Evaluation and restructuring of gridded precipitation data over the Greater Mekong Subregion

Abstract

Precipitation measurements in the Mekong River Basin (MRB) are full of variability due to this domain's varied weather systems, climate conditions, elevation, and specific land–atmosphere interactions. This study provides an in‐depth evaluation of the differences between four gridded precipitation products [i.e. Asian Precipitation—Highly‐Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE), Tropical Rainfall Measuring Mission (TRMM), CPC MORPHing technique (CMORPH), and Climatic Research Unit (CRU)] over the Greater Mekong Subregion. Precipitation data from a total of 242 stations in this domain are used to investigate the quality of the gridded products. Our analysis verifies that gauge‐based APHRODITE exhibits the highest correlations with the station data as well as the highest probability of detection of daily precipitation. The false alarm ratio, on the other hand, is slightly in favour of TRMM and CMORPH. Subtracting APHRODITE (as baseline) from TRMM and CMORPH reveals the spatial and frequency distribution of potential biases. The results indicate that TRMM appears to have a wet bias in most areas, while CMORPH shows no similar or consistent bias over APHRODITE. To utilize the higher accuracy of APHRODITE and the finer spatial and temporal footprints of CMORPH, a new restructuring algorithm is introduced in this study. The algorithm is capable of eliminating biases and possible artefacts associated with CMORPH while resolving the resolution discrepancies between the two data sets.

Assessing the Uncertainties of Four Precipitation Products for Swat Modeling in Mekong River Basin

“…While the TMPA precipitation estimates outperforms the other three precipitation products with the lowest ME, which are mainly due to its poor sampling [15]. This finding is consistent with the results of Chen et al [21]. Based on the three categorical statistical indices (POD, FAR, CSI), this study shows that all the four precipitation products have the capacity of detecting the precipitation events with relative high POD and CSI.…”

“…Based on the three categorical statistical indices (POD, FAR, CSI), this study shows that all the four precipitation products have the capacity of detecting the precipitation events with relative high POD and CSI. Among the preexisting studies, these studies show that the APHRODITE has a good performance compared with TMPA, CMORPH, CRU, and ERA-Interim and CFSR [21,30,31,39]. To our best knowledge, MSWEP has been applied for the first time to the MRB, and we found that this product outperforms the APHRODITE during the period of 1951-2007.…”

“…Rain gauge is a traditional means of obtaining ground precipitation information, however, the traditional rainfall station network is sparse, and its point observation is also difficult to reflect the spatial distribution of precipitation [15,[18][19][20]. For transnational rivers, collecting gauge observations is also very difficult from the management departments of different countries (e.g., Mekong River Basin which flows through six countries) [21]. The sparse and poor spatial representation of rain gauges can lead to inaccurate precipitation inputs to hydrological models, especially for a larger study area with complex topography and climate like Mekong River Basin [22].…”

“…Numerous studies have been conducted to evaluate satellite-based and reanalysis precipitation products in the Mekong River Basin (MRB) by using statistical and hydrological simulation approaches. Several studies directly compared the satellite-based and reanalysis precipitation estimates (i.e., APHRODITE, CMORPH, TRMM, and CRU) with gauge observations, and they found that the APHRODITE product, which provides daily precipitation from 1951 to 2007, has the highest correlations and highest probability of detections with the daily gauge observations [21,30]. In terms of evaluating the capacity of precipitation products to reconstruct the streamflow process using hydrological model, Lauri et al [31] and Chen et al [30] found that APHRODITE can reproduce the daily streamflow process of main stream of the MRB, while CMORPH and TRMM may need further corrections.…”

Development of Asia Pacific Weather Statistics (APWS) dataset for use in Soil and Water Assessment Tool (SWAT) simulation

“…APHRODITE has been used in the Asia Pacific region as baseline rainfall series for drought analysis (Um et al, 2017;Sohn et al, 2012), climate model 80 assessments (Khan et al, 2018;Cruz and Sasaki, 2017), climate change impact assessments (Apurv et al, 2015;Kulkarni et al, 2013) and hydrological model setup (Lauri et al, 2014;Panday et al, 2014). Moreover, APHRODITE's relative superiority over other rainfall products, including CFSR, is well-established in several countries in the Asia Pacific region, including Saudi Arabia (El Kenawy and McCabe, 2016), Greater Mekong (Chen et al, 2017), Bhutan (Awange and Forootan, 2016), China (Yang et al, 2014;Tang et al, 2019) and many others. The better performance of APHRODITE over CFSR and other products 85 in the region suggests that rainfall statistics derived from APHRODITE data could be more precise, and hence, more effective in generating relatively accurate synthetic weather data and better flow simulations using SWAT in rainfall dominant basins of Asia.…”