AD-AC7 9 640 COLD REGIONS RESEARCH4 AN0 ENGINEERING LAB HANOVER NH G4/LAKE CHAHPLAIN ICE FORMATION AND ICE PREE DATES AND P.EDICTIONS--ETC(U)NOV 7R N E GATES , A GRO W

UNCLASSIFIED CRREL-79-26 NL

I flllfffll..llffmmKmmmmmmm

'P.

REPORT 79-26Lake Champlain ice formation and ice free dates

and predictions from meteorological indicators

-,set

Cover: Grand Isle Ferry Docking Slip, GordonLanding, Vermont, on Lake Champlain,February 1977. (Photograph by R. Bates.)

CRREL Report 79-26

Lake Champlain ice formation and ice free datesand predictions from meteorological indicators

Roy E. Bates and Mary-Lynn Brown

November 1979

Prepare~d forDIRECTORATE OF CIVIL WORKSOFFICE, CHIEF OF ENGINEERS13yUNITED STATES ARMYCORPS OF ENGINEERSCOLD REGIONS RESEARCH AND ENGINEERING LABORATORYHANOVER, NEW HAMPSHIRE, U.S.A.

Apprtove(I tr iub i rh',1,%P Fjtrbutfon tinlinjitm (I

UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE (When Data Entered)

READ INSTRUCTIONSREPORT DOCUMENTATION PAGE RE COMPLETIORMBEFORE COMPLETING FORM

1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER

CRREL Report 79-26

4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED

AKE HAMPLAIN J.EJORMATION AND CEFREE .ATESICTIONS FROM METEOROLOGICAL ATORS S. PERFORMING ORG. REPORT NUMBER

RD NFO EERLGCLINDICA R ~ ___________ __

7. AUTHOR(s) a. CONTRACT OR GRANT NUMBER(&)

\ oyE. Bates am* Mary-Lynn1 Brown ] ( .

!. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK

U.S. Army Cold Regions Research and Engineering Laboratory AREA & WORK UNIT NUMBERS

Hanover, New Hampshire 03755 CW IS 31361

It. CONTROLLING OFFICE NAME AND ADDRESS . FT OAT&Directorate of Civil Works Novom*9 79

Office, Chief of Engineers. . NUMBER OF PAGES

W a n ton, D C 023 14 2

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Approved for public release; distribution unlimited.

17. DISTRIBUTION STATEMENT (of the abetact entered In Block 20, If different from Report)

13. SUPPLEMENTARY NOTES

19. KEY WORDS (Continue on cevere aide It necesary and Identlfy by block number)

Climate LakesForecastingIceIce breakupIce formation --7c

2okM,'rRACr Ctaue a veverse ftl.* i .? d ideal f by block number)

A 19-year record of the annual closing and opening dates of operation of the Lake Champlain ferry at Grand Isle,Vermont, which are controlled by the lake's ice cover, was made available to CRREL. These navigation records ac-curately approximated the freeze-over and breakup dates for the ferry crossing area between Gordon Landing, Ver-mont, and Cumberland Head, New York. When compared statistically with water temperature and climatologicaldata for the same years at nearby Lake Champlain locations, the dates ajowed accurate predictions of ice formation.

From nearby air temperature records, cumulative freezing degree-day (Qt) curves were plotted for each year of recorand ice formation dates and standard deviations were predicted with considerable accuracy. Several methods ofpredicting ice formation on Lake Champlain were attempted. The most accurate approach used a combination of

DD FOr,1473 E0ITION OF NOV65 IS OmLETE U"l,,,

tJ TS Uncla,;,;fipd

- SECURITY CLASSIFICATION OF THIS PAGE (When Date Ente*cI

. .. . .

UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE(Whan Dote Seted)b20. Abstract (cont'd).

'Aater temperatures and freezing degree-days. The influence of wind speed on ice cover formation and prediction areedIso Iiscussed in the report.

ii Unclassified&CCURITY CLASSIFICATION OF THIS PAGE(V1,m, Date ffntot.E)

PRE FACET his report %%as prepared by Roy f Bates, Meteorologist, and Mairy-Lynn

Brown, S( ient Aid, ot the Snow and h. e tBran h, Researc h Division, U S Army(old Regions Reseatc h anrd f nigineering Laboratory

I he study Was ( On~dltte~l Under DA Program Ice I ngineering, Subprogram IceDecay. Work Unit CWIS 11 361, Jhermal Regirnes Disturbed by Mar)

The authors express appreciaition to Dr. George D Ashton and] Ric hard K.HaUgerI for their helpful suggest ions (onerning the Stutdy anid for tet hnitalreview of the Manuscript. I hey also express appret. w~tion to the Lake ChamplainI ransportat ion Company, Burlington, Vt ,espec ially to IJolhn (anm. for pirovidingret ords of the dates of openinug aind ( losing ot their ferry serv it e and dlat a onwater temperature

I he U S Army Atmospheric Sciences Laboratory (White Sands, New Mexit 0)meteorological teamn based at CR RE L furnished and installed the meteorologicalInstrunentation and tabulated the meteorologit al leld data tor the winters of1975-76 at Shelburne, Vt., aind 1976-77 and] 1977-78 at Grand Isle, Vt.

The contents of this report are not to be Used for advertising, publication orpromotional purposes. Citation of brand names does not (onSt itUte an official en-dlorsement or approval of the use of such comnmercial prodlucts.

CONTENTS

Page

Abstra( t iPreftm eii

Introduution 1Data tabulation and collection 1

Air temperatures 11-reezing degree-days 3Water temperatures 3

Closing and opening dates 3Results 3

Air temperature 3

Freezing degree-days 7

Water temperatures 7

Analysis: Attempted methods of predicting ice formation 8

Predicting air temperatures 8

Summer water temperatures 8Fall water temperatures and freezing degree-days 8

Wind speed influence on closing of the lake 12Water temperature vs surface air temperature analysis 12Prediction of ice-out dates 14

Conclusions 15

Literature cited 16Appendix A. Freezing degree-day curves with ice notations and water

temperature notations 17Appendix B. Summary 21

ILLUSTRATIONS

Figure1. Test site locations in Burlington, Vermont area. 2

2 Water temperatures at Lake Champlain. 63. Computer regression analysis plot, Burlington Airport Data 13

4. Average lake water temperatures vs air temperatures for Burlington,Vermont vs Oswego and Rochester, New York 14

5. Mean annual water and air temperatures, Burlington, Vermont,

1962-1 978 15

iv

TABLES

Table1. Air temperatures (OC), Burlington, Vermont 4

2. Monthly average water temperatures. Lake Champlain (OC) 5

3. Data tabulated from LCT Co. freeze-over and open dates 64. Days to closing of ferry at Grand Isle due to ice after occurrence of

4, 2, and 1 OC water temperatures 105. Predicted freezing degree-days and closing date of Ferry as com-

pared with actual, using water temperature o(currence of 4, 2, and10C 10

6. Predicted closing date of lake for two winters from a similar winterversus "normal" 11

7 Comparison of water temperatures and ice formaition at severalsites on Lake Champlain 11

8. Ranking order of accumulated freezing degree-days and ac-

cumulated wind vs closing of Lake Champlain at Grand Isle,Vermont 13

9. Slopes of air vs water temperature determined from Figure 4 15

V

LAKE CHAMPLAIN ICE FORMATION ANDICE FREE DATES AND PREDICTIONS FROMMETEOROLOGICAL INDICATORS

Roy E. Bates and Mary-Lynn Brown

INTRODUCTION DATA TABULATION AND COLLECTION

This report summarizes several climatological Air temperaturesvariables: freezing degree-days (accumulated Average monthly air temperatures were ex-below a base of OOC), air temperatures (1959-78), tracted from Local Climatological Data: Burling-

and water temperatures (1962-78) at or near Bur- ton, Vermont', for the years lanuary 1959 - Maylington, Vermont, which is situated on Lake 1978. Air temperature data for this period were

