SERVICE CANADIEN DES FORETSGOUVERNEMENT DU CANADA

THE CANADIAN FORESTRY SERVICEGOVERNMENT OF CANADA

The Canadian Forestry Service is the principalsource of federal expertise in forestry and has beendesignated as the government's lead agency for for-estry matters. Its general objective is to promote thewise management and use of Canada's forest re-sources for the economic, social and environmentalbenefit of Canadians.

Le Service canadien des forets (SCF) reunit lamajorite des specialistes federaux en foresterie; il aete designe comme I'organisme officiel du gouverne-ment responsable du secteur forestier. Son objectifgeneral est de promouvoir I'amenagement et I'utilisa-tion judicieux des ressources forestieres du Canadapour Ie plus grand bien economique, social et envi-ronnemental des Canadiens.

The following are the main functions of the CFS: Voici les principales fonctions du SCF:

1, Coordination of federal policies for the promotionof better resource management and forest indus-try development.Provision of scientific and technological leader-ship in forestry through research and development.

2.3.4.

Provision and analysis of national and interna-tional statistics and information as a basis forpolicy formulation.Development and certification of codes and stan-dards for wood product performance.

5.

Protection of Canada's forests from foreign pests.

1. Coordonner leg politiques federales afin defavoriser I'amelioration de la gestion des res-sources et I'expansion de I'industrie forestiere.

2. Fournir une orientation scientifique et tech-nologique dans Ie domaine de la foresterie, par larecherche et Ie developpement.3. Fournir et analyser leg statistiques et I'informa-lion nationales et internationales qui serviront aetablir leg politiques.4. Mettre au point et homologuer des codes et desnormes en matiere de rendement des produitsdu bois.

5. Proteger leg forets canadiennes en luttant contreleg ravageurs etrangers.

6. Parrainer I'utilisation eventuelle des ressourcesforestieres pour la production d'energie.

7. Adherer aux objectifs environnementaux du gou-vernement federal.

6.

Fostering the potential use of the forest resourcefor energy.Contributing to the environmental objectives ofthe Government of Canada.

7.

Canadian Forestry Service programs are coordi-nated with those of other forestry agencies through avariety of mechanisms, including the CanadianCouncil of Forestry Ministers, the Forest SectorStrategy Committee, management committees forFederal-Provincial Forestry Development programs,national and regional Research Advisory Commit-tees,

and various technical committees for specificprogram areas.

Les programmes du SCF sont menes de con-cert avec ceux d'autres organismes forestiers parI'entremise de divers mecanismes dont Ie Conseilcanadien des ministres des Forets, Ie Comite de lastrategie forestiere, les comites de gestion des pro-grammes federaux-provinciaux de developpementforestier,

les comites nationaux et regionaux con-sultatifs sur la recherche, de meme que diverscomites techniques axes sur des domaines de pro-grammes specifiques.

The Canadian Forestry Service is comprised ofa headquarters unit, six forestry centres, and twonational institutes. The forestry centres are respon-sive to regional priorities and maintain close liaisonwith the respective provincial government forestrydepartments and other clients. They also participatein,

and frequently lead, national programs. Thenational institutes provide the focus for programs ofnational scope.

Le SCF comprend une administration centrale,six centres de foresterie et deux instituts nationaux.Les centres de foresterie doivent repondre aux impe-ratifs regionaux et entretenir une liaison etroite avecleg ministeres provinciaux des Forets. lis participentegalement a des programmes nationaux dont ilsassument frequemment la direction. Les institutsnationaux sont leg foyers des programmes d'en-vergure nationale.

C.E. Van Wagner and T.L. PickettPetawawa National Forestry Institute

Canadian Forestry ServiceGovernment of CanadaForestry Technical Report 33Ottawa 1985

@Minister of Supply and Services Canada 1985

ISBN 0-662-13906-2Cat. No. Fo64-33/1985E

Additional copies of this publication areavailable at no charge from:

Canadian Forestry ServicePlace Vincent Massey, 3rd FloorOttawa, OntarioK1A 1G5

A microfiche edition of this publicationmay be purchased from:

Micromedia Ltd.158 Pearl StreetToronto, OntarioM5H 1L3

Cette publication est aussi disponible en franl;ais so usIe titre Equations et programme FORTRAN de /'IndiceForet-Meteo de la methode canadienne.

