·r 1'1 :111·.111 i'
n111'i'11·n1 11i1h 11th1·r ul1><'1'\·.11i111h i11 I),,. n ·!{i1111. p.1niu1larly 11w"· 11n tl11· 111·,1nn ' icl1· 11f 1hl' p1·ni11'td:1. Thi'
111
11-:1r111inJ.\ in 1111· la>I ll-w clf'1:td1·, i, 11111 1·1 idl'll l in h 0
hi,tori"' from 1111· Ea,1 .-\111 arr1i1· plat•'.lll . l'h1·"· l'l'~i11nal
dilli-rl'11t·t·, :tl'l' 111>1 u11lik1- tl111>t' 01111· 11·1111lcl lincl in 1111'
lll1' ll'Olr11l11gil'.tl hi>lfll'in or .J.\lt1hal1) dbpc·r,nl ' lalifllh ..-\
1·11111pari>11ll or rill' cln·aclal :11 l'l':ti.{l'' li1r illl' la't :i\1(1 y1·:11·,
fr11111 clilli:n·n1 in· t'<ll'I'' n·11·:1), 111arkt'cl cl illi:n ·111't''·
Fig-un· :! in l'h11111p,u11 and 11tl11·r, I ! llJ :~ 111111p:ll'l·,
lin· >Ill h hi't"ri1·,: C:1111p C:1·11tlll'). C1 n ·nl.111cl : l>unck ill·
1·:q >. China: Cltlt'kr.11·:1iu· 1·ap. 1'1'1'11: and Sipl1 · .111cl 'i11111h
p,,k Sraci1111' .. \ n1ar1 lira. 'I ""'" Iii"· in arldi1i1111 111 llll'
Dyl' 1 Pla11·:1u n-.·11rd pn·,1·n11·cl lll'r1· a11d :111,, Jl1c·1 n·r11rcl
1· 11w rl-(in~ l'r.1111 till' (;uli ) a in· 'ap i11 111·'tl'1 n C'ltin.1
T h..mp, •1n .111cl t•illl'r,_ )l)•l.l: a11cl unp1tl i)i,l11·cl rl.ll.1 .
r1 ·1 o·;tl 111.ll 1111· l'l'l 1·111 11 ar111 i1t!\ Ii." ll1·1·11 11111,l pl'<•_ _J
1.,-
T/111111p.1011 1111d 11/hrrJ: (./i11111/1 d11111g1 1111 D_1•r1 Pln/1'1111. A11/111 r/1t' Peui11111l11
no um·rrl at llw hi ~h elt',·atinn . non-polar ' itrs 1Dunde.
Gu liya and Qur k raya ire r ap' J and in tlw Ant.trrti1
Pt'nin,ula . l "p to 1980. no \\ a rming was e,·idt•n1 a t dw
South Pnlr. At Siplt' Station th r roolr r condition' in the
last tTtllury havr ht'rn n: plar t'd by a \»arming tn·nd in
th1· la,t two dt'rade' whirh is ri,ing j u' t ahm·r tlw longli:rm awragr . Thus. th1· rt-rt'nt .. gluhall~ a\ nagerl
wa rming'' is nut t•\·idt'nt at all latitude,. Tht'' t' in:-rnn·
hiswril'' an· particularly ,·aluabk "' tht'y pruddt' a
lon~er-ti:rm pt't'-pcnin· from which tht• , ignilirann· or
a ny rrcent r hangt·' ma y he 1·1aluatr d .
ACKNOWLEDGEMENTS
\\"e thank tht' per,onnel from the Byrd Pola r Research
Centr r and the Briti'h Antarctic Sun·ey who participa ted
in the field prog ram, and Bruce Koci of the Polar let'
Co ring Office !PICO 1 which is ~ upported under a
contrart from thi: L·.s. Natio nal Scienci: Fo undation.
We gratefully acknowledge the logistical support by thr
staff and BAS Air Unit at R othera Station. K . Dnddroe
typed the manuscript and J. '.'lagy prepared the li~ures .
This projt'ct wa' 'uppo n ed b) U .S . National Science
Foundation grants DPP-8716384 and AT~J -90084 - 7 to
The Ohio State L ni,·crsit) and U . . National Science
Foundation g rant DPP-8716243 tu thr Uni1·et'iitr or
Washington, and support to the Briti ·h Anta n:tir Survey
was provided h . the U .K . Na tural En vironment
Ri:search Council. We thank P. D. Jont'' fur hi' imightful
cumment~ and va luable ' uggi:,tion,. Thi, i~ cuntrihutiun
Number 872 or the B~ rd Polar Ri:scarrh Ccmcr.
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