Evaluation of precipitation datasets against local observations in southwestern Iran

This study provides a comprehensive evaluation of a great variety of state‐of‐the‐art precipitation datasets against gauge observations over the Karun basin in southwestern Iran. In particular, we consider (a) gauge‐interpolated datasets (GPCCv8, CRU TS4.01, PREC/L, and CPC‐Unified), (b) multi‐sourc...

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Bibliographic Details
Published in:International journal of climatology 2020-07, Vol.40 (9), p.4102-4116
Main Authors: Fallah, Ali, Rakhshandehroo, Gholam Reza, Berg, Peter, O, Sungmin, Orth, Rene
Format: Article
Language:English
Subjects:
Basins
Datasets
Evaluation
Gauges
Hydrologic data
interpolated dataset
Karun basin
Low altitude
Monthly precipitation
Mountainous areas
Precipitation
precipitation datasets
reanalysis dataset
satellite rainfall estimate
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Summary:This study provides a comprehensive evaluation of a great variety of state‐of‐the‐art precipitation datasets against gauge observations over the Karun basin in southwestern Iran. In particular, we consider (a) gauge‐interpolated datasets (GPCCv8, CRU TS4.01, PREC/L, and CPC‐Unified), (b) multi‐source products (PERSIANN‐CDR, CHIRPS2.0, MSWEP V2, HydroGFD2.0, and SM2RAIN‐CCI), and (c) reanalyses (ERA‐Interim, ERA5, CFSR, and JRA‐55). The spatiotemporal performance of each product is evaluated against monthly precipitation observations from 155 gauges distributed across the basin during the period 2000–2015. This way, we find that overall the GPCCv8 dataset agrees best with the measurements. Most datasets show significant underestimations, which are largest for the interpolated datasets. These underestimations are usually smallest at low altitudes and increase towards more mountainous areas, although there is large spread across the products. Interestingly, no overall performance difference can be found between precipitation datasets for which gauge observations from Karun basin were used, versus products that were derived without these measurements, except in the case of GPCCv8. In general, our findings highlight remarkable differences between state‐of‐the‐art precipitation products over regions with comparatively sparse gauge density, such as Iran. Revealing the best‐performing datasets and their remaining weaknesses, we provide guidance for monitoring and modelling applications which rely on high‐quality precipitation input. Topographical map of the Karun basin in Iran. The location of precipitation gauge stations utilized in this study is marked with purple diamonds and triangles (synoptic stations).
ISSN:0899-8418
1097-0088
DOI:10.1002/joc.6445