First printing 1985Second printing 1987

CONTENTS

Page

Abstract.

IV

Resume..

. IV

Introduction.

Symbols in the Equations 3

Equations and Procedures. 5

Description of Program. 9

Symbols in the Program

11

Program F-32. 12

Sample of Input. . 16

Sample of Output 17

References .18

III

ABSTRACT

Improved official equations are presented for the 1984 version of the Canadian Forest FireWeather Index System. The most recent mathematical refinements serve to further rationalize theFine Fuel Moisture Code and render it more compatible with other developments in the CanadianForest Fire Danger Rating System. The effect of these changes is so slight that no problems areanticipated in converting from the previous version to this new one. Also given is a FORTRANprogram intended as a standard for processing the equations in their most accurate mathematicalform.

RESUME

Ce rapport presente, en complement au systeme de l'lndice canadien foret-meteo, desequations connues qu'on a retouchees. Ces precisions mathematiques veulent rendre I'indice ducombustible leger plus rationnel et davantage compatible avec les nouveaux developpements queconna!t la Methode canadienne d'evaluation des dangers d'incendie de foret. II s'agit de change-ments mineurs qui ne devraient pas faire probleme advenant qu'une equation de la versionanterieure soit a convertir. Le programme FORTRAN se veut une base pour traiter des equationsdans Ie plus pur langage mathematique.

1\/

INTRODUCTION

The present report is a companion to the fourth edition of the Tables for the Canadian ForestFire Weather Index System (Canadian Forestry Service 1987). The equations on which this newedition is based are presented here. Also included is a computer program incorporating themathematical routines leading to the Fire Weather Index (FWI). It is written in FORTRAN 77 to runon a DEC PDP-11/44. With proper modification it could be handled by many smaller computers.

The report is a replacement of Information Report PS-X-58 (Van Wagner and Pickett 1975'),which listed equations for the 1976 version of the Fire Weather Index (FWI) System. Thedevelopment and structure of the FWI System were described originally by Van Wagner (1974) inCanadian Forestry Service Publication 1333, butthe mathematics in that paper are partly obsolete.Publication 1333 has now been replaced by Forestry Technical Report 35 (Van Wagner 1987).

The 1976 version of the FWI System listed the following mathematical changes from theoriginal 1970 version:

1

2.3.4.

Change in equation giving the equilibrium moisture content (EMC) during a wetting cycle inthe Fine Fuel Moisture Code (FFMC), to eliminate an anomaly at very high relative humidity(RH);Replacement of the original temperature correction in the FFMC with separate temperatureeffects on EMC and drying rate;Increase in the amount of rain discarded in the Drought Code (DC) from 1.524 mm to2.8 mm; .Change in the buildup function, f(D), at Buildup Index (BUI) values over 80, in order to causethe FWI to level off in extreme drought.

Note: Further acronyms and symbols are defined in accompanying lists.

The additional mathematical changes in the present version further rationalize the structure ofthe FFMC. This code has worked adequately, but new developments in the Canadian Forest FireDanger Rating System (CFFDRS), of which the FWI System is a part, create a need for a) realisticconversions from code value to actual fuel moisture, b) a common basis for the standard dailyFFMC and its round-the-clock hourly version (Van Wagner 1977) and, c) ready modification forspecial purposes. Accordingly, the new FFMC incorporates the following alterations:

1, A new moisture scale, the FF-scale, with a higher maximum possible moisture content(250% instead of 101%);

2. A new rain-effect equation that operates on moisture content rather than on code value;

3. An adjusted drying rate that operates on the moisture content as expressed by the newmoisture scale, but results in the same rate of change in code value as before;

4.

A variable wetting rate when the EMC is higher than the initial moisture content, in place ofthe fixed rate used previously, and;

5.

An adjustment of the fine fuel moisture function, f(F), in the Initial Spread Index (IS I), to fit thenew higher moisture conversion scale.

1C.E. Van Wagner is a research scientist, and T.L. Pickett is a computer programmer at the Petawawa National Forestry In-stitute, Chalk River, Ontario KOJ 1JO.

1

These changes have been accomplished with very little difference in the output of the systemof equations. That is, the resulting codes and indexes will be sufficiently similar for daily use of thesystem to continue uninterrupted and for the statistical continuity of annual records to be pre-served.