Champlain (Fig. 1). Annual opening and closing measured at the Burlington International Air-dates of the Lake Champlain Transportation port, 5 km inland. Although average monthlyCompany (LCT. Co.) Ferry, located at Grand Isle, minimum and maximum temperatures exhibit aVermont, were provided by the company.' These greater amplitude range at the airport than onopening and closing dates are controlled by ice the lake, the average monthly temperatures atcover formation and decay on the lake, CRREL both locations are similar'.established and operated a meteorological sta- A 17-year mean monthly temperature andtion at the Grand Isle site during the winters of standard deviations were computed for each1977 and 1978 and at Shelburne Point, Vermont, month, as well as a 17-year average annualalso on Lake Champlain, during the winters of temperature*. The3e calculations served three1975 and 1976. purposes. First, monthly temperature departures

The overall objective of this study was to from normal for each year were easier to identi-examine climatic variables, lengths of ice fy. Second, a 17-year monthly mean temperatureseasons, air and water temperatures, and freez- with corresponding ice data and watering degree-days. Specific objectives were: 1) to temperatures was compared with the 30-yeardetermine the relationships existing between air monthly normals for Burlington, Vermont, com-and water temperatures and ice formation and puted for the years 1941-1970, and presented inbreakup on Lake Champlain; 2) to determine if Climatography of the United States, No. 81, forany correlations between these variables might New England4 . Air temperature trend com-be useful tools in the prediction of ice formation parisons were also made with the record of

and breakup dates; and 3) to determine the ef-fects of wind speed on ice formation. Several ice *When comparing air and water temperatures 17 years of airformation hypotheses were tested from the temperature data were used When computing freezingavailable data and references with various degree-day curve, to compare freezing degree-days with lakedegrees of success, closings 19 years of air temperature data were used (App A)

L."

73*25 --

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ChamplainAirport

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Plattsburgh- Shelburne Test SitePoint

ShelburneBayj

Burlington 44258.5 8mdepth

0 20m contour

7Y 20 73*15' 73*10'

figure 1. Test site locations in Burlington, Vermont. area.

monthly normial temperatures dieterm ined tfrom Water temperaturesdata (ollet ted since 1893 V 1 hus, re( ent ( RK I ( let ent ly ( 1974 1978) begain to meia suretemperature trends bet anie apparent (I able 1) v, inrtert inme w ater tell)percJtitures o n Laikevthese will be liscusSetl later in this report ( hamiplai In he Lake Champl ain T ransportat ion

(ommen tog on Decemiber 1974, CRRf L in- Compainy at the Burlington f'erry [Jotk (fig 1)stalled an instrument shelter and] a water has tabulaited daily water temiperato res siru (

temperature remote ret ording system on Lake J uly 1962, with the ext eptio oft0 the months fUSU-Champlain at Shelburne Point. Vermiont t his iii- ally lacnuary-Mcirc: h) that the lake has b~een it vstrumientation was installed to monitor the ther- covered Monthly average water temperaturesmal structure of Lake Champlain (Fig 1) A were computed for these data I iing-termhygrothermograph provided a ( ont inuoLIs monthly water temperatures (17 years). in-record of air temperatures at Shelburne Point c Iud ing standard deviat ions, w er e ci Isofrom December 1974 through April 1975, cand calculatetl (Table 2)from December 1975 through April 1976 lIn cidd~tiof to flt, m hIN cisvtr~igi's. graphs

In November 1976, the meteorological station were incide of the %%cit temiperaiture riatl ngswas moved from Shelburne Point to the Grand tciken on the 1st and 1,tii t 01 c( h miooth tor theIsle (Gordon Landing) Ferry Dock at South Hero, years 1902-78 H-owevi'r, ii cinalyziig these, cotci.Vermont. A Doric data logger, with a water it sv aS 10110(1 thcit yeacr-to-ve'ar 55 ctter ti'0iIrtunLi

temperatu re profiling device, aittached by cable tILuc Wt uitons hcive little et tet t on the dtetis o1 (i

to a buoy approximately 100 m from shore, was iorition I hiis, these diagramns were oiniittedcalso installed. The Doric data logger provided a ex\cetit for tvo ( or'.es thait deimonstrate' the norprintout, every four hours, of ai r tem perature, ia I rcinge o1 wa cter temperatu Lre t hat miiight hi'and the temperature profile from the Surface espec terl cand the cavercagei' ur\e (f'ig 2) f1 gore2through the ice d~own through the water and into gives an ecm.elope ot %%,ater tecmperaituores thatthe Mud, where the cable with built-in thermis- ,i-i b~e extieriene 'd (uring aii ve'aritors was attached to the buoy anchor. Thisequipment \,%as in service on Grand Isle for the Closing and opening dateswinters of 1 976-77' and 1977-78 the Lcike Chaimplain Transpiortcition ( oni.ios

also provided invaluable data from their ticrr\c

Freezing degree-days log records (1 900-78) of the r losing and( openingDaily temperatures were used to ( ornpute ac - dacte's of the f'erry at Granti Isle, these cire shoec n

cumulated freezing dlegree-dlays for the wvinters in Tcable .3. 1 he dates shown, espe-i all the ( los-of 1960-78 at the Burlington Airport, for the ing dates 01 the ferry, servedl i5; the hcise daite,winters of 1974-75 and 1975-76 at Shelburne for many of the calculations performned for thePoint;' and for the winters of 197b-77 and 1977-78 prediction of ice formation cand de( aiy onl theat Grand Isle. These accumulated freezing lake The average number of days het"ween ( los-clegree-dlays were then fed into a Computer pro- ing and opening of the ferry approximate, thegram at CRREL; the resulting curves are shown in number tof days ncavigation on the lake is re-

Appendix A Mean daily air temperatures were stricted clue to ice cover.entered into the program and accumulatedbeginning with the first date that the mean dailytemperature remained below 00 C. Furthermore, RESULTSeach graph (App A) illustrates the accumulatedfreezing degree-days experienced during a par- Air temperatureti(.ular year, as c ompared with the 19-year 1 Ihie primhary ionji' tie( for aniiiciI /rg cii tein-

average cumulative winter curve and the 310-year Iierait res wvis to (il ilciti' I the toC/Ing deh'gi

normal curve These curves demonstrate year-to- days A tiirthi'r use o1 flte air teiimperitore, %%',isyear air temperature fluctuations and (ommon toi test fli h Pttlesis (Nee Anals sis. p 8) t hit

tendencies In addition, they compare condli- sumerVsc' i air teiipircittiri's might lit-

tions at the two CRR[ L sites and the Burlington oi' tormact ion thi' tol lossimg 5% int('i IHiss is ('1Airport F inally, they were used in the ice predic - I ahli I also ho1tst r-mtts simnie lilti'ristmIng t renidstion methods to be described later in the report. re'sult ing fromn Ih l i tViI II tIire, ret urils

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I J4iire, 2 tater temperatures at Lake Champlain. Solid line is average lor Years

Table 3. Data tabulated from LCT Co. freeze-over and open dates.

