Standard TMY Data

TMY data sets for 234 U.S. locations, derived from the widely accepted 1952-1975 SOLMET/ERSATZ data base, have been modified at the Solar Energy Laboratory for ease of use with the TRNSYS energy system simulation program. The original TMY files are ASCII text files containing one year of weather data (ranging from solar radiation to precipitation) at one hour time intervals. TRNSYS TMY files, containing only the most widely used information from the original files and corrected for known problems, are available from the Solar Energy Lab. These files are much smaller in size than the original TMY files from which they are derived.

The TMY data was derived from 30 years of measured solar radiation and temperatures for 26 locations (denoted by an * in the list of TMY sites below). The remaining 208 locations provided by USNOAA were generated based on other measured meteorological phenomena and vicinity to genuine data sites using a correlated model. Each TMY file as supplied by USNOAA contains approximately 24 different weather variables. Unfortunately, each TMY file is approximately 1 MB in size and requires some corrections. In order to make these files more accessible to TRNSYS users, the Solar Energy Lab at the University of Wisconsin has created a modified TMY database called TRNSYS TMY. The modified TMY files are only a fraction of the size of the original files, are corrected for known problems, and contain the most widely used information from the original files (refer to Table I). Additionally, these modified files are in a format easily accessible to TRNSYS.

A notable feature of the TMY data is the presence of both direct normal and global horizontal surface radiation data. The direct normal radiation data was generated from the corrected global horizontal data using algorithms developed by the Aerospace Corporation under contract with the Department of Energy. These algorithms are documented in the Aerospace Corp. Report No. ATR-78(7592)-1. The TRNSYS Type 16 Radiation Processor, when used in Mode 7, makes use of both global horizontal and direct normal radiation as inputs. This allows the user to make use of the Aerospace Corp. algorithm for separation of global radiation into beam and diffuse components rather than the correlation built into Modes 1, 2, and 3 of the Radiation Processor.

Users should also note that the data are recorded in increments of solar time rather than standard time and that the first record is for hour 1 rather than hour 0. The TRNSYS radiation processor parameters and SIMULATION card should be set up to accommodate this. See sections 4.1.4 and 2.2.1 of the TRNSYS user's manual.

Cities for which data is available:

coming soon...

References:

TABLE I: MODIFIED TRNSYS TMY DATA FIELDS (FIELDS PRESENT IN TRNSYS TMY FILE)

Notes:

(1) Note that this is not horizontal surface beam radiation.

(2) Wind direction expressed as 0 for wind from north, 9 for east, 18 for south, etc.

TABLE II: NON-STANDARD DATA FIELDS AVAILABLE (FIELDS NOT PRESENT IN TRNSYS TMY FILE)