Entomology Departmental Series No. 2 October 1988
Alabama Agricultural Experiment Station Auburn University
Lowell T. Frobish, Director Auburn University, Alabama
A Microcomputer-based
Weather Simnulator of the
Soybean and Peanut
Growing Regions of Alabama
d
A MICROCOMPUTER-BASED WEATHER SIMULATOR FOR
THE SOYBEAN AND PEANUT GROWING REGIONS OF ALABAMA
Z. R. SHEN, T. P. MACK, AND R. R. GETZ'
INTRODUCTION
A microcomputer-based weather simulation model can 
be used
for a "hard" and a "soft" application. A 
hard application means
that the model can be used to control a man-made 
weather
environment, such as a weather chamber or greenhouse 
(2), and a
soft application means the use of a model in 
weather-dependent
management, such as agricultural crop management. Both
applications are increasingly needed in agricultural 
research.
Use of observed weather data provides a solution 
which is based
on only one weather scenario. No weather data 
are available for
some locations, which limits model utility. 
A weather model is
often required for solving these problems so that 
weather-
dependent IPM strategies can be assessed.
1
Respectively, Institute of Integrated Pest Control,
Beijing Agriculture University, Beijing, People's 
Republic of
China; Associate Professor of Entomology; and 
Agricultural
Meteorologist, National Weather Service.
Information contained herein is available to all without regard to race
color, sex, or national origin
Described herein is a stochastic weather model that
generates weather data for the soybean and peanut growing regions
in Alabama. Nine locations were examined in these regions:
Belle Mina, Birmingham, Fairhope, Headland, Huntsville, Marion
Junction, Mobile, Muscle Shoals, and Selma, figure 1.
MODEL DESCRIPTION
The simulation model can generate daily maximum and minimum
temperatures (tmax and tmin), precipitation (p), and solar
radiation (r). Called ALWGEN, it has been developed from WGEN,
which is a weather model for simulating weather in 139 locations
in the United States (6). ALWGEN is written in GWBASIC (1) for
IBM compatible personal computers with a 5.25-inch disk drive.
The model provides daily weather data (tmax, tmin, p, and r) for
an arbitrary n-year period at one of the 11 previously mentioned
locations. ALWGEN keeps the all structural characteristics of
WGEN. Its temperature and solar radiation generation
parameters are evaluated with interpolation from the results by
Richardson and Wright (6). Principles and assumptions used in
ALWGEN are the same as those in WGEN. The model consists of
three sets of algorithms: a first-order Markov chain, a gamma
distribution, and two sets of weakly stationary generating
process equations. The Markov chain determines the occurrence of
rain on any given day. The outcome of this not only determines
whether precipitation should be given a zero value for that day,
but also influences daily maximum and minimum temperatures and
solar radiation. Rainfall amount is generated with a gamma
-2-
distribution according to whether rainfall occurs on that day. A
weakly stationary process (6) is used in simulating daily maximum
and minimum temperatures and solar radiation. The model mimics
seasonal characteristics of actual weather data for the given
locations.
Precipitation: The precipitation component of ALWGEN is a
two-part algorithm which contains the Markov chain and the gamma
distribution. The Markov chain has two parameters: P(W/W) and
P(W/D), denoting transitional probabilities of a wet day followed
by a wet day, and a wet day followed by a dry day, respectively.
A wet day is defined as a day with 0.01 inch of rain. The
probability density function of p is given by:
f(p)=exp(aln+(a-l)lnp-Bpln(e)-n(r(a))), p, a, >0
where f(p) is the probability density function of p, the a and 0
are shape and scale parameters, respectively; F(a) is the gamma
function of a, and e is the base of natural logarithms; exp
and in are notations of exponential and natural logarithmic
functions, respectively. For 0<a<1, f(p) decreases with
increasing p, and this is appropriate rainfall since small
amounts occur more frequently than large amounts.
The four parameters, P(W/W), P(W/D), a, and S, are called
rainfall generation parameters. They are constant for a given
month but vary from month to month. Using 20 years of actual
-3-
weather data, Richardson and Wright (6) estimated the parameters
for 139 locations in the United States. Three were in Alabama:
Birmingham, Mobile, and Montgomery.
A geographical nearest-neighbor technique was employed to
estimate the rainfall generation parameters for other locations
in Alabama, figure 1. The method used the parameters for
Birmingham, Mobile, or Montgomery as a starting point in an
optimal searching technique for the parameters of the locations
nearest to each of these cities.
An assumption is made for locations where no information is
available on the mean number of wet days per month that there
exists an identifiable series of wet and dry days for that
location, and that the series is similar to the city used as the
starting point. This implies that values of P(W/W) and P(W/D)
remain those which were estimated by Richardson and Wright (6).
For example, P(W/W) and P(W/D) have same values for Auburn,
Selma, Marion Junction, and Headland as for Montgomery. Thus,
the estimation of four parameters descends to two-parameter
problem. Only a and need to be estimated.
Estimation of a and B can be done with a method of random
perturbation on the basis of the relationship O=M/a, where M is
the arithmetic mean of daily precipitation for wet days. Grey
target bleaching was used for optimization as described in Shen
and Mack (89) for = and at each of the eight locations other
than Birmingham, Montgomery and Mobile, table 1.
-4-
Fig. 1. Locations in Alabama chosen for weather
simulation by ALWGEN. Stars indicate locations where
parameter estimates were estimated by Richardson and
Wright (6), and dots indicate locations where parameters
were estimated by research reported in this paper.
Dashed lines indicate the nearest-neighbor location used
for the estimation of P(W/W) and P(W/D). AB=Auburn,
BH=Birmingham, BM=Belle Mina, FH=Fairhope, HL=Headland,
HV=Huntsville, MB=Mobile, MG=Montgomery, MJ=Marion
Junction, MS=Muscle Shoals, and SM=Selma.
-5-
Temperature and Solar Radiation: The procedure for
generating daily values of tmax, tmin, and r has been presented
by Richardson (5). They are determined by multiplying the
residuals by a seasonal standard deviation and adding a seasonal
mean using the equation:
t?(j)=m (j)([X1(j)ec (j)+1
where t?(j) is the daily value of tmax (j=l), tmin (j=2),
and r (j=3); X,(j) is the residual; m,(j) is the mean;
and cj(j) is the coefficient of variation for day i.
The X.(j) may be generated with the weakly stationary
generating process (4), described by
X (j)=AX?_.(j)+BE?(j)
where Et(j) is a (3 x 1) matrix of independent random
components that are normally distributed with a mean of zero and
a variance of unity, A and B are (3 X 3) matrices whose elements
are defined such that the new sequences of residuals have the
desired serial correlation and cross-correlation coefficients.
The values of the elements have been calculated by Richardson and
Wright (6) and have not been changed in ALWGEN.
The values of m?(j) and cj(j) change seasonally and
are both dependent on the wet or dry status as determined from
the precipitation component of the model. The change is
described by a finite Fourier series:
-6-
uL=i + C*cos(2w/365*(i-T)),
where u
1 
is the value of the mj(j) or ci(j) on day
i, ii is mean of uj, C is the amplitude of the harmonic, and
T is the position of the harmonic in days. Values of u, C, and T
must be determined for the mean and coefficient of variation of
each weather variable (tmax, tmin, r). The values of T for
temperature (tmax, tmin) are assumed to be 200 days, and for
solar radiation to be 172 days for any location in the United
States. The values of ii and C have been estimated from weather
data and have been plotted in contour maps by Richardson and
Wright (6). The values of ii and C for ALWGEN were obtained by
interpolation in the contour maps, table 2.
The ALWGEN Program: ALWGEN can be used to generate daily
values of precipitation, maximum temperature, minimum
temperature, and solar radiation. The program listing of ALWGEN
is in the appendix, and inputs required for the program are shown
in table 3. A compiled version of the program is available upon
request from the second author.
