Evaluation of IMERG Level-3 Products in Depicting the July to October Rainfall over Taiwan: Typhoon Versus Non-Typhoon

Wan-Ru Huang,Cheng-An Lee,Pin-Yi Liu,Ya-Hui Chang

doi:10.3390/rs13040622

Wan-Ru Huang, Cheng-An Lee + Show 2 more

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https://doi.org/10.3390/rs13040622

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Journal: Remote Sensing	Publication Date: Feb 9, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: National Taiwan Normal University

Abstract

This study assesses the performance of satellite precipitation products (SPPs) from the latest version, V06B, Integrated Multi-satellitE Retrievals for Global Precipitation Mission (IMERG) Level-3 (including early, late, and final runs), in depicting the characteristics of typhoon season (July to October) rainfall over Taiwan within the period of 2000–2018. The early and late runs are near-real-time SPPs, while final run is post-real-time SPP adjusted by monthly rain gauge data. The latency of early, late, and final runs is approximately 4 h, 14 h, and 3.5 months, respectively, after the observation. Analyses focus on the seasonal mean, daily variation, and interannual variation of typhoon-related (TC) and non-typhoon-related (non-TC) rainfall. Using local rain-gauge observations as a reference for evaluation, our results show that all IMERG products capture the spatio-temporal variations of TC rainfall better than those of non-TC rainfall. Among SPPs, the final run performs better than the late run, which is slightly better than the early run for most of the features assessed for both TC and non-TC rainfall. Despite these differences, all IMERG products outperform the frequently used Tropical Rainfall Measuring Mission 3B42 v7 (TRMM7) for the illustration of the spatio-temporal characteristics of TC rainfall in Taiwan. In contrast, for the non-TC rainfall, the final run performs notably better relative to TRMM7, while the early and late runs showed only slight improvement. These findings highlight the advantages and disadvantages of using IMERG products for studying or monitoring typhoon season rainfall in Taiwan.

Highlights

Located in East Asia, Taiwan (120◦ E–122◦ E, 22◦ N–25.2◦ N; about 144 km wide, 394 km long) is an island with complex terrains (Figure 1a), making it a valuable location for studying the effects of topography on the movement and structure of typhoons and their related rainfall variations [1,2]
By separating the total rainfall (Figure 2a) into non-TC (Figure 2b) and TC (Figure 2c) rainfall, we note from Central Weather Bureau (CWB) that both consist of two maximum centers, similar to those for total rainfall
The evaluations used more than 400 rain gauges over Taiwan as a reference base for comparisons, and examinations included multiple timescale features, including seasonal mean, daily variation, and interannual variation

Summary

Introduction

Located in East Asia, Taiwan (120◦ E–122◦ E, 22◦ N–25.2◦ N; about 144 km wide, 394 km long) is an island with complex terrains (Figure 1a), making it a valuable location for studying the effects of topography on the movement and structure of typhoons and their related rainfall variations [1,2]. Local researchers might generally use high-density rain-gauge observations [11,12] or the weather radar network data [13,14,15,16,17,18] for the study of TC rainfall; the raw data of these observations usually are not free accessible for “non-local” researchers. Free accessible satellite precipitation products (SPPs) become an important source of information for “non-local” researchers interested in studying TC rainfall over Taiwan

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