I t. i er date., pr, id'd l lake (hamplain I ransportaton (.onijianN (L(I 1 temr)perature dati troinl

Btlrlingtor Airport \'ernont

( Iii,'J dates [reeling Date lake I reelin g

;frie/v-oser ()pen dates Days lake degree-davs 10( 1 cornpletel4 deree-da s I(at terrs I Ierry start] closed to ice comet tro/ e to close ot entire like

8 Ian 60 2 Apr 60 85 260 Did riot lose1(1 Ian W1 15 Apr 61 89 130 27 )a n 61 561)

vI )e W1 14 Apr 62 104 180 16 1 eb 02 641)0 [Dec 02 15 Apr 63 107 220 8 t ib ' 580

(1 Dec 63 26 Mar 64 87 290 Did not (low15 Jan 65 15 Apr 65 91 3(X) Did not los'

2, Jan 66 25 Mar 66 59 310 7 te 66b 480

t, Feb 67 5 Apr 67 59 4(W} 1 6 Feb 7 51)5

8 lan 68 3 Apr 68 87 340 10 Feb 68 7709 lan 69 8 Apr 69 90 425 2 Mar 69 7815 Jan 70 19 Apr 70 105 17(0 21 Jan 70 b5)17 Jan 71 27 Apr 71 101 550 2 [i-b 71 761)29 lan 72 26 Apr 72 89 405 10 feb 72 5109 Jan 73 16 Mar 73 67 310 21 Feb 7. W1(17 Feb 74 26 Mar 74 48 480 15 feb 74 57(

4 Feb 75 29 Mar 75 54 370 21 ehb 75 52)13 Jan 76 .1 Mar 76 79 370 Did not (lose28 Dec 76 21 Mar 77" 83 250 18 Jan 77 49016 Jan 78 8 Apr 78* 82 320 1) feb 78 6(W(1

Average

15 lan 5 Apr 82 342 11 Feb (0.1(- 13 days) (± 13 days) (+_18 days) (_+87 deg-days) (+-12 dai,) I-±99 deg-davs)

(CI ferry navigated in i(e (over these two winters

b

t irst, monthly air temperatures exhibit the (u ves (on( erns the (omparison between

smallest standard deviations during the sumnier varIOUS stations near or on I ake Champlain I hemonths (It.le through September), whereas the air temperature re( ords of Shelhurne Point, Vergreatest range ot flui tuations oc urs in the mont, were ( ompared with those of the Burling-(oldest months of the year (December through ton Airport for the wilters ot 1974-75 ind

February). Second, air temperatures show a re- 1975-70 In the tirst winter. Shelburne averaged

cent slight (ooling trend for Burlington (Table 1). 97 fewer treeing degree-days 0C than B urlilg

However, there is negligible difference between ton. ido 202 fewer in the 1975-76 winter (App A.

the mean monthly temperatures for the .t)-year |igs Ala-A17b) This is explained hy the per

peood ot 1941-1970 and the mean since 1893 As sisten(e of open-water areas later in the k inter

a result, these long-term average temperatures near the Shelburne Point measuremtnt site l and

for the two periods are essentially the same. by the larger geographial size. width inddtpth

6 90C (44. 50F) ot the lake in this area (Fig 1)

In contrast, air temperatures for the past 17 In the winters of 197677 and 1977 78. a ,imhilir

years hae averaged 0.5(C colder than the long- study was done, Utilizing data from Grand I,,h.

term averages, or 6.4°C (43.50F). Records for as the CRREH measurement site was mo,t.(I tril

every month, averaged for the past 17 years and Shelburne Point to Grand Isle in the tall ot 1'47f)

compared with the 30- or 85-year average, The Grand Isle freezing (legree-davs data. when

showed slightly colder temperatures than the compared with the lurlington data, shoux a (Jlit-

30-or 85-year average. One item that partially ex- ference of only 45 freezing degree-davs 0C in the

plain,, some of this temperature difference is 1976-77 winter, and 105 in the 1977-78 winter

that the meteorological station was moved from (App, A, Figs. A18a-Al9b).

downtown city offices to Burlington Airport in It has previously been established (Bates

vlav 194 3 1976'; and Bates, in prep,iration') that thenormal winter temperature curve for the Burling-

Freezing degree-days ton Airport approximates curves for the

The freezing degree-day curves in Appendix A Shelburne Point and Grand Isle measurement

also illustrate the ret ent cooling trend. The "nor- sites. Therefore, the difference in the annual

mal curve (30 years) begins on 1 December and plots from site to site must be attributed to the

peaks around 690 freezing degree-days °C. In tempering influence of the lake This is espe-

contrast, the 19-year average curve begins on 16 cially apparent at Shelburne Point, which is

November and peaks at 810 freezing degree- situated between a bay and the main lake and is

days OC. This averages out to a daily thus more sensitive climatially to the lake's in-

temperature difference approximately 0.5 0 C fluence. In contrast, Grand Isle is situated on a

(10 F) colder during the winter for the past 19 large island in the lake, but its shoreline and sur-

years than during the previous period. roundings are more typical of the rest of the

Excluding the data from Shelburne Point and lake. Thus, the data obtained from Grand Isle

Grand Isle, a wide range of accumulated freez- probably more accurately represent the winter-

ing degree-days C has been reported since 1960. time climatic regime of Lake Champlain.The greatest number was 1125 freezing degree-

days in the winter of 1969-70 (App. A, Fig. All), Water temperatureswhereas the lowest number was 700 freezing On the other hand, water temperatures, as ex-

degree-days OC in the winter of 1973-74 (App. A, pected, do not exhibit the extremes that typifyFig. Al 5). Other pertinent freezing degree-day OC air temperatures. The average monthly standardinformation is summarized in Table 3. For in- deviation is 1.00 C (1.80 F) for the 17-year period

stance, freeze-over at Grand Isle normally oc- (Table 2). The largest month-to-month increasecurs at 142 accumulated freezing degree-days occurs from Mjy to June (7.3 0 C) (130F). TheOC (± 870 degree-days), whereas final freeze- average date of the warmest water temperature,

over of the entire lake, in the winters that ex- 23.8 0 C (74.80F), is 31 July. The waterperience complete freeze-over, normally occurs temperature slowly cools in late August and

after 603 freezing degree-days OC (+ 99 degree- September, then begins to drop more rapidly asdays). winter commences (Table 2; Fig. 2).

An additional use of the freezing degree-day This rapid cooling trend leads to the freeze-

\7

ANALYSIS: ATTEMPTED METHODS Of fi jImit' \iij~ti't mdii 1 .1,171 hut ,l

Predicting air temiperatures "t ' liilil1tl 1ilt' of flit-ellts ~tlt'ltt~

ri Ilt l.1 d I lrd 11 1 rI(t-. fIo 1 11it J)d t, id ?(ililt. f it Iitio t U tiit*f W ik II s liiid vu t

ti-eogir ttir I]- tor s at v s I- the i--i oi- t foo Itfill lit'l 1114 11 1ii lii t %\,I, ti ilili'e 'N I

ura 1 t , ot jr-ii tilig 111 toIS ltl f iii tlil't'1,1, (1-tI "m n fSillt vIf ttl li j1'ratnris t. i tiil l rf ithiin atiot\, it rid-empert gerIt' nia ns ofe tine lIli (lit ti'l7l 1 t'ldtil 1197/4it tfl i t, 1 liv'et

tvgi l ea u t (li re-dat ill 55 rt tos ib Itt f lirt [ll tfill, ( lI( I' (m f t 5 ( I tibl i ll

IgLrtl ta( l k(ii at, IgIi o m ti % (Ianadav Ie n Iii IIIti' t%11 1 1 %\ dI ttlW 11)(.1t fflit ll",s I lpl 1'd (1,I

re i-i tiil--lj inieaed Relt-irs tirl I-rat I her.n it~ telt~t i dlii I i the al l (ot 11171 A il'

mtiir s r i Sedi f o h ~tii))erdtemr a lture t~iigt-lt-iuis (i dic 11 ( ) u-'If~ ,rI) fuistllil111, 4

tiit Iak s itngtiri asi-ra ttor W lIrIIItILIC k\irvi)t dat 1115 11w tti i (ofi tt'rS I2 isflirlji Ill

iiionsr e no dki M'ictijid U t ilas i th s (it-rimed i ()9s75e i titrhd i't- itt- i it-Ii tdi 4 i

Ingari I-le in dvgrc liiiit' of- %\ IA thi 3o dall ii) Lth I'le tiIruifi( hidI ll it highes \t -\1ut-lak flq~ , ,