This program maintains the function of precipitation and
temperature correction of WGEN (6). There will be differences
between simulated and actual weather patterns caused by the
temporal and spatial smoothing that is inherent in the model and
by topographic features inherent to the location. Procedures are
incorporated that correct these differences if actual mean
monthly values are available.
-7-
i=ll eee, 365
The precipitation correction factor for a given month is
calculated as the mean monthly precipitation from actual data
divided by the mean monthly precipitation generated with the
Markov chain and gamma distribution algorithms. The generated
daily precipitation amounts are multiplied by the precipitation
correction factor for the appropriate month to obtain a corrected
precipitation amount.
Temperature correction is based on the actual mean monthly
temperature. Temperature correction is calculated as the
differences between the actual mean monthly temperature for the
location and the mean monthly temperature theoretically generated
using the parameters for the location. The user may choose to
(1) make no corrections, (2) correct both precipitation and
temperature, (3) correct only precipitation, or (4) correct only
temperature. The codes that are required for the various options
are given in the list of inputs in table 3.
The program prints daily values of the four variables, and a
summary of the monthly and annual amounts is printed at the end
of each year. At the end of the n-year run, the mean monthly and
mean annual amount is also printed.
Comparison of ALWGEN weather variables to observed data:
Mean monthly observed values for rainfall amount and maximum and
minimum temperatures at Belle Mina, Headland, and Selma were
compared to values generated by ALWGEN for model validatione
Observed values for weather variables were obtained from the
National Weather Service. The residuals (observed minus
generated values) were tested for normality with a Shapiro-Wilk
-8-
test (7). These analyses evaluated the null hypothesis that the
residuals are normally distributed. A probability level of a0.05
indicates that the residuals are normally distributed, and that a
statistically acceptable model has been used to describe the
data.
RESULTS AND DISCUSSION
The ALWGEN model has been tested for all of the eight
selected locations in the peanut and soybean growing regions of
Alabama. A 30-year sample of weather data was generated for each
location. Several statistics were selected in comparing the
generated weather data with observed data. The following
statistics were compared for each month: mean precipitation
amount, mean daily maximum temperature, and mean daily minimum
temperature, tables 4-6. The null hypothesis that the residuals
were not normally distributed could not be rejected (P >0.05) at
any of the three locations tested. Thus, ALWGEN was a
statistically acceptable description of the rainfall and
temperature data at all three locations.
Richardson and Wright (6) indicated that in most instances,
the differences between observed and WGEN generated temperature
and solar radiation values were due to the actual data not having
a simple sinusoidal shape as assumed in the model. They
suggested that this could be corrected by the use of the actual
weather data as previously described. The correction options
provide generated daily values that compare very closely with the
-9-
monthly means derived from the actual observations. Mean monthly
precipitation and/or temperatures for selected locations are
compiled by the National Climatic Center and are available from a
number of sources.
The usefulness of this model is in its ability to
stochastically simulate weather events in 11 locations in
Alabama. Several variables could be calculated from these
simulated data, such as the mean number of consecutive wet days
per month and the number of days per month with a daily maximum
temperature of Z95*F. These variables could be used to determine
the probability of the occurrence of a specific plant disease or
the probability of a given growth rate of an insect population in
a given month. Probabilistic calculations such as these can be
informative and cannot be done with observed weather data.
Further, ALWGEN could be connected with pest or plant models to
simulate population growth, such as AUSIMM, the Auburn
University Integrated Soybean Management Model (3). This would
allow for realistic plant growth or pest development scenarios to
be simulated.
ACKNOWLEDGMENTS
We thank M. Gaylor and M. Wooten for their review of an earlier
draft of the manuscript.
10-
REFERENCES
(1) AT & T, 1985. Programmer's Guide. AT&T Personal Computer
6300 GWBASIC By Microsoft. Agora Resource, Inc.
(2) Burrage, S. W. 1987. Practical Considerations for
Computer-based Environmental Control of Glasshouses. Pp.
63-71. In J.A. Clark, K. Gregson and R.A. Saffell (Eds.).
Computer Applications in Agricultural Environments.
Butterworths, London.
(3) Herbert, D. A., P. A. Backman, T. P. Mack, R.
Rodriguez-Kabana, and M. Schwartz. 1987.
Microcomputer-based Model Improves Soybean Pest Management.
Ala. Agr. Exp. Sta. Highlights of Agric. Res. 34: 1.
(4) Matalas, N. C. 1967. Mathematical Assessment of Synthetic
Hydrology. Water Resources Res. 3: 937-945.
(5) Richardson, C. W. 1981. Stochastic Simulation of Daily
Precipitation, Temperature, and Solar Radiation. Water
Resources Res. 17: 182-190.
(6) Richardson, C. W. and D. A. Wright. 1984. WGEN: A Model for
Generating Daily Weather Variables. USDA, Agricultural
Research Service, ARS-8, 83 pp.
(7) SAS Institute Inc. 1985. SAS Procedures Guide for Personal
Computers, Version 6 Edition. SAS Institute, Cary, N.C. 373
PP.
(8) Shen, Z. R. and T. P. Mack. 1987. A Method for Optimal
Estimation Parameters of Stochastic Models. (In Chinese, in
press.)
-11-
(9) Shen, Z. R. and T. P. Mack. 1988. Estimation of Rainfall
Generation Parameters in a Weather Simulation Model. Agric.
and Forest Meteorology. (In review.)
-12-
Table 1. Rainfall Generation Paraseters, 11 locations
1
Location Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Iov. Dec.
Auburn P(V/W) 0.447 0.456 0.435 0.380 0.475 0.457 0.436 0.408 0.514 0.444 0.348 0.471
P(/D) 0.269 0.289 0.262 0.219 0.185 0.220 0.317 0.264 0.166 0.117 0.175 0.279
* 0.758 0.691 0.863 0.853 0.718 0.714 0.724 0.771 0.543 0.728 0.820 0.725
P 0.797 0.680 0.944 1.037 0.755 0.635 0.801 0.496 1.179 0.720 0.773 0.788
