# Evaluating the Latest IMERG Products in a Subtropical Climate: The Case of Parana State, Brazil
## 5 Conclusions  
In this study, the performance of IMERG version 6 products in estimating daily and monthly precipitation were evaluated in comparison with the data observed by 511 gauges distributed in the state of Parana in Brazil. The results showed better metrics for monthly precipitation. In summary, the main findings of this study were as follows:  
1. The volume and spatial distribution of observed and estimated rainfall are consistent across all months of the year in the monthly products of IMERG version 6, with similar rainfall distribution density curves.
2. IMERG version 6 has a good relationship between precipitation estimates and those observed by gauges on the monthly time scale, with high correlation and accuracy, and low errors in statistical metrics. However, a lower performance was observed in estimating rainfall in regions with abrupt changes in topography along the coast, related to the lower accuracy when estimating orographic affected rainfall.
3. The monthly products of IMERG version 6 performed very close to perfect considering qualitative assessments for the detection of rainfall events in this time scale throughout the study area.  
* The daily estimates of IMERG version 6 were limited in representing the rainfall observed by the gauges, with little correlation between the data and low values of rain event detection rates. Although the gauges are direct observations and considered references, it is known there is great spatial variability in daily data, which is the probable cause of the low performance.
* The detection of anomalies by the monthly products of IMERG version 6 showed limited performance over the years analyzed and the study area, probably due to the topography and rainfall regime in the northeast, coast, and southeast.  
Based on the results presented here, IMERG version 6 can be used as a source of monthly precipitation data over the territory of Parana. However, on a daily scale, prior calibration of the product is recommended to ensure the positive performance of the estimate on this time scale, especially for mountainous areas. Future improvements to IMERG version 6 products may increase its accuracy and favor its application for the detection of rain in coastal areas and anomalies. Also, studies that consider seasonal analyses and other time scales (hourly and half-hourly), areas with complex topographies, and the other products of IMERG version 6 (Early and Late Run) are recommended.  
Conceptualization, all the authors; methodology, J.G.N., D.A. and H.C.B.; software and validation D.A.; writing--original draft preparation, J.G.N. D.A. and H.C.B.; writing--review and editing, all the authors. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES-In English: Coordination of Improvement of Higher Education Personnel)--Finance code 001. Additional funding from the Daugherty Water for Food Global Institute at the University of Nebraska is also appreciated.  
The authors declare no conflict of interest.