Mean and extreme precipitation over Aotearoa New Zealand: A comparison across multiple different estimation techniques

Abstract

This study provides a comprehensive evaluation of mean and extreme precipitation features over Aotearoa New Zealand (hereafter New Zealand or NZ) in station data and in six merged satellite‐gauge products, five reanalyses and two in situ gridded products over a period of 10 years inclusive (2001–2010). All products show a similar mean precipitation pattern with a clear maximum over alpine regions. However, only the higher spatial resolution datasets capture the details of the west–east gradient across the South Island accurately. For extremes, we used a set of climate indices to examine the wet tail of the precipitation distribution in the different products. The products have significant differences in these indices, especially over the West Coast in the South Island, indicating substantial uncertainty in these gridded precipitation extremes. Overall, MSWEP and BARRA‐R perform well in all the statistical tests, including higher values of the nonparametric Kling Gupta efficiency (NP‐KGE) metric, favouring their utility for capturing the main characteristics of both mean and extreme precipitation across New Zealand.