Belle Nina P(W/I) 0.491 0.505 0.475 0.444 0.530 0.481 0.548 0.426 0,480 0.395 0.457 0.495
P(W/D) 0.264 0.299 0.285 0.245 0.183 0.220 0.307 0.265 0.175 0.144 0.213 0.267
a 0.643 0.669 0.683 0.746 0.687 0.639 0.851 0.670 0.676 0.677 0.797 0.647
1 0.710 0.701 0.943 0.818 0.764 0.645 0.456 0.529 0.744 0.724 0.648 0.769
Birmingham P(N/W) 0.491 0.505 0.475 0.444 0.530 0.481 0.548 0.426 0.480 0.395 0.457 0.495
P(N/D) 0.264 0.299 0.285 0.245 0.183 0.220 0.307 0.265 0.175 0.144 0.213 0.267
* 0.643 0.640 0.648 0.712 0.675 0.626 0.802 0.660 0.676 0.630 0.715 0.647
1 0.710 0.765 0.845 0.724 0.662 0.699 0.499 0.629 0.744 0.716 0.593 0.769
Fairhope P(W/M) 0.419 0.483 0.514 0.340 0.419 0.547 0.593 0.515 0.538 0.444 0.375 0.493
P(W/D) 0.294 0.286 0.257 0.197 0.202 0.280 0.446 0.351 0.232 0.135 0.193 0.271
a 0.577 0.629 0.675 0.515 0.644 0.624 0.713 0.768 0.672 0.675 0.665 0.667
I 0.766 0.816 0.875 1.434 0.902 0.796 0.697 0.626 1.102 0.875 0.828 0.786
- 13-
Headland P(V/W)
Huntsville P(WIN
Marion Jct. P(W/W)
P(M/D)
Mobi le
P (W/D)
0.447
0.269
0.755
0.767
0.491
0.264
0.643
0.710
0.447
0.269
0.760
0.622
00419
0.294
0.577
0*766
06456
0*289
0*697
09749
00505
00299
00640
0.765
06456
0.289
0.737
0L706
0*483
0*286
0.629
00816
0*435
00262
00699
09786
00475
00285
00648
00845
09435
00262
00800
0.784
00514
0.257
06556
0*969
09380
00219
00668
03939
00444
09275
0.712
0.724
0*380
0*219
04690
09927
0.340
0.197
00512
1.434
0*475
00185
0U64
0*885
0*530
0*183
0.773
00684
0.475
00185
0*683
0*716
06419
00202
0.*644
06902
0.457
0*220
0*798
09733
0.481
0*220
0.*626
00699
04457
09220
0*715
0*697
00547
00280
0.623
00799
0*436
0*317
011629
00892
0.548
0.307
00802
00499
0.436
09317
00620
019648
0.593
00446
0L713
09697
0.40
00264
0*863
00631
00426
00265
00729
00454
00408
09264
09838
0*471
0*515
0*351
00686
06774
09514
00166
0*611
10011
00480
0.175
0*676
0*744
0*514
00166
00546
l.179
0.538
0.232
00548
116109
00444
09117
09636
09747
0.395
0614
0M30
0*716
00444
0.117
00601
09767
00444
0.135
00645
00659
0.348
0*175
00686
06811
0U45
0*213
0*747
0*799
0.348
00175
0*755
00647
0*375
0*193
0.613
00628
0*471
09279
08691
0*687
00495
0*267
0.683
09742
0.471
0*279
04691
0*687
09493
0.271
06624
011894
14-
Montgomery P (W/W) 0.447
P (N/D) 0.269
L 0713
S 0.525
Muscle Shoals*P(WIW)
P(W/D)
P (V/D)
O0.491
00264
0.643
0.710
0.447
0.269
0.760
04622
0.456
0.289
0.691
0.680
0.5 05
0.299
0.675
0.663
0.456
0.6289
09737
0L706
0.435
0.262
0.699
0.786
0.475
0.285
0.688
0.435
0.262
0.800
0.784
0.380
0.219
00.63
0.852
0.444
09245
0.755
0.678
0.380
.219
0.690
0*927
0.475
0.185
0.634
0.681
0.530
0.183
0.724
0.475
0.185
0683
0*716
0.220
0.-706
0.589
0.481
0.220
0.626
0.699
0.457
0.220
0.715
0*697
0.436
0.317
0.620
0.648
0.548
OLOU
0.499
0.436
0.317
0.620
0.648
0.408
09264
0.762
0.408
0.426
0.265
0.707
0.481
0.408
0.264
0.8 38
09471
0.514
04166
0.546
1.179
0.480
0.175
0.676
0.744
0.514
0.166
0.546
1.179
00444
09117
0.601
0.767
0.395
04144
0.630
09716
0.444
0.117
0.0601
0.767
0.348
0.175
0.684
0.619
0.457
0.213
09762
0.665
0.348
0.175
0.755
0.647
'For Birmingham, Mobile, and Montgomery, the parameters are from Richardson and Wright (6)'.
=15-
Selma
0.471
.279
0.691
0.687
00495
0.267
0.647
0.769
0.471
0.279
0.691
0.687
Table 2. Teaperature and solar radiation generation paraneters, 11 locations,
Location ALA? TIND ATI CVTI ACVTI TIN I AlIT CVTJI ACVT DO AR M
Auburn 32.7 74.5 18.0 0.110 -0.076 72.5 54.0 18.1 0.150 -0.120 455 170 272
Belle Nina 34.75 72.0 20.6 0.130 -0.089 70.5 50.7 19.7 0.193 -0.142 441 192 259
Birminghan 33.1 73.3 19.9 0.120 -0.084 71.7 52.3 18.9 0.175 -0.130 446 183 264
Fairhope 30.5 77.3 15.8 0.096 -0.067 74.7 57.9 16.3 0.138 -0.093 462 165 283
Headland 31.3 75.8 16.5 0.100 -0.070 74.0 55.8 17.0 0.143 -0.100 460 167 282
Huntsville 34.7 72.0 20.5 0.129 -0.084 71.7 52.3 18.9 0.175 -0.130 442 190 259
Marion Jct . 32.4 75.3 18.1 0.107 -0.076 73.5 55.3 17.9 0.152 -0.109 452 175 271
Mobile 30.7 77.1 16.0 0.098 -0.070 74.8 57.7 16.5 0.145 -0.095 461 167 281
Hoatgomery 32.4 74.9 18.2 0.106 -0.074 73.0 55.0 17.6 0.150 -0.110 455 172 275
Muscle Shoals 34.7 72.0 21.2 0.13 -0.090 70.5 50.8 19.8 0.193 -0.143 440 193 259
Selma 32.4 75.2 18.0 0.11 -0.075 73.5 55.2 17.8 0.151 -0.109 453 174 273
Variable names are identical to those in UGEN.
-16-
Table 3. Important Program Variables and Their 
Description
(Values of the Inputs are Shown in tables 1 
and 2)
Input Variable
no. name Description 
Source
1 ACOM
2 NYRS
ALAT
3 KTCF
KRFC
4 PWW(I)
5 PWD(I)
Up to 80 characters of user User supplied
comments.
Number of years of data to be User supplied
generated.
location latitude, degrees. User supplied
Temperature correction factor code User supplied
0, if no temperature correction
1, if some correction factor for
maximum and minimum temperatures
Rainfall correction factor code User supplied
0, if no precipitation correction
1, if precipitation to be
corrected.
Monthly probability of wet day Program
given wet on previous day.
Monthly probability of wet day Program
given dry on previous day.
-17-
6 ALPHA(I) Monthly 
values of gamma
distribution shape parameter.
7 BETA(I) Monthly values 
of gamma
distribution scale parameter.
8 TXMD Mean of 
tmax (dry)
ATX Amplitude 
of tmax (wet or dry)
CVTX Mean of 
coef. of var. of tmax
(wet or dry).
ACVTX Amplitude 
of coef. of var. of
tmax (wet or dry).
9 TXMW Mean of 
tmax (wet)
L0 TN Mean of 
tmin (wet or dry)
ATN Amplitude 
of tmin (wet or dry)
CVTN Mean of coef. 
var. tmin (wet or dry)
ACVTN Amplitude 
of coef. var. tmin.
(wet or dry).
Ll RMD Mean of 
r (dry)
AR Amplitude of 
r (wet or dry)
L2 RMW Mean 
of r (wet)
L3 TM(I) Monthly 
values of actual mean
temperature ('F).
L4 RM(I) Monthly 
values of actual mean
precipitation amount 
(in.).
1
1
1
1
I
Program
Program
Program
Program
Program
Program
Program
Program
Program
Program
Program
Program
Program
Program
User supplied'
User supplied"
-18-
"Necessary only if 
temperature and/or rainfall 
correction is
requested by the user.
Table 4. Comparison of ALWGEN-generated Weather Variables with National Weather Service
Means, Belle Nia
Jan. Feb. Mar. Apr. Nay June July Aug. Sept. Oct. Nov. Dec. Annual
Precipitatiom
No. of vet days
observed mean
Generated mean
Amount (in.)
observed mean
Generated mean
Te~ratare
Daily maximum 'VF)
observed mean
Generated mean
Daily minimum (F)
observed mean
Generated mean
Solar radiatiom
Mean daily (ly*)
observed mean
Generated mean
9.17 9.57 9.27 8.57 8.57 8.10 12.9 9.37 7.5 7 7.40 9.53 105.
