Comparison of different techniques for the measurement of precipitation in tropical montane rain forest regions

Characteristics of different precipitation measurements in a tropical mountain valley in southern Ecuador are compared in this study to determine potential errors. The instruments are used for different ecological purposes like erosion studies, through fall measurements, investigation of atmospheric chemistry, and modeling of area rainfall distribution. Five recording devices (two precipitation radars, an electro-optical present weather sensor, and two tipping buckets) and three totaling gauges were operated in parallel at a designated site. Data were taken between 1998 and 2003 with different temporal resolution and different operational periods. The general agreement between the instruments is rather good; deviations are in the expected range of 10%-20% of the annual total of about 2200 mm. The remote sensing devices are superior in registering the frequent occurrence of light rain but are not capable of detecting the full range of rain intensities observed. The tipping buckets and the totaling gauges are reliable instruments, but a certain fraction of light drizzle and wind-driven rain is not detected. The present weather sensor has the widest range of sensitivity and supplies additional information on drop spectra. All datasets are affected by operational problems (interruptions, synchronization errors); hence, the redundancy given here seems reasonable for an ecosystem study.