Comments on “Seasonal Variation in Rain Gage Catch” by J. L. McGuinness and G. W. Vaughan

Abstract

Several types of rain gages were compared in the experimental basin Baye de Montreux (Laboratory for Hydraulic Research, Hydrology, and Glaciology, Federal Institute of Technology, Zurich, Switzerland) near Lake Leman. Ten years of data from the standard gage (Hellmann, 1.5 meters above ground), the ground level gage, the recording gage (pluviograph), and the monthly and yearly storage gages (totalizers) show some discrepancies in the precipitation catch. There is evidence of seasonal effects in the monthly percentage difference between the catch of the standard and that of other gages. The seasonal pattern is most obvious in the data for the yearly totalizer. In the winter the rain catch for the yearly totalizer is slightly higher than that for the standard gage. Conversely, in the summer the standard gage shows much more rain than the yearly totalizer (Figure 1). Table I erage catch per month in the summer season for all gages. The differences in catch of the rain gages generally used by hydrologists in Europe (standard, pluviograph, and totalizer) should be considered. On the average, over a 10-year period the pluviograph records 3% less precipitation in summer than the standard gage, and the totalizer shows 6.4% less than the standard gage and 10% less than the. ground level gage. There are also variations in total summer catch between the gages from year to year. The maximum difference in summer catch, which ranges between 8 and 14%, was found between the ground level gage and the totalizer ( Table 2). The differences in total summer catch between the standard gage and other gages in various years indicate that there must be one common cause (Figure 2.). In contrast to other gages, only the catch of the ground level gage is higher in summer than that of the 741