5.21 4.64 6.504.82 4.36 3.38 4.54 3.23 3.71 2.94 4.39 5.37 -
4.66 4.81 6.87 4.22 4.26 3.55 4095 3.56 3.70 2.67 4.14 5.23 52.62
504 55.0 63s2 74.2 81.3 87.9 90.6 90.5 84.6 74*5 62.8 53.8 -
51.0 53.6i 60.6 70.5 8190 88e8 92.0 89v0 82.3 72c5 62.6 54.3 71.5
30.3 32.5 39.7 48.9 56.7 63.9 673 66.
30.4 32.7 39.5 49.6 59.9 67.2 70.1 67.6
60.2 47.3 38.2 32.6
60.8 51.3 41.8 34.0
50m
205.7 246.9 32990 421.0 478.5 511.1 445.5 4303 378.8 308.6 225.2190.7 347A6
'Missing data.
- 9
Variable
VIV~~ ~~ ~DYU YYII VYI~ ~ ~ VI Y
Table 5. Comparison of ALMGE-generated Weather Variables with lational leather Service Means,
Headland
Variable Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual
Frecipitatioa
No. of vet days
Observed mean -- -
Generated mean 9.77 8.63 9.07 7.57 6.93 8.93 10.4 9.77 7.23 5.03 5.80 9.87 99.0
Amount (in.)
Observed mean 5.27 4.96 5.44 4.58 4.35 4.62 5.95 4.96 4.08 2.33 3.23 4.88 --
Generated mean 6.04 4.84 5.33 4.13 3.87 4.90 5.86 5.33 4.20 2.25 3.15 5.04 54.9
Temperature
Daily maximum ('F)
Observed mean 58.8 62.3 69.7 78.8 84.8 89.9 90.9 90.5 87.1 78.6 68.8 61.6
Generated mean 58,6 59.9 65.1 73.3 81.1 87.7 90.1 88.2 82.7 74.0 66.3 60.3 74.0
Daily ainimum ('F)
Observed mean 37.0 39.3 46.0 54.5 61.8 67.6 70.0 69.6 66.0 54.0 44.4 38.6 --
Generated mean 39.5 41.0 46.4 55.1 63.3 70.0 72.5 70.6 64.7 56.3 47.5 41.4 55.7
Solar radiation
Mean daily (ly.)
Observed mean -- -- ------------ 
----------
Generated mean 235.1 275.8 343.8 439.1 493.7 499.6 457.2 431.2 398.1 339.2 274.1 217.9 367.1
1
Missing data.
-20-
Table 6. Comparison of IAIIGUgenerated Weather Variables vith National Weather Service
Means, Selma
Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual
Precipitation
Io. of vet days
Observed mean
Generated iean 9.13
Amount (in.)
Observed mean 4.87
Generated mean 4.72
Teserature
Daily maximum (*F
observed mean 58.3
Generated mean 57.6
Daily miinum (*F)
observed mean 37.8
Generated mean 37.2
Solar radiation
Mean daily (ly.)
observed mean --
Generated mean 225.9
9.20 11.0 7.27 8.18 8.50 10.6 9.43 6.43 5.00 6.3 10.4 101.2
4.84 6.90 5.05 4.01 4.0O 4.61 3.47 4.15 2.81 3.13 5.47 --
4.91 5.98 4.68 4.3 4.38 4.28 3.03 4*24 2.50 3.09 5.27 51.11
62.7 70.2 78.9 85.5 91.1 92o8 92A6 88.2 79.0 68.1 61.1
59.9 64.7 74.0 82.7 90.0 92.4 90.3 84.4 75.8 65.7 58.7 74.7
40.2 46.8 54.1 61A 68.4 71.4 70.8 66.0 53.6 44.0 39.4 --
39.8 45.5 54.3 63.0 70.172s8 706 64.4 55.8 46.5 39.5 55.0
269.7 339.7 434.6 484.2 50599 458.6 436o9 389.2 329e9 258o5 210.1 362oQ
'Kissing data.
-21-
variable
-22-
APPENDIX
Program lisiting for ALWGEN
-23-
-24-
5 KEY OFF
10 REM Stochastic Alabama Weather Simulator
15 REM Written by Z. R. Shen, People's Republic of China
17 REM Version 1.0, June 7, 1988
20 WIDTH "1lptl:",137
30 LPRINT CHRS(27);CHR$S(15)
32 COLOR 7,1,1
33 CLS:COLOR 4,7,1
34 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1
36 LOCATE 10,1:PRINT" This program simulates daily weather at one of 11
locations within the peanut and soybean growing regions of Alabama. It can be
used for stochastic"
37 PRINT"simulation modeling and for estimation of pest growth/development 
rates
in"
38 PRINT"normal years. The program requires a printer. Please verify that the
printer is ready."
39 LOCATE 20,20:PRINT" Press any key to continue":A$=INKEY$:IF A$="" THEN 
GOTO
39
45 V=TIMER
50 RANDOMIZE (V)
1000 DIM TXM(366),TXS(366),TXMl(366),TXSI1(366),TNM(366),TNS(366),RMO0(366),
RSO(366),RM1 (366),RS1 (366),RC(366),RAIN(366),TMAX(366),TMIN(366),RAD(366)
1010 DIM ACOM$(20)
1020 DIM NI(12),SR(12),SSTX(12),SSTN(12),SSRAD(12),SRAIN(12),STMAX(12),
STMIN(12), SRAD(12),NII(12)
1030 DIM PWW(12),PWD(12),ALPHA(12),BETA(12)
1040 DIM TM(12),PW(12),TG(12),RM(12),RG(12),RCF(12),TCF(12),NWET(12),XNW(12)
-25-
1050 DIM TAMAX(12),TAMIN(12)
1060 DIM TTMAX(12),TTMIN(12),TCFMAX(12),TCFMIN(12)
1070 DIM A(3,3),B(3,3),XIM1(3),E(3),R(3),X(3),RR(3)
1080 FOR I=1 TO 12:READ NI(I):NEXT I
1090 FOR J=1 TO 12:READ NII(J):NEXT J
1100 LLC=1:CLS:COLOR 4,7,1
1105 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
1110 INPUT "Enter the number of years data to be simulated:";NYRS
1111 IF NYRS<1 OR NYRS>10O THEN GOTO 1100
1112 CLS:COLOR 4,7,1
1115 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
1120 KGEN=1
1121 IF KGEN <>1 AND KGEN <>2 THEN GOTO 1112
1122 CLS:COLOR 4,7,1
1124 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
1130 PRINT "KTCF=0: No temp. correction will be made;
1150 PRINT "KTCF=1: Max. and min. temp corrected based on observed mean monthly
temp."