As before, the computer program is set up for the calculation at one time of an entire season'soutput for one station only. Its primary purpose is to illustrate the programming of the equations inorder to give the purest possible mathematical output, with no artificial constraints or limits otherthan those required by the nature of the equations. It is intended to serve as a standard ofcomparison by which the output of any other program may be tested.

This 1984 version (as well as the previous version) includes the computation of the DailySeverity Rating (DSR), as described by Van Wagner (1970). The DSR is a function of the FWIspecifically designed for averaging, either for any desired period of time at a single location, or asan area average of any number of locations. The FWI itself, on the other hand, is not consideredsuitable for averaging, and should be used as its single daily value only. The DSR averaged over awhole season, for example, would be called the Seasonal Severity Rating (SSR) and could beused for comparing fire weather from year to year, or fire climate from place to place.

2

SYMBOLS IN THE EQUATIONS

All quantities used in the numbered equations are represented in the following list by singleletters, sometimes with subscripts. The symbols are arranged in groups according to their place inthe whole. All moisture contents are percentages based on dry weight. Noon refers to standardtime.

WEATHER

-noon temperature, °C

-noon relative humidity, %

-noon wind speed, km/h

-effective rainfall, FFMC

-effective rainfall, DMC

-effective rainfall, DC

FINE FUEL MOISTURE CODE (FFMC)

-fine fuel moisture content after rain

-fine fuel moisture content after drying-

-fine fuel EMC for drying

-fine fuel EMC for wetting

-intermediate step in, calculation of kd

-log drying rate, FFMC, log1om/day

-intermediate step in calculation of kw

-log wetting rate, log10m/day

-previous day's FFMC

-FFMC

DUFF MOISTURE CODE (DMC)

-duff moisture content after rain

-duff moisture content after drying

-log drying rate in DMC, log1oM/day

-effective day length in DMC, hours

-slope variable in DMC rain effect

-previous day's DMC

-DMC after rain

-DMC

3

.

DROUGHT CODE (DC)

-DC

FIRE BEHAVIOR INDEXES (ISI, BUI, FWI)

f(W) -wind function

f(F) -fine fuel moisture function

SEVERITY RATING

.4

EQUATIONS AND PROCEDURES

FINE FUEL MOISTURE CODE (FFMC)

(1)mo = 147.2 (101 -Fo)/(59.5 + Fo)

= r _ 050 ., ro > 0.5 (2)r f

mr = mo + 42.5 rf (e-100/(251-mo)X1 -e-6.93/r,), mo:5 150 (3a)

mr = mo + 42.5 rf (e-1OO/(251-moI)(1-e-6.93ir')+O.0015 (mo -150)2 rfo.s, mo> 150 (3b)

Ed = 0.942 HO.679 + 11e(H-100)/10 +0.18 (21.1-T)(1-e-O.115H) (4)

Ew = 0.618 HO.753 + 10e (H-100)/10 +0.18 (21.1 -T)(1 -e-O.115H) (5)

= 0.424 [1-(H/100)1.7] +0.0694 Wo.s [1-(H/100)81ko (6a)

~ = ko x 0.581 eO.O365T (6b)

1-(~)1.7] + 0.0694 WO.5[1-(~)8], 100 100

kl = 0.424

(7a)

kw = k1 X 0.581 eO.O365T (7b)

= Ed + (mo -Ed) x 10-~m (8)

= Ew -(Ew -mo) x 10-kwm (9)

F = 59.5 (250-m)/(147.2 + m) (10)

The FFMC is calculated as follows:

1. Previous day's F becomes F o.

2.

Calculate mo from F 0 by Equation 1.

3a. If ro > 0.5, calculate rf by Equation 2.b. Calculate mr from rf and mo by Equation 3a or 3b.

(i) If mo :5 150, use Equation 3a.(ii) If mo > 150, use Equation 3b.

c. Then, mr becomes the new mo'

4. Calculate Ed by Equation 4.

5a, If mo > Ed, calculate kd by Equations 6a and 6b.b. Calculate m by Equation 8.

6.

If mo < Ed, calculate Ew by Equation 5.

7a. If mo < Ew, calculate kw by Equations 7a and 7b.b. Calculate m by Equation 9.

