In this study, we evaluated the three satellite precipitation products (TRMM-3B42V7, GPM-IMERGV6, PERSIANN-CDR) compared to IMD gridded precipitation products using statistical metrics such as CC RMSE, MAE, RB, and SD, as shown in Table 4. As per statistical metrics of all precipitation products at a daily time scale, GPM-IMERGV6 has a better correlation value (0.48) compared to TRMM-3B42V7 (0.44) and PERSIANN-CDR (0.36) precipitation products. The GPM-IMERGV6 product has the lowest error value in terms of RMSE (9.5 mm/d) and MAE (3.8 mm/d) compared to TRMM-3B42V7 and PERSIANN-CDR data. Thus, based on statistical metrics, GPM-IMERGV6 is close to the IMD precipitation product. PERSIANN-CDR data show inferior performance compared to the TRMM-3B42V7 and GPM-IMERGV6. The three satellite products (TRMM-3B42V7, IMERGV6, PERSIANN-CDR) seem to overestimate precipitation amount compared to IMD precipitation amount for the period of 2000–2018 as the negative percentage bias (%) range from 3.8% (GPM-IMERGV6) to 22.4% (PERSIANN-CDR). The standard deviation was low (9 mm) for TRMM-3B42V7 and was 9.5 and 12 mm for GPM-IMERGV6 and PERSIANN satellite precipitation products. Overall, the IMERGV6 and PERSIANN-CDR products showed the best and worst performance, respectively, based on five statistical metrics, as shown in Table 4.
Comparison of continuous statistical metrics of all precipitation products at daily, monthly, and yearly time scale at watershed scale
Statistical Indicator . | Daily . | Monthly . | Yearly . | ||||||
---|---|---|---|---|---|---|---|---|---|
TRMM . | GPM . | PERSIANN . | TRMM . | GPM . | PERSIANN . | TRMM . | GPM . | PERSIANN . | |
Correlation | 0.44 | 0.48 | 0.36 | 0.94 | 0.93 | 0.78 | 0.62 | 0.62 | 0.23 |
RMSE | 9.58 | 9.52 | 12.35 | 41.60 | 43.16 | 63.61 | 212.67 | 182.46 | 256.24 |
MAE | 3.97 | 3.84 | 5.39 | 26.75 | 27.86 | 36.93 | 169.99 | 160.00 | 278.89 |
SD | 9.0 | 9.5 | 12.0 | 121.6 | 117.4 | 167.9 | 187.0 | 168.6 | 204.1 |
Percent Bias (%) | −8.7 | −3.8 | −52.4 | −8.7 | −3.8 | −52.4 | −8.7 | −3.8 | −52.4 |
Statistical Indicator . | Daily . | Monthly . | Yearly . | ||||||
---|---|---|---|---|---|---|---|---|---|
TRMM . | GPM . | PERSIANN . | TRMM . | GPM . | PERSIANN . | TRMM . | GPM . | PERSIANN . | |
Correlation | 0.44 | 0.48 | 0.36 | 0.94 | 0.93 | 0.78 | 0.62 | 0.62 | 0.23 |
RMSE | 9.58 | 9.52 | 12.35 | 41.60 | 43.16 | 63.61 | 212.67 | 182.46 | 256.24 |
MAE | 3.97 | 3.84 | 5.39 | 26.75 | 27.86 | 36.93 | 169.99 | 160.00 | 278.89 |
SD | 9.0 | 9.5 | 12.0 | 121.6 | 117.4 | 167.9 | 187.0 | 168.6 | 204.1 |
Percent Bias (%) | −8.7 | −3.8 | −52.4 | −8.7 | −3.8 | −52.4 | −8.7 | −3.8 | −52.4 |