Contributed by Dr. Yu-Fen Huang. If you have any questions regarding the paper, please contact Dr. Yu-Fen Huang (yfhuang@hawaii.edu) and Dr. Yinphan Tsang (tsangy@hawaii.edu).
Accurately estimating precipitation in Hawaiʻi presents a unique challenge, primarily due to the region’s distinctive environment characterized by steep rainfall gradients. The sensitivity of small watersheds, responding to rainfall within hours, adds another layer of complexity. Historically, the scarcity of high-temporal and fine-spatial resolution rainfall datasets has hindered our understanding of intricate weather patterns and their hydrological implications.
There are two main types of rainfall observations in Hawaiʻi: radar and rain gauge. Radar provides rain rate over a large spatial area with fine temporal resolution (~every 5 mins) but struggles with accuracy; while rain gauges provide “ground truth” values, but only measure at limited point locations. Building off of a previous effort that compiled hourly gauge and radar data throughout the state of Hawaiʻi (Huang et al. 2022), this study “Deriving Gridded Hourly Rainfall on O‘ahu by Combining Gauge and Radar Rainfall” advances rainfall estimates by merging both types of rainfall data.
By merging radar information with ground-level rain gauge data, a detailed hourly gridded rainfall dataset for Oʻahu was meticulously crafted. Employing the kriging with external drift (KED) method, our research refines rainfall values that were previously estimated by a single instrument. This innovative approach provides valuable insights into the method’s performance across diverse storm types, including tropical cyclones, cold fronts, upper-level troughs, and Kona lows. Furthermore, our findings delve into the accuracy of rainfall estimation concerning various storm types and rainfall structures (stratiform vs. convective) in the Hawaiian context. This research not only addresses existing challenges but also propels our understanding of rainfall dynamics in the unique setting of Hawaiʻi.
Additional information:
The quality-controlled hourly gauge and radar rainfall data are published as “Hourly rainfall data from rain gauge networks and weather radar up to 2020 across the Hawaiian Islands” by Huang et al. (2022) on Scientific Data, Nature, and the data has been shared on Springer Nature, Figshare.
The data includes:
– A summary of available hourly data from various observation networks
– 293-gauge rainfall data from their installation date to the end of 2020
– A 5-year 0.005° by 0.005° gridded radar rainfall dataset between 2016 and 2020 across the
Hawaiian Islands