## 4 Results  
### Evaluation of Temporal and Spatial Dynamics  
Annual and Seasonal Scale  
The annual averages of precipitation, as estimated from reference and gridded data products (GPPs) over Punjab region, are shown in Figure 2. The temporal trends indicated that the annual precipitation amounts that were underestimated by the GPPs with the exception of TRMM and PERSIANN-CDR products, which overestimated the magnitude as compared with the reference data. The temporal magnitude in all the precipitation products was different and deviate up to 100-200 mm as compared with in-situ measurements. However, the most identical temporal fluctuation pattern of precipitation was observed in GPCC and TRMM products with the relative mean error of \(-16.59\%\) and \(2.88\%\), respectively. Figure 3 illustrates the spatial distribution of GPPs and observed annual average precipitation. The results indicated that, the spatial configuration of GPPs exhibited the similar pattern of precipitation as compared with observed estimates. Across all of the GPPs, the northern part of study area received more amount of precipitation than southern part and exhibited the precipitation pattern towards south to north gradient with the range of 15-1500 mm. In all GPPs, the spatial consistency was observed with a major deviation in northern Punjab. However, the most accurate and consistent spatial pattern was observed in GPCC and TRMM product and the lowest spatial accuracy was observed in CPC following by UDel and PERSIANN-CCS products particularly in northern Punjab. These products were relatively less accurate to capture the higher amount of precipitation distribution over the northern part of the study region. In contrast, the APHRODITE product showed less precipitation magnitude in the central and southern Punjab as compared with observed precipitation. The spatial distribution of the APHRODITE product showed better results at high catchments of the study region as compared with plain areas. These results are consistent with the findings of [27], who reported the better performance of APHRODITE product as compared with reference data at high-altitude catchments in Pakistan. The descriptive statistical measures divulge the characteristics of GPPs when compared with the reference data. Figures 4-6 indicates the plots as A (GB) and B (SB) precipitation products against the reference data during annual, winter, and summer monsoon, respectively. The result showed that, all the selected GPPs underestimated the annual precipitation amount, except TRMM and PERSIANN-CDR  
Figure 3: Spatial distribution of annual average of (**A**) GB and (**B**) SB precipitation products during the whole study periods. Figure 2: Mean annual variation in GPPs and reference data. product, which indicates the overestimation of precipitation over the study region. The highest accuracy was observed in the GPCC and TRMM products with lowest mean error and higher R-squared value with the magnitude of \(-\)76.35 (0.90) and 14.26 mm (0.90) respectively. These products are comparatively better to capture the annual precipitation variability over the study region. However, the lowest accuracy was observed in CPC and PERSIANN-CCS products with the magnitude of mean error \(-\)163.57 (\(-\)34.71%) and \(-\)16.08 mm (\(-\)3.23%), respectively. These datasets are relatively less accurate for capturing the annual variability amount of precipitation during the whole study period. Moreover, the GSMap and PERSIANN-CCS products overestimated the precipitation magnitude \(\leq\) 500 mm and underestimated the precipitation amounts, which are \(\geq\) 500 mm. The inter-comparison of gridded products indicated a similar consistency, except TRMM and PERSIANN-CDR products, which showed positive bias. The underestimation was more conspicuous in GB products as compared with SB products. The SB products showed lower bias and higher accuracy as compared with GB products, which could be due to higher pixel resolution of SB products over the study region [28].