1152 INPUT "Please enter a value for KTCF";KTCF
1153 IF KTCF<>O AND KTCF<>1 THEN GOTO 1122
1155 CLS:COLOR 4,7,1
1157 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
1158 PRINT "KRCF=0: No correction will be made to simulated rainfall data."
1160 PRINT "KRCF=1: Rain will be corrected based on observed mean monthly rain"
1165 INPUT "Please enter a value for KRCF-";KRCF
1170 IF KRCF<>1 AND KRCF<>0 THEN GOTO [155
1180 PRINT :PRINT
-26-
1190 FOR II1 TO 3
1200 FOR J=1 TO 3
1210 READ A(I,J)
1220 NEXT J,I
1230 FOR I-1 TO 3
1240 FOR Ju1 TO 3
1250 READ B(I,J)
1260 NEXT J,I
1290 LC=O
1300 LC=LC+1: IF LC>LLC GOTO 7000
1305 CLS:COLOR 4,7,1
1306 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
1310 LOCATE 5,5:PRINT"Please select one location for simulation of 365 days of
daily weather"
1315 LOCATE 9,10:PRINT"1. Auburn"
1320 LOCATE 10,10:PRINT"2. Belle Mina"
1321 LOCATE 11,10:PRINT"3. Birmingham"
1322 LOCATE 12,10:PRINT"4. Fairhope"
1323 LOCATE 13,10:PRINT"5. Headland"
1324 LOCATE 14,10:PRINT"6. Huntsville"
1325 LOCATE 15,10:PRINT"7. Marion Junction"
1326 LOCATE 16,10:PRINT"8. Mobile"
1327 LOCATE 17,10:PRINT"9. Montgomery"
1328 LOCATE 18,10:PRINT"10. Muscle Shoals"
1329 LOCATE 19,10:PRINT"11. Selma"
1330 LOCATE 21,1O:COLOR 14,1,1:PRINT"Enter a number and press ENTER";:COLOR
7,1, 1
-27-
1332 INPUT ANS
1334 IF ANS <1 OR ANS>12 
THEN GOTO 1330
1336 IF ANS=1 THEN NAMS$="AUBURN"
1337 IF ANS=2 THEN NAM$="BELLE 
MINA"
1338 IF ANS=3 THEN NAM$="BIRMINGHAM"
1339 IF ANS=4 THEN NAM$="FAIRHOPE"
1340 IF ANS=5 THEN NAM$="HEADLAND"
1341 IF ANS=6 THEN NAM$="HUNTSVILLE"
1342 IF ANS=7 THEN NAM$="MARION 
JUNCTION"
1343 IF ANS=8 THEN NAM$="MOBILE"
1344 IF ANS=9 THEN NAM$="MONTGOMERY"
1345 IF ANS=10 THEN NAMS="MUSCLE 
SHOALS"
1346 IF ANS=11 THEN 
NAM$="SELA"
1347 READ NAMELOC$
1348 IF NAMS <> NAMELOCS 
GOTO 1340
1360 READ ALAT
1380 READ TXMD,ATX,CVTX,ACVTX
1400 READ TXMW
1420 READ TMN,ATMN,CVTN,ACVTN
1440 READ RMD,AR
1460 READ RMW
1700 LPRINT "* NAME 
OF LOCATION STUDIED: 
";NAMELOC$
1710 LPRINT "* ALATWSTATION 
LATITUDE: ";ALAT:LPRINT
1720 LPRINT "MAXIMUM TEN?:" 
;TAB( 20) "TXMD="TXMD;TAB( 32) "ATX="ATX;
TAB( 44) "CVTX-"CVTX; 
TAB (56) "AC VTX="AC VTX; 
TAB (68) "TXMW-"TXMW
1730 LPRINT"MINIMUM TEMP :"TAB 
(20) "TMN="TMN ;TAB (32) "ATMN="AThN;
TAB (44) "C VTN="CVTN 
;TAB (56) "AC VTN="AC VTN
-28-
1740 LPRINT"SOLAR RADIATION: "TAB( 20) "RMD-"RMD; TAB (32 )"AR="AR; TAB(44)"RMW-"RMW
2090 REM calculate maximum solar radiation for each day
2100 XLAT=ALAT6.2832/360
2105 CLS
2200 FOR I
=
i TO 366
2210 XI=I:LOCATE 10,20:PRINT "Loop number three: Day=";I
2220 SD=.4102*SIN( .0172*(XI-80.25))
2230 CH=-TAN(XLAT)*TAN(SD)
2240 IF CH>1 THEN H=O: GOTO 2270
2250 IF CH<-1 THEN H=3.1416: GOTO 2270
2260 H=1.570796-ATN(CH/SQR( -CH*CH))
2270 DD=1+.0335*SIN( .0172*(XI+88.2))
2280 RC(I)=889.2305*DD*((H*SIN(XLAT)*SIN(SD))+(COS(XLAT)*COS(SD)*SIN(H)))
2290 RC(I)=RC(I)*.8
2300 NEXT I
2400 FOR I
=
i TO 12
2410 TTMAX(I ) =0:TTMIN(I)=0:RM(I)=0
2420 NEXT I
2500 IF KGEN=2 THEN 2569
2510 REM following rainfall parameters are:
2512 REM PW(I) -- 12 monthly values of P(W/W), probability of given wet
2514 REM PWD(I) - 12 monthly values of P(W/D), probability of given dry
2516 REM ALPHA(I) -- 12 monthly values of shape parameter of gama distribution
2518 REM BETA(I) -- 12 monthly values of scale parameter of gamma distribution
2520 FOR I
=
i TO 12
2522 READ PWW(I)
2524 NEXT I
-29-
2528 FOR I=1 TO 12
2530 READ PWD(I)
2532 NEXT I
2534 FOR I=1 TO 12
2536 READ ALPHA(I)
2538 NEXT I
2540 FOR I=1 TO 12
2542 READ BETA(I)
2544 NEXT I
2569 CVRD=.24:ACVRD=-.08:CVRW=.48:ACVRW=-.13
2570 D1=TXMD-TXMW: D2=RMD-RMW
2580 IF KTCF=O GOTO 2800
2602 PRINT "You have selected that you will supply monthly temperature datato
the program. The data should be in the following format: XX.X XX.X (degrees
F). Supply 12 temperature estimates.";
2603 PRINT "Enter one line for each year that you wish to simulate.":PRINT:PRINT
2604 PRINT " Please enter the file name and drive designation for the
temperature data. For example, A:Weath.dta";
2605 INPUT FILNAM3$
2606 OPEN FILNAM3$ FOR INPUT AS #3
2607 FOR I=1 TO 12
2610 INPUT#3,TM(I)
2620 NEXT I
2630 GOTO 2800
2652 FOR I-1 TO NYRS
2653 INPUT#2,TTMAX(1),TTMAX(2),TTMAX(3),TTMAX(4),TTMAX(5),
TTMAX(6) ,TTMAX(7) ,TTMAX(8) ,TTMAX(9) ,TTMAX(10) ,TTMAX(11) ,TTMAX(12)
-30-
2655 INPUT#2,TTMIN(1),TTMIN(2),TTMIN(3),TTMIN(4),TTMIN(5),
TTMIN(6),TTMIN(7),TTMIN(8) ,TTMIN(9) ,TTMIN(10),TTMIN(11),TTMIN(12)
2657 NEXT I
2800 IF KRCF=O GOTO 2840
2802 CLS:COLOR 4,7,1
2804 PRINT TAB(22) "ALWGEN Weather Simulator" TAB(160):COLOR 7,1,1:LOCATE 5,1
2806 PRINT "You have selected that you will supply monthly rainfall to the
program. The data should be in the following format: XX.X XX.X (inches).
Supply 12 rainfall estimates.";
2807 PRINT "Enter one line for each year that you wish to simulate.":PRINT:PRINT
2808 PRINT " Please enter the file name and drive designation for the rainfall
data. For example, A:Weath.dta";
2810 INPUT FILNAM3$
2812 OPEN FILNAM3$ FOR INPUT AS #3
2815 FOR IJ=1 TO NYRS
2820 INPUT#3,RM(1),RM(2),RM(3),RM(4),RM(5),RM(6),RM(7),RM(8),
RM(9) ,RM(10),RM(11),RM(12)
2830 NEXT IJ
2840 FOR I=1 TO 12
2850 RCF(I)=1
2860 NEXT I
2870 LPRINT:LPRINT
2910 LPRINT
2920 LPRINT
"No." ;TAB( 5)"Day" ;TAB( 10 )"Yr." ;TAB( 15 )"Date" ;TAB( 25 )"Rain" ;TAB(40 )"Max.