Ile iirsd (lteni t hod fo(r. although ting IItiehoi 22 8 t(7 10 it (' i d ,1(. it irlt, d 9/5 1eiti tiit'

iiitin I lit, r- llat r t e\o nijii'rdtirc es t r ed I31 Ilii otl('li.

iha ds dll g f lit, e ot illeipage 9i)s riiler (Ii ths, in stilliilart, I unm (, tl t ' te10,1'll Ie !hie

ro rt ard tht(I Ill1 t( td, dsir tehii'tie nied' J ] 117-1 7Iii Ldk (t'hd11WMIiai 1 III( little ha l

teltios ip ar e nut vlit i-sat, rqu i enl( t (itt IA ate toc i'fii t ti e II c iii bite ()I 114-- ie I ill -I-

Mid itk, of alln NS 11 tlod V~j 'ttelite dutlarall sin ieti, ted, 55 Itr ttilrt, I [( is

Sumr wc~ oat rso temp e rs~ d t Illd idI~ it,' (lepelWsIf)tl (llbV dir ( te\VjeI tflehi it'fi he terni a\tnra( t or lit lngo d Ae I i roit, Vdloingi - da(tte i o tf flthe ,-rail jutI toire Iht

perient il ty ir tett). erte o trddldt(it i t en ie ( lill f rtls (1Ltrc i11 h

w"ri dIs le [it, h( oniogaj%ihil 3 itt sng t hei ~ Fl t e r temperatures an hd ireezige1 ) )

laker\c I m hi tililis ire athoug tit-, m e(lth ot degre7e-days g2 o 0 ut.175 AJLIleit oii urn-lu I higr e re e ur i otiM l djUro( it nol peak o thme rIaiti-i n I s n, o unti180ri74 1[ i

fuli,i mkanlni- do l i m tho ll ]-s( dter tejirdirfli-, Ill iti th Ihtigtrt Llinicr~it t Naoli tieh temls ds redre o (In dlre t lii I Iuisiligda tti-, o the G1(rand thus tMSar, td n ~ Lak e d m li n e litore bhiet ing~

I-t -rra t, (tree/ tI--o v e r, r(~ re in Ito i %% i urti-,mp e dli~s I1lit tie Dc tl t tIlII(

Sumerwatr empraure nritin depedet riii-i air ti-ieratUre hat W

I e henil irl trvof(Ila e smo t~IIl- ar~ihes( nili aeth o erllIMt8r

niar tl \ the 17 \,i , i n0iir , I, sil , t ttllt al , ir rtll' 40C ( 390 F) water temperature as a base, freeze-

rtepi ,',ntatl , t ret t t trends, 1n .at ( Urt( 7 over will occur 17 days ( ± 6 days) and 150 freet-das) ( losing date, an be ptvd( red a ilorioth ing degree-days after the lake rea( hes 20(Caheaid I he model ilm rlrurates, % ati ttinpt'ra (360F), and 8 days (± 4 days) and 70 freezingtlt ' ll. l''t'/llg dt'gree-daS Ill Ihe d(eterllllna degree-days after it reaches 1 oC (340F) (Table 4)twin W the i ii1t h( r ,hl i' IiN ( los it, rminltirriiig4 There is the advantage of more accurate predic(-ilhos,. the daLt Wi itt' uI)rlnatl(in art Ibe molt' tion with decreasing temperature However, theit'l\ piinpitrn td as it apijirroat Ites decreased accuracy in using, for instance, 40C as

The dates of the occurrence of these three the basis for prediction is compensated for byparticular water temperatures in the late fall- the fact that a forecast of the closing date (anearly winter were of interest. Of primary impor- be made further in advance (29 days versus 17tance was the date the temperature of the lake and 8 days, respectively). See Appendix B for acooled to 40 C (390 F) and remained at or below combined summary.this temperature. The first temperature limit was The significance of the accumulated treeiingchosen because 40C is the temperature at which degree-day curves for an area is that if, for somewater reaches its maximum density and the reason, water temperatures are not available alake's thermal profile is nearly isothermal at this freeze-over date could still be approximated bytime. The average date of 40 C water matching a previous winter's freezing degree-temperature is 19 December; this corresponds to day curve from Appendix A with the start of the100 freezing degree-days (App. B). Oa the current winter's accumulation of freezingaverage, 29 days (± 7 days) and 250 freezing degree-day data.degree-days elapse between the occurrence of In a further effort to more -1(.( Uratel, estlmatethe 40C reading and freeze-over at Grand Isle a (losing date, two actual a (LimUlated freeting(Table 4). This represents an accuracy range of degree-day (urveN (App A) (for 1975-76 andalmost 75% (Table 4). Therefore, it can be 1976-77) were compared at 2°C (360 F) and 10(estimated that, when the water temperature (34'F) with (Urves of similar shapes and slopesreaches 40 C (390 F), freeze-over will occur ap- through the end of Dec ember, rather than withproximately 29 days(± 7 days) and 250 freezing the normal curve The 1975-76 curve "as coin-degree-days later. The results of this prediction pared with the 1968-69 curve, using the te(h-method for each year are summarized in Table tnitUe previously described. Likewise the5 1176-77 (Urve was compared with the 1462-63

From the calculations shown in Table 4, it is curve The results, shown in Table 6, demon-evident that when winter air temperature trends strate that these approx irrat ions do not repre-are colder than normal, thus accumulating sent any signfi(ant improv ement over using thefreezing degree-days at ti taster rate, freeze-over normal curve.oc curs from 1 to 7 days earlier than normal. The Finally, observations from other stations w5 ereaccuracy of this i(e prediction model is ex- examined in order to deternmine sshether the(ellent ( ± 7 days) when it is noted that other im- dates of the ice formation preccted b, thisportant meteorc,.ogical and mechanical factors method hold true for other sites on Lake Charn-have not been considered plain The approach thus tar used air tempera-

However, as a further demonstration of the tures from the Burlington Airport and wvaterice formation-freeze-over date at Grand Isle, the temperatures from the Lake Champlain Trans-same type of analysis is presented for water portation Company (LCT Co.) records 1 herefore,temperatures at 20 C (360 F) and 10C (340 F) air and water temperatures, as well as observ-respectively Appendix B summarizes the ances of dates of ice formation, measured byaverage dates and corresponding accumulated CRREL at Shelburne Point (1974-75, 1975-76) andfreezing degree-days for the occurrence of 20 C Grand Isle (1976-77 and 1977-78), were compared(31 December, 200 freezing degree-days) and with the water temperature data from the LCT10 C (9 January, 280 freezing degree-days). In ad- Co. files. Comparisons between water tempera-dition, the average number of days from those ture of 2 and 1 OC and actual ice formation datesdates until the closing date of the lake at Grand are shown in Table 7; this analysis and Table 5 il-Isle were also calculated (17 days and 8 days, lustrate the validity of the approach to icerespectively). Table 4 summarizes these results. predin tion for lo(ations on Lake Champlain For

Thus, similar to the predictions made using the most part, the dates ( orrespond within a dav

i I9

Table 4. Days to closing of ferry at Grand Isle due to ice after occurrence of4, 2, and 10 C water temperatures.