8.

If Ed 2: mo 2: Ew, let m = mo.

9. Calculate F from m by Equation 10. This is today's FFMC.

There are two restrictions in the use of these equations: 1) Equation 3 (a or b) must not be usedwhen ro ~ 0.5 mm; that is, in dry weather the rainfall routine must be omitted. 2) m has an upperlimit of 250; that is, when Equation 3 (a or b) yields mr > 250, let mr = 250.

5

DUFF MOISTURE CODE (DMC)

(11)ro> 1.5= O.92ro -1.27,re

(12)M = 20 + e(5.6348 -PJ43.43)0

(13a)Po .$; 33b = 100/(0.5 + 0.3 Po),

33<Po=565 (13b)= 14 -1.3 In Po'b

Po> 65 (13c)= 6.2 In Po -17.2,b

(14)Mr = Mo + 1000re/(48.77 + bre)

(15)= 244.72 -43.43 In (Mr -20)Pr

= 1.894 (T + 1.1) (100 -H) Lex 10-6 (16)K

(17)p = Po (or Pr) + 100K

The DMC is calculated as follows

Previous day's P becomes Po'1

2a. If ro > 1.5, calculate re by Equation 11.b. Calculate Mo from Po by Equation 12.c. Calculate b by the appropriate one of Equations 13a, 13b, or 13cd. Calculate Mr by Equation 14.e. Convert Mr to P r by Equation 15. P r becomes new Po.

Take Le from Table 1 below.3,

Calculate K by Equation 16.4

Calculate P from Po (or Pr) by Equation 17. This is today's DMC.5

There are three restrictions on the use of the DMC equations: 1) Equations 11 to 15 are notused unless r 0 > 1.5; that is, the rainfall routine must be omitted in dry weather. 2) P r cannottheoretically be less than zero. Negative values resulting from Step 2e above must be raised tozero. 3) Values of T less than -1.1 must not be used in Equation 16. If T < -1.1, let T = -1.1.

Table 1Effective day-lengths (Le) for DMC

DROUGHT CODE (DC)

r> 2.8 (18)= O.83ro -1.27,rd

(19)00 = 800e-DJ400

(20)Or = 00 + 3.937r d

(21 )Dr = 400 In(800/Qr)

(22)v = 0.36 (T + 2.8) + ~

(23)= Do (or Dr) + Q.5VD

6

The DC is calculated as follows:

1. Previous day's 0 becomes Do.

2a. If ro > 2.8, calculate rd by Equation 18.b. Calculate 00 from Do by Equation 19.c. Calculate Or by Equation 20.d. Convert Or to Dr by Equation 21. Dr becomes new Do'

3. Take 4 from Table 2 below.

4. Calculate V by Equation 22.

Calculate D from Do (or Dr) by Equation 23. This is today's DC.

5.

There are four restrictions on the use of the DC equations: 1) Equations 18 to 21 are not usedunless r 0> 2.8; that is, in dry weather the rainfall routine must be omitted. 2) Dr cannot theoreticallybe less than zero. Negative values resulting from Step 2d above must be raised to zero. 3) Valuesof T less than -2.8 must not be used in Equation 22. If T < -2.8, let T = -2.8. 4) V cannot benegative.

If Equation 22 produces a negative result, let V = O.

Table 2Day-length factors (LJ for DC

-1.6 -1.6 -1.6

INITIAL SPREAD INDEX (ISI)

f(W)

= eOO5039W (24)

f(F) = 91.ge-O.1386m[1 +mS.31/(4.93 X 107)] (25)

R = 0.208 f(W) f(F) (26)

BUILDUP INDEX (BUI)

u = 0.8 PO/(P + 0.40), P s 0.40 (27a)

= P -[1 -O.8D/(P + O.4D)][O.92 + (O.O114P)1.7],u P > 0.40 (27b)

FIRE

WEATHER INDEX (FWI)

1(0) = O.626Uo.809 + 2, U:s;80 (28a)

f(O) = 1000/(25 + 108.64 e-O.O23U), U > 80 (28b)

B = 0.1 R 1(0) (29)

InS = 2.72 (0:434 In 8)0-647,

8>1

(30a)

S

= B, B:51 (30b)

7

The ISI, BUI, and FWI are calculated as follows:

1, Calculate f(W) and f(F) by Equations 24 and 25.