Temp.";TAB(55)"Min. Temp.";TAB(70)"Sol. Rad.":LPRINT
2930 LPRINT
-31-
2940 ' FOR IK=i TO 9
2950 PRINT ACOM(IK);
2970 PRINT TAB(23)"P(W/W) "
3000 ' FOR I-i TO 12
3010' PRINT USING "#.### ";PWW(I);
3020 ' NEXT I
3030 ' PRINT TAB(23)"P(W/D) ";
3040 ' FOR J=1 TO 12
3050 ' PRINT USING "#.### ";PWD(J);
3060 ' NEXT J
3070 ' PRINT TAB(23)"ALPHA ";
3080 ' FOR K=1 TO 12
3090 ' PRINT USING "#.### ";ALPHA(K);
3100 ' NEXT K
3110 ' PRINT TAB(23)"BETA ";
3120 ' FOR I1 TO 12
3130 ' PRINT USING "#.### ";BETA(I);
3140 ' NEXT I
3170 ' PRINT
3180 ' NEXT IK
3200 ' PRINT "MAXIMUM TEMP:" 
;TAB(20)"TXMD="TXMD;TAB(32)"ATX="ATX;
TAB (44) "CVTX="CVTX; TAB (56) 
"ACVTX="ACVTX;TAB (68)1"TXMW="TXMW
3210 ' PRINT"MINIMUM TEMP:"TAB(20)"TMN="TMN;TAB(32)"ATMN="AThN;
TAB( 44) "CVTN="CVTN ;TAB( 56) "AC VTN-"AC 
VTN
3220 ' PRINT"SOLAR RADIATION: 
"TAB (20) "RMD-"RHD; TAB (32) "AR="AR 
;TAB (44) "RMW="RMW
3299 CLS
3300 FOR J-i TO 366
-32-
3305 LO)CATE 10,20:PRINT "Loop number two: Day="l;J
3310 XJ=J:&DTmC0S(.0172*(XJ-2OO)):DR=COS(.O172*(XJ-172))
3320 TXH( J) =TXMD+ATX*DT
3330 XCR1mC VTX+AC VTX*DT
3340 IF XCR1<O THEN XCR1=.06
3350 TXS(J)uTXM(J)*XCR1
3360 TXH1(J)-TXH(J)-D1
3370 TXS1(J)=TXM1(J)*XCR1
3380 TNM(J)=ThN+ATMN*DT
3390 XCR2=CVTN+ACVTN*DT
3400 IF XCBL2<0 THEN XCR2=,.06
3410 TN(J)=TNM(J)*XCR2
3420 py.(J)=RMJ+AR*DR
3430 XCR3=CVRD+ACVRD*DRt
3450 IF XCR3<0 THEN XCR3=.06
3460 RSO(J)=RNO(J)*XCR3
3470 BM1(J)=BHO(J)-D2
3480 XCR4=CVRW+ACVRW*DR
3500 IF XCR4<0 THEN XCR4=.06
3530 RS1(J)=RM1(J)*XCR4
3550- NEXT J
3600 FOR 114=1 TO 12
- 33-
IF IN
NF=NI
GOTO
NF-1
=1 GOTO 3680
(114-1)+
3700
3650
3660
3670
3680
3700
3800
3810
3820
3830
3840
3850
3 900
3910
3920
3930
3940
3950
3960
3970
3980
3990
4000
- 34-
ZN=NL-NF+ I
FOR J-NF TO NL
S1-S1+TXM(J) /ZN
S2=S2+TXM1 (J) /ZN
53=S3"TNM(J) /ZN
NEXT
IF KGEN-2 GOTO 3950
CALCULATE MONTHLY RAINFALL 
CORRECTION FACTOR
RG( IM)'ALPHA( IH)*BETA( 
IM)*ZN*PW( IN)
IF KRCF-0 GOTO 3940
RCF(IM)'RM( IN)/RG(IM)
IF KTCF-O GOTO 4080
CALCULATE MONTHLY TEMP CORRECTION 
FACTOR
IF KTCF=2 GOTO 4010
TND=(S1+S3)/2:*TMW=(S2+S3 )/2
TG(IM)=TMW*PW(IN)+TND*(1-PW(IM))
TCFMAX(IM)=TN(IM)-TG(IM) 
:TCFMIN(IM)=TCFMAX( IN)
GOTO 4080
TAMAX(IM)=S2*PW(IM)+Sl*(1-PW(IM)):OTAMIN(IM)=S3
IF KTCF=O GOTO 4080.
TCFMAX( IM)-TThAX( IM)-TAMAX( 
IN)
TCFMIN(IM)=TTMIN(IM)-TAHIN(IM)
4100
4140
4150
4160
4170
4180
4200
4210
4220
4230
4250
4260
4270
4280
4300
4310
4330
4340
4350
4360
4380
4390
LPRINT"EST MEAN RAIN
FOR J=1 TO 12
LPRINT USING "#,#4,
NEXT J
LPRINT"RAIN CF
FOR Kmi TO 12
LPRINT USING
NEXT K
IF KTCF=0 GOTO 4800
IF KTCF=2 GOTO 4430
LPRINT"ACT MEAN TEMP
FOR 1=1 TO 12
LPRINT USING "#,###
NEXT I
LPRINT"EST MEAN TEMP
FOR J=1 TO 12
@1 *
"t;RCF(K);
r ~9E 0
to 0
,T (I
LPRINT USING "#o### ';TG(J);
NEXT J
GOTO 4630
LPRINT"ACT MEAN ThAX
FOR I-i TO 12
-35-
IF KRCF-0 GOTO 4300
LPRINT"ACT MEAN RAIN
FOR I=1 TO 12
LPRINT USING "#o### ";RM(I);
NEXT I
IF KGEN=2 GOTO 4300
## it;RG(J);
4450
4460
4480
4490
4500
4510
4530
4540
4550
4560
4580
4590
4600
4610
4630
4640
4650
4660
4670
4680
4690
4700
LPRINT USING "#*#Ii
NEXT I
LPRINT"ACT MEAN THIN
FOR J-1 TO 12
LPRINT USING "#.~li
NEXT J
LPRINT"EST MEAN THAX
FOR I-i TO 12
LPRINT USING "#.#4,
NEXT I
LPRINT'EST MEAN THIN
FOR J-1 TO 12
LPRINT USING "#.#4,
NEXT J
LPRINT'CF. MEAN THAX
FOR I-i TO 12
LPRINT USING "#,,#4
NEXT I
LPRINT"CF. MEAN THIN
FOR J=1 TO 12
LPRINT USING "#,,#i
iN# "TAMIN (J);
#A# ";TCFMAX(I);
*9 9
,# ";TCFMIN(J);
NEXT 3
KYR-NYRS
SYTX=O : SYTN=0 :SYRAD=0 :SYR=0 :SYNW=0
FOR II-1 TO NYRS
IYR-II
IF KGEN=1 GOTO 5060
-36-
I, "
## lf;TTMAX(I);
5030 KK=O:1J1l
5050 IF KK=1 GOTO 5110
5060 IDAYS=365
5070 FLG=IYR MOD 4
5080 IF FLG=O THEN IDAYS=366
5090 KK=1
5100 IF KGEN=1 GOTO 5150
5110 IJ=IJ+1
5150 GOSUB 10000
5170 FOR 114=1 TO 12
5180 SRAIN(IM)=O:GSTKAX(IM)=O :STMIN(IM)=O:OSRAD(IM)=O :NWET(IM)=0
5190 NEXT IM
5200 IM-i :YThAX-O :YThIN=O :YRAD=O :RYR=O :NYWET=O :IDA=0
5300 FOR J=1 TO IDAYS
5310 IDA=-IDA+1
5320 IF IDAYS=366 GOTO 5380
5330 IF J>NI(IM) GOTO 5350
5340 GOTO 5410
5350 114=14+1
5360 IDA=1
5370 GOTO 5410
5380 IF J>NII(IH) GOTO 5350
-37-
5530 SRAIN(IM)=SRAIN(IM)+RAIN(J)
5540 SThAX(IM)=SThAX(IM)+ThAX(J)
5550 STHIN(IM)-STHIN(IM)+TMIN(J)
5560 SRAD(IM)=SRAD(IM)+RAD(J)
5570 RYR=RYR+RAIN(J)
5590 NEXT J
5600 XNM1=O
5610 FOR IM=1 TO 12
5620 XXN-NI(IM)
5630 XNI-=0cN-XNM1
5640 XNMI1-XN
5650 ANW-NWET( IM)
5660 XN( IN) =XNW( IN)+ANW/XYR
5670 SR(IN)-SR(IM)+SRAIN(IN)/XYR
5680 SThAX(IN)=SThAX(IM)/XNI
5690 SSTX(IM)=SSTX(IM)+SThAX(IN)/XYR
5700 SThIN(IM)=STMIN(IM)/XNI
5710 SSTN(IM)=SSTN(IM)+SThIN(IM)/XYR
5720 SRAD(IM)=SRAD(IN)/XNI
5730 SSRAD(IM)=SSRAD(IM)+SRAD(IM)/XYR
5740 YTMAX=YTNAX+STNAX(IM)/12
5750 YTNIN=YThIN+STMIN(IM) /12
-38-
5830 SYR=SYR+RYR/XYR
5840 XYNW=NYWET
5850 SYNW-SYNW+XYNW/XYR
5855 LPRINT:OLPRINT
5860 LPRINT"SUNMARY FOR YEAR ";IYR
5900 LPRINT"NONTH';TAB(16)"JAN";TAB(23)"FEB";TAB(30)"MAR";t
TAB(37)"APR" ;TAB(44)"MAY" ;TAB(51 )"JUNE" ;TAB(58)"JULY"l;
TAB(65)"AUG";TAB(72) "SEPT";*TAB(79) "OCT"; TAB(86) "NOV"; TAB(93) "DEC"; TAB(100)"lYRll
5910 PRINT"WET DAYS";TAB(15)" H
5920, FOR IM=1 TO 12
5930 PRINT USING "##.## ";NWET(IM);
5940 NEXT IM
5950 PRINT TAB(100)NYWET
6000 PRINT"RAINFALL" ;TAB( 15)" "
6010 FOR 114=1 TO 12
6020 PRINT USING "#.o### "l;SRAIN(IM);
6030 NEXT IM
6040 PRINT TAB(100)RYR
6100 PRINT"AVE MAX TENP1";TAB(15)" ";o
6110 FOR IM=1 TO 12
6120 PRINT USING "### ";STMAX(IM);
6130 NEXT IN
- 39-
6200
6210
6220
6230
6240
6250
6300
6370
6410
6420
6430
6440
6450
6480.