Date 40( No of ila s Date 2( No ot da(Is Date i1( No of dalI (9°h to l /ose I ((hol j to (lose I W40) to ( lose

192-tB 12 Dv 18 15 IN,, 15 2) 2 [)(, 4

19 61-64

1t'64-65 17 De( 29 7 Ian 8 11 Jan 4

"#65-6Oh 1 Ian 25 8 Jan 18 1 i ]an 1 t

1l66-lb7 1 1an it6 18 jaii i8 t0 a111I 7

19b7 168 18 Dit 21 21 l)i, 18 , lan S

1968-69 10 Det 10 21 Di, 14 27 )v( 11

196-701

1970-71 24 De( 24 8 Jan q 11 Ian I

1471-72 20 D 40 0 fan 2 19 Ian 101472-71 2 Let 18 11 Di , 29 6i Ia I

1971 -74 17 Dvi 52 11 Jan 25 21 Iiin 171974-75 25 De( 41 21 Jan 14 22 lan 111975-76 19 De( 25 29 Do( 15 " Ilan 8

1976-77 1 Dv( 25 15 DO( I 1 22 Det 11977-78 2b Dec 21 It l),( 17 10 1 ln 4,

Average 19 Dec 29 ± 7 days 11 D.( 17 ± (i da v 9 Ian 8 ± 4 days

Table 5. Predicted freezing degree-days and closing date of Ferry as compared with ac-tual, using water temperature occurrence of 4, 2, and 1 0 C.

Estimated horn I stiniated from I smtiated from4-C (?9of 20( f(f6,

0 10( 1140f1 Actual

Closing Zo

. Closing Z°

Closing Z°

0 Closing Zo

.

1A inter date to close (late to close (late to close date to close

1962-b3 9 Ian 245 1 Ian 210 Ian 230 30 Di( 2201963-64 Inufi( lent water temperature data 31 De( 29W

1964-65 14 Ian 350 24 )an 75 19 )an 320 15 Ian X)

1965-66 30 Ian 360 25 Ian 10) 21 Ian 280 26 Ian 31i1966-67 30 Ian 441 4 feb 410 7 Feb 41) 6 Feb 4M)1

1967-b8 16 Ian 360 7 Ian 260 10 Ian 30W1 8 1an 14O

1968-69 8 Ian 380 12 Ian 191 4 Ian 120 9 Ian 4251969-70 Insuffitlent water temperature data S Ian 17(01970-71 22 Ian 500 25 Ian 54 19 Ian 510 17 Ian 551

1971-72 18 Ian 390 23 Ian 410 27 Ian 410 29 Ian 4115

1972-73 31 Dec 320 28 De( 250 14 Ian 31(1 i Ian tIl

1973-74 16 Ian 283 10 lan 41(1 29 Ian 441) 7 Feb 4 1

1974-75 23 )an 170 7 Feb 390 30 Ian 140 4 Feb (71

1975-76 17 Ian 120 13 Ian 151 1 1 Ian 15 11 Ian 1711976-77 1 Ian 280 1 Ian 280 10 Del 2511 28 Dei 2511

1976-77t 1 Ian 270 1 Ian 240 i0 De( 21M 28 )e( 25O

1977-78 24 Ian 410 16 Ian t10 18 Ian 130 16 Ian 121

Z = Freeing degree-davs (OC)

t CRR[I Site

10

Table 6. Predicted closing date of lake for two winters from a similarwinter versus "normal."

tstimated fron Estimated from20C (360)F 1 OC (34OF) Actual

Closing Z °. Closing Z0 " Closing Z ° "

Winter date to close date to close date to close

1975-76

From 1968-69 13 Jan 370 19 Jan 440 13 Jan 3701975-76

From normal 13 Jan 350 13 Jan 330 13 Jan 3701976-77

From 1962-63 31 Dec 300 26 Dec 230 28 Dec 2501976-77

From normal 1 Jan 280 30 Dec 250 28 Dec 250

"Z = Freezing degree-days (OC).

Table 7. Comparison of water temperatures and ice formation at severalsites on Lake Champlain.

DateSite Date 20C Date 1( ice-covered Remarks

1,1 inter 1974-75A Burlington 21 Jan 22 lan 4 Feb Ferry (Iosed, Grand Isle

C(T Co )B Shelburne Pt - "-24 lan 4 Feb Ike formed. Shelburne Pt

(CRREtL

V1 inter 1976-7tA Burlington 29 D( 5 JaSn 13 I an Ferry (losed, Grand Isle

(ICI Co)

B Shelburne Pt M0 [)e( 6 lan 14-15 Ian lie formed, Shelburne PtI(RRF L)

V1inter 1976-77A Burlington 15 De( 22 Di( 28 De( Ihe orned

(l." (;o )

B Grand Isle - 21-21 De( 28 De( lie tormed at re(ording buoy,(CRRt L) Grand Isle

C Shelburne Pt - - 10 De( lee formed, Shelburne Pt

Winter 1977-78

A Burlington 1 De( 10 lan lb Ian Ike formed

RC I (o)B (,rand Isle 28 Dec 14-15 Jan 10-11 lan Ice formed at recording buoy,

(CRRMI Grand IsleC Shelburne Pt - - 16 lan Ice formed, Shelburne Pt

11

or two to the (losing da~te's ot the terry or vhen it w bert r is, theill an orrelatiori. 11 is thet number

would ihIVe been ( loseCl due to perilhanent of input '. aloes alld 1 is the' "tuml (t the squ1.ares

treve ' ve r of(ilt- rank ditireniisa t I he abiove' expreslot)1, USIng tilt' (1,11,1 111 1 aille 8, ri(lIi el, to

Wind speed influence on closing of the lakeAs erage dadi ind11( speedIs (mn s- Jwere 1( - or0

umutlated em( h tall, starting with thet (Lite ot 0i840 1t01C av erage dai lx aiir temperature 0( ( Lrreor v Rank t tirrelation )rQ 1 2until thet terrx losing clate due to i( e tor eai( hwinter fronm 19)54 to 1978 1 hese vailues gise the I he dirilx ses show, n in F Igunv and I alble 8,total tw 0(1 run (luring lake cooling below d baseW Mid the, similar (orrelation (0(11l I( ientS obtain(,dot (t0C air temperature for each wsinter I hitse bx both imethiods, indii ate that 1) atter air tern-

s aloes are shown With a( ( umidted freezing lper,itcire, w 111( speedl is prohbiblx thel, next most(legree-(lays base (O0 C) II asending order in signili( ant s ariable in tpredli( tion ot Ic e torma-I able 8, for the purpose of ranking amiikiyis. tin da~tes, 2) a greater numb111er ot freez'ing

w i b will lbe cisc ussec later in this se~ tion (lcgri'e-(lavs art, neeled to ( lose navigaltion onAs mixing by windl appeared to be the next sig- the lake it "Ind speeds are high -in other wsordls,

nit itant Variable in predi( t ion cot t rveee-over, t reie-over is more likely to 0( (i Ur w~ithb lowerwinmd vaIlUes (Independent variables) were thin wind( speedls aind (old1 temperatuiires, and 3) at ter(,orrelaited w Ith total a( ( umukl ated tree/Ing the lake is ( ooled to near 00C, strong winds

(legrce-(laiss trom table 8 (dependent variable) dlelaN, the o( ( urren(e (ot t ree/e-over on a largefor c orresponding Vear's iisirig a (OmIUter regrcs- lake SuJ( h as [Lake C hamplain When m('c( hanim alIsion arnalysis tor eCd h winter I he resulIts and a mixing of the surf ane area ot a lake is redoc edonipoter plot aire shown it) in-gore 3 during low winrd speeds, and( 3t)L freezinog

1 he formula uisedIS is egree-clays have been accumulaited (I able 3)00n

Lake Champlain, the nest (0o(1 air mass w ith lowa= atbx wind speeds will most likely induc~e freete-over

where =accuimulated freveting dvgree-days, Water temperature vs surface air(0Q) until ice formation aind x accum1ulated temperature analysisaverage daily wind speeds (m S-') until ice for- To relate the water and surface air tempera-mation The computed Values of a and b are tore analysis for Lake Champlain to other largegiven in figure 3; Figure .3 also gives the lake areas, the report "Lake Ontario Atlas: Lakecalculated correlation coefficient (r) of 0.63 be- Temperatures (Chermack 1977'') was obtaine~dtween accumulated freeuing degree-days and This report gives average monthly lake and sur-accumulated daily average wind speed. face air temperature variations near two sites,

