2.3.1. Quality Control

All four SBP products are gridded datasets, and the gauge observed datasets are at the point scale, i.e., fixed at a single location on the ground surface. Therefore, a point-to-pixel comparison was performed to compare the point-based gauge observed data with the gridded precipitation datasets [65–68]. We extracted SBP estimates for the station locations instead of interpolating the gauge observations to avoid accumulating additional errors by gridding the observed data [69–71]. These SBP rates were first aggregated to obtain daily timescale records using DHM daily precipitation measurement time windows (03 UTC). Some of the station data feature missing values, and quality control was conducted for data consistency; if the gauge-observed daily data contained missing values, then the corresponding daily SBP data were simultaneously considered to be a missing value. The monthly data were computed when the station had more than 25 days of precipitation data available in a month; otherwise, the precipitation in that month was considered as a missing value. Similarly, the monthly SBP data were also considered a missing value for consistency if the corresponding monthly data were missing from the gauge observed datasets.

Mean, and summer (JJAS) mean monsoonal precipitation of SBP and gauge observed datasets during the study period were calculated for each station. Mean monthly regional datasets were computed for three regions, with stations located at longitudes of 80–82◦E, 83–85◦E and 86–88◦E being grouped together as the western, central, and eastern regions, respectively (Figure 1). The stations were divided into three different physiographic regions (elevation intervals) to quantify the spatial patterns of SBP products. All stations below 1500 m, between 1500 and 2500, and above 2500 m, were aggregated into the low-elevation, mid-elevation, and high-elevation regions, respectively.

We also classified the gauge observed summer monsoon precipitation based on precipitation rate; all stations with mean monsoonal precipitation rates of less than 10 mm/day, between 10 and 20 mm/day, and higher than 20 mm/day was assigned to be lower, moderate, and higher precipitation zones, respectively. This allows analysis of SBP performances for different precipitation rates. The high-intensity related extreme rainfall events in four SBP datasets exceeding the 95th percentile (R95p) of observed precipitation was also examined. To do this, only those stations were selected when daily observed data was available more than 90% per year. The overall processes followed in the study is shown in Figure 2.