6490
6500
6510
6520
6540
6550
6560
6570
PRINT TAB(100)YTMIN
PRINT"AVE RAD";TAB(15)" "t
FOR 114=1 TO 12
PRINT USING "### ";tSRA
NEXT IN
PRINT TAB(100)YRAD
NEXT II
LPRINT :PRINT
LPRINT "WET DAYS";TAB(15)" 
";s
FOR 1N1l TO 12
LPRINT USING "##.l# "#XNW(1
NEXT IM
LPRINT TAB( 100)SYNW
LPRINT 
"RAINFALL"; 
TAB(15)" 
";1
FOR 114=1 TO 12
LPRINT USING "#.(k## ":;SR(
IN);
IN);
NEXT IM
LPRINT TAB(100)SYR
LPRINT "AVE MAX TEMP";TAB(15)" 
"
FOR 114=1 TO 12
LPRINT USING "#lk.## ";SSTX(IM)4
NEXT IM
LPRINT TAB(100)SYTX
LPRINT "AVE 
MIN TEMP";TAB(15)" 
"it
FOR 114=1 TO 12
LPRINJ
NEXT IM
r' USING "##,## ";SSTN(IM);
-40-
W(IN);
6640 LPRINT TAB(100)SYTN
6650 LPRINT "AVE RAD";TAB(15)" ";
6660 FOR IM=1 TO 12
6670 LPRINT USING "###.# ";SSRAD(IM);
6680 NEXT IM
6690 LPRINT TAB(100)SYRAD
6800 LPRINT :LPRINT
6850 GOTO 1300
7000 END
10000 REM THE FOLLOWING SUBROUTINE GENERATES DAILY WEATHER DATA FOR ONE YEAR
10010 IF KGEN=1 GOTO 10050
10020 GOSUB 13000
10050 FOR I=1 TO 3
10051 XIM1(I)-0
10052 NEXT I
10070 IX=9398039!:IP=0
10100 IM=1:CLS
10110 FOR IDAY=1 TO IDAYS
10120 LOCATE 10,20:PRINT"Loop number one: Day=";IDAY
10150 IF IDAYS=366 GOTO 10190
10160 IF IDAY>NI(IM) THEN IM=IM+1
10170 GOTO 10200
10190 IF IDAY>'NII(IM) THEN IM=IM+1
10200 IF KGEN=2 GOTO 10805
10210 REM DETERMINE WET OR DRY DAY USING MARKOV CHAIN MODEL
10240 RN=RND
10250 IF IP<'0 GOTO 10260 ELSE 10370
10260 IF RN<=PWD(IM) GOTO 
10380 ELSE 10300
10300 IP=O
10330 RAIN(IDAY)=0
10340 GOTO 10870
10370 IF RN<=PWW(IM) 
GOTO 10380 ELSE 10300
10380 IP-1
10400 REM DETERMINE RAINFALL 
AMOUNT FOR WET DAYS USING GAMMA 
DISTRIBUTION
10430 AA=1/ALPHA(IM):AB=1/(1-ALPHA(IM))
10440 TR1=EXP(-18.42/AA):TR2=EXP(-18.42/AB)
10460 SUM=O:SUM2=0
10500 RN1=RND:RN2=RND
10530 IF RN1<=TR1 GOTO 10550 
ELSE 10580
10550 S1=0: GOTO 10600
10580 S1=RN1^AA
10600 IF RN2<=TR2 GOTO 
10620 ELSE 10640
10620 S2=0: GOTO 10670
10640 S2=RN2^AB
10670 S12=S1+S2
10700 IF 512<=1 GOTO 10720 
ELSE 10500
10720 Z=S1/S12
10750 RN3=RND
10760 IF RN3=0 GOTO 10750
10770 RAIN(IDAY)=-Z*LOG(RN3)*BETA(IM)*RCF(IM)
10800 REM RAIN(IDAY) IS GENERARED 
RAINFALL FOR IDAY
10802 GOTO 10820
10805 REM GET OBSERVED RAIN(IDAY)
10810 GOSUB 14000
- 42-
10820 IF RAIN(IDAY)<.01 
GOTO 10830 ELSE 10850
10830 IP-0:GOTO 10870
10850 IP=1
10870 IF IPcl GOTO 10910 ELSE 
10950
10900 REM GENERTE TMAX, THIN, 
AND BAD FOR IDAY
10910 RM=RHO(IDAY) :RS=RSO(IDAY)
10920 TXXH=TXH(IDAY) :TXXS=TXS(IDAY)
10930 GOTO 11000
10950 RM=RM1(IDAT) :RS=RS1(IDAY)
10960 TXXH=TXM1(IDAY) :TXXS=TXS1(IDAY)
11000 FOR K=1 TO 3
11010 AA=O
11040 RN1=RND : RN2=RND
11050 U=SQR(-2*LOG(RN1))*C0S(6.283185*RN2)
11070 IF ABS(U)>2.5 
GOTO 11010
11080 E(K)=U
11090 NEXT K
11100 FOR 1=1 TO 3
11120 R(I)=0:RR(I)=0O
11130 NEXT I
11150 FOR 1=1 TO 3
11160 FOR J-1 TO 3
-43-
11270 XIM1(K)=X(K)
11290 NEXT K
11300 ThAX(IDAY)=X(1)*TXXS+TXXM
11310 TMIN(IDAY)=X(2)*TNS(IDAY)+TNM(IDAY)
11350 IF ThIN(IDAY)>ThAX(IDAY) GOTO 11360 ELSE 11380
11360 TM=ThAX(IDAY) :ThAX(IDAY)=TMIN(IDAY) :TMIN(IDAY)TM
11380 TMAX(IDAY)-TMAX(IDAY)+TCFMAX(IN)
11390 TMIN(IDAY)=ThIN(IDAY)+TCFMIN(IM)
11400 REM ThAX(IDAY) is generated THAX for IDAY
11410 REM TMIN(IDAY) is generated THIN for IDAY
11500 R&D(IDAY)=X(3)*RS+RM
11510 BMIN=.v2*RC(IDAY)
11550 IF RAD(IDAY)<RMIN THEN RAD(IDAY)=BMIN
11560 IF RAD(IDAY)>RC(IDAY) THEN RAD(IDAY)=RC(IDAY)
11570 REM RAD(IDAY) is generated BAD for IDAY
11590 NEXT IDAY
11600 RETURN
12000 REM following subroutine generates a uniform random number on the
interval 0 -- 1
12010 DIM K(4)
12050 K(1)i2510:K(2)=7692:K(3)=2456:K(4)=3765
12070 K(4)=3*K(4)+K(2):K(3)=3*K(3)+K(1)
-44-
12150 YFL=(((K(1)*.001+K(2))*.01+K(3) )*.001+K(4))*.01
12200 RETURN
13000 REM RAIN(IDAY) IS OBSERVED RAINFALL FOR IDAY
13500 RETURN
14000 REM GET R&NIDAY)
14160 RETURN
50000 REM DATA OFALBM SOYBEAN AND PEANUT REGIONS (only rain & 100 YR)
50010 DATA 31,59,90,120,151,181 ,212,243,273,304,334,365:REM for NI(12)
50020 DATA 31 960,9919121,152$182 $213,9244,9274t,30513351366 :REM for NII(12)
50030 DATA .567,.253,-.006,.086,.*504,-.*039,-.002,-.w05,.244
50040 DATA .781,.328,.238,0,.637,-.341,0,0,.873
50100 DATA AUBURN