2.

Calculate R by Equation 26. This is today's 151.

3.

Calculate U by Equation 27a if P :5 0.40, or by Equation 27b if P > 0.40. This is today'sBUI.

4.

Calculate f(O) by Equation 28a for values of U up to 80. If U > 80, use Equation 28b.

5. Calculate B by Equation 29.

6.

If B > 1, calculate S from its logarithm, given by Equation 30a. If B s 1, letS = B according to Equation 30b. S is today's FWI.

DAILY SEVERITY RATING (DSR)

DSR = 0.0272 (FWI)1.77 (31 )

8

DESCRIPTION OF PROGRAM

The computer program presented here descends from one written by Simard (1970) at theformer Forest Fire Research Institute. That program was designed to process weather data frommany stations for a whole season. There was provision for missing data and for limits to guardagainst abnormal weather data. It was a complex program requiring, at the time, considerablecomputer capacity.

Simard's program was simplified by Engisch and Walker (1971) to handle one season'sverified weather data for one station only, eliminating all unnecessary limits. Kean (1975) subse-quently revised this program, incorporating several newly developed mathematical changes.However, the decision to convert to metric weather measurements rendered his version obsolete.Information Report PS-X-58 (Van Wagner and Pickett 1975) included the metric successor toKean's program. The program listed in this report incorporates the mathematical changesdescribed earlier, but is similar in usage to the one in PS-X-58.

To operate this program, enter first the starting month and the number of days of data in thatmonth. For example, if the starting month is April and the first day is April 13, there will be data for 18days in month 4, and the entry will be 418. Then enter the daily weather observations in order:temperature (OC), relative humidity (%), wind (km/h), and rain (mm). Temperature and rain areentered to the first decimal place; relative humidity and wind are entered in whole numbers. Theoption of entering weather data in Imperial units is provided, but the output converts them to metric.

The standard starting values of the three fuel moisture codes, namely FFMC 85, DMC 6, andDC 15, are incorporated in the program. However, the option of entering any desired starting valuesis also provided.

The output is listed in twelve columns: date (month and day), the four kinds of weather data,the three fuel moisture codes (FFMC, DMC, DC), the three fire behavior indexes (ISI, BUI, FWI),and the Daily Severity Rating (DSR). The computer stops automatically after the last day's weather.The program includes no limits on the input data other than those needed to prevent mathematicalanomalies. All moisture codes are carried from day to day in precise floating-point format, as are allintermediate quantities leading to the daily FWI. The output is thus in the purest possiblemathematical form and constitutes a reference against which calculations from other computerprograms or from the FWI System Tables (Canadian Forestry Service 1984) may be compared.

The main uses of this standard program 1 are for development work on the FWI System, and

for reference purposes as described previously. Operational programs designed for processingdaily weather observations from many stations throughout a fire season will naturally have differentinput and output arrangements.

Two points warrant comment. The first is the degree of precision necessary when printing outthe daily codes and indexes. The standard program rounds all codes and indexes to the nearesttenth, and prints them out to one decimal place. However, whole-number (i.e., integer) output is, nodoubt, adequate for most operational purposes. In certain cases, the first decimal may bedesirable for the FFMC (especially above 90), and for the ISI (especialy below 10). The DSR isgiven to two decimal places, and is best used in that form.

The second comment refers to the precision with which the three moisture codes (FFMC,DMC, and DC) are carried over from day to day. The standard program carries over each day'scode values in full floating-point format, equivalent to about seven significant figures (four or fivedecimal places). However, if computer storage capacity is a limiting factor, something less thanperfect accuracy in output may be acceptable in operational use. Trials were made at threereduced levels of the precision to which the three moisture codes are carried over from day to day:1) two decimals, 2) one decimal, and 3) integers. The results of two seasons' tests, as percentageof error-days in the output of each code and index, are listed in Table 3.

1 Designated Program F-32 (January 28, 1986). Enquiries may be directed to the Petawawa National Forestry Institute,

Canadian Forestry Service, Chalk River, Ontario KOJ 1JO

9

Table 3Percent of days in which whole-number output of the FWI System components is inerror at three levels of precision in the carryover of moisture codes from day to day.Compared with standard floating-point precision.