The ranking order of accumulated freeting Rochester and Oswego, New York, on Lake On-degree-days to closing of the ferry (a, Table 8), tario. The pieriod of record covered was 18 yearsand the accumulated average daily wind from (1950-1968), or approximately the samie numberthe starting date of freezing dlegree-clays (b., of years as the Lake Champlain study. The LakeTable 8), are ranked against the actual yearly oh- Champlain water temperature data are from theservations of earliest to latest closing dates oif period 1962-1 978, which encompasses only 7 ofthe lake. A ranking correlation (Smillie") was the same years as the Ontario study; but thlecomputed for the data in Table 8, using the ex- analysis shows some similarities.pres si on: Lake Ontario, New York, temperature curves

taken from Figures 5 and 6 of Chermack" are

r 6~ 1:2 replotted in this report in Figures 4a and b. Then(n 2 -1) 'I air temperature scale is expanded to accommo-

date a similar plot for Lake Champlain, Vermont,for comparison. In order to plot the diagram

1h Can efrvoeae nietruhu thewnr, (Figs. 4a and hi for Lake Champlain, data fromt 17 nd Is78 bI ervj,itin ihnne throughu the wnterss Tables 1 and 2 were used. However, water

it' (over tI'dws' I temperatures were not measured under the ice

12

Table 8. Ranking order of accumulated freezing degree-days and ac-

cumulated wind vs closing of Lake Champlain at Grand Isle, Vermont.

I v jt o tedts -\(wal

I , - t t, ,.. ( II ,4(,,J -, tnM n l ,aItl' t to late'l lRinkit

/I0 dj .S ' r" -11W a Staff /1, (1.J4S to 0JO I J) h,:ng. of( lk,' (Ti 1 1) d

h 4" 144 11162- A o 1197 -77 t 4 i

(lo2 h,4 _204 1 to,5-64 124 1462 6 5 2 1 1

1976 7 244 1 '476-77 149 1oo1 62 1 4- 4

19 5'4460 2o0 N1l -62 107 196 1 64 , 2 I

l0 64 2) 14(9-70 171 1(4,'t4-7 701 5 7

1464 6,5 41444 1'44,4-h61 175 1 ')5) -4 M 4 8 4

'072 -4 II() 1475-7, 1840 1% 7 - 68 11 11-44S14,7,h l'o t) 10 159-60 184 1968- Wj 17 14 11'17,' 748 4244 1470-71 I') 1472- 74 7 12-5

I(0,4A) 6 1 1i4 1977 78 2400 1 ')60-61 10 4, 4

I(117 18 44 '467-04 24, 1175-7t5t 1 7 o

Ili(hM 74 4744 1472-7 1 210 1(9,4-4,5 0, 1 1-7

1177,-70, 17o 1464-05 244 ('477 78t q 14-1

11174-75 ,744 14,8-0) 2 i1 1970-71 I' 9 104

'lhh4 .7 4444 147 1'-74 274 1,'65- 06 8 17 9

('471 72 4445 19604-07 297 ('71-72 14 ('9-1

196h8 , 425 1' 4 -4, 4, 5 1')74-75t 14 18-4

l17 1-74 484 1to74-75 425 1406-,b7 15 lb-1

1970-71 550 11471-72 lot N'71-74 18 15-4

/0 1 rviv/i dvgrvv-da,1,,

t ( R iI I ,,bser% ed ( onitions, d1ur t ShC'e .Var,, J .O, thi t(rr\ opleried during thi entre

vllntvr, ot 14)76-77

( Io ng dat re he, (etr( nornlIl, M, ld 11,1'% (Io'etd

600•

~400

41

0 too 00 30W 400Acmurlmated Wind (X)

Figure 3. Computer regression analysis plot, Bur-

lington Airport Data. y=a+bx, a=188.4, b=0.654

and correlation coefficient = 0.63

13

24

24 1 1 1 1 ' 1 1 1 1

. o- 1 -168 (ROchester NY) J 2o -o- 1950-1968 (Oswego, NY.) Jul

-'962

-,978 (.urliglon,,,I,) S@PK16.. 92.|-r u ntn -

16~i - 1962-1978 (8ulnln .t0)n,

SS12

100

JOn

'wuono" 0

612 -8 -4 0 4 8 12 16 20 24 12 -8 -4 0 4 8 1l . 16 2024Aver e M onthly A ir Tem peratuee *c )

A verage M onthly A ir Tem per oture ( *C )

a.- bJV 6 u

figure 4. Average lake water temperatures vs air tenperatures for Burlinton. Vermont s Oswego andRochester. New York.

cover most winters (January-March). A combina- The Burlington values are plotted on Figure 5.tion of the LCT Co. data for the years available Table 9, Figures 4a and b, and Figure 5 show that,with the CRREL measurements on water even though the mean annual air temperature istemperature of the past 4 winters is included in 2.10 C warmer at Oswego than at Burlington. thethe averages for Burlington in Figure 4. A slope mean water temperature on Lake Champlain isanalysis was computed of air vs water 0.6C warmer than on Lake Ontario. One factortemperature (Table 9). This shows the similarities that must be considered in this comparison isbetween the curves for Burlington vs. Oswego that Oswego (Lake Ontario) records are for theand Burlington vs. Rochester in Figures 4a and b. period 1950-1 968, whereas the Burlington (LakeTable 9 shows that the slope differences be- Champlain) data are for the period 1960-1978.tween months are the greatest in the summer Another possibility for this 0.60 C difference isand that the slopes of the curves are similar. that Lake Ontario has a much larger water

The curves in Figures 4a and b demonstrate volume that has to be cooled or warmed.the similarity between a large lake (Ontario) and Further studies on lake surface relationshipsa smaller one (Champlain) in similar temperate between annual water temperatures and near-climates. However, there are notable differ- surface air temperatures need to be completed.ences; for instance on a larger lake, the This may be a way of comparing one lake ormechanical effects of wind are greater, reservoir with another where no records of icetherefore breaking up the primary ice cover and formation or breakup are available. Also, it maydelaying freeze-over. Also, on Lake Champlain be an indicator of the length of the ice season.(Figs 4a and b) air temperature means are Finally, as previously stated, the geographicalcolder, especially in winter, and exhibit a greater size, depth and exposure of the water body willmonthly range than they do at Oswego and have to be considered.Rochester

on Lake Ontario.further comparison of Lake Champlain and Prediction of ice-out datesLake Ontario involved an examination of annual Freezing degree-days graphs were also used inair and water temperatures at both lakes. For an attempt to predict the opening date of thethis analysis, Oswego, New York, was selected ferry,(ice free at Grand Isle). The average date offrom Chermack" | as it is nearer in mileage to the maximum accumulated freezing degree-daysLake Champlain. The mean annual air is 20 March (App. B), and the number of daystemperature for Oswego was 8.5C vs 6.4C for from this date until the opening of the lake wereBurlington. The mean annual water temperature computed. Approximately 15 days (5 days)for Oswego was 9.00 C vs 9.6C for Burlington. elapse between the date of above 0 C average

---*

14

i9

C 0

8.0-0,0

7.0

.4E 6.0

5.0I II i

11.0MissingData

1 0.0 Period Mean

9.6C

E 9.0S

8.0J I I I I I

'62 '64 '66 '68 '70 '72 '74 76 78

Year

Figure 5. Mean annual water and air temperatures, Bur-lington, Vermont, 1962-1978,

Table 9. Slopes of air vs water temper- daily air temperatures and the opening of the

ature determined from Figure 4. ferry. This figure exhibits too great a variation tobe seriously considered as a viable means of pre-

Slopes Burlington Oswego Rochester dicting an ice-out date. Since Lake Champlain islarge, other influences (i.e., solar radiation, wind,

