Satellite products, such as the Integrated Multi-Satellite Retrievals of IMERG from the Global Precipitation Measurement (GPM) mission, have emerged as promising tools to analyze precipitation distribution and extremes, particularly in regions with low rain gauge density and sparse distribution, such as Brazil. However, regional validation of satellite data is crucial. In this context, the validation of GPM (IMERG) for the Parnaíba River Basin in northeastern Brazil is important due to its high hydrological potential and the presence of one of the largest expanding agricultural frontiers in the world. This study evaluates the estimation capacity of IMERG version 6 satellite data, including IMERG Early, Late, and Final products, for extreme precipitation in the Parnaíba River Basin from 2001 to 2020. A pixel point-to-point approach is used to compare the satellite estimates with observed precipitation data measured by rain gauges. Eight indices of extreme precipitation are analyzed, along with statistical measures such as bias, mean square error, root mean square error, probability of detection (POD), false alarm ratio (FAR), and the Kling-Gupta efficiency (KGE) index and its components. The results show that the IMERG Final estimates exhibit better agreement with in situ data at the daily scale compared to the IMERG Early and Late estimates. The lower Parnaíba region shows higher POD values, while the middle Parnaíba region exhibits higher KGE values, particularly in tropical climate areas. The IMERG products demonstrate different capabilities in observing extreme rainfall in the basin, with IMERG Final showing satisfactory results for 50 % of the analyzed indices, performing more robustly in capturing the PRCPTOT index and reasonably for CDD, RX5day, and R95p. We conclude that the IMERG Final product can be used as a data source for analyzing precipitation extremes in the Parnaíba River Basin, with bias adjustment recommended for better performance at the daily scale.

卫星产品，例如全球降水测量 (GPM) 任务中的 IMERG 综合多卫星反演，已成为分析降水分布和极端情况的有前途的工具，特别是在雨量计密度低且分布稀疏的地区，例如巴西。然而，卫星数据的区域验证至关重要。在此背景下，巴西东北部帕纳伊巴河流域的 GPM (IMERG) 验证非常重要，因为该流域水文潜力巨大，而且是世界上最大的农业前沿之一。本研究评估了IMERG第6版卫星数据（包括IMERG早期、晚期和最终产品）对2001年至2020年帕纳伊巴河流域极端降水的估计能力。采用像素点对点的方法来比较卫星数据利用雨量计测量的观测降水数据进行估计。分析了极端降水的八个指数，以及偏差、均方误差、均方根误差、检测概率 (POD)、误报率 (FAR) 和克林-古普塔效率 (KGE) 指数等统计指标。它的组成部分。结果表明，与 IMERG 早期和晚期估计相比，IMERG 最终估计与每日尺度的现场数据表现出更好的一致性。较低的帕尔纳伊巴地区显示出较高的 POD 值，而中部的帕尔纳伊巴地区则表现出较高的 KGE 值，特别是在热带气候地区。 IMERG 产品在观测流域极端降雨方面表现出不同的能力，其中 IMERG Final 对 50% 的分析指数显示出令人满意的结果，在捕获 PRCPTOT 指数方面表现更加稳健，对于 CDD、RX5day 和 R95p 表现也相当合理。我们的结论是，IMERG 最终产品可用作分析帕纳伊巴河流域极端降水的数据源，并建议进行偏差调整，以在日尺度上获得更好的性能。