## 4 Results  
### Statistical Assessment of Multiple SPPs  
#### 4.1.1 Precipitation at Gauge-Located Grid Cells  
Figure 4a,b demonstrates that 3B42 RT overestimates precipitation in daytime and nighttime at all seven rain gauges, with mean BIAS values of 16.9% and 29.9%, respectively. 3B42V7 effectively reduces the systematic errors of 3B42 RT at most rain gauges with bias-correction using the GPCC monthly gauge-analysis precipitation data set and with mean BIAS values of \(-2\%\) and 4.5% for daytime and nighttime, respectively. The two near-real-time IMERG SPPs (IMERG-E and IMERG-L) largely underestimate daytime and nighttime precipitation at six out of the seven gauges. Bias-adjustment with the GPCC precipitation data set shows that the post-real-time product IMERG-F averagely reduces the systematic errors to \(-4.2\%\) and \(-5.1\%\) for daytime and nighttime precipitation, respectively. All three GSMaP SPPs tend to underestimate precipitation at most rain gauges. Although the post-real-time product GSMaP-GAUGE was calibrated with the CPC precipitation data, it significantly underestimates daytime and nighttime precipitation by 44.3% and 43.8% on average, with higher magnitudes of underestimation than those by GSMaP-NRT and GSMaP-MVK. Figure 4c,d show that the CC values of the 3-hourly daytime precipitation estimates from all eight SPPs are generally lower than those of the 12-hourly nighttime precipitation retrievals. The three IMERG SPPs obtain slightly higher CC values than their predecessor--that is, TMPA products--at most rain gauges. The averaged CCs for the 3-hourly daytime precipitation estimates from IMERG-E, IMERG-L, and IMERG-F are 0.387, 0.412, and 0.400, respectively, while those for 3B42 RT and 3B42V7 are 0.376 and 0.361, respectively. In the case of the 12-hourly nighttime precipitation retrievals, the mean CCs increase to 0.556, 0.588, and 0.593 for IMERG-E, IMERG-L, and IMERG-F, respectively, and those for 3B42 RT and 3B42V7 are 0.547 and 0.554, respectively. GSMaP-MVK has the highest averaged CC (0.416) for daytime precipitation estimation, but the CC values of GSMaP-NRT and GSMaP-GAUGE are relatively low (0.341 and 0.367, respectively). On average, all three GSMaP-based 12-hourly nighttime precipitation time series are in poorer correlations with the ground observations  
than TMPA and IMERG, which have mean CC values of 0.472, 0.510, and 0.486 for GSMaP-NRT, GSMaP-MVK, and GSMaP-GAUGE, respectively. Figure 4: Statistical indices of the precipitation estimates from eight SPPs at seven weather stations in the Chindwin River basin in the period of 1 April 2014–31 December 2016. Concerning the absolute errors of satellite precipitation estimates, GSMaP-NRT has the highest RMSEs among all the near-real-time products for both time slots, with mean RMSE values of 3.9 mm in the daytime and 9.7 mm in the nighttime, whereas IMERG-L provides the lowest averaged RMSEs (3.3 and 8.0 mm in the daytime and nighttime, respectively) (Figure 4e,f). For the four post-real-time SPPs, IMERG-F obtains a slightly higher averaged RMSE (3.6 mm) than do 3B42V7 (3.5 mm), GSMaP-MVK (3.3 mm), and GSMaP-GAUGE (3.4 mm) for the 3-hourly daytime precipitation estimations. However, the averaged RMSE values in the nighttime precipitation retrievals from GSMaP-MVK and GSMaP-GAUGE (9.3 and 9.1 mm, respectively) are higher than those from 3B42V7 (8.5 mm) and IMERG-F (8.2 mm). With respect to the contingency of SPPs, the POD values are lower at all the weather stations on the 3-h temporal scale in daytime than those on the 12-h scale in nighttime (Figure 4g,h). Among all the near-real-time products, IMERG-L obtains the highest PODs (averaged PODs = 0.217 and 0.433) for daytime and nighttime precipitation estimates, and the lowest PODs exist in the GSMaP-NRT daytime precipitation estimates (0.173) and the 3B42 RT nighttime precipitation retrievals (0.320).