2-decimalcarryover

1-decimalcarryover

Integer carryover(no decimals)

% of daysin error

by 1

% ofin e

by

% of days in error by

Component 1 2 3 1or more

1.6

8.2 1.4

Conclusions to be drawn from Table 3 are:

1 Carrying over the moisture codes with two decimal places provides nearly perfectaccuracy of output except for occasional one-integer errors in the DC, which are of littleconsequence.

2.

Carrying over one decimal place may be precise enough for some operational use. Forexample, one-integer errors would occur in the DMC on about one day in 25, in theFFMC on about one day in 50, and in the FWI on about one day in 200.

3. Carrying over the moisture codes as integers produces a generally inaccurate output,and is not recommended.

Of all the six components, the DC is the only one to exhibit an anomalous pattern in Table 3.Because the DC has limited power of self-correction in the mathematical sense compared with theFFMC and DMC, it tends to slip out of tune by one digit and to remain so for days on end.Considerably more sampling would be needed to establish its average pattern.

The standard program for the FWI System is listed in the following pages, followed by samplesof input and output.

10

daysrror1

SYMBOLS IN THE PROGRAM

WEATHER

=

relative humidity, o~

-wind, km/h

R,RA -rain, mm

FINE FUEL MOISTURE CODE (FFMC)

-today's final moisture content

-EMC for wetting

-intermediate value of X

-log dryin[or wetting rate

FFM -today's FFMC

DUFF MOISTURE CODE (DMC)

PO -starting or yesterday's DMC

RK -drying factor

EL(J) -effective day-length for month J

-DMC after rain

WM I -initial moisture content

WMR -moisture content after rain

B -function in rain effect

DROUGHT CODE (DC)

FL(J) -day-length factor for month J

-DC after rain

FIRE BEHAVIOR INDEXES (ISI, BUI, FWI)

-ISI

-intermediate form of FWI

11

PROGRAM F-32

PROGRAM NO.: F-32ccccccccccccccccc

STANDARD 1984 VERSION OF CANADIAN FOREST FIRE WEATHER INDEX SYSTEMAS OF 28-JANUARY-1986.

WRITTEN IN FORTRAN 77.

READS

WEATHER DATA IN EITHER ENGLISH OR METRIC UNITS AND PRINTSOUT IN METRIC ONLY.

CODES AND INDEXES OUTPUT ALL TO ONE DECIMAL PLACE.DAILY SEVERITY RATING OUTPUT TO TWO DECIMAL PLACES.

LMON = LENGTH OF MONTHSEL = DMC DAY-LENGTH FACTORSFL = DC DAY-LENGTH FACTORS

DIMENSION LMON(12), EL(12), FL(12),AST(2),TITLE(20)LOGICAL*l DAT(9),YES,YES1,ANS,ANS1LOGICAL *1 INFMT(40)TYPE 55 FORMAT(' INPUT FILENAME: eg: SAMPLE.DAT ' ,$)ACCEPT 10, INFMT10 FORMAT(40A1)INFMT(40)=0OPEN(UNIT=l,NAME=INFMT,TYPE='OLD',READONLY)OPEN(UNIT=2,STATUS='NEW',NAME='F320UT.DAT')DATA LMON /31,28,31,30,31,30,31,31,30,31,30,31/DATA EL /6.5,7.5,9.0,12.8,13.9,13.9,12.4,10.9,9.4,8.0,7.0,

*6.0/DATA FL /-1.6,-1'.6,-1.6, .9,3.8,5.8,6.4,5.0,2.4, .4,-1.6,-1.6/DATA AST /' ','*'/DATA ANS /'Y'/TYPE 15

15 FORMAT(//lX,'ENTER VIA KEYBOARD EITHER 0 OR 1 '/lX' O* IF DATA IS IN METRIC UNITS'/lX' OR 1 IF DATA IS IN* ENGLISH UNITS')READ(5,*) IUNIT

ccc

20 -METRIC FORMAT, 25 -ENGLISH FORMAT

20 FORMAT(F4.1,214,F5.1)25 FORMAT(F4.0,214,F5.2)

ccc

READS

IN STATION & YEAR.

