What is “relative error” in the TRMM 3B42 and 3B43 data sets?
The “relative error” is the random error discussed below. The accuracy of the precipitation products can be broken into systematic departures from the true answer (bias) and random fluctuations about the true answer (sampling), as discussed in Huffman (1997). The former are the biggest problem for climatological averages, since they will not average out. For short averaging periods, however, the low number of samples and/or algorithmic inaccuracies tend to present a more serious problem for individual microwave data sets. That is, the sampling is spotty enough that the collection of values over, say, one day may not be representative of the true distribution of precipitation over the day. For VAR, the sampling is good, but the algorithm likely has substantial RMS error due to the weak physical connection between IR Tb’s and precipitation. Accordingly, the “random error” is assumed to be dominant, and estimates could be computed as discussed in Huffman (1997). Random error cannot be cor
