Three-Dimensional Variational Data Assimilation with Rapid Update Cycling for Short-Range Precipitation Forecasting: A Case Study of Heavy Rainfall in Bali, Indonesia

Fuente: arXiv
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Main Authors: Trilaksono, Nurjanna Joko, Herho, Sandy Hardian Susanto, Wistika, I Putu Ferry, Fajary, Faiz Rohman, Suwarman, Rusmawan, Irawan, Dasapta Erwin
Format: Preprint
Published: 2026
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author Trilaksono, Nurjanna Joko
Herho, Sandy Hardian Susanto
Wistika, I Putu Ferry
Fajary, Faiz Rohman
Suwarman, Rusmawan
Irawan, Dasapta Erwin
author_facet Trilaksono, Nurjanna Joko
Herho, Sandy Hardian Susanto
Wistika, I Putu Ferry
Fajary, Faiz Rohman
Suwarman, Rusmawan
Irawan, Dasapta Erwin
contents This study evaluates the effectiveness of three-dimensional variational (3D-Var) data assimilation coupled with a Rapid Update Cycle (RUC) framework for improving short-range precipitation forecasts over the Indonesian Maritime Continent (IMC). We employ the Weather Research and Forecasting (WRF) model and its data assimilation component (WRFDA) to assimilate surface observations from Automatic Weather Stations (AWS) at cycling intervals of 1, 3, 6, and 12 hours. Our test case is a heavy rainfall event on 7 July 2023 in Bali Province, during which accumulated precipitation exceeded 193 mm.day$^{-1}$. The 1-hour cycling interval yields the lowest root-mean-square error (RMSE) for both 2-meter temperature (0.0-0.3$\,^\circ$C) and hourly precipitation (1.295 mm.h$^{-1}$), corresponding to reductions of roughly 75% and 57%, respectively, relative to non-assimilated forecasts. Frequent cycling constrains initial-condition errors and captures mesoscale convective evolution, as confirmed by improved spatial agreement with radar reflectivity observations. These results demonstrate that high-frequency assimilation cycling offers clear advantages for nowcasting in tropical maritime environments.
format Preprint
id arxiv_https___arxiv_org_abs_2603_20468
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Three-Dimensional Variational Data Assimilation with Rapid Update Cycling for Short-Range Precipitation Forecasting: A Case Study of Heavy Rainfall in Bali, Indonesia
Trilaksono, Nurjanna Joko
Herho, Sandy Hardian Susanto
Wistika, I Putu Ferry
Fajary, Faiz Rohman
Suwarman, Rusmawan
Irawan, Dasapta Erwin
Atmospheric and Oceanic Physics
86A10, 86A22, 65K10
This study evaluates the effectiveness of three-dimensional variational (3D-Var) data assimilation coupled with a Rapid Update Cycle (RUC) framework for improving short-range precipitation forecasts over the Indonesian Maritime Continent (IMC). We employ the Weather Research and Forecasting (WRF) model and its data assimilation component (WRFDA) to assimilate surface observations from Automatic Weather Stations (AWS) at cycling intervals of 1, 3, 6, and 12 hours. Our test case is a heavy rainfall event on 7 July 2023 in Bali Province, during which accumulated precipitation exceeded 193 mm.day$^{-1}$. The 1-hour cycling interval yields the lowest root-mean-square error (RMSE) for both 2-meter temperature (0.0-0.3$\,^\circ$C) and hourly precipitation (1.295 mm.h$^{-1}$), corresponding to reductions of roughly 75% and 57%, respectively, relative to non-assimilated forecasts. Frequent cycling constrains initial-condition errors and captures mesoscale convective evolution, as confirmed by improved spatial agreement with radar reflectivity observations. These results demonstrate that high-frequency assimilation cycling offers clear advantages for nowcasting in tropical maritime environments.
title Three-Dimensional Variational Data Assimilation with Rapid Update Cycling for Short-Range Precipitation Forecasting: A Case Study of Heavy Rainfall in Bali, Indonesia
topic Atmospheric and Oceanic Physics
86A10, 86A22, 65K10
url https://arxiv.org/abs/2603.20468