READ(1,30) TITLE30 FORMAT(20A4)

ccc

THIS SECTION ALLOWS FOR INITIAL VALUES OF FFMC, DMC, DC TO BE OPTIONAL

FO=85.0PO=6.0DOT=15.0TYPE 35

35 FORMAT(' FFMC=85.0, DMC=6.0, DC=15.0; DO YOU WISH TO USE THESE* INITIAL STANDARD VALUES? [Y/N] '$)

ACCEPT lO,ANSlIF(ANS1.EQ.ANS) GO TO 55TYPE,40

12

£~

(/,HSO IMJ Ins ISI ¥JO JWO JWJJ ¥

dW3J. 3J.VO ,'X1'///)J.VWHOJ S01(S01'Z)3J.I}iM

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HI=HJ.=XJ. 001

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NIYHONIMHH

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v~va H3H~V3M X~IVa SaV3H

T+sxvaN-(~)NOw~=sxvaI 09S9 O.L o~

T=sxvaI09 O.L o~ (W.a3.~)~I

(~)NOW~=NNZT'w=~ 06Z oa

(II.'T.S~":Ja ','T.S~":Jwa ','T.S~":Jw~~ HO~ S3n~VA ~VI.LINI ,).LVWHO~ SL

.LOa'Od'O~ (SL'Z)3.LIHM(11~vOZ'XTIIITV6'XT).LVWHO~ OL

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(,Zf-~ :.ON WVH~OHd,THT).LVWHO~ S9(S9'Z)3.LIHM

(ZI'TI).LVWHO~ 09sxvaN 'w (09'T)av3H SS

:>:>:>:>

" HoLNOW

~NloLHVoLS NI sxva ~O H38WfiN aNV HV3X 3HoL ~O HoLNOW ~NloLHVoLS SaV3H

J.oo'O'l J.d3:):)V($', :(T.~j) :)0 ,)J.VWHOj OS

OS 3dXJ.Od'O'l J.d3:):)V

($', :(T.~j) :)wo ,)J.VWHOj S~

S~ 3dXJ.OJ'O'l J.d3:):)V

($', :('['~j) :)Wdd ,)J.VWHOd O~

ccc

FINE FUEL MOISTURE CODE

110 WMO=(147.2*(101-FO))/(59.5+FO)IF(R.GT.0.5) GO TO 115GO TO 125

115 RA=R-.5IF(WMO.GT.150.) GO TO 120WMO=WMO+42.5*RA*EXP(-100./(251.-WMO))*(1.-EXP(-6.93/RA))GO TO 125

120 WMO=(WMO+42.5*RA*EXP(-100./(251.-WMO))*(1.-EXP(-6.93/RA)))+*(0.0015*(WMO-150. )**2)*RA**.5

125 IF(WMO.GT.250.) WMO=250.ED=0.942*(H**0.679)+(11.*EXP((H-100.)/10.))+0.18*(21.1-T)

**(1.-1./EXP(0.115*H))IF(WMO-ED) 130,135,140

130 EW=.618*(H**.753)+(10.*EXP((H-100.)/10.))+.18*(21.1-T)**(1.-1./EXP(0.115*H))

IF(WMO.LT.EW) GO TO 145135 WM=WMO

GO TO 150140 Z=0.424*(1.-(H/100.)**1.7)+(0.0694*(W**0.5))*(1.-(H/100.)**8)

x=z*(0.581*(EXP(0.0365*T)))WM=ED+(WMO-ED)/10.**XGO TO 150145 Z=.424*(1.-( (. -.

*/100.)**8)x=z*( .581*(EXP( .0365*T)))WM=EW-(EW-WMO)/10.**X

150 FFM=(59.5*(250.-WM))/(147.2+WM)IF(FFM.GT.101.) GO TO 155 ,,' ,.

IF(FFM) 160,165,165 "."l'c' , ,155 FFM=101. ;"'

A ' I ,~; ,.165 ., ~ '.;. '" ..

GO TO '"r,..'160 FFM=O.O \ !;:;,;~.

., ., ,\

lOO.-H)/100.

