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1. Indian Monsoon Rainfall

   https://doi.org/10.14379/iodp.proc.353.2016  

   Clemens, S.C.; Kuhnt, W.; LeVay, L.J. (July 2016, Proceedings of the International Ocean Discovery Program)

   null (Ed.)

   International Ocean Discovery Program (IODP) Expedition 353 drilled six sites in the Bay of Bengal, recovering 4280 m of sediments during 32.9 days of on-site drilling. The primary objective of Expedition 353 is to reconstruct changes in Indian monsoon circulation since the Miocene at tectonic to centennial timescales. Analysis of the sediment sections recovered will improve our understanding of how monsoonal climates respond to changes in forcing external to the Earth’s climate system (i.e., insolation) and changes in forcing internal to the Earth’s climate system, including changes in continental ice volume, greenhouse gas concentrations, sea level, and the ocean-atmosphere exchange of energy and moisture. All of these mechanisms play critical roles in current and future climate change in monsoonal regions. The primary signal targeted is the exceptionally low salinity surface waters that result, in roughly equal measure, from both direct summer monsoon precipitation above the Bay of Bengal and runoff from the numerous large river basins that drain into the Bay of Bengal. Changes in rainfall and surface ocean salinity are captured and preserved in a number of chemical, physical, isotopic, and biological components of sediments deposited in the Bay of Bengal. Expedition 353 sites are strategically located in key regions where these signals are the strongest and best preserved. 

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2. Deriving Gridded Hourly Rainfall on O‘ahu by Combining Gauge and Radar Rainfall

   https://doi.org/10.1175/JHM-D-22-0196.1  

   Huang, Yu-Fen; Tsang, Yinphan; Nugent, Alison_D (December 2023, Journal of Hydrometeorology)

   Abstract High temporal and spatial resolution precipitation datasets are essential for hydrological and flood modeling to assist water resource management and emergency responses, particularly for small watersheds, such as those in Hawai‘i in the United States. Unfortunately, fine temporal (subdaily) and spatial (<1 km) resolutions of rainfall datasets are not always readily available for applications. Radar provides indirect measurements of the rain rate over a large spatial extent with a reasonable temporal resolution, while rain gauges provide “ground truth.” There are potential advantages to combining the two, which have not been fully explored in tropical islands. In this study, we applied kriging with external drift (KED) to integrate hourly gauge and radar rainfall into a 250 m × 250 m gridded dataset for the tropical island of O‘ahu. The results were validated with leave-one-out cross validation for 18 severe storm events, including five different storm types (e.g., tropical cyclone, cold front, upper-level trough, kona low, and a mix of upper-level trough and kona low), and different rainfall structures (e.g., stratiform and convective). KED-merged rainfall estimates outperformed both the radar-only and gauge-only datasets by 1) reducing the error from radar rainfall and 2) improving the underestimation issues from gauge rainfall, especially during convective rainfall. We confirmed the KED method can be used to merge radar with gauge data to generate reliable rainfall estimates, particularly for storm events, on mountainous tropical islands. In addition, KED rainfall estimates were consistently more accurate in depicting spatial distribution and maximum rainfall value within various storm types and rainfall structures. Significance StatementThe results of this study show the effectiveness of utilizing kriging with external drift (KED) in merging gauge and radar rainfall data to produce highly accurate, reliable rainfall estimates in mountainous tropical regions, such as O‘ahu. The validated KED dataset, with its high temporal and spatial resolutions, offers a valuable resource for various types of rainfall-related research, particularly for extreme weather response and rainfall intensity analyses in Hawai’i. Our findings improve the accuracy of rainfall estimates and contribute to a deeper understanding of the performance of various rainfall estimation methods under different storm types and rainfall structures in a mountainous tropical setting. 

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3. Rainfall Thresholds for Postfire Debris‐Flow Initiation Vary With Short‐Duration Rainfall Climatology

   https://doi.org/10.1029/2024JF007781  

   Cavagnaro, David B; McCoy, Scott W; Lindsay, Donald N; McGuire, Luke A; Kean, Jason W; Trugman, Daniel T (June 2025, Journal of Geophysical Research: Earth Surface)

   The size, frequency, and geographic scope of severe wildfires are expanding across the globe, including in the Western United States. Recently burned steeplands have an increased likelihood of debris flows, which pose hazards to downstream communities. The conditions for postfire debris‐flow initiation are commonly expressed as rainfall intensity‐duration thresholds, which can be estimated given sufficient observational history. However, the spread of wildfire across diverse climates poses a challenge for accurate threshold prediction in areas with limited observations. Studies of mass‐movement processes in unburned areas indicate that thresholds vary with local climate, such that higher rainfall rates are required for initiation in climates characterized by frequent intense rainfall. Here, we use three independent methods to test whether initiation of postfire runoff‐generated debris flows across the Western United States varies similarly with climate. Through the compilation of observed thresholds at various fires, analysis of the spatial density of observed debris flows, and quantification of feature importance at different spatial scales, we show that postfire debris‐flow initiation thresholds vary systematically with short‐duration rainfall‐intensity climatology. The predictive power of climatological data sets that are readily available before a fire occurs offers a much‐needed tool for hazard management in regions that are facing increased wildfire activity, have sparse observational history, and/or have limited resources for field‐based hazard assessment. Furthermore, if the observed variation in thresholds reflects long‐term adjustment of the landscape to local climate, rapid shifts in rainfall intensity related to climate change will likely induce spatially variable shifts in postfire debris‐flow likelihood. 

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4. Rainfall, River Height, and Local Relevance

   Brase, Lauren E; Mossa, Lindsay C; Robeck, Edward C (June 2023, Science and children)

   The inclusion of a specific natural disaster, hands-on models, and other multimedia experiences engaged students to learn about rivers and flooding. It was clear through verbal and written comments that students understood concepts related to flooding (water movement, land cover, etc.) and were able to reason with data--both their data from the stream tables and professionally collected data about river height and rainfall. These lessons provide many possibilities focused on community-relevant anchoring phenomena related to natural hazards, how human activity affects the incidence of these hazards, and how people can work toward reducing the occurrence, severity, and impact of natural hazards. 

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5. Rainfall, River Height, and Local Relevance

   Brase, L .E.; Mossa, L. C.; Robeck, E. C. (May 2023, Science and children)