Evaporation from water surfaces is influencing many environmental science processes. Evaporation from pan data is not available as the most well-known method of determining evaporation in many areas, and therefore, the application of experimental mathematical equations in this field is considered. Most of the data for extracting these equations did not belong to cold regions, and as a result, the accuracy of these equations in cold regions has low reliability. In this study, the equations of Trabert (Meteorol Z 13:261–263, 1896), Kohler (Tech Rep Geol Survey Prof Paper 269:127–148, 1954), Kohler et al. (Evaporation from pans and lakes, US Government Printing Office, Washington, 1955), Papadakis (Soil Sci 93:76, 1961), Ântal (Evapotranspiration from com field. Term paper submitted for Dr. R. F. Dale's Agronomy 537 class. Received from personal communication with Dr. Dale (Dept. of Agronomy, Purdue, 1973), Linacre (Agric Meteorol 18:409–424, 1977), Linacre (Water Int 19:5–14, 1994) in Two default and revised modes (14 equations in total) have been used to determine evaporation in cold regions (Emberger climate classifications). Performance index (PI) as an error metric was used to analyze the efficiency of the equations. Findings show that in the absence of proper datasets for revision, Kohler et al. (Evaporation from pans and lakes, US Government Printing Office, Washington, 1955) and Papadakis (Soil Sci 93:76, 1961) equations are more proper options for determining evaporation in cold regions. The revision process increased the efficiency of all equations, with the slightest improvement for Papadakis (Soil Sci 93:76, 1961) and the most improvement for Trabert (Meteorol Z 13:261–263, 1896). According to the behavior of Papadakis (Soil Sci 93:76, 1961) equation in the revision process and its efficiency in both default and revision modes, it can be considered a firm equation in the cold region. The findings reveal that the revised equations have little efficiency difference. It indicates that in cold regions, the influence of the default parameters of the equations on efficiency is more significant than their mathematical formula of the equation. Also, the revision has led to Trabert (Meteorol Z 13:261–263, 1896) equation with relatively good results due to less relative flexibility than other equations. Therefore, it can be concluded that the essential factor to increase the reliability of the application of experimental mathematical equations in determining evaporation from the pan is the use of revised equations with data from cold regions. In addition, among all the equations studied, the revised Kohler et al. (Evaporation from pans and lakes, US Government Printing Office, Washington, 1955) equation was recognized as the most efficient equation for determining evaporation from the pan in the cold regions studied.
