Century Monthly Weather Data File

The weather data file is an ASCII (text) file containing rows of precipitation and 2-meter temperature data. In the Century version 4, the columns must be in a fixed format. In Century 5, this fixed column format is not required. However, Century 5 does require the row/record organization described below.

Comments at the top of file can be entered by starting each comment line with a # character. For example:

# File: CO-Larimer-Monthly.wth
# Created: 1990 May
# Location: Larimer County, CO
# Source: historical

Missing values in the data file are specified by the value -99.99. Century5 will replace the missing value as follows:

For minimum or maximum monthly temperature, the mean monthly value (TMN2M or TMX2M) from the site parameters will be used.
For a precipitation value, the skewed distribution value will be calculated if possible (if PRCSKW is not zero). Otherwise, the monthly mean precipitation (PRECIP) will be used.

If the weather data file contains weather data for a minimum of a ten year period it can be used to generate precipitation means, standard deviations, and skewness values, minimum temperature means and maximum temperature means. These statistical values can be used to drive the stochastic weather generator in Century. You specify the statistical values in the site parameter set .

Monthly Weather Data File Format

The weather data file name must be no more than 8 characters in length and end with a ".wth" extension. The format of the weather file, compatible with Century versions 4 and 5, is:

A four character name field. Valid entries for this field, shown in the required order, are:
1. prec (precipitation)
2. tmin (2-meter minimum temperature)
3. tmax (2-meter maximum temperature)
Two spaces
A four character year field
12 number fields (one for each month) of the format 7.2 (The field is 7 characters in length. 4 characters precede the decimal point, the decimal point is counted as 1 character, and two characters follow the decimal point. Valid characters that make up the numeric values are 0-9 and the minus sign (-).) Precipitation values are entered in centimeters and temperature values are in degrees Celsius.

Example 1

The following is an example of two weather entries from a monthly weather data file formatted to be compatible for Century 4 as well as version 5:

prec  1915   0.31   2.55   5.07   7.01   8.87   5.13   1.61   8.83   3.55   3.53   0.99   0.92
tmin  1915 -13.50  -8.33  -8.17   0.78   1.67   7.00   9.72   8.33   5.39  -0.28  -6.06  -8.78
tmax  1915   4.44   8.56   4.33  16.33  17.50  21.06  26.83  26.06  22.89  18.89  10.78   8.50
prec  1916   1.57   0.31   0.37   1.68   8.07   2.90   4.27   2.84   1.06   2.64   2.06   3.06
tmin  1916 -16.50  -9.50  -4.89  -2.28   1.56   6.28  10.56   9.89   3.33  -2.44  -9.28 -14.78
tmax  1916  -0.61   8.67  14.22  14.33  20.28  25.44  32.39  27.28  24.56  14.78   8.78   1.56

Example 2

The following is an example of two weather entries from a monthly weather data file which is in a format which is NOT valid with Century 4, but is valid with version 5:

prec  1915
0.31    2.55   5.07   7.01   8.87   5.13   1.61   8.83   3.55   3.53   0.99   0.92
tmin  1915
-13.50  -8.33  -8.17  0.78   1.67   7.00   9.72   8.33   5.39  -0.28   -6.06  -8.78
tmax  1915
4.44    8.56   4.33   16.33  17.50  21.06  26.83  26.06  22.89  18.89  10.78  8.50
prec  1916
1.57    0.31   0.37   1.68   8.07   2.90   4.27   2.84   1.06   2.64   2.06   3.06
tmin  1916
-16.50  -9.50  -4.89  -2.28  1.56   6.28   10.56  9.89   3.33  -2.44   -9.28  -14.78
tmax  1916
-0.61   8.67   14.22  14.33  20.28  25.44  32.39  27.28  24.56  14.78  8.78   1.56

netCDF Monthly Weather File

Monthly weather data in a netCDF file in COARDS format is also acceptable. This format is described in the section Monthly Weather Data in a netCDF File.

Daily Weather Data File Format