Model from Research Paper INT-293 "Calibration Model for Screen-caged Peltier Thermocouple Psychrometers" by Ray W. Brown and Dale L. Bartos Intermountain Forest and Range Experiment Station, Ogden, UT 84401. The Intermountain Forest and Range Experimental Station is now the Ogden part of the Rocky Mountain Research Station
 

Model Input to Excel Spreadsheet by Michael Burns

This spreadsheet consists of the complete model developed by the US Forest service and published in the free Research Paper INT-293 "Calibration Model for Screen-caged Peltier Thermocouple Psychrometers" by Ray W. Brown and Dale L. Bartos, published in July 1982. This model applies to water potential ranges from 0 to approximately -80 bars, temperatures from 0 to 40 ºC, Peltier cooling times from 15 to 60 seconds, and zero-offsets from -60 to +60 microvolts. The model was developed by the Forest Service to allow calibration corrections to be applied to psychrometer readings taken under non-ideal field conditions. The spreadsheet can handle up to 1000 data points. If you can't figure out how to expand it to handle more, please email me and I'll expand it for you. The upper limit is really determined by your computers resources, rather than by Excel. While the model itself is public domain, this spreadsheet is not. This spreadsheet may be used freely. It is not to be redistributed, sold nor bundled with equipment. If you use it, an acknowledgment or reference in your publications would be nice. We also add the usual warning that we are not responsible for the accuracy of this model, its applicability to your experiment, nor for errors in the model or spreadsheet.

You can download this free Excel spreadsheet in a zipped file named "psycal.zip". The file can be unzipped on a MAC or on a PC. When you unzip psycal.zip, it will produce an Excel file called psycal.xls which will run under Excel 5.0 (or later) on a PC or Mac.

NOTES:

1. If you try to modify the gray areas of the spreadsheet it will claim those areas are protected against modification. What you can do to bypass this is to do a global copy & paste into a new spreadsheet, or if you check the file's properties, the protection password is in the comments section. The protection is just to prevent introducing accidental errors to the algorithm.
2. The psycal.xls Excel file is larger than it needs to be by over a factor of 2 because it was saved in the "Microsoft Excel 97-Excel 2003 & 5.0/95 Workbook" format. If you resave it in the native format for your version of Excel, the file size should be reduced. If you can't open this Excel file using a version of Excel that should be able to open it (Excel 5.0 or later), please contact me with your Excel version and I'll get you a copy that you can use.

You can get a free copy of Research Paper INT-293 "Calibration Model for Screen-caged Peltier Thermocouple Psychrometers" by Ray W. Brown and Dale L. Bartos Intermountain Forest and Range Experiment Station, Ogden, UT 84401 by clicking the link at the top of this page, clicking here, or contacting them at

This research paper contains the model and how it was developed and tested, plus BASIC and FORTRAN source code.

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