Monthly Average Weather Data

The most commonly available weather data is in the form of monthly averages. The TRNSYS Type 54 Weather Data Generator generates hourly weather data for a typical year given the monthly average values of solar radiation, dry bulb temperature, humidity ratio, and windspeed (optional). WDATA.DAT is a file of monthly average weather data from 329 sites in the United States and Canada. The data is taken from the publication Input Data for Solar Systems by Cinquemani, Owenby, and Baldwin, published by the U.S. National Oceanic and Atmospheric Administration, Asheville, NC.

NREL.DAT is also a file of monthly average weather data from the 239 US sites listed in WDATA.DAT. This file is from the National Solar Radiation Data Base (NSRDB) created by the National Renewable Energy Laboratory (NREL). This file should be more accurate and current than the data in WDATA.DAT. Monthly average weather data in the files WDATA.DAT and NREL.DAT is listed in the following format:

line 1: NLOC

line 2: LOCATION 1 LATITUDE

line 3: I1 I2 I3 ... I12

line 4: w1 w2 w3 ... w12

line 5: TEMP1 TEMP2 TEMP3 ... TEMP12

line 6: LOCATION 2 LATITUDE

line 7: I1 I2 I3 ... I12

ETC...

where:

NLOC: the number of locations in the data base

LOCATION: the name of the location, maximum of 32 characters

LATITUDE: between -90.0 and 90.0 degrees, number must start in column 33

I1-I12: monthly average daily global horizontal solar radiation (kJ/m2)

w1-w12: monthly average humidity ratio multiplied by 104 (kg water / kg air)

TEMP1-TEMP12: monthly average temperature (degrees C)

See section 4.1.10-1 of the TRNSYS Main Manual for more information.