)**1.7)+( .O694*(W**.5) )*(1.-«100.-H)

ccc

DUFF MOISTURE CODE

165 IF(T+1.1.GE.0.) GO TO 170T=-l.l

170 RK=1.894*(T+1.1)*(100.-H)*(EL(J)*0.0001)175 IF(R.GT.1.5) GO TO 180

PR=POGO TO 205

180 RA=RRW=0.92*RA-1.27WMI=20.0+280./EXP(0.023*PO)IF(PO.LE.33.) GO TO 185IF(PO-65.) 190,190,195

185 B=100./(0.5+0.3*PO)GO TO 200

190 B=14.-1.3*~.LOG(PO)GO TO 200

195 B=6.2*ALOG(PO)-17.2200 WMR=WMI+(1000.*RW)/(48.77+B*RW)

PR=43.43*(5.6348-ALOG(WMR-20.»205 IF(PR.GE.O.) GO TO 210

PR=O.O210 DMC=PR+RK

14

12

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SAMPLE OF INPUT

FWI TEST DATA APRIL 13 TO MAY 31 418 4 Indicates starting month, In this case April.

17. 42 25 -April 13 18 indicates no. of days in starting month.20. 21 25 2.48.5 40 176.5 25 613. 34 24

6. 40 22 0.45.5 52 68.5 46 169.5 54 207. 93 14 9.0

6.5 71 17 1.06. 59 17

13. 52 415.5 40 1123. 25 919. 46 16 -April 3018. 41 20 -May 1

14.5 51 1614.5 69 1115.5 42 821. 37 823. 32 1623. 32 1427. 33 1228. 17 27

23.5 54 2016. 50 22 12.2

11.5 58 2016. 54 16

21.5 37 914. 61 22 0.215. 30 2720. 23 1114. 95 3 16.420. 53 4 2.8

19.5 30 1625.5 51 20 6.010. 38 2419. 27 1626. 46 11 4.230. 38 22

25.5 67 19 12.612. 53' 2811.821. 38 813. 70 20 3.89. 78 24 1.4

11 .5 4 1 6 ~::~; 15.5 39 9

18\36 ~:~::~ ;Temperature °C Relative Wind km/h Rain mm

Humidity %

16

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561 581 5L1 591 551 5~1 5£1 5'l1 511 501 56 58 5L 59 55 5~ 5£ 5'l 51 5O£ ~6'l ~8'l ~L'l ~9'l ~5'l ~~'l ~£'l ~'l'l ~1'l ~O'l ~61 ~81 ~L1 ~91 ~51 ~~1 ~£1 ~

L~

REFERENCES

Canadian Forestry Service. 1987. Tables for the Canadian Forest Fire Weather Index System.Environ. Can., Can. For. Serv., For. Tech. Rep. 25 (4th ed.). 48 p.

Engisch, R.L.; Walker, J.D. 1971. PDP-8L version of Simard's Fire Weather Index Program.Environ. Can., Can. For. Serv., Petawawa Forest Exp. Sta., Intern. Rep. PS-23. 10 p.

Kean, W.A. 1975. A PDP-8L program for calculating the Fire Weather Index. Environ. Can., Can.For. Serv., Petawawa Forest Exp. Sta., Info Rep. PS-X-57. 12 p.

Simard, A.J. 1970. Computer program to calculate the Canadian Forest Fire Weather Index.Environ. Can., Can. For. Serv., Forest Fire Res. Inst., Intern. Rep. FF-12. 18 p.

Van Wagner, C.E. 1970. Conversion of Williams' severity rating for use with the Fire Weather Index.Environ. Can., Can. For. Serv., Petawawa Forest Exp. Sta., Info Rep. PS-X-21. 5 p.

Van Wagner, C.E. 1974. Structure of the Canadian Forest Fire Weather Index. Environ. Can., Can.For. Serv., Pub. No. 1333. 44 p.

Van Wagner, C.E. 1977. A method of computing fine fuel moisture content throughout the diurnalcycle. Environ. Can., Can. For. Serv., Petawawa Forest Exp. Sta. Info Rep. PS-X-69. 15 p.

Van Wagner, C.E. 1987. Development and structure of the Canadian Forest Fire Weather IndexSystem. Can. For. Serv., For. Tech. Rep. 35. 37 p.

Van Wagner, C.E.; Pickett, T.L.1975. Equations and Fortran IV program for the 1976 metric versionof the Forest Fire Weather Index. Can. For. Serv., Petawawa Forest Exp. Sta., Info Rep. PS-X-58. 20 p.

18