Decl)an 0.94 056 0.57 water currents, etc.) also affect the rate of iceIan-Feb -1 60 -250 -2.75 deterioration. Further work needs to be done onFeb-Mar 006 0.03 0.04 the identification of these parameters and theirMar-Apr 0.26 015 0.16 influences regarding ice breakup.Apr-May 0.57 0.52 0.52May -Jun 1.30 1.05 1 02

lun-lul 2.42 2.32 3.62Jul-Aug -0.29 -1 25 -1.10 CONCLUSIONSAug-"Sep 0.62 0.62 0 58Sep-Oct 0.84 0.98 101 The basic data obtained on the annual open-Oct-Nov 0.68 0.86 0.85Nov-Dec 0.48 -0.44 0.46 ing and closing dates of the Lake Champlain

6.28/12 3.78/12 4.98/12 Transportation Company (LCT Co.), Grand Isle,Ferry Crossing made this report possible. The

Avg. slope 0.523 0.315 0.415 LCT Co., from 1960 to the present, maintained an

15

i'streivils at tiraite I otitt ori the terr ( ilsing Chamlain and ( ompared wsith I siiar anaiclysis,1nd( opening dte~ti ,i ' 11ea"r that art cssiiit'ili for I ike ( )ntario at twot lt atiofl' I i, slopesflte treeii otier ind breakup daites of flte I( resulting from this anialysis are, similar fo~r bo0thIoser or thi, area' or I 'Ike ( 11iampf~in t ake ( hrinipl~iin and Laike Ontario lndi( ations

I hese dma iiil ins 1ali II ie olipaed are that this might be a way of ( omparing one't at 1stt a .iIII) 0\0i h *s alt 55at er Itim perat tire reservoir's I( e ( over history with that of another'Ind hI. it111lolgit iil diti, for thet samei seas a where rin( ords of ( limiate and or waternea"rhs I aIke (, hamlipdain Io( at urns I ree/ ing tempjeratUres, ire available and dates of i(v f or-

dvgree-da is( uit- e( 01( ) iset) for eat h sear are, mlation and break up are una\,ai tablegik en In A~ipendi\ A iI(i h exNit pot his nota- Iurther heat budget Studies on the interd( tiolltlions of daites f tree/ti ter alt Grand lIle I oin- at the air water or itoe intertafte need to be om-pidte iketre/ 0s V1 and( Mt (urreur v ot ss iter pleted to f urther (onfirm the above' analysistiiiiperattie at 4 0( ( i) 0l )O( 1(0'1 and I0

t WtI )I rtoit tlie~t trte/ing degree this t Lirkes aint LITERATURE CITED

thiir asi iitd iitttrtion, it v torimation

d It es anld ItandIrI fd li' latitoll, "%'ri ptr'di ted I I A.- h lih. .I~i tItiii"T0"It,il I t, i til t tI I tot''-

%% It t o ( nsNItlrdi)h1hi-d' I i urns ( I ,i i I ) St i-ira I Iti, ., tI if ) ,q, ,,

mithods of predn timg Ii' tforimattioin on I ake f t~~tit I dI uitit-ti c.15 781 \jt,it

(hatuplair tsere studiedl the most Mt ( urate 11p- 1 ut Alf) -tittiti

proa h invol\,edtl ti tis't, t of j (olbillitioii of i Hat" R I ttA iti ittiI-nthu iIit -i

ss ater temperatures, and trett,'ing degree-daiys.I itttii .Ii IIk t Itompii"ttt 5 itO tm RCN-

the past 17 ss ilters are' (.Onsidered. a %%ater tern- tAlD ',02141,

peratutir ot 4'(' ( 399~ ) and 100) free/ing degree- L IDoparirnit 4iIttittt 11041 -11i \d,, .... I

this nottrttl1115 0( ( tirredl onl 11) Dve e r I htts, t Ii tot ,ilit it flit 1, 1, \i,t 81i it ki -i i Iiltrite/v.-oisir at Iraind Isle, Vtrmioit , (an he v\- tniiii,,, md- ~iti~t inl iit olmiu m ,,ii ii,,,

tplt till apprri\ilttil\ 21) thais laiter at nearl\y 1'30 dhun-i do\ NI 11tntdtitrete/mig degri'e-da% s O(, svhih falls normially, on S lt- NIiti1i t it 5511 ~ttd157 lanui~rv i, ih I Ntajndajrd deviation tot 7 dass Nttlliilii ii~tti S ittitt i

Althoitgh this (a 1(ulatloll is for Grand Isle, the it V ge 1471,1 1 1-- itiii

\,alue is, representativet (see Table 7) of other anigv tnt '1mg tl wi mdtii-~tii ii i

areas ot the Ilake [ inallv, this pritdicted date (15 utti If( ,ttttit ii )ut 1til,~ 1 utu.u~lutut~

lanuar,,) tan hi aipprosimated starting with thitit " I tilt t11 1 \11 '111itttttMIIiti I RI (A1 I NI 81

tisertige (late of 0( ( OrrentI' of 20C and I O( - Iili-Iti \1 A 1101t

i, I (titiliut gtfiist jinld d-i% ,t -

vsater temperature. whiu h :orresponds to 200) SuitIt ifi At if,s Ar,,t It I ,tL,ilti\,m\tti

and 280 freel ing degree-days OC, respectivetly NttiI iit iA)iSi

Analysis on wind speed influerce on the ice i1\iT liii tituult IIiI ,'diti(NIIN'i iNiitcove fomaton f Lke hamlai wa mae Li2 At) 44,8i74

co erfo ma in f ak C a plin wa m d Niti X' I I ti (Jfl th rc' i',ilii iii~ Itwi itt ii

for the years of the study A computer regression feiit,'Nit,' Itt. I( i. i loflIlil 1 it li'ltfanalysis using wind speeds and freezing dlegree- in .i'nslik Ilte/it \i0 14. ) l- 2012

days OC as variables gave a correlation coeffi- til tttillti. K 55 (1%b NYictlS inlmtitttni u i N, 1~ n-'-i in l

cient Wr of 0.63. Also, a ranking analysis (Table 8), , wiritiiiiit i' NI litit F~r- it-

using the same variables, gave a similar rank cor- I tii~tt lw-., kit Ii, 177 tit A,'htn,

relation (rs) of 0.62, indicating to the authors that On)tarm~ Aida, N, '0 O A 008iia greater number of freezing degree-days areneeded to close a large lake to navigation due toice if wind speeds are high. In other words,freeze-over is more likely to occur with lowerwind speeds and cold temperatures

Another analysis (Table 9, and Figs. 4a and b)was completed in which surface air temperaturewas plotted against water temperature for Lake

16

APPENDIX A: FREEZING DEGREE-DAY CURVES WITH ICENOTATIONS AND WATER TEMP'ERATURE NOTATIONS

1000 1 _I11000 ---

- ( Freltzo*ver at GSrand ie Ferry Dock - ( Freeze-Over at Grand isle Forry Dock

.S eo Lake did not clos so( -800 Z) Lakre Freeze-Over-oNo water temtperature data No water temperature data

-

.600 i600

!40040

1959-960- 1960-1961

200 1,--9 Year Average 20 - - 19 Year Average

Z ---- Noml--- Normal

9591960 1960 1961 ______

Figure A Ifigure A2

1000 1 1 000 1 1

0 - ( Freeze-Over at Grand Isle Ferry Dock - (D Freeze-Ovr of Grand ile Ferry Dock

.8 Boo0 (2) Lake Freeze-Over - ~ 80 ®Lk reeOeoNo water temperotare data Bo- Lk rmO~

O - ® I2C water Temp --

*600 -600 4 T4CWater Temp0.

!40040

1961-196- -* 1962-1963--i 19 Year Average 190-,I Year Average

-- -- Noma -- - Normal

Nov FebJ. 1 Mar Apr ov DC Jon Feb Mar Apr1961 196 962 1963

Figure A3 Figure A4

1000 1 1 1 1001o

- (D Freelze-Over at rand ie Ferry Dock - (D Freeze-Over at Grand isle Ferry Dock

Bo 80 Lake did no Clos 800 ® 1 C Water TempoIncompletle wateir tortri. dalia~ 2-C Water Temp.