50110 DATA 32.7,74.5,18,.11,-.*076,72.5,54,18.1, .15,-.12,455,170,272
50120 DATA .447,.456,.435,.380,.475,.457,.436,.408,.514,.444,.348,.471
50130 DATA .269,.289,.262,.219,.185,.220,.317,.264,.166,.117,.175,.279
50140 DATA .758,.691,.712,.681,.648,.0706,.620,.762,.9546,.634,.O679,.691
50150 DATA .546,.680,.809,.884,.703,.589,.652,.408,1.179,.793,.621,.0687
50160 DATA 50.0,o50.0,50.0,50.0,o50.0,50.0,50OO50OO50OO50.0,500,50O
50200 DATA BELLE MINA
50210 DATA 34.75,72,20.6, .13,-.089,70.5,50.7,19.7, .193,-.142,441,192,259
50220 DATA .491,.*505,.*475.444,.*530,.*481,.548,.426,.480,.395,.457,.495
50230 DATA .264.299,.*285,.245,.0183,.220,.307,.*265,.0175,.*144,.213,.267
-45-
50320 DATA .491,.505,.*475,.0444.530,.481,.*548,.O426,.480,.395,.457,.495
50330 DATA .264,.299,.285, .245, .183, .220, .307, .265, .175, .144, ,213,.0267
50340 DATA .643,.640,.648,.712,.675,.626,.802,.660,.0676,.630,.715,.647
50350 DATA .710,.765,.845,.O724,.662,.0699,.0499,.629,.744,.716,.593,.0769
50360 DATA 43.9l,46.9,53.4,63.3,70.5,77.4,79.9,79.2973.9,63.3,52.O,45.3
50400 DATA FAIRHOPE
50410 DATA 30.5,77.3,15.8, .096,-.067,74.7,57916.3, .138,.0 093,462,165,283
50420 DATA .419,.*483,.0514,.4340,.419,.*547,.593,.515,.0538,.0444,.375,.493
50430 DATA .294,.*286,.o257,.197,.202,.280,.0446,0.51,.232,.135,.0193,.271
50440 DATA .577,.634,.556,.512,.644,.*623,.713,.709,.553,.658,.0687,.623
50450 DATA .766,.794,.969,1.434,.902,.799,.697,.776,1.132,.658,.616,.896
50460 DATA 50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0
50500 DATA HEADLAND
50510 DATA 31.3,73.8,16.5, .1,-.07,74,55.8,17, 143,.1,460,167,282
50520 DATA .447,.456,.435,.380,.475,.457,.436,.408,.514,.444,.348,.471
50530 DATA .269, .289, .262, .219, .185, .220 .317, .264, .166, .117,.175, .279
50540 DATA .755,.697,.699,.668,.647,.798,.629,.863,.611,.636,.686,.691
50550 DATA .767,.749,.#786,.939,.885,.733,.892,.631,1.011,.747,.811,.687
50560 DATA 50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0
50600 DATA HUNTSVILLE
50610 DATA 34.7,o72,20.5, .129,-.084,71.7,52.3,18.9,.175,-o13,442,190,259
50620 DATA.4150,4544,5048,5842,4035,5749
-46-
50710 DATA 32.4,75.3,18.1, .107,-.076,73.5,55.3,19.7, .152,-.10O9,452,175,271
50720 DATA .447,.456,.0435,.380,.04751,.457,.436,.408,.514,.444,.348,.0471
50730 DATA .269,.289,.262, .219, .185, .220, .317, .264, .166, .117, .175, .279
50740 DATA .7649,.691,.739,.0638.634,.0714,.620,.767,.552,.616,.701,.691
50750 DATA .546,.680,.837,.858,.681,.587,.648,.401,1.185,.763,.624,.687
50760 DATA 50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0
50800 DATA MOBILE
50810 DATA 30.7,77.1,16, .098,-.07,74.8,57.7,16.5, .145,-..095,461 .167,281
50820 DATA .419,.483,.514,.340,.0419,.547,.0593,.5159,.538,.444,.375,.0493
50830 DATA .294, .286, .257, .197, .202, .280,.446, .351, .232, .135, .193, .271
50840 DATA .577.629,.556,.*512,.644,.623,.713,.686,.548,.645,.0613,.624
50850 DATA .766,.816,.9691.434,.902,.799,.697,.774,1.109,.659,.628,.0894
50860 DATA 51.1,54.0,59.4,67.8,74.3,80.2,81.5,81.5,77.5,-68.9,58.5,52.9
50900 DATA MONTGOMERY
50910 DATA 32.4,74.9,18.2,.106,-.074,73,55,17.6, .15,11,l455,172,275
50920 DATA .447,.456,0.435,.0380,.*475,.457,.436,.*408,.514,.*444,.348,.471
50930 DATA .269,.289,.262,.219,.185,.220,.317,.264,.166,.117,.175,.279
50940 DATA .713,.691,.699,.634,.634,.706,.620,.762,.546,.*601,.*684,.691
50950 DATA .525,.680,.9786.852,.681,.589,.0648,.4081.179,.767,.619,.0687
50960 DATA 47.5,50.5,56.7,65.3,72.5,79.0,81. 1,80.0,75.9,65.7,54.9,48.6
51000 DATA MUSCLE SHOALS
51010 DATA 34.7,72,21.2, 13,-.09,70.5,50.8,19.8, .193,-.143,440,193,259
5102 DAA .41,.05,475,444.53,.48,.58,.46,.80,395,457.49
-47-
51100 DATA SELMA
51110 DATA 32.4,75.2,18,.11,-.075,73.5,55.2,17.8,.151,.109,453,174,273
51120 DATA .447,.456,.435,.380,.0475,.457,.436,.*408,.514,.444,.348,.471
51130 DATA .269, .289, .262, .219, .185, .220, .317, .264, .166, .117, .175, .279
51140 DATA .760, .737, .800, .690, .683, .715, .620, .838, .548, .601,.756, .703
51150 DATA .622, .706, .784, .927, .716, .700, .648, .471,1.083, .767, .647, .802
51160 DATA 50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0,50.0
0048-
7