Observations of evaporation from U.S. Class “A” pans at six widely scattered sites in Australia have been compared with concur rent observations from Australian standard tanks and estimates by the Prescott, Thornthwaite and Penman methods. In general, Class “A” pan totals are higher than those of tank evaporation and in some months they are more than 25 per cent greater; on 40 per cent of occasions the two instrumental evaporation totals are within 10 per cent. Correlation coefficients between the various evaporation forms are predominantly over 0.9 at all stations except Darwin. However, regression coefficients differ considerably from unity. Estimates by the methods tested are usually less than pan and tank evaporation, at times over 50 per cent less.
C. E. Hounam (Tue,) studied this question.