-- ------ 4-C Water Temp. - - - - -

*600 600 Lake did not close7

p400 p400

A 7- 1963-1964 a0 9416-- 19 Year Average 20/--19 Year Average

200 pr'd S 0rdo Normal ---- Normal

U-

0NOV e Jon Feb Mar Apr Nov Dec Jon-t Feb Mar Ap1963 1964 1964 1965

Figure AS5 Figure A6

17

000 -- T1 - -T -- I000 ---------

* ® Freeze-Over of Grand isle Ferry Dock ®Fez na rn aeFryOc

2 800 (2) L01141 Freeze-Oe - -- 800 - 2 Lake Freezip-One,U (1) 1C Water Tern () 1 C Wale, Temp.

o ® C Water Tm * ae Temp. ----- --

-600 4*C Water Temp -:600 V~ C Wtle Temp./

400 ~400 '

a~, 1965-1966 19697200 ,"- -19 Year Average _ 19 Year Average

C 0Nov De -Jon __Fb a p Feb Mar Apr

965__ 1966 1967

f igure AZ7 f igure AB

1000 - ( Freeze -Over at Grand Isle Ferry Dock 10 --- 7

(2) Lake Freeze-Owe (DIj~ Freeze over at Grano isle Ferry Dock(3) 1 -C Water Temp. S80 ®Lake Freeze-One,

800O (1) 2*C Wale, Temp. 0 TI*CWtrepV ( C Wale, Temp.U

------ -- ---- o 2*C Water Temnp. ,-------60 - ®4C Woer Temp

600

m400 400

- 1967-1968 a - '968-1969

19 IYear Average 201' 9 Year Average

0oma ----- N~-orl ]

Nv Dec ion Feb Mar Apr Non_ Dec ___on Feb__ Ap

M97 1969 ______

Figure A 9 Figure A 10

1200 1

(D) Freeme-Over at Grand tsle Ferry DockI

K)O_() Lake Freeze -Over 100 ( Freeze-Oner at Grand aley Ferry DockIntsofliconzt water 1".Y data 3 )Lake Freeze -Over

1 -l C Water Temp.9 00 - 800 V2C Water Tem.

0 (Sl) 4-C Water Temp. ---

l!400 ~400O/ - 1969-1970 : // - 19 Average

200 - 19 Year Average -w NM IerAnrg77 ~~Normal: Mrf

Nov, Dec Jan Feb Mar Apr Nov Dec Jan Feb Mar A-e1969 1970 1970 1971

figure AlI) Figure A 1

18

1000 (0001 T

(D reere Ove of Grand Isle Ferry Dock ® Fez-vra rn seFryDc

Boo (54Catrep7 - 80 ® (2) L ake Freez O

I2- AtrTm.- - -- 9 @eo Aveag Wate -~ -- 9--e'----a

(C - Lo 0 00 I

200 19 Yake Averageve 19 Yea - 00 C) orFezeOe---- Noma ---atrTep ," -- - -a

197 193793 -<-A

(D0 I9o-De ata AGeaand iseFryDc reeOeraarn seFryD7 D 2 aeFez- Oovma 8 00 02 Lak (9 YearAverag

(a I -CWtrTm a f- ae ep

20 CW t qn - - -- -2CW trT mt --- - - -

(973-(974 (94 97 -9

2000 I oc

S~~--- 800ma CS La2Fez-ve 00 ---- (NoWaermepal

Fe ® Mar Nove Deoc JonApr-

0 0 0 1< 4hl ., e0 0 0B r g o

Bo - (971'CWatr9Tmp

400 40 /,'-A~tg7,'arAerg _ o1 YearAvrg

S 00---- Normal Sy( er vr 200 Noma

Nov. F~ M r p--- -Dec Feb ! Mar Apr194(7 975 1976

Figure A 16b Figure A 17a

19

1000 0G[ l F Shelburne 1000

- (D Freeze-Over at Grand Isle Ferry Dock - (D Frooze 0,, ot Gand Isle Ferry Dock

Soo ( lC Water Temp - - z 800 -. ) Lake Freeze-Over - -

1 2.C Water Temp ( Ic Water Temp

- @ 4 1 C W a e r T e m p .- - . .- - - - - - - -- ( @ 2 C W a l e r T e m p . . - -.-- -

600 Lake d d nal cl-e / -/C Wl60mp 4C water Temp 7 /

4007 400

/ 975-1976196-9719 Year Average £20Nra 0 -- 19 Year Average

4 200- Normal / - -Nr

0 NovNv Dec Jon Feb Mar, Ap 0" DecFa Mo: :;1975 1976 A1976 1977

Figure A 17b Figure A 18a

cxo I i I 1000 (D Freeze-Over at Grand Isle Ferry Dock

0 (D Freeze-Over at Grand Isle Ferry Dock G I) Lake Freez-Deeroo 800 2 Lake Freeze-Over U S W C Water Temp.

() 1C Water Temp . *-® 2C Waler Temp.a ' W C Watr TN,-po I.j2*C waler Temp 0 1)4Cae Tem-----

600 - )4C Water Temp. t "00

2 400 400K " ,

o'/ - 1976-1977 / - - 1977-1978

.- 200 -/ - 19 Year Average - - 19 Year AverageS 200 A ,/"-...Nra 200 ... Normal

0pr 0 No o o eLNov Dec Jan Feb iMar ArNv Dc on Fb Mar Apr

1976 1977 1977 1978

Figure A18b Figure A I 9a

1000 iGrand Isle

- (0 Freeze-Over at Grand lele Ferry Dock

o800 -Z) Lake Freeze-Over

( I C Water Temp.

S @ 2*C Water Temp. ---------

" 600 C)41C Water Temp .- s

F4004E9781977-1978

S 2 0 0 __ - -. ... N o r m alo

-Nov Doc Jan Feb Mor Apr 21977 1978_

Figure A 19b

20

APPENDIX B SUMMARY

Average date 40C (.390 F), 19 De(ember, 29±7days to close of ferry

Average number of freezing degree-days on 19December: 100, 250 freezing (egree-days toclose.

Average date 20 C (3b0 F): 31 December, 17±6days to close of ferry

Average number of freezing degree-days on 31December 200, 150 freezing degree-days toclose.

Average date 10 C (34 0 F): 9 January, 8±4 days toclose of ferry

Average number of freezing degree-days on 9JInuary. 280, 70 freezing degree-days to close.

Average closing date at Grand Isle: 15 JanuaryAverage number of freezing degree-days on 15

January: 342.

Average date of maximum accumulated freez-ing degree-days: 20 March

Average number of days to opening at GrandIsle: 15±5 days,

Average opening date: 5 April

21

Bates, Roy E.Lake Champlain ice formation and ice free dates and

predictions from meteorological indicators I by Roy E.Bates and Mary-Lynn Brown. Hanover, N.H.: U.S. ColdRegions Research and Engineering Laboratory; Springfield,Va.: available from National Technical Information Service,1979.v. 26 p., illus.; 27 cm. ( CRREL Report 79-26. )Prepared for Directorate of Civil Works.- Office, Chief

of Engineers by Corps of Engineers, U.S. Army Cold RegionsResearch and Engineering Laboratory under CWIS 31361.

Bibliography: p. 16.1. Climate. 2. Forecasting. 3. Ice. 4. Ice breakup.

5. Ice formation. 6. Lakes. I. Mary-Lynn Brown, JointAuthor. II. United States. Army. Corps of Engineers.III. Army Cold Regions Research and Engineering Laboratory,Hanover, N.H. IV. Series: CRREL Report 79-26.

*U.S. GOVERNMENT PRINTING OFFICE: 1979602-S20/323