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Measurement Errors in Field Calibration of in Situ Leaf Psychrometers 1
Author(s) -
Savage M. J.,
Cass A.
Publication year - 1984
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1984.0011183x002400020040x
Subject(s) - hygrometer , calibration , thermocouple , environmental science , remote sensing , field (mathematics) , atmospheric sciences , error analysis , observational error , physics , statistics , meteorology , humidity , mathematics , geology , quantum mechanics , pure mathematics
Development of techniques for in situ field measurement of leaf water potential using thermocouple psychrometers highlight the need for an accurate analysis of the errors associated with such measurements. The major sources of error arise from random calibration errors, the temperature dependence of the calibration relationship, temperature differences between the leaf and the psychrometer sensing junction and the error in reading the psychrometer output voltage. In an analysis of such errors, using insulated field‐calibrated psychrometers, the major source of error was found to be in the calibration relationship, particularly as temperature decreased and approached the value of the calibration intercept. This resulted in total relative error values of 8 to 10% of the measured water potential at 0°C, whereas the error was less than 4% for temperatures greater than 20°C (for a potential of —1250 kPa).