In order to assess the degree of resolution lost by estimating rainfall using the RegDer method, the ER was aggregated using two methods (i.e., simple aggregation by resampling and a moving average) and the resulting sequences compared to the IER sequence in the time domain. Plots of progressively more aggregated sequences are shown in Figure 5. It can be seen that as aggregation increases, peaks become lower and more spread out and the sequence is effectively smoothed. The coefficient of determination (*R*_{t}^{2}) and the correlation (*R*) between the aggregated sequence and the IER tends to a maximum then decreases as aggregation time increases – ultimately the variation in the sequence would be completely smoothed out. The point at which the maximum value is reached is taken as an estimate of the resolution of the IER. Plots of *R*_{t}^{2} or *R* values are shown in Figures 6 (aggregation by resampling) and 7 (moving average estimate). Time resolution estimates are shown in Table 1 and compared with the fast time constant (*TC*_{q}) and the N–S sampling limit.

Table 1

. | . | . | . | . | . | Time resolution estimates . | . | |
---|---|---|---|---|---|---|---|---|

Catchment . | Sampling frequency (hr) . | TC (hr)
. _{q} | TC (hr)
. _{s} | SFI . | N–S limit (hr) . | Aggregation by resampling . | Aggregation by moving average . | Cut-off point (hr) . |

Blind Beck | 0.25 | 6.3 | 22.1 | 47% | 19.9 | 2.5 h (10 time periods) | 2.25 h (9 time periods) | 3.8 |

Baru | 0.083 | 1.1 | 18.7 | 62% | 3.4 | 0.9–1 h (11–12 time periods) | 1 h (12 time periods) | 1.7 |

. | . | . | . | . | . | Time resolution estimates . | . | |
---|---|---|---|---|---|---|---|---|

Catchment . | Sampling frequency (hr) . | TC (hr)
. _{q} | TC (hr)
. _{s} | SFI . | N–S limit (hr) . | Aggregation by resampling . | Aggregation by moving average . | Cut-off point (hr) . |

Blind Beck | 0.25 | 6.3 | 22.1 | 47% | 19.9 | 2.5 h (10 time periods) | 2.25 h (9 time periods) | 3.8 |

Baru | 0.083 | 1.1 | 18.7 | 62% | 3.4 | 0.9–1 h (11–12 time periods) | 1 h (12 time periods) | 1.7 |

Figure 5

Figure